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Biomedical subjects

L R Ash

Publications and source records attributed to L R Ash.

At least 55 records · Page 3Linked to original sources
PubMed1978

Further observations on spontaneous neoplasms in the Mongolian gerbil, Meriones unguiculatus.

One hundred sixty Mongolian gerbils, Meriones unguiculatus, were examined for the presence of naturally occurring lesions. The first recognized cases of cecal adenocarcinoma, testicular teratoma, and sebaceous gland pad carcinoma were found. Neoplasms previously reported from the gerbil and also seen in the present study included ovarian theca lutein and granulosa lutein cell tumors, sebaceous gland pad adenoma, cutaneous squamous cell carcinoma, malignant melanoma, and renal and splenic hemangiomas. Calcinosis cutis was also observed in two male gerbils.

Adenocarcinoma, Mucinous↗
PubMed1978

Ultrastructure of the anterior alimentary tract of infective-stage Wuchereria bancrofti (Nematoda: Filarioidea).

The anterior alimentary tract of infective-stage Wuchereria bancrofti is divided into the following segments: stoma or buccal capsule, muscular esophagus, glandular esophagus, esophageal-intestinal valve, and intestine. Invaginated external cuticle lines only the anterior stoma. External cuticle and esophageal lining are not continuous and are ultrastructurally distinct; the latter is compared morphologically to the amorphous component of elastin. The glandular esophagus is a composite structure of a stellate contractile epithelial core, surrounded by a sleeve of secretory epithelium. The glandular cytoplasm shows evidence of formation and release of dense secretory granules. At least 2 nerve cell bodies lie within the esophagus approximately 15 micrometer anterior to the esophageal-intestinal valve and their associated processes pass forward and backward through the contractile epithelium. Materials interpreted as ingested flight muscle mitochondria of the mosquito vector appear in various stages of degeneration within the intestinal lumen. It is suggested that, although simple by comparison to some other nematodes, the anterior alimentary tract of infective-stage W. bancrofti functions in the ingestion and breakdown of nutrient materials. The ultrastructure of the excretory cell likewise suggests a functional capability.

Aedes↗
PubMed1978

Increased susceptibility to infection with Brugia pahangi in aged female jirds (Meriones unguiculatus).

Female Mongolian jirds, Meriones unguiculatus, from 5 age groups of 2, 12, 16, 21, and 28 months, were infected with Brugia pahangi. Infections were followed for 125 days by weekly bleedings beginning 55 days postinoculation. Jirds were then killed and adult parasites recovered. Results showed a significant shortening of the prepatent period in the 12-, 21-, and 28-month-old groups. The proportion of gravid female worms did not vary significantly among the 5 groups. Similarly, the ratio of females to male worms showed little variation from group to group. Microfilaremia data for the 5 infection groups show an age-associated increase in numbers of circulating microfilariae. Some individuals in the 28-month group demonstrated 1,500 to 3,000 microfilariae per 0.25 ml peripheral blood, a level that was not approached by young females.

Aging↗
PubMed1977

Sensitivity and specificity of skin reactivity to Brugia malayi and Dirofilaria immitis antigens in Bancroftian and Malayan filariasis in the Philippines.

Saline antigen extracts of microfilariae, adult worms and third-stage larvae of subperiodic Brugia malayi maintained in gerbils were prepared for use as skin test reagents. Patients were studied on three different islands in the Philippines, one endemic for Bancroftian filariasis (Sorsogon, Luzon), another endemic for Malayan filariasis (Palawan) and the third without endemic filariasis (Cebu). A dose-response curve was established initially in patients with Bancroftian filariasis: thereafter 1.0 microng of the B. malayi antigens and 0.05 microng of Dirofilaria immitis FST antigen (obtained from Dr. T. Sawada) were used. Sizes of reactions were measured by recording the diameters of wheals at 20 minutes, 24 and 48 hours. There was a very high correlation in immediate hypersensitivity reactions among the three B. malayi antigens. Reaction sizes followed a normal distribution. When an area of an antigen-induced wheal 3 X that of the saline control was considered a positive reaction, 99% of 150 patients with Bancroftian filariasis and 96% of 45 subjects with Malayan filariasis reacted to B. malayi larval antigen. Only 68% of patients with Bancroftian filariasis but 90% of those with Malayan filariasis reacted to D. immitis FST antigen. There was no relationship between skin reactivity and age, sex, microfilaremia or severity of clinical disease. Approximately half of 50 patients who lived in an endemic area for W. bancrofti but had neither patent infection nor clinical disease reacted to B. malayi antigens. A maximum of 7% of 120 age- and sex-matched controls from Cebu gave false positive reactions with any of the antigens. Only a small proportion of patients gave 24- and 48-hour reactions. It is concluded that the use of antigens prepared from a human parasite, subperiodic B. malayi, which is easily maintained in a laboratory animal host, improves the ability to diagnose filarial infections by immunological means.

Adult↗
PubMed1977

Weak mixed lymphocyte culture response in the Mongolian gerbil (Meriones unguiculatus).

A study was made to determine whether the mixed lymphocyte culture test could detect histocompatibility differences between two strains of the Mongolian gerbil, Meriones unguiculatus. A semi-micro mixed lymphocyte culture was developed using 6 X 10(5) stimulating and responding cells per 0.12 ml culture volume at a ratio of 1:1. A culture period of 120 hours was found to be optimal. Although a weak allogeneic response was demonstrated with the Uclp:(MON) strain responding to stimulating cells from the MON/Tum strain, the reverse was not seen. A mixed lymphocyte reaction to xenogeneic (mouse) cells was demonstrated, and response to the mitogen, phytohemagglutinin, was strong. These data and the low stimulation index obtained in allogeneic culture supported the view that histocompatibility differences among different strains of the Mongolian gerbil are weak.

Animals↗
PubMed1975

The ultrastructure of adult Brugia malayi (Brug, 1927) (Nematoda: Filarioidea).

The ultrastruct of the adult subperiodic Brugia malayi (Brug, 1927) within pulmonary arteries of male jirds (Meriones unguiculatus) was studied by transmission electron microscopy. The cuticle consists of 10 sublayers (2 of which are prominently banded) and a typical outer unit membrane. Evidence is presented showing that the subcuticular region of the lateral chords comprises a functional complex of basal infoldings, multivesicular bodies, and associated mitochondria, which is probably engaged in the exchange of solutes across a permeable cuticle. Microbodies with paired, prominent cores, intracisternal A-particle viruslike bodies, nonstaining glycogen patches, and other structures are also present in the lateral chords. The platymyarian somatic musculature shares some coelomyarian characteristics, e.g., apparent neuromuscular connections and prominent glycogen deposits surrounded by mitochondria and other organelles. The alimentary tract has features typical of many nematodes. The luminal segments of the male and female reproductive tracts and their germinal products, excluding microfilariae, are described. Affinities with related species are discussed.

Animals↗
PubMed1975

Repeated infections of Brugia pahangi in the jird, Meriones unguiculatus.

Male jirds, Meriones unguiculatus, were subcutaneously inoculated in the groin with 1 to 5 doses of infective-stage larvae of Brugia pahangi at weekly or monthly intervals. When a dose of either 25 or 75 larvae or 4 weekly doses of 25 larvae were given, 15-16% of the larvae were recovered as adults approximately 4 to 7 months post inoculation. Only 8-10% of the larvae were recovered if 4 weekly or 5 monthly doses of 75 larvae each were given. After an inoculation of 75 larvae, 25% of the worms were recovered at 30 days. The 30 day-old population consisted of an average of 10 female and 8.8 male worms. Jirds previously inoculated with 4 weekly or 5 monthly doses were challenged with an additional 75 larvae 30 days prior to necropsy. An average of only 4.5 thirty day-old female worms were recovered in these cases, presenting a 55% decrease as compared to the single inoculation situation. There was some decrease in the mean length of female worms in multiply-inoculated jirds, but no difference in the mean lengths of the male worm population from singly or multiply-inoculated jirds was observed. No differences in prepatent periods or in patterns of microfilaraemia were observed in singly or multiply-inoculated jirds.

Animals↗
PubMed1975

Spontaneous lesions and parasites of the Mongolian gerbil, Meriones unguiculatus.

Four-hundred-eighty Mongolian gerbils, Meriones unguiculatus [Uclp:(MON)], most of which were experimentally infected with filarial worms, were examined for spontaneous lesions. Previously unrecognized lesions included cutaneous squamous cell carcinoma, duodenal adenocarcinoma, malignant blue nevus, hepatic choleangiocarcinoma, malignant hemangiopericytoma of the uterus, ovarian teratoma, chronic interstitial nephritis, renal cortical retention cysts, splenic hemangiomas, and various histologic abnormalities of the lung. Previously reported lesions also seen in the present study were a malignant melanoma, adrenal cortical adenoma or carcinoma, uterine leiomyoma, sebaceous gland adenoma, hepatic lymphangioma, and renal hemangioma. Hymenolepis diminuta (Cestoda) and Tyrophagus castellani (Acarina) were accidentally recovered from experimental animals. Tritichomonas caviae and a species of Entamoeba were the most common intestinal protozoa. Tyzzer's disease, however, was clearly the most significant infectious disease of gerbils in the UCLA School of Public Health colony.

Adenoma↗