Field experiments were conducted in 1996, 1997, and 1998 at Ste. Anne de Bellevue, Quebec, Canada, and in 1996 at Ottawa, Ontario, Canada, to quantify the impact of corn hybrids, differing in canopy architecture and plant spacing (plant population density and row spacing), on biomass production by transplanted and naturally occurring weeds. The treatments consisted of a factorial combination of corn type (leafy reduced stature [LRS], late-maturing big leaf [LMBL], a conventional Pioneer 3979 [P3979], and, as a control, a corn-free condition [weed monoculture]), two weed levels (low density [transplanted weeds: common lambsquarters and redroot pigweed] and high density [weedy: plots with naturally occurring weeds]), two corn population densities (normal and high), and row spacings (38 and 76 cm). At all site-years under both weed levels, the decrease in biomass production by both transplanted and naturally occurring weeds was greater due to the narrow row spacing than due to the high plant population density. The combination of narrower rows and higher population densities increased corn canopy light interception by 3 to 5%. Biomass produced by both transplanted and naturally occurring weeds was five to eight times less under the corn canopy than in the weed monoculture treatment. Generally, weed biomass production was reduced more by early-maturing hybrids (LRS and P3979) than by LMBL. Thus, hybrid selection and plant spacing could be used as important components of integrated pest management (weed control) for sustainable agriculture.

Glutamate excitotoxicity is implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS). We report the results of a double blind, placebo controlled, trial using 100 mg of oral daily lamotrigine (3,5-diamino-6-(2,3 dichlorophenyl)-l,2,4-triazine) which inhibits glutamate release. 67 patients were entered and at trial termination of 1.5 years 15 had withdrawn (9 active and 6 placebo) and 12 had died (6 active and 6 placebo). Mean age at entry was 57.5 years for the active and 58.6 years for the placebo groups. Patients were seen at 3 monthly intervals and scored according to neurological deficit based upon age of onset, bulbar and respiratory involvement, ambulation and functional disability. The mean change in clinical scores for the active versus placebo groups over the trial period was 7.1 ± 3.3 and 9.0 ± 3.3 respectively (0.05 < p < 0.10). Changes in cortical threshold and MEP/CMAP ratios to magnetic stimulation also did not differ significantly between the two groups. We conclude that lamotrigine in the doses administered does not alter the course of ALS.

Cucullia umbratica Linnaeus (Lepidoptera: Noctuidae), Agnippe prunifoliella Chambers (Lepidoptera: Gelechiidae), and Bryotropha plantariella Tengstrom (Lepidoptera: Gelechiidae), were significant bycatch in pheromone-based trapping systems for red-striped fireworm, Aroga trialbamaculella Chambers (Lepidoptera: Gelechiidae), in Nova Scotia, Canada. Cucullia umbratica is a European introduced species and a new macrolepidopteran recorded in continental Canada. The only previous record of this moth in North America was from the Magdalen Islands (Québec, Canada). Potential attractants for B. plantariella, A. prunifoliella, and C. umbratica are a result of this bycatch investigation.

The mycetophilid Macrocera nobilis Johnson, previously known only from forests in New Hampshire and Massachusetts, is here reported from caves in Oklahoma, Missouri, Kentucky, Tennessee, and West Virginia. A study of populations in Oklahoma shows that the short-lived adults mate in cave entrances, but that oviposition, larval development, and pupation occur only in the dark zone of caves. The larvae build extensive webs upon which they travel and which they use to capture insect prey (mostly other Diptera). Reproduction and life cycle development is not seasonal. The larval stage lasts 9 or 10 months, and the pupal stage about 2 weeks.

It will be convenient to summarise the results of the foregoing observations and the conclusions which appear justified by a comparison of results obtained by the two methods of standardisation under consideration, namely (1) cutaneous, on the human subject, and (2) intracutaneous (intradermal) on the guinea-pig.

1. In the absence of knowledge regarding the essential chemistry of tuberculin, a chemical method of standardisation is excluded.

2. The phenomena of allergic reactivity point to a biological basis for standardisation.

3. The allergic reactions have been studied in the sensitised animal and in the human tuberculised subject.

4. Tuberculins of unknown potency have been compared with a tuberculin of known potency which has been selected as standard.

5. Comparative observations have been made as between the standard and the unknown tuberculin, by (a) making use of different dilutions, and (6) assessing results in animals (sensitised) and in human (tuberculised) subjects.

6. In the sensitised guinea-pig the intracutaneous method has been used, and a definite procedure followed in the determination of results.

7. In the human tuberculised subject the cutaneous method has been used, and similar procedure followed for the determination of results. The method and results are illustrated in the text.

8. The results in the two sets of observations are definite and comparable. Both afford a basis for standardisation.

9. The average probable errors by the two methods are approximately equal, that is, the accuracy of the one method is approximately equal to that of the other.

10. If this be so, a strong plea may be advanced in favour of the human test. Shortly expressed: human (tuberculised) subjects are readily available for observation. The procedure involves little preparation, and the results are easily read with exactness. The tuberculin under test is to be used thereafter in relation to the human subject. This fact enhances the value of the test observations.

If it be objected that in intracutaneous injection the amount of tuberculin introduced is measured more precisely, it may fairly be maintained that the droplet application of tuberculin is limited to a sharply defined area of skin surface and, further, that the clear skin of the human subject allows of more accurate estimation of the diameters of the areas of reaction.

The present enquiry has shown that assays on a variety of human (tuberculised) subjects yield consistent results, and similarly, assays on various animals give consistent results. Yet the animal results are not always contistent with the human results. The explanation of the discrepancy is not very clear. It is not impossible that certain strains of tuberculin act in less degree on the human subject and in greater degree on the animal, and conversely. The occurrence of such differences might be misleading and even involve risk, if standardisation tests were limited to animals without control from observations on the human subject.

If we grant, as the records have shown, that the procedure in relation to the human subject is sound and is innocuous to the human subject of the test, much may be said for the simplicity of the method and for the clarity of results obtained. As the tuberculins under test are destined for use on human subjects—for diagnostic and therapeutic purposes—it would seem reasonable, and probably safer, to base the standardisation of tuberculin (for human purposes) on observations in relation to man.

We report a case of fatal necrotizing pneumonia and sepsis caused by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in an otherwise well, 48-year-old Canadian man with type 2 diabetes mellitus who had travelled to Texas. Despite therapy that included intravenous antibiotics, intravenous immune globulin and other supportive measures, the patient succumbed to his illness. Recently, CA-MRSA pneumonia has been reported in several countries. The virulence of this organism may in part be related to its ability to produce toxins, such as Panton-Valentine leukocidin. As rates of CA-MRSA increase worldwide, physicians should be aware of the potential for MRSA to cause life-threatening infections in patients presenting to Canadian emergency departments (EDs). Necrotizing pneumonia caused by MRSA must be considered in the differential diagnosis of acute, severe respiratory illness. Early recognition of this syndrome in the ED may help physicians initiate appropriate antibiotic therapy in a timely manner.