Search PubMed⌕ Search

Biomedical subjects

J Liang

Publications and source records attributed to J Liang.

At least 253 records · Page 14Linked to original sources
PubMed1994

Role of central vasopressin in cardiovascular regulation: effect of dehydration and sex.

The present study was performed to evaluate the role of central vasopressin in cardiovascular regulation. First, a novel vasopressin V1 antagonist (OPC21268) was injected intracerebroventricularly in conscious rats. In water-deprived animals, the mean arterial blood pressure (MABP) and heart rate were significantly decreased compared with euhydrated control rats. There was, however, no significant difference in the concentration of vasopressin in the perfusate of cerebrospinal fluid between groups. Second, vasopressin was intracerebroventricularly injected in male and female homozygous Brattleboro rats. The increase in MABP was greater in males than in females. These results suggest that central vasopressin is involved in blood pressure regulation in pathophysiological states.

Animals↗
PubMed1994

Objective measurement of wave aberrations of the human eye with the use of a Hartmann-Shack wave-front sensor.

A Hartmann-Shack wave-front sensor is used to measure the wave aberrations of the human eye by sensing the wave front emerging from the eye produced by the retinal reflection of a focused light spot on the fovea. Since the test involves the measurements of the local slopes of the wave front, the actual wave front is reconstructed by the use of wave-front estimation with Zernike polynomials. From the estimated Zernike coefficients of the tested wave front the aberrations of the eye are evaluated. It is shown that with this method, using a Hartmann-Shack wave-front sensor, one can obtain a fast, precise, and objective measurement of the aberrations of the eye.

Adaptation, Ocular↗
PubMed1994

Pericardiocentesis and drainage by a silicon rubber line without echocardiographic guidance. Experience in 55 consecutive patients.

Pericardiocentesis and drainage with a silicon rubber line were performed safely in 55 patients via the subxiphoid (80 times) or apical (1 time) approach at the bedside without echocardiographic guidance. The subxiphoid approach, which is close to the posterior of the sternum or the costal cartilage with a small acute-angle (15-30 degrees) to the parietal pericardium in front of the right ventricle, can avoid injuring the heart, liver and lungs. A line with sideholes near the distal end, which provides convenient drainage and has better histocompatibility, can be kept in place for a long period of time (1-82 days). It was also convenient to inject air, drugs or fluid through the line. There were no procedure-related serious complications or deaths. Emergency drainage with the Seldinger technique, especially for small to moderate effusions, is safe and simple.

Catheters, Indwelling↗
PubMed1994

[Characteristics of ancient medical administration in China and its contemporary enliytenment].

This paper deals with the common characteristies, general rules and elementary clues for ancient medical administration before the Opium War. It also discusses the esternal influencing factors, background of its gain and loss. It mentions 7 aspects for the enlightment of modern administration, viz.; establishment of a united administrative system, setting up of medical curriculum, medical exchanges and medical development, establishment of patent drugs of individual materia medica, standardization of measurement system, the long-standing task of medical literature, prevention and treatment of epidemic through the effort of the mass.

China↗
PubMed1994

A study of spectral electroretinogram of color vision defects due to macular diseases.

Studies of spectral electroretinograms in central serous retinopathy (CSR) and hereditary macular degeneration (HMD) showed that the b-wave amplitudes of most wavelengths of CSR were significantly decreased as compared with normal controls, and those of HMD were obviously lower than the normal values. Patients of HMD with type-A color vision defects (CVD) had primarily a reduction of b-wave amplitudes in the full spectrum of 480-620 nm, and patients with type-I CVD a reduction of b-wave amplitudes wave-lengths of 480-560 nm. These differences might reflect differences in damages to the medium-and long-wave length.

Adolescent↗
PubMed1994

[Study on phagocytosis of human neutrophils in diabetics].

Infection is one of the most common complications in diabetes mellitus (DM). The neutrophil plays an important role in the anti-infection mechanism. A comparative study on phagocytosis of P. Aeruginosa by human neutrophils in diabetic patients and healthy volunteers was carried out by means of the monolayer of neutrophils and ultrastructural observation in electronic microscopy. The results showed that the rates of phagocytosis, index of phagocytosis and rates of microbe lysis in DM group were much lower than those in normal controls (P < 0.01). The ultrastructure of neutrophils in diabetic patients became apparently abnormal during the process of neutrophil phagocytosis. The results demonstrated that the impairment in phagocytosis of neutrophils may be one of the causes of severe and repeated infection in diabetics.

Aged↗
PubMed1994

Evaluating diffusion of light in the eye by objective means.

PURPOSE: The authors have developed an index of diffusion that describes the relative spread of light inside and outside the region of image focus of the living human eye. It provides in numerical terms a measure of light scatter and can be used to characterize the optical deficit in eyes with age- and disease-related abnormalities of the anterior segment. METHOD: An improved version of the double-pass method of examining the aerial image formed by reflection of the retinal image of a point source is employed, together with a new way of analyzing the image. Experimental estimation shows the contaminating effect of back scatter from the media and corneal reflection to be negligible. Measurements are objective and do not require any responses on the part of the patient. Data become available practically on-line. RESULTS: Index of diffusion values were obtained on 13 patients and varied from 0.22 to 1.04, strongly tending to increase with age. They are rather robust to pupil size, exposure duration, and small amounts of defocus. CONCLUSION: The index appears to provide a promising measure of optical performance of the media of the anterior segment of the eye, which might be useful in studying the effect of aging, injury, and disease.

Adult↗
PubMed1994

The ear in the acquired immunodeficiency syndrome: I. Temporal bone histopathologic study.

A postmortem histopathologic investigation of temporal bones of patients with the acquired immunodeficiency syndrome (AIDS) was performed after microslicing, acid decalcification of the slices and paraffin embedding. Histopathologic changes in 49 temporal bones from 25 patients included severe otitis media in five patients (20%), low-grade otitis media in fifteen (60%), labyrinthine cryptococcosis in two, Kaposi's sarcoma deposit in the eighth nerve of one, and cytomegalovirus (CMV) inclusion-bearing cells in the inner and middle ear of six (24%). It was possible to identify the CMV genome by in situ hybridization in only two bones and expression of CMV antigen by immunohistochemistry in none, probably because of prolonged decalcification in acid. The ear is no less susceptible to AIDS-associated diseases than any other organ, and is particularly prone to CMV infection.

AIDS-Related Opportunistic Infections↗
PubMed1993

Metarhodopsin intermediates of the gecko cone pigment P521.

Cone visual pigments are responsible for color vision. Using low-temperature spectroscopy and linear/logarithmic time scale flash photolysis, we studied the photochemistry of the cone visual pigment P521 from the lizard Gekko gekko. We found both meta I and meta II intermediates in this cone pigment; meta I absorbs at 480 nm, and meta II absorbs at ca. 380 nm. The formation of meta I is a fast process with a lifetime of 2.8 microseconds for the slow component (pH 6.70, 8.0 degrees C, 2% digitonin) compared to 2.1 microseconds for bovine rhodopsin under these conditions. The formation of meta II does not have single-exponential kinetics but can be better characterized by fast and slow components. High pH favors faster kinetics of meta II formation, but less is formed. The amount of meta II formed has a pKa of 8.7. The fast component of the meta II formation seems to have a somewhat lower pKa (e.g., 6.4). Temperature also affects meta II formation, with high temperature favoring a faster rate and larger amounts. The higher pKa of the meta I to meta II transition in gecko P521 compared to a rod pigment like bovine rhodopsin (pKa = 6.4) probably is due to a cysteine residue at position 211 in gecko rather than a histidine residue in bovine rhodopsin.

Animals↗
PubMed1993

Cholesterol gallstone induction in hamsters reflects strain differences in plasma lipoproteins and bile acid profiles.

Because different strains of hamsters vary in their susceptibility to gallstones, the relationship between plasma lipoproteins, hepatic cholesterol, bile lipids and bile acid profile was examined during gallstone induction in strains of male Syrian hamsters from Charles River Lakeview (CHR), Biobreeder F1B (BIO) and Harlan Sprague-Dawley (HAR). Gallstones were induced by feeding a purified diet containing 0.4 or 0.8% cholesterol for 5 wk. Basal plasma total cholesterol was similar, but the hypercholesterolemia induced by dietary challenge was significantly lower in CHR than in HAR and BIO hamsters. Cholesterol-fed CHR hamsters transported cholesterol mainly in HDL (47%), whereas VLDL-C + IDL-C predominated in BIO and HAR hamsters, and their HDL transported only 28 and 38%, respectively. HAR hamsters accumulated the most hepatic cholesterol, revealed the highest cholate/cheno ratio, the lowest glycine/taurine ratio and hydrophobicity index. HAR also developed the fewest cholesterol gallstones (23%), while 64% of CHR and 58% of BIO hamsters had cholesterol gallstones and 34% of BIO hamsters developed pigment stones. Doubling dietary cholesterol from 0.4 to 0.8% doubled the incidence of cholesterol gallstones but exerted minimal impact on other parameters compared to strain differences. Thus, different strains of hamsters vary considerably with respect to biliary cholesterol, bile acid profile and formation of cholesterol gallstones associated with differences in plasma lipoprotein profiles.

Animals↗
PubMed1993

Changes in venous capacitance during prostaglandin E1-induced hypotension; comparisons with trinitroglycerin.

The purpose of this study was to examine the effects of prostaglandin E1 (PGE1) on venous capacitance during controlled hypotension. Trinitroglycerin (TNG) was used as a control agent. In rats anesthetized with ketamine, mean arterial pressure was lowered to 70 mmHg and subsequently 50 mmHg by intravenous infusion of PGE1 or TNG. Venous capacitance was assessed before and during induced hypotension by measuring the mean circulatory filling pressure (MCFP). MCFP was measured after briefly arresting the circulation by inflating an indwelling balloon in the right atrium. MCFP was significantly decreased by PGE1 from 7.9 +/- 0.3 to 6.9 +/- 0.3 mmHg at mean arterial pressure of 70 mmHg and to 6.9 +/- 0.2 mmHg at mean arterial pressure of 50 mmHg. The decrease in MCFP by PGE1 at mean arterial pressure of 70 mmHg was not significantly different from TNG. However, the decrease in MCFP by PGE1 at mean arterial pressure of 50 mmHg was significantly less than that by TNG. The results suggest that the venous capacitance may be increased by PGE1 to a similar degree with TNG at doses to produce a comparable level of moderate hypotension, but the increase in venous capacitance may be less in PGE1 than TNG at doses to produce deep hypotension.

Journal Article↗
PubMed1993

Stress and exercise among the Japanese elderly.

This study seeks to replicate and extend research on the stress process by examining the relationships among stress, social support, physical exercise, and depressive symptoms with data provided by a recent nationwide survey of older adults in Japan. The findings reveal that more frequent physical exercise is associated with less psychological distress. Moreover, the data suggest that some (but not all) types of stressors tend to diminish the frequency of physical activity. Finally, and perhaps most important, the results reveal that social support tends to promote more frequent exercise. This can occur in two ways. First, more emotional support was related to better exercise habits. In addition, negative interaction was also associated with more frequent exercise, suggesting that informal social sanctions can foster positive health behaviors.

Aged↗
PubMed1993

Plasma lipoproteins, biliary lipids and bile acid profile differ in various strains of Syrian hamsters Mesocricetus auratus.

1. Plasma and biliary lipids were assessed in four strains of Syrian hamsters [Charles River Lakeview, (CHR), Biobreeder F1B (BIO), Harlan Sprague-Dawley (HAR) and Sasco (SAS)] fed a cholesterol-free diet. 2. Plasma cholesterol differed with SAS > CHR > HAR > BIO. 3. BIO Hamsters had the lowest HDL and highest VLDL + LDL/HDL ratio, but their biliary secretion of bile acids, phospholipids and cholesterol was 50% lower than other hamsters. 4. Chenodeoxycholate was highest in CHR and the cholate:cheno ratio depressed in CHR hamsters. 5. CHR hamsters had the highest lithogenic index and cholesterol-saturated bile.

Adipose Tissue↗
PubMed1993

Two new taxane diterpenoids from Taxus mairei.

Two new taxane diterpenoids were isolated from the heartwood of Taxus mairei and identified as 5 alpha, 7 beta, 9 alpha, 10 beta, 13 alpha-pentaacetoxy-2 alpha-benzoyloxy-4 alpha, 20-dihydroxytax-11-ene [2] and 7 beta, 9 alpha, 10 beta, 13 alpha, 20-pentaacetoxy-2 alpha-benzoyloxy-4 alpha, 5 alpha-dihydroxytax-11-ene[3]. The structures of 2 and 3 were determined primarily on the basis of analysis of their 1H-nmr, 13C-nmr, 1H-1H 2D COSY, 1H-13C 2D COSY, DEPT, and mass spectra. This is the first report of naturally occurring taxoids lacking a D ring but oxygenated at the 4, 5, and 20 positions.

Diterpenes↗
PubMed1993

Stress, social support, and psychological distress among the Chinese elderly.

This study examined the relationships among stress, social support, and depressive symptoms with data provided by a large representative sample (N = 2,721) of older adults who live in the People's Republic of China. Many Western investigators believe that elderly people respond to stressful experiences by mobilizing assistance from their significant others. However, recent American studies suggest that this may not always be true, and that when certain stressors arise, older adults may actually receive less support from significant others. The purpose of our study was to evaluate these competing views in a culturally diverse setting. The findings reveal that both perspectives have something to offer and that financial strain (i.e., one kind of stressor) may increase some kinds of assistance (i.e., economic support) at the same time that it erodes other types of support (e.g., emotional support).

Aged↗
PubMed1993

Structure and origin of middle ear corpuscles.

The incidence, origin, structure and composition of middle ear corpuscles (MEC) were studied by dissection microscopy, by special stains and immunocytochemistry of histological sections and by transmission electron microscopy. MEC are formed within fibrous bands derived from transparent fibrous sheets which appear mainly in the mastoid antrum in the middle-aged and elderly. MEC are covered by a layer of epithelial cells with a normal basal lamina, and are largely composed of concentric layers of collagen which display alternating positive and negative birefringence. Pulmonary and prostatic corpora amylacea show a similar light microscopical structure and age relationship, but contain amyloid. It is suggested that MEC and the other bodies may be organized foci of epithelial basement membrane expansion perhaps derived from an in vivo counterpart of the "domes' seen in vitro in some monolayer epithelial cultures.

Adult↗
PubMed1993

The patB gene product, required for growth of the cyanobacterium Anabaena sp. strain PCC 7120 under nitrogen-limiting conditions, contains ferredoxin and helix-turn-helix domains.

A mutant of Anabaena sp. strain PCC 7120, called PAT-2, that grows poorly under nitrogen-fixing conditions, has been isolated. The heterocysts of the mutant strain develop much more slowly than those of the wild type and are spaced more closely in an older culture of the mutant than in the wild type. The wild-type gene that complements the mutation in PAT-2, called patB, was isolated and characterized. The predicted 529-amino-acid PatB protein contains a region very similar to the Fe4S4 bacterial-type ferredoxins near its N terminus and a helix-turn-helix motif near its C terminus. This pattern of domains resembles those of transcriptional regulators in both prokaryotes and eukaryotes. The mutation in strain PAT-2 is the deletion of G at nucleotide 1342 in the patB gene, resulting in the loss of a 62-amino-acid fragment from the C terminus of the PatB protein, including the helix-turn-helix motif.

Amino Acid Sequence↗