Search PubMed⌕ Search

Biomedical subjects

T Wang

Publications and source records attributed to T Wang.

At least 865 records · Page 48Linked to original sources
PubMedDate not supplied

Structural aspects of a placenta from a case of maternal acute lymphatic leukaemia.

After delivery of a healthy female child from a mother suffering from acute lymphatic leukaemia (35th week of gestation) the placenta was examined by light and electron microscopy. Morphologically, the villi in this placenta from a case of maternal acute lymphatic leukaemia differed from those in a normal placenta in the following respects: 1. The frequent occurrence of fibrinoid deposits on the free surface of the syncytiotrophoblast and the pronounced formation of syncytial cytoplasmic protrusions. 2. Dilatation of syncytial rough endoplasmic reticulum, numerous syncytial knots and numerous autophagosomes. 3. An excessive number of villous cytotrophoblastic cells. 4. Thickening of the trophoblastic basement membrane. 5. Bulbous endothelial cells with cytoplasm in fetal capillaries. 6. Strands of basement membrane-like material within the villous stroma. 7. Phagocytosis of nucleus-containing cells by the syncytiotrophoblast. 8. Cells with an abundant number of microtubular bundles within the villous stroma. It is suggested that phagocytosis of nucleus-containing cells (tumour cells?) by the syncytium could play a role in the prevention of transplacental metastasis.

Adult↗
PubMedDate not supplied

3DFS: a new 3D flexible searching system for use in drug design.

This paper describes a new 3D flexible searching system 3DFS which supports two types of query definitions: simple atom-based definition and generalized function-based definition. The simple and practical definitions of hydrogen bond acceptors/donors, charge centers, aromatic ring centers, and a rapid hydrophobe recognition algorithm are described in detail. 3DFS adopts a four-step searching strategy: a rapid ID screening, an exact 2D substructure searching using the GMA algorithm, a rigid 3D searching, and a conformationally flexible 3D searching using POWELL method. The utility of 3DFS is illustrated by several typical searching examples.

Chemical Phenomena↗
PubMedDate not supplied

Sexual problems among women and men aged 40-80 y: prevalence and correlates identified in the Global Study of Sexual Attitudes and Behaviors.

The Global Study of Sexual Attitudes and Behaviors (GSSAB) is an international survey of various aspects of sex and relationships among adults aged 40-80 y. An analysis of GSSAB data was performed to estimate the prevalence and correlates of sexual problems in 13,882 women and 13,618 men from 29 countries. The overall response rate was modest; however, the estimates of prevalence of sexual problems are comparable with published values. Several factors consistently elevated the likelihood of sexual problems. Age was an important correlate of lubrication difficulties among women and of several sexual problems, including a lack of interest in sex, the inability to reach orgasm, and erectile difficulties among men. We conclude that sexual difficulties are relatively common among mature adults throughout the world. Sexual problems tend to be more associated with physical health and aging among men than women.

Adult↗
PubMedDate not supplied

Mechanistic aspects of chiral discrimination on an amylose tris(3,5-dimethylphenyl)carbamate.

The separation of [2R-[2alpha(R*),3alpha]]-5-[[2-[1-[3,5-bis-(trifluoromethyl)phenyl]ethoxy]-3(S)-4-fluorophenyl)4-morpholinyl]-methyl]-N,N-dimethyl-1H-1,2,3-triazole-4-methanamine hydrochloride from its enantiomer was achieved on an amylose tris-3,5-dimethylphenyl carbamate stationary phase. The retention of the enantiomers is dominated by weak hydrogen bonds while the enantioselectivity is governed by other kinds of interactions, e.g., inclusion in the amylose carbamate chains. Van't Hoffplots of 1nalpha vs. reciprocal temperature were non-linear and could be divided into two linear regions. One region at low temperature (5 degrees C- approximately 20 degrees C) and another one between 25 degrees C-70 degrees C with the change in slope occurring between 16 degrees C and 20 degrees C. DSC experiments suggested that the behavior can be attributed to breakage of H-bonds triggering a conformational change. Molecular simulation indicated a correlation between the interaction energies and the elution order obtained experimentally. The most retained enantiomer (R,R,S-enantiomer) interacts with the stationary phase through a hydrogen bond between the triazole proton and the C=O groups of the stationary phase, as well as through an inclusion in the cleft of the stationary phase. The other enantiomer exhibits a bifurcated H-bond between the triazolic proton and the C=O groups of the stationary phase leading to a less stable complex.

Journal Article↗
PubMedDate not supplied

Cardiovascular regulation during anoxia in the turtle: an in vivo study.

This study describes the integrated cardiovascular response of instrumented turtles to acute anoxic exposure (approximately 2 h) and also determines the factors that regulate these responses. Trachemys scripta were chronically implanted with ultrasonic blood flow probes for the measurement of total pulmonary and systemic blood flows and heart rate. In addition, catheters were implanted into the right aortic arch for the measurement of systemic blood pressure, arterial blood gases, and pH. Animals were free to swim within an aquarium but could only breathe within a small chamber located at the surface. Cardiovascular variables were continuously monitored during normoxia, 2 h of anoxia, and during recovery at normoxia. In addition, some animals were treated with atropine or epinephrine during the anoxic exposure. During the onset of nitrogen breathing there was an increase in ventilation frequency, heart rate, pulmonary blood flow, and systemic blood flow and the development of a net left-to-right cardiac shunt. These changes lasted up to 1 h, followed by bradycardia (heart rate was reduced by 50% from control values) and the development of a large net right-to-left shunt (approximately 80% of the total cardiac output). These changes lasted the duration of the anoxic exposure and were rapidly reversed on return to a normoxic environment. Injections of epinephrine during anoxia had no effect on heart rate, pulmonary blood flow, or systemic blood flow. In contrast, injection of atropine during anoxia resulted in an increase in the heart rate and systemic blood flow, suggesting that the anoxic cardiac response is partially mediated through cholinergic mechanisms.

Acute Disease↗
PubMedDate not supplied

Molecular mapping of Rxp conditioning reaction to bacterial pustule in soybean.

The Rxp locus in soybean [Glycine max (L.) Merr.] that conditions reaction to bacterial pustule was mapped by simple sequence repeat (SSR) marker analysis. A population of 116 F4-derived lines from a cross between the resistant parent Young and the susceptible parent PI 416937 was used for mapping. The Rxp locus was mapped 3.9 cM from Satt372 and 12.4 cM from Satt014 on linkage group D2. Linkage associations were confirmed by identifying a close association between the SSR genotype at each locus identified as flanking Rxp and the bacterial pustule reaction of individual lines derived from a population different from the one used for mapping. A molecular pedigree analysis showed that bacterial pustule-resistant cultivars inherited the resistance gene rxp from the ancestral cultivar CNS based on their consistent genotypic pattern at flanking marker loci. Based on the results of the study, marker-assisted selection for rxp would be very effective.

Bacterial Toxins↗
PubMedDate not supplied

Optimization and assessment of the in vivo efficacy of a heparin removing bio-reactor using mathematical modeling.

The authors previously reported an approach that could be used to simultaneously control both heparin and protamine induced complications during extracorporeal perfusion. The approach consists of placing a hollow fiber based bio-reactor containing immobilized protamine (defined as the "protamine bio-reactor") at the distal end of the blood perfusion circuit for extracorporeal heparin removal. Preliminary in vitro and in vivo studies have successfully demonstrated the feasibility of the proposed approach. The authors present an in vivo theoretical model for this extracorporeal heparin removal approach. This model, which consists of a two compartment model for the metabolic clearance of heparin and a plug flow reactor model for the protamine bio-reactor, can be used to optimize and assess the required size of the bio-reactor for effective clinical heparin removal. To examine the utility of such a model, 14 female mongrel dogs (six dogs were used as controls and eight dogs were used to test the bio-reactor) were included in the in vivo study. The femoral artery and femoral vein of the dog were cannulated, and the bio-reactor was attached. Heparin was given intravenously at a dose of 150 IU/kg body weight, and its activity was measured using the aPTT assay. Preliminary studies show that the experimental data fits remarkably well with the theoretical model. The model indicates that the protamine bio-reactor can remove heparin efficiently, even in the presence of competitive binding between heparin and plasma proteins. Under clinical situations, such as hemodialysis and open heart operations, a protamine bio-reactor containing approximately 45,000 hollow fibers is necessary to reduce heparin to less than 10% of its initial concentration. The time required to saturate the protamine bio-reactor with heparin is dependent upon the blood flow rate which, as predicted by the model, is 10 min for open heart surgery (flow rate = 2,000 ml/min) and 60 min for hemodialysis (flow rate = 200 ml/min). A detailed description of the in vivo model, as well as future directions envisioned in the design of a clinically useful heparin removing system are discussed.

Animals↗
PubMedDate not supplied

MSA-35: a protein identified by human autoantibodies that colocalizes with microtubules.

We have identified a putative 35-kilodalton protein that colocalizes with microtubules and displays a unique spatial and temporal distribution during the cell cycle of HeLa cells. This protein has been given the designation MSA-35. MSA-35 first appears in association with microtubules and centrosomes of interphase cells exhibiting centrosome separation as a prelude to cell division. This protein is found in conjunction with kinetochore microtubules throughout their appearance. MSA-35 transiently associates with interpolar microtubules following anaphase and the pattern of MSA-35 reactivity in telophase cells suggests that there are at least seven domains within the intercellular bridge. The distribution of MSA-35 during and following recovery from mitotic arrest with nocodazole suggest that it is also present at low levels in interphase cells, can associate with interphase centrosomes, and colocalizes with nascent microtubules. The complex spatial and temporal distribution of MSA-35 indicates that it may be necessary for a series of events in the mitotic process such as the bundling of microtubules.

Autoantibodies↗
PubMedDate not supplied

Tubule function in transgenic mice.

Many transporters involved in renal electrolyte transport have recently been identified and cloned. The availability of genetically manipulated mice, especially transgenic knockout and overexpression models, has made it possible to examine ion transport in kidney tubules in the absence of specific transporters whose function in defined tubule segments is well known. Such selective alterations in transport functions are also useful to investigate adaptive mechanisms by which the kidney compensates for specific transport lesions. Examples of mouse models displaying altered renal transport function include targeted disruption of genes encoding the Na-H exchanger isoforms NHE2 and NHE3, the thiazide-sensitive Na-Cl cotransporter TSC, CFTR, and the colonic isoform of the H,K-ATPase. Moreover, mice with null mutation in the Na-H exchanger isoform NHE1 have been also identified. In addition, a strain of mice with enhanced H,K-ATPase expression due to a defective endocytosis signal has been developed. Other transporter knockout models will soon become available. In this review we focus on the physiological characterization of renal tubule transport in animals with well-defined genetic transport lesions.

Angiotensin II↗
PubMedDate not supplied

Effects of glyburide on renal tubule transport and potassium-channel activity.

Renal clearance, microperfusion and patch-clamp techniques were used to investigate the effects of the K-channel blocker glyburide on electrolyte excretion, the transport properties of the thick ascending limb (TAL) of Henle and K-channel activity in the apical membrane of the TAL and of the cortical collecting tubule. Our data suggest that the K-channel blocker glyburide can inhibit transport of Na and K in the TAL by blocking K recycling across the apical membrane. Additionally, inhibition of K secretion in the collecting ducts occurs by decreasing the activity of apical K channels and prevents kaliuresis.

Animals↗
PubMedDate not supplied

Synthesis of prostaglandins and thromboxane B2 by cholesterol-fed rabbits.

Alterations in the synthesis of thromboxane A2 (TxA2) and prostacyclin have been implicated in the development of atherosclerosis. We measured the amounts of the degradation products of these substances, TxB2 and 6-oxo-prostaglandin F1 alpha (6-oxo-PGF1 alpha), respectively, as well as PGE2, that were synthesized by slices and the luminal surfaces of aortas from rabbits fed either a control diet or a diet supplemented with cholesterol and peanut oil. For these studies, we developed conditions that were designed to minimize the autoinactivation of cyclooxygenase during removal and preparation of the tissue. Pretreatment of aortas with a medium containing ibuprofen and EDTA resulted in an approximately twofold increase in 6-oxo-PGF1 alpha production upon subsequent incubation. Despite the increased lipid peroxidation associated with atherosclerotic lesions, we observed no changes in either aortic 6-oxo-PGF1 alpha production or in the levels of its major urinary metabolite, 2,3-dinor-6-oxo-PGF1 alpha, after as long as 15 weeks of dietary supplementation with cholesterol and peanut oil. Similarly, synthesis of PGE2 by aortic slices and the aortic lumen was the same in cholesterol-fed and control rabbits. In contrast to aortic 6-oxo-PGF1 alpha and PGE2 synthesis, there was a dramatic 10-fold increase in TxB2 released from slices of thoracic aorta after 15 weeks on the atherogenic diet. This was much greater than the approximately twofold increase in the synthesis of TxB2 by the luminal surface of the thoracic aorta, suggesting that the primary site of TxB2 synthesis in the aorta is in the inner part of the blood vessel.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMedDate not supplied

Heat shock protein antibody titers are reduced by statin therapy in dyslipidemic subjects: a pilot study.

Antibody titers to heat shock protein (Hsp)-60 and -65 are positively related to risk of vascular disease and cardiovascular endpoints. There are few data on the factors that regulate the levels of these antibodies. It is known that the statins have antiinflammatory and immunoregulatory properties. The authors examined the effects of 2 statins, simvastatin (Zocor) and atorvastatin (Lipitor) on antibody titers to Hsp-60, -65, and -70 in a group of dyslipidemic patients. Twenty patients attending a lipid clinic, and previously not receiving lipid-lowering treatment, were treated with 10 mg of simvastatin (n = 11) or atorvastatin (n = 9) for 4 months. An additional 14 patients were recruited from the same clinic at the same hospital as a control group. The medication of these latter patients was unaltered for 4 months and the same parameters were measured as for the statin group. Antibody titers to Hsp-60, -65, and -70 were measured by enzyme-linked immunosorbent assay and lipoprotein profile and highly sensitive serum C-reactive protein (CRP) were measured by routine methods before and after treatment. Pretreatment and posttreatment data were compared by paired t or Mann-Whitney tests. Overall statin treatment was associated with a significant reduction in median antibody titers to Hsp-60 (17.2%, p = 0.03), Hsp-65 (15.9%, p = 0.003) and Hsp-70 (8.3%, p = 0.006), but not in control patients. Both statins caused a reduction in median serum CRP concentrations (45% overall, p < 0.05), but significant changes were not observed in the control patients. The effects on Hsp antibody titers were not related to changes in serum CRP concentrations (p > 0.05). However, there was a significant correlation between changes in antibody titers to Hsp-60 vs Hsp-65 (p < 0.01), Hsp-60 vs Hsp-70 (p < 0.05), and Hsp-65 vs Hsp-70 (p < 0.001). Statin treatment was associated with a reduction in antibody titers to Hsp-60, -65, and -70. This reduction is not fully explained by the antiinflammatory effects of the statins but may be due to their other immunomodulatory properties.

Adult↗
PubMedDate not supplied

Internet resources for end-of-life care.

Numerous publications highlight the need for critically evaluating medical information on the Internet. This review identifies Internet resources specifically dedicated to end-of-life care. An annotated review of key web-based resources is presented. The Internet has the potential to catalyze the doctor-patient relationship toward true "partnership." Physicians and patients will benefit from using a focused research strategy.

Computer User Training↗
PubMedDate not supplied

Improving accuracy of bone resections using robotics tool holder and a high speed milling cutting tool.

The use of non-cemented prosthetic components in implant surgery is demanding a high quality of bone beds in order to allow for a good level of osseointegration. Two parameters are significant in the evaluation of the quality of the host bone: roughness, which reports on the presence of gaps and peeks, and flatness, which reports on the total percentage of bone which lies in a given interval from the prosthesis. Robot assisted cutting of 32 pig femours and tibiae was performed using various techniques and options. This paper demonstrates roughness and flatness can be taken of the order of the limits necessary for osseointegration, by using a milling cutting tool mounted on a strong support, in this case a robot arm, improving on the results obtained by similar studies referred to hand sawed bones by 10 times.

Analysis of Variance↗
PubMedDate not supplied

The use of improved silver impregnating staining method in the differential diagnosis of tuberculoid leprosy.

A comparative study on the usefulness of Kawatsu's silver impregnating staining method compared with S-100 protein ABC technique for the differential diagnosis of tuberculoid leprosy was carried out. The results of neurohistological examination obtained from both methods were almost the same. It can be said that Kawatsu's method is useful and cost-effective, and thus suitable for practical use in developing countries.

Diagnosis, Differential↗
PubMedDate not supplied

Histo-bacteriological investigation on borderline tuberculoid leprosy.

The multi-sections, which were stained by Fite method, of skin biopsies taken from twelve active BT cases were examined under the guidance of special stains for demonstration of nerve components. All cases were AFB positive. Bacilli were found in infiltrated nerves in 11 cases, of which, in 7 cases, bacilli were detected in nerve fragments within epithelioid cell granuloma. And bacilli were seen in arrector pili muscles in 2 cases. No bacilli were detected in other sites. Since the survival of M. leprae in nerves is one of the reasons causing relapse, this paper suggests that it would be better to treat active BT cases with multibacillary regimen recommended by WHO even though smear-negative.

Humans↗