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Biomedical subjects

C H Lo

Publications and source records attributed to C H Lo.

36 records · Page 2Linked to original sources
PubMed1988

Biochemical comparison of lens crystallins from three reptilian species.

Lens crystallins were isolated from the homogenates of reptilian eye lenses derived from three different species by gel-permeation chromatography and characterized by gel electrophoresis, amino-acid analysis, N-terminal sequence analysis and circular dichroism. Four fractions corresponding to alpha-, delta/epsilon/beta-, beta- and gamma-crystallins were obtained for the crystallins from caiman lenses, whereas delta- and gamma-crystallin fraction were present in lesser amounts or missing in the turtle and snake lenses, respectively. The native molecular masses for these purified fractions and their polypeptide compositions were determined by gel filtration and SDS-gel electrophoresis, respectively, revealing the typical subunit compositions for each classified crystallin. The spectra of circular dichroism indicate a predominant beta-sheet structure in alpha-, beta- and gamma-crystallins, and a major contribution of alpha-helical structure in delta/epsilon-crystallin fraction, which bears a resemblance to the secondary structure of delta-crystallin from the chicken lenses. Comparison of the amino-acid contents of each orthologous class of reptilian crystallins with those of evolutionary distant species still exhibited similarity in their amino-acid compositions. N-terminal sequence analysis of the crystallin fractions revealed that all fractions except that of gamma-crystallin are N-terminally blocked. Extensive sequence similarity between the reptilian gamma-crystallin polypeptides and those from other vertebrate species were found, which establish the close relatedness of gamma-crystallins amongst the major classes of vertebrates.

Alligators and Crocodiles↗
PubMed1988

N-terminal sequences of gamma-crystallins from the amphibian lens and their homology with gamma-crystallins of other major classes of vertebrates.

gamma-Crystallins were isolated from the homogenate of frog eye lenses (Rana catesbeiana) by exclusion gel chromatography and further purified by cation-exchange chromatography. They were the only group of crystallins possessing free amino groups amenable to sequence analysis by Edman degradation. Comparison of the amino acid contents of the purified subfractions of gamma-crystallins indicated their close relatedness in amino acid compositions and probably sequence homology as well. The amino-terminal sequence analysis of the purified gamma-crystallin subfractions showed extensive homology between these amphibian gamma-crystallin polypeptides themselves and also those from other vertebrate species, suggesting the existence of a multigene family and their close relatedness to gamma-crystallins of other vertebrates. The sequence comparison of the gamma-crystallin polypeptides from all major classes of vertebrates has provided strong support for the divergent evolution of gamma-crystallin family.

Amino Acid Sequence↗
PubMed1987

Sequence comparison of gamma-crystallins from the reptilian and other vertebrate species.

Lens crystallins were isolated from homogenates of reptilian eye lenses (Caiman crocodylus apaporiensis) by gel-permeation chromatography and characterized by gel electrophoresis, and amino acid and N-terminal sequence analyses. Four fractions corresponding to alpha-, delta/epsilon/beta-, beta- and gamma-crystallins were identified on the basis of their electrophoretic patterns as revealed by SDS gel electrophoresis. Comparison of the amino acid contents of reptilian crystallins with those of mammals suggests that each orthologous class of crystallins from the evolutionarily distant species still exhibits similarity in their amino acid compositions and probably sequence homology as well. All fractions except that of gamma-crystallin were found to be N-terminally blocked. N-terminal sequence analysis of the purified gamma-crystallin subfractions showed extensive homology between the reptilian gamma-crystallin polypeptides themselves and also those from other vertebrate species, suggesting the existence of a multigene family and their close relatedness to gamma-crystallins of other vertebrates.

Alligators and Crocodiles↗
PubMed1979

Physical properties of human serum hexosaminidases A and B: studies in normal and cancer patients.

The major forms of human serum hexosaminidases A and B (Hex A and Hex B) were isolated from normal subjects and cancer patients using DEAE-cellulose. In normal serum, Hex A was heat-labile and had an apparent KM of 1.13 mM and Vmax of 0.51 mumol/ml/h; Hex B was heat-stable and had an apparent KM of 0.85 mM and Vmax of 0.22 mumol/ml/h. Both forms had the same pH optimum, at 4.3. Hex A and Hex B from the sera of cancer patients resembled their normal counterparts in heat stability, pH optimum, and apparent KM (1.07 mM for Hex A, 0.88 mM for Hex B). In contrast, the Vmax values for the cancer sera isozymes were greater than those of normal sera (0.70 and 0.40 mumol/ml/h for Hex A and Hex B, respectively).

Hexosaminidases↗
PubMed1978

Human serum hexosaminidase: elevated B form isozyme in cancer patients.

The activity of N-acetyl hexosaminidase (beta-2-acetamido-2-deoxy-D-glucoside:N-acetamido-deoxyglucohydrolase, E.C. 3.2.1.30) was significantly greater in sera of patients with solid malignant tumors than in sera of healthy volunteers or of patients with nonmalignant ailments. The increased activity was found in the two major isozymes, hexosaminidase A and hexosaminidase B, but the increase in the latter isozyme was more prominent than in the former. Measurement of the levels of the hexosaminidase isozymes may provide an ancillary diagnostic test for malignancy.

Adolescent↗
PubMedDate not supplied

The effects of metiamide on gastric secretion and stress ulceration in rats.

The effects of metiamide, a histamine H2 blocker, on gastric secretion and ulcer formation in stressed pylorus-occluded rats were investigated. Metiamide, like atropine, significantly reduced the volume of gastric secretion and total acid output in unrestrained pylorus-occluded rats. Both drugs produced greater decreases in the volumes of gastric secretion in stressed rats than in their corresponding unrestrained groups. Stress itself reduced both parameters. Metiamide, like atropine, significantly reduced the incidence of gastric stress ulcers. When given together these two drugs did not provide greater protection. The results obtained with metiamide indicate that histamine plays a role in basal gastric secretion and in the pathogenesis of stress ulcers. As no correlation between gastric acid secretion and ulcer formation was demonstrated in this study, it is suggested that H2 receptors may also be involved in gastric motility. However, the possibility that metiamide could exert its ulcer-protecting effects through other mechanisms cannot yet be excluded.

Animals↗
PubMedDate not supplied

The forgotten faces: the lonely journey of powerlessness experienced by elderly single Chinese men with heart disease in Taiwan.

The purpose of this study is to explore the content and background context of powerlessness experienced by elderly single Chinese men with heart disease and their coping behaviors during their hospitalization stage. Data were gathered by semi-structured interviews at a leading veterans' hospital in northern Taiwan and analyzed using a qualitative content analysis mode. Twenty-six men who were 65 or older, diagnosed with heart disease, and who lived alone during the preadmission stage were recruited. Eighty-one percent (N = 21) reported that their perceptions of powerlessness occurred either in the preadmission or hospitalization stage or were expected to occur after discharge. Other complaints of powerlessness were attributed to having no choices in appropriate living places during the preadmission stage, having no control over discomfort, being unable to obtain care and companionship from families and friends, failing to get medical information about their disease and options of treatment during hospitalization, or expecting deteriorating health and receiving no assistance during emergencies or in the dying stage after discharge from the hospital.

Adaptation, Psychological↗