Biomedical subjects
Publications and source records attributed to B Schwartz.
In a prospective study of untreated ocular hypertension 117 eyes were non-exfoliative and 20 eyes exfoliative. The percentage of optic disc pallor was significantly larger in the exfoliative than in the non-exfoliative group, whereas no significant differences were found in IOP or in the visual field.
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We examined 310 strains of Listeria monocytogenes by multilocus enzyme electrophoresis. Fifty-six electrophoretic types (ETs) of the organism were defined: 10 for serovar 4b strains, 11 for serovar 1/2b strains, and 30 for serovar 1/2a strains. Strains of serovars 1/2c, 3a, and 3b, and a non-typable strain were distributed among the remaining five ETs. The mean genetic diversity of the species was 0.41. Principal coordinate analysis revealed a sharp division among ETs which divided the species into two major clusters. ETs containing serovar 1/2a strains were in one cluster while all ETs containing serovar 4b, 1/2b, and 3b strains were in the second cluster. Except for two ETs that contained strains from both serovar 1/2b and serovar 3b, no ET contained strains from more than one serovar. Multilocus enzyme electrophoresis facilitated the analysis of epidemiologic data. In three separate epidemiologic investigations electrophoretic typing confirmed a common source as a cause of an outbreak; in a fourth investigation a single common source as a cause of an outbreak was effectively ruled out. Electrophoretic typing was also useful in documenting potential links between Listeria contaminated foods and persons with listeriosis who consumed those foods.
1. From 1981 to 1986, 6120 meadow voles (Microtus pennsylvanicus) were sampled for hematological indices in southeastern Manitoba, Canada. This survey revealed the sporadic occurrence of anemia in early winter at mean temperatures below about -5 degrees C. 2. Anemia was associated with leukocytosis and circulating normoblasts, suggesting a sudden, large blood loss. Individuals became anemic quickly, with no obvious predisposing factors. 3. Attempts were made to induce anemia by exposing voles in traps to various temperatures. Temperatures characteristic of most trapping sessions failed to induce anemia in both wild and laboratory-born voles. 4. Short-term exposure to more extreme temperatures (-20 to -30 degrees C) induced anemia. Voles lost blood through erosions of the epithelium of the glandular stomach, and developed other pathological lesions characteristic of hypothermia. 5. Although there was a strong association between cold weather and anemia, we could find no clear relationship between winter survival and winter weather. However, in 1984, extraordinarily cold temperatures were associated with anemia and a subsequent population decline. These events suggest a threshold mean daily temperature of about -15 degrees C, below which vole survival is grossly affected. 6. Deteriorating protein levels and energy reserves of small mammals in winter may make them particularly susceptible to cold stress. Hence, sporadic bouts of sustained cold may be responsible for some of the enigmatic winter declines seen in northern small mammals.
To measure retinal nerve fiber layer (NFL) thickness, three sets of simultaneous stereophotographs of the optic disc, taken with the Donaldson fundus camera, were measured at 5 degrees intervals in a stereoplotter (Kern PG2) at the surface of the internal limiting membrane (ILM) and the retinal pigment epithelium (RPE) along the disc margin. The NFL thickness was expressed as a ratio of the vertical disc radius. The reproducibility of the method showed that the percent coefficients of variation (CV%) for 15 normal, 10 ocular hypertensive, and 10 glaucomatous subjects were 5.2%, 6.0%, and 3.9%, respectively. The presence of a halo or scleral crescent had no significant effect on reproducibility. The photogrammetric technique for measuring NFL thickness appears to be highly reproducible and sensitive and may be a valuable quantitative method for: (1) early detection of optic nerve damage from glaucoma and other optic neuropathies and (2) monitoring progression of retinal NFL defects.
The authors conducted a case-control hospital-based study to assess the prevalence of systemic diseases and drugs in 161 cataract extraction patients and 196 surgical patients matched by age, sex, and race. The data were analyzed using matched multiple logistic regressions. A statistically significant increased risk of cataract extraction was found in patients with systemic hypertension (odds ratio [OR] = 1.49, 95% confidence interval [CI] = 1.06-2.09) and diabetes mellitus (OR = 1.79, 95% CI = 1.23-2.60). Estimation of the combined effect of systemic hypertension and diabetes mellitus resulted in an even higher risk for cataract extraction (OR = 2.66, 95% CI = 1.67-4.23). A positive association of cataract extraction and treatment of systemic hypertension with the diuretic furosemide was also found (OR = 1.95, 95% CI = 1.02-3.74).
A phosphorylation site was introduced into human interferon alpha A (IFN-alpha A) by site-specific mutation of the coding sequence. Three slightly different phosphorylation sites were created by using the predicted amino acid consensus sequences for phosphorylation by the cAMP-dependent protein kinase. The resultant modified interferons (IFN-alpha A-P) were expressed in Escherichia coli and purified. The purified proteins exhibit antiviral activity on bovine and human cells similar to that of the unmodified IFN-alpha A. The IFN-alpha A-P proteins can be phosphorylated by the catalytic subunit of cAMP-dependent protein kinase with [gamma-32P]ATP to high specific activity (2000-5000 Ci/mmol; 1 Ci = 37 GBq) with retention of biological activity. The 32P-labeled IFN-alpha A-P proteins bind to cells and can be covalently bound to the IFN-alpha/beta receptor with a bifunctional reagent as can human IFN-alpha A. The introduction of phosphorylation sites into proteins provides a procedure to prepare a large variety of radioactive proteins for research and clinical use.
From December 1986 to March 1987 an outbreak of Listeria monocytogenes infection occurred in the Philadelphia metropolitan area. A patient-control study showed patients were more likely than controls to have had an ill family member and to have used antidiarrheal medication during the month before their illness. Diet histories showed patients were significantly more likely to have eaten ice cream or salami than were controls, and to have shopped at one grocery store chain. Subtyping of L. monocytogenes isolates of patients showed no predominant strain, and cultures of food products eaten by patients were negative except for Brie cheese eaten by one patient. With no predominant strain of L. monocytogenes in the patients, a common source for this outbreak is unlikely. Thus, the identified risk factors may have been associated with carriage of L. monocytogenes and a coinfecting organism may have precipitated disseminated disease. Possible cofactors should be considered in investigations of future outbreaks of listeriosis.
Cesium-137 and 40K concentrations were measured in vegetation and in red-backed voles (Clethrionomys gapperi) in southeastern Manitoba, Canada, following the Chernobyl accident in 1986. Voles from wet coniferous habitats contained concentrations of 137Cs twenty- to fiftyfold higher than voles from deciduous habitats. Maximum 137Cs values were observed in autumn. Voles captured in a spruce bog at this time contained an average body burden of about 11 Bq. Concentrations in vegetation samples were similar to those found by other researchers. Overall, there was only minimal evidence of contamination attributable to Chernobyl in either vegetation or voles. The primary source of 137Cs in voles appeared to be dietary, particularly mushrooms that contained up to 74 Bq g-1 ash. Based on physiological constraints, mushrooms were the only plausible source of 137Cs in autumn diets. Elevated values at other times in coniferous areas may have been related to the consumption of epiphytic lichens. These findings suggest that fungi, or the animals that consume them, can serve as sensitive indicators of 137Cs contamination in the environment.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
In 1986-87 the Centers for Disease Control conducted an active population-based survey of Listeria monocytogenes infections in six regions of the United States. Listeriosis was reported in 154 patients: one-third of cases were perinatal and the remaining two-thirds occurred in the elderly and immunosuppressed. 28% of cases were fatal. 82 cases and 239 controls matched for age and underlying disease were enrolled in a study of risk factors for listeriosis. Cases were significantly more likely than controls to have eaten uncooked hot dogs or undercooked chicken, with 20% of the overall risk of listeriosis attributable to consumption of these foods. No other risk factors were identified.
During an outbreak of meningococcal meningitis in Saudi Arabia, oral rifampicin (four doses in two days) was compared with a single intramuscular dose of ceftriaxone for prophylaxis in family contacts of patients with meningococcal disease. Pharyngeal samples were taken for culture before and 1 and 2 weeks after administration. Both follow-up cultures indicated that ceftriaxone was significantly more effective. At 1 week the eradication rates for ceftriaxone and rifampicin were 97% and 75%; at 2 weeks they were 97% and 81%, respectively. No serious side-effects were associated with either agent. Ceftriaxone may provide an effective alternative to rifampicin for prophylaxis in meningococcal contacts.
The visual fields of 30 patients (subjects) with glaucoma were sent to six experienced clinicians (observers). Each subject had at least four visual field examinations on the OCTOPUS 201 automated perimeter spanning at least one year. Each observer was asked to review the visual field data of each subject and determine whether the visual fields were stable, improved, or worse over time. The visual field data were then analyzed using six different statistical models. In only 15 of the 30 subjects did at least five of the six human observers agree on the behavior of the visual field. Agreement among the statistical models was better, with at least five of the six models agreeing on 22 of the 30 subjects. It was concluded that there is, at present, no validated technique for detecting progressive visual field loss in glaucoma using automated perimetry when relatively few visual fields are available for analysis.
Photographs of the optic discs and fluorescein angiograms of 31 patients with open-angle glaucoma and 43 patients with ocular hypertension were evaluated for nerve fiber layer (NFL) defects and absolute fluorescein filling defects. All of the glaucomatous eyes showed both defects. Of the 43 ocular hypertensive eyes, in which both NFL and absolute fluorescein filling defects were evaluated, 9% had only NFL defects, 19% had only fluorescein filling defects, 14% had both defects, and 58% had neither defect. The percent area of fluorescein defect in the optic disc increased with severity of NFL defect in glaucoma and ocular hypertension. This study confirms the relationship of fluorescein filling defects and NFL defects to glaucomatous abnormalities and thus the association between vascular damage to the optic nerve and axon loss in glaucoma. The earliest objective evidence of glaucomatous damage can be detected with a combination of NFL evaluation and optic disc fluorescein angiography.
The aim of the present study was to investigate venom-related and venom-non-related immunological reactions in patients stung by bee or wasp. Sixteen consecutive patients (7 with local and 9 with systemic reactions) were tested with skin tests, RAST and basophil histamine release (BHR) test immediately after the insect sting and 2, 4, and 16 weeks later. No test was useful immediately after the insect sting, the "anergic period". In agreement with earlier findings, the SPT was the only allergy test that showed statistically significant differences between patients with local and systemic reactions, although a great overlap was found. Release of histamine from basophils after incubation with anti-IgE also showed statistically significant differences between local and systemic reactions. Further studies are needed, especially measurement of BHR after incubation with anti-IgE before insect stings.