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361 results in Bioengineering

Page 10 of 19

  • The efficacy of feeding a live probiotic yeast, Yea-Sacc®, on the performance of lactating dairy cows

  • D. Tristant, C. A. Moran
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    22 October 2015, e12
    Print publication:
    2015

  • The following trial was conducted to evaluate the impact of feeding Yea-Sacc® (YS; Alltech Inc, USA), a zootechnical feed additive based on a live probiotic strain of Saccharomyces cerevisiae, to lactating dairy cows over a 12 week period. Sixty-four primiparous and multiparous Holstein dairy cows, grouped to give similar range of parity, physiological and milk production stages, were selected for the study. Cows were equally allocated to either a control feed group or a diet supplemented with YS (32 cows per treatment). The test diet was formulated to include YS (Yea-Sacc® Farm Pak) incorporated in the total mixed ration (TMR), supplying a target dose of 5 × 107 CFU/kg feed dry matter (DM). This target dose delivered 1 × 109 CFU/cow/day, for a cow consuming 20 kg feed (DM basis) daily. Each cow was considered a replicate unit. Cows were fed a nutritionally adequate total TMR plus hay and a supplementary protein/energy concentrate (calculated according to milk yield) for 12 weeks, supplied once a day after the morning milking. Weigh backs of feed were recorded daily, with refusals being maintained at 3% of the total intake. During the 12 week study period, YS had significant beneficial effects on milk production (+0.8 kg/day; P = 0.003), energy corrected milk production (+1.4 kg/day; P < 0.0001), synthesis of milk protein (+36 g/day; P = 0.001), milk protein content (+0.3 g/kg; P = 0.009), and milk urea content (−0.09 mg/l; P = 0.004). The synthesis of milk fat was similar between treatments but milk fat content was lower for the YS group compared to the control group (−1.1 g/kg; P = 0.0002). Lactose content was always higher (+0.8 g/kg; P < 0.0001) for the YS group, indicating enhanced energy utilisation. In general, the effect of YS was higher during the first study period (one to seven weeks), when cows were in early lactation and the production potential was higher. YS cows produced significantly more milk during the study, and an additional 220 kg milk per cow was sold from this group from the output measured from the beginning of the study to two weeks post-trial. However, the statistical analysis including the post-study period did not show a significant effect. The 305-day simulated milk production was higher for the YS group (+400 kg/cow) but again the difference was not significant. In conclusion, YS at a target dose of 5 × 107 CFU/kg DM improved milk production and milk quality in healthy dairy cows. In addition, when the data were included in a whole-farm model, feeding YS reduced methane emissions by 4%, reduced the number of animals required for the desired milk production by 4% and increased overall farm margins by 1.4%.

  • Influence of teat flow rate in commercial milk feeding systems on calf digestion and performance

  • R. McInnes, D. McInnes, R. Papworth, A. McIntyre
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    22 September 2015, e11
    Print publication:
    2015

  • Seventy two, one day old Friesian heifer calves were fed whole milk either via regular or slow release teats on commercial calfeteria systems (Milkbar, McInnes Manufacturing Limited, Waipu, New Zealand) for 42 days. For the entire period, the consumption time for the calves fed on the regular flow rate teat calfeterias was twice as fast as for those fed using the slow teats. Meal intake was numerically higher for the calves fed milk using the slow teats. At day 42, calves on the slow teats had a strong trend towards higher daily gain. At 14 days of age, visual differences in curding were seen in the abomasum of culled calves, with the fast teat-fed animals having large lumps of curded milk surrounded by watery liquid, whereas the slow teat-fed calves had much smaller particle sized curding in thicker fluid. Lactose digestion in the stomach was significantly higher for the calves fed using the slow teats, and there was a strong trend for higher levels of free protein in the ileum. Using slow flow rate teats to feed calves from day old to weaning appears to have an important impact on digestive processes in the immature gut. Such improvements in digestion and rumen development in young calves may assist in the digestion of milk and other feeds, leading to improved growth performance. Under farm conditions, slow release teat systems may reduce scours and other digestive problems in young calves during peak milk intake (up to 15 d of age), due to increased ileal digestion of nutrients, preventing undigested nutrient flow to the hind gut. It may also reduce cross-sucking behaviour in calves, which is undesirable.

  • The effects of differing proportions of dietary macronutrients on the digestibility and post-prandial endocrine responses in domestic cats (Felis catus)

  • S.R. Hill, K.J. Rutherfurd-Markwick, G. Ravindran, D.G. Thomas
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    30 March 2015, e4
    Print publication:
    2015

  • The aim of this study was to compare the effects of feeding two diets with different macronutrient proportions (high protein, low carbohydrate and low protein, high carbohydrate) on the digestibility and post-prandial endocrine responses of cats fed at maintenance levels, and to evaluate the effectiveness of the marginal ear vein prick technique for the measurement of blood glucose levels in feline studies. Two diets were fed to 16 adult domestic short-haired cats for a period of three weeks (eight cats per diet). Following a seven-day dietary adaptation period, the apparent macronutrient digestibility of the two diets was determined (days 8-19) using the total faecal collection method. The faeces were freeze dried, ground and analysed for dry matter, crude protein, crude fat and gross energy and then apparent digestibility was calculated. On days 20 and 21, the post-prandial glucose responses of the cats fed a single meal of one of the two diets were measured in serial blood samples collected using the marginal ear vein prick technique.

    Results showed that the high protein, low carbohydrate diet had higher (p < 0.05) apparent digestibility of dry matter, crude protein, crude fat and energy, lower (p < 0.01) daily faecal output and smaller fluctuations in blood glucose concentrations. Despite the two groups of cats having similar calorific intakes, the cats fed the high protein diet lost weight over the study period, whereas those fed the high carbohydrate, low protein diet gained weight. The marginal ear vein prick technique proved to be an effective alternative to catheterisation for blood glucose determination. The high protein diet tested in the current study, in addition to being more aligned to the cat's natural carnivorous diet, may be beneficial for weight management and blood glucose control in cats.

  • Tyrosine supplementation and hair coat pigmentation in puppies with black coats – A pilot study

  • Adrian Watson, Eric Servet, Marta Hervera, Vincent C. Biourge
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    22 September 2015, e10
    Print publication:
    2015

  • The appearance of a red hue to the hair in black coated cats and dogs has previously been reported as a “red hair syndrome”. Such changes in hair colour are related to an alteration in the proportions of two types of pigments produced by melanocytes; black eumelanin and brown pheomelanin. In black cats, it has been demonstrated that higher levels of phenylalanine + tyrosine (Phe+Tyr) than those recommended for growth are required to support eumelanin synthesis. The purpose of this study was to evaluate if a similar observation could be made in dogs. Twelve black coated puppies (Black Labrador retrievers and Newfoundlands) were divided into 3 groups of 4 and fed 3 diets with increasing concentrations of Phe+Tyr (A: 4 g/Mcal; B: 5.8 g/Mcal; C: 7 g/Mcal) for a period of 6 months. Quantification of plasma amino acids (Phe, Tyr, Cys) and spectrocolourimetry of hair samples from the Labrador retrievers (as the a* dimension of CIE Lab system) were performed at the beginning, during and at the end of the study. There was a significant negative linear relationship between plasma Tyr levels and a* values of hair in Labrador dogs on diets A and B, suggesting that a diet with total Phe+Tyr content of 6 g/Mcal (higher than the growth recommended allowance) was necessary to ensure an optimal black coat colour in these puppies and that levels up to 7 g/Mcal can lead to a more intense black coat colour. Moreover, similar to what was found in kittens, plasma levels of Tyr up to 54 μmol/l did not guarantee an optimal black colour coat and led to the “reddish hair” appearance in black coated puppies.

  • Validation of an Analytical Method for the Determination of the Activity of Xylanase in Animal Feed Additives and in Animal Feedingstuffs

  • G.P. Dillon, K. Filer, M. Gaffney, C.A. Moran
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    27 March 2015, e3
    Print publication:
    2015

  • Exogenous carbohydrases are commonly added to monogastric feed to help degrade non-starch polysaccharides (NSP). This action can increase the nutrient availability of feedingstuffs and decrease digestive disturbances, thus improving animal performance. This in turn can lead to improved feed conversion efficiency in meat and egg production. In light of the benefits associated with dietary xylanase inclusion, so too has it become increasingly relevant to quantity them in poultry feed premixtures with additional enzyme activities and directly in compound feed. Hitherto, the analysis of the activity of xylanase in animal feeds has proved difficult. Despite the widespread acceptance of the DNS method for the quantification of xylanase activity, it is not without limitations which can lead to erroneous under- or over-estimation of activity, and is particularly variable depending on the feed matrix wherein it is measured. The current method validation examined the following parameters: linearity, precision, uncertainty, sensitivity (limit of detection and limit of quantification) and the experiments were designed to highlight any interference from protease co-ingredients and possible matrix effects in various types of supplemented feed. The assay method described is convenient and inexpensive and could be applied to the rapid and routine analysis of xylanases in animal feeds during quality control and in investigating fraudulent adulteration of feed to ensure the authenticity and traceability of the product.

  • A Dual-enzyme Product Containing Protease in Broiler Diet: Efficacy and Tolerance

  • A. Kocher, J.M. Hower, C.A. Moran
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    28 April 2015, e6
    Print publication:
    2015

  • Exogenous enzymes are commonly added to poultry diets to improve nutrient utilisation, reduce excretion of nutrients into the environment as well as to improve zootechnical performance and reduce the cost of production. A series of four experiments were conducted in broilers to determine the efficacy and tolerance to an enzyme product (Vegpro™) containing protease and xylanase activities in wheat-soybean meal (SBM) diets fed to broilers from 1 to 39 or 42 d of age. Collectively, four experiments tested the following exogenous protease activity levels in wheat-SBM diet at levels of 0, 2,500, 5,000, 10,000, 20,000, 30,000, 40,000 or 100,000 HUT/kg of feed. Analysis of the four experiments together confirmed that Vegpro™ improved average daily gain and feed conversion ratio, especially in birds up to 21 d of age. Overall, inclusion of Vegpro™ to broiler diets at 10,000 HUT protease per kg of feed was shown to provide the maximum performance benefit (i.e. weight gain and feed conversion ratio). An exceptionally high protease activity (100,000 HUT/kg, ten times the manufacturer's recommended inclusion rate) was well tolerated and did not adversely affect the measured health and performance indicators from 1 to 42 d of age.

  • Preliminary evaluation of the efficacy of SteadfastTM Joint Supplement in captive exotic felids (Arabian leopard and cheetah)

  • Jane Budd, Ellen S. Dierenfeld, Katherine Whitehouse-Tedd
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    30 March 2015, e5
    Print publication:
    2015

  • Feline degenerative joint disease causes pain and disability and therefore represents a welfare concern for captive animals. Alternatives to traditional pharmaceutical therapies are gaining popularity and this study aimed to evaluate the efficacy of an egg-shell membrane therapy in captive cheetahs and leopards. Seven animals were treated with SteadfastTM and monitored for radiographic changes (n = 6) and lameness score (n = 7) over a 42 day period. A reduction in lameness was determined over the course of the study (p = 0.01), and improved orthopaedic status detected in 50% (3/6) of animals via radiographic examination. Surprisingly, a negative dose response was detected, whereby animals receiving lower doses exhibited the most marked changes in lameness score. Despite the small sample size and subjective scoring of lameness, this preliminary study demonstrates the need for further investigation into the use of an eggshell membrane-based supplement to improve mobility in captive felids with degenerative joint disease.

  • Natural resin acid –enriched composition as a modulator of intestinal microbiota and performance enhancer in broiler chicken

  • H. Kettunen, J. Vuorenmaa, T. Rinttilä, H. Grönberg, E. Valkonen, J. Apajalahti
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    04 March 2015, e2
    Print publication:
    2015

  • Resin acids extracted from coniferous trees are known for their antimicrobial and antifungal effects. This trial investigated the effect of a natural resin acid-enriched composition (RAC) on the gastrointestinal microbiota and productive performance of broiler chicken. The results demonstrated that at or above 5 mg/l, RAC prevented the growth of a pure culture of Clostridium perfringens, a causative agent of necrotic enteritis in poultry. Next, the effects of RAC on the microbial community were studied in a fermentation model with both the microbial inoculum and substrate for the microbes isolated from the ileum of broiler chickens. RAC was included at 0, 0.1 and 1 g/kg digesta, and supplementation decreased the relative proportion of lactic acid and increased that of acetic acid produced during the fermentation in a dose-dependent manner. At 1 g/kg inclusion, RAC decreased the density of lactobacilli. The final part of the experiment investigated the influence of RAC on the performance and intestinal microbiota of necrotic enteritis (NE)-challenged broiler chickens. A wheat and soy -based diet was supplemented with RAC at 0, 0.5, 1 and 3 g/kg. The chickens were challenged with Eimeria maxima oocysts on day 11, and a pure culture of C. perfringens on day 14. On day 17, the final day of the trial, RAC inclusion at 1 and 3 g/kg of feed significantly increased body weight. At 3 g/kg RAC numerically decreased the daily mortality seen during the challenge period. In the ileum, RAC at 1 g/kg reduced the NE-associated peak of microbial lactic acid production. Overall, the data suggested that the dietary ingredient RAC has the potential to act as a performance-enhancer and microbial modulator in broiler chickens.

  • Validation of an Analytical Method for the Determination of the Activity of Protease in Animal Feed Additives and in Animal Feedingstuffs

  • G.P. Dillon, K. Filer, C.A. Moran
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    23 January 2015, e1
    Print publication:
    2015

  • The nutrient availability in animal feeds can be improved by including exogenous enzymes to the feed, either by helping breakdown anti-nutritional factors or by increasing digestibility of complex ingredients thereby releasing more nutrients for utilisation. This process can improve the efficiency of meat and egg production, increase animal health, decrease feeding costs and reduce nutrients in animal waste. Proteases are protein-digesting enzymes that are used in animal nutrition to break down storage proteins in various plant materials and proteinaceous anti-nutrients in vegetable proteins. The analysis of exogenous proteases in feed additives and after they have been added to feed has proven technically challenging. Accordingly, the purpose of this work was to validate a method for the determination of the activity of protease in animal feed additives and supplemented animal feed. The approach used for the assay was to adapt an assay based on the hydrolysis of haemoglobin. The method validations examined a range of parameters including; linearity & range; uncertainty, sensitivity, accuracy and studies designed to highlight any possible matrix effects on various types of supplemented feed. The assay method described herein is convenient and inexpensive and could be applied to the analysis of proteases in animal feeds during quality control and in investigating fraudulent adulteration of feed to ensure the authenticity and traceability of the product.

  • A review of 733 published trials on Bio-Mos®, a mannan oligosaccharide, and Actigen®, a second generation mannose rich fraction, on farm and companion animals.

  • P. Spring, C. Wenk, A. Connolly, A. Kiers
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    20 May 2015, e8
    Print publication:
    2015

  • Mannan-oligosaccharides (MOS), as zootechnical feed ingredients, are widely used in animal nutrition. MOS has been commercially available since the launch of Bio-Mos® in the early 1990's and has a substantial body of scientific papers and practical examples of its efficacy. Since 1999, the use of MOS in animal feed has become more prominent, mainly due to the European ban on prophylactic antibiotic growth promoters in animal feed. MOS, with its ability to bind and limit the colonisation of gut pathogens, has proven to be an effective solution for antibiotic-free diets, as well as providing support for immunity and digestion. MOS has been shown to improve gastrointestinal health, thus improving wellbeing, energy levels and performance. Most MOS products, particularly those that have been scientifically developed, derive from the cell wall of the yeast, Saccharomyces cerevisiae. In 2009, a mannose-rich fraction (MRF) product was commercially launched as a ‘second generation’ of these MOS-type products, with enhanced activities in immune modulation and intestinal health. The purpose of this paper is to review the existing data on the benefits of MOS for all species of animals, discuss its mechanisms of action in vivo and compare the benefits of using second generation MRF to original MOS.

  • A comparative assessment of the fatty acid profiles and antioxidant status of supermarket eggs

  • Mark Gaffney, Rachel O'Rourke, Jules Taylor-Pickard, Richard Murphy
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    07 August 2015, e9
    Print publication:
    2015

  • Nutrient deposition in eggs is largely dictated by the dietary composition of laying hen feed, particularly in terms of specific fatty acids and antioxidants. In the present study, the nutritional quality of a range of commercially available egg varieties, marketed as omega-3 enriched; corn-fed; free range and standard caged, were assessed by determining fatty acid profiles and antioxidant status. Across each egg variety, significant differences were observed in key fatty acids such as palmitic, oleic, linoleic, alpha-linolenic and docosahexaenoic acid (DHA) (P ≤ 0.05). Egg yolks enriched with a stated dietary source of omega-3 fatty acid DHA were shown to have significantly improved levels of DHA (P ≤ 0.05), approximately 4.5-fold higher than standard caged eggs. Compared with free range, corn fed and caged, eggs from diets enriched with a source of omega-3 were shown to have considerably altered omega-6: omega-3 ratios, amounting to 1.5–2.1 fold reductions. Yolk antioxidant activity was improved for omega-3 enriched eggs, particularly in hexane fractionated samples. The inclusion of omega-3 fatty acids to the diet resulted in eggs with improved DHA contents and antioxidant status, highlighting the importance of poultry diet composition for egg nutritional quality.

  • Effect of a processed soy protein product on growth and gut physiology of broiler chickens

  • S.S.M. Beski, P.A. Iji
  • Journal:
    Journal of Applied Animal Nutrition / Volume 3 / 2015
    Published online by Cambridge University Press:
    11 May 2015, e7
    Print publication:
    2015

  • A 4 × 2 factorial experiment was conducted to investigate the effect of a processed soy protein (PSP) on broiler performance and digestive physiology. Four inclusion levels of PSP (0, 25, 50 or 100 g/kg in either corn or wheat-based diets) were used in the starter diets. Feed intake was significantly lower (P < 0.01) on corn-based diets than those on wheat-based diets at 35 d. Over the first 10 d, chicks on corn-based diets tended (P < 0.09) to have higher body weight (BW) than wheat-based diet chicks. Across the 35 d trial, PSP level showed a strong tendency (P < 0.06) to be related to higher BW in birds, regardless of grain type. Both grain and PSP experimental factors significantly (P < 0.01, and P < 0.001) interacted at an early age, improving BW and feed conversion ratio (FCR) for birds received high PSP on wheat-based diets. Significantly heavier (P < 0.01) small intestine and gizzard + proventriculas weights at an early age, and heavier (P < 0.001) gizzard + proventriculas and pancreas during the grower stage were recorded in birds fed the corn-based diets. At 24 d, pancreatic chymotrypsin amidase and lipase enzymes were significantly (P < 0.01) more active in chickens fed the wheat-based diet. The interaction of PSP level and the type of the grain was significant (P < 0.01) for pancreatic chymotrypsin amidase and lipase as well as jejunal maltase (P < 0.05). Both experimental factors had a significant influence on jejunum histomorphology at 24 d of age (P < 0.001). There was a significant interaction between level of PSP and the type of grain (P < 0.05) resulting in the highest villus surface areas being seen for birds fed the corn-based diet and receiving the medium level of PSP. The trial demonstrated that PSP supplement can be included at between 50 and 100 g/kg of starter diets, depending on the basal diet.

  • 14 - Clinical applications

  • C. Mauli Agrawal, University of Texas, San Antonio, Joo L. Ong, University of Texas, San Antonio, Mark R. Appleford, University of Texas, San Antonio, Gopinath Mani, University of South Dakota
  • Book:
    Introduction to Biomaterials
    Published online:
    01 February 2019
    Print publication:
    07 November 2013, pp 375-398

  • Summary

    Goals

    After reading this chapter, students will understand the following.

  • Advantages of different biomaterials used in clinical applications.

  • Rationale for use of the different biomaterials in clinical applications.

  • Role of biomedical engineers in medicine.

    • In today’s healthcare industry, synthetic and natural biomaterials are being introduced into the human body at an increasing rate. In the United States alone, several million biomaterial-based implants or devices are used for human patients each year. It is not uncommon to find that many of the biomaterials used today were first introduced for industrial applications other than medicine. In order to protect and promote public health, all biomaterials used by the medical device industry have to meet numerous stringent criteria required by regulatory agencies such as the Food and Drug Administration in the USA. These stringent criteria include material properties, preparation and sterilization of the materials, biocompatibility, and short-term and long-term issues related to the use of the material for a specific application. With these protections in place, reasons for the conventional use of biomaterials in clinics and hospitals include:

  • treating in order to return to normalcy,

  • repairing in order to reinstate organ function, and

  • restoring in order to retain or modify organ shape or form.

  • 5 - Metals: structure and properties

  • C. Mauli Agrawal, University of Texas, San Antonio, Joo L. Ong, University of Texas, San Antonio, Mark R. Appleford, University of Texas, San Antonio, Gopinath Mani, University of South Dakota
  • Book:
    Introduction to Biomaterials
    Published online:
    01 February 2019
    Print publication:
    07 November 2013, pp 113-133

  • Summary

    Goals

    After reading this chapter the student will understand the following.

  • Structure and properties of metals commonly used for making biomedical implants and devices.

  • Use of different metals as biomaterials.

    • Metals are extensively used as materials for biomedical implants, devices, and surgical tools. Some of the implants made from metals are shown in Figure 5.1. For example, metals are used for orthopedic reconstructions (implants for artificial hip, knee, shoulder, and elbow joints), fracture fixation (plates, pins, screws, rods, and nails), oral and maxillofacial reconstructions (dental implants and mini-plates), and cardiovascular interventions (stents, heart valves, and pacemakers). In general, metals used for biomedical applications should exhibit the following properties:

  • high corrosion resistance,

  • biocompatibility,

  • high wear resistance,

  • excellent mechanical properties.

    • Most metallic biomaterials have a stable surface oxide layer that enhances their corrosion resistance properties. It is believed that the presence of this stable surface oxide layer is key to the biocompatibility of metals. The mechanical properties of the metal are important and should satisfy the requirements of the specific application in the body. For instance, when a metal is used to augment a bone, the elastic modulus of the metal should be ideally equivalent to that of the bone. If the elastic modulus of the metal is greater than that of bone, then the load experienced by the bone is reduced due to a phenomenon known as stress shielding. This can cause the bone to remodel to adjust to the lower load and eventually result in the loss of bone quality. In another example, stainless steel is commonly used for making coronary stents due to its well-suited mechanical properties. Stainless steel has good radial strength (due to its high elastic modulus of ~190 GPa), low recoil, good expandability, and sufficient flexibility, which makes it a highly preferred metal for making stents. Several metals such as titanium, stainless steel, cobalt–chromium alloys, nitinol (nickel–titanium alloy), tantalum, and magnesium have been used for a variety of clinical applications, with titanium, stainless steel, and cobalt–chromium alloys being the most commonly used metals. This chapter describes the structure and properties of these metals.

  • 1 - Introduction

  • C. Mauli Agrawal, University of Texas, San Antonio, Joo L. Ong, University of Texas, San Antonio, Mark R. Appleford, University of Texas, San Antonio, Gopinath Mani, University of South Dakota
  • Book:
    Introduction to Biomaterials
    Published online:
    01 February 2019
    Print publication:
    07 November 2013, pp 1-18

  • Summary

    Goals

    After reading this chapter the student will understand the following.

  • History of implants and biomaterials.

  • Various definitions for biomaterials.

  • Different types of chemical bonds.

  • Basic families of materials.

  • Future directions for the progress in biomaterials.

    • The Rig Veda, one of the four sacred Sanskrit books of ancient India that were compiled between 3500 and 1800 BC, relates the story of a warrior queen named Vishpla, who lost a leg in battle and was fitted with an iron leg after the wound healed. There is also mention of lacerated limbs treated with sutures. Sushruta, a renowned Indian physician from circa 600 BC, wrote a very comprehensive treatise describing various ailments as well as surgical techniques. His technique for nose reconstruction using a rotated skin flap is still used in modern times. Sutures made of vegetable fibers, leather, tendons, and horse hair were commonly used in his time. There are also reports of the use of linen sutures in Egypt 4000 years ago.

    These ancient records show that, since time immemorial, humans have tried to restore the function of limbs or organs that have ceased to perform adequately due to trauma or disease. Often, this was attempted through the use of materials either made or shaped by humans and used external to the body. These were the earliest form of biomaterials. Although examples of successful external prosthetic devices can be found in history, materials placed inside the body, also known as implants, were usually not viable due to infection. This changed in the 1860s with the advent of aseptic surgical techniques introduced by Dr. J. Lister. The discovery of antibiotics in the mid 1900s also reduced the incidence of infections related to surgery. Today, implants are very successful and are used in a wide variety of applications in the practice of medicine, improving the quality of life for millions and saving countless lives. However, the successes of today have come after a long history of trial and error and scientific endeavor.

  • 9 - Surface modification

  • C. Mauli Agrawal, University of Texas, San Antonio, Joo L. Ong, University of Texas, San Antonio, Mark R. Appleford, University of Texas, San Antonio, Gopinath Mani, University of South Dakota
  • Book:
    Introduction to Biomaterials
    Published online:
    01 February 2019
    Print publication:
    07 November 2013, pp 233-281

  • Summary

    Goals

    After reading this chapter, students will understand the following.

  • Main categories of the different surface modification techniques commonly used to engineer biomaterial surfaces.

  • Principles underlying these surface modification techniques.

  • Advantages and limitations of each technique.

    • Despite the advent of advanced manufacturing tools and newly developed materials with unique properties, why is the attention of biomedical scientists and engineers focused on biomaterial surfaces? Unlike the material’s bulk, which generally governs the mechanical integrity of medical devices, the material’s surface governs tissue–biomaterial interactions and these usually occur within a narrow depth of less than 1 nm on the material’s surface. Surface modification of biomaterials allows the tailoring of surface properties without affecting bulk material properties. These altered surface properties influence tissue–biomaterial interactions, which ultimately determine the success or failure of a device placed in the human body. In addition to improving tissue–biomaterial interactions, modification of biomaterial surfaces may also be performed for the purpose of improving surface mechanical properties such as wear resistance. This can be achieved through surface or subsurface alloying, or heat treatment. Enhancement of surface oxide thickness or the presence of a dense protective coating on a metallic surface can provide surface barriers which minimize the metal’s chemical reactions with its surroundings, thereby improving its corrosion resistance. Thus, through surface modification, the native surfaces of biomaterials can be physically or chemically transformed with the primary goal of engineering desired surface chemistry, topography, reactivity, biocompatibility, hydrophilicity, or charge.

  • 4 - Characterization of biomaterials

  • C. Mauli Agrawal, University of Texas, San Antonio, Joo L. Ong, University of Texas, San Antonio, Mark R. Appleford, University of Texas, San Antonio, Gopinath Mani, University of South Dakota
  • Book:
    Introduction to Biomaterials
    Published online:
    01 February 2019
    Print publication:
    07 November 2013, pp 74-112

  • Summary

    Goals

    After reading this chapter the student will understand the following.

  • The principles underlying various instruments typically used for the characterization of biomaterials.

  • The use of different instruments for biomaterials characterization.

    • During the development phase of any medical devices or implants, it is essential that the biomaterials used are thoroughly characterized. The material’s surface properties are important because it is the implant’s surface where the body’s biology and the material first interact. On the other hand, the bulk properties of the material determine its mechanical and physical behavior and its long-term viability. Of course, the material’s chemical properties influence its stability, biocompatibility, and the body’s reaction to it. Since a material possesses different physical and chemical properties, the analytical instruments used for characterizing these properties can be broadly classified under the following three categories:

  • surface characterization,

  • bulk characterization, and

  • chromatographic analysis.

    • The use of multiple characterization techniques is essential for complete analysis of the surface and bulk properties of a biomaterial. When a material is implanted in the body, protein adsorption almost instantaneously occurs on the material surface. Hence, the cells do not directly interact with the material surface but only through the layer of proteins adsorbed on the surface. This adsorption of proteins is governed by a combination of different surface characteristics of the material including surface energy, surface chemistry, surface texture, and surface roughness. The use of contact angle measurement provides information about the material’s surface energy, whereas Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS) provide information on the material’s surface chemistry at different depths. Scanning electron microscopy (SEM) provides details about the material’s surface texture, whereas atomic force microscopy (AFM) allows for measurement of the material’s surface roughness. Thus, data collection using different analytical instruments provides in-depth information regarding the material’s surface and assists in predicting how surface properties would influence the biological outcome.

  • 12 - Drug delivery systems

  • C. Mauli Agrawal, University of Texas, San Antonio, Joo L. Ong, University of Texas, San Antonio, Mark R. Appleford, University of Texas, San Antonio, Gopinath Mani, University of South Dakota
  • Book:
    Introduction to Biomaterials
    Published online:
    01 February 2019
    Print publication:
    07 November 2013, pp 321-340

  • Summary

    Goals

    After reading this chapter the student should understand the following.

  • The fundamentals and importance of drug delivery systems.

  • How various different types of controlled drug delivery systems work.

    • Therapeutic drugs play a significant role in the therapy of almost all medical problems. From the treatment of common ailments such as headaches, and colds, to the reduction of fever, fighting infection, reducing cholesterol and blood pressure, and treating cancer, drugs play a major role in medicine. The systems used for delivering drugs take on a variety of forms. These include simple oral systems such as tablets, capsules, and syrups, transdermal systems like ointments and patches, and intravenous delivery using suspensions or nanoparticles.

    In order for a drug to provide a therapeutic effect, the concentration of the drug in the blood plasma has to be above the minimum effective level and below the level that may be toxic. The difference between the minimum effective level and the toxic level is called the therapeutic index. As shown in Figure 12.1a, when the drug is conventionally administered as a single dose and is metabolized quickly inside the body, the level of drug in the blood plasma immediately increases followed by an exponential decrease. In such a conventional administration of the drug, the time frame over which the drug concentration is above the minimum effective level may not be long enough to produce a significant therapeutic effect in a single dose. Although this situation can be improved by increasing the amount of dose, this quickly raises the drug level to the toxic region. The alternative is to administer doses at regular intervals (Figure 12.1b). However, this method too has limitations, such as:

  • the drug level in blood plasma is irregular and fluctuates with a high ratio of peak-tovalley concentrations, and

  • the patient compliance is often poor.

  • 6 - Polymers

  • C. Mauli Agrawal, University of Texas, San Antonio, Joo L. Ong, University of Texas, San Antonio, Mark R. Appleford, University of Texas, San Antonio, Gopinath Mani, University of South Dakota
  • Book:
    Introduction to Biomaterials
    Published online:
    01 February 2019
    Print publication:
    07 November 2013, pp 134-164

  • Summary

    Goals

    After reading this chapter the student will understand the following.

  • Structure of polymers and their common physical states.

  • General properties of polymers.

  • Common types of polymerization techniques used for production.

  • Chemical structure and properties of common biomedical polymers.

  • Structure of hydrogels and their general properties.

  • Definition and uses of nanopolymers.

    • In everyday life, we encounter a variety of polymers, some natural and others synthetic. The vast majority of these are carbon-based in nature. They range from synthetic polymers seen in products such as polyethylene grocery bags, polymethylmethacrylate-based window panes, and polystyrene-based eating utensils, to natural polymers such as starch, cellulose and rubber. Polymers used as biomaterials are often similar to these common materials. For example, the polymer most extensively used in total joint prostheses is ultrahigh molecular weight polyethylene – chemically identical to the material used for plastic bags, although having a much higher molecular weight. The same is true for bone cement which is used in conjunction with bone surgery and Plexiglass®, which is used for window panes. Both of these materials are polymethylmethacrylate (PMMA). Of course, any polymer that is used as an implant has to meet strict safety standards as required by governmental and other regulatory agencies and has to be virtually contaminant free.

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