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Biomedical subjects

M Wei

Publications and source records attributed to M Wei.

At least 109 records · Page 6Linked to original sources
PubMed1995

The impact of changes in coffee consumption on serum cholesterol.

To investigate the possible association between changes in coffee consumption and serum cholesterol levels, information was obtained from 2109 healthy nonsmokers aged 25-65 years at two clinic visits to a preventive medical center between 1987 and 1991 (mean interval between visits: 16.7 months). After adjusting for age and changes in other potential confounders, about 2 mg/dl total cholesterol increase was associated with an increase of one cup of regular coffee per day (p < 0.001). A dose-response was found among those who decreased regular coffee consumption, those who continued the same dose, and those who increased consumption. The same trend was observed among those who quit drinking regular coffee, those who never drank coffee, and those who started to drink coffee. No change in cholesterol level was found among those continuing to consume the same quantity of regular coffee compared to those who never drank coffee. The change in cholesterol level was not related to consumption of decaffeinated coffee, regular tea, decaffeinated tea, or cola with caffeine. To our knowledge, this is the first follow-up study correlating change in coffee consumption with change in serum cholesterol in a large group of men and women.

Adult↗
PubMed1995

Genetic correlation and heritabilities for purebred and crossbred performance in poultry egg production traits.

Genetic correlations between purebred and crossbred performance and purebred and crossbred heritabilities were estimated for egg production traits of laying chickens using a multivariate sire model accounting for additive relationships between sires. Two sire lines, denoted lines 1 and 2, were crossed to one dam line to produce crossbred progeny. Records for egg weight, egg specific gravity, and egg number were collected on purebred and crossbred hens. In total, 99 sires in line 1 and 292 sires in line 2 were used in the analysis, each sire producing on average 45 purebred and 105 crossbred daughters. Estimates of purebred heritability in lines 1 and 2 were in range of .54 to .74 for egg number traits, .52 to .91 for egg weight traits, and .41 to .83 for egg specific gravity traits. Estimates of crossbred heritability were .04 to .51 for egg numbers, .23 to .45 for egg weight, and .13 to .31 for egg specific gravity. The sire component in crossbreds differed up to 78% from the sire component in purebreds depending on traits. The estimate of genetic correlation (rpc) between purebred and crossbred performance was .56 to .73 for egg number, .69 to .99 for egg weight, and .72 to .82 for egg specific gravity. Although crossbred parameters were strongly affected by environmental factors, the results tend to agree with the theory that traits with a larger dominance variation and a larger difference between sire components in purebreds and crossbreds show a lower rpc.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Synthesis, solution structure and biological action of PACAP-related peptide.

High quality PACAP-related peptide (PRP), a 29 amino-acid region of the PACAP precursor protein, has been synthesized in quantities sufficient for biological and structural studies. PRP has a distinct biological activity on the gallbladder that is similar to PACAP, but opposite to that of VIP and its related peptide, PHM. Its solution structure has been investigated by circular dichroism spectroscopy and 2D 1H nuclear magnetic resonance spectroscopy. In contrast to the poorly defined structure in aqueous solution alone, the limiting structure, under conditions that mimic a membrane-like environment, possesses stable secondary structure with a helical region between residues 3 and 20, that is terminated by the presence of glycine at residue 21 and is followed by a region of nascent helix. The similarities and differences in the structure of PRP, PACAP27 and GHRH(1-29) are made through comparison of their H alpha chemical shift data and differences in their biological activities assessed.

Amino Acid Sequence↗
PubMed1994

Total cholesterol and high density lipoprotein cholesterol as important predictors of erectile dysfunction.

Although erectile dysfunction is frequently seen in patients with manifestations of arteriosclerotic disease, the independent contribution of serum cholesterol in predicting erectile dysfunction is unclear. The aim of this study was to examine the relation between serum cholesterol and erectile dysfunction. Medical histories, physical examinations, and blood tests were obtained at Cooper Clinic, Dallas, Texas, from 3,250 men aged 26-83 years (mean, 51 years) without erectile dysfunction at their first visit, who had one more clinic visit, all between 1987 and 1991. These men were followed 6-48 months after the first clinic visit (mean, 22 months). Erectile dysfunction was reported in 71 men (2.2%) during follow-up. Every mmol/liter of increase in total cholesterol was associated with 1.32 times the risk of erectile dysfunction (95% confidence interval 1.04-1.68), while every mmol/liter of increase in high density lipoprotein cholesterol was associated with 0.38 times the risk (95% confidence interval 0.18-0.80). Men with a high density lipoprotein cholesterol measurement over 1.55 mmol/liter (60 mg/dl) had 0.30 times the risk (95% confidence interval 0.09-1.03) as did men with less than 0.78 mmol/liter (30 mg/dl). Men with total cholesterol over 6.21 mmol/liter (240 mg/dl) had 1.83 times the risk (95% confidence interval 1.00-3.37) as did men with less than 4.65 mmol/liter (180 mg/dl). Those differences remained essentially unchanged after adjustment for other potential confounders. The authors conclude that a high level of total cholesterol and a low level of high density lipoprotein cholesterol are important risk factors for erectile dysfunction.

Adult↗
PubMed1994

[Electrophysiological investigation on decussate communication of bulbospinal inspiratory neurons with phrenic nucleus at level of spinal cord].

The experiments were carried out on anesthetized, vagotomized, immobilized and artificially ventilated cats, rabbits and rats. The rhythmic respiratory activities on both sides of the phrenic nerves existed after a hemisection between the 2nd and 3rd cervical cord, while the activities of the phrenic nerve ipsilateral to the hemisection disappeared following a subsequent mid-sagittal section from the 3rd to 5th cervical cord. The amplitude of the phrenic activities on either side was lowered, more remarkably on the ipsilateral side, by the hemisection. These results indicate that there exists a decussate communication of the bulbospinal inspiratory neurons with the phrenic nucleus at the level of spinal cord. In other words, the phrenic nucleus receives inspiratory drives via descending pathways on both sides of the cervical cord, mainly on the ipsilateral side.

Animals↗
PubMed1994

[Effects of shenyan yiqiye on experimental membranous glomerulonephritis in rabbits].

The cationic bovine serum albumin (C-BSA) was used for duplicating experimental animal model of membranous glomerulonephritis with chronic renal failure. Shenyan Yiqiye (SYYQY) was adopted for treatment. The results showed that, in the therapeutic group, the urine protein and serum creatinine were reduced as compared with those in pathological group, P < 0.01. The parameter of morphometric analysis of glomeruli such as mean diameter, mean perimeter, mean surface area, mean volume, mean cross sectional area were all decreased, P < 0.01, the number of glomerular proliferative cells and thickness of glomerular capillary wall were all attenuated, P < 0.01, as compared with those in the pathological group. It suggested that SYYQY might alleviate the glomeruli lesions and benefit the renal functions.

Animals↗
PubMed1993

Intracellular transport of class I MHC molecules in antigen processing mutant cell lines.

Intracellular transport and stability of class I MHC glycoproteins depends on the assembly of H chain, beta 2-microglobulin, and peptide. The Ag processing mutant cell lines T2 and RMA-S have defects in peptide loading of class I, resulting in reduced cell surface expression of class I molecules. Expression of class I molecules in the murine cell line RMA-S can be induced at 26 degrees C, suggesting that they are transported to the cell surface, but are unstable. However, most human class I molecules in T2 are poorly expressed at the cell surface, even at 26 degrees C. To directly compare the transport of human and mouse alleles in RMA-S and T2, the human alleles HLA-A2, A3, and B27 were transfected into RMA-S along with human beta 2-microglobulin, and the mouse alleles H-2Kb and Db were transfected into T2. Surface expression of HLA-A3 and B27 in RMA-S remained less than 10% of wild-type levels at 26 degrees C. H-2Kb and Db in both cell lines, however, were expressed at 20 to 30% wild-type levels at 37 degrees C and could be induced to wild-type levels at 26 degrees C or with peptides. The selective expression of murine class I glycoproteins at the cell surface of T2 is not because of their greater stability when associated with human beta 2m, since H-2Kb and Db H chain/human beta 2m complexes dissociate more rapidly in vitro than HLA-A3 and B27 complexes. These results suggest that the difference in transport between human and mouse class I in T2 reflects a fundamental structural property of the class I glycoproteins.

Alleles↗
PubMed1993

Altered cerebrovascular responsiveness to N-methyl-D-aspartate after asphyxia in piglets.

We examined effects of prior asphyxia and reventilation on pial arteriolar responses to arterial hypercapnia, topical application of forskolin, and topical application of N-methyl-D-aspartate (NMDA) in newborn pigs. Piglets were anesthetized and ventilated with a respirator. Pial arteriolar diameter was determined using a closed cranial window and intravital microscopy. After baseline diameter was determined, the respirator was turned off for 10 min. Then the respirator was turned on, and the piglet was ventilated for 4 h. At 1, 2, and 4 h after asphyxia, arteriolar diameter was determined during control conditions and during arterial hypercapnia (inspiration of 10% CO2 in air; n = 4), topical application of 2.4 x 10(-8) M forskolin (n = 6), and topical application of 10(-5) M NMDA (n = 6). At 1 h after asphyxia, arterial hypercapnia dilated pial arterioles by 39 +/- 3%, topical forskolin dilated pial arterioles by 24 +/- 3%, and NMDA dilated pial arterioles by 10 +/- 1%. For arterial hypercapnia and forskolin application, arteriolar responses were not different from 1 h at 2 and 4 h postasphyxia. In contrast, for NMDA, arteriolar responses were greater at 2 h (23 +/- 6%) and 4 h (30 +/- 5%) than at 1 h. In time-control animals, NMDA dilated arterioles by 20 +/- 5% at 1 h, by 24 +/- 8% at 2 h, and by 21 +/- 4% at 4 h (n = 5). Indomethacin administration (5 mg/kg iv) before asphyxia resulted in a 23 +/- 3% arteriolar dilation in response to NMDA at 1 h (n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Animal model estimation of additive and dominance variances in egg production traits of poultry.

An animal model analysis was used to estimate simultaneously additive (sigma 2a) and dominance (sigma 2d) variances for egg production traits within three White Leghorn lines. The data consisted of information for three generations on egg number (EN) produced at 18 to 25 (EN1), 26 to 65 (EN2), and 18 to 65 wk of age (EN3); egg weight (EW) measured at 30 to 35 (EW1) and 40 to 45 wk (EW2); and egg specific gravity (ESG) measured at 30 to 35 (ESG1) and 40 to 45 wk (ESG2). A transformation was used for EN2 and EN3 because of a skewed distribution. In total, 813 sires, 2,575 dams, and 28,649 daughters were involved in the analyses. Three genetic models (sire-dam, additive, and dominance) were compared in estimating heritability (h2). The sire-dam model underestimated h2 because it ignored animal relationships. The h2 estimates from the additive model were approximately 9 to 52% higher for EN and 2 to 18% higher for EW and ESG than those from the dominance model. The differences between the h2 estimates from the additive and dominance models were increased for larger dominance variance sigma 2d. Ratios of sigma 2d to total variance were high for EN (10 to 20%) and low for EW and ESG (1 to 13%). Ratios of sigma 2d to total genetic variance for EN1, EN2, EN3, EW1, EW2, ESG1, and ESG2 were 18 to 36, 29 to 43, 29 to 56, 1 to 26, 3 to 8, 20 to 27, and 2 to 14%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[The effect of ventricular pacing on plasma atrial natriuretic factor levels and its clinical significance].

The effects of increasing pacing rate on cardiac hemodynamics and the release of atrial natriuretic factor (ANF), cGMP and cAMP were studied in 21 patients underwent ventricular pacing. ANF levels elevated insignificantly in patients without VA conduction, but elevated significantly in patients with VA conduction at pacing rate of 90,110 and 160 beat/min. The intracardiac pressure between these two groups of patients did not show significant difference. The conclusions are: (1) elevation of ANF levels at increasing pacing rate is mainly due to atrial distension rather than atrial pressure per se. (2) The elevation of ANF levels may reflect the changes of hemodynamics, the higher the ANF level, the more increase in intracardiac pressure. (3) marked elevation of ANF level may suggest presence of VA conduction in patients during ventricular pacing.

Adult↗