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Biomedical subjects

B Zhang

Publications and source records attributed to B Zhang.

At least 685 records · Page 38Linked to original sources
PubMedDate not supplied

Effects of high-dose troglitaz one on insulin sensitivity and beta-cell function in Watanabe heritable hyperlipidemic rabbits.

UNLABELLED: To clarify the dose-response effects of troglitazone on insulin sensitivity and beta-cell function, we examined the effects of high-dose troglitazone (100 mg/day per animal, administered as a food admixture) on glucose and insulin metabolism in hyperinsulinemic Watanabe heritable hyperlipidemic (WHHL) rabbits, and compared the results with our previous results with low-dose troglitazone (10 mg /day per animal). MATERIALS AND METHODS: Glucose and insulin metabolism were quantitatively characterized by a minimal model technique as reported previously. RESULTS: When troglitazone was administrated at a high dose for 6 months, it reduced hyperinsulinemia as reflected by a reduced basal (steady-state) insulin concentration lb and the insulin response to a glucose load, improved beta-cell function as reflected by decreased second-phase post-hepatic insulin delivery to glucose phi2, and reduced insulin resistance as reflected by increased insulin sensitivity to glucose disposal Si, without affecting glucose tolerance as reflected by an unchanged rate of glucose utilization Kg or insulin-independent glucose disposal Sg. The reductions in Ib and phi2 and the increases in Si in WHHL rabbits treated with a high dose of troglitazone were greater (p<0.05) than those observed in WHHL rabbits treated with a low dose of troglitazone, as assessed by a two-way repeated measures analysis of variance and the Wilcoxon-Mann-Whitney test. CONCLUSION: In WHHL rabbits, troglitazone dose-dependently reduced hyperinsulinemia, improved beta-cell function, and increased insulin sensitivity.

Animals↗
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Diurnal rhythms of blood pressure, heart rate, and locomotor activity in adult and old male Wistar rats.

The diurnal rhythms of systolic blood pressure (SBP), diastolic BP (DBP), heart rate (HR), and spontaneous locomotor activity (SLA) were determined in adult (6-month-old) and old (24-month-old) male Wistar rats by using radiotelemetry. The rhythm parameters (mesor, amplitude, acrophase, and percent rhythm) were analyzed by Fast-Fourier Transform and Cosinor methods. We found that the 12-h mean values of SBP, DBP, HR, and SLA were significantly (p<0.001) higher in the dark phase than in the light phase in both adult and old rats. The nocturnal 12-h mean value of HR was significantly (p<0.01) lower in old than in adult rats. In addition, the differences between diurnal and nocturnal 12-h mean values of SBP and HR were reduced in old rats. There was no significant difference in the 12-h mean values of SBP, DBP, and SLA between old and adult rats. Otherwise, the diurnal HR rhythm amplitude was significantly (p<0.01) reduced in old rats (32+/-2 vs. 46+/-2 bpm). A nearly 1-h delay in SBP and DBP acrophases (03h55 +/- 00h19 vs. 02h57 +/- 00h14 and 03h17 +/- 00h13 vs. 01h53 +/- 00h22, respectively) was found in old rats comparing to adult rats. No significant change in SLA diurnal rhythm was observed in old rats. In conclusion, these results show a decrease in the nocturnal 12-h mean value of HR and an alteration in cardiovascular diurnal rhythms by a 1-h delay of SBP and DBP acrophases and a reduction of HR rhythm amplitude in old Wistar rats.

Aging↗
PubMedDate not supplied

Mechanism of PCBs formation from the pyrolysis of chlorobenzenes.

Polychlorinated biphenyls (PCBs) were formed by pyrolysis of chlorobenzenes in a HCl atmosphere. Varieties of substituted chlorobenzenes were used as model compounds to optimize the condensation reaction. Lower chlorinated benzenes produce more PCBs than that of higher ones. Up to 0.7 microg PCBs/mg 1,2,3-trichlorobenzene was produced through the condensation reaction.

Chlorine Compounds↗
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5'-sulfhydryl-modified RNA: initiator synthesis, in vitro transcription, and enzymatic incorporation.

The detailed syntheses of the sulfhydryl-modified guanosine monophosphates 5'-deoxy-5'-thioguanosine-5'-monophosphorothioate (GSMP), O-[omega-sulfhydryl-tetra(ethylene glycol)]-O-(5'-guanosine) monophosphate (5'-HS-PEG4-GMP), and O-[omega-sulfhydryl-di(ethylene glycol)]-O-(5'-guanosine) monophosphate (5'-HS-PEG2-GMP) are reported. Transcription reactions employing GSMP, 5'-HS-PEG4-GMP, or 5'-HS-PEG2-GMP as the initiator nucleotide for T7 RNA polymerase introduce a thiol group at the 5'-end of RNA. The efficiency of thiol incorporation at the 5'-terminus of modified RNA compounds was assayed with three different thiol-reactive biotinylated reagents followed by streptavidin gel-shift methods. The transcription efficiency with various ratios of GTP to 5'-HS-PEG2-GMP was explored by reaction with a sulfhydryl-reactive maleimide-conjugated protein. This is an efficient method to incorporate enzymatically a thiol group into the 5'-end of RNA.

Biotinylation↗
PubMedDate not supplied

Near-field mapping of the emission distribution in semiconductor microdiscs.

We have used a scanning near-field optical microscope to study the fluorescent light distribution in the near- and far-fields with two types of microdiscs, InGaP and GaN, fabricated in our laboratory. The InGaP microdisc has a radius of 2.5-5.0 microm, a thickness of 0.15-0.2 microm and a circular shape and the GaN disc has a radius of 5-8 microm with a thickness of 0.5-2 microm. Spontaneous emission enhancement in these microdiscs has been observed with emitting wavelengths of 650 and 550 nm respectively In both types of microdisc, the whispering-gallery mode (WCM) has been observed on the top surface using near-field optical and far-field microscopic methods. However, due to the different disc structures and optical confinements, the light distributions of the type types of disc are quite different. In the case of the InGaP disc, WGM is the dominant mode with a mixture of other modes. Interference-like ring intensities have been observed both inside the disc surface and outside, with a period ratio of 1:2. In addition, the propagating waves emitted from the side of the disc have been collected for the first time by using near-field optical microscopy. A theoretical calculation based on the theory of optical modes in microdisc lasers confirmed this observation. It also predicted the behaviour of the electric field distribution (transverse electric) inside and outside the disc, as well as the period of the wave propagation. In contrast, the near-field mapping of the GaN fluorescence showed not only a ring-like emission intensity along the circumference of the disc, an indication of WGM, but also an even intensity distribution inside the disc. This can be explained as the combination of the WGM with the Fabry-Perot mode of multi-reflection between the GaN layer and the substrate. The results also demonstrate the potential application of near-field optics to explore the light emission mode of a microdisc on a nanometre scale.

Journal Article↗
PubMedDate not supplied

Control of a total artificial heart using mixed venous oxygen saturation.

We developed a control of the total artificial heart (TAH) using mixed venous oxygen saturation (SvO2). With this method, the TAH output was controlled by automatically adjusting drive parameters in response to changes in measured SvO2. The feasibility and validity of this method were evaluated in a series of treadmill exercise tests using a calf implanted with a pneumatic TAH. The cardiac output (CO) and SvO2 were measured with an ultrasonic flowmeter and an oximetric catheter, respectively. The calf performed graded exercise under a fixed drive control mode (fixed mode), in which the drive parameters were unchanged throughout the treadmill test, and under the SvO2 based control mode (SvO2 mode). The calf could go to Stage 6 in both modes, but the maximal oxygen consumption in the SvO2 mode was 1.5 times as large as that of the fixed mode. Compared with the fixed mode, CO was increased effectively in the SvO2 mode, and the capacity for exercise was augmented. When considering the relationship between oxygen consumption and oxygen delivery, it was revealed that the CO in the SvO2 mode responded more adequately to the recipient's oxygen demand than that in the fixed mode. We conclude that this SvO2 based control method is feasible and physiologically effective.

Animals↗
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Noninvasive assessment method to determine the anatomic compatibility of an implantable artificial heart system.

To assess the anatomic compatibility of an artificial heart (AH), we attempted to develop a computer environment that would facilitate a reliable simulation of an AH implanted in the human thorax. A three-dimensional thoracic computer model with a ventricle-resected heart was constructed, by using manually extracted contour points of the aorta, pulmonary artery, atria, atrioventricular valves, diaphragm, and thoracic wall from a set of consecutive CT images. Such a model enabled simulation of an AH implantation by orienting the AH model in it. Error evaluation on CT imaging and contour extraction with a Plexiglas cylindrical phantom showed that the diameter of the extracted phantom contour was approximately 2 mm smaller than its original with a standard deviation of <0.5 mm. Errors in contour and surface reconstruction could be reduced to far less than 1 mm under constrained conditions. A study on the influence of breathing revealed that variations in some thoracic dimensions between inspiration and expiration could reach 10 mm. In summary, computer simulation of AH implantation is a worthwhile approach with acceptable accuracy, although further considerations of extreme thoracic situations will be required.

Computer Simulation↗
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Mixed venous oxygen saturation as a promising parameter for physiologic control of total artificial heart.

Mixed venous oxygen saturation (SvO2) has been proposed as one of the suitable parameters for physiologic control of a total artificial heart (TAH). To establish the practical application of SvO2, we investigated the response of cardiac output (CO) and SvO2 to step-loaded exercise. A normal calf was surgically equipped with an ultrasonic flowmeter probe and an oximetry catheter in the pulmonary artery to measure CO and SvO2, respectively. Three stage step treadmill exercise tests (1, 2, and 4 km/h) were performed three times. While CO increased from 8.9 L/min at preexercise level to 9.7, 10.2 and 11.4 L/min at 1, 2, and 4 km/h, respectively, SvO2 decreased from 59.6% to 56.8, 55.3, and 52.2%, respectively. There existed a linear correlation between the magnitude of changes in CO and SvO2. CO and SvO2 exhibited a similar course of change, expressing an inverted exponential curve. The time constant of SvO2 was from 19 to 35 seconds, whereas that of CO was from 21 to 39 seconds. We conclude that SvO2 changes in close association with CO during exercise and has good potential to be a parameter for physiologic control of a TAH, by reflecting the recipient's CO demand without conspicuous time delay.

Animals↗
PubMedDate not supplied

Colonoscopic evaluation of immunochemical fecal occult blood test for detection of colorectal neoplasia.

BACKGROUND/AIMS: This study was carried out to assess the validity of three testing methods of immunochemical occult blood according to the number of collection times as a means for colorectal cancer screening. METHODOLOGY: Four thousand six hundred and eleven asymptomatic individuals, who received both an immunochemical occult blood test with a three-day method and colonoscopy during a medical checkup, served as subjects for this study. For evaluation of the desirable number of sampling times, we used the results of the first day for the 1-day method, the results of the first and second days for the 2-day method, and the results of three-consecutive days for the 3-day method. Sensitivities and specificities of these three testing methods were evaluated. RESULTS: Sensitivities and specificities for colorectal cancer were calculated to be 56% and 97% for the 1-day method, 83% and 96% for the 2-day method, and 89% and 94% for the 3-day method, respectively, showing a significant difference in sensitivity between the 1-day and the 2-day methods, as well as the 3-day method (p < 0.01), and in specificity between the 1-day as well as the 2-day and 3-day methods (p < 0.05). CONCLUSIONS: These findings indicate that the immunochemical fecal occult blood test is useful for the diagnosis of colorectal cancer, and that 2-day testing is recommended as a means of screening for colorectal cancer.

Adenoma↗
PubMedDate not supplied

A comparative study of immunochemical fecal tests for detection of colorectal adenomatous polyps.

BACKGROUND/AIMS: This study was conducted to assess the diagnostic validity of new different immunochemical fecal occult blood tests for colorectal adenomatous polyps, including reversed passive hemagglutination test (Immudia-HemSp), combination monoclonal antibody guaiac test (Monohaem), latex agglutination inhibition test (Iatro Hemcheck), and latex agglutination tests (LA Hemochaser, OC-Hemodia). METHODOLOGY: Two hundred and fifty patients with colorectal adenomatous polyps 1.0 cm or larger in diameter and the same number of healthy controls served as subjects for the study. Each subject received a set of 5 immunochemical tests within 3 consecutive days, and sensitivities and specificities of these tests were evaluated. RESULTS: Mean sensitivity and specificity in a set of 5 immunochemical tests were 47.6% and 95.8%, respectively. Sensitivities and specificities of 5 different immunochemical tests were calculated as 47.6% and 96.8% for Immudia-Hem Sp, 46.8% and 95.2% for Monohem, 46.4% and 95.2% for Iatro Hemchek, 48.0% and 96.4% for LA Hemochaser, and 49.2% and 95.6% for OC-Hemodia, respectively, showing no significant difference in sensitivity and specificity among the 5 tests. CONCLUSIONS: These findings suggest that there is no difference in the degree of accuracy for colorectal adenomatous polyps among several types of immunochemical fecal occult blood test.

Adenomatous Polyposis Coli↗
PubMedDate not supplied

Characteristics and survival rate of elderly patients with colorectal cancer detected by immunochemical occult blood screening.

BACKGROUND/AIMS: A comparative study was carried out to clarify the clinicopathological features and survival rate of elderly patients with colorectal cancer diagnosed by immunochemical fecal occult blood screening. METHODOLOGY: The study subjects included 208 patients with colorectal cancer, who were divided into 2 groups based on their ages: 52 patients aged 75 years and over (older group) and 156 patients aged 50-74 years (younger group). The 2 groups were compared in terms of their individual factors, including site, size, Dukes' classification, histo-pathological type of their cancer lesions and 5-year survival rate. RESULTS: There was a significant difference in prevalence of tumor sites between the older and younger groups (P < 0.05). Particularly, the frequency of right colon cancers was higher in the older group (34.6%) than in the younger group (20.5%), but there were no differences found in any other factors such as size, Dukes' classification, and histopathological type. Survival rate was almost the same between the 2 groups. CONCLUSIONS: These results suggest that elderly patients are susceptible to right colon cancer but there is no difference in the clinicopathological characteristics and 5-year survival rate between older and younger patients with colorectal cancer detected by immunochemical fecal occult blood test. The older as well as younger people should be encouraged to attend the screening program for colorectal cancer by immunochemical fecal occult blood test.

Adenocarcinoma↗
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Association of diverticulosis coli and vascular ectasias and the results of fecal occult blood test.

BACKGROUND/AIMS: This study was conducted to clarify the diagnostic value of an immunochemical fecal occult blood test for diverticulosis coli and vascular ectasias of the colon, and to assess the association of these diseases to the results of fecal occult blood test. METHODOLOGY: An immunochemical fecal occult blood test over 2 consecutive days was carried out on 72 patients with diverticulosis coli, on 36 patients with vascular ectasias of the colon, on 36 patients with colon cancer, and on 144 healthy subjects. RESULTS: The test was positive in 13.8% patients with diverticulosis coli, in 11.1% patients with vascular ectasias, in 83.3% patients with colon cancer, and in 6.2% healthy subjects, respectively, showing a significant difference in the detection rate between colonic diverticulosis and colon cancer, between vascular ectasias and colon cancer (P < 0.001). However, there was no significant difference in the detection rate between diverticulosis coli and healthy subjects, and between vascular ectasias and healthy subjects. In addition, there was no significant association between the degrees of diverticulosis coli and vascular ectasias to the results of immunochemical fecal occult blood test. CONCLUSIONS: These findings indicate that the immunochemical fecal occult blood is unsuitable for the diagnosis of the patients with colonic diverticulosis and patients with vascular ectasias, and these disorders have little influence on the results of fecal occult blood test.

Colon↗
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Streptococcal preparation OK-432 enhances the antitumor activity of CPT-11 by increasing Th1-cytokine production in mice.

BACKGROUND: The streptococcal preparation OK-432 is an immunomodulator widely used for cancer therapy in Japan. The purpose of this study was to evaluate the efficacy of the combined treatment of OK-432 and CPT-11. MATERIALS AND METHODS: In C57BL/6 mice inoculated with B16 melanoma, the antitumor mechanism of this combined therapy was investigated through an analysis of cytokine production by the splenocytes. RESULTS: SN-38, the active metabolite of CPT-11, exerted dose-dependent inhibition of interferon (IFN)-gamma production induced by OK-432 in mouse splenocytes. In contrast, the optimum concentration of SN-38 increased interleukin (IL)-6 and IL-12 production by OK-432-activated splenocytes. In tumor-bearing mice, CPT-11 inhibited tumor growth and OK-432 had an additive antitumor effect with CPT-11. Investigation of cytokine production showed that CPT-11 treatment principally inhibited IL-12 and IFN-gamma production, which was improved by the combined administration with OK-432. CONCLUSION: These results indicate that CPT-11 inhibits type-1 T helper (Th1) cells despite its potential to stimulate macrophages and that OK-432 enhances the antitumor activity of CPT-11 by increasing Th1-cytokine production.

Animals↗
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Effects of manidipine and delapril on serum lipids, lipoproteins, and apolipoproteins in patients with mild to moderate essential hypertension: a randomized trial with one-year follow-up.

Forty-five patients with mild to moderate essential hypertension were randomly assigned to receive 10 to 40 mg of manidipine HCl or 15 to 60 mg of delapril daily for 12 months. In the manidipine-treated group were 13 women and 5 men (mean age, 48.2 years) and in the delapril-treated group 11 women and 11 men (mean age, 53.7 years). Blood samples were taken at baseline and after 6 and 12 months of treatment and again at 2 months after treatment discontinuation. Significant reductions in blood pressure were observed in both treatment groups. The reduction in diastolic blood pressure was significantly greater in the manidipine-treated patients than in the delapril-treated patients; no significant between-groups differences in systolic blood pressure were noted. Heart rate increased significantly in the manidipine group. No changes in serum levels of total cholesterol, triglycerides, and high-density and low-density lipoprotein cholesterol were noted during or after treatment. In the manidipine group, a small but significant decrease in apolipoprotein (apo) A-I and an increase in lipoprotein(a) were found at 6 months and a significant increase in apo A-II and apo E at 12 months; in the delapril group a significant decrease in apo A-I was found at 6 months. The results indicate that both manidipine and delapril are lipid-neutral antihypertensive drugs, since neither drug greatly affected serum lipid metabolism.

Adult↗
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Colorectal adenomatous polyps detected by immunochemical occult blood screening.

BACKGROUND/AIMS: This study aimed to evaluate the validity of immuno-chemical occult blood screening for colorectal adenomas and to clarify the characteristics of this disease which are detected. METHODOLOGY: We studied 140 colorectal adenomas and 140 healthy controls in a hospital based case control study, in which three-day testing was conducted to assess the accuracy of the immuno-chemical occult blood screening test (total 280 patients). A further 80 colorectal adenomas 1 cm or larger, which were detected by a screening program, were compared with matched cases detected by the outpatient clinics (total 160 patients). A comparison of characteristics including tumor location, shape and histology was made between the two groups. RESULTS: Sensitivity and specificity were calculated to be 46% (61% for tumors larger than 1 cm, 30% for those less than 1 cm), and 96% respectively, showing a significant difference in sensitivity between large and small adenomas (p < 0.01). The proportion of rectal adenomas was significantly higher in the outpatient clinics (41%) than in the screening program (21%) (p < 0.05), whereas no differences were noted in the other measures. CONCLUSIONS: These results suggest that immuno-chemical occult blood is inadequate as a screening test for detecting small adenomas, as t can not differentiate between the detection of rectal adenomas from large adenomatous polyps.

Adult↗
PubMedDate not supplied

Immunologic detection of fecal occult blood from upper digestive tract diseases.

BACKGROUND/AIMS: This study was conducted to evaluate the accuracy of the immunochemical occult blood test for upper digestive tract diseases. METHODOLOGY: The test was performed on 226 subjects, including 124 upper digestive tract diseases (12 ulcerative esophagitis cases, 10 esophageal cancer cases, 33 gastric ulcer cases, 33 gastric cancer cases, and 36 duodenal ulcer cases), 34 colorectal cancer cases, and 68 healthy subjects, after which, the accuracy of this test was evaluated. RESULTS: The test was positive 23 in upper digestive tract diseases (2 in ulcerative esophagitis, 2 in esophageal cancer, 5 in gastric ulcer, 8 in gastric cancer, 6 in duodenal ulcer), 31 in colorectal cancer, and 3 in healthy subjects, respectively. Thus, the sensitivity was 19% for upper digestive tract diseases (16.7% for ulcerative esophagitis, 20% for esophageal cancer, 15% for gastric ulcer, 24% for gastric cancer, 20% for duodenal ulcer) and 91% for colorectal cancer, and the specificity was 96%. Significant difference was noted in the sensitivity between upper digestive tract diseases and colorectal cancers (p0.001), whereas there was no difference among 5 upper digestive tract diseases. CONCLUSIONS: These results indicate that the immunochemical occult blood is inadequate as means for detection of upper digestive tract diseases, and that an examination of upper digestive tract is unnecessary in cases where the immunochemical occult blood test is positive, but there is no evidence of diseases in colon and rectum.

Esophageal Diseases↗