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Biomedical subjects

N Wang

Publications and source records attributed to N Wang.

At least 325 records · Page 18Linked to original sources
PubMed1995

Evidence for coinfection by multiple strains of human immunodeficiency virus type 1 subtype B in an acute seroconvertor.

Sequences encoding the envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1) were amplified by PCR from plasma and peripheral blood mononuclear cells obtained at four time points from an acute seroconvertor. Genetic analyses, including nucleotide sequencing and heteroduplex mobility studies, showed that the patient harbored three distinct populations of HIV-1 clade B envelope sequences, with nucleotide distances ranging from 9.2 to 17.2%. One population of sequences was clearly distinguishable from the others on the basis of phylogenetic analysis. In addition, sequences suggesting recombination between two of the three distinct viral populations were also found. This case of acute seroconversion provides clear and conclusive evidence that coinfection by multiple HIV-1 strains can indeed occur in vivo.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Sequence diversity of V1 and V2 domains of gp120 from human immunodeficiency virus type 1: lack of correlation with viral phenotype.

We analyzed by PCR and direct sequencing 57 viral sequences from 47 individuals infected with human immunodeficiency virus type 1, focussing on the V1 and V2 regions of gp120. There was extensive length polymorphism in the V1 region, which rendered sequence alignment difficult. The V2 hypervariable locus also displayed considerable length variations, whereas flanking regions were relatively conserved. Two-thirds of the amino acid residues in these flanking regions were highly conserved (> 80%), presumably reflecting their critical contribution to V2 structure or function. We also characterized the syncytium-inducing properties of the isolates from which we derived sequence information. There was no correlation between V1 or V2 sequences and the viral phenotype, contrary to a previous report (M. Groenink, R. A. M. Fouchier, S. Broersen, C. H. Baker, M. Koot, A. B. van't Wout, H. G. Huisman, F. Miedema, M. Tersmette, and H. Schuitemaker, Science 260:1513-1516, 1993). The sequence heterogeneity described in this study provides information to suggest that it would be most difficult to exploit the V1 and V2 domains for vaccine development.

Amino Acid Sequence↗
PubMed1995

Urokinase receptor mediates mechanical force transfer across the cell surface.

The tripartite complex formed by the urokinase receptor, urokinase, and its inhibitor is an enzymatic system that controls plasmin formation involved in degradation of extracellular matrix proteins. With the use of magnetic twisting cytometry with urokinase-coated ferromagnetic beads, we applied mechanical stress directly to the urokinase receptor on the surface of human myogenic cells in culture. The stiffness and the stiffening response measured through the urokinase receptor resembled those of integrins, which are linked mechanically to the cytoskeleton. Furthermore, stiffness decreased with disruption of actin microfilaments. These results demonstrate that the urokinase receptor is coupled mechanically to the cytoskeleton. Inhibition of the tripartite complex formation with antibodies led to a twofold increase in cytoskeletal stiffness. A stiffened cytoskeleton might impede cytoskeletal remodeling and reorganization and thus impede cell motility. Our results demonstrate that the urokinase receptor mediates mechanical force transfer across the cell surface. As such, it is a novel pathway to regulate cytoskeletal stiffness and, thereby, possibly to modulate motility of normal and abnormal adherent cells.

Cell Membrane↗
PubMed1995

Arachidonic acid inhibits potassium conductances in cultured rat oligodendrocytes.

Arachidonic acid (AA) and its metabolites play a dual role as intracellular second messengers and as transcellular mediators of neural activity. We have previously shown that AA increases cytosolic Ca2+ in oligodendrocytes. In this work, we studied the effects of AA and other fatty acids on whole cell K+ currents of cultured rat oligodendrocytes using the patch-clamp technique. We found that 1) AA decreased the current amplitudes of both the inwardly rectifying K+ current (IKir) and the outward K+ currents (IKo) resulting in membrane depolarization; 2) AA also induced IKo current inactivation/blocked state; 3) AA appeared to act directly on K+ channels and not indirectly via its metabolic products, activation of protein kinase C, or by generation of oxygen free radicals. We have thus demonstrated an additional mechanism for AA-induced signaling in oligodendrocytes, i.e., via modulation of K+ conductances leading to membrane depolarization. The latter has been shown to influence protein phosphorylation and perhaps other important functional output of oligodendrocytes.

Animals↗
PubMed1995

The avian lung: is there an aerodynamic expiratory valve?

The unidirectional gas-flow pattern through the avian lung is thought to result from 'aerodynamic valves'; support for this hypothesis lies mainly in the failure to find any evidence for anatomical valves. During expiration, air flows from the caudal air sacs through the major exchange area of the lung, the paleopulmonic parabronchi, instead of bypassing the lungs via the intrapulmonary bronchus. We tested whether the effectiveness of this expiratory flow control mechanism depends on aerodynamic factors, especially convective inertial forces that depend on gas density and flow velocity. In pump-ventilated, anaesthetized geese, a bolus of tracer gas was introduced into both the right and left caudal thoracic air sacs during an end-inspiratory pause. During the first expiration, the rise of tracer levels within the caudal trachea was measured. Valve efficacy was positively correlated with the rate of expiratory gas flow, V·ao (range 8­200 ml s-1). At flows assumed to occur during exercise in geese (V·ao>100 ml s-1), the expiratory valve efficacy was approximately 95 %; it was less effective at lower flows. Surprisingly, the density (rho) of the background gas (rho of He/O2=0.43 g l-1, Ar/O2=1.72 g l-1 or SF6/O2=5.50 g l-1) had no effect on expiratory valving. We suggest two possible mechanisms that might explain this unusual combination of flow dependence without density dependence. (1) If airway geometry changes occurred between experiments with different gases, flow in the vicinity of the expiratory valve may have varied independently from flow measured at the airway opening. (2) Alternatively, valving may depend on dynamic compression of the intrapulmonary bronchus, which could depend mainly on viscous resistance and thus on flow velocity but not gas density.

Journal Article↗
PubMed1995

Establishment of a leukemic lymphocyte culture from human aqueous humor.

We have recently developed new techniques for culturing chronic lymphocytic leukemia (CLL) lymphocytes from human aqueous humor. We used leukemic lymphocytes collected from the aqueous humor of a patient with CLL and leukemic glaucoma. We grew these leukemic cells in combination with a feeder cell layer and other technical refinements. Microscopy and immunoassay indicate success in obtaining a homogenous population of B-type CLL cells through the 12th passage of the culture. No significant effect on cell growth was found with either of two mitogens (PWM and PHA), or between culture with and without autologous serum. Our new techniques for culturing leukemic cells derived from the aqueous humor provide a reliable resource for the study of chronic lymphocytic leukemia lymphocytes and leukemic glaucoma.

Animals↗
PubMed1995

The metabolic responses of slideboard exercise in females.

Recently, slideboard exercise training has been introduced as a mode of aerobic training. The purpose of the investigation was to determine the acute cardiovascular and metabolic responses to slideboard exercise. Subjects consisted of 20 healthy females with a mean age of 26.5 +/- 7.9 years, and a VO2max of 40.8 +/- 5.6 ml.kg-1.min-1. The results of the investigation showed that 10 min of a commercially produced slideboard routine elicited mean heart rate (HR) responses ranging from 160 to 168 beats.min-1 and VO2 values of 27.5 to 33.5 ml.kg-1.min-1. A sub-group of 10 subjects was also evaluated while performing sliding exercise at different sliding rates (SR). Subjects performed the standard slide technique at metronome cadences of SR-40, SR-50, and SR-60 slide.min-1. As sliding rate increased so did HR and VO2. The subjects demonstrated mean responses of approximately 55 to 81% of VO2max for the slower to the most rapid sliding rates, respectively. Compared to treadmill exercise at the same oxygen consumption levels, the heart rates for sliding were approximately 15% higher. Slideboard exercise can be an alternative mode of aerobic training.

Adult↗
PubMed1995

[A study on serotypes of U. urealyticum isolated from different populations].

This is a study on serotypes 1-14 Ureaplasma urealyticum (Uu) infections of genitourinary in different populations. The results show that 1) the Uu infection rate is the highest in sexually promiscuous persons with STDs (78/115, 67.83%), lesser in both sexually promiscuous persons without STDs (97/185, 52.43%) and in general population with common genitourinary infections (84/180, 46.67%), and the lowest in healthy controls (73/320, 22.81%); 2) all of the 14 serotypes and untypeable Uu infections existed in China are identified; 3) the relationship between Uu 1 and 4 serotype and infections is stronger, but medium strong in 2, 8 and 10 serotype, whereas, 3, 9 and 14 serotype are major colonizational strains; 4) multi-serotypes infections are closely associated with sexually promiscuous behaviour.

Adolescent↗
PubMed1995

[Treatment of extensive deep burn of scalp with full-thickness necrosis of calvarial bone].

From 1990 to 1993 eight patients suffering from extensive deep burn of scalp with full-thickness necrosis of calvarial bone were treated. The intra-cranial damage following electrical injury or prolonged contact with heat source, and the extent of skull necrosis were delineated by CT and bone scanning. Primary coverage of the exposed calvarial bone using musculo-cutaneous flap or free skin flap was done, leaving the necrosed skull in situ to serve as a scaffold of "creeping substitution" for bone regeneration. Primary healing of the wound was achieved in four cases. Three cases required an average of 2.6 times of curettage or excision of the infected bone. None of the cases required a late reconstruction of the skull in this group.

Adolescent↗
PubMed1995

Clinical studies of primary angle closure glaucoma.

The ocular anatomic features, pupil-blocking force, status of angle synechia closure and positivity of provocative tests were compared between the primary chronic angle closure glaucoma (PCACG) and primary acute angle closure glaucoma (PAACG) by ultrasonic biometry, computerized image processing technique of the anterior ocular segment, gonioscopy and provocative tests. The studies showed that the anterior chamber depth of PAACG was shallower than that of PCACG, the pupil-blocking force of PAACG was stronger than that of PCACG, the status of angle synechia closure of PCACG was mainly creeping synechia closure and the positivity of mydriasis test after iridectomy was much higher (37.93%) in PCACG than that (11.43%) in PAACG. These facts suggested that the mechanisms of the angle closure of more than half of PCACG cases be multiple, besides the mechanism of pupillary block. Therefore, the authors emphasize that the pupillary block must be eliminated as well as the other mechanisms for the treatment of PCACG. The criteria of diagnosis and principles of management of PCACG were proposed.

Adult↗
PubMed1995

One-stage primary repair of distal esophageal perforation using fundic wrap.

Esophageal leak following primary repair of esophageal perforation is a serious complication that can lead to severe mediastinitis and sepsis. Complete diversion with esophageal exclusion or resection is designed to minimize further mediastinal contamination. However, this approach is not necessarily associated with less morbidity or mortality. Furthermore, a second stage operation is required to restore esophageal continuity. From 1986 to 1994, we performed a one-stage primary repair of the distal esophagus in seven patients with either iatrogenic (n = 5) or spontaneous (n = 2) perforations and reinforced the repair by a fundic wrap. One patient underwent an additional modified Heller myotomy for achalasia. Delay between perforation and operation was less than 6 hours in 3 patients, 6 to 24 hours in 2 patients, and greater than 24 hours in 2 patients. Only one patient (14%) developed a small esophageal leak that spontaneously resolved with adequate mediastinal drainage, intravenous antibiotics, and aggressive nutritional support. One patient (14%), whose repair was delayed by 12 hours, died postoperatively of profound sepsis. This patient was moribund from sepsis preoperatively, and postmortem examination of the esophagus revealed no evidence of esophageal leak. Esophageal continuity was maintained in all patients. The median length of stay was 21 days (range, 15-58 days). We conclude that primary reinforced repair of esophageal perforation using a fundic wrap is an effective method of treatment for distal esophageal perforation, even when the repair is delayed by more than 24 hours.

Adult↗
PubMed1995

[The effects of synthetic oligopeptides on progesterone production in corpus luteum cell of rat and their mechanism of action].

The effects of a series of synthetic oligopeptides on progesterone production by rat CL cells were compared and their mechanism of actions was studied in vitro. The ones with inhibitory actions were characterized by carrying positive charge in the medium of pH 7.3-7.5 and with intermolecular linkage. A preliminary survey of the effect of the active oligopeptides on signal systems showed: (1)GY and YG inhibited PLC system; (2)GY and GSK reduced hCG-induced progesterone production in CL cells probably by regulating cellular Ca2+ concentration; (3) GSK decreased TPK activity and GYK increased it in hCG treated CL cell though both of them were inhibitory on progesterone production. GSK also stimulated PKC and supressed PKA activity in CL cells. The anti-progesterone effect of oligopeptides so far synthesized may influence either PKA or PKC or TPK systems. The mechanism of action at the molecular level is quite complicated.

Animals↗
PubMed1995

Analysis of tomato root initiation using a normal mixture distribution.

We attempt to identify the number of underlying physical phenomena behind tomato lateral root initiation by using a normal mixture distribution coupled with the Box-Cox power transformation. An initial analysis of the data suggested the possibility of two (possibly more) subpopulations, but upon taking reciprocals, the data appear to be very nearly Gaussian. A simulation study explores the possibility of erroneously detecting a second subpopulation by fitting data which are improperly scaled. A power calculation suggests that only unrealistically large sample sizes can detect the unbalanced mixtures one might expect with data of this type.

Biometry↗
PubMed1995

[The interstitial response and postoperation recurrent mechanism in liver cancer].

Immunoactive cell group markers and glycoproteins of extracellular matrix and basement membrane (fibronectin, laminin, type IV collage) in 156 human hepatocellular carcinomas and their surrounding tissues were localized with immunoperoxidase technique. T lymphocytes were the major immunoactive cells in the regions of local invasion in liver cancer. The distributing patterns of the glycoproteins were similar to the results of previous reports, mainly localized in the surrounding cancer cells, interstitium and vessel walls or sinusoids in tumor, and tumor capsule. The patients, whose hepatocarcinomas showed stronger cell immunoactivity (T and help T cells were in the majority) and higher expression of glycoproteins of extracellular matrix and basement membrane had a longer tumor-free survival (63.2 to 12.8 months) and lower recurrences (P < 0.01). Of the 156 patients 92.9%, 82.6%, 65.4%, 44.2% and 30.8% and 1, 2, 3, 4 and 5 postoperative tumor-free years respectively with a total currence rate of 53.2% (83 patients). In the 83 recurrences, 65 were intrahepatic subclinical, which were promptly reresected 78.3%, recurrence related factors included tumor number and size, capsule infiltration, and portal veins involvement. Being different from those with single node, capsulated hepatocellular carcinomas and multiple/daughter ones had invisible tumor cells disseminated to the remnant liver. Those without capsule infiltration had a low recurrence rate, which agrees to the hypothesis that capsules can bar the dissemination of tumor cells. Additional results show that postoperative tumor recurrence is mainly pertinent to histopathological characteristics of the primary focus. According to the phenomenon that nearly 63.1% of recurrent liver carcinomas are located at the ipsilateral segment of the primary ones, we emphasize that the occurrence and recurrence of liver carcinoma are mainly unicentral.

Adolescent↗
PubMed1995

[Study on antifertility mechanisms of tripchlorolide (T4)].

Hyaluronidase activities of testes and epididymides in rats were obviously inhibited by T4 po at dosage of 0.1 mg.kg-1/d for 7 weeks. T4 at dosage of 0.1 mg.kg-1/d for 3 weeks decreased GSH content in epididymides in rats. However, in vitro T4 at concentration of 10 micrograms/ml was found to exert no effect on the content of malondialdehyde in testis or H2O2 in testis and epididymis microsomes in rats.

Animals↗
PubMed1995

[A study on method of measurement and analysis of anterior chamber configuration by computerized image processing].

A new computerized method of measurement and analysis of the anterior chamber configuration in the human eye is described. The image or photograph of the anterior chamber taken with a slitlamp microscope is inputted into a computer with digitized camera or digitizer. After cornea, iris and lens surfaces are digitized, methematical corrections are made for the distortion from the slitlamp microscope and the refractive effect of cornea and aqueous humor to convert an optic distorted image into a true image. From the corrected image of anterior chamber, the data and parameter of anterior chamber configuration are measured and calculated. The reproducibility and accuracy of the method were 1.78% approximately 4.66% and 0.05 mm respectively and found to be adequate for clinical study of human eye under physiologic or disease state.

Anterior Chamber↗
PubMed1995

[Trabeculectomy combined with extracapsular cataract extraction and posterior chamber intraocular lens implantation].

PURPOSE: To evaluate the effect of trabeculectomy combined with extacapsular cataract extraction and posterior chamber intraocular lens implantation (triple surgeries) on the patients of coexisting cataract and glaucoma. METHODS: 18 cases (19 eyes) of coexisting cataract and glaucoma treated by the triple surgeries were reviewed. Mean follow-up was 14.7 months (rangs from 2 to 20 months). RESULTS: Intraocular pressure was controlled satisfyingly in all cases except one case required additional treatment of the anti-glaucoma drug. 78.9% of patients achieved 0.3 or better visual acuity. The operation complications consist of anterior uveitis and hyphaema. However, all of them were controlled within 14 days. CONCLUSION: The triple surgeries are safe and have definite effect on controlling the IOP and improving visual acuity.

Adult↗