Biomedical subjects
Publications and source records attributed to H Kim.
Some hospitals in earthquake-prone California may be sound financially, but their location on a major fault line can be enough to make bond insurance firms steer clear of the area. The insurers see the faults as constant threats to an institution's bond repayment ability.
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Located in San Francisco's densely populated Chinatown district is Chinese Hospital, a small, acute-care facility that has a long tradition in the community. The hospital's mission is to mix modern medical care with touches of the traditional Chinese culture, all the while dealing with the pressing economic problems facing most U.S. hospitals.
A 13C NMR study is reported of switch variant anti-dansyl antibodies developed by Dangl et al. [(1982) Cytometry 2, 395-401], who had used the fluorescence-activated cell sorter to select and clone these variants. These switch variant antibodies possess the identical VH, VL, and CL domains in conjunction with different heavy chain constant regions. In the present study, switch variant antibodies of IgG1, IgG2a, and IgG2b subclasses were used along with a short-chain IgG2a antibody, in which the entire CH1 domain is deleted. The switch variant antibodies were specifically labeled with [1-13C]methionine by growing hybridoma cells in serum-free medium. Assignments of all the methionyl carbonyl carbon resonances have been completed by using the intact antibodies along with their fragments and recombined proteins in which either heavy or light chain is labeled. A double labeling method [Kainosho, M., & Tsuji, T. (1982) Biochemistry 21, 6273-6279] has played a crucial role in the process of the spectral assignments. The strategy used for the assignments has been described in detail. In incorporating 15N-labeled amino acids into the antibodies for the double labeling, isotope dilution caused a serious problem except in the cases of [alpha-15N]lysine and [15N]threonine, both of which cannot become the substrate of transaminases. It was found that beta-chloro-L-alanine is most effective in suppressing the isotope scrambling. So far, spectral assignments by the double labeling method have been possible with 15N-labeled Ala, His, Ile, Lys, Met, Ser, Thr, Tyr, and Val.(ABSTRACT TRUNCATED AT 250 WORDS)
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We report that parthenogenetic activation (pronuclear formation) is induced during in vitro culture of recently ovulated (13-14 hr post-hCG) mouse oocytes in pyruvate deficient medium. Pronuclear formation occurred when oocytes were cultured in medium containing 1/10X (Pyr-) or lower concentrations of pyruvate but failed to occur either in oocytes cultured in the presence of 0.47 mM (1X, Pyr+) or 1/2X pyruvate or in oocytes cultured in the absence of pyruvate but with cumulus cells. Pronuclear formation was evident within 8 hr of culture and completed by 16 hr and remained intact during continuous culture in Pyr- medium. Transfer of pronuclear oocytes to Pyr+ medium resulted in pronuclear membrane disassembly and further parthenogenetic development. A similar incidence of parthenogenetic activation occurred when recently ovulated oocytes were cultured in the presence of cycloheximide but not following ethanol or hyaluronidase treatment. However, both ethanol and hyaluronidase induced pronuclear formation in in vivo aged oocytes. Results suggest that the type of activation induced varies with the age of the oocyte and the nature of the stimulus. Amino acid uptake ([35S]methionine) by oocytes was unaffected by Pyr- culture whereas incorporation into protein was markedly inhibited. Gel electrophoretic analysis of labeled egg extracts revealed a marked inhibition of egg protein synthesis after 4 hr of culture in Pyr-. The occurrence of a cortical reaction was monitored by binding of fluorescent labeled lectin to the oocyte surface. A cortical reaction occurred in response to ethanol treatment of freshly ovulated and in vivo aged oocytes cultured in Pyr+ medium but not in pronucleate oocytes induced by Pyr- culture. Suppression of ethanol-induced cortical reaction by Pyr- culture was restored following transfer of oocytes to Pyr+ medium. Results demonstrate that nuclear events as well as plasma membrane events can be simply regulated by controlling the amount of energy substrate available to the germ cell. Effects of Pyr- culture in inducing pronuclear formation appear to be mediated in a large part via inhibition of protein synthesis.
We have followed the fate of acetylated alpha-tubulin during microtubule (MT) purification from both gray matter- and white matter-enriched bovine brain regions, using quantitative immunoblot assays employing well characterized monoclonal antibodies specific for acetylated alpha-tubulin and all beta-tubulins. Our results show that crude homogenates from both gray matter and white matter brain regions contain the same proportion of acetylated alpha- to total tubulin. We have found that the acetylated isoform cycles more efficiently with MTs from gray matter than with MTs from white matter. However, the resultant purified MT preparations from both gray and white matter regions are greatly depleted in the acetylated isoform compared to the tubulin in the initial homogenates because most of the acetylated alpha-tubulin from both tissue sources partitions with the cold-insoluble fraction of the initial brain homogenate. A low percentage of the acetylated alpha-tubulin in brain homogenates does become incorporated into MTs initially, but this subpopulation of acetylated alpha-tubulin then becomes associated with a cold- and calcium-insoluble fraction of the MT preparation. These results demonstrate that the standard brain MT and tubulin preparations used by most investigators for in vitro studies are greatly depleted in acetylated alpha-tubulin, and thus provide poor model systems for the analysis of the function of this tubulin isoform.
In the absence of a suitable energy source, mouse oocytes cultured in vitro resume, but fail to complete, meiotic maturation. However, little is known about the underlying mechanisms leading to this meiotic failure. We utilized pyruvate-deficient medium to test for the role of pyruvate throughout the meiotic maturation process. Germinal vesicle-stage (GV) oocytes underwent germinal vesicle breakdown (GVBD), but failed to form a polar body when cultured continuously in pyruvate-free medium. However, when GV oocytes were preincubated for 4 h in pyruvate-free medium containing dibutyryl cyclic adenosine monophosphate (dbcAMP) and then cultured in pyruvate-free medium, GVBD was markedly inhibited. Preincubation of GV oocytes in dbcAMP and cycloheximide, followed by culture in cycloheximide only, also inhibited GVBD. A longer preincubation period was required in the cycloheximide-dbcAMP case (12 h) than in pyruvate-free-dbcAMP medium situation (4 h). Strikingly, reassembly of the nuclear membrane without polar body formation was observed following GVBD in oocytes continuously cultured in pyruvate-free medium. The reassembled nuclear membrane increased in size with continued culture, and it surrounded partially-decondensed chromatin. Nuclear membrane reassembly also occurred in oocytes which had undergone GVBD during continuous culture in medium containing only cycloheximide. Reformation of nuclear membranes after GVBD was confirmed by electron-microscopic analyses of oocytes cultured in pyruvate-free medium or in the presence of cycloheximide.(ABSTRACT TRUNCATED AT 250 WORDS)
Vertebrate lenses show remarkably taxon-specific patterns of protein composition, most obviously in the recruitment of enzymes as major crystallins. Phylogenetic relationships are particularly apparent in mammals. Here we describe eta-crystallin, which is probably identical to cytosolic aldehyde dehydrogenase, lens-specifically expressed at high abundance in the elephant shrews, primitive eutherians of the family Macroscelidae, and mu-crystallin, a novel lens protein expressed in some marsupials. We have also observed that enzymes that have been recruited as crystallins in some species are also moderately abundant in the lenses of other species. This hints that the origins of enzyme-crystallins may lie in a pool of enzymes widely expressed in lenses at fairly high levels, perhaps because they have important developmental or functional roles in the tissue.
A number of studies have reported correlations between subjects' asymmetry scores on left and right hemisphere specialized tasks. In this paper we report the results of meta-analyses performed on these correlations. Results showed positive correlations between subjects' asymmetry scores on left and right hemisphere specialized tasks in both modalities (asymmetry scores were computed as R-L for both left and right hemisphere specialized tasks). Thus, in both modalities, some of the between-subjects variability in asymmetry scores appears to reflect non-stimulus specific individual differences in perceptual asymmetry. For the visual asymmetry tasks, results also showed that the subjects' asymmetry scores on left and right hemisphere specialized tasks were more highly correlated under conditions of bilateral than unilateral input. This finding suggests that bilateral tasks may be more sensitive to "characteristic perceptual asymmetry" than unilateral tasks.
Sixty-three subjects (31 dextrals and 32 sinistrals) were given two visual half-field laterality tasks (recognition of words and faces). Subjects were classified as having typical or atypical hemispheric specialization on the basis of the relative magnitude of their asymmetry scores on the two laterality tasks. Those subjects whose word asymmetry scores were larger than their face asymmetry scores (asymmetry scores computed as RVF-LVF for both tasks) were classified into Group Typical and those subjects whose word asymmetry scores were smaller than their face asymmetry scores were classified into Group Atypical. For both dextrals and sinistrals, the proportion of subjects classified into Groups Typical and Atypical was consistent with estimates of the incidence of typical and atypical hemispheric asymmetry patterns based on sodium amytal testing. These results support the hypothesis that the relative magnitude of asymmetry scores on left and right hemisphere specialized tasks index individual differences in patterns of hemispheric specialization.
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Flow cytometric studies were performed on peripheral blood obtained before, during, and subsequent to urologic surgery. The results suggest that 7 of 11 patients had a brief period during surgical manipulation when they had cells from the primary surgical site in the peripheral blood. Concentration of such cells was generally less than 10(2)/mL even during the intraoperative period. These findings suggest that perioperative tumor seeding is a real concern, and that flow cytometry can be used to study maneuvers to reduce its incidence.
The effects of intravesical instillations of thiotepa, mitomycin C and adriamycin on the normal urothelium were studied in rats. Changes in the bladder wall in the form of fibroblastic atypia and submucous fibrous plaques were significant in the mitomycin C treated group. In 46% of mitomycin C treated animals there was urothelial atypia and in one animal, the atypia was severe enough to resemble carcinoma in situ. None of the rats treated with thiotepa showed intramural fibrous plaques or fibroblastic atypia and only 8% showed urothelial atypia. In the group treated by adriamycin instillation, 17% showed intramural fibrous plaques, but none showed urothelial atypia or fibroblastic atypia. The fibroblastic atypia and submucosal fibrous plaques seen in the mitomycin treated group may explain the reduced bladder capacity seen in the clinical setting.
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