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H Liu

Publications and source records attributed to H Liu.

At least 1,117 records · Page 62Linked to original sources
PubMed1993

Relationships in the Drosophila obscura species group, inferred from mitochondrial cytochrome oxidase II sequences.

We compare the sequences for the mitochondrial cytochrome oxidase II gene of 13 species of the Drosophila obscura group. The survey includes six members of the D. affinis subgroup, four of the D. pseudoobscura subgroup, and three of the D. obscura subgroup. In all species, the gene is 688 nucleotides in length, encoding a protein of 229 amino acids plus the first position T of the stop codon. The sequences show the typical high-transition bias for closely related species, but that bias is essentially eliminated for species pairs of > 5% sequence divergence. The phylogenetic relationships in the species group are inferred using both neighbor-joining and maximum parsimony. The two procedures give comparable results, showing that the D. affinis and D. pseudoobscura subgroups are monophyletic groupings that appear to have closer affinities to one another than either has to the D. obscura subgroup. We use transversion distances to estimate times of divergence, on the basis of three different estimates of the time of separation of the D. obscura species group from the D. melanogaster group. If that event occurred 35 Mya, then we can estimate the origin of the nearctic forms at approximately 22 Mya and the separation of the D. affinis and D. pseudoobscura subgroups at approximately 17 Mya.

Animals↗
PubMed1993

Temporal sequence of plaque formation in the cerebral cortex of non-demented individuals.

One of the hallmarks of Alzheimer's disease is the presence of argyrophilic plaques (arg-P) accompanying dementia and other forms of cognitive alterations. In the present investigation 195 non-demented, cognitively normal patients were grouped according to the presence or absence of critical coronary artery disease (cCAD), defined as a 75% or greater stenosis of one of the epicardial arteries. None of the subjects had significant cerebral vascular disease. The parahippocampal gyrus (PHG) and frontal pole were analyzed for the presence of arg-P, A4 deposition, ALZ-50 immunoreactive (IR) neurons and neuropil threads (NT). Individuals with cCAD have a significantly greater incidence of plaques than non-heart disease (non-HD) subjects. Every cCAD subject had ALZ-50 IR neurons in the PHG and a greater incidence of NT as compared to the non-HD subjects. Every subject with plaques also had IR neurons and NT in the PHG. Based on the presumption that early neurodegeneration labeled by ALZ-50 antibody and amyloid deposition are in some way linked, then the sequence of plaque formation is initiated by the presence of ALZ-50 IR neurons followed in order by NT, A4 deposition and diffuse form arg-P.

Adult↗
PubMed1993

Determination of total and free carbamazepine and the principal metabolites in serum by high-performance liquid chromatography with photodiode-array detection.

A precise and accurate high-performance liquid chromatography (HPLC) method has been established for the simultaneous analysis of carbamazepine (CBZ), carbamazepine-10,11-epoxide (CBZ-E), and trans-10,11-dihydroxy-10,11-dihydro-CBZ (CBZ-H) in serum samples and their ultrafiltrates. CBZ and its metabolites are eluted in a 3-microM ODS-Hypersil column (250 x 2 mm) at a column temperature of 40 degrees C. The mobile phase is a mixture containing potassium phosphate buffer-acetonitrile-methanol (110:50:30, vol/vol/vol) at a flow rate of 0.2 ml/min. Signals are monitored by a photodiodearray detector with a main sample wavelength of 215 nm and a bandwidth of 10 nm. Coefficients of variation (CVs) for within- and between-day are within 5%, with the recovery rates ranging from 98.16 to 104.64%. This method has the necessary sensitivity and linearity for routine therapeutic monitoring of both total and free CBZ and its principal metabolites. Total serum concentrations of CBZ, CBZ-E, and CBZ-H obtained from 55 epileptic children were 12.58 +/- 4.42, 2.45 +/- 1.22, and 5.83 +/- 3.17 (mean +/- SD, micrograms/ml), respectively. Levels of free CBZ, CBZ-E, and CBZ-H were 2.59 +/- 0.93, 1.05 +/- 0.57 and 3.73 +/- 1.87, respectively. Free fractions of CBZ, CBZ-E, and CBZ-H were 20.98 +/- 4.34, 42.63 +/- 8.21, and 65.41 +/- 7.80%, respectively. CBZ-H and CBZ-E had larger CVs than did CBZ (54.34 and 49.75 vs 35.15%, respectively, for total levels, and 50.31 and 54.46 vs 36.22%, respectively, for free levels), as well as higher free fractions. Determination of both total and free concentrations and free fractions of CBZ and its metabolites, as well as their ratios, should provide additional needed information for therapeutic drug monitoring of CBZ.

Carbamazepine↗
PubMed1993

Immunoregulatory effects of superantigens: interactions of staphylococcal enterotoxins with host MHC and non-MHC products.

Staphylococcus aureus carries a highly conserved set of genes which encode a set of secreted enterotoxins. Although it is likely that these enterotoxins affect the host/parasite in favor of the bacterium, we do not understand the molecular basis of this interaction. We summarize recent evidence that defines two types of interaction between the bacterial toxin and host cellular receptors that may subvert the host immune response to S. aureus. An interaction between the toxin and class II products on APC can result in inhibition of costimulatory activity and thus impair clonal expansion of T cells specific for bacterial antigens. Studies using anti-class II antibodies suggest that this may reflect transmission of a negative signal to APC after ligation of class II products. A second interaction between a subset of toxins, including SEC, with non-MHC products stimulates both T-cell proliferation as well as toxin-specific cytotoxic T cells (CTL). We put forward the hypothesis that this interaction reflects binding of a VCAM-1-like subsequence of SEC to VLA-4 expressed by activated target cells. We suggest that this interaction may serve to inhibit the host response by subversion of lymphocyte homing to sites of infection by SEC-producing staphylococci and by local elimination of (VLA-4+) memory T cells.

Amino Acid Sequence↗
PubMed1993

Structure of human rhinovirus complexed with Fab fragments from a neutralizing antibody.

We have determined the structure of a human rhinovirus (HRV)-Fab complex by using cryoelectron microscopy and image reconstruction techniques. This is the first view of an intact human virus complexed with a monoclonal Fab (Fab17-IA) for which both atomic structures are known. The surface area on HRV type 14 (HRV14) in contact with Fab17-IA was approximately 500 A2 (5 nm2), which is much larger than the area that constitutes the NIm-IA epitope (on viral protein VP1) defined by natural escape mutants. From modeling studies and electrostatic potential calculations, charged residues outside the neutralizing immunogenic site IA (NIm-IA) were also predicted to be involved in antibody recognition. These predictions were confirmed by site-specific mutations and analysis of the Fab17-IA-HRV14 complex, along with knowledge of the crystallographic structures of HRV14 and Fab17-IA. The bound Fab17-IA reaches across a surface depression (the canyon) and meets a related Fab at the nearest icosahedral twofold axis. By adjusting the elbow angles of the bound Fab fragments from 162 degrees to 198 degrees, an intact antibody molecule can be easily modeled. This, along with aggregation and binding stoichiometry results, supports the earlier proposal that this antibody binds bivalently to the surface of HRV14 across icosahedral twofold axes. One prediction of this model, that the intact canyon-spanning immunoglobulin G molecule would block attachment of the virus to HeLa cells, was confirmed experimentally.

Antibodies, Monoclonal↗
PubMed1993

Effects of smoked substance abuse on nonspecific airway hyperresponsiveness.

Previous data suggest that regular tobacco smoking may lead to nonspecific airway hyperresponsiveness (AHR) independent of airway obstruction, possibly because of effects on bronchial inflammation or mucosal permeability. Little is known concerning the effects on AHR of other widely smoked substances besides tobacco such as marijuana or cocaine. The smoke of both marijuana and cocaine contains respiratory irritants that elicit cough and produce abnormalities in airway dynamics and bronchial mucosal histopathology in habitual smokers. Therefore, regular smoking of one or both of these illicit substances could cause AHR or augment the AHR associated with tobacco smoking. The present study examined the influence of habitual smoking of marijuana, cocaine, and/or tobacco on nonspecific AHR in 542 (456 male) healthy participants (mean age, 34.8 +/- 6.8 SD yr) in an ongoing cohort study of the pulmonary effects of habitual smoking of illicit substances. Subjects with a history of intravenous drug abuse, significant occupational exposures, asthma, or recent upper respiratory tract infection were excluded. Inhalation challenge studies were performed using solutions of diluent and methacholine chloride (1.25 to 25 mg/ml) aerosolized by a DeVilbiss no. 646 nebulizer attached to a breath-activated dosimeter inhaled by three to five inspiratory capacity breaths. Positive responses to methacholine were defined by > or = 20% or > or = 10% declines in FEV1 from the postdiluent control value after inhalation of each concentration of methacholine. Participants were categorized by smoking status (nonsmoking and smoking of marijuana, cocaine, and/or tobacco alone and in combination); most analyses were performed in men and women separately.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Comparative efficacy of pivmecillinam and cotrimoxazole in acute shigellosis in children.

In a prospective randomized double-blind trial, pivmecillinam was compared with cotrimoxazole (TMP-SMX), both given orally for a period of 5 days, for the treatment of 59 children with shigellosis. 29 patients were treated with pivmecillinam and 30 with cotrimoxazole. 14% of shigella organisms isolated were resistant to pivmecillinam and 21% to TMP-SMX. The diarrhea persisted for a mean (+/- SD) period of 74 +/- 24.8 h in the pivmecillinam-treated patients versus 73.8 +/- 34 h in the TMP-SMX-treated patients. Duration of fever, positive stool culture, visible blood, occult blood, and pus cells in the stools were similar for both treatment groups. Five patients (17%) in the pivmecillinam group and 4 patients (13%) in the cotrimoxazole group fulfilled the clinical criteria that defined treatment failure. One patient (3.4%) in the pivmecillinam group and 2 (6.6%) in the TMP-SMX group evidenced recurrence of the diarrheal symptoms at the follow-up visit. No major drug-related side effects were observed in either group. We concluded that pivmecillinam is equivalent to cotrimoxazole in the treatment of shigellosis in children.

Acute Disease↗
PubMed1993

[Phospholipid components in BALFS from bleomycin induced pulmonary fibrosis in rats].

Qualitative and quantitative analysis was performed on 5 components of phospholipids (PL) isolated from bronchoalveolar lavage fluid (BALF) during the development of bleomycin induced pulmonary fibrosis in rats with high-performance liquid chromatography (HPLC). The measurement of cells and protein in BALF, the pathologic and morphometric observation with light and electronic microscope were also done. Results indicated that the changes both in BALF cells and in lung histopathology were similar, the amount of protein in BALF increased, the total amount of PL in BALF increased more than 1.8-fold over control animals at days 28 after administration of Bleomycin, phosphatidylglycerol (PG) decreased with time, phosphatidylinositol (PI) and phosphatidylethanolamine (PE) increased, PG/PI ratio decreased, the PG/PI ratio could be used as a marker for pulmonary fibrosis.

Animals↗
PubMed1993

[Clinical and pathological analysis on 44 cases of lid haemangioma].

Forty four cases of lid haemangioma are reported. 6 cases were diagnosed as cavernous haemangioma and treated by sclerosis therapy. The postoperative pathology examination to the other 38 cases showed that there were 9 cases of capillary haemangioma, 18 cases of cavernous, 8 cases of benign haemangioendothelioma, 1 case of racemose and 2 cases of mixed type. The age of these patients ranged from 2 months to 60 years and the disease history from 6 days to 26 years. From the clinical and pathological aspects the angioma is briefly discussed. The result suggest that the recurrence of the tumor may be associated with enlarged and deformed nutritious vessels. We advocate that the operation should be performed as early as possible.

Adolescent↗
PubMed1993

[Xianbai buyang Huanwu decoction used for treating hypertension with kidney qi deficiency and blood stasis].

UNLABELLED: 80 patients of presenium hypertension with geriatric Kidney Qi Deficiency and Blood Stasis were randomly divided into two groups. (1) Traditional Chinese Medicine group (TCMG, 50 cases) treated with Xianbai Buyang Huanwu Decoction (XBH); (2) Western medicine group (WMG, 30 cases) treated with compound hypotensor tablets and gamma-evening primrose-E oil capsules. RESULTS: The difference between the two groups was not significant (P > 0.05). After treatment, in TCMG, serum cholesterol and triglyceride, fibrinogen, whole blood viscosity and plasma viscosity, plasma and erythrocyte LPO activity lowered significantly, and plasma SOD and erythrocyte SOD raised significantly (P < 0.001-0.05), while in WMG, only showed the plasma LPO dropped (P < 0.05). The results suggested that XBH has the effects of reducing blood pressure, lowering the blood lipid, improving hemorrheological parameters and antioxidation.

Aged↗
PubMed1993

[Studies on CD spectra of derivatives of shikonin and alkannin].

The circular dichroism (CD) and electronic absorption spectra of seven derivatives of shikonin and alkannin isolated from the roots of Onosma confertum W.W. Smith (from Sichuan) and Arnebia euchroma (Royle) Johust (from Xinjiang) were described. Each pair of CD spectra obtained was exact mirror images and the UV spectra of these compounds were very similar. In comparison with the CD spectra of shikonin given in literature, the configuration of the pigments from Sichuan was assigned R and from Xinjiang were all S.

Circular Dichroism↗
PubMed1993

[Morphometric evaluation on the pathologic changes in ovariectomized endometria influenced by estrogen use].

Thirty SD female rats were divided into the following groups: (1) sham operation; (2) bilateral ovariectomized (OVX); (3) OVX and estrogen-treated (E). Computerized Image Analyser was used to evaluate the pathologic changes of endometria in these animals. The results showed the endometria of OVX group was in the state of atrophia, while the endometria of E group was in the state of early proliferative stage. The heights of endometria, endometrial epithelia cells and gland epithelia cells, the volume fraction and numerical density of endometrial glands, and the cavity diameter of the glands could effectively express the proliferative changes of the endometria. It is suggested that this method be used to study the pathology of the different endometric diseases.

Animals↗
PubMed1993

Thymic carcinoid tumor--a report of 7 cases.

The thymic carcinoid tumor is a rare neoplasm which is often clinically misdiagnosed as thymoma. But the two differ in origin, biological behavior, accompanying syndromes, pathological features, and prognosis. The characteristics of the thymic carcinoid tumor are: difficulty in diagnosis, high malignancy, frequent recurrence and extrathoracic metastasis over a prolonged period postoperatively. Complete surgical resection of original and recurrent tumors is the important treatment. Microscopic, electron microscopic and immunohistochemical examinations may be required in making an accurate pathological diagnosis. This paper reports 7 cases of thymic carcinoid tumor.

Adult↗