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- By Aakash Agarwala, Linda S. Aglio, Rae M. Allain, Paul D. Allen, Houman Amirfarzan, Yasodananda Kumar Areti, Amit Asopa, Edwin G. Avery, Patricia R. Bachiller, Angela M. Bader, Rana Badr, Sibinka Bajic, David J. Baker, Sheila R. Barnett, Rena Beckerly, Lorenzo Berra, Walter Bethune, Sascha S. Beutler, Tarun Bhalla, Edward A. Bittner, Jonathan D. Bloom, Alina V. Bodas, Lina M. Bolanos-Diaz, Ruma R. Bose, Jan Boublik, John P. Broadnax, Jason C. Brookman, Meredith R. Brooks, Roland Brusseau, Ethan O. Bryson, Linda A. Bulich, Kenji Butterfield, William R. Camann, Denise M. Chan, Theresa S. Chang, Jonathan E. Charnin, Mark Chrostowski, Fred Cobey, Adam B. Collins, Mercedes A. Concepcion, Christopher W. Connor, Bronwyn Cooper, Jeffrey B. Cooper, Martha Cordoba-Amorocho, Stephen B. Corn, Darin J. Correll, Gregory J. Crosby, Lisa J. Crossley, Deborah J. Culley, Tomas Cvrk, Michael N. D'Ambra, Michael Decker, Daniel F. Dedrick, Mark Dershwitz, Francis X. Dillon, Pradeep Dinakar, Alimorad G. Djalali, D. John Doyle, Lambertus Drop, Ian F. Dunn, Theodore E. Dushane, Sunil Eappen, Thomas Edrich, Jesse M. Ehrenfeld, Jason M. Erlich, Lucinda L. Everett, Elliott S. Farber, Khaldoun Faris, Eddy M. Feliz, Massimo Ferrigno, Richard S. Field, Michael G. Fitzsimons, Hugh L. Flanagan Jr., Vladimir Formanek, Amanda A. Fox, John A. Fox, Gyorgy Frendl, Tanja S. Frey, Samuel M. Galvagno Jr., Edward R. Garcia, Jonathan D. Gates, Cosmin Gauran, Brian J. Gelfand, Simon Gelman, Alexander C. Gerhart, Peter Gerner, Omid Ghalambor, Christopher J. Gilligan, Christian D. Gonzalez, Noah E. Gordon, William B. Gormley, Thomas J. Graetz, Wendy L. Gross, Amit Gupta, James P. Hardy, Seetharaman Hariharan, Miriam Harnett, Philip M. Hartigan, Joaquim M. Havens, Bishr Haydar, Stephen O. Heard, James L. Helstrom, David L. Hepner, McCallum R. Hoyt, Robert N. Jamison, Karinne Jervis, Stephanie B. Jones, Swaminathan Karthik, Richard M. Kaufman, Shubjeet Kaur, Lee A. Kearse Jr., John C. Keel, Scott D. Kelley, Albert H. Kim, Amy L. Kim, Grace Y. Kim, Robert J. Klickovich, Robert M. Knapp, Bhavani S. Kodali, Rahul Koka, Alina Lazar, Laura H. Leduc, Stanley Leeson, Lisa R. Leffert, Scott A. LeGrand, Patricio Leyton, J. Lance Lichtor, John Lin, Alvaro A. Macias, Karan Madan, Sohail K. Mahboobi, Devi Mahendran, Christine Mai, Sayeed Malek, S. Rao Mallampati, Thomas J. Mancuso, Ramon Martin, Matthew C. Martinez, J. A. Jeevendra Martyn, Kai Matthes, Tommaso Mauri, Mary Ellen McCann, Shannon S. McKenna, Dennis J. McNicholl, Abdel-Kader Mehio, Thor C. Milland, Tonya L. K. Miller, John D. Mitchell, K. Annette Mizuguchi, Naila Moghul, David R. Moss, Ross J. Musumeci, Naveen Nathan, Ju-Mei Ng, Liem C. Nguyen, Ervant Nishanian, Martina Nowak, Ala Nozari, Michael Nurok, Arti Ori, Rafael A. Ortega, Amy J. Ortman, David Oxman, Arvind Palanisamy, Carlo Pancaro, Lisbeth Lopez Pappas, Benjamin Parish, Samuel Park, Deborah S. Pederson, Beverly K. Philip, James H. Philip, Silvia Pivi, Stephen D. Pratt, Douglas E. Raines, Stephen L. Ratcliff, James P. Rathmell, J. Taylor Reed, Elizabeth M. Rickerson, Selwyn O. Rogers Jr., Thomas M. Romanelli, William H. Rosenblatt, Carl E. Rosow, Edgar L. Ross, J. Victor Ryckman, Mônica M. Sá Rêgo, Nicholas Sadovnikoff, Warren S. Sandberg, Annette Y. Schure, B. Scott Segal, Navil F. Sethna, Swapneel K. Shah, Shaheen F. Shaikh, Fred E. Shapiro, Torin D. Shear, Prem S. Shekar, Stanton K. Shernan, Naomi Shimizu, Douglas C. Shook, Kamal K. Sikka, Pankaj K. Sikka, David A. Silver, Jeffrey H. Silverstein, Emily A. Singer, Ken Solt, Spiro G. Spanakis, Wolfgang Steudel, Matthias Stopfkuchen-Evans, Michael P. Storey, Gary R. Strichartz, Balachundhar Subramaniam, Wariya Sukhupragarn, John Summers, Shine Sun, Eswar Sundar, Sugantha Sundar, Neelakantan Sunder, Faraz Syed, Usha B. Tedrow, Nelson L. Thaemert, George P. Topulos, Lawrence C. Tsen, Richard D. Urman, Charles A. Vacanti, Francis X. Vacanti, Joshua C. Vacanti, Assia Valovska, Ivan T. Valovski, Mary Ann Vann, Susan Vassallo, Anasuya Vasudevan, Kamen V. Vlassakov, Gian Paolo Volpato, Essi M. Vulli, J. Matthias Walz, Jingping Wang, James F. Watkins, Maxwell Weinmann, Sharon L. Wetherall, Mallory Williams, Sarah H. Wiser, Zhiling Xiong, Warren M. Zapol, Jie Zhou
- Edited by Charles Vacanti, Scott Segal, Pankaj Sikka, Richard Urman
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- Book:
- Essential Clinical Anesthesia
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- 05 January 2012
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- 11 July 2011, pp xv-xxviii
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The protozoa occurring in the hind-gut of cockroaches. III. Factors affecting the dispersion of Nyctotherus ovalis
- H. M. D. Hoyte
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- Journal:
- Parasitology / Volume 51 / Issue 3-4 / November 1961
- Published online by Cambridge University Press:
- 06 April 2009, pp. 465-495
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The only mode of transmission of Nyctotherus ovalis from one cockroach to another was shown experimentally to be by way of ingestion of the encysted stage of the ciliate. The cysts were remarkably resistant, being able to remain viable for 21 weeks at −18°C. if kept in dry faeces, or for 20 weeks in wet faeces at 4°–25°C. Their life was much shorter if kept at 37°, 25°, or 4°C. under dry conditions, or at −18°C. under wet. The cysts could withstand freeze-drying, or storage in pure oxygen, carbon dioxide or nitrogen, at least for short periods.
Nyctotherus ovalis could excyst in any of the four species of cockroach which were tested (Periplaneta americana, Blatta orientalis, Blattella germanica, Blaberus giganteus), irrespective of the species of origin. The ciliate could establish an infection in a very young host; in a host which had ingested infected faeces once only; in hosts which were in a very dry or a very humid environment; in a host maintained at a temperature far below that required for in vitro excystation, subject only to the temperature being high enough for it to be possible for the cockroach to digest its meal; but Nyctotherus could not establish an infection in cockroaches which were about to moult, because there was no movement nor digestion of food in the gut. There was no evidence of an instinctive drive on the part of the cockroach to eat infected faeces. There was some evidence that the Blatta and Blattella types of trophozoite and cyst were associated with the presence or absence respectively of a type of flora typically associated with the hind-gut of Blatta.
The process of excystation took as little as 3 hr. for completion in vivo, but this time was increased if faecal material was ingested along with cysts. The process was most rapid in the smallest cockroach (Blattella) and slowest in the largest (Blaberus). The process, once started, could be completed in vitro, but at a considerably slower pace. Digestion of the knob on the cyst by the cockroach's enzymes seemed to be necessary if the ciliate was to emerge.
A small proportion of cysts hatched after passage through the gut of a locust, but no means were found of increasing this proportion, and an infection was never established. Excystation did not occur in any other arthropod, nor in the frog, which were tested.
Cysts recovered from the mid-gut of a cockroach completed the process of excystation in vivo more rapidly if they were put in a buffer medium of pH approximating that of the mid-gut than if they were put in saline. Passage of the cysts through the foregut of the cockroach had no function in stimulating excystation: the agent seemed to be the trypsin secreted by the mid-gut caeca, or the products of its activity. The many failures in the series of experiments which are reported here can probably be attributed to contaminating bacteria.
The complete process of excystation could occur in vitro if the cysts were incubated with faecal matter from the cockroach. The optimum temperature was 32°C., and 2 days were needed for a significant number to hatch. No means were found of shortening this time, nor any agents which could be substituted for the faecal matter. The stimulus seemed to be provided by particular anaerobic bacteria of the faeces which were present in some cockroaches, but absent in others.
Work by other authors on excystation in other Protozoa is reviewed. It was concluded that in vivo excystation of Nyctotherus ovalis occurs as a result of stimulation of the cyst by the digestive trypsin of the cockroach, and not by the products of the unidentified bacterium which is active in vitro. Cysts originating from Blaberus seemed to be less sensitive to this bacterial factor than some of those from Periplaneta or Blatta.
This work was done during the tenure of a Research Studentship awarded by by the Agricultural Research Council. I am deeply indebted to Dr P. Tate for his encouragement and counsel at all stages of the work.
Eperythrozoon teganodes sp.nov. (Rickettsiales), parasitic in cattle
- H. M. D. Hoyte
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- Journal:
- Parasitology / Volume 52 / Issue 3-4 / November 1962
- Published online by Cambridge University Press:
- 06 April 2009, pp. 527-532
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Eperythrozoon teganodes is described from the blood of cattle. It is compared with, and is shown to be distinct from, E. wenyoni Adler & Ellenbogen, 1934. E. teganodes is a parasite of the plasma rather than of the erythrocyte. It occurs as fine rods and threads, rings, and rings with a rod or thread attached. (E. wenyoni adheres to the edge and the face of the erythrocyte, appearing as densely staining coccoids and faintly staining disks.) It is suggested that some highly polymorphic species of Eperythrozoon may prove to be a mixture of two or more species.
I wish to thank Professor J. F. A. Sprent for his advice and for criticizing the manuscript, and Messrs J. Ballantyne, C. Boel and F. Mellis for technical assistance. The photographs were taken by Mr E. Hollywood of the Photographic Department of the University of Queensland. I am grateful to Dr D. W. Brocklesby for allowing me to examine his material. This work was aided by facilities and funds provided by the Rural Credits Fund of the Reserve Bank of Australia, and by the Queensland Dairymen's Organization.
The protozoa occurring in the hind-gut of cockroaches: II. Morphology of Nyctotherus ovalis
- H. M. D. Hoyte
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- Journal:
- Parasitology / Volume 51 / Issue 3-4 / November 1961
- Published online by Cambridge University Press:
- 06 April 2009, pp. 437-463
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The size and shape of the trophozoite of Nyctotherus ovalis in different species of cockroaches was found to vary considerably, and this was attributed chiefly to the presence or absence of large paraglycogen granules within the ciliate.
The size and shape of the cysts of N. ovalis which were passed in the faeces of the host on successive days were found to fluctuate around means which were more or less constant over a long period. The constants varied according to the species of the host: the largest and fattest cysts were found in the faeces from Blatta, the smallest and most slender from Blattella. Those from Blaberus were of the Blattella-type, but Periplaneta harboured populations which gave rise either to the Blatta-type of cysts or to the Blattella-type.
The constant size and shape of the cysts was not altered when the host moulted, but there was always a decrease in size and sometimes a change of shape when an infection was established in a new host. The cause of these changes is unknown. An increase in size was induced by an increase in environmental temperature, but the size declined during a subsequent period at lower temperatures. The work of other authors on changes in the sizes of protozoan cysts is discussed.
The cyst wall of N. ovalis consists of four separate layers plus an outer membrane. They all seemed to be proteinaceous in nature. Treatment with various inorganic reagents and proteolytic enzymes revealed that the knob is the most easily destroyed part of the wall. A histochemical test for keratin showed that this is the chief constituent of the wall. The keratin appeared to be least organized in the knob, and hence the knob is the least impermeable part of the wall.
This work was done during the tenure of a Research Studentship awarded by the Agricultural Research Council. I am deeply indebted to Dr P. Tate for his encouragement and counsel at all stages of the work.
The protozoa occurring in the hind-gut of cockroaches. I. Responses to changes in environment
- H. M. D. Hoyte
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- Journal:
- Parasitology / Volume 51 / Issue 3-4 / November 1961
- Published online by Cambridge University Press:
- 06 April 2009, pp. 415-436
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Records of non-sporozoan Protozoa occurring in the hind-gut of cockroaches are summarized.
The Protozoa studied were the three flagellates Lophomonas striata, L. blattarum, Monocercomonoides orthopterorum; the rhizopod Endamoeba blattae, and the ciliate Nyctotherus ovalis, in the cockroaches Periplaneta americana, P. australasiae, Blatta orientalis, Blattella germanica and Blaberus giganteus.
Specimens of Blatta and Periplaneta americana were maintained at 37° and 25°C. under extreme conditions of humidity. Maximum humidity enabled the host, and the Nyctotherus which it harboured to survive for a longer time. The results of the experiments indicated that the well-being of the protozoan parasites is closely linked to that of the host.
Periplaneta americana, Blatta, Blatella and Blaberus were subjected to pure oxygen at 3½ atmospheres pressure and the effect on the Protozoa observed. The flagellates were killed first, then Endamoeba and lastly Nyctotherus. They survived in Blatta for a longer time than in Periplaneta; and Nyctotherus in Blaberus and Blattella sometimes survived the hosts. The hosts appeared to act as a barrier against poisoning by oxygen, and the strength of the barrier varied in the different species of cockroaches.
Nymphal Periplaneta or Blatta which were about to moult underwent a period of self-starvation which lasted for up to 10 days. The period was terminated by the moult: at this time, the little food that was in the gut was very dry. All species of Protozoa could survive these conditions, but Nyctotherus seemed to be the most hardy. The main mass of ciliates seemed to be nearer to the anus than in the non-moulting cockroach. Many of the ciliates were often clumped together into a ‘raspberry’. The bodies of the individual ciliates were more spherical than usual, but those in the ‘raspberry’ were moulded into polygonal shapes. The macronucleus underwent a change in form which revealed that its basic structure is that of a folded sheet.
The changes were reversed within 24 hr. They could not be induced by experimentally imposed conditions of starvation or dehydration of the hind-gut. The changes in Nyctotherus ovalis are contrasted with the sexual stages occurring in N. cordiformis and in the Protozoa of Cryptocercus.
This work was done during the tenure of a Research Studentship awarded by the Agricultural Research Council. I am deeply indebted to Dr P. Tate for his encouragement and counsel at all stages of the work. I wish to thank Drs J. Barker and E. R. Turner, of the Cambridge University Botany School, for the loan of the apparatus used in subjecting cockroaches to oxygen under pressure, and Mr A. C. Bloy, of the Zoology Department, for gifts of cockroaches. I am most grateful to Mrs E. F. M. Hawkins and Mr B. H. Baker for technical assistance.
Grahamella (Rickettsiales) in the common shrew Sorex araneus
- H. M. D. Hoyte
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- Journal:
- Parasitology / Volume 46 / Issue 1-2 / May 1956
- Published online by Cambridge University Press:
- 06 April 2009, pp. 224-234
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Nine out of thirty-three specimens of the common shrew Sorex araneus, caught at Rosta in north Norway in August 1953, were found to be infected with Grahamella (Rickettsiales). Nine specimens of Clethrionomys rutilus, nine of Microtus oeconomus ratticeps and one of M. agrestis, caught at the same time and place, were found to be free of Grahamella. No other blood parasites were found in any of the animals examined.
Records by other authors of Grahamella in a variety of hosts are reviewed. The parasite is known to occur in mammalian hosts only: identifications of it in non-mammalian hosts can be discarded. Host specificity, tacitly assumed by most authors, is not proven, and therefore most of the specific names bestowed on Grahamella in different hosts are of doubtful validity. The morphology of the parasite varies little from host to host; and there is little evidence to show that its pathogenic effect on any host is serious. Grahamella has been cultured by a few authors: variations in characters of these cultures may be more reliable criteria for recognition of different species of Grahamella.
These small mammals were collected while I was a member of the University of Edinburgh Expedition to Arctic Norway, 1953. I wish to thank all who were concerned, in particular Dr D. M. Steven, with whom I did the trapping. The rest of the work was done during the tenure of a Research Studentship awarded by the Agricultural Research Council. I also wish to thank Dr P. Tate for his advice and his criticisms of the manuscript.