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Biomedical subjects

L R Ash

Publications and source records attributed to L R Ash.

At least 19 recordsLinked to original sources
PubMed2000

Permanence of Fungi-Fluor epifluorescence stain to detect microsporidia.

OBJECTIVE: Epifluorescence microscopy, a methodology for the screening of bodily fluids and tissue specimens for microsporidia species, was directed to evaluate the retention of epifluorescence of fixed and stained specimens over time. METHODS: Thirty samples of stool, bodily fluids, duodenal touch preparations, and biopsies, were tested for the retention of their epifluoresence using the Fungi-Fluor procedure. Specimens were examined under a 330- to 380-nm UV filter at the time of preparation, 3 wk later, and then at monthly intervals for 18 months. All specimens were reevaluated for the presence or absence of fluorescence and any decrement of fluorescence over time. No special preservation techniques were used on any of the slides. RESULTS: All 30 specimens maintained their epifluorescence from the time of slide preparation to 18 month later. No decrement in fluorescence was noted in any sample examined. Accuracy and ease of spore identification was maintained. CONCLUSIONS: Epifluorescence microscopy demonstrates the utility of this technique for archival study of microsporidia-containing specimens over prolonged periods of time.

Animals↗
PubMed1998

Balantidiasis in Aymara children from the northern Bolivian Altiplano.

Balantidium coli infection was coprologically studied in 2,124 Aymara children 5-19 years of age from the schools of 22 communities of the northern Bolivian Altiplano over a five-year period. Infection with B. coli was found in 11 of the communities surveyed, with prevalences of 1.0-5.3% (overall prevalence=1.2%). The prevalences observed are some of the highest reported and did not differ significantly among the various age groups or between boys and girls. These prevalences, the apparent absence of symptoms or signs of illness due to this parasite in the schoolchildren surveyed at the time of stool sampling, and the consistency of stool samples of the infected students suggest that they are apparently asymptomatic carriers. Infection with B. coli must be considered as an endemic anthropozoonosis in the area studied. A relationship between B. coli infection and Altiplanic pigs is suggested.

Adolescent↗
PubMed1997

Microscopic diagnosis of blood parasites following a cytoconcentration technique.

An isotonic fixative (formalin and thimerosal) solution, with a saponin additive to lyse erythrocytes and platelets, has been developed. The formalin and thimerosal ensure good preservation of blood parasites. This fixative has led to the development of a new concentration technique using cytocentrifugation (cytospin) in the search for Plasmodium spp., Leishmania spp., and microfilariae, as well as leukocytes in which parasites or pigment may be present. The concentration of the parasites present in the sediment from 100 microl of blood spread on a 6-mm diameter circle results in good morphology that is well stained using the usual Giemsa or Wright techniques. This new technique has the advantage of a relatively low cost and offers the possibility of isolating and identifying in the same sediment the main blood-stage parasites, with the exception of young trophozoites, of Plasmodium falciparum.

AIDS-Related Opportunistic Infections↗
PubMed1995

Eosinophilic colitis associated with larvae of the pinworm Enterobius vermicularis.

Various helmintic parasites, most of which are uncommon in economically developed countries, can cause abdominal pain and eosinophilic inflammation of the bowel. A homosexual man presented with severe abdominal pain and haemorrhagic colitis, eosinophilic inflammation of the ileum and colon, and numerous unidentifiable larval nematodes in diarrhoeal stool. His symptoms resolved with anthelmintic treatment alone. Using comparative morphology and molecular cloning of nematode ribosomal RNA genes, we identified the parasites as larvae of the pinworm Enterobius vermicularis, which are rarely observed or associated with disease. Occult enterobiasis is widely prevalent and may be a cause of unexplained eosinophilic enterocolitis.

Adolescent↗
PubMed1995

Susceptibility of various mosquitoes of California to subperiodic Brugia malayi.

Laboratory experiments were conducted to determine the susceptibility of six species of mosquitoes, representing three genera, to subperiodic Brugia malayi. The black-eye, Liverpool strain of Aedes aegypti was the susceptible control. Mosquitoes were fed on microfilaremic jirds (Meriones unguiculatus). All mosquitoes, except wild caught Culex erythrothorax, were laboratory-reared and allowed to feed when 8 to 10 days old. Anopheles freeborni, Anopheles hermsi, and Culiseta inornata proved refractory. Both Anopheles species allowed invasion of flight muscle and development to the late first stage, after which larval growth ceased and melanization occurred. Culiseta inornata prevented any larval development. Culex tarsalis and Cx. erythrothorax proved highly susceptible to B. malayi infection. In all, 95.6% and 88.7% of the Cx. tarsalis harbored third-stage larvae after infective feedings of 15.7 and 81.8 mf/microliters of blood, respectively, while only 11.5% were found susceptible when microfilaremia was low (1.1 mf/microliters). Culex erythrothorax demonstrated a susceptibility rate of 82.3% with 17.0 mf/microliters. Both Culex species appear to be excellent experimental hosts for subperiodic B. malayi. This is the first conclusive evidence that mosquitoes of the genus Culex can naturally support the complete development of a stain of subperiodic B. malayi.

Animals↗
PubMed1995

Epidemiology of isosporiasis among persons with acquired immunodeficiency syndrome in Los Angeles County.

To determine factors associated with isosporiasis in persons with acquired immunodeficiency syndrome (AIDS) in Los Angeles County, data from the AIDS surveillance registry were analyzed for the eight-year period 1985-1992. Isosporiasis was reported in 127 (1.0%) of 16,351 persons with AIDS during the study period. Prevalence of infection was highest among foreign-born patients (3.2%), especially those from El Salvador (7.4%) and Mexico (5.4%), and in all persons of Hispanic ethnicity (2.9%). Persons with a history of Pneumocystis carinii pneumonia (PCP) were less likely than PCP-negative patients to have isosporiasis (0.2% and 1.4%, respectively, P < 0.01). A decrease in the prevalence of isosporiasis in patients negative for PCP was observed beginning in 1989 (P = 0.02). Prevalence decreased with age (P < 0.01, by chi-square test for trend). After controlling for multiple factors by logistic regression, isosporiasis was more likely to occur in foreign-born patients than in those born in the United States (adjusted odds ratio [OR] = 5.8, 95% confidence interval [CI] 3.4, 9.9, P < 0.001) and in Hispanics than in whites (non-Hispanics) (adjusted OR = 3.5, 95% CI 1.7, 7.2, P < 0.001). A prior history of PCP continued to be negatively associated with isosporiasis (adjusted OR = 0.2, 95% CI 0.1, 0.3, P < 0.001). Age and time remained independently associated with infection. These data suggest that isosporiasis among persons with AIDS in Los Angeles County may be related to travel exposure and/or recent immigration and that the use of trimethoprim-sulfamethoxazole (TMP-SMX) for PCP may effectively prevent primary infection or expression of latent isosporiasis. Physicians should have an increased index of suspicion for Isospora in AIDS patients with diarrhea who have immigrated from or traveled to Latin America, among Hispanics born in the United States, in young adults, and in those not receiving PCP prophylaxis. Food and water precautions should be advised and TMP-SMX prophylaxis considered for the prevention of Isospora infection for patients with human immunodeficiency virus infection who travel to Latin America and other developing countries.

AIDS-Related Opportunistic Infections↗
PubMed1994

Municipal drinking water and cryptosporidiosis among persons with AIDS in Los Angeles County.

To assess unfiltered drinking water as a source of cryptosporidium infection in patients with the acquired immunodeficiency syndrome (AIDS) the prevalence of cryptosporidiosis among persons with AIDS in Los Angeles County was assessed by water service area. One water distributor, serving approximately 60% of the county's residents (area B), has consistently employed filtration. The other company, which serves the remainder of the county (area A), did not institute filtration until mid-December 1986. This difference provided a 'natural experiment' in which to assess the effect of municipal water filtration on the level of cryptosporidiosis among persons with AIDS. The prevalence of cryptosporidiosis among AIDS patients was compared for the two water service areas for the time period (1983-6) preceding the implementation of filtration in area A. From 1983 to 1986 the age-standardized prevalence of cryptosporidiosis among AIDS patients was 32% lower in area A (4.2%), which received unfiltered water, than in area B (6.2%). Following addition of filtration in area A, the prevalence of cryptosporidiosis among AIDS patients decreased by 20%; however, a decline, of 47%, was also observed in area B. The similar baseline levels of cryptosporidiosis and the corresponding post-filtration decline in both areas suggest that filtration had no effect on levels of cryptosporidiosis among persons with AIDS. Thus it does not appear that municipal drinking water is an important risk factor for cryptosporidiosis in AIDS patients residing in Los Angeles County.

AIDS-Related Opportunistic Infections↗
PubMed1994

Epidemiology of cryptosporidiosis among persons with acquired immunodeficiency syndrome in Los Angeles County.

To determine the occurrence and factors associated with Cryptosporidium among persons with acquired immunodeficiency syndrome (AIDS) in Los Angeles County, data were analyzed from the AIDS surveillance registry for the 10-year period 1983-1992. Among 16,953 persons with AIDS, a total of 638 (3.8%) cryptosporidiosis cases were reported during the study period. The prevalence of cryptosporidiosis was higher in persons whose suspected human immunodeficiency virus (HIV) exposure category was through sexual contact (3.9%) than among persons in other HIV exposure categories (2.6%; P < 0.01) and in immigrants from Mexico (5.2%) than in American born patients (3.8%; P < 0.01). Blacks (2.7%) were less likely than whites (4.1%) and Latinos (4.2%) to be reported with cryptosporidiosis (P < 0.001). A temporal trend was observed from 1983 to 1986 when the prevalence decreased from 6.7% to 3.6% (P < 0.001, by chi-square test for trend). After controlling for confounding variables by stratified analysis, persons whose HIV exposure was sexual (adjusted odds ratio [OR] = 1.7, 95% confidence interval [CI] 1.3, 2.4, P < 0.01) and immigrants from Mexico (adjusted OR = 1.6, 95% CI 1.2, 2.1, P < 0.01) were more likely to have cryptosporidiosis. The negative association with black race remained significant (adjusted OR = 0.7, 95% CI 0.57, 0.96, P = 0.02). The prevalence of cryptosporidiosis decreased with age in gay and bisexual males (Mantel-Haenszel test for trend, P < 0.01) but not among female and heterosexual male cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1994

Plasma retinol-binding protein levels of children under five years of age in a displaced Sudanese community.

Blood samples (100-160 microliters) were obtained from 1360 children by a finger prick in heparinized collection tubes, and an LC-Partigen retinol-binding protein (RBP) kit was used for quantification of RBP in the plasma. Only three boys and two girls had plasma RBP that was equal to or more than 3.0 mg/dL, a recommended cut-off point for normal values. The mean +/- SD) plasma RBP levels were at 1.150 +/- 0.613 mg/dL for boys (N = 689) and 1.233 +/- 0.572 mg/dL for girls (N = 671). The difference between boys and girls was statistically significant (p < 0.001). None of the children included in this study had eye signs of vitamin A deficiency. Two hundred eighty-two children (19.6%) received vitamin A supplements (200,000 IU) before the beginning of the study. The mean +/- SD for plasma RBP for children who received vitamin A supplement were 1.159 +/- .762 mg/dL for boys and 1.151 +/- 0.470 mg/dL for girls. The observed discrepancy between the biochemical and clinical manifestations of vitamin A deficiency was discussed.

Age Factors↗
PubMed1992

Interrelationship between diarrhea and vitamin A deficiency: is vitamin A deficiency a risk factor for diarrhea?

A cross-sectional study, a follow-up study and an evaluation of impact of community-based distribution of vitamin A capsules (200,000 IU) were conducted in Omdurman (Sudan) between November, 1988, and March, 1989. In the cross-sectional survey 1441 children less than 5 years of age participated, which established the baseline values for plasma retinol-binding protein. During the follow-up period 290 cases of diarrhea occurred. Low concentrations of plasma retinol-binding protein (less than 1.85 mg/dl) proved to be a risk factor for diarrhea, especially in girls. The relative risk increased after the second year of life. Children who received vitamin A supplementation before commencement of the study had a lower incidence of diarrhea. The protective effect of vitamin A supplementation was greater in girls (relative risk, 0.297; 95% confidence interval, 0.240 to 0.368) than in boys (relative risk, 0.404; 95% confidence interval, 0.352 to 0.464).

Child, Preschool↗
PubMed1991

Onchocerciasis in a California dog.

A 15-year-old dog that had lived all of its life on ranches and at the Wildlife Waystation on the western edge of the San Gabriel mountains near Los Angeles, California, developed an extensive granulomatous lesion involving the right eye and associated tissues requiring removal of both the eye and the lesion. Microscopic examinations of the tissues revealed the presence of living and dead gravid female worms and male worms belonging to the genus Onchocerca. Unsheathed microfilariae presumed to be Onchocerca species were found in the skin as well. Because Onchocerca species are not natural parasites of dogs, it is presumed that this infection was acquired accidentally from bovine, equine, or other animal host sharing the environment. This appears to be the first published record of patent onchocerciasis in a dog.

Animals↗