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Biomedical subjects

J Liang

Publications and source records attributed to J Liang.

At least 271 records · Page 15Linked to original sources
PubMed1993

Method for measuring visual resolution at the retinal level.

To measure the intrinsic resolving capacity of the retinal and neural levels of vision, we devised a method that creates two lines with controllable contrast on the retina. The line separation can be varied at will, down to values below those achievable with conventional optical techniques. Implementation of the method with use of a He-Ne laser leads to a procedure that permits analysis of the performance of the human visual apparatus.

Humans↗
PubMed1993

[The clinical use of steady-state flash visual evoked potentials].

The authors applied 30Hz flash stimuli to record steady-state flash visual evoked potentials (FVEP) and extracted the amplitudes and phases of the first and second harmonics as the characteristic value by discrete Fourier transform (DFT). 46 normal controls (89 eyes) and 78 patients (109 eyes) were detected and analysed by this method. The result showed that the characteristic values of the normal controls are significantly different in three age groups and showed the positive in 35 eyes with the optic never diseases (82.9%), 25 eyes with age-related macular degeneration (92%), and 9 eyes with retinal detachment involved macular (100%). It indicates the method is a sensitive index to evaluate the macular visual function. After preliminary observation, the visual acuities of postoperation were found above 0.4 in cataracts (28 eyes) or opacities (12 eyes) if preoperative FVEP were normal and non-complicated, or less than 0.4 if preoperative FVEP were abnormal. This suggests the method is one of the effective index to detect the postoperative vision of the media opacities. The advantages, disadvantages and the clinical applications were discussed.

Adolescent↗
PubMed1993

Patterns of nonresponse in a national survey of elderly Japanese.

Data from a nationwide sample of older adults in Japan were analyzed to determine patterns of unit nonresponse. Maximum likelihood logistic regression analyses identified age, sex, geographic region, and urbanicity as significant predictors of response status. The probability of nonresponse was higher for men, persons living in certain regions, and those in large urban areas. Age had a curvilinear relationship with response status; the probability of nonresponse decreased from age 60 to age 70, and then increased again with the highest rates at the oldest ages. When nonrespondents were disaggregated into three different groups based on reason for nonparticipation (i.e., refusals, not-at-homes, other reasons), variation in the results was found. For example, while men were more likely than women to refuse an interview or be absent from home during the survey period, they were no more likely to not participate for other reasons. Use of different response rate calculations and a substitution sampling procedure were not found to seriously affect study results.

Aged↗
PubMed1992

Stable heparin-producing cell lines derived from the Furth murine mastocytoma.

Stable cell lines that synthesize heparin have been established from the Furth murine mastocytoma. The parental line (MST) divides in suspension every 14-18 h in growth medium supplemented with fetal bovine serum or defined growth factors. Adherent subclones were selected by adhesion to plastic culture vessels. Both adherent and nonadherent cells contain about 0.4 micrograms of glycosaminoglycan hexuronic acid per 10(6) cells, composed of 80% heparin and 20% chondroitin sulfate E. Deaminative cleavage of MST heparin by HNO2 at pH 1.5 released disaccharides that were similar in composition to those obtained from commercial heparin, except that disaccharides containing 3,6-O-desulfated GlcN units were not found. Greater than 90% of the glycosaminoglycans were stored in cytoplasmic granules, and challenge of the cells with dinitrophenylated bovine serum albumin and anti-dinitrophenyl IgE released a portion of the stored material. Growth studies of subclones showed that MST cells tolerate a 10-fold variation in glycosaminoglycan content. Incubation of cells with sodium chlorate reduced glycosaminoglycan sulfation by > 95% without affecting cell growth. Thus, granule glycosaminoglycans appear to be nonessential for growth of MST cells.

Animals↗
PubMed1992

The patA gene product, which contains a region similar to CheY of Escherichia coli, controls heterocyst pattern formation in the cyanobacterium Anabaena 7120.

In Anabaena 7120, heterocysts (cells specialized for nitrogen fixation) develop at the ends of filaments and at intervals within each filament. We have isolated a mutant Anabaena strain that develops heterocysts mostly at the ends of filaments. This mutant, PAT-1, grows poorly under nitrogen-fixing conditions. The wild-type gene that complements the mutation in PAT-1, called patA, was cloned and sequenced. The predicted PatA protein contains 379 amino acids distributed among three "domains" based on predictions of hydropathy and flexibility. The carboxyl-terminal domain is very similar to that of CheY and other response regulators in two-component regulatory systems in eubacteria. The patA mutation suppresses the multiheterocyst phenotype produced by extra copies of the wild-type hetR gene described previously, suggesting that PatA and HetR are components of the same environment-sensing regulatory circuit in Anabaena.

Amino Acid Sequence↗
PubMed1992

Mössbauer study of the native, reduced and substrate-reacted Desulfovibrio gigas aldehyde oxido-reductase.

The Desulfovibrio gigas aldehyde-oxido-reductase contains molybdenum and iron-sulfur clusters. Mössbauer spectroscopy was used to characterize the iron-sulfur clusters. Spectra of the enzyme in its oxidized, partially reduced and benzaldehyde-reacted states were recorded at different temperatures and applied magnetic fields. All the iron atoms in D. gigas aldehyde oxido-reductase are organized as [2Fe-2S] clusters. In the oxidized enzyme, the clusters are diamagnetic and exhibit a single quadrupole doublet with parameters (delta EQ = 0.62 +/- 0.02 mm/s and delta = 0.27 +/- 0.01 mm/s) typical for the [2Fe-2S]2+ state. Mössbauer spectra of the reduced clusters also show the characteristics of a [2Fe-2S]1+ cluster and can be explained by a spin-coupling model proposed for the [2Fe-2S] cluster where a high-spin ferrous ion (S = 2) is antiferromagnetically coupled to a high-spin ferric ion (S = 5/2) to form a S = 1/2 system. Two ferrous sites with different delta EQ values (3.42 mm/s and 2.93 mm/s at 85 K) are observed for the reduced enzyme, indicating the presence of two types of [2Fe-2S] clusters in the D. gigas enzyme. Taking this observation together with the re-evaluated value of iron content (3.5 +/- 0.1 Fe/molecule), it is concluded that, similar to other Mo-hydroxylases, the D. gigas aldehyde oxido-reductase also contains two spectroscopically distinguishable [2Fe-2S] clusters.

Aldehyde Oxidoreductases↗
PubMed1992

Impact of self-management education on the functional health status of older adults with heart disease.

This paper presents findings from the evaluation of a self-management education program based on self-regulation principles. Older men and women (N = 324) were randomly assigned to program and control groups. Outcomes were measured using the Sickness Impact Profile. Twelve months following baseline data collection, psychosocial functioning of program participants was significantly better than that of controls. Different program effects were noted when results were analyzed by participant gender.

Activities of Daily Living↗
PubMed1992

The structure of the Mental Health Inventory among Chinese in Taiwan.

This study attempted to ascertain the construct validity and external validity of the Mental Health Inventory in a Chinese population in Taiwan and contrast these results with results obtained from studies of several U.S. populations. In particular, a series of measurement models were specified and evaluated to address the issues of reliability and validity. Data were collected from personal interviews of a probability sample of 1,194 Chinese respondents 14 years of age and older in four townships in southwest Taiwan. The Mental Health Inventory was found to involve two major components: positive well-being and psychological distress. As a hierarchical structure, each component consists of one second-order and two or three first-order factors. The relationships between well-being and distress can be characterized as substantially independent and modestly bipolar depending on the level and specification.

Adolescent↗
PubMed1992

Characterization of a non-tissue-specific, 3',5'-cyclic adenosine monophosphate-responsive element in the proximal region of the rat prolactin gene.

The nature of a DNA element located in the -100 to -85 region of the rat PRL gene has been characterized. Previous studies demonstrated that this region may contribute to basal and hormonally regulated expression of the PRL gene. As this region contains a sequence with similarity to a consensus cAMP-responsive element (CRE), a possible role for the cAMP response element binding protein (CREB) has been explored. A point mutation which made the PRL CRE-like sequence less like a consensus CRE had little effect on basal or cAMP-stimulated expression of a PRL-luciferase reporter gene. DNase footprint studies demonstrated that the proximal region of the PRL gene does not contain a high affinity CREB binding site. Mobility shift experiments demonstrated that the major GH3 nuclear protein which interacts with the -100 to -85 region of the PRL gene in vitro is not CREB. Transfection of a dominant inhibitor of CREB action had little or no effect on expression of an indicator gene containing the PRL proximal region. Thus, the PRL proximal region does not contain a high affinity CREB binding site, and it is unlikely that CREB plays a major role in expression of the PRL gene. The functional capabilities of the -100 to -85 region of the PRL gene were then tested in a transfection assay. Synthetic multimers of this region were found to be sufficient to permit a transcriptional response to cAMP or TRH in GH3 cells and cAMP in Rat-1 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Social support among the aged in Wuhan, China.

"This study provides information on supportive social relations in a sample of 2,762 elderly people in Wuhan, China. The elderly concerned were found to be actively engaged in exchanges of social support with their families and kin. They not only receive assistance but also provide a substantial amount of help to others. These supportive ties were highly positive and satisfactory to the great majority of the respondents. Only moderate correlations were found among various dimensions of social support. These results underscore the multi-dimensional nature of social support and suggest that caution needs to be exercised in extrapolating interpersonal exchanges from social embeddedness."

Adult↗
PubMed1992

Cross-cultural variations in depressive symptoms in later life.

The purpose of this study is twofold: to estimate the prevalence of depressive symptoms among older adults in four culturally diverse groups (white Americans, black Americans, Japanese, Taiwanese), and to assess whether there are cross-cultural variations in the way depressive symptoms are manifest. Data from three recent nationwide surveys in the United States, Japan, and Taiwan reveal that the lowest overall levels of depressive symptoms are found among Japanese elderly, followed by Taiwanese, white Americans, and black Americans respectively. Based on previous cross-cultural research, it was hypothesized that the Japanese tend to express depressive symptoms as interpersonal complaints, whereas Taiwanese are more likely to manifest somatic symptoms. In contrast, Americans were expected to express depressive symptoms in the form of depressed cognitions. The findings failed to support these hypotheses. Instead, older Americans tended to have higher scores than Orientals on all three depressive symptom clusters.

Aged↗
PubMed1992

Quantitative evaluation of flicker ERG waveforms in low vision patients.

Flicker electroretinograms (FERGs) of 30Hz were recorded for 46 eyes (23 cases) of low vision, including 38 eyes with retinal diseases and 8 eyes with optic neuropathy, and for 39 normal eyes (33 cases). The recorded wave forms were analysed by two methods: (1) to measure the peak to peak amplitude and pseudophase directly, and (2) to measure the amplitude and phase of fundamental response component (30Hz) by discrete Fourier transform (DFT). The abnormality ratios between these two methods were compared in low vision patients. All the eyes with optic neuropathy showed normal flicker ERG, the abnormality ratios of directly measured amplitude and the amplitude by DFT were 60.9% in 28 eyes and 71.7% in 33 eyes with retinal diseases respectively, the difference being no statistically significant (P > 0.05), while the abnormality ratios of directly measured pseudo-phase and the phase by DFT were 60.9% in 28 eyes and 82.6% in 38 eyes with retinal diseases respectively, the difference being statistically significant (P < 0.05). These results suggest that FERGs are an objective way to test the retinal function, and DFT for flicker ERGs are more useful in quantitative evaluation of the retinal function.

Adolescent↗
PubMed1992

The spectral VEP in normal subjects and dichromats.

The spectral VEP in 13 normal subjects (25 eyes), four cases (8 eyes) of protanopes and 8 cases (15 eyes) of deuteranopes were tested. In normal subjects, the shortest latencies of N1, P1, N2 were in 560 nm and the greatest amplitudes of N1-P1 and P1-N2 were 560-570 nm, around which the latencies were delayed and the amplitudes were decreased as the wavelengths of stimulative light increased or decreased gradually. The spectral VEP pattern of deuteranopes was similar to the normal subjects. In the protanopes, the shorter latencies of N1,P1,N2 and greater amplitudes of N1-P1, P1-N2 appeared in 520-530 nm and 570 nm, forming the two-thoughs and two-peaks shapes, with the shortest latencies and the greatest amplitudes in 520-530 nm. There were statistically significant differences of amplitudes and/or latencies in some wavelengths between the protanopes and normals and between the deuteranopes and normals.

Adolescent↗
PubMed1992

[A software design for standard grayscale printout of China-made automatic static quantitative TBC visual field analyser].

A method of "TBC GRAPH" software design for standard grayscale printout of TBC static quantitative perimetry is introduced. The software is operated in IBM PC/XT or PC/AT compatible computer, using Chinese Character Disk Operating System (CCDOS) which has widespread users in China. Symbols were established by using CCDOS word--make function, and sectoral as well as symbolic matrix were made, which realized the standard grayscale printout. The software is recommended for use in ophthalmic clinic and education.

Humans↗
PubMed1992

[The variations of PRL, LH, FSH and testosterone in renal disease].

Blood PRL was measured with RIA in 22 males and 19 females with various degrees of renal insufficiency. At the same time, blood LH, FSH, testosterone were studied in all the male patients and 20 sex-age matched healthy subjects. The results showed that the levels of PRL and LH were increased, and the level of testosterone was decreased significantly in male uremic patients. There was a significant negative correlation between PRL and testosterone. All the above parameters were measured again 8-25 days after continuous ambulatory peritoneal dialysis (CAPD) therapy in 5 male uremic patients. The BUN and Cr levels decreased and the clinical manifestations of uremia improved, but the levels of PRL, LH, FSH and testosterone showed no significant changes. The mechanisms of these variations were discussed.

Adolescent↗
PubMed1991

Financial strain and psychological well-being among the American and Japanese elderly.

Research in the United States indicates that stressful life events may create psychological distress among older adults by eroding their sense of personal control and by diminishing their feelings of self-worth. The purpose of this study was twofold: (a) to replicate these findings with data provided by a recent nationwide survey of elderly people in the United States (N = 1,523) and (b) to compare these findings with results obtained from a nationwide survey of older adults in Japan (N = 1,517). The findings from both surveys are quite similar. The data indicate that financial strain tends to erode feelings of control and self-worth in both cultures, and the weakening of these personal resources in turn tends to increase depressive symptoms.

Adaptation, Psychological↗
PubMed1991

The structure of the OARS physical health measures.

This article proposes and evaluates two models for integrating self-reported health status measures for the elderly with dominant conceptualizations of physical health. Each model includes three dimensions of physical health: chronic illness, functional limitation, and self-rated health. In Model 1, the dimensions are linked in a causal framework, whereas in Model 2, a second-order factor, labeled physical health status, is hypothesized to account for the relationships among the three dimensions. Each model was tested with data gathered in Cleveland (N = 1,834) and Virginia (N = 2,146) using the Older Americans Resources and Services Multidimensional Functional Assessment Questionnaire (OARS MFAQ). Analyses were further replicated by randomly dividing each sample. Both models fit the data well; their utilities will depend on the way in which physical health is conceptualized and on the nature of the research question at hand.

Activities of Daily Living↗