Biomedical subjects

C Chou

Publications and source records attributed to C Chou.

5 recordsLinked to original sources

PubMed1985

The uric acid-whewellite association in human kidney stones.

A total of twelve human kidney stones, composed almost exclusively of uric acid, whewellite and organic matrix were initially studied by x-ray (powder; single crystal), scanning and transmission electron diffraction techniques prior to as well as after exposure to 0.25 M EDTA solutions (96 hours; pH 7.1). Subsequent high-resolution scanning ion probe analyses eventually detected a phosphate phase not resolved by any of those techniques. Templates of organic matter lay above and in between the radial striations of whewellite. Often juxtaposing sets of striations are not in correct register with respect to one another. A sharp transition exists in the cores of the stones and separates an area characterized by the random deposition of whewellite from one in which the latter commences to grow in the form of radial striations. This transition is expected to be mediated by a physico-chemical and/or structural control. In laminae of organic matrix sectioned from EDTA-untreated cores well developed spherules are detected. Those superimpose on a substrate characterized by a considerable degree of crosslinking. Maximum spherule width is of the order of 0.8 micron. There is evidence of deposition in between the spherules. That deposition pattern appears to be controlled by the morphology and location of the spherules, thus suggesting that it is secondary to spherule formation.

Calcium Oxalate↗

PubMed1978

Adriamycin cardiotoxicity: early detection by systolic time interval and possible prevention by coenzyme Q10.

Recent work suggests that adriamycin (ADM) cardiotoxicity results from the depletion of coenzyme 10 (CoQ10) activity in myocardial mitochondria. CoQ10 is indispensable in the bioenergetics of coupled respiration of oxidative phosphorylation. It exists naturally in mitochondria, especially in the myocardium. Bertazzoli et al have reported a decrease in ADM-induced cardiotoxicity by CoQ10 both in vivo and in the in vitro isolated rabbit heart. The systolic time interval (ATI) (pre-ejection period/left ventricular ejection time ratio) has been shown to increase (indicating cardiac dysfunction) with increasing doses of ADM. We have noted a gradual increase in the STI in eight of ten patients receiving 200-500 mg/m2 of ADM. Two of these eight patients had congestive heart failure (CHF) at doses of 200 and 350 mg/m2. The continued daily oral administration of 50 mg of CoQ10 beginning with the first dose of ADM resulted in a decreased incidence of cardiac dysfunction, and a gradual increase in STI occurred in only two of eight patients receiving 200-400 mg/m2 of ADM. CHF was observed inone patient at a dose of 350 mg/m2. It is suggested that CoQ10 was nontoxic and did not affect the antitumor activity or modify the ADM-induced bone marrow toxicity. A prospective randomized study comparing ADM with and without CoQ10 is in progress.

Aged↗

PubMed1977

Inhibition of thyroid-stimulating hormone stimulation of protein kinase, glucose oxidation, and phospholipid synthesis in thyroid slices previously exposed to the hormone.

Prior exposure of thyroid slices to thyrotropin (TSH) induced refractoriness to subsequent stimulation of the cyclic AMP system by the hormone. Although the inhibition is incomplete, we examined whether the reduction in cyclic AMP was sufficient to alter other metabolic effects of TSH. Bovine or dog thyroid slices were incubated with or without 5-100 mU/ml TSH for 1-2h, washed, and then incubated without hormone for 1-2h. Half of the slices not exposed to TSH initially were then incubated with buffer and half were exposed to 5-100 mU/ml TSH. Slices initially incubated with TSH were also incubated with or without TSH in the third incubation. During the refractory period, TSH activation of protein kinase was inhibited even though the hormone still caused some increase in cyclic AMP concentrations. However, protein kinase activity was fully responsive to dibutyryl cyclic AMP when slices were incubated with it during the third incubation. Stimulation of glucose oxidation by TSH was significantly decreased in thyroid slices previously incubated with the hormone. During refractoriness, stimulation of glucose oxidation caused by prostaglandin E1 and dibutyryl cyclic AMP was also significantly diminished but that due to acetylcholine was not. Thus even though dibutyryl cyclic AMP could fully activate protein kinase activity during refractoriness, its effect on glucose oxidation was still inhibited, suggesting that the metabolic block responsible for this refractoriness was distal to activation of protein kinase. Stimulation of 32Pi incorporation into phospholipid by TSH and acetylcholine was also inhibited during refractoriness. Despite reduction of the stimulatory effect of TSH, binding of 125ITSH was not modified by prior incubation of thyroid slices with TSH. These results indicate that changes in the TSH receptor are not responsible for the development of refractoriness and other metabolic sites besides activation of adenylate cyclase appear to be involved.

Acetylcholine↗

PubMed1975

Cochlear microphonics generated by microwave pulses.

Oscillations at 50 kHz have been recorded from the round window of guinea pigs during irradiation by 918-MHz pulsed microwaves. The oscillations promptly follow the stimulas, outlast it by about 200 musec and measure to 50 muV in amplitude. They precede the auditory nerve's response and disappear with death. They are interpreted to be a cochlear microphonic and hence to demonstrate that the microwave auditory effect, in the guinea pig at least, is accompanied by a mechanical disturbance of the hari cells of the cochlea.

Animals↗

PubMedDate not supplied

Body composition in Chinese subjects: comparison with data from North America.

A multiple tracer dilution method measuring total body water, extracellular water, plasma volume, and red cell volume was used to study body composition. Healthy Chinese subjects were compared to a group of Chinese patients with various newly diagnosed gastrointestinal disorders scheduled for elective operation. Compositional data obtained from these groups showed no significant differences in compartmentalization, suggesting absence of major changes during the early stages of certain gastrointestinal diseases. In addition, healthy Chinese subjects were compared to a group of healthy Americans previously evaluated by similar dilutional methods. In males, body weight (kg) differed considerably (Chinese = 62.1 +/- 2.0 versus American = 72.5 +/- 4.1, p less than 0.02) and could be explained by alterations in body fat (Chinese = 12.4 +/- 1.3 versus American = 19.2 +/- 2.2, p less than 0.02) and extracellular water (Chinese = 14.4 +/- 0.5 versus American = 16.8 +/- 0.8, p less than 0.02). Functional tissue ("body cell mass") was similar in the 2 groups which suggested that Chinese have comparable body composition without an additional fat burden. The multiple tracer technique using deuterium oxide, sodium bromide, Evans dye, and Cr51 for body compositional assessment is accurate but expensive and laborious. Therefore, equally precise but more economical bedside methods are needed for routine compositional analysis.

Adult↗