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Biomedical subjects

M L Huang

Publications and source records attributed to M L Huang.

At least 55 records · Page 3Linked to original sources
PubMed1994

Human herpesvirus 6 and pneumonia.

Studies of lung tissues and bronchoalveolar lavage specimens from patients with pneumonia have led some investigators to propose that human herpesvirus 6 (HHV-6) can cause pneumonia. As the etiologic role of HHV-6 in pneumonia remains poorly defined, cases of pneumonia that are associated with pulmonary HHV-6 infection are best described as HHV-6-associated pneumonias. The clinical spectrum of HHV-6-associated pneumonia encompasses both mild and severe cases. Most cases reported so far occurred in immunosuppressed individuals following bone marrow transplantation or HIV infection. Some studies have identified coinfections with HHV-6 and other viruses in a surprising number of HHV-6-associated pneumonias. Although no systematic evaluation of treatment regimens is available at this time, coincidental administration of antiviral drugs did not generally result in clinical improvement. Controlled, prospective studies are needed to understand the clinical presentation, clinical course, etiology, diagnosis and treatment of HHV-6-associated pneumonias.

Adult↗
PubMed1994

The pharmacokinetics of risperidone in humans: a summary.

Risperidone is rapidly and completely absorbed after oral administration; less than 1% is excreted unchanged in the feces. The principal metabolite was found to be 9-hydroxyrisperidone. Hydroxylation of risperidone is subject to the same genetic polymorphism as debrisoquine and dextromethorphan. In poor metabolizers the half-life of risperidone was about 19 hours compared with about 3 hours in extensive metabolizers. However, becuase the pharmacology of 9-hydroxyrisperidone is very similar to that of risperidone, the half-life for the "active fraction" (risperidone +9-hydroxyrisperidone) was found to be approximately 20 hours in extensive and poor metabolizers. We found that risperidone exhibited linear elimination kinetics and that steady state was reached within 1 day for risperidone and within 5 days for the active fraction.

Aged↗
PubMed1993

Human herpesvirus 6 in lung tissue from patients with pneumonitis after bone marrow transplantation.

BACKGROUND: Human herpesvirus 6 (HHV-6) is a recently described herpesvirus that is epidemiologically and biologically similar to cytomegalovirus. It is the cause of exanthem subitum (roseola) in children. METHODS: To evaluate the possible role of HHV-6 infection in pneumonitis in immunocompromised patients, we used quantitative HHV-6 polymerase chain reactions to study lung-biopsy specimens from 15 patients with pneumonitis after bone marrow transplantation and lung tissue from 15 immunocompetent subjects without pneumonitis and 6 fetuses. RESULTS: HHV-6 DNA was detected in lung tissue from all 15 patients, from 14 seropositive control subjects, and from none of the 7 seronegative control subjects. Six patients had levels of HHV-6 DNA in lung tissue that were 10 to 500 times higher than those in any of the other patients or control subjects. Increased levels of HHV-6 DNA correlated with a decreased risk of death from pneumonitis (P = 0.015), an increased severity of graft-versus-host disease (P = 0.023), and the presence of idiopathic pneumonitis (P = 0.037). Levels of HHV-6 DNA correlated directly with the changes in HHV-6 antibody titers in the interval between the pretransplantation period and the open-lung biopsy (P = 0.002). Low levels of HHV-6 antibody at the time of the open-lung biopsy were also associated with the diagnosis of idiopathic pneumonitis (P = 0.002). CONCLUSIONS: The concentrations of HHV-6 genome in lung tissue and their relation to changes in serologic titers support an association between HHV-6 infection and idiopathic pneumonitis in immunocompromised hosts.

Adolescent↗
PubMed1993

Pharmacokinetics of orally administered levocabastine in patients with renal insufficiency.

The effects of renal insufficiency and hemodialysis on the pharmacokinetics of orally administered levocabastine were studied in six nondialysis patients and in six patients undergoing regular hemodialysis. Levocabastine .5 mg, supplied as a solution, was administered orally to each patient 1 hour after breakfast. Compared with data in healthy volunteers, the oral absorption and disposition of levocabastine were impaired in patients with renal insufficiency. The time to reach peak plasma concentration was increased and the peak plasma concentration was decreased in the patients with renal insufficiency compared with healthy volunteers. Urinary excretion of the unchanged drug, which is the major elimination pathway of levocabastine, was reduced in the patients with renal insufficiency. The decreased urinary excretion most likely contributed to the prolonged half-life (from 36 hours to 95 hours) and increased area under the plasma concentration-time curve (+56%) in the patients with renal insufficiency as compared with the healthy volunteers. Although the 6-hour hemodialysis procedure starting 4 hours after dosing eliminated 10% of the oral dose, the terminal half-life and the total area under the plasma concentration-time curve did not differ significantly between the hemodialysis and the nonhemodialysis patients. In conclusion, the current study showed that the initial oral absorption of levocabastine is reduced and that levocabastine elimination is prolonged in patients with renal insufficiency.

Adult↗
PubMed1993

Pharmacokinetics of the novel antipsychotic agent risperidone and the prolactin response in healthy subjects.

The pharmacokinetics of a novel antipsychotic agent, risperidone, and the prolactin response were studied in 12 dextromethorphan-phenotyped healthy men after administration of 1 mg risperidone intravenously, intramuscularly, and orally. The formation of the equipotent major metabolite, 9-hydroxyrisperidone, exhibited CYP2D6-related polymorphism. The plasma area under the concentration-time curve from time zero to infinity ratio of 9-hydroxyrisperidone to risperidone averaged 3 (intravenous and intramuscular) and 6 (oral administration) in the extensive metabolizers and 0.2 in the poor metabolizers. Risperidone half-life was about 3 hours in extensive metabolizers and 22 hours in poor metabolizers. Risperidone absolute oral bioavailability was 66%. The pharmacokinetics of the active moiety (risperidone plus 9-hydroxyrisperidone) varied little among subjects (mean terminal half-life, 20 +/- 2 1/2 hours; absolute oral and intramuscular bioavailability, 100%). The prolactin response correlated best with the plasma active moiety, which showed little hysteresis. It is concluded that risperidone metabolic polymorphism on increased plasma prolactin is minimal and that the active moiety is clinically relevant.

Adult↗
PubMed1993

Human herpesvirus 6 DNA in peripheral blood cells and saliva from immunocompetent individuals.

Human herpesvirus 6 (HHV-6) genome equivalents were quantitated in peripheral blood mononuclear cells (PBMCs) and saliva from 20 healthy individuals by the polymerase chain reaction (PCR). Nineteen of 20 subjects (95%) harbored HHV-6 DNA: 18 (90%) had HHV-6 in their PBMCs and 18 had HHV-6 in their saliva. Quantitative PCR revealed HHV-6 DNA levels ranging from negative to 4,000 HHV-6 genome equivalents per 10(6) PBMCs and from negative to 200,000 HHV-6 genome equivalents per ml of saliva. Longitudinal saliva samples from 15 HHV-6-seropositive subjects revealed salivary HHV-6 DNA persistence in 13 subjects. HHV-6 antibodies were detected in 17 of 19 subjects, with titers ranging from 1:400 to 1:51,200 (geometric mean titer, 1:2,500). Antibody titers did not correlate with HHV-6 DNA levels in PBMCs or saliva (P = 0.27 and P = 0.44, respectively). One subject with persistent HHV-6 DNA lacked detectable HHV-6 antibodies. The high prevalence of HHV-6 DNA in PBMCs and saliva supports the concept that HHV-6 exists at these sites in normal individuals.

Adult↗
PubMed1992

Dose proportionality study of loperamide following oral administration of loperamide oxide.

The pharmacokinetics of loperamide, after oral administration of increasing doses (1 to 16 mg) of loperamide oxide, has been investigated in 10 healthy male volunteers, using a randomised cross-over design. Comparison of the maximum plasma loperamide concentration and AUC demonstrated that the bioavailability of loperamide was proportional to the dose of loperamide oxide administered.

Administration, Oral↗
PubMed1992

Coamplified positive control detects inhibition of polymerase chain reactions.

Polymerase chain reactions (PCR) may fail to react because the substrate DNA is absent (true negative) or because of inhibition of specific amplification (false negative). The use of positive controls can increase confidence in negative PCR results by ruling out failure due to inhibition as a cause of the lack of amplification products. This report describes the construction and application of coamplified positive controls for herpes simplex virus and human herpesvirus 6 amplifications. Herpes simplex virus and human herpesvirus 6 PCR products were modified to generate control PCR products in which the original probe sequences were replaced by a Drosophila probe sequence. Implementation of the coamplified controls increased our specimen throughput in comparison with the parallel control amplifications used previously. Clinical laboratories using PCR for diagnosis of infectious diseases may find positive controls particularly helpful for increasing confidence that negative amplifications represent truly negative specimens.

Base Sequence↗
PubMed1991

Pharmacokinetics of ritanserin in patients undergoing hemodialysis.

The pharmacokinetics of ritanserin were studied in five patients with chronic renal insufficiency and who were undergoing periodic hemodialysis. Immediately after breakfast, a single 10-mg ritanserin tablet was administered to each patient on a day that they did not undergo dialysis. Plasma ritanserin levels were measured by a specific high-performance liquid chromatographic assay sensitive to 2 ng/mL plasma. After the oral 10-mg dose, the average time to reach the peak plasma concentration, Tmax, was 4.4 +/- 2.2 hours in these uremic patients, with a range of 2 to 8 hours. The average peak plasma concentration was 73.6 +/- 26.9 ng/mL (range: 54.6-120.0 ng/mL). Compared with a previous study in healthy volunteers, the uremic patients had a slower absorption profile, with a 39% reduction in peak plasma concentration and mean delay of 2.5 hours in Tmax. The mean area under the plasma concentration-time curve for ritanserin (2031 +/- 636 ng.hr/mL) was 47% lower compared with that in healthy volunteers (3867 +/- 1413 ng.hr/mL). The observed delayed and lower ritanserin absorption in these uremic patients may be caused by the chronic use of antacids such as aluminum hydroxide and calcium carbonate in all patients and/or by concurrent pathologic changes in the gastrointestinal mucosa of these patients. The regular hemodialysis sessions every 2-3 days did not affect the elimination rate of ritanserin, as the terminal half-life in these patients (39 +/- 23 hr) is similar to that in healthy volunteers (41 +/- 14 hr).

Administration, Oral↗
PubMed1991

Localization of immunogenic domains in the human immunodeficiency virus type 2 envelope.

Highly immunogenic domains have not yet been defined in the extracellular protein of the human immunodefiency virus type 2 (HIV-2) envelope. In this study, six contiguous segments covering the entire HIV-2ST envelope were amplified and cloned into a bacterial expression vector to localize the relative immunogenic reactivity of different regions of the molecule by Western blot (immunoblot) analysis. Our results demonstrate that the extracellular protein of the HIV-2 envelope contains highly immunogenic epitopes with potential value as type-specific markers for HIV-2 infection.

Africa, Western↗
PubMed1990

Comparative bioavailability of a cisapride suppository and tablet formulation in healthy volunteers.

The comparative bioavailability of cisapride as a 30 mg suppository and three 5 mg oral tablets was investigated in 12 non-smoking, healthy male volunteers. The two formulations were administered on two separate occasions following an overnight fast, according to a randomized cross-over design. The plasma concentration of cisapride was measured over 48 h after drug administration. The 30 mg suppository exhibited a mean time to the peak plasma concentration of 3.8 h, while the tablets showed a significantly earlier peak time of 1.5 h. The maximum plasma concentration of cisapride after the 30 mg suppository (50.3 ng.ml-1) was significantly lower than after the tablets (74.3 ng.ml-1). The AUCs following the two treatments did not differ significantly from each other. The comparative bioavailability of the 30 mg cisapride suppository in relation to the three 5 mg oral tablets was 85%, with a 95%-confidence interval of 67% to 102% (not adjusted for dose). Normalizing the mean AUC by dose, the relative bioavailability of the suppository was 43% of that of the tablet. The elimination half-life of cisapride was not significantly different following the administration of the two formulations (9.3 h for the suppository and 9.8 h for the tablet).

Adult↗
PubMed1990

Nonlinear pharmacokinetics and interconversion of prednisolone and prednisone in rats.

The pharmacokinetics of prednisolone and prednisone were examined in 32 rats at four intravenous doses (5, 10, 25, and 50 mg/kg). Each rat was given one dose of either intravenous prednisolone or prednisone, and plasma concentrations of both compounds were measured by HPLC. Mammillary moment analysis showed the apparent clearance and volume of distribution of prednisolone and the apparent clearance of prednisone to be dose-dependent. Further diagnostic analysis using a linear interconversion model revealed modest interconversion between the two steroids and at least two saturable clearance processes: the conversion of prednisolone to prednisone and the irreversible elimination of prednisone. A comprehensive model which incorporates the nonlinear clearances of prednisolone and prednisone plus the additional feature of nonlinear tissue distribution of prednisolone was then constructed. Four differential equations describing the rate of change of each steroid in each compartment were used to numerically fit by nonlinear least squares analysis all plasma concentration-time profiles simultaneously. The final estimates from the full model only partly agreed with the results from the two moment analyses but confirmed the general structure of the model. The nonlinear tissue distribution of prednisolone was reinforced by assay of muscle tissue. This study demonstrates the utility of the model-building process where simpler models yield insights into more elaborate schemes with complex nonlinear features.

Analysis of Variance↗
PubMed1990

Epstein-Barr virus genotypes associated with nasopharyngeal carcinoma in southern China.

We have used probes representing approximately two-thirds of the Epstein-Barr virus (EBV) genome to examine genetic polymorphism of wild-type EBV directly detected in 28 nasopharyngeal carcinoma (NPC) tissues from Southern China. In the hypervariable regions containing reiterated sequences, this analysis showed that while naturally occurring viruses are genetically diverse, only one genotype was detectable in each tumor specimen. Unique variants in NPC were detected in four regions of the EBV genome. Two of these appeared significant in their distribution. The type C variant resulting from loss of a BamHl site between the BamHl W1* and l1* regions was prevalent among isolates from Southern China, but not so common in the United States. An "f" variant having an extra BamHl site in the BamHl F region was almost exclusively detected in only Asian NPC biopsies.

Biopsy↗
PubMed1990

A chromosomal Agrobacterium tumefaciens gene required for effective plant signal transduction.

The vir gene products of Agrobacterium tumefaciens carry out the transfer of T-DNA to the plant genome. Effective transcriptional induction of the vir genes by plant signal molecules is controlled by two vir gene products, VirA and VirG. In this study we have identified and cloned a chromosomal region which is also required for vir gene induction. Transposon insertions within this region reduce induction significantly and strongly attenuate virulence, resulting in a restricted host range for infection. The reduction in vir gene transcription can be partially overcome by high concentrations of the inducer molecule acetosyringone. Expression of virG at low pH and low phosphate concentrations, which is independent of plant signals, is not affected by these mutations. Sequence analysis of the region revealed two divergent open reading frames, which we have designated chvE and ORF1. Several transposon insertions mapped in chvE; this resulted in attenuated virulence. chvE codes for a putative protein which is homologous to two periplasmic receptor proteins involved in chemotaxis and uptake of sugars. Whether ORF1 is required for virulence is uncertain. One transposon insertion resulting in avirulence maps in or near the 5' end of ORF1, and several which do not affect virulence map in its 3' end. ORF1 codes for a putative protein which is homologous to a family of transcriptional activator proteins.

Acetophenones↗
PubMed1989

[Dermatoglyphics parameters and cluster analysis of seven minority nationalities].

This paper reports the normal values of dermatoglyphics parameters of seven minority nationalities in Yunnan Province which are Bai, Blang, Yi, Hui, Lisu, Nu and Jinuo. The test of difference signification and cluster analysis show different parameters in several nationalities and the greatest most remarkable difference between Jinou and other nationalities. Han is very different from several nationalities. In each nationality, the symmetry pattern of same name finger or area is highly unanimous, the symmetry between left and right does not show random combination.

China↗
PubMed1989

[Studies on the teratogenic potential of 2,2'-methylenebis (4-ethyl-6-tert-buthylphenol) in rats].

2,2'-Methylenebis (4-ethyl-6-tert-buthylphenol), an antioxidant, was given orally to pregnant Wistar rats by stomach intubation at the dose levels of 187, 375 or 750 mg/kg body weight during days 7 to 17 of gestation, and the effects of the compound on dams and fetal development were examined. In dams at the two higher doses of 375 and 750 mg/kg, toxic signs such as hair fluffing and diarrhoea were observed, and their body weight gain and food consumption were suppressed. Two dams which showed marked diarrhoea in the highest dose group of 750 mg/kg died. However, there was no evidence of fetal malformations attributable to the treatment of the compound in any of the dose group tested, though a slight increase in fetal death was found in the highest dose group. It is concluded that 2,2'-methylenebis (4-ethyl-6-tert-buthylphenol) has a weak lethal effect on fetal development but not a teratogenic effect in the rat.

Abnormalities, Drug-Induced↗