PubMed Health⌕ Search

Biomedical subjects

P Wong

Publications and source records attributed to P Wong.

At least 19 recordsLinked to original sources
PubMed1992

Active cell death in hormone-dependent tissues.

Active cell death (ACD) in hormone-dependent tissues such as the prostate and mammary gland is readily induced by hormone ablation and by treatment with anti-androgens or anti-estrogens, calcium channel agonists and TGF beta. These agents induce a variety of genes within the hormone-dependent epithelial cells including TRPM-2, transglutaminase, poly(ADP-ribose) polymerase, Hsp27 and several other unidentified genes. Not all epithelial cells in the glands are equally sensitive to the induction of ACD. In the prostate, the secretory epithelial cells that are sensitive to hormone ablation are localized in the distal region of the prostatic ducts, and are in direct contact with the neighboring stroma. In contrast, the epithelial cells in the proximal regions of the ducts are more resistant to hormone ablation, probably because the permissive effects of the stroma are attenuated by the presence of the basal epithelial cells, which are intercalated between the epithelium and stroma. The underlying biology of ACD in prostate and mammary glands, and its relevance to hormone resistance, is discussed in this review.

Animals↗
PubMed1992

The pharmacological activity of nitroxyl: a potent vasodilator with activity similar to nitric oxide and/or endothelium-derived relaxing factor.

Chemical oxidation of N-hydroxy-L-arginine (NOHA) and other N-hydroxyguanidines has been previously shown to generate either nitric oxide (NO) or nitroxyl (HNO), depending on the oxidative conditions. Because N-hydroxy-L-arginine has been demonstrated to be a biosynthetic intermediate in the oxidative conversion of arginine to endothelium-derived relaxing factor, the possible formation of HNO through a biological process was considered. This study, therefore, explores the biological activity of HNO as a possible effector molecule, and the results indicate that HNO is capable of eliciting vasorelaxation in both rabbit aorta and bovine intrapulmonary artery by a guanylate cyclase-dependent pathway. The pharmacological properties of HNO were very similar to those of endothelium-derived relaxing factor, and the possible relationship between HNO and endothelium-derived relaxing factor is discussed.

Animals↗
PubMed1992

Cholesteryl ester storage disease: complex molecular effects of chronic lovastatin therapy.

To better characterize the in vivo effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibition on human lipid metabolism, an adolescent male with cholesteryl ester storage disease (CESD) was treated chronically with lovastatin. Therapy was associated with decreased liver-spleen size, improved but not normal serum lipids, a 26% decrease in hepatic cholesteryl ester, a 12% decrease in unesterified hepatic cholesterol, and a fourfold increase in hepatic low density lipoprotein (LDL) receptor protein. Hepatic mRNA levels for the LDL receptor and apolipoprotein (apo) B standardized to levels of hepatic gamma actin mRNA were unchanged with therapy. Kinetic studies revealed no change in the LDL fractional catabolic rate and a decrease in the LDL production rate. Size exclusion chromatography showed striking reductions in plasma very low density lipoprotein (VLDL) cholesterol and intermediate density lipoprotein (LDL) cholesterol but not LDL cholesterol with therapy. Mean LDL particle size and the LDL particle size range were increased by treatment. However, there was no difference in the ability of pretreatment or treatment LDL to bind to the LDL receptor on cultured cells consistent with previous studies in animals, indicating that lovastatin may alter LDL particles to impair interaction with the LDL receptor in vivo but not in vitro. Lovastatin therapy in CESD appears to be clinically beneficial and has complex effects on lipid metabolism that may include a dominant inhibitory effect on hepatic lipoprotein production, posttranscriptionally mediated induction of the LDL receptor, and alterations of LDL particles that interfere with their clearance by the LDL receptor in vivo.

Actins↗
PubMed1991

Person-to-person transmission of Brucella melitensis.

Human brucellosis is primarily an occupational hazard in the USA; in the Middle East and Africa ingestion of contaminated dairy products is an important route of infection. Whether human beings can become infected via person-to-person spread is uncertain. During an investigation of a commonsource, laboratory-associated outbreak due to Brucella melitensis, biotype 3, the wife of a microbiologist with serologically proven brucellosis became infected. Her blood isolate was indistinguishable from the epidemic strain. In the absence of other risk factors, we suggest that sexual intercourse is a possible means of transmission.

Brucella↗
PubMed1991

The prolactin-inducible protein (PIP/GCDFP-15) gene: cloning, structure and regulation.

The androgen and prolactin responsive prolactin-inducible protein (PIP)/gross cystic disease fluid protein (GCDFP-15) is expressed in benign and malignant human breast tumors and in such normal exocrine organs as sweat, salivary and lacrimal glands. In this paper we report the cloning and structure of the human gene, and describe potential mechanisms involved in its regulation by hormones. The entire PIP gene, 7 kb long, was found in a single recombinant phage clone. The gene has 4 exons ranging from 106 bp to 223 bp in length. Nuclear run-on experiments utilizing PIP genomic fragments to detect nascent PIP transcripts revealed that both androgen and prolactin increased transcription of the PIP gene. Neither hormone had any effect on the stability of PIP precursor RNA or mature mRNA. Therefore the PIP gene is an excellent model by which to study the molecular events associated with the actions of prolactin and androgen in the regulation of gene expression in mammalian cells.

Apolipoproteins↗
PubMed1991

Clinical investigations of halothane and isoflurane for induction and maintenance of foal anesthesia.

Fifty-eight foals were divided into two groups for study of aspects of the clinical anesthetic management of foals and to characterize effects of halothane (n = 30) and isoflurane (n = 28) in foals. There were no significant differences (P greater than 0.05) in the demographics of the two groups. Results of hemograms and biochemical analysis of venous blood samples before and after anesthesia were either not influenced or only mildly (clinically unimportant) affected by either agent. Like adult horses, foals have an increased PaCO2 when anesthetized with inhaled anesthetics. We could detect no difference in the magnitude of increase in PaCO2 with either anesthetic. Anesthetic induction and recovery was most rapid with isoflurane. The quality of induction and recovery was similarly acceptable with either agent. Heart rate during isoflurane was not significantly different from conscious conditions but during halothane, heart rate was significantly less than control except at 91-120 min when statistical significance was not detected. These results support the clinical impression that foals can be safely and reliably anesthetized with either agent.

Anesthesia, Inhalation↗
PubMed1990

Expression of HLA by the human trabecular meshwork and corneal endothelium.

By using immunohistochemical techniques, we demonstrated that HLA class I (A, B and C) and HLA class II (DR), the major histocompatibility antigens in man, are expressed constitutively by cells of the trabecular meshwork/Schlemm's canal system and corneal endothelium, as well as by the conjunctival epithelium, Langerhans cells, vascular endothelium and uvea. Because clinical studies indicate that these antigens are involved in mediating corneal graft rejection and possibly in glaucomatous disease of the eye, the presence of both class I and II HLA in the corneal endothelium and in the trabecular cells has important implications for an understanding of immune disorders in the anterior segment of the eye. The presence of HLA on trabecular cells raises the possibility that these antigens potentiate the recognized role of Langerhans cells at the limbus and that they participate in, and/or regulate, the maintenance and defense of the aqueous outflow pathway. Our findings also open up the possibility of using HLA as a genetic marker in the determination of susceptibility to these disorders in man.

Adult↗
PubMed1990

Carbamazepine metabolism in humans: effect of concurrent anticonvulsant therapy.

Free and total carbamazepine (CBZ) and carbamazepine-epoxide (CBZ-EP) plasma levels were obtained on 113 patients with epilepsy (18-61 years old) controlled on either monotherapy or coadministration with either phenobarbital (PB), phenytoin (PHT), valproic acid (VPA), or all three. A subset of patients were administered tetradeuterium labeled CBZ to evaluate the effects of autoinduction and coadministration of VPA on the kinetics of CBZ and its metabolite CBZ-EP. Polytherapy had variable effect on free and total CBZ plasma levels compared to monotherapy. Coadministered PHT (co-PHT), or all three anticonvulsants together (PHT, PB, and VPA: co-AEDs) decreased free and total CBZ plasma levels. No change was noted for coadministered VPA (co-VPA). Compared to monotherapy the free and total CBZ-EP levels increased with co-VPA, less with coadministered PB (co-PB), and no change with co-PHT or co-AEDs. Protein binding of CBZ and CBZ-EP was not affected by any antiepileptic drugs studied. The free and total CBZ-EP/CBZ ratio was tripled with co-VPA or co-AED's, and doubled with co-PHT or co-PB. Isotope labeling did not demonstrate any differences in half-life (t1/2), plasma clearance (Cl), or volume of distribution (Vd). Compared to naive controls, monotherapy and co-VPA decreased CBZ t1/2 by 50%, and more than doubled the CBZ Cl without a significant change in the Vd. Autoinduction is one explanation for these changes with chronic CBZ therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1989

Use of the polymerase chain reaction for the differential cross screening of libraries cloned into phage-lambda-based vectors.

We describe a simple and rapid method that can be used to identify sequences present in any two DNA libraries (either genomic or cDNA), provided only that the libraries are in different vectors with different cloning sites. This procedure makes use of the polymerase chain reaction (PCR) to amplify the inserts of one library. The product of the PCR reaction is then used to screen a second library to identify sequences which are common to both. We illustrate the use of this method for the systematic isolation of human X-chromosome-linked genomic clones that harbor sequences expressed in human chorioretinal tissue.

Animals↗
PubMed1979

Isolation of an abnormally phosphorylated erythrocyte membrane band 3 glycoprotein from patients with myotonic muscular dystrophy.

A fraction of erythrocyte Band 3 (Mr, 93,000) glycoprotein that demonstrates decreased autophosphorylation in membranes from myotonic muscular dystrophy patients is demonstrated. Sequential affinity chromatography of Triton X-100 solubilized erythrocyte membrane proteins separated three specifically retained glycoprotein fractions on a Ricin Communis I-Sepharose 4B column. One fraction contains a portion of the major sialoglycoprotein (apparent Mr, 78,000) and is specifically eluted from the column by 10 mM NaCl and 100 mM D-galactose (10/100). The two other glycoprotein fractions are eluted by 100 mM NaCl, 10 mM D-galactose (100/10) and 100 mM NaCl, 100 mM D-galactose (100/100). The composition of both fractions contains greater than 95% Band 3 (apparent Mr, 93,000 glycoprotein. The quantities of glycoprotein in each fraction obtained from erythrocytes of myotonic dystrophy patients did not differ from the quantities obtained from control erythrocytes. Following endogenous protein kinase incubations of ghosts with [gamma-32P]ATP, the specific [32P] phosphorylation of the 10/100 and 100/10 fractions are identical. The 100/100 fraction, which makes up approximately 3% of the total erythrocyte membrane protein, demonstrates a different pattern for myotonic dystrophy patients; specific phosphorylation was reduced by 50% relative to activity in control experiments. These findings are consistent with previous experiments that demonstrated decreased autophosphorylation of the glycoprotein portion of Band 3 (Roses & Appel, 1975, J. Membrane Biol 20:51) and are consistent with the autosomal dominant mode of inheritance in this disease.

Chromatography, Affinity↗
PubMed1979

Real-time high resolution ultrasound in the detection of biliary calculi.

A high-resolution real-time ultrasound sector scanner was used in the evaluation of patients with suspected gallbladder disease. This technique is noninvasive, requires minimal preparation, and takes less than five minutes for a thorough examination of the gallbladder and related anatomy. In 17 months, 959 patients were examined for suspected gallbladder disease and the gallbladder was adequately visualized in all but 5 patients. Follow-up information was obtained from surgery in 153 cases. There were 132 true-positive studies, 15 true-negative, 5 false-negative and one-false positive study. In a correlative study with oral cholecystography, calculi were detected ultrasonically in 5 cases that had been missed on the oral cholecystogram.

Cholecystography↗