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Biomedical subjects

N Wang

Publications and source records attributed to N Wang.

At least 289 records · Page 16Linked to original sources
PubMed1996

The immune response to class I-associated tumor-specific cutaneous T-cell lymphoma antigens.

In order to determine whether the neoplastic T cells from patients with cutaneous T-cell lymphoma express tumor-specific antigens that can serve as the targets of an immune response, we took advantage of family-specific monoclonal antibodies, magnetic bead technology, and recombinant cytokines, which provided the previously precluded ability to isolate and expand populations of purified tumor and autologous CD8 cytotoxic T cells. Four patients with advanced cutaneous T-cell lymphoma had CD8 cells that specifically killed autologous tumor in a class I limited fashion. Tumor cell cytolysis could be specifically enhanced by pre-culture with autologous gamma-irradiated tumor. The cytolytic T cells produced tumor necrosis factor-alpha in response to stimulation with autologous tumor. The presence of tumor-specific cytotoxic T cells recognizing distinctive class I associated molecules on cutaneous T-cell lymphoma tumor cells suggests that infiltration of early lesions by CD8 cells reflects host immunity to the neoplasm. These studies provide the foundation for the development of tumor vaccines through the use of cytotoxic T cells to isolate and characterize tumor-associated cutaneous T-cell lymphoma peptides.

Antibody Formation↗
PubMed1996

Ultraviolet radiation B induces differentiation and protein kinase C in normal human epidermal keratinocytes.

Mid-wave ultraviolet radiation (UVB, 280-320 nm) is highly efficient at inducing erythema, pyrimidine dimers in DNA, oncogene expression and initiation of cutaneous tumors. These UVB-induced responses of epidermal cells have been correlated with the direct effects of UVB on DNA. However, UVB has also been shown to have biologic effects at the cellular level that appear to mimic some of the membrane-associated effects produced by phorbol ester tumor promoters such as 12-O-tetradecanoyl phorbol-13-acetate (TPA). For example, we have previously shown that both UVB irradiation and TPA treatment are followed by release of arachidonic acid and a rapid, dose-dependent inhibition of epidermal growth factor (EGF) binding. TPA generates cellular responses through activation of a phospholipid-dependent, calcium-sensitive protein kinase, protein kinase C (PKC). The primary goal of the studies described here was to compare the cellular effects of TPA with those of UVB with special regard to PKC and keratinocyte growth control, using normal human epidermal keratinocytes. The results obtained showed that both TPA and UVB radiation induced differentiation in normal human keratinocytes. UVB radiation, however, increased both cytosolic and membrane-associated levels of PKC, in contrast to TPA, which increased PKC primarily in the membrane fraction. PKC is probably not the initial chromophore or target molecule of UVB, but because activation of PKC has been shown to be essential for keratinocyte differentiation, differentiation induced by UVB may be caused by activation of PKC by UVB-induced release of diacylglycerol or arachidonic acid.

Carcinogens↗
PubMed1996

Genetic characterization of human immunodeficiency virus type 1 in blood and genital secretions: evidence for viral compartmentalization and selection during sexual transmission.

To explore the mechanism of sexual transmission of human immunodeficiency virus type 1 (HIV-1), we compared HIV-1 gp120 sequences in longitudinal samples from five acute seroconvertors with those from their corresponding sexual partners (transmitters). We used a quantitative homoduplex tracking assay to compare the overall genetic composition of HIV-1 quasispecies in each transmission pair and to track the transmitted viruses during the acute and asymptomatic stages of HIV-1 infection. In the chronically infected transmitters, HIV-1 variants in genital secretions differed from those in blood and variants in cells differed from those in cell-free plasma, indicating remarkable sequence heterogeneity in these subjects as well as compartmentalization of the virus in different bodily sites. Conversely, two of five seroconvertors had only a few related variants and three of five harbored only one viral population, indicating that in these subjects the transmitted viruses were typically homogeneous. Transmitted viruses were evident in the donor's seminal plasma (one of five cases) and even more so in their seminal cells (three of five cases), suggesting that both cell-associated and cell-free viruses can be transmitted. In every pair studied, the transmitted variant(s) represents only a minor population in the semen of the corresponding transmitter, thereby providing evidence that HIV-1 selection indeed occurs during sexual transmission.

Amino Acid Sequence↗
PubMed1996

Pharmacological activation changes stiffness of cultured human airway smooth muscle cells.

Using magnetic twisting cytometry (MTC), we measured the cytoskeletal stiffness of adherent human airway smooth muscle (HASM) cells. We hypothesized that modulation of actin-myosin interactions by application of contractile agonists would induce changes in cytoskeletal stiffness. In cells plated on high-density collagen, bradykinin (10(-6) M) and histamine (10(-4) M) increased stiffness by 85 +/- 15 and 68 +/- 16%, respectively. Increases in cell stiffness were also consistently observed after acetylcholine, substance P, and KCl. The bronchodilator agonists isoproterenol, prostaglandin E2, forskolin, dibutryl adenosine 3', 5'-cyclic monophosphate, and 8-bromoguanosine 3', 5'-cyclic monophosphate each caused a dose-dependent decrease in cell stiffness in unstimulated as well as bradykinin-treated cells. HASM cells plated on high-density collagen were stiffer than cells plated on low-density collagen (126 +/- 16 vs. 43 +/- 3 dyn/cm2) and developed more pronounced increases in stiffness in response to bradykinin as well as more pronounced decreases in stiffness in response to isoproterenol. These results are consistent with the hypothesis that modulation of actin-myosin interactions by application of contractile agonists causes changes in cytoskeletal stiffness of HASM cells. MTC may be a valuable tool for evaluating the mechanisms of pharmacomechanical coupling in airway smooth muscle cells in culture.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1996

A case of herpetiform pemphigus associated with autoimmune hemolytic anemia: detection of autoantibodies against multiple epidermal antigens.

We report a case who was clinically and histopathologically diagnosed as herpetiform pemphigus (HP) and associated with autoimmune hemolytic anemia (AIHA). However, immunofluorescence studies demonstrated concurrent anti-cell-surface and anti-basement-membrane-zone antibodies in the patient's serum. Immunochemical studies showed that the patient's serum reacted with both the pemphigus foliaceus antigen and the two bullous pemphigoid antigens. Subsequently, the patient developed AIHA. Both anemia and skin lesions were successfully treated with oral prednisolone. We believe that this is the first case with HP in association with AIHA. The presence of autoantibodies against multiple antigens suggests an abnormal immunologic tolerance in the antibody production system in this patient.

Anemia, Hemolytic, Autoimmune↗
PubMed1996

[The application of Ultrasound Biomicroscope in anterior segment contusion].

PURPOSE: To study the clinical value of Ultrasound Biomicroscope in anterior segment contusion. METHODS: Seven eyes with anterior segment contusion were examined by regular ophthalmic examination, ophthalmic B-scan, and Ultrasound Biomicroscope. RESULTS: Ultrasound Biomicroscope can show angle recession, cyclodialysis, iridodialysis, zonular breaking, lens dislocation and vitreous protrusion to posterior chamber. In most cases cyclodialysis and shallow detachment of choroid can not be diagnosed because shallow anterior chamber and hypton. CONCLUSION: The result suggests that Ultrasound Biomicroscope has high clinical value in diagnosis of anterior segment contusion, especially in cornea edema, hyphemia, hypton, Ultrasound Biomicroscope can refer precise diagnosis of anterior segment contusion.

Adult↗
PubMed1996

Quasilikelihood estimation in measurement error models with correlated replicates.

We consider quasilikelihood models when some of the predictors are measured with error. In many cases, the true but fallible predictor is impossible to measure, and the best one can do is to obtain replicates of the fallible predictor. We consider the case that the replicates are not independent. If one assumes that replicates are independent and they are not, one typically underestimates the extent of the measurement error, leading to an inconsistent errors in variables correction. We devise techniques for estimating the measurement error covariance matrix. In addition, we discuss how one might perform a quasilikelihood analysis by computing the mean and variance functions of the observed data, both using approximations and also exactly through a Monte Carlo method. The methods are illustrated on a data set involving systolic blood pressure and urinary sodium chloride, where the measurement errors appear to be approximately normally distributed but highly correlated, and the distribution of the true predictor is reasonably modeled as a mixture of normals.

Analysis of Variance↗
PubMed1996

Experimental nonpenetrating transscleral cyclodiathermy in rabbits.

BACKGROUND AND OBJECTIVE: Acute and long-term effects of contact transscleral cyclodiathermy (CTCD) were studied in rabbits. MATERIALS AND METHODS: In the acute phase, three evenly spaced applications were placed at the limbus in each of four quadrants using the Ophthalmic Diathermy TR4000 (MIRA, Inc., Waltham, MA). Each quadrant of 17 eyes of 13 Dutchbelted rabbits was treated with radio frequencies (RFs) of 1.0 to 4.5, for times of 0.5, 0.75, 1.0 to 3.0, and 4.0 to 10.0 seconds. Eyes were then immediately enucleated and fixed in Karnovsky's solution after the rabbits had been sacrificed with 3 ml of pentobarbital sodium. In the longitudinal phase, four groups of six rabbits each were treated with 20 evenly spaced applications at the limbus at one of four settings: 1.5 RFs/4 seconds, 2.0 RFs/3 seconds, 2.5 RFs/2 seconds, or 3.0 RFs/2 seconds. Intraocular pressures were measured on alternate days for 1 week prior to treatment and for 4 weeks after treatment, following which the eyes were enucleated and fixed in Karnovsky's solution. RESULTS: Gross examination of the acute phase eyes revealed blanching of the ciliary processes at RF settings of 2.5 and higher with exposure times of 1.5 seconds or longer. Gross and light microscopic studies showed that levels of destruction correlated positively with RF settings and exposure times. Higher RF levels resulted in scleral coagulation necrosis on light microscopy. In addition, there was coagulation necrosis of the pigmented and nonpigmented ciliary epithelium and stroma. Longitudinal phase study showed a significant decrease in intraocular pressure (IOP) in the four groups of rabbits treated over the 4-week follow-up period (P = .005, multivariate analysis of variance [MANOVA]). Rabbits treated at higher RF levels sustained a greater IOP-lowering effect (P = .025, MANOVA). Gross and light microscopic examination revealed focal atrophy, fusion, and fibrosis of the ciliary processes. CONCLUSION: Nonpenetrating CTCD results in focal destruction of the ciliary body in rabbits. The authors found that significant reduction in IOP was possible over the 4-week follow-up period in the Dutch-belted rabbits treated, with greater IOP and tissue effects at higher RF settings.

Acute-Phase Reaction↗
PubMed1996

[Effect of L-TYR on the uterine cytosol estradiol and progesterone receptors in rat].

The effect of L-TYR on rat uterine cytosol estradiol and progesterone receptor contents was studied. The rats were divided into 4 groups: proestrus, estrus, metestrus and diestrus. One horn of each uterus was injected with L-TYR (2 mmol/L, 0.1 ml), while the other with 0.1 ml 0.9% NaCl serving as control. The mole concentration of receptor was calculated with RRA and cytosol receptor content was expressed as fmol/mg protein. It was shown that L-TYR decreased significantly the uterine estradiol and progesterone receptors in proestrus, estrus and diestrus phases of the estrus cycle, but without effect on metestrus. This was most probably due to competitive combination of TYR with some functional groups of the estradiol receptor because of similar chemical conformation of TYR to estradiol. Threonine could also decrease, to some extent, the uterine cytosol progesterone receptor content at estrus and dioestrus phases. Serine had no effect on the contents of uterine cytosol either estradiol or progesterone receptor in normal and ovariectomized rats. The present observation indicates that L-TYR appears to affect the synthesis of the cytosol estradiol and progesterone receptor in the rat uterus independent, however, of endogenous ovarian sex hormones, since the effect is still present in the ovariectomized animals.

Animals↗
PubMed1996

Characterization of a peptide antibody against a C-terminal part of human and mouse cytosolic thymidine kinase, which is a marker for cell proliferation.

An affinity-purified anti-TK1 antibody (pAb1) raised against a synthetic peptide (amino acids K211PGEAVAARKLFAPQ225) corresponding to part of the C-terminus of human cytosolic thymidine kinase (TK1) was produced and characterized by enzyme-linked immunosorbent assay, Western immunoblotting and immunoprecipitation as well as by immunostaining of intact cells. pAb1 recognized a single 25 kDa TK1 polypeptide in extracts of human and rodent cells. The protein was localized to the cytoplasm, as studied by immunohistochemistry and there was no staining in G1/G0 cells or mutant cells lacking TK1 activity, while it was high in S-phase and G2 cells. When series of peptides were tested for antibody binding in which alanine was replacing each of the other amino acids one by one, lysines 211 and 220, proline 212 and glutamic acid 214 were found to be important for antibody reactivity. These results indicate that amino acids 211-214, which may form a turn region, constitute a major recognition site for pAb1, and this structure may also be involved in the cell cycle-dependent modification of TK1, pAb1 is a very useful tool for studies of the cell cycle regulation of TK1, and it may be used to identify and quantify rapidly proliferating cells such as tumor cells.

Amino Acid Sequence↗
PubMed1996

Exercise training in black adolescents: changes in blood lipids and Vo2max.

The purpose of this investigation was to evaluate the effects of a 15-week exercise training program on cardiovascular and blood lipid variables in black adolescents. Subjects consisted of black males with 12 of these participating in an exercise conditioning program and 5 designated as the control group participating in a team sports program. The mean +/- SD age was 12.8 +/- 0.97 yrs. Training for the exercise group was conducted 5 d.wk-1 for 15 weeks (weight training 2 d.wk-1 and aerobic training 3 d.wk-1). The following mean +/- SD significant changes were found for pre- to post-training for the exercise group (P < 0.05) with no significant change for controls: high density lipoprotein cholesterol (HDL-C) 1.11 +/- 0.18 to 1.28 +/- 0.17 (mmol.l-1), low density lipoprotein cholesterol (LDL-C) 2.73 +/- 0.74 to 2.41 +/- 0.81 (mmol.l-1), maximal oxygen uptake (VO2max) 43.7 +/- 9.4 to 48.2 +/- 9.7 (ml.kg-1.min-1), and maximal ventilation (VE max) 70.59 +/- 16.8 to 80.93 +/- 14.6 (L.min-1). In addition, no significant changes were found for blood pressure or other blood lipid parameters for either group. Results of this study show that exercise training can favorably alter blood lipid and VO2max values. Therefore, a vigorous exercise training program for young black males can favorably affect their cardiovascular risk profile.

Adolescent↗
PubMed1996

[Pharmacokinetics of naltrexone hydrochloride and naltrexone glucuronide in the dog].

Pharmacokinetics of naltrexone hydrochloride (NTX) and naltrexone glucuronide was studied in the dog using HPLC-electrochemical detection with naloxone as internal standard. After iv 5 mg or po 10 mg NTX, the plasma concentration-time curves of NTX were found to fit to a two-compartment model and a single compartment with first-order absorption. The elimination half-lives of NTX were 78 +/- 6 min and 74 +/- 6 min, respectively. Although NTX could be absorbed rapidly in the dog after po administration, the plasma concentration of the parent drug was very low and its absolute bioavailability was 15.8%. The experiments showed that the major metabolite of NTX in dog plasma was beta-glucuronidase-hydrolyzable conjugate. Dosing NTX intravenously and orally, the plasma levels of the conjugate were 1.3 and 23 times as high as that of the parent drug, the elimination half-lives of the glucuronide from plasma were 3.4 h and 12.6 h, respectively. The results indicate that NTX is subjected to a marked first-pass effect in the dog after oral administration.

Administration, Oral↗
PubMed1996

[Gene diagnosis for hepatolenticular degeneration by genetic linkage analysis with four short tandem repeat polymorphisms].

OBJECTIVE: To study the clinical application value of genetic linkage analysis for hepatolenticular degenaration (Wilson's disease, WD) with four STR--D13S316, D13S133, D13S301, and D13S314. METHODS: Polymorphisms of the four short STR, of which one (D13S301) was located in WD gene and the other three (D13S316, D13S133 and D13S314) were at flanking sites of the gene, were amplified by polymerase chain reaction, and the alleles indentification was performed with denaturing polyacrylamide gel electrophoresis and used as genetic marker for haplotype analysis. RESULTS: Genetic linkage analysis indicated that among 56 individuals (35 siblings and 21 secondary-relatives) without any clinical symptoms, 26 were WD heterozygotes, 2 presymptomatic and 28 normal. Among three patient previously diagnosed as possible WD patients, one was identified as WD heterozygote and the other two WD patients definitely. CONCLUSION: This genetic diagnosis system based on the four STR polymorphisms is of high clinical application value for distinguishing individuals from WD families.

Adolescent↗
PubMed1996

Chemosensitizing effect of verapamil on Swiss-3T3 cells transfected with human MDR1 gene.

To further understand the characteristics of drug resistance reversal of verapamil, the relationship between the level of doxorubicin resistance and the magnitude of modulation by verapamil was examined in multidrug resistant Swiss-3T3 cells transfected with human MDR1 gene. In independently isolated transfectants doxorubicin cytotoxicity decreased markedly compared with parent cells. Potentiation of doxorubicin toxicity by a noncytotoxic concentration of 3 mumol.L-1 of verapamil was much greater in transfectants than in parent cells, while the magnitude of reversal was inversely dependent on the level of resistance. Southern blot hybridization indicated the MDR1 cDNA integration in genomics of each transfectant. Defect in cellular accumulation of doxorubicin was restored by verapamil in transfected cells. The saturation of active drug transport that may involve the magnitude changes of potentiation by verapamil, and the mode of interaction between P-glycoprotein and drugs, were discussed.

3T3 Cells↗
PubMed1996

Clinical and experimental studies on the treatment of senile constipation with shenshen wan.

From August 1988 through February 1991, we have successfully treated 400 cases of senile constipation with self-made Shenshen Wan with a total effective rate of 98%. A group of patients taking Maren Wan served as controls. Clinical practice has proved that Shenshen Wan can not only relax the bowels, but also improve renal function. Furthermore, no side effects whatever were observed after a prolonged administration of the pills.

Aged↗
PubMed1996

Doxorubicin cellular pharmacokinetics plays no role in chemosensitizing effect of verapamil on Swiss-3T3 cells.

AIM: To find whether or not the doxorubicin (Dox) cellular pharmacokinetics plays a role in chemosensitizing effect of verapamil (Ver) on drug sensitive cells. METHODS: Cytotoxicity and cellular Dox contents (during accumulation and retention periods) were measured in the absence and presence of verapamil in Swiss-3T3 cells and compared with those in multidrug resistant (MDR) MCF-7Adr cells and drug sensitive MCF-7WT cells. mdr-1 mRNA expression in Swiss-3T3 cells was analyzed. RESULT: Dox cytotoxicity was enhanced 2.0-fold in Swiss-3T3 cells by Ver (3 mumol.L-1) and 3.6-fold in MCF-7Adr cells by Ver (6 mumol.L-1), but not in MCF-7WT cells (Ver 6 mumol.L-1). Cellular accumulation of equi-effective concentrations of Dox increased at 6-h incubation in the presence of Ver in Swiss-3T3 (1.5-fold)i and MCF-7WT cells (2.1-fold) but decreased rapidly in MCF-7Adr cells by 20% to 50% compared to that in the absence of Ver. Cellular retention of Dox decreased after 10-min increase in the presence of Ver in Swiss-3T3 cells compared to that in the absence of Ver, that was similar to that in MCF-7WT cells, while the retention was augmented by Ver in MCF-7Adr cells. Slot blot analysis of RNA revealed no mdr-1 gene expression in Swiss-3T3 cells. CONCLUSION: Changes in cellular accumulation and retention of Dox did not account for the chemosensitizing effect of Ver on Swiss-3T3 cells.

3T3 Cells↗
PubMed1995

Fluorescence image cytometry for measurement of nuclear DNA content in surgical pathology.

A study was made on various methodological aspects of fluorescence image cytometry (FICM) for measurement of nuclear DNA content by using CCD cameras attached to an epifluorescence microscope. Cell nuclei of paraffin-embedded specimens from mouse tissues and human prostate carcinomas were isolated and stained with 4'-6-diamidino-2-phenylindole (DAPI). We found that fluorescence fading, lamp stability, and the homogeneity of the illumination can easily be controlled. A camera with a signal-to-noise ratio of 53 dB gave a slightly more precise measurement than did a 46-dB camera. The linearity of the analysis results was very good. The coefficient of variation of mouse kidney standard cells in the DNA histograms was about 5% and 7.4% in histograms of prostate carcinoma biopsies. Stained cell nuclei can be stored for long periods at -20 degrees C without impairment of quality. Comparative measurements of ploidy by FICM and flow cytometry confirmed the accuracy of the FICM analyses. Thus, FICM appears to be an easy method for quantifying the DNA content of visually inspected cell nuclei in surgical pathology.

Animals↗