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Biomedical subjects

P Chow

Publications and source records attributed to P Chow.

At least 19 recordsLinked to original sources
PubMed2000

Respiratory monitoring using an air-mattress system.

This paper describes a non-invasive respiratory monitoring system using an air mattress. The air-mattress system features multiple air compartments to monitor movements of the thorax and the abdomen separately. To evaluate the performance of the air-mattress system, four subjects were selected for the study and their separate ribcage and abdominal movements were monitored simultaneously by respiratory inductive phlethysmography belts and the air-mattress system. The sensitivity and accuracy indices of the air-mattress system for the detection of hypopnoeas scored remarkably well (above 90%). In addition, it was noted that the mean error in the measurement of the respiratory rate between the two systems was very small. This paper shows that the air-mattress system can be a reliable non-invasive respiratory monitoring system to detect simple abnormalities in breathing, such as respiration rate and hypopnoeas.

Abdomen↗
PubMed2000

Preliminary development of the Body Image Affect Scale.

A new body-image questionnaire was developed to measure the affect associated with a negative body image. Responses showed a Cronbach coefficient alpha of .84 and a negative correlation of -.21 with using humor in times of stress.

Adult↗
PubMed2000

Expertise sensitive item selection.

In this paper we describe and illustrate a procedure for selecting items from a large pool for a certification test. The proposed procedure, which is intended to improve the alignment of the certification test with on-the-job performance, is based on an expertise sensitive index. This index for an item is the difference between the item's p values for experts and novices. An example is provided of the application of the index for selecting items to be used in certifying bakers.

Canada↗
PubMed1998

A comparative study on the efficacy of CD8-positive cells in enhancing allogeneic bone marrow engraftment: cell sorting vs microbead selection.

We have used a superparamagnetic microbead selection system to positively select a murine bone marrow CD8+ cell population. The functional ability of these cells to enhance allogeneic bone marrow engraftment was compared with that of fluorescence activated cell sorter purified CD8+ cells. The CD8+ cell population prepared by the microbead selection procedure was as effective as cell sorter purified CD8+ cells in enhancing T cell-depleted allogeneic bone marrow engraftment in lethally irradiated mice. Phenotypic characterization of these cells shows that most of these CD8+ cells express CD3 and the T cell antigen receptor complex.

Animals↗
PubMed1996

Normal subjects consuming physiological levels of 18:3(n-3) and 20:5(n-3) from flaxseed or fish oils have characteristic differences in plasma lipid and lipoprotein fatty acid levels.

The study assessed the effect of low doses of fatty acids from fish or flaxseed oil on plasma lipid concentrations in normal humans consuming diets with either high (0.87, n = 11) or low (0.48, n = 15) dietary polyunsaturated/saturated fatty acid (P/S) ratios. The dose of (n-3) fatty acids reflected an (n-3) intake that could easily be attained by selection of foods in a normal diet. The individuals were initially supplemented with olive oil [35 mg 18:1/(kg body weight.d)], and then were randomly assigned to either flaxseed or fish oil [35 mg 18:3(n-3) or 35 mg 20:5(n-3) + 22:6(n-3)/(kg body weight.d), respectively] treatments. Participants consumed each oil supplement for 3 mo. Blood samples were drawn for analysis at the end of each 3-mo period. Plasma triacylglycerol, total, LDL and HDL cholesterol concentrations, and lipoprotein fatty acid concentrations are shown. Fish oil reduced plasma triacylglycerol and increased lipoprotein levels of 20:5(n-3) and 22:6(n-3). The flaxseed oil did not alter plasma triacylglycerol level and produced small changes in 20:5(n-3) and 22:6(n-3) concentrations. Total, LDL and HDL cholesterol levels were not affected by either (n-3) fatty acid. Significant differences in plasma triacylglycerol concentrations and total and LDL cholesterol levels were found between the two dietary P/S groups after all oil treatment periods. Levels of 18:3(n-3), 20:4(n-6), 20:5(n-3), and 22:6(n-3) in LDL were also different in high vs. low dietary P/S groups for all oil treatments and in the VLDL for the olive oil and fish oil supplementation. This study indicates that low intake of purified fish oil induces changes in plasma triacylglycerol, 20:5(n-3) levels in VLDL, LDL, and HDL, and 22:6(n-3) levels in LDL and HDL that are apparent after 3 mo and which might influence atherogenicity of lipoprotein particles in normal free-living individuals.

Adult↗
PubMed1994

The ethnic elderly in Metro Toronto Hospitals, nursing homes, and homes for the aged: communication and health care.

The ethnic elderly in Canada have remained a somewhat isolated group of seniors who become known when they enter our health care system as "aliens in their own country." They face the double jeopardy of not only declining sensibilities and increasing disabilities that frequently accompany old age but also the psycho-social deprivation of being unable to communicate with caregivers in their institutional health care settings. Communication may be critical to effective, efficient, and equitable health care service delivery for ethnic elderly individuals. This study attempts to develop a database on the ethnic elderly persons, examine the extent of communication problems they face in hospitals, nursing homes, and homes for the aged in Metro Toronto, and report on the institutional responses to the situation. Nursing unit supervisors who completed the questionnaires (N = 77) reported that communication was essential to the health care needs of the ethnic elderly individuals. A majority of health care institutions had developed some form of interpreter services albeit frequently informal, unprofessional, and ad hoc. Without interpreter services problems developed that in some cases were seen as critical to the health care of ethnic elderly individuals. Even with interpreter services available, problems developed, suggesting that the services provided were not effective in some cases. It is suggested that further study be conducted to examine the relative effectiveness of formal, professional, and informal interpreter services. Few institutions had workshops or training to help staff understand ethnic variations on the perceptions of illness and health.

Aged↗
PubMed1993

Clinical profile of stage D carcinoma of the prostate--a ten-year experience.

Carcinoma of the prostate has become one of the top ten malignancies in Singapore but to date, there has been little local clinical data available on the disease. This study aims to establish the clinical profile of Stage D carcinoma of the prostate in the local population. Forty-seven patients with Stage D disease treated by the department over a ten-year period, 1981-90, were studied. The majority (47.7%) fell in the age-group 66-75 years and the most common presenting symptom was bone pain (36.2%). Both acid and alkaline phosphatases were found to be poor diagnostic markers of the extent of the disease. Acid phosphatase was not elevated in 25.0% and alkaline phosphatase not elevated in 39.1% of our patients. Forty of these patients had orchidectomy and of these, ten were also treated with oral stilbesterol. Five-year survival for the orchidectomy group was 22.7% and that for the orchidectomy-plus-stilbesterol group was 23.0%. This compares well with other studies done in the West. Eight patients died within the first year of diagnosis but of those who survived, all remained symptom-free within this first year. The proportion of those who remained symptom-free fell to 25.0% of the survivors for subsequent years.

Acid Phosphatase↗
PubMed1992

Isolation of a cDNA encoding a human serum marker for acute pancreatitis. Identification of pancreas-specific protein as pancreatic procarboxypeptidase B.

A human pancreas-specific protein (PASP), previously characterized as a serum marker for acute pancreatitis and pancreatic graft rejection, has been identified as pancreatic procarboxypeptidase B (PCPB). cDNAs encoding PASP/PCPB were isolated from a human pancreas cDNA library using a combination of nucleic acid hybridization screening and immunoscreening with antisera raised against native PASP. The deduced amino acid sequence of PASP/PCPB cDNA predicts the translation of a 416-amino acid preproenzyme with a 15-amino acid signal/leader peptide and a 95-amino acid activation peptide. The proenzyme portion of this protein has 76% identity with rat PCPB and 84% identity with bovine carboxypeptidase B. DNA and RNA blot analyses indicate that human PCPB mRNA (1,400 nucleotides) is transcribed from a single locus in the human genome in a tissue-specific fashion. N-terminal sequencing of native PASP and the specific immunoreactivity of bacterially expressed PASP/PCPB with native PASP antibodies confirm the identification of PASP as human pancreatic PCPB.

Acute Disease↗
PubMed1992

Multiple basal cell carcinoma in tropical Australia.

No association between HLA DR1 and the development of multiple basal cell carcinomas (BCC) was found among patients who had lived at least two-thirds of their lives in the tropics. The percentage of patients with multiple BCCs increased with age; this was different from what has been found in people living in the temperate zone of Australia.

Adult↗
PubMed1991

CD4-binding regions of human immunodeficiency virus envelope glycoprotein gp120 defined by proteolytic digestion.

The gp120 envelope glycoprotein of human immunodeficiency virus type 1 binds the cell surface protein CD4 with high affinity. Here we report the use of proteolysis to define regions of gp120 involved in CD4 binding. Cleavage of gp120 with Staphylococcus aureus V8 protease at residue 269 or with trypsin at residue 432 destroys CD4 binding. These same sites are protected from proteolytic cleavage by bound CD4. Cleavages at 64, 144, 166, 172, and 315 do not affect binding and are not protected by bound CD4, indicating that these regions are not critical for binding CD4. All proteolytic fragments found in coprecipitates with CD4 were covalently associated via disulfides and comprised complete gp120 molecules. Previous conclusions by Nygren et al. [Nygren, A., Bergman, T., Matthews, T., Jornvall, H. & Wigzell, H. (1988) Proc. Natl. Acad. Sci. USA 85, 6543-6546] that both large and small (95-kDa and 25-kDa) V8 proteolytic fragments bind CD4, independently, are not distinguished by their experiments from the result found here that the small fragment immunoprecipitates with CD4 while disulfide-linked to the larger fragment.

Amino Acid Sequence↗
PubMed1991

Population pharmacokinetics of rectal theophylline in neonates.

The population pharmacokinetics of theophylline were studied in 35 neonates receiving aminophylline suppositories for the treatment of apnoea of prematurity. Routinely measured theophylline serum concentrations (n = 138, range 3-20 mg/L) were modelled in NONMEM according to a one-compartment model. The influence of a number of clinical and demographic factors, e.g., weight (range 0.8-2.5 kg) and postnatal age (2-80 days), on clearance/bioavailability (CL/F) and volume/bioavailability (V/F) was investigated. Both these parameters were found to significantly correlate to weight alone in a directly proportional manner: CL/F = 40 +/- 2 ml/h/kg and V/F = 1.3 +/- 0.2 L/kg. The absorption was best described by a first-order process, having a half-life of 1.6 +/- 0.7 h. The interindividual variability in CL/F was 25%, whereas the same estimates in V/F and in the first-order absorption rate constant could not be obtained. The residual variability in theophylline concentrations was modelled with additive error with an estimated standard deviation of 1.78 mg/L. From these results, it was concluded that rectal administration of aminophylline in neonates is a therapeutically acceptable alternative to oral administration. The convenience gained by rectal, compared to oral, administrations may compensate, in many instances, for the possibly slightly higher variability in CL/F of the former.

Administration, Rectal↗
PubMed1989

Detection of transforming growth factor-alpha messenger RNA in normal and chemically transformed hamster oral epithelium by in situ hybridization.

We have recently demonstrated the consistent detection of transforming growth factor alpha (TGF-alpha) in chemically transformed hamster oral tumors. By Northern blot analysis, no TGF-alpha mRNA can be detected in normal cheek pouch mucosa. The consistent expression of TGF-alpha associated with the malignant transformation in the well-defined hamster oral cancer model prompted us to hypothesize that the aberrant expression of this important cellular gene could be related to a specific stage of epithelial alteration. In situ hybridization was used to test this hypothesis. We now report that by in situ hybridization we can detect TGF-alpha mRNA in normal hamster oral epithelium and also at all stages of transformation. In all epithelium, labeling of TGF-alpha mRNA in the basal layer is more pronounced than that observed in the spinous and squamous layers. There is a significant increase of TGF-alpha mRNA labeling early in 7,12-dimethylbenz(a)anathracene-induced oral carcinogenesis. This increase is associated with morphological changes of epithelial hyperplasia or dysplasia. Although lesions exhibiting full-thickness epithelial dysplasia (carcinoma in situ) showed more labeling of TGF-alpha mRNA than do areas of lesser dysplasia, the transition to full-fledged papillary or invasive squamous cell carcinoma is not associated with further elevations of TGF-alpha expression.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1989

Detection of Ki-ras messenger RNA in normal and chemically transformed hamster oral keratinocytes.

The cheek pouch of the Syrian hamster is an excellent model for the experimental study of oral carcinogenesis. The carcinogenic chemical 7,12-dimethylbenz[a]anthracene consistently produces epidermoid carcinomas in the cheek pouch of the Syrian hamster, giving rise to characteristic histopathological lesions in a time-dependent manner. We now present experimental evidence that c-Ki-ras mRNA can be detected in all 7,12-dimethylbenz[a]anthracene-induced tumors examined (in vivo and in vitro) in this experimental oral cancer model while no detectable c-Ki-ras mRNA can be found in the normal hamster cheek pouch epithelium. Cellular synchronization experiments using a cell line (hamster cheek pouch carcinoma cell line 1) derived from one of these 7,12-dimethylbenz[a]anthracene-induced hamster oral tumors revealed that the c-Ki-ras protooncogene is expressed during the G1 phase of the cell cycle (proliferation dependent). Serum starvation and RNA synthesis inhibition experiments using hamster cheek pouch carcinoma cell line 1 cells suggest that the c-Ki-ras protooncogene is indeed quiescent in the normal hamster cheek pouch epithelium and that failure to detect its mRNA is not related to the slower proliferation of the normal epithelial cells. These results suggest that the transcription of the c-Ki-ras protooncogene is associated with malignant transformation in the cheek pouch of the Syrian hamster.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1989

TGF-alpha and EGF-receptor mRNAs in human oral cancers.

Transforming growth factor alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) have been shown to be present in most squamous cell carcinomas. Using the Syrian hamster oral cancer model, we have recently demonstrated the consistent presence of TGF-alpha and EGFR mRNAs in chemically transformed hamster oral keratinocytes. We now present evidence that in human oral cancer (in vivo and in vitro), TGF-alpha and EGFR mRNAs can also be consistently detected. No TGF-alpha mRNA can be detected in normal human oral epithelium by Northern blot analysis. These findings reinforce the use of the hamster cheek pouch as an experimental model for the study of oral cancer development, at least in reference to the possible participation of TGF-alpha in the malignant transformation process.

Animals↗
PubMed1986

Convulsant doses of penicillin shorten the lifetime of GABA-induced channels in cultured central neurones.

The influence of sodium benzylpenicillin (PCN) on membrane channels activated by gamma-aminobutyric acid (GABA) was studied in cultured spinal neurones of the mouse by the extracellular patch clamp technique. In whole-cell, current clamp recordings, concentrations of PCN above 0.2 mM significantly reduced the amplitude of the GABA response. Single channel currents activated by GABA were studied in outside-out patches of neuronal membrane. In both the absence and presence of PCN, cumulative open time distributions for GABA-activated channels were well fitted by the sum of two exponential terms, characterized by fast (tau f) and slow time constants (tau s). PCN (2mM) reduced the mean value of tau s from 4.29 +/- 0.56 ms (mean +/- s.e. mean) to 1.12 +/- 0.09 ms but had no significant effect on tau f. The mean open time of GABA-activated channels, calculated from the double exponential fits, decreased from 1.39 +/- 0.35 ms to 0.53 +/- 0.02 ms in the presence of 2 mM PCN. The reduced mean open time of GABA-sensitive channels seen in the presence of PCN may contribute to the convulsant action of the drug in vivo.

Animals↗