Search PubMed⌕ Search

Biomedical subjects

M Sun

Publications and source records attributed to M Sun.

At least 199 records · Page 11Linked to original sources
PubMed1996

Nutrition in minority elders: current problems and future directions.

Nutrition and aging are inseparably connected as eating patterns affect the progress of many degenerative diseases associated with aging. In turn, the nutritional status of the elderly, particularly minority elders (the most rapidly growing segment of the population in the United States), may be adversely affected by a number of factors associated either directly or indirectly with aging. Because reducing morbidity through health promotion and disease prevention could both improve the quality of elderly life and lessen the burden on the health care system, it would seem reasonable that such efforts, including nutrition education, in minority elderly would be of benefit. The extent of the potential value of such preventive programs, however, remains uncertain, and the task of determining nutrient needs of the elderly difficult. Special studies are required to describe the association of nutrition-related factors with chronic diseases, particularly those prevalent in minority elders.

Age Factors↗
PubMed1996

Immunohistochemical localization of the glucocorticoid receptor in human fetal membranes and decidua at term and preterm delivery.

The human fetal membranes and decidua may be important in the onset and/or progression of human labor by providing prostaglandins for this process. Glucocorticoids have been implicated in the regulation of prostaglandin production by these tissues but to date there is no direct evidence for glucocorticoid receptors (GRs) being present in human intrauterine tissues. The purpose of the present study was to determine, using immunohistochemistry, whether the human fetal membranes and decidua contained GRs; to determine the localization of receptors to the cytoplasm or nuclei, and to examine the content and distribution of the GRs in tissues obtained during pregnancy following preterm labor (< 37 weeks) and at term prior to and following term labor. Term tissues were obtained prior to labor by elective Caesarean section (n = 9) or following vaginal delivery (n = 9). Tissues from 14 patients who delivered preterm but with no clinical evidence of infection were also examined. Cryostat sections were thaw-mounted onto microscope slides. The immunoreactive GRs were visualized with an Elite Vectastain ABC Kit using a polyclonal antibody prepared against a synthetic peptide corresponding to amino acids 346-367 of the human GR. At term, nuclear GRs were found in amnion epithelial cells, mesenchyme and the chorion laeve. GRs were present, but were less defined, in the decidua. A similar distribution was found in the preterm tissues. However, nuclear staining in the amnion epithelial cells, mesenchymal cells, chorion and decidua was more pronounced in tissues obtained following preterm labor. This study provides direct evidence for the presence of GRs in human fetal membranes and decidua, and suggests the possible importance of multiple cell types in the action of glucocorticoids in these tissues.

Amnion↗
PubMed1996

Localization of prostaglandin H synthase type 2 protein and mRNA in term human fetal membranes and decidua.

Prostaglandin (PG) production by human fetal membranes (amnion and chorion laeve) may be important in the onset and progression of labour, cervical ripening and membrane rupture. Prostaglandin H synthase (PGHS) is a key enzyme in PG formation and has two isoforms, a constitutive form (PGHS-1) and an inducible form (PGHS-2). The present study examined the cellular distribution of the PGHS-2 enzyme and PGHS-2 mRNA in term human fetal membranes and decidua prior to and following labour, using immunohistochemistry and in situ hybridization with an 35S-labelled oligonucleotide probe. The PGHS-2 protein was found to be localized in amnion epithelial cells and chorion laeve trophoblast, but was absent or at low levels in the decidual stroma in most tissues, although cells surrounding some of the blood vessels in the decidual did express PGHS-2. In situ hybridization demonstrated that PGHS-2 mRNA had a similar distribution and was localized to amnion epithelial cells, cells in the amnion-chorion mesenchyme, chorion laeve trophoblast and, occasionally, to cells surrounding blood vessels in the decidua. Of particular note was the high mRNA expression in some cells and low expression in other cells, particularly in the chorion, and the low level of PGHS-2 mRNA in decidua. There was no observable difference in the cellular localization of PGHS-2 protein or PGHS-2 mRNA in tissues obtained prior to and following labour. The studies indicate that, at term, the inducible form of PGHS, PGHS-2, is expressed at a high level in fetal tissues in a number of different cell types rather than in the maternal decidua.

Base Sequence↗
PubMed1996

Increased energy expenditure in hemodialysis patients.

Malnutrition is prevalent in chronic hemodialysis patients and is related to multiple factors; the hemodialysis procedure itself has been suggested as a catabolic factor. To examine the possible role of hemodialysis on energy metabolism, resting energy expenditure and respiratory quotient in ten chronic hemodialysis patients was measured in this study, using a whole-room indirect calorimeter. Measurements were done continuously: for 2 h before hemodialysis, during 4 h of hemodialysis, for 2 h after hemodialysis, and separately on a nondialysis day after 12 h of fasting. Age-, sex-, and body mass index-matched healthy volunteers were used as control subjects. Chronic hemodialysis patients have a significantly higher resting energy expenditure on a nondialysis day (1.18 +/- 0.15 kcal/min; P < 0.01) as compared with control subjects (1.10 +/- 0.16 kcal/ min). Resting energy expenditure further increased significantly during the hemodialysis procedure (1.32 +/- 0.18 kcal/min, averaged over the 4 h of hemodialysis; P < 0.01 versus predialysis) and was also significantly higher compared with the postdialysis period and nondialysis day resting energy expenditure (P < 0.001 for both). This effect was most pronounced during the first (1.37 +/- 0.19 kcal/min) and second (1.33 +/- 0.18 kcal/min) hours of hemodialysis (P < 0.001 for both). Respiratory quotient was not significantly affected by hemodialysis. It was concluded that chronic hemodialysis patients have higher than normal resting energy expenditure levels, which is further increased during hemodialysis. This process may significantly potentiate the protein-calorie malnutrition seen in this patient population.

Adult↗
PubMed1996

Energy expenditure, television viewing and obesity.

OBJECTIVE: To measure energy expenditure (EE) of television viewing, sitting, and resting and duration of self-selected television viewing in obese and non-obese men and women. DESIGN: Cross-over randomized study consisting of two separate 24-h stays in a whole-room indirect calorimeter. SUBJECTS: 123 obese and non-obese healthy men and women (age: 38 +/- 9, BMI: 29.4 +/- 7.9) MEASUREMENTS: Rates of energy expenditure during resting (RMR), sitting (EEsit) and television viewing (EEtv) using indirect calorimetry technique on two separate 24-h stays in a whole-room indirect calorimeter. Physical activities and work of body movements during these periods using a large force platform system located inside the calorimeter. RESULTS: Rates of EE for television viewing, adjusted for differences in body composition were 18% higher than resting metabolic rate (RMR), but similar to rates of other sedentary activities. There were no significant differences between obese and non-obese subjects in metabolic rates during resting, television viewing, and other sedentary activities. Average time of self-selected television viewing was significantly greater in obese than in non-obese subjects and also in women than in men. CONCLUSION: EE rate for television viewing in adults is higher than RMR and similar to other sedentary activities. Obese adults choose television viewing as a form of leisure activity more often than non-obese individuals and as a result they could significantly reduce other forms of physical activities and total daily EE.

Adult↗
PubMed1996

Adenocarcinomas of the esophagus and gastric cardia: medical conditions, tobacco, alcohol, and socioeconomic factors.

Adenocarcinomas of the esophagus and gastric cardia have increased in incidence over the past 10-15 years in Western countries. The cause for this increase in incidence is still unknown. Our study was designed to investigate potential risk factors for adenocarcinomas of the esophagus and gastric cardia and to compare the risk profiles of a group of patients with this cancer with those having distal stomach cancer. We studied 95 incident cases with the pathological diagnosis of adenocarcinomas of the esophagus and gastric cardia, 67 patients with adenocarcinomas of the distal stomach, and 132 cancerfree controls. Patients were seen at Memorial Sloan-Kettering Cancer Center from November 1, 1992 to November 1, 1994. Epidemiological data were collected by a modified National Cancer Institute Health Habits History Questionnaire. Risk factors were analyzed using Mantel-Haenszel methods and a logistic regression model. Hypertension was associated with a 2-fold increased risk of adenocarcinomas of esophagus and gastric cardia after controlling for age, sex, race, education, pack-years of smoking, alcohol use, body mass index, and total dietary intake of calories. Increased risk of adenocarcinomas of esophagus and gastric cardia was associated with age, male gender, and Caucasian race. Tobacco smoking was related to a modest risk of adenocarcinomas of esophagus and gastric cardia. In contrast, the risk of distal stomach cancer was associated with stomach ulcers and pack-years of cigarette smoking. Iron deficiency was significantly associated with increased risk of both adenocarcinomas of the esophagus and gastric cardia and adenocarcinomas of the distal stomach. No obvious associations were identified for occupational exposures, family history of cancer, and physical activities. This study suggests that medical conditions such as hypertension and iron deficiency may be related to the risk of adenocarcinomas of esophagus and gastric cardia and confirms the moderate risk associated with tobacco smoking. Our results indicated an etiological heterogeneity with respect to risk factors identified between adenocarcinomas of esophagus and gastric cardia and those of the distal stomach.

Adenocarcinoma↗
PubMed1996

Effect of low-concentration CO2 on stereoacuity and energy expenditure.

BACKGROUND: Low-concentration CO2 commonly exists in our living environment in such locations as airplanes and cars. Its effect on visual performance and energy metabolism (through O2 uptake) has not been well studied, although several studies have shown that high-level CO2 (6-10%) significantly impaired visual performance. HYPOTHESIS: We felt that breathing CO2 might also interfere with the energy expenditure pathway, partly due to the reduced O2 fraction. Thus, we studied the effect of low-concentration CO2 (2.5%) on human visual stereoacuity and energy expenditure. METHODS: Computer-controlled Random Dot Stereograms and psychometric function were used for stereoacuity tests. A whole-room indirect calorimeter allowed for the accurate measurement of energy expenditure, and also served as a good testing environment. RESULTS: Of 10 subjects tested, 8 had a slight increase in resting energy expenditure after exposure to 2.5% CO2. The increase ranged from 0.4-6.1% (p = 0.087, paired t-test). In stereoacuity tests, the psychometric function curves of all three subjects tested shifted to the right when breathing 2.5% CO2 and returned to baseline 2 h after breathing fresh air. Stereoacuity value, which is the reciprocal of stereoscopic threshold, was significantly lower (p < 0.01, 2-tailed z score test) after CO2 exposure for all subjects tested. CONCLUSION: We conclude that CO2 levels as low as 2.5% can cause temporary reduction in human stereoacuity, and also cause a persistent but small increase in energy expenditure.

Adult↗
PubMed1996

Long-term blood pressure control in older Chinese patients with isolated systolic hypertension: a progress report on the Syst-China trial.

This report on the ongoing double-blind placebo-controlled Syst-China trial investigated whether antihypertensive drug treatment based mainly on a calcium entry blocker and a converting enzyme inhibitor, would be suitable for maintaining long-term blood pressure (BP) control in older Chinese patients (average age: 67 years) with isolated systolic hypertension (systolic pressure 160-219 mm Hg and diastolic pressure < 95 mm Hg). Active treatment consisted of nitrendipine (10- 40 mg/day) with the possible addition of captopril (12.5- 50 mg/day) and hydrochlorothiazide (12.5-50 mg/day), as necessary to reduce systolic pressure to a level of 150 mm Hg or lower and by at least 20 mm Hg. Matching placebos were used in the control group. This progress analysis was restricted to BP control up to 3 years of follow-up. The placebo (n = 1134) and active treatment n = 1245) groups had similar characteristics at enrolment. The sitting BP averaged 170/86 mm Hg. Systolic pressure fell (P < 0.001) on average 8 mm Hg more on active treatment than on placebo and diastolic pressure 3 mm Hg more. Fewer patients remained on monotherapy in the placebo than in the active treatment group (P < 0.001); on placebo the second and third line medications were started more frequently (P < 0.001). This progress report showed that significant BP reduction can be achieved and maintained in older Chinese patients treated with a calcium antagonist, associated with a converting-enzyme inhibitor and a thiazide, as necessary. Whether this BP reduction would result in a clinically meaningful decrease of cardiovascular complications is still under investigation.

Aged↗
PubMed1996

[Secretion of endothelin-1 by cultured human normal adrenal cells].

Endothelin (ET) is a vasoactive peptide produced by some other types of cells in addition to endothelial cells. The authors investigated into the possibility of ET-1 secretion by cultured human normal adrenal cells. Human normal adrenal cells were prepared by 2% collagenase digestion for 1.5 hours and cultured in DMEM supplemented with 10% FCS. Angiotensin I (10(-9)-10(-7) mol/L) was added to the experimental groups on the 7-9th days of cultivation. Mediums were collected after 24 hours and the levels of aldosterone, cortisol and ET-1 in the mediums were measured by RIA. Other than aldosterone and cortisol, ET-1 was detected in the cultured mediums of human normal adrenal cells. And the secretion of ET-1 was stimulated by angiotesin I. Therefore, it is proposed that ET-1 may play a role by autocrine or paracrine in the human normal adrenal gland.

Adrenal Glands↗
PubMed1996

[Lipoprotein (a) and non-insulin dependent diabetes mellitus].

To study the relationship of the concentration of serum lipoprotein (a) [Lp(a)] with diabetic complications in non-insulin dependent diabetes mellitus (NIDDM), 100 non-diabetics with 150 patients with NIDDM were compared. There was no difference in Lp(a) concentration (P > 0.5) between the two groups. Lp(a) concentration was not significantly correlated with the levels of total cholesterol, low-density lipoprotein cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), HDL2-C, HDL3-C, apolipoprotein A-I, apolipoprotein B in both groups. In NIDDM group, patients with hypertension, macro- and microangiopathy had higher levels of Lp(a) than those without these complications (P < 0.001 and P = 0.002 respectively). Lp(a) level was positively related to presence of macroangiopathy (r = 0.185, P = 0.024) and proteinuria (r = 0.316, P < 0.001) in NIDDM.

Adult↗
PubMed1996

[RAAS changes due to dysfunction of pulmonary ventilation].

OBJECTIVE: RAAS was determined to investigate the relationship between their changes and the dysfunction of pulmonary ventilation for evaluating the pathogenesis of early pulmonary hypertension in chronic bronchitis with or without emphysema. METHODS: Angiotensin II (AT II), plasma renin activity (PRA) and aldosterone (Ald) were determined at 8:00 AM in sitting position for 30 minutes in 12 heathy nonsmokers, 50-60 years old, with normal functions of small airway, normal FEV1 and lung volumes, and in 23 patients with chronic bronchitis with or without emphysema. RESULTS: All patients with chronic bronchitis showed dysfunction of small airway with or without abnormalities of FEV1 and lung volumes. In healthy control group, the plasma PRA, AT II and Ald levels were 0.22 +/- 0.12 microgram.L-1.h-1 (x +/- sx), 52 +/- 7 ng/L and 315 +/- 26 pmol/L respectively comparing with those levels of 0.43 +/- 0.11 microgram.L-1.h-1, 197 +/- 32 ng/L and 388 +/- 59 pmol/L in aged patients with chronic bronchitis. It was found that dysfunction of small airway alone could cause remarkable elevation of PRA and AT II levels. In patients with mild pulmonary emphysema, the levels of PRA and AT II were significantly increased. The moderate pulmonary emphysema induced greatly increase of PRA, AT II and Ald levels. In patients with severe pulmonary emphysema, however, the plasma levels of PRA and AT II were significantly attenuated from the levels in moderate pulmonary emphysema while Ald level was still getting higher. There were no evidence to indicate the relationship between the changes of RAAS and hypoxemia. CONCLUSION: The elevation of AT II and PRA might partly be the pathogenesis of early pulmonary hypertension in COPD.

Aldosterone↗
PubMed1996

[Characterization of insecticidal crystal proteins of Bacillus thuringiensis subsp. chinensis CT-43].

Bacillus thuringiensis subsp. chinensis CT-43, no flagellum, produces various shaped parasporal crystals, which consist of 140000, 130000, and 65000 proteins. Based on two kinds of mutant, 140000 and 130000 crystal protein individually forms bipyramidal crystal and the 65000 protein forms cubidal crystal, and that the 140000 and 130000 protein is activated by trypsin into 55000 and 66000 proteins and 60000 protein, respectively. Bioassay were conducted to 3rd instar Plutella xylostella larvae with crystals, soluble crystal proteins, and activated crystal proteins, respectively, and it indicated that high toxic mutants can be obtained by curing low toxic crystal genes, and that the toxicity of crystals can be improved 16.3 to 58.4 times after solubilization.

Animals↗
PubMed1995

Site-directed mutagenesis of proteolytic antibody light chain.

Amino acid residues in a proteolytic antibody light chain selected by molecular modeling were substituted with Ala by site-directed mutagenesis. Hydrolysis of vasoactive intestinal polypeptide (VIP), the immunogen employed to elicit the antibody light chain, was reduced by > 95% by replacement of Ser27a or His93 by Ala residues. Similar reductions in the activity were observed using synthetic protease substrates containing Arg-methylcoumarinamide (MCA) and Lys-MCA bonds. Turnover of the Ser27a and His93 mutants was lower than that of wild-type protein by about two orders of magnitude. The activity of the wild-type protein was inhibited selectively by diisopropylfluorophosphate (DFP), a serine protease inhibitor, but the residual activity of the Ser26 mutant was refractory to DFP. The affinity of the wild-type light chain for the substrate ground state was nearly unaffected by mutations at Ser27a and His93. In contrast, a Ser26 single mutant and a His27d/Asp28 double mutant displayed increased Km (by about tenfold) and increased turnover (by about tenfold) using VIP as substrate. The kinetic constants for these mutants and the wild type protein were essentially identical with Boc-Glu-Ala-Arg as substrate. Thus, two types of residues participating in catalysis by the light chain have been identified. Ser27a and His93 are essential for catalysis but not for initial high affinity complexation and substrate. Ser26 and His27d or Asp28 participate in VIP binding and limit turnover indirectly.

Amino Acid Sequence↗
PubMed1995

Methodology for evaluating the incidence of second primary cancers with application to smoking-related cancers from the Surveillance, Epidemiology, and End Results (SEER) program.

The Surveillance, Epidemiology, and End Results (SEER) database is used to estimate the standardized incidence ratios (SIRs) of second primaries for all pairs of smoking-related cancers and to interpret the results in the context of our knowledge of the known effects of smoking on the incidence of each of the individual cancers. In evaluating the simultaneous incidence of two cancers, one must recognize the inherent duality of the two relevant SIRs linking the two cancers (e.g., A and B), namely, the SIRs of A following B and B following A. Under fairly general assumptions, the two SIRs are seen to be equal, and departures from equality suggest changes in risk status or the introduction of new risk factors after the incidence of the first primary. Based on these observations, a methodological strategy is developed. The data reveal several clear patterns. First, short-term incidence is uniformly much greater than long-term incidence. Second, the SIRs are consistently much higher for women than for men, for every pair of cancers studied. Third, the magnitudes of the SIRs are generally high and often substantially higher than would be expected on the basis of the known risks of smoking. Exceptionally high SIRs are observed between kidney and bladder cancer and between head and neck and esophageal cancer. Various influences may affect these high observed SIRs, including artifactual influences such as diagnostic, surveillance, and misclassification biases, and the effect of different exposure prevalences on subsequent SIRs, which may to some extent explain the strong sex differences. However, these artifacts do not appear to explain the magnitude of the observed SIRs, especially the very strong associations between kidney and bladder cancer and between head and neck and esophageal cancer. It seems likely that other factors play a role, including, possibly, host susceptibility factors or additional common risk factors other than smoking. Although multiple primary cancers are rare, they represent an especially fruitful population for detailed epidemiologic study.

Evaluation Studies as Topic↗