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Biomedical subjects

J Pang

Publications and source records attributed to J Pang.

At least 19 recordsLinked to original sources
PubMed1992

Quantitation of human cellular retinoic acid-binding protein II (CRABP-II) RNA from cultured human skin fibroblast cells and human skin biopsies treated with retinoic acid.

A polymerase chain reaction (PCR) method has been validated for the quantitation of retinoic acid (RA) induction of cellular retinoic acid-binding protein II (CRABP-II) RNA from cultured human skin fibroblasts and human skin biopsies. The method utilizes reverse transcription and PCR (RT-PCR) to compare cellular CRABP-II RNA with a known amount of added internal standard RNA generated from a modified CRABP-II cDNA containing a 42 bp deletion. Thus, after RT-PCR of cellular and standard CRABP-II RNA in the same tube, the resulting DNA bands could be distinguished by size on ethidium bromide-stained, nondenaturing polyacrylamide gel. Serial dilutions of cellular RNA were co-amplified with a fixed amount of internal standard CRABP-II RNA, and the ratio of intensities of the two DNA bands was determined by computerized image analysis of the gel photograph. A linear relationship was found between the logs of this ratio and the input RNA. Absolute quantitation of cellular CRABP-II RNA was determined from the 'equivalence point', the dilution at which band intensities from cellular and standard RNAs were identical. Using this quantitative assay, the amount of CRABP-II RNA in cultured fibroblasts was 24 attomoles per microgram total RNA. A 4.2-fold increase in CRABP-II RNA was seen following 24 hours treatment with 10(-6) M RA. CRABP-II RNA content in skin biopsies taken from 3 human subjects ranged from 16 to 25 attomole/micrograms RNA. Topical treatment with 0.1% RA cream resulted in induction ranging from 3.9- to 12-fold over vehicle treatment. The method described here offers a rapid, sensitive and quantitative assay of specific RNAs, and should be especially useful for the measurement of RNA levels from small solid-tissue biopsies.

Base Sequence↗
PubMed1992

Superoxide generation by the human polymorphonuclear leukocyte in response to latex beads.

In this study, superoxide formation was not immediately detected when polymorphonuclear leukocytes were treated with linoleyl alcohol-coated, carboxy-modified latex beads. However, all other measures of neutrophil activation were present. Superoxide was not detected until 30 min after the initial exposure to beads. However, an O2(-)-producing, NADPH-dependent oxidase is active 15 min after exposure. When polymorphonuclear leukocytes are pretreated with cytochalasin B, superoxide production is detected immediately after exposure to the beads. Superoxide secretion after treatment with linoleyl alcohol-coated latex beads is compared with the response to other latex beads. The results imply that neutrophils form a phagolysosome around linoleyl alcohol-coated latex beads that is tightly sealed and does not allow superoxide to escape into the medium where it could be detected by the reduction of ferricytochrome c.

Cells, Cultured↗
PubMed1992

Use of modified nucleotides and uracil-DNA glycosylase (UNG) for the control of contamination in the PCR-based amplification of RNA.

The inadvertent carryover of amplified fragments of nucleic acids (amplicons) is a potential source of contamination in the polymerase chain reaction. Recently, a method has been developed to generate amplicons with deoxyuracil triphosphate (dUTP) and to specifically hydrolyze these amplicons with uracil-DNA glycosylase (UNG) following the completion of the assay. We evaluated this system for the specific amplification of RNA from coxsackievirus A3 and B3. We found that RNA from both viruses could be amplified with dUTP, although the use of this triphosphate in place of TTP resulted in some loss of assay sensitivity. We also found that the dUTP-containing amplicons could be efficiently hydrolyzed by UNG, resulting in a 10,000,000-fold reduction in amplicon concentration with little effect on the native nucleic acid. The dUTP-UNG method has a great deal of potential for reducing amplicon contamination during the routine performance of nucleic acid amplification reactions.

Artifacts↗
PubMed1992

Do "right-armed" lefthanders have different lateralization of motor control for the proximal and distal musculature?

Geschwind and Galaburda (1985) have suggested that specialization for the control of distal and proximal musculature might be located in different hemispheres in some individuals. Because inconsistent lefthanders (as defined by Ponton, 1987; Peters and Servos, 1989) tend to write with the left hand but throw with the right arm, and have a stronger right arm (Peters, 1990), it was thought that individuals in this group might provide evidence for the prediction made by Geschwind and Galaburda. This did not prove to be the case for tapping speed, where righthanders, inconsistent and consistent lefthanders all showed congruence. It appears that the question "are some left-handers right-armed?" can be answered only relative to specific activities.

Adult↗
PubMed1992

Hypomethylation of beta-hydroxy-beta-methyl-glutaryl coenzyme A reductase gene and its expression during hepatocarcinogenesis in the rat.

Our earlier studies had demonstrated that inhibition of DNA methylation following carcinogen treatment potentiated initiation of the carcinogenic process in the rat liver system. The hepatic nodules developed by initiation-promotion protocols showed a characteristic hypomethylation in the cell-cycle-related genes c-fos, c-myc and c-Ha-ras. In the present study we have found that the gene for beta-hydroxy-beta-methyl glutaryl coenzyme A reductase, a major rate-limiting enzyme in the biogenesis of mevalonate, is also hypomethylated at both CCGG and GCGC sites and expressed in hepatic nodules. This gene, however, did not exhibit hypomethylation in CCGG sequences in non-nodular surrounding liver, livers from rats subjected to two-thirds partial hepatectomy, or exposed to initiator alone (1,2-dimethylhydrazine given 18 h after partial hepatectomy) or to diets containing 1% orotic acid alone (promoting regimen). The activity of the enzyme and mevalonate formation are positively correlated with DNA synthesis and cell proliferation--two key components of the carcinogenic process. Taken together, the results suggest that hypomethylation of specific genes occurs in the carcinogenic process and this altered pattern of DNA methylation may play a role in the growth of the nodules.

1,2-Dimethylhydrazine↗
PubMed1992

A prospective study of community-acquired pneumonia in Hong Kong.

A prospective study of community-acquired pneumonia in Hong Kong was carried out between January and December, 1988. Ninety adults (57 male) with a mean age of 57.3 years were admitted to the Prince of Wales Hospital with community-acquired pneumonia. The etiologic diagnosis of pneumonia was made in 37 cases (41 percent). Pneumococcal infection was diagnosed in 11 patients (12 percent). The same number of patients had pulmonary tuberculosis presenting as acute pneumonia. It could not be differentiated from other causes of pneumonia on clinical and radiologic grounds, although pleural effusion and upper lobe involvement were more common in patients with tuberculosis. Chlamydia species were identified in five patients (6 percent) and Mycoplasma pneumoniae was identified in three patients (3 percent). There was no case of Legionnaires' disease. The etiologic agent could not be identified in 59 percent of cases. The low incidence of etiologic diagnosis of community-acquired pneumonia was probably related to the widespread use of antibiotics in private practice. Tuberculosis is an important cause of community-acquired pneumonia in Hong Kong and this diagnosis should be considered in patients who fail to respond to first-line antibiotics.

Adult↗
PubMed1992

Localization of human immunodeficiency virus core antigen in term human placentas.

Evidence of human immunodeficiency virus (HIV) replication was sought in human placentas obtained at term from pregnancies complicated by maternal HIV infection. Placentas were obtained from the pregnancies of 19 HIV-seropositive women, 4 women who were seronegative, and 4 untested women with no risk factors for HIV infection. These placentas were each examined by immunoperoxidase immunocytochemistry using monoclonal anti-p24/55 antibodies. In addition, minced placental tissue from 11 of the seropositive pregnancies and the 3 seronegative pregnancies were co-cultivated with stimulated human peripheral blood mononuclear cells. The clinical status of the infants born to the HIV-seropositive women was assessed when the infants were 8 to 28 months of age. P24/55 antigen was detected in 5 of the 19 placentas of the HIV-seropositive pregnancies and in none of the 8 placentas of seronegative or low-risk pregnancies. This HIV core viral antigen was located exclusively in the cytoplasm of villous cells with morphological characteristics of macrophages. The HIV antigen-containing cells were very sparsely distributed. Staining of the trophoblast was not observed in any placental specimen. Human immunodeficiency virus was isolated in culture from 3 of the 11 placentas from seropositive pregnancies. Clinical follow-up has not revealed a relationship between infection of the infant and either p24/55 antigen identification or isolation of virus from the placenta. Virological and histological evidence of HIV replication is found in approximately one fourth of placentas obtained at term from pregnancies complicated by maternal HIV infection. Replicating virus appears localized to sparse macrophages located within the chorionic villi, but specifically not within the trophoblastic layer.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1990

Solitary fibrous tumor of pleura: expression of cytokeratins.

A case of solitary fibrous tumor of the pleura (SFT) is presented. The histogenesis of this uncommon tumor is debated with most investigators favouring origin in submesothelial fibroblasts. Part of the evidence supporting this has been the persistent negativity of the tumor cells for cytokeratin--a feature militating against origin in mesothelial-lining cells. Our case shows unequivocal focal cytokeratin positivity in tumor cells; we feel that although this indicates mesothelial differentiation it does not militate against origin in submesothelial fibroblasts since, in reactive conditions, these are capable of mesothelial differentiation including expression of cytokeratin. Indeed, it reinforces the hypothesis that SFT is of submesothelial origin. Solitary fibrous tumors can be cellular and atypical. The reactivity of the tumor with cytokeratin, albeit rarely, should be considered in differentiating SFT from sarcomatoid mesothelioma.

Aged↗
PubMed1989

Isolated giant tuberculomata of the liver detected by computed tomography.

Isolated giant tuberculomata of the liver are rare, and they are frequently misdiagnosed as primary or secondary tumors of the liver. We describe the computed tomography findings in 2 patients with giant tuberculomata of the liver. One patient had a large low-attenuation lesion with rim enhancement after contrast. The other patient had multiple calcific lesions that did not enhance but showed a rim of hypoattenuation after contrast. Biopsy established the diagnosis and both patients recovered with antituberculous chemotherapy.

Adult↗
PubMed1989

Prevalence of asthma, atopy, and bronchial hyperreactivity in bronchiectasis: a controlled study.

The prevalence of atopic diseases and bronchial reactivity to histamine and methacholine was determined in 36 patients with bronchiectasis and in 36 control patients matched for age, sex, and smoking history. There was no difference in the prevalence of asthma, other atopic diseases, family history of atopic diseases, or positive responses to skinprick tests (nine versus five) in the two groups. The prevalence of bronchial hyperreactivity, however, was significantly higher in the group with bronchiectasis than in the control group for both histamine (7 v 0 patients) and methacholine (6 v 0 patients). The group with bronchiectasis had more airflow obstruction (mean FEV1 67% predicted), but there was no correlation between spirometric indices and log PD20 (the log dose of histamine or methacholine causing a 20% fall in FEV1). This suggests that, although reduced airway calibre may be a factor underlying bronchial hyperreactivity in bronchiectasis, it is not the only mechanism. Further studies are needed to determine whether bronchial hyperreactivity has a causative role in the pathogenesis of bronchiectasis or whether it occurs as a result of the disease.

Adult↗
PubMed1989

Diffusing capacity in healthy elderly Chinese.

Diffusing capacity (DLCO) was measured in 260 healthy subjects aged 60-86 years who were leading an active life in the community. DLCO correlated with body surface area and spirometric indices, and declined with age. It was lower in women, in smokers and in those with chronic bronchitis. Multiple regression equations based on age and body surface area were derived for elderly Chinese men and women. Compared with predicted values based on studies of Caucasians of all ages, those for elderly Chinese men were higher, while those for elderly women were similar. Predicted values for an elderly Chinese population should be derived from equations established from this survey rather than those extrapolated from Caucasians of all ages. DLCO/VA correlated with weight and body surface area but not with height, and declined with age. There was no difference between men and women, and between those with or without symptoms of chronic bronchitis. Predicted values from this study of elderly Chinese were comparable to those derived from Caucasians of all ages. Differences in DLCO values for elderly Chinese compared to Caucasians may be explained by differences in lung volumes rather than ethnic variations in the diffusing characteristics of the alveolar capillary membrane, and by the small numbers of elderly subjects in some of the studies of Caucasian subjects.

Age Factors↗
PubMed1989

Therapeutic embolization of pulmonary arteriovenous malformation.

A 49-year old man presented with recurrent transient ischaemic attacks and a pulmonary arteriovenous malformation (PAM) was found in his lower left lobe. Left lower lobectomy was performed, and the attacks ceased. However, 18 months later, a fresh PAM was detected in the right lower lobe. In order to avoid further lung resection, therapeutic embolization with metal-dacron coils and gelfoam was performed, resulting in complete occlusion of the PAM. The patient remained well at follow-up 6 months later. Therapeutic embolization is an effective alternative to surgery in the treatment of PAM, especially in the presence of multiple lesions when it is important to conserve functional lung tissue.

Arteriovenous Malformations↗
PubMed1988

Metastasizing leiomyoma of the uterus.

This report describes a patient who underwent a subtotal hysterectomy 6 years ago for fibroids. She re-presented recently with lung metastases and a pelvic mass. Macroscopic appearances at laparotomy suggested a leiomyosarcoma of the uterine stump, but histological appearances suggested the patient was suffering from the rare condition 'metastasizing leiomyoma'. Subsequent response to hormone manipulation supported the latter diagnosis.

Adult↗
PubMed1988

Spirometry in healthy elderly Chinese.

Forced expiratory volume (FEV1), forced vital capacity (FVC), and peak expiratory flow (PEF) were measured in healthy subjects (129 men, 210 women) aged 60 years and above who were leading an independent and active life in the community. Women but not men showed an age related decline in FEV1 and FVC. Correlations of FEV1 and FVC with height were weaker than those reported for all age groups. Male ex-smokers had lower FEV1 values than current smokers and non-smokers. Regression equations are derived for men and women for predicting values appropriate to Chinese elderly people. These values are slightly lower than those for white people, but the difference is not as great as in values derived from surveys of all age groups.

Aged↗