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Biomedical subjects

M Ho

Publications and source records attributed to M Ho.

At least 307 records · Page 17Linked to original sources
PubMed1983

An enzyme-linked immunosorbent assay (ELISA) for field diagnosis of visceral leishmaniasis.

A simplified enzyme-linked immunosorbent assay (ELISA) was evaluated as a diagnostic test for visceral leishmaniasis in the field on 222 individuals with splenomegaly and 110 controls. The test was shown to have a sensitivity of 98.4% and specificity of 100% when compared with parasite identification by splenic aspiration. The data indicate that the ELISA is an accurate, safe, and economical alternative to splenic aspiration for the diagnosis of visceral leishmaniasis.

Enzyme-Linked Immunosorbent Assay↗
PubMed1983

Resistance and susceptibility of mice to bacterial infection. IV. Functional specificity in natural resistance to facultative intracellular bacteria.

The effect of opsonic antibody on resistance of susceptibility of three strains of mice, C57Bl/10, BALB/c, and CBA to the intracellular bacteria Listeria monocytogenes, Salmonella typhimurium, and Brucella abortus was tested. Bacteria were opsonized by serum treatment before their injection into mice, or the mice were preimmunized by injection with alcohol killed bacteria which induces antibody without macrophage activation. Antibody did not increase the rate of clearance of Listeria from the bloodstream, nor did it affect the subsequent growth of that organism in the spleen and liver. Blood clearance of S. typhimurium and of B. abortus was increased by preopsonization with specific antibody, indicating that opsonins were a limiting factor in resistance to these two bacteria. However, neither opsonization before infection nor immunization with alcohol killed vaccines had any effect on the strain distribution of resistance/susceptibility, which differs for each of the three intracellular pathogens. Thus, even in the presence of adequate opsonization the three strains of mice showed different patterns of resistance/susceptibility to Listeria, S. typhimurium, and B. abortus. This implies that each has a unique cellular mechanism of early nonspecific resistance.

Animals↗
PubMed1983

Immunosuppression in Kenyan visceral leishmaniasis.

Cell-mediated immune responses were evaluated in 15 patients with active visceral leishmaniasis from Masinga location in eastern Kenya where the disease is endemic. Age and sex matched controls were selected from a village school in the same area. In vivo studies were carried out by skin testing with leishmanin, tuberculin, streptococcal and candida antigens. Lymphocyte blastogenic transformation to the mitogens phytohaemagglutinin (PHA) and concanavalin A (Con A) and the antigens purified protein derivative (PPD), streptokinase-streptodornase (SKSD) and leishmanial antigen (LA) was studied in vitro. The results showed that immunosuppression in visceral leishmaniasis in Kenya was both specific and non-specific. In the majority of patients there was complete anergy to all antigens in vivo and in vitro. The suppression of responses to mitogens was less marked. Recovery of non-specific responses preceded the development of specific immunity. In a small number of patients (23%) immune unresponsiveness to leishmanial antigens persisted 1 year after parasitological cure.

Adolescent↗
PubMed1982

Prevalence and disease spectrum in a new focus of visceral leishmaniasis in Kenya.

A cross-sectional community study was conducted in the village of Kivaa in Machakos District, Kenya, to determine the prevalence and disease spectrum of visceral leishmaniasis. The disease was first diagnosed in 1978. Demographic data was collected from 50 households comprising 374 individuals. Clinical examination, laboratory investigations and leishmanin skin tests were performed. The results showed that in spite of the presence of a susceptible population, visceral leishmaniasis occurred with a low prevalence in Kivaa as evidenced by the small number of individuals with active disease (0.30%), a low leishmanin positivity rate (7.2%) and the presence of leishmanial antibodies in only 3.7% of the population. The infection affected individuals in homesteads with or without nearby termite hills. Leishmanial antibodies and leishmanin positivity were found among asymptomatic household contacts of patients as well as in isolated individuals in non-infected homesteads. These findings suggest the existence of a spectrum of disease ranging from asymptomatic to self-healing to severe clinical illness. Furthermore, there was significant clustering of leishmanin reactors in the households of patients. The aetiology of this striking focality of visceral leishmaniasis remains obscure. Possible explanations are discussed.

Adolescent↗
PubMed1982

Serum calcitonin response to administration of calcium in newborn infants during exchange blood transfusion.

In 25 newborn infants, 30 "exchange" transfusions were performed. Pre-exchange serum calcitonin concentrations of newborn infants were higher than those of normal adults and of donor blood used for exchange transfusion. A gradual decline of serum calcitonin concentrations was observed with increasing postnatal age. Serum calcium and magnesium concentrations were inversely related to serum calcitonin concentrations. Newborn infants had significant elevations of serum calcitonin values within a few minutes after the administration of calcium. Gestationally younger infants (less than or equal to 33 weeks) had significantly more pronounced and swifter elevations of serum calcitonin concentrations after calcium administration than gestationally more mature infants (less than 33 weeks). We speculate that calcitonin may be an important "fetal hormone" and that increased calcitonin concentrations may relate to the pathogenesis of neonatal hypocalcemia.

Calcitonin↗
PubMed1982

Effect of prolonged administration of interferon-alpha on pharmacokinetics, fever, lymphocyte proliferative response, and NK cell activity.

Over a 60-week period, a patient with multiple warts received a total of 281 x 10(6) units of human leukocyte interferon (IFN-alpha) by intramuscular (IM) or intralesional (IL) injections. Circulating IFN was significantly higher following IM administration than after IL administration. These pharmacokinetics did not change. The patient's body temperature was always significantly elevated after administration of IFN. However, hyporeactivity to the febrile response developed when the interval between repeated injections of IFN was less than six days. The lymphocyte count was significantly decreased within 5-7 h after administration of IFN and had returned to normal by 24 hours, whereas total WBC, platelet, and monocyte counts were not altered. There was a depression of specific lymphocyte proliferative response to herpes simplex virus after multiple daily injections, but not after prolonged therapy. Circulating natural killer (NK) levels were not elevated during the first two months of IFN therapy. After the patient had received about 100 x 10(6) units of IFN, however, the NK cell level became elevated and remained elevated upon cessation of treatment. NK activity was stimulated by in vitro incubation of peripheral mononuclear cells with 1000 units of IFN during the initial phase of treatment. A decline of in vitro stimulation of NK activity by interferon developed during two subsequent periods of treatment with mean daily doses of 2.46 and 1.07 x 10(6) units of IFN. Long-term therapy in our patient with an average of 4.7 x 10(6) units of IFN/week was well tolerated, did not irreversibly affect platelet or white cell counts or nonspecific or virus-specific cell mediated immune responses, and enhanced circulating NK levels.

Adult↗
PubMed1982

Effects of interferon-alpha on human warts.

Two patients with extensive warts which were stable for two years or more were treated with human interferon-alpha to assess the ability of interferon to affect this benign tumor of viral etiology. Intramuscular administration of 96.6 and 135 million units over 12-15 weeks produced softening and decreased scaling of each patient's warts. Double blind, placebo-controlled intralesional injections resulted in progressive disappearance of interferon treated warts. A dose response relationship was shown in eight warts. The minimum effective dose was 1.2 x 10(6) units injected over 15.5 weeks.

Adult↗
PubMed1982

Resistance and susceptibility of mice to bacterial infection. IV. Genetic and cellular basis of resistance to chronic infection with Brucella abortus.

The number of Brucella abortus strain 19 organisms in the spleens of CBA/H mice peaked two weeks after intravenous injection of 5 X 10(6) organisms. With the onset of specific cell-mediated immunity, 90% of the bacteria were killed, but approximately 10(6) bacteria persisted up to seven weeks after infection. In contrast, in BALB/c, C57BL/10, and B10Br mice, bacterial numbers peaked at two weeks but decreased steadily with the onset of bactericidal activity. In all strains, clearance of bacteria from the liver was relatively efficient. The course of infection in (CBA/H X BALB/c) F1 mice was similar to that in CBA/H mice, indicating that the mechanism(s) leading to slower recovery from infection was dominant. The H-2 haplotype of the mice did not influence the rate of recovery from infection. The use of backcross mice showed that multiple genes were involved. In bone marrow-chimeric mice, resistance was determined by the genome of the bone marrow donor, not that of the host.

Animals↗
PubMed1982

Effect of cyclosporin A on murine natural killer cells.

In mice, cyclosporin A decreased the natural killer cell-enhancing effect of two interferon inducers, infective murine cytomegalovirus and nonreplicating Newcastle disease virus. It also inhibited murine cytomegalovirus replication at doses greater than 20 mg/kg, but it did not significantly inhibit interferon induction by Newcastle disease virus. In cell culture, cyclosporin A had no direct effect on the natural killer activity of spleen mononuclear cells derived from normal or murine cytomegalovirus-infected animals. However, at 50 micrograms/ml it significantly reduced the ability of interferon to enhance the natural killer activity of normal spleen cell suspensions. The inhibitory effect of cyclosporin A on natural killer cell activity in infected mice may be partly explained by its ability to block the action of interferon.

Animals↗
PubMed1982

Modulation of natural killer cell activity in mice after interferon induction: depression of activity and depression of in vitro enhancement by interferon.

Splenic natural killer (NK) cell activity of BALB/c and C3H mice was assayed after administration of the interferon inducers Escherichia coli endotoxin or Newcastle disease virus (NDV). As expected, the NK cell activity rose early in response to the interferon inducers. At 1 to 3 days after an injection of endotoxin, NK activity was hyperesponsive to interferon stimulation. At 5 to 9 days after injection of either endotoxin or NDV, splenic NK activity was depressed, and the spleen cells showed a relative refractoriness to in vitro interferon stimulation. It is postulated that this phenomenon may be related to hyporeactivity, the inability to reinduce interferon after an initial period of interferon production.

Animals↗
PubMed1981

Herpes simplex infection in acute myelogenous leukemia and other hematologic malignancies: a prospective study.

To better define the frequency and clinical characteristics of herpes simplex virus (HSV) infection in adult patients with acute myelogenous leukemia (AML), the authors prospectively studied 29 patients undergoing remission induction chemotherapy with twice weekly throat wash cultures for an average of 25.3 days. Ten seropositive patients (34.5%) shed HSV at least once. Eight patients were asymptomatic. Two episodes of herpes labialis were severe and persistent, but no visceral dissemination was observed. Reactivation of HSV infections in AML patients presumably with marked immunosuppression occurs, but less frequently and more benignly than has been suggested. Daunomycin and cytosine arabinoside, which can inhibit HSV replication, may have accounted for this lower frequency of reactivation.

Adolescent↗
PubMed1981

Elevated serum 1,25 dihydroxyvitamin D concentrations in rickets of very low-birth-weight infants.

Elevated 1,25 dihydroxyvitamin D concentrations were found in five VLBW infants who developed rickets at two to three months postnatal age or term postconceptual age; 25 hydroxyvitamin D concentrations were low. Bone mineralization was found to be extremely low as measured by infant-adapted direct photon absorptiometry. After treatment with a formula supplemented with additional Ca and P, there was a rapid improvement in bone mineralization with a concomitant decrease of 1,25(OH)2D to normal adult values, whereas 250HD values increased and parathyroid hormone values decreased. In the VLBW infants studied, we suggest that rickets may be caused by Ca and P deficiency rather than by a deficiency of vitamin D metabolism.

Calcitriol↗