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Biomedical subjects

M Ho

Publications and source records attributed to M Ho.

At least 271 records · Page 15Linked to original sources
PubMed1987

Effect of vegetarian diet on serum 1,25-dihydroxyvitamin D concentrations during lactation.

The effect of maternal diet on serum 1,25-dihydroxyvitamin D has not been determined in human lactation. Serum 1,25-dihydroxyvitamin D, other calcitropic hormones, osteocalcin, and minerals were examined in lactating and nonlactating women consuming a vegetarian or nonvegetarian diet. The vegetarian diet was a macrobiotic diet consisting primarily of whole cereal grains and vegetables; dairy products, eggs, and meats were generally avoided. We tested the thesis that the effect of lactation on serum 1,25-dihydroxyvitamin D is more pronounced in women on vegetarian diets than in those on nonvegetarian diets. Serum 1,25-dihydroxyvitamin D concentrations were significantly higher in lactating women compared with nonlactating women and in vegetarian compared with nonvegetarian women. Among vegetarian women, mean serum 1,25-dihydroxyvitamin D concentrations were 37% higher in the lactating group. For all subjects, serum parathyroid hormone was elevated during lactation compared with nonlactation. Thus, a vegetarian diet appears to be associated with increased serum 1,25-dihydroxyvitamin D during lactation.

Adult↗
PubMed1986

A critical reappraisal of the use of enzyme-linked immunosorbent assays in the study of snake bite.

The enzyme-linked immunosorbent assay (ELISA) has been the most widely used serological test in snake bite immunodiagnosis and epidemiology. The technique has been applied, however, without due consideration of the many factors which would affect an inherently sensitive test system, especially in tropical rural areas where large scale snake bite studies are usually carried out. This review discusses the effects of non-specific reactivity, cross reactivity and the quality of reagents on both the sensitivity and specificity of venom antigen and antibody detection assays. Simple laboratory modifications to optimize the assays are described. The importance of using the predictive value to assess the validity of applying the same test system in different circumstances is stressed. To fulfil its potential as the most versatile immunoassay technique in snake bite research, the test conditions of the ELISA will have to be much more stringently controlled in future.

Antibodies↗
PubMed1986

Antigen-specific immunosuppression in human malaria due to Plasmodium falciparum.

Proliferative responses of T lymphocytes to antigens specific and not specific for malaria were investigated in 32 adult patients in eastern Thailand during acute infection with Plasmodium falciparum malaria and during their convalescence. Immune unresponsiveness to malarial antigen, which persisted for more than four weeks in 37.5% of the individuals, was present in all patients, irrespective of parasitemia or severity of clinical illness. Suppression of responses to nonspecific antigens was less profound and observed only in patients with moderately severe or cerebral malaria. The depressed functional responses were associated with a loss of T lymphocytes--both helper and suppressor subsets--from the peripheral blood; these responses were recovered once parasites were cleared. These results indicate that blood-stage plasmodial infections may suppress responses important for immunity to malaria and so allow the parasite to survive. They further suggest that patients acutely or even recently infected with P. falciparum may not respond as well to a malaria vaccine as would uninfected individuals.

Adolescent↗
PubMed1986

Infections in heart-lung transplant recipients.

Infectious episodes were analyzed in 14 heart-lung transplant recipients who survived more than one week after transplantation. These patients had higher rates of infection than heart transplant recipients at our institution (P less than 0.01) and greater than 90% of all infections were potentially life-threatening. A total of 67% of all infections involved the lung or thoracic cavity as a primary site, and most of the rest were disseminated viral or fungal infections. Pneumocystis carinii infections occurred in six patients and were more common in this group than in patients who received heart transplants in the same period (P less than 0.005). Two patients followed more than one year developed a syndrome of chronic sputum production and bronchial colonization with Pseudomonas aeruginosa, which required recurrent treatment with i.v. antibiotics for symptomatic relief. The high rate of pulmonary infections in these patients presents a challenge to clinical management, and suggests that intensive and invasive monitoring for pulmonary infection is desirable.

Adult↗
PubMed1986

Randomized comparative trial of three monospecific antivenoms for bites by the Malayan pit viper (Calloselasma rhodostoma) in southern Thailand: clinical and laboratory correlations.

Three monospecific antivenoms for Malayan pit viper (MPV) (Calloselasma rhodostoma) were compared in Southern Thailand, where this species is the most common cause of snake bite morbidity. Forty-six patients with proved MPV bites and incoagulable blood, indicating systemic envenoming, were randomly allocated for treatment with Thai Red Cross (TRC), Thai Government Pharmaceutical Organization (GPO), or Twyford Pharmaceutical monospecific antivenoms. Both GPO and Twyford antivenoms produced rapid and permanent restoration of blood coagulability, but TRC antivenom failed in 2/15 cases. Patients in the GPO group showed the greatest increase in plasma fibrinogen concentration during the first 24 hr and had fewer early anaphylactic reactions (6/15) compared with Twyford 8/16 and with TRC 13/15. Pyrogenic reactions occurred more frequently after TRC antivenom (8/15) than GPO (1/15) or Twyford (0/16). Patients requiring more than one dose of antivenom were identifiably more severely envenomed on admission. In an accompanying laboratory study the antivenoms were assessed in rodents using five WHO standard tests of neutralizing activity. Compared with the other two antivenoms TRC was significantly inferior in anti-lethal potency, GPO was superior in anti-hemorrhagic and anti-necrotic potency and Twyford was superior in anti-procoagulant and anti-defibrinogenating potency. The clinical efficacy of these antivenoms against local necrosis remains equivocal. GPO and Twyford antivenoms are recommended for the treatment of systemic envenoming by MPV in an initial dose of 5 ampoules.

Adult↗
PubMed1986

Clinical significance of venom antigen levels in patients envenomed by the Malayan pit viper (Calloselasma rhodostoma).

Serial venom antigen levels were measured by enzyme-linked immunosorbent assay (ELISA) in 46 patients with systemic envenoming by the Malayan pit viper (Calloselasma rhodostoma), a major cause of snake bite in Southeast Asia. The principal effects of the venom are defibrination, hemorrhage and local tissue necrosis. Admission venom levels, which varied between 0 and 595 ng/ml, correlated with the incidence of spontaneous systemic bleeding, blood incoagulability and concentrations of plasma fibrinogen and serum fibrin degradation products. The presence or absence of nonclotting blood also correlated with the time elapsed between the bite and hospital admission. The development of nonclotting blood may be delayed by up to 72 hr after the bite even though circulating venom and raised FDP may be detected at presentation. This is probably explained by a temporary equilibrium between synthesis and consumption of fibrinogen. Venom antigenemia recurred in 12 patients (26%) suggesting continuous absorption of venom from the wound or saturation of extravascular binding sites. Admission venom levels also correlated with the extent of local swelling and the occurrence of tissue necrosis at the site of the bite. Venom was detected in 87% of wound aspirates and 88% of urine specimens taken on admission. Tourniquets, of the type used in rural Thailand, did not delay the absorption of venom into the circulation.

Adolescent↗
PubMed1986

Telangiectases [corrected] of the anterior chest in homosexual men.

Physical examination by a single clinician showed that 17 of 51 asymptomatic homosexual men and 19 of 26 men with persistent lymphadenopathy had linear telangiectasias in a broad, crescent distribution across the chest. The telangiectasias were commonly associated with erythema in the same distribution. Of the 36 men with telangiectasias, 25 were positive for serum antibody to the human immunodeficiency virus (HIV), whereas only 15 of 41 men without telangiectasias were seropositive (p = 0.001). Biopsy studies of supraclavicular skin from 6 of the men with HIV antibody and telangiectasias showed a characteristic pattern of dilated blood vessels with a perivascular small-cell infiltrate; no endothelial proliferation was noted. This histopathologic pattern was not consistently observed in HIV-seronegative men regardless of whether they had telangiectasias. These data show that telangiectasias of the upper chest are a relatively common finding in homosexual men and that they are significantly, although not exclusively, associated with HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Visceral leishmaniasis unresponsive to antimonial drugs. I. Clinical and immunological studies.

Ten Kenyan patients with visceral leishmaniasis, unresponsive to sodium stibogluconate at a dose of 16 to 20 mg Sb/kg/day given for 30 to 98 days, have been studied clinically and immunologically and compared with 57 antimony-responsive patients. Pulmonary tuberculosis and previous treatment with antimonial drugs were the only factors which were more common in unresponsive patients. The degree of immunosuppression and rate of recovery of immunoreactivity did not differ between antimony-responsive and -unresponsive patients. Only one patient had never been treated before (primary unresponsiveness). In the other nine patients secondary unresponsiveness occurred after one or more treatment courses, suggesting that the parasite developed resistance to antimony. Antimony-unresponsiveness in visceral leishmaniasis is a serious problem numerically, clinically and economically. A plea is made that the initial treatment of visceral leishmaniasis should be adequate in dose and duration.

Antimony Sodium Gluconate↗
PubMed1985

Visceral leishmaniasis unresponsive to antimonial drugs. II. Response to high dosage sodium stibogluconate or prolonged treatment with pentamidine.

Ten Kenyan patients with visceral leishmaniasis unresponsive to sodium stibogluconate, at a dose of 16 to 20 mg Sb/kg body-weight/day given for 30 to 98 days, were treated with 20 mg Sb/kg bw given every eight hours. This regimen was modified or abandoned in six patients because of suspected toxicity, although toxicity was difficult to assess because of intercurrent illness. Toxic effects included lethargy, anorexia, vomiting, electrocardiographic changes, fall in haemoglobin and rise in liver enzymes. One patient died, probably from a cardiac arrhythmia. Two patients were cured, four responded partially and four showed no response. Pentamidine, at a dose of 4 mg/kg body-weight given one to 3 times per week for 5 to 39 weeks, was given as initial treatment in one patient and after failure of sodium stibogluconate in seven. Toxic effects included nephritis, hepatitis, transient diabetes and subcutaneous abscesses. Two patients were cured, two responded partially, three showed no response and one, after apparent cure, relapsed and was unresponsive to additional pentamidine treatment. Low-frequency, long-duration pentamidine was often useful in maintaining any improvement made during treatment with the less well tolerated high-dose, high frequency sodium stibogluconate. We observed the step-wise development of resistance to both sodium stibogluconate and pentamidine. The problems of managing patients with visceral leishmaniasis which is unresponsive to conventional doses of pentavalent antimonials are discussed and some tentative suggestions put forward.

Amidines↗
PubMed1985

Epstein-Barr virus infections and DNA hybridization studies in posttransplantation lymphoma and lymphoproliferative lesions: the role of primary infection.

Fourteen patients who developed B cell lymphomas or lymphoproliferative lesions after kidney, liver, heart, or heart-lung transplantation in Pittsburgh during 1981-1983 had active infection with Epstein-Barr virus (EBV) of the primary (six patients), reactivated (seven patients), or chronic (one patient) type. In transplant patients without tumors, the incidence of EBV infection was 30% (39 of 128). Only three of these patients had primary infections. Thus the frequency of active infection was significantly higher in patients with tumors, and patients with primary infections were at greater risk of developing tumors. Five of 13 tumors tested contained EBV nuclear antigen (EBNA) and nine of 11 contained EBV genomes detected by DNA-DNA hybridization with BamHI K, BamHI W, or EcoRI B cloned probes. All EBNA-positive tumors, except one, were also positive by hybridization. Only one tumor was negative for both EBNA and EBV DNA. These data suggest that EBV plays an etiologic role in the development of these lesions.

Adolescent↗
PubMed1985

Morbidity of cytomegalovirus infection in recipients of heart or heart-lung transplants who received cyclosporine.

Forty-four heart and five heart-lung transplant recipients with cytomegalovirus (CMV) infection were investigated for risk factors associated with symptomatic CMV infection (17 patients) and CMV pneumonia (eight patients). Symptomatic infection was associated with primary rather than reactivated infection (P less than .005), younger age (P less than .005), heart-lung transplantation (P less than .001), and significant rises in titer of antibody to the early antigen of Epstein-Barr virus (P less than .001). Among recipients of heart transplants, patients with cardiomyopathy more often had symptomatic disease due to CMV (P less than .05). CMV pneumonia was associated with heart-lung transplantation and, in patients with primary CMV infection, earlier positive cultures for CMV after transplantation (P less than .02). CMV viremia was found in all patients with symptomatic infection, including the eight patients with CMV pneumonia, and the frequency of positive buffy coat cultures for CMV was significantly higher in patients with symptoms than in patients without symptoms (P less than .001). Neither symptomatic CMV infection nor CMV pneumonia was significantly associated with the use of antithymocyte globulin, restricted to therapy for rejection, and the use of high doses of acyclovir in 11 patients had no demonstrable impact on CMV culture positivity.

Acyclovir↗
PubMed1985

Acute respiratory failure due to Pneumocystis carinii pneumonia: clinical, radiographic, and pathologic course.

The clinical, radiographic, and pathologic correlates of acute respiratory failure due to Pneumocystis carinii pneumonia were studied in 12 renal transplant patients treated with cyclosporin (CS) and prednisone. Six patients required only supplemental oxygen, while the other six patients developed the adult respiratory distress syndrome (ARDS) requiring prolonged mechanical ventilation despite similar predisposing factors and prompt initiation of therapy. Ten (83%) patients survived. Increased frequency of human leukocyte antigen (HLA) DR6 was noted in six of the 11 patients tested. The resolution of radiographic infiltrates was significantly slower in ARDS patients; however, there was no apparent difference in the severity of early alveolar damage between the two groups. There was also no association between the development of ARDS due to P. carinii pneumonia and the mean daily dose of CS and prednisone, the presence of cytomegalovirus infection or pneumonia, HLA-DR6 antigen, or initial hypoxemia.

Acute Disease↗
PubMed1985

Fungal infections in liver transplant recipients.

Sixty-two adults who underwent orthotopic liver transplantations between February 1981 and June 1983 were followed for a mean of 170 days after the operation. Twenty-six patients developed 30 episodes of significant fungal infection. Candida species and Torulopsis glabrata were responsible for 22 episodes and Aspergillus species for 6. Most fungal infections occurred in the first month after transplantation. In the first 8 weeks after transplantation, death occurred in 69% (18/26) of patients with fungal infection but in only 8% (3/36) of patients without fungal infection (P less than 0.0005). The cause of death, however, was usually multifactorial, and not solely due to the fungal infection. Fungal infections were associated with the following clinical factors: administration of preoperative steroids (P less than 0.05) and antibiotics (P less than 0.05), longer transplant operative time (P less than 0.02), longer posttransplant operative time (P less than 0.01), duration of antibiotic use after transplant surgery (P less than 0.001), and the number of steroid boluses administered to control rejection in the first 2 posttransplant months (P less than 0.01). Patients with primary biliary cirrhosis had fewer fungal infections than patients with other underlying liver diseases (P less than 0.05). A total of 41% (9/22) of Candida infections resolved, but all Aspergillus infections ended in death.

Adult↗
PubMed1985

Isolation and characterization of novel suppressor T cell clones from murine fetal thymus.

Murine fetal thymus from C57BL/6J (B6) and DBA/2J contains a cell population that suppresses CTL responses to alloantigens. This suppressor cell population was found to exist in high frequency in murine fetal thymus at the 14th day of gestation. The activity of this cell in the thymus declined rapidly with increasing time of gestation, and suppressor activity in the thymus was undetectable by the time of birth. On the other hand, suppressor activity could be detected in organ cultures of 14-day fetal thymus even after the organs were cultured for 14 or 21 days. Fetal thymocytes from B6 or DBA/2J mice were grown as long-term lines in interleukin 2 (IL 2)-containing medium. Clones of suppressor cells were derived from long-term cultures by micromanipulation. The clones had an average doubling time of 13 to 16 hr and were dependent on IL 2 for growth. The clones were 10- to 100-fold more efficient in suppressing CTL responses to alloantigens than day 15 fetal thymocytes. Analyses of cell surface molecules with the use of monoclonal antibodies and conventional anti-H-2 sera by radioactive binding assays showed that cloned suppressor cells from B6 fetal thymus were Thy-1 and Lyt-2+, and expressed little or no L3T4, Lyt-1, H-2K, H-2D, and class II molecules. The suppressor clones lacked the cytolytic activity of conventional CTL and also served as very poor target cells in CTL-mediated cytolysis. The suppressor function of the cloned cells was radiation-resistant, and this suppression could not be reversed by the addition of excess exogenous IL 2. The cloned cells suppressed CTL responses only when they were added within the first 48 hr of a 5-day culture period. Analyses of the antigen specificity of the suppressor cells showed that they suppressed CTL responses in a nonantigen-specific manner.

Animals↗
PubMed1985

Ontogeny of proliferative and cytotoxic responses to interleukin 2 and concanavalin A in murine fetal thymus.

The ontogeny of proliferative and cytotoxic responses to concanavalin A (Con A) and interleukin 2 (IL 2) in C57BL/6J (B6) fetal thymus (FT) was investigated. Embryonic thymocytes were either taken from embryos at different times of gestation or from 14 day B6 FT that were maintained as organ cultures for various times. It was found that the B6 FT could proliferate to Con A and EL4 SN (an IL 2 containing culture supernatant) in a synergistic fashion. This synergy between Con A and EL4 SN was first observed at the 16th to 17th day of gestation. A similar differentiation process took place in 14-day FT that had been maintained as organ cultures; the synergy between Con A and EL4 SN was first observed after 3 days in organ culture. This synergy increased with increasing time of organ culture, and was most evident after 10 days. The synergy between Con A and EL4 SN was also observed when the EL4 SN was replaced with IL 2 which had been purified from crude EL4 SN to apparent homogeneity. B6 FT could also form cytotoxic T lymphocytes (CTL) on stimulation with Con A and EL4 SN. Con A-activated CTL (polyspecific) were detected by including phytohemagglutinin in the assay medium. CTL response was first detected in the 17-day fetal thymus by using this assay. In organ cultures, CTL responses were first detected after 4 days in organ culture, and reached peak levels after 12 to 14 days. The CTL precursor (CTL-P) frequencies in the B6 FT after 2, 5, 10, and 14 days in organ culture were less than 1/10,000, 1/2232, 1/297, and 1/70, respectively; the corresponding CTL-P frequency in adult thymus was 1/60. After 6 days in organ culture, B6 FT could also form CTL in response to Con A and pure IL 2. This finding suggests that the ability to synthesize other differentiation factors that are required for CTL responses is acquired at an early time of thymic differentiation.

Animals↗
PubMed1984

Reversibility of lymphomas and lymphoproliferative lesions developing under cyclosporin-steroid therapy.

Post-transplant lymphomas or other lymphoproliferative lesions, which were usually associated with Epstein-Barr virus infections, developed in 8, 4, 3, and 2 recipients, respectively, of cadaveric kidney, liver, heart, and heart-lung homografts. Reduction or discontinuance of immunosuppression caused regression of the lesions, often without subsequent rejection of the grafts. Chemotherapy and irradiation were not valuable. The findings may influence policies about treating other kinds of post-transplantation neoplasms.

Adolescent↗
PubMed1984

The development of pseudohypoparathyroidism. Involvement of progressively increasing serum parathyroid hormone concentrations, increased 1,25-dihydroxyvitamin D concentrations, and 'migratory' subcutaneous calcifications.

The hormonal changes in the development of pseudohypoparathyroidism ( PSH ) have not, to our knowledge, been previously reported. The male sibling of a child with PSH was studied for 2 1/2 years. At 1 year of age he had generalized subcutaneous calcifications that subsequently migrated over his body. At 3 years of age and over a six-month period, serum calcium levels fell; serum phosphorus, parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D (1,25-[OH]2D) concentrations increased. There was no calcemic, phosphaturic, or urinary cyclic adenosine monophosphate response to PTH. The concentration of serum PTH was suppressed by infusion of calcium and doubled with edetic acid infusion, indicating that the parathyroids were sensitive to changes in calcium levels. Thus, increasing PTH and increased 1,25-(OH)2D concentrations occur in the development of PSH . Migratory skin calcifications may occur. We speculate that increasing the serum PTH level reflects increasing compensatory parathyroid production to overcome a progressive PTH receptor defect and serves, with increased 1,25-(OH)2D concentrations, to prevent severe falls in serum calcium concentrations in the early stage of the disease.

Calcinosis↗