Biomedical subjects

M Wharton

Publications and source records attributed to M Wharton.

54 records · Page 3Linked to original sources

PubMed1990

A large outbreak of antibiotic-resistant shigellosis at a mass gathering.

In July 1987, a large outbreak of shigellosis occurred among attendees at a mass gathering in a national forest, the annual Rainbow Family Gathering. Sanitation in the campsite was poor, allowing widespread transmission of disease, probably by food, water, and person-to-person spread. The attack rate may have been greater than 50% among the estimated 12,700 attendees. The outbreak was caused by Shigella sonnei, resistant to ampicillin, tetracycline, and trimethoprim-sulfamethoxazole; the organism was of colicin type 9 and contained a 90-kilobase plasmid not found in non-outbreak-related strains. The dispersal of the group resulted in nationwide dissemination of the organism, and outbreaks in three states were linked to transmission from attendees at the Gathering. This outbreak demonstrates the potential for rapid dissemination of disease in such a setting and the necessity for careful planning of mass gatherings.

Age Factors↗

PubMed1990

Mumps transmission in hospitals.

Although sporadic transmission of mumps within hospitals to patients and staff is well documented, outbreaks of mumps within hospitals have only rarely been reported. The widespread mumps outbreaks that occurred in Tennessee in 1986-1987 provided an opportunity to assess the extent of the problems caused by mumps in hospitals. Information was obtained from 146 (95%) of 154 infection control practitioners in the state. Infection control problems caused by mumps were reported from 17 (12%) of 146 hospitals. The 17 hospitals in which these incidents occurred were located in counties that accounted for 67% of the reported mumps cases statewide during this period. Although most cases of mumps in health care workers were community-acquired, six health care workers in three different hospitals developed mumps following nosocomial exposure. In two institutions, nine patients contracted mumps while hospitalized. Both were long-term-care facilities housing adolescents, who had substantial contact with a community where mumps outbreaks were ongoing. This study suggests that mumps poses a small but real risk to both patients and staff in hospitals, particularly in long-term-care facilities caring for adolescents and young adults. In communities where mumps activity is ongoing, hospitals should consider identifying potentially susceptible staff members at risk for infection and offering vaccine. Likewise, susceptible patients in long-term-care facilities should be immunized.

Cross Infection↗

PubMed1990

Measles, mumps, and rubella vaccines.

With widespread use of the live virus vaccines for measles, mumps, and rubella, there has been a dramatic decrease in the incidence of all three diseases. At the same time, an increasing proportion of the remaining cases are occurring in adolescents and adults. Thus, vaccinations for these three diseases of childhood must be included in a comprehensive program for adult immunization. The vaccines have a proven history of safety and efficacy and are usually administered together as combined measles-mumps-rubella (MMR) vaccine. Vaccination for measles, mumps, and rubella is particularly important for susceptible adults likely to come in contact with infected children. Adults at particularly high risk for exposure may include daycare center workers, teachers and other school employees, college students, medical personnel, and those planning to travel outside the United States.

Age Factors↗

PubMed1989

Fatal carbon monoxide poisoning at a motel.

One man died and four other persons required hospitalization following accidental exposure to carbon monoxide at a motel. In spite of prompt diagnosis of the index cases, a search for the source of exposure and for other possible victims was delayed more than ten hours. Subsequent investigation revealed that air conditioning units drew carbon monoxide from the gas heaters for the motel's indoor swimming pools into three adjacent guest rooms through structural defects in the walls. Emergency care providers must remember that in environmental exposures, other persons may continue to be at risk, and efforts must be made to identify them.

Adult↗

PubMed1988

Mitochondrial iron loss from leukemia cells injured by macrophages. A possible mechanism for electron transport chain defects.

Activated macrophages inhibit replication of murine lymphoblastic leukemia L1210 cells without lysis. This inhibition of replication is associated with abnormalities of mitochondrial electron transport at the level of NADH dehydrogenase (NADH-DH) and succinate dehydrogenase (SDH). The mechanism of inhibition is unknown, although it has been demonstrated that as NADH-DH and SDH activity is lost, iron is released from cells. Because both NADH-DH and SDH contain numerous iron-sulfur clusters, damage to these structures may be one result of injury by activated macrophages. L1210 cells were labeled with 55Fe and co-cultivated with activated murine peritoneal macrophages (injured L1210 cells). At 48 h, injured L1210 cells had released 83 +/- 8% (mean +/- SEM of 55Fe activity into the media, compared with 25 +/- 4% release from control and 37 +/- 7% from nondividing mitomycin C-treated control cells. All cells were greater than 90% viable. These differences were also reflected in the iron content of the cells. Mitochondria were then separated by centrifugation after cell disruption and 55Fe activity was found to be similarly decreased in both mitochondrial and nonmitochondrial fractions of injured L1210 cells. To further characterize the changes in mitochondrial iron content, mitochondrial proteins from injured and control L1210 cells were separated by IEF and 55Fe activity of gel slices was determined. There was selective loss of 55Fe activity in the area of the gel corresponding to SDH and NADH-DH, suggesting that iron loss from iron-sulfur clusters may occur in L1210 cells injured by activated macrophages. Iron uptake into L1210 cells after removal from macrophages showed a rapid large influx of radioactive iron. L1210 cells in contact with macrophages appear to develop an iron-depleted state, which is dependent on the continued presence of macrophages.

Animals↗

PubMed1988

A large outbreak of mumps in the postvaccine era.

During a county-wide mumps outbreak in Nashville, Tennessee, 332 cases of mumps were identified at a public high school (attack rate, 18.8%). A pep rally 17 d before the peak of the outbreak at a single public high school may have provided an opportunity for point-source exposure. A case-control study demonstrated that vaccine efficacy was 75% (we used provider-verified records and excluded students with a history of mumps disease). Although school records were nonuniform, mumps immunization status was correct, compared with provider-verified records, in at least 85% of both cases and controls. Parental reports were much less reliable. The cost of the outbreak was estimated at $154/case. Receiving mumps vaccine at a vaccine clinic held after the outbreak had peaked was associated with a decrease in risk of mumps disease. Thus, these clinics may have a role in the control of such outbreaks.

Adolescent↗

PubMed1987

Small animals are not susceptible to human immunodeficiency virus infection.

Several species of small animals were inoculated at birth or as adults with blood components from patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related disorders, or with the human immunodeficiency virus (HIV). No ill effects were noted in rats, hamsters, guinea-pigs, rabbits or musk shrews. Mice inoculated with clinical specimens had a significant incidence of mortality as compared with control groups (18.7% against 5.9%, P less than 0.025). Mice receiving HIV showed an increase in mortality, but it was not statistically significant. Infection of the animals by HIV could not be detected by virological or immunological studies. We concluded that none of these animal species provided a useful model for evaluating HIV infection.

AIDS-Related Complex↗

PubMed1986

Circulating immune complexes in patients with acquired immune deficiency syndrome contain the AIDS-associated retrovirus.

Using the polyethylene glycol (PEG) precipitation technique, circulating immune complexes were demonstrated in 88% of patients with acquired immune deficiency syndrome (AIDS) and AIDS-related disorders. The finding of immune complexes in these individuals was confirmed by using a second assay, the commercially available Clq-IgG enzyme-linked immunosorbent assay kit. The material precipitated by PEG contained elevated levels of IgG, IgM, Clq, and C3. There was no substantial correlation between the level of IgG in the complexes and the serum IgG concentration, although there was a significant association between complexed IgG and the titer of anti-AIDS-associated retrovirus (ARV) antibody in the serum. In some precipitates, ARV antigens were detected by immunoblot analysis. Coculture of other precipitates with normal lymphocytes revealed the presence of infectious virus. These data confirm the existence of immune complexes in the sera of AIDS patients and indicate that in some cases they may comprise ARV and anti-ARV antibodies.

Acquired Immunodeficiency Syndrome↗

PubMed1986

Experimental anaerobic liver abscess: observations on treatment.

Various treatment modalities for solitary anaerobic liver abscesses were evaluated in a recently-described rabbit model. In the first phase of the experiment, 35 rabbits with liver abscesses induced with Bacteroides fragilis and Fusobacterium necrophorum were randomized into four groups: surgical drainage alone, drainage plus clindamycin 150 mg IM 8-hourly, clindamycin alone, and untreated controls. Serum clindamycin concentrations in rabbits were similar to those achieved in humans. The survival of rabbits receiving antibiotic chemotherapy alone was significantly better than controls, whereas the survival of those having surgical drainage with or without chemotherapy was not. However, successful surgical drainage was followed by weight gain in surviving rabbits. In the second phase of the experiment 18 rabbits with abscesses were randomized into the same groups. Aspirates of pus from all rabbits receiving clindamycin were sterile by day 7 of treatment, but high bacterial counts were still present in the abscess cavities of control rabbits and of those undergoing drainage alone. These findings illustrate the application of a new model for pyogenic liver abscess in laboratory investigation. Their relevance to management of human pyogenic liver abscesses remains to be assessed.

Animals↗

PubMed1986