Biomedical subjects
Publications and source records attributed to C S Chung.
A survey of carriers of adult T-cell leukemia virus (ATLV) detected as anti-ATLV associated antigens was made in Taiwan. Among 2545 adults aged 30 years or more examined, seropositive donors amounted to 0.9% in the Han Chinese but none in the aborigines.
A study was made to search for the morphological basis and, indirectly, the developmental basis for racial differences in risk of cleft lip with or without cleft palate CL(P) in Hawaii. A total of ten linear and three angular measurements read from anterior-posterior cephalographs were examined on 210 healthy adult Caucasian, Hawaiian, Japanese, Chinese, and Filipino subjects. Racial comparisons were made on these variables after adjusting for age and sex. Generally, the CL(P) high-risk group consisting of Japanese, Chinese, and Filipinos had smaller dimensions than Caucasians and Hawaiians in the variables (S-N, N-Ba) representing size of cranial base and the measurements of face height (N-A, N-ANS), palatal length (ANS-PNS), and mandibular length (Ar-Gn). Facial width relative to palatal length as measured by the ratio of bizygomatic diameter to palatal length showed a marked consistency with the racial differences in CL(P) risk. Possible significance of this finding is discussed in relation to development of the orofacial structure.
Three experiments were performed to investigate the role of vergence and the relationship between form and depth processes in global steropsis by comparing global and classical stereopsis. In the first experiment, the speed of stereoscopic resolution as a function of initial fixation-target distance was measured to discover the role of vergence in stereopsis with the random-dot and contoured stereograms. In the second experiment, the accuracy of form and depth discrimination as a function of fixation-target distance was measured using brief stimulus exposure (150 ms) to examine the nature of form and depth processing in global stereopsis. In the third experiment, the speed of resolving random-dot stereograms in the presence or absence of juxtaposed contoured stereograms was observed to examine the interaction of global stereopsis and classical stereopsis. The conclusions of these studies are summarized as follows: First, vergence plays a critical role in the solution of the random-dot stereograms but not in the solution of contoured stereograms. Second, performance with the contoured stereograms is better than with the random-dot stereograms in terms of both speed and accuracy. Third, in random-dot stereograms, discrimination of form is independent of and more accurate than discrimination of depth. Fourth, again for random-dot stereograms, the disparity of target relative to fixation systematically affects discrimination of form but not discrimination of depth. Fifth, a rapid reduction in reaction time over practice occurs for both types of stereograms. Finally, strong interference with the solution of the random-dot stereograms by the monocular contour occurs when the two kinds of stimuli are present simultaneously.
Two experiments are reported which demonstrate the effects of light-source position as an intervening variable upon the perception of relief in pictures. In the first experiment, it is shown that the pattern of light (attached shadow) falling upon forms that can be recognized as having unambiguous surface relief (concave and convex parts) influences the perception of forms with ambiguous surface relief. In the second experiment it is demonstrated that cast shadows may also determine the interpretation of ambiguous relief. These findings suggest that light-source position, implicitly or explicitly, mediates the interpretation of surface relief in pictures.
Insulin binding and degradation were measured at 37 C in isolated swine adipocytes. In preliminary experiments, binding decreased rapidly with increasing incubation time. This was associated with a marked increase in insulin degradation. Insulin binding was suppressed by some lots of bovine serum albumin (BSA), which suggests that some commercial preparations of BSA are contaminated with insulin-like molecules. In adipocyte suspensions, greater than 90% of the insulin degraded was due to a nonreceptor mediated process (i.e., insulin degrading activity present in the media). Despite the presence of insulin degrading activity in the media the cells were metabolically (as judged by lipogenic capacity and lactic dehydrogenase activity) and morphologically (greater than 98% excluded trypan blue) intact indicating that the cells were not leaking during the incubation. In subsequent experiments it was found that the specific step associated with transfer of cells during adipocyte isolation resulted in the release of insulin degrading activity. Implementation of a 30-min preincubation and washing sequence after adipocyte isolation removed the media insulin degrading activity, resulting in a marked reduction (approximately 70%) of insulin degradation by adipocyte suspensions. As a result of this modification, binding of tracer quantities of insulin attained steady-state binding conditions and maintained this for 2 h. These results demonstrate that techniques can be used to minimize nonreceptor mediated insulin degradation in adipocyte suspensions. As a result in vitro studies can be conducted that measure insulin binding and biological action in swine adipocytes at physiological temperatures.
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To eliminate successfully the undesirable side effects of the highly selective vagotomy, we developed a new, simpler type of vagotomy. As it was thoroughly demonstrated in dogs, myotomy of the lesser gastric curvature and fundus of the stomach denervates the parietal cell mass. Preoperative and postoperative acid studies were carried out with histamine phosphate (0.4 mg/kg given intramuscularly) and insulin injection (0.2 units/kg given intravenously). After myotomy, the curve was shifted to the right in response to histamine; insulin response was completely abolished. These results provided the basis for the treatment of duodenal ulcer in a human patient and confirmed that the operation is capable of producing satisfactory secretory inhibition. Our early experimental and clinical results have been encouraging. Therefore, we support further investigation regarding clinical application of this method in the treatment of chronic duodenal ulcers.
The apparent relief of monocularly viewed surfaces reversed when the order of light and shade was reversed relative to the position of a lamp observed the moment earlier. The pattern of shading was reversed either by illuminating from a direction opposite to that of the apparent direction of illumination or by inverting the illuminating image relative to the light source. The combination of both of these manipulations restores the original juxtaposition of light source and shading and reestablished accurate perception of relief. These results demonstrate that the perception of the relief of physical surfaces depends upon the remembered position of an apparent light source.
Insulin binding and insulin-stimulated glucose metabolism were measured in swine adipocytes isolated from adipose tissue obtained by biopsy on 4 successive days. These characteristics were also measured in adipose tissue obtained on the 5th d immediately after exsanguination. Binding of 125I-insulin was measured at three different concentrations of unlabeled insulin (0, 1, 100 ng/ml) on each day. Specific binding (pg bound . 2 X 10(5) adipocytes-1 X 90 min-1) was not different (P greater than .05) for each insulin concentration among the 5 d. Specifically bound insulin increased (P less than .05) with increasing insulin concentration. The effects of insulin (0, 1, 100 ng/ml) on glucose oxidation and glucose conversion to lipid were also examined in biopsy (B) and postmortem (PM) adipocytes. For a respective insulin concentration, there was no difference in glucose oxidation or lipid synthesis over the 5-d (four B, one PM) sampling period. Lipid synthesis was stimulated by the presence of insulin (P less than .05; 1 and 100 ng/ml) when compared with basal incubations; however, glucose oxidation was unaffected by the presence of insulin. There was no difference in lipid synthetic rates between 1 and 100 ng/ml of insulin. The responsiveness of glucose oxidation and lipid synthesis to insulin in PM samples was identical to that for adipocytes from B samples. These results indicate: 1) that glucose metabolism and insulin binding to adipocytes isolated from swine adipose tissue obtained by biopsy did not differ from that in tissue samples obtained shortly after death and 2) that insulin-stimulated glucose metabolism and insulin binding did not fluctuate appreciably over a 5-d period when adipose tissue was obtained at the same time each day.
In a prospective study the rate of ectopic pregnancies of women with prior induced abortion was contrasted to two sets of comparison groups: a large set of unmatched observations and a smaller subset of matched and refined data. The crude rates of ectopic pregnancy among 4004 abortion and 98,316 control pregnancies, excluding repeat pregnancies of the same women, were 0.57% and 0.49%, respectively. No significant association was detected between history of induced abortion and ectopic pregnancy based on the chi 2 analysis on unmatched data stratified by maternal age and marital status (relative risk = 1.18, 95% confidence limits (CL) 0.57-1.79) or the multivariate logistic regression analysis on the smaller set of data (relative risk = 1.34, 95% CL 0.66-2.72). Within pregnancies of the induced abortion group the risk of ectopic pregnancy was not related to abortion procedure, use of laminaria, number of prior induced abortions, or length of gestation at time of abortion. However, there was a clear association between the presence of post-abortion infection or retained secundines and ectopic pregnancy with a fivefold increase for those pregnancies of women with a history of these complications over those without these complications within the induced abortion cohort.
The effect of induced abortion on spontaneous pregnancy loss in subsequent pregnancies was studied based on 3,416 pairs of matched data in a follow-up investigation. Pregnancy outcome was examined also in relation to abortion procedure, gestation length at time of abortion, and number of previous abortions. In general there was no significant association between prior induced abortion and risks of pregnancy loss with the relative risks of 1.10, 0.88, and 0.81 for the first to third trimester respectively. A slight increase of first-trimester spontaneous loss was noted with the D&C/Suction procedure and early induced abortion (less than 9 weeks). The D&C procedure was associated with non-significant increase of second-trimester loss with the relative risk of 1.59.
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To establish the race-specific norms and investigate the underlying etiological basis of racial differences in malocclusion, cephalometric measurements of Steiner were analyzed for five major racial groups in Hawaii: Caucasians, Japanese, Chinese, Filipinos, and Hawaiians. Subjects consisted of 210 healthy and orthodontically normal individuals of both sexes aged 15 years or older. Analysis of age- and sex-adjusted cephalometric values showed that bone-to-bone relationships are largely comparable among races with an exception of GoGn/SN. Significant racial differences are incisal inclinations in relation to the maxilla, the mandible, or the opposite incisors, with the least inclination for Caucasians and the greatest for Chinese. The result is general tendency of bimaxillary protrusion of non-Caucasians. No significant differences were detected in arch lengths of both jaws among these groups. It is suggested that the observed higher prevalence of mesioclusion in non-Caucasians--especially Orientals--is due to an imbalance of tooth dimension to the alveolar bone.
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The technique of Rodbell (J. Biol. Chem. 239: 375) was modified considerably in order to isolate swine adipocytes without rupturing large cells. Cell size and diameter distributions were the same for adipocytes fixed with OsO4 following isolation with collagenase and adipoctes liberated from OsO4-fixed adipose tissue slices. Lipogenic rates were greater for isolated adipocytes compared with thin adipose tissue slices at low (0.5 mM) and high (10 mM) glucose concentrations (cells = 307 and 1100; slices = 139 and 744 nMoles glucose leads to lipid/10(6) cells/hr for 0.5 and 10 mM glucose, respectively, P less than 0.001). Similar differences were found for glucose oxidation. Sensitivity to insulin was determined by measuring the stimulation of lipogenesis and glucose oxidation in the presence of 0, 1, 5, 25, and 100 ng/ml of purified porcine insulin at low (0.5 mM) and high (10 mM) glucose concentrations. Relative to basal incubations, the addition of insulin caused similar increases in glucose oxidation and lipogenesis for isolated adipocytes and adipose tissue slices when glucose concentration was 10 mM. These results indicate 1) that isolated swine adipocytes can be prepared without alterations in cell size or diameter distribution, and 2) that isolated adipocytes have higher rates of glucose oxidation and lipogenesis from glucose even though they retain a similar in vitro sensitivity to insulin.
Diagnostic X-ray examinations as a potential risk for neoplasia were investigated in a prospective study of 55,908 women who participated in the Collaborative Perinatal Project of the National Institute of Neurological and Communicative Disorders and Stroke. The X-ray exposure histories of 145 mothers whose children developed neoplasms and 290 matched controls were examined. Of the childhood neoplasms, 40 were malignant and 105 were benign. Generally, the data were consistent with increased risk of malignant neoplasms among children of women exposed to X-rays before and during pregnancy, with a somewhat higher relative risk estimate for preconception exposure. No significant association of X-ray exposure and benign neoplasms was detected.
Family data were collected on a multi-ethnic cohort of hospitalized schizophrenics in Hawaii in 1942. Results showed that prevalence rates for Orientals were significantly higher (p less than 0.001) than rates for Caucasians, Polynesians and others. Complex segregation analysis using a generalized mixed genetic model was performed on 507 sibships collected under both complete and incomplete selection. Likelihood ratio tests between the generalized model and two subhypotheses of a major gene effect and a polygenic effect revealed that neither subhypotheses could be rejected at the 5% level of significance. While neither hypothesis could be adequately supported by the likelihood ratio test, certain aspects of the findings suggest a preference for the multifactorial model in explaining the inheritance of schizophrenia in these data.