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Biomedical subjects

D Waters

Publications and source records attributed to D Waters.

At least 163 records · Page 9Linked to original sources
PubMed1988

Risk of human immunodeficiency virus (HIV-1) infection among laboratory workers.

In a prospective cohort study of 265 laboratory and affiliated workers, one individual with no recognized risk factors for human immunodeficiency virus type 1 (HIV-1) infection was HIV-1 seropositive at the time of entry into the study. Molecular analyses of two HIV-1 isolates derived in two independent laboratories from a blood sample from this worker showed that the isolates were indistinguishable from a genotypic form of HIV-1 present in the H9/HTLV-IIIB cell line. Exposure to this strain of virus most probably occurred during work with concentrated virus or culture fluids from virus-producing cell lines under standard Biosafety Level 3 containment. Although no specific incident leading to this infection has been identified, undetected skin contact with virus culture supernatant might have occurred. This worker was the only one found to be positive among the subgroup of 99 workers who shared a work environment involving exposure to concentrated virus. The incidence rate of 0.48 per 100 person-years exposure indicates that prolonged laboratory exposure to concentrated virus is associated with some risk of HIV-1 infection, which is comparable to the risk for health care workers experiencing a needle stick exposure. While none of the ten workers with parenteral exposure to HIV-1 in this cohort became infected, a worker in another laboratory did seroconvert following an injury with a potentially contaminated needle. Strict Biosafety Level 3 containment and practices should be followed when working with concentrated HIV-1 preparations, and further refinement of the procedures may be necessary.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Design features of a controlled clinical trial to assess the effect of a calcium entry blocker upon the progression of coronary artery disease.

This report presents the design and methodological features of a double-blind, randomized, placebo-controlled, trial in 383 patients with coronary artery disease. The study's principal objective is to determine whether chronic treatment with a calcium entry blocker can retard the progression of coronary artery disease. The study population consists of patients with coronary artery disease and a baseline coronary arteriogram that qualifies them as being at high risk for disease progression. After satisfying all entry criteria, patients were randomized to receive either the calcium entry blocker nicardipine or placebo. All indicated concomitant medications except calcium entry blockers are permitted. Patients are being followed clinically for 24 months before undergoing a second coronary arteriogram. The effect of the treatments on a variety of clinical and angiographic parameters will be determined.

Adult↗
PubMed1987

Successful management of acute retinal necrosis with intravenous acyclovir.

Two patients (3 eyes) had a history and clinical findings typical of acute retinal necrosis syndrome. Ten-day treatment with intravenous acyclovir and topical cycloplegia resulted in rapid resolution of the vitreoretinal findings and a swift return to near normal vision. All three eyes have maintained normal vision, and there have been no retinal detachments over a year after treatment.

Acyclovir↗
PubMed1981

Isolation of Clostridium difficile from the environment and contacts of patients with antibiotic-associated colitis.

Clostridium difficile is the most important cause of antibiotic-associated colitis, but its epidemiology remains unknown. Using a selective medium for the isolation of C. difficile, cultures were obtained from the environment and contacts of hospitalized patients carrying C. difficile in their stools. In areas where carriers had diarrhea, 85 (9.3%) of 910 cultures of floors and other surfaces, especially those subject to fecal contamination, were positive. In areas where there were no known carriers, only 13 (2.6%) of 497 cultures of similar sites were positive (P less than 0.005). C difficile was isolated from hands and stools of asymptomatic hospital personnel, from sewage and soil, and from the home of a patient. Environmental isolates were toxigenic. C. difficile inoculated onto a floor persisted there for five months. Further studies are needed to document how often floor persisted there for five months. Further studies are needed to document how often C. difficile shed by patients with antibiotic-associated colitis is acquired by other persons and whether isolation precautions are capable of limiting the organism's spread.

Anti-Bacterial Agents↗
PubMed1979

Fer de Lance virus (FDLV): a probable paramyxovirus isolated from a reptile.

A new virus has been isolated by inoculation of lung tissues of diseased snakes into snake embryos. Homogenates of infected embryo tissues caused c.p.e. in cell cultures incubated at 30 degrees C. The virus replicates in a wide variety of reptilian or mammalian cell types incubated at 30 degrees C, inducing either syncytium formation or minimal or no cytopathic changes. Efficient replication occurs in embryonated hens' eggs at 27 to 30 degrees C. The virus haemagglutinates guinea pig and chick erythrocytes; it possesses a neuraminidase similar to the receptor-destroying enzyme of Vibrio cholera. Electron microscopic observations of infected cells examined in thin section revealed pleomorphic viruses 146 to 321 nm in diam. resembling known myxoviruses. Internal nucleocapsid strands are 15 to 16 nm in diam.; nucleocapsid observed in negatively stained preparations measures 14 nm in diam. The virus was determined to possess a nucleoprotein core containing a 50S single-stranded unsegmented RNA genome. All characters of the virus are similar to those of the paramyxovirus group except that the nucleocapsid diam. is intermediate between that of paramyxoviruses and pneumoviruses. The virus is antigenically distinct from known myxoviruses and is unique among myxoviruses in its restriction to growth at temperature below 37 degrees C.

Animals↗
PubMed1978

Cell-mediated immunity to measles, myelin basic protein, and central nervous system extract in multiple sclerosis. A longitudinal study employing direct buffy coat migration inhibition assays.

Cell-mediated immunity to myelin basic protein, to an extract of central nervous system white matter, and to measles virus nuclear core, was studied nine patients with multiple sclerosis in a serial longitudinal fashion using in vitro inhibition of buffy coat migration. The mean migration index to all antigens at various times before, during, and after exacerbation of multiple scelrosis in the patients did not differ from the index in a reference group of normal subjects. The incidence of inhibition of migration induced by central nervous system white matter and basic protein was greater than in serially studied normal subjects (p less than 0.05, p less than 0.2 less than 0.1, respectively) but bore no definite relation to clinical course.

Antigens↗
PubMed1976

In vitro cellular responsiveness in multiple sclerosis patients to a purified measles virus nuclear core and to other viral antigens.

The Clausen modification of the peripheral blood buffy coat leukocyte migration test was used to test patients with multiple sclerosis, normal subjects and patients with other neurologic diseases for cell-mediated immunity to commercial measles virus, purified nuclear core material from a human neurotropic strain of measles virus, as well as to commercial preparations of rubella, mumps and parainfluenza HA2. Leukocytes of multiple sclerosis patients showed significantly less mean inhibition of migration in the presence of both measles antigens, mumps and parainfluenza but no difference from controls when incubated with rubella. No correlation could be found between the degree of migration inhibition and concomitant serum anti-measles neutralization antibody titers to the same strain of virus. The use of purified viral antigens might result in more meaningful studies of the status of cellmediated immunity to viral antigens in multiple sclerosis. The relationship of our findings to other studies in this area and to the pathogenesis of multiple sclerosis is discussed.

Antibodies, Viral↗
PubMed1975

In vitro cellular responsiveness in multiple sclerosis patients to a viral isolate from multiple sclerosis brain tissue and to other antigens.

The Clausen modification of the leukocyte migration test was used to test patients with multiple sclerosis, normal subjects, and patients with other neurologic diseases for cell-mediated immunity to 6/94 virus (a parainfluenza virus previously isolated from the brain tissue of a multiple sclerosis patient), c-RNA virus isolated from a tumor, and the nonviral antigens Candida and purified protein derivative. Leukocytes of multiple sclerosis patient showed significantly less mean inhibition of migration by the 6/94 virus (but not by the c-RNA virus, purified protein derivative, and Candida) than did the cells of normal controls and patients with other neurologic diseases. The relationship of these findings to previous observations in this area and to the pathogenesis of multiple sclerosis is discussed.

Antigens, Viral↗
PubMedDate not supplied

Impact of delayed reperfusion of myocardial hibernation on myocardial ultrastructure and function and their recoveries after reperfusion in a pig model of myocardial hibernation.

UNLABELLED: This study examined the effect of delayed reperfusion of myocardial hibernation from 24 hours to 7 days on myocardial ultrastructural and functional changes and their recoveries after reperfusion. BACKGROUND: We have previously shown in pigs that after reperfusion the functional and structural alterations in short-term myocardial hibernation which was reperfused in 24 hours can recover in 7 days. The effect of delayed reperfusion of hibernating myocardium on the extent and severity of cellular and extracellular structural changes of hibernating myocardium, and their recoveries after reperfusion is not known. METHODS AND RESULTS: A severe LAD stenosis was created in 27 pigs, reducing resting flow by 30-40% immediately after placement of the stenosis and producing acute ischemia as evidenced by regional lactate production, a decrease in regional coronary venous pH, reduced regional wall thickening (from 38.5 +/- 5.1% to 10.4 +/- 8.0%) and a 33% reduction of regional oxygen consumption. The stenosis was maintained either for 24 hours in 9 pigs (group 1) with LAD flow of 0.65 +/- 0.13 ml/min/g (38% reduction), or for 7 days in 17 pigs (group 2) with LAD flow of 0.67 +/- 0.14 ml/min/g (36% reduction). There were no differences (p = NS) in the reduction of wall thickening, rate-pressure product, lactate production, or regional oxygen consumption between group 1 and group 2. Quantitative morphometric evaluation of the ultrastructure on electromicrographs revealed a greater decrease in sarcomere volume and a higher incidence of myocytes with reduced sarcomere volume in 7-day than in 24-hour hibernating regions (53 +/- 19% versus 33 +/- 14%, p < 0.05). Patchy myocardial necrosis with replacement fibrosis was common, but 6 of the 18 pigs had no myocardial necrosis or replacement fibrosis in the 7-day hibernating group, and 4 of 9 pigs had no patchy myocyte necrosis in the 24 hour hibernating group. In 6 pigs in group 1 in which the stenosis was then released and hibernating myocardium reperfused in 24 hours, regional wall thickening recovered to 30 +/- 6% (p = NS compared to baseline) after one week of reperfusion. In 12 pigs in group 2 in which the stenosis was released and hibernating myocardium reperfused in 7 days, regional wall thickening recovered slowly, from 10.1 +/- 7.2% to 18.1 +/- 8.3% at one week (n = 5) and to 28.0 +/- 3.6% at 3-4 weeks of reperfusion (n = 7, p < 0.05 compared to baseline). Similarly, the sarcomere volume or myofilament recovered significantly (p < 0.01) and was not different compared to the normal region (p = NS) in the 24-hour hibernating region of group 1, but the recovery was much slower and was incomplete at 4 weeks (p < 0.01) compared to baseline in the 7-day hibernating region of group 2. Recovery of regional wall thickening correlated with ultrstructural recovery (p < 0.01). By multivariate stepwise regression analysis, the degree of LAD flow reduction, the extent of fibrosis, and myofilament loss were independent predictors of the extent of functional recovery. CONCLUSIONS: In a porcine model of myocardial hibernation with myocardial hypoperfusion, systolic dysfunction, and metabolic adaptations, a longer period of myocardial hibernation with delayed reperfusion was associated with more severe abnormalities of myocytes. an increasing interstitial fibrosis, and more protracted myofibrillar and functional recoveries after reperfusion. The extent of functional recovery is related to the degree of coronary flow reduction, the severity of the ultrastructural changes, and the extent of interstitial fibrosis.

Animals↗