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Biomedical subjects

R Wong

Publications and source records attributed to R Wong.

At least 163 records · Page 9Linked to original sources
PubMed1990

Metabolism of normal skeletal muscle during dynamic exercise to clinical fatigue: in vivo assessment by nuclear magnetic resonance spectroscopy.

In vivo nuclear magnetic resonance (NMR) spectroscopy was used to define several intracellular high energy phosphate variables of the gastrocnemius muscle of normal subjects during rest, graded plantar flexion exercise to exhaustion, and recovery. There were nine males and eight females with an average age of 34 +/- 8 years. At rest, pH averaged 7.09 +/- 0.03 and the energy cost index (ECI)--the ratio of inorganic phosphate to phosphocreatine--averaged 0.13 +/- 0.03. At peak exercise, the ECI increased markedly to 2.71 +/- 2.0 (P less than 0.001) and pH fell precipitately to 6.76 +/- 0.17 (P less than 0.001), indicating the high intensity of the exercise. Exercise endurance averaged 12 +/- 5 mins; it was not highly correlated with sex, age (r = 0.35), rest pH (r = 0.26), rest ECI (r = 0.38), peak exercise pH (r = 0.23) or peak exercise ECI (r = 0.38), nor exercise changes in pH (r = 0.17) and ECI (r = 0.28). At 23 mins post exercise all variables were similar to rest. Rest pH was the only variable different between males (7.10 +/- 0.03) and females (7.07 +/- 0.03) (P less than 0.05). Thus, dynamic exercise of large skeletal muscles in normal subjects was characterized by marked temporal changes in high energy phosphate profiles and very low pH at exhaustion. No single metabolic variable correlated highly with exercise endurance, suggesting that the intracellular pathophysiology of exhaustive muscle exercise and clinical fatigue may be multifactorial.

Adult↗
PubMed1990

Histopathological sinus node classification and its relation to coronary atherosclerosis using an atherometric system.

Studies were conducted into 100 consecutive subjects (autopsy material), 53 men and 43 women between 31 and 70 years old, who had died a natural death. The HUDSON-procedure was used for histopathological analysis of the cardiac conducting system (CCS). About 48 microscopic slides of each subject, including sinus node (SN) tissue, were inspected by 4 pathologists in a blind study. The findings were classified by 3 different groups according to histopathological data of the SN, viz. changes and distribution of P and T cells, stroma, artery, and innervation of SN. The 3 major epicardial branches of coronary arteries were prepared for morphometric studies by WHO standards. A digitizer coupled to a microcomputer LTEL (Cuba, IBM-compatible) was used for quantitative evaluation of atherosclerotic lesions (AL), and all data were subsequently processed on the same computer, using a statistical commercial package (Number Cruncher Statistical System) for results. An atherometric system was used and proved to be a properly standardized methodology, suitable to characterize AL in any vascular sector or group of patients. The most remarkable results were as follows: Three-group classification was useful in estimating the association between pathomorphological data of SN and coronary atherosclerosis. The atherometric system proved to be a powerful tool to study and characterize atherosclerotic lesions in coronary arteries.

Adult↗
PubMed1989

DNA content of rectal scrapings from individuals at low and high risk for the development of colorectal cancer. A feasibility study.

Scrapings of superficial rectal mucosa were collected from 31 patients with colorectal carcinoma, 66 patients with sporadic adenoma, and 53 control subjects with no personal or family history of colorectal cancer. The DNA ploidy level and proliferative patterns of each specimen were analyzed by flow cytometry (FCM). A GMS index, calculated as the ratio of G2 + M:S, was found to be significantly lower in control subjects than in any of the high-risk groups studied. Aneuploidy was more prevalent in rectal scrapings from cancer patients and adenoma patients than in those from control subjects. Aneuploid cell populations were detected in apparently normal rectal scrapings from two control subjects. Some high-risk individuals (i.e., cancer patients and patients with adenomas and a family history of cancer) exhibited higher proportions of tetraploid (designated G2/M) cells and a higher G2/M:S phase ratio than control subjects. The results accumulated thus far show that the rectal scraping procedure is safe and easy to perform. Our limited findings give hope that the DNA content analysis of cells obtained by rectal scraping may eventually prove useful in mass screening for colorectal cancer risk. However, definitive evaluation will require further refinement and elaboration of analytic technique and testing on more patients at various levels of predetermined risk.

Adenoma↗
PubMed1989

An immunodeficiency characterized by defective signal transduction in T lymphocytes.

We studied a nine-year-old boy with severe, recurrent infections. The patient was exposed in utero to azathioprine and prednisone. He had autoimmune hemolytic anemia, bronchiectasis, and Hodgkin's disease. The patient's circulating lymphocytes were normal in number and phenotype, but stimulation of the T-cell receptor by antigens, mitogens, and monoclonal antibodies failed to induce interleukin-2-receptor expression, interleukin-2 synthesis, or lymphocyte proliferation. The early biochemical events necessary to initiate lymphocyte activation--accumulation of the second messenger diacylglycerol, activation of the enzyme protein kinase C, and elevation of the free intracellular calcium concentration--failed to occur in this patient's lymphocytes. The defect in the lymphocyte could be corrected in vitro by two agents that bypass the receptor-mediated signal mechanism (the diacylglycerol analogue phorbol and the calcium ionophore ionomycin). Further studies localized the defect in signal transduction to the interaction between cell-surface receptors and the guanine nucleotide-binding protein. We conclude that this patient's immunodeficiency was caused by a defective coupling of surface receptors to signal-transducing proteins in his T lymphocytes, resulting in failure of lymphocyte activation.

Calcium↗
PubMed1989

Oral dextran sulfate (UA001) in the treatment of the acquired immunodeficiency syndrome (AIDS) and AIDS-related complex.

STUDY OBJECTIVE: To evaluate the tolerance and safety of oral dextran sulfate (UA001), a potent in-vitro inhibitor of human immunodeficiency virus (HIV) in patients with the acquired immunodeficiency syndrome (AIDS) and AIDS-related complex. DESIGN: Unblinded, dose-escalation 8-week trial. SETTING: An AIDS outpatient clinic of a university-affiliated municipal hospital. PATIENTS: Thirty-four patients with stage III or IV HIV infection were enrolled. Five patients in six different dosage cohorts completed the study. The population was predominantly homosexual men with persistent generalized lymphadenopathy (stage III). INTERVENTIONS: Oral dextran sulfate was given three times daily in total daily doses of 900 to 5400 mg for 8 weeks. Patients were monitored for tolerance and toxicity. Immunologic and virologic values were also followed. MEASUREMENTS AND MAIN RESULTS: Oral dextran sulfate was given without significant side effects. The commonest minor subjective complications were mental hyperexcitability and gastrointestinal complaints. The most frequent laboratory abnormalities were leukopenia and hepatic transaminase elevations. Eleven patients required dose reductions, and therapy was stopped in 4 because of toxicities. The CD4 lymphocyte numbers did not change appreciably. No decline in beta-2 microglobulin levels occurred. The HIV antigen levels were unchanged from baseline. No assay for dextran sulfate plasma levels has yet proven successful. CONCLUSIONS: Oral dextran sulfate appears to be well tolerated. No evidence of systemic absorption of the parent compound is available. However, in view of the promising in vitro effects and acceptable toxicity, oral dextran sulfate as a potential antiretroviral agent continues to be studied.

AIDS-Related Complex↗
PubMed1989

Endodontic effects of root planing in humans.

Although the deliberate removal of cementum by root planing remains part of periodontal therapy, its scientific basis is under challenge. A potentially harmful effect of root planing is the exposure of dentinal tubules to the oral environment; this study investigated the short-term endodontic effects of root planing in humans. Ten teeth with significant loss of periodontal attachment had one proximal surface root planed; the other proximal surface was not root planed. After 10-14 days, the teeth were extracted and processed for light microscopic and SEM examination. Hypersensitivity to thermal stimuli was reported by 4 subjects after root planing. Chronic pulpitis was found in 3 pulps adjacent to the area of root planing. Bacterial penetration of dentin was observed, although the depth of penetration was less than reported by others. The results indicated that previous perceptions of the beneficial role of root planing in periodontal therapy require reconsideration.

Dental Prophylaxis↗
PubMed1988

Complete structural determination of lipopolysaccharide obtained from deep rough mutant of Escherichia coli. Purification by high performance liquid chromatography and direct analysis by plasma desorption mass spectrometry.

Lipopolysaccharide (LPS) extracted from the deep rough mutant of Escherichia coli D31m4 was disaggregated with 0.1 M EDTA, pH 7.0, and fractionated on a diethylaminoethyl-cellulose column to yield the biphosphate form of LPS. After methylation, the derivative was purified by reverse-phase high performance liquid chromatography using a C18-bonded silica cartridge. A linear gradient of 50-100% isopropyl alcohol/water (93:7, v/v) in acetonitrile/water (93:7, v/v) was used over a period of 60 min. The derivatized LPS showed a single major peak by high performance liquid chromatography, and this hexamethyl hexaacyl LPS was recovered and subjected to chemical analysis, plasma desorption mass spectrometry, and nuclear magnetic resonance (NMR) spectroscopy. Chemical analysis of the purified hexamethyl LPS quantitated certain key chemical compositions. Plasma desorption mass spectrometry showed a molecular ion (M + CH2 + Na)+ at m/z 2360, which established the molecular formula and Mr to be C116H214N2O39P2 and 2323, respectively. Thus, it contained two each of glucosamine, 2-keto-3-deoxyoctonate, and phosphate; four beta-hydroxymyristates; one laurate; and one myristate. NMR spectroscopy confirmed the locations of the four ester-linked fatty acyl groups. Based on these results and the known structure of free lipid A, the complete structure of the deep-rough chemotype LPS from E. coli can now be presented with confidence. This is the first report of a successful purification to homogeneity and the characterization of the simplest of the LPS at the intact level. This study shows that the natural distribution of the lipid A moiety of LPS from E. coli D31m4 is hexaacyl/pentaacyl in a molar ratio of greater than 90:less than 10. Acid hydrolysis of LPS causes the formation of the lower homologues of the free lipid A.

Chemical Fractionation↗
PubMed1988

Covalent change in alpha crystallin during human senile cataractogenesis.

The high molecular weight aggregates (HMWA) obtained from normal and cataractous human lens nuclei have been resolved by SDS-polyacrylamide gel electrophoresis, and the alpha crystallin band has been probed with antisera made against the whole alpha crystallin molecule and with antisera made against synthetic peptides of alpha crystallin (alpha A2 147-161 and alpha A2 163-173). Quantitation of these antisera binding demonstrated that the anti-alpha A2 163-173 serum and the anti-alpha whole sera bound equally well to the alpha crystallin band from the HMWA fraction from normal and cataractous lenses. In contrast, the anti-alpha A2 147-161 serum bound little, if at all, to alpha crystallin from normal lenses, while it bound well to alpha crystallin from cataractous lenses. These results demonstrate a covalent alteration in the alpha crystallin molecule, and suggest a possible location of a covalent change that may occur during the cataractogenic process in the aged human lens.

Aged↗
PubMed1988

Mitochondrial DNA molecules and virtual number of mitochondria per cell in mammalian cells.

A new biochemical method for estimating the virtual number of mitochondria (mt) per cell was developed and used together with a plasmid probe to measure mt DNA/mitochondrion and mt DNA/cell. These methods were used in five cell types from four mammalian species. Mt DNA/mitochondrion was essentially constant in all cell types (mean 2.6 +/- 0.30 SE mitochondrial DNA molecules/mt). Mt DNA molecules/cell encompassed an eight-fold range between various cell types (low 220 +/- 6.2; high 1,720 +/- 162 mt DNA molecules/cell). Virtual mt number/cell ranged from 83 +/- 17 to 677 +/- 80 (SE) mt/cell in various cell types. All five mammalian virtual mitochondria contained the same genomic mass. The number of virtual mitochondria per cell and amount of mt DNA per cell appear to be closely regulated within a given cell type but differ widely from cell type to cell type.

Animals↗
PubMed1988

Defensive aggression and testosterone-dependent intermale social aggression are each elicited by food competition.

Castrated rats with medial hypothalamic lesions or sham lesions and castrated rats with testosterone implants or sham implants were placed on a 23-hr food deprivation schedule, adapted to a highly palatable liquid food, and then housed in pairs. The pairs were observed in competition for the highly palatable food over a 4-min period on each of six days. On the first three days, the food was dispensed in a way that allowed only one animal at a time to drink while during the second three days both animals could drink simultaneously. The pairs of animals were then separated, individually adapted to a bland liquid food, and paired with a different animal for a second series of competition tests. With highly palatable food as the incentive, rats made hyperdefensive by medical hypothalamic lesions were more successful at maintaining access to the food and more aggressive than their sham-lesioned competitors on tests when food access was restricted to a single animal but not on tests when both animals could drink simultaneously. With bland food as the incentive, lesioned animals were not consistently more successful in maintaining access to the food but were significantly more aggressive than their cagemates. With the highly palatable food, castrated males with testosterone implants were neither more successful in maintaining access to the food nor more aggressive than their cagemates with sham implants. However, when paired with an unfamiliar cagemate in preparation for competition tests with the bland food, most rats with testosterone implants attacked the new cagemate using a lateral attack and displaying piloerection.(ABSTRACT TRUNCATED AT 250 WORDS)

Aggression↗
PubMed1988

High molecular weight aggregate from cataractous and normal human lenses: characterization by antisera to lens crystallins.

High molecular weight and low molecular weight fractions were obtained from total soluble proteins of human cataractous and normal lens nuclei. These fractions were analyzed using a solid phase radioimmunoassay that employed monospecific antisera to alpha, beta and gamma crystallins. Relative to the high molecular weight fraction from normal lens nuclei, the high molecular weight fraction from cataractous lens nuclei showed decreased binding to antisera specific for beta and gamma crystallins. These results demonstrate that the polypeptides of the high molecular weight fraction comprise a special class of polypeptides that have preferentially undergone covalent and/or structural changes during the process of human cataractogenesis.

Cataract↗
PubMed1988

2-D echocardiographic analysis of interventricular septal motion: concept of an anterior and posterior part to the septum.

2-D echocardiography was performed in 50 patients with transmural anteroseptal (group 1) or inferior myocardial infarction (group 2). Twenty-four patients with myocardial infarction had diagnostic coronary arteriography. Twenty-five normal subjects served as controls. The interventricular septum was subdivided into proximal and distal halves. In the parasternal long axis view (PSLAX), interventricular septum asynergy was seen in 96% of patients of group 1 and none in group 2. In the apical four chamber view (A4C), the proximal interventricular septum was abnormal in 48% of group 2 patients, but only one patient in group 1. The distal half of the interventricular septum in the A4C was abnormal in 48% of patients in group 1 and 12% in group 2. Complete asynergy of the interventricular septum in the PSLAX view was seen in 80% of patients with proximal stenosis in the left anterior descending artery (LAD) in association with anteroseptal myocardial infarction. Distal asynergy in this view was noted in all patients with a stenosis distal to the first septal perforator. In conclusion, the PSLAX visualizes the anterior interventricular septum and demonstrates wall motion abnormalities associated with anteroseptal infarction; complete asynergy of the interventricular septum in the PSLAX view suggests an anteroseptal infarction with proximal LAD stenosis; the A4C visualizes the posterior interventricular septum and proximal wall motion abnormalities are seen in inferior infarction while distal septal wall motion abnormalities occur in anteroseptal or inferior infarction.

Adult↗