Search PubMed⌕ Search

Biomedical subjects

M Zhu

Publications and source records attributed to M Zhu.

At least 217 records · Page 12Linked to original sources
PubMed1997

Impaired beta-cell function and deposition of fat droplets in the pancreas as a consequence of hypertriglyceridemia in OLETF rat, a model of spontaneous NIDDM.

Hypertriglyceridemia is known to be a feature of obesity-related NIDDM, but the patho-etiological significance of this association is obscure. The effects of triglycerides (TGs) on beta-cell function and morphological changes in pancreas were examined using in vivo and in vitro approaches in male OLETF rats at ages 6, 12, and 30 weeks, with their diabetes-resistant counterpart, LETO rats, as normal controls. The results showed that, in the fasting state, plasma TGs in OLETF rats were increased 2.5-fold at age 6 weeks, 3.3-fold at age 12 weeks, and 6.2-fold at age 30 weeks, compared with age-matched LETO rats. The TG content in islets from 12-week-old OLETF rats was significantly increased when compared with those from their age-matched counterparts, but this was not the case with the 6-week-old OLETF rats. Therefore, the islets from 6-week-old rats were cultured with either free fatty acids (FFAs; 1.0 mmol/l sodium oleate) or TG (5.0 mmol/l Intralipide) for 72 h. Several abnormalities in OLETF rats were evident, in contrast to the results from control LETO rats: 1) glucose-induced insulin secretion was more inhibited by either FFAs or TGs in the presence of 27.7 mmol/l glucose, a result associated, at least in part, with reduced glucokinase activity in the islets; 2) a marked elevation in TG content was found in the islets; and 3) the deposition of fat droplets in the enlarged islets, even in the beta-cells, was found by Oil Red O-insulin double staining at age 30 weeks. In conclusion, hypertriglyceridemia resulted in significant TG stores in the islets, which subsequently inhibited glucose-induced insulin secretion, at least in part, via reduced glucokinase activity in the islets. Fat droplets in islets, therefore, may play an important role in hastening the development of NIDDM in this rat model.

Animals↗
PubMed1997

D-glucose stimulates mesangial cell GLUT1 expression and basal and IGF-I-sensitive glucose uptake in rat mesangial cells: implications for diabetic nephropathy.

The complications of diabetes arise in part from abnormally high cellular glucose uptake and metabolism. To determine whether altered glucose transporter expression may be involved in the pathogenesis of diabetic nephropathy, we investigated the effects of elevated extracellular glucose concentrations on facilitative glucose transporter (GLUT) expression in rat mesangial cells. GLUT1 was the only transporter isoform detected. Cells exposed to 20 mmol/l glucose medium for 3 days demonstrated increases in GLUT1 mRNA (134%, P < 0.002), GLUT1 protein (68%, P < 0.02), and V(max) (50%, P < 0.05) for uptake of the glucose analog [3H]2-deoxyglucose (3H2-DOG), when compared to cells chronically adapted to physiologic glucose concentrations (8 mmol/l). The increase in GLUT1 protein was sustained at 3 months, the latest time point tested (77% above control, P < 0.01). In contrast, hypertonic mannitol had no effect on GLUT1 protein levels. Insulin-like growth factor I (IGF-I; 30 ng/ml) increased the uptake of 3H2-DOG by 28% in 8 mmol/l glucose-treated cells (P < 0.05) and by 75% in cells switched to 20 mmol/l glucose for 3 days (P < 0.005). These increases in 3H2-DOG uptake occurred despite a lack of effect of IGF-I on GLUT1 protein levels (P > 0.5 vs. control). Therefore, hyperglycemia and IGF-I treatment both lead to increases in mesangial cell glucose uptake, and hyperglycemia induces increased GLUT1 expression, which can directly lead to the pathological changes of diabetic nephropathy. The effects of high glucose and of IGF-I to stimulate 3H2-DOG uptake also appear to be additive.

Animals↗
PubMed1997

[The establishment and evaluation of abdominal aorta thrombosis model in rat].

An animal model of abdominal aorta thrombosis based on Virchow's thrombosis principle was induced by endothelium denudation with a polyethylene catheter combining severe stenosis with an aortic constriction in rats. A total of 37 rats were involved in thrombosis induction. Among them thrombus developed in 27 rats. Mean length of thrombus was 8.53 +/- 1.42 mm. The contractibility of vascular wall in the thrombotic group significantly reduced.

Animals↗
PubMed1997

[Study on dietary pattern and nutrients intakes of residents in areas of high and low incidence of esophageal cancer].

The dietary pattern and nutrients intakes of residents in areas with high and low prevalence of esophageal cancer were studied by 3 days' dietary survey. The results showed that the dietary pattern and nutrients intakes of residents in areas with low prevalence (ALP) of esophageal cancer was superior to that in area with high prevalence (AHP). The amount of soybean, meat and vegetable consumed by residents in the ALP was more than that in the AHP. Deep color vegetable and gaelic vegetable were dominant in ALP, but so were light color vegetables in AHP. The protein quality and quantity as well as the amount of Zn, Ca, RE and riboflavin consumed in the AHP were lower than that in the ALP. The energy from carbohydrate accounts for 78.14% of the total in the AHP. It is suggested that poor dietary pattern and the quality and amount of nutrients intake may be related to the development of esophageal cancer, and nutrition intervention in area of high prevalence seems rational.

Adolescent↗
PubMed1997

[Light microscopic observation of bone interface of titanium-coated 317L plate screw].

The observational results of bone interface of titanium-coated 317L plate screw and 317L plate screw under light microscope are reported in the present paper. Osseointegration was formed in both kinds of screws after implanting. In the titanium-coated 317L plate screw group, the inflammatory reaction was slighter, the new bone formed earlier in the interface and the bone was combined with the metal tightly, whereas in the uncoated 317L plate screw group, the relationship between the bone and metal was only a state of contact. These indicate that the bone interface and tissue compatibility of titanium-coated 317L plate screw may be better than that of the 317L plate screw.

Animals↗
PubMed1997

[An investigation on the epidemiology of injuries in middle school students].

In November 1996, we made an investigation among 1194 students from 25 of grade 2 classes at 4 middle schools in our city. The result shows that a total of 13 different kinds of injuries happened to the students, with a rate of 81.66%. Among which, 7 kinds of injuries took the first 7 places: injuries from falls (39.78%), knife-cutting (37.68%), throat injuries by sharp bone blocks (36.09%), traffic accidents (18.17%), bumping to sharp materials (17.08%), burns (17.08%) and by sharp-weapon hurt (16.83%). We also made an investigation on the causes and characteristics and related factors of injuries. Thus some preventive measures were preliminarily put out.

Accidental Falls↗
PubMed1997

Phenotypic stability of a cytotoxic T-cell line directed against an immunodominant epitope of human carcinoembryonic antigen.

CTL lines have now been generated against defined peptides of a range of human tumor-associated antigens (TAAs). One of the potential uses of these epitope-specific CTLs is in adoptive transfer immunotherapy. This is a modality, however, that will require long-term in vitro culture of CTLs. To date, little has been reported concerning the phenotypic stability of human epitope-specific CTLs as a consequence of long-term in vitro propagation via peptide stimulation. We report here the serial phenotypic characterization of a CTL line directed against an immunodominant epitope (YLSGANLNL, designated CAP-1) of human carcinoembryonic antigen (CEA). This CTL line was derived from peripheral blood mononuclear cells of a patient with metastatic carcinoma who had been treated with a recombinant CEA-vaccinia vaccine in a Phase I trial; the CTLs were analyzed through 20 in vitro cycle passages of stimulation with CAP-1 peptide and interleukin 2 in the presence of autologous antigen-presenting cells. The CTL line was shown to be phenotypically stable in terms of high levels of cytokine (IFN-gamma, tumor necrosis factor, and granulocyte-macrophage colony-stimulating factor) production, expression of homing-adhesion molecules, ability to lyse peptide-pulsed targets, and ability to lyse human carcinoma cells endogenously expressing CEA in a MHC-restricted manner. Vbeta T-cell receptor gene usage was also analyzed. These studies thus present a rationale for the use of long-term cultured epitope-specific human CTLs, directed against a human TAA for potential adoptive transfer immunotherapy protocols.

Antigens, CD↗
PubMed1997

[Effects of green tea on growth inhibition and immune regulation of Lewis lung cancer in mice].

C57/BL6J mice were inoculated with Lewis lung cancer cells as an experimental model to study the effects of green tea on cancer prevention, inhibition of tumor growth and immune regulation in mice with tumor. Results showed that weight of thymus in C57/BL6J mice and its index declined, proportion of positive CD4 subgroup of T lymphocyte and ratio of CD4+, to CD8+ reduced, baseline chemilumi-nescence decreased in peripheral white blood cells, yeast zymosan stimulated chemiluminescence increased, and number of immunoglobulin M formation cells decreased. It indicated that green tea had obvious inhibition in Lewis lung cancer and protective effects, to various extent, on adverse changes of above indices.

Adjuvants, Immunologic↗
PubMed1997

[Clinical and experimental study on improving cellular immunological function of uterine myoma patients by xiaoliu tablet].

OBJECTIVE: To explore the effect of Xiaoliu Tablet (XLT) in treating uterine myoma (UM) and the relationship between effect and the cellular immunological function of the UM patients. METHODS: Seventy-one UM patients by treatment with XLT was observed. The activities of natural killer (NK) cells of 50 patients and 30 normal women were determined. RESULTS: There were good effect in reducing the volume of myoma and improving the menses by XLT, especially in patients whose myoma were singly and small. The activity of NK cells of these patients (24.61 +/- 6.04%, n = 50) was significantly different from that of normal women (45.42 +/- 9.05%, n = 30), P < 0.01. There was a notable rise of NK cells of the patients (37.54 +/- 5.01%, n = 39), after the treatment of six months by XLT (P < 0.01). CONCLUSION: Improving the immunological function might be one of the mechanisms of the effect of XLT.

Adjuvants, Immunologic↗
PubMed1996

Solid-state 13C-NMR spectroscopy of adduction products of 2,5-hexanedione with ribonuclease, albumin, and rat neurofilament protein.

The Paal-Knorr condensation reaction between the gamma-diketone 2,5-hexanedione (2,5-HD) and epsilon-amine moieties of proteins of various molecular weight, including ribonuclease (RNase), bovine serum albumin (BSA) and rat neurofilament (NF), has been investigated by solid-state 13C-NMR spectroscopy. These proteins all reacted with 2,5-HD with the formation of 2,5-dimethylpyrrole (2,5-DMP) derivatives. The size and complexity of the protein affected the rate of formation of 2,5-DMP derivatives. Using the selective reducing reagent NaCNBH3, the Paal-Knorr reaction intermediates were trapped by conversion into amines, which were identified by solid-state NMR spectroscopy. The secondary autoxidation reaction following the formation of 2,5-DMP derivatives was also studied by solid-state NMR spectroscopy.

Animals↗
PubMed1996

Oligonucleotide analysis by capillary polymer sieving electrophoresis using acryloylaminoethoxyethanol-coated capillaries.

Capillary polymer sieving electrophoresis using dynamic sieving polymer solutions provides size-based separations of oligonucleotides. The polymer sieving system described here resolves single-stranded oligonucleotides with single-base resolution up to lengths of 30 bases within 10 min. The effect of temperature on the separation of synthetic oligonucleotide standards was examined between 20 degrees C and 40 degrees C, with optimal performance at 35-40 degrees C. By adding urea to the sieving buffer single-base resolution could be extended to 60 bases in about 40 min. Best performance was achieved with capillaries coated with a new monomer, acryloylaminoethoxyethanol. This coating provides the necessary stability to ensure long lifetimes.

Acrylic Resins↗
PubMed1996

Tetrahydrobiopterin biosynthesis in C6 glioma cells: induction of GTP cyclohydrolase I gene expression by lipopolysaccharide and cytokine treatment.

The possibility that 5,6,7,8-tetrahydrobiopterin (BH4) biosynthesis is stimulated in glial cells by treatment with lipopolysaccharide (LPS) and tumor necrosis factor (TNF-alpha) was examined in the astrocyte-derived C6 glioma cell line. Under basal culture conditions BH4 levels were found to be at the limit of detection. Concurrent treatment with 10 micrograms/ml LPS and 50 ng/ml TNF-alpha caused a time-dependent 13-fold increase in the levels of BH4. This treatment paradigm also induced nitric oxide synthase activity, as evidenced by increased levels of nitrite, an oxidized metabolite of NO, in the culture medium. LPS and TNF-alpha treatment led to a 25-fold increase in GTPCH enzyme activity, the first and rate-limiting enzyme in BH4 synthesis, and a corresponding 23-fold increase in GTPCH protein levels. Northern blot analysis showed that increased levels of GTPCH mRNA preceded changes in GTPCH protein, GTPCH enzyme activity and BH4 levels and reached a maximal of 44-fold that was sustained for at least 48 h. These results demonstrate that LPS and TNF-alpha stimulate de-novo BH4 biosynthesis and suggest that C6 cells offer a model system for studying the molecular events that control the induction of GTPCH gene expression and BH4 synthesis in glial cells.

Animals↗
PubMed1996

TAR- and Tat-independent replication of human immunodeficiency virus type 1 in human hepatoma cells.

The molecular mechanisms involved in the regulation of human immunodeficiency virus type 1 (HIV-1) replication may differ in various cell types and with various exogenous stimuli. TAR/Tat interactions play important roles in HIV-1-long terminal repeat (LTR)-directed transcription, and have become specific targets in molecular therapies for blocking HIV-1 replication. As we previously reported, astrocytic glial cells, which can support HIV-1 replication in cell culture and may be infected in vivo, provide an intracellular milieu in which TAR mutant HIV-1 viruses may replicate. In further studies of this molecular model, several divergent human cell types were analyzed for both TAR- and Tat-independent HIV-1 replication. Human hepatoma cell lines, which can be productively infected by HIV-1 after the hepatoma cells are transduced with the human CD4 receptor gene, were found to support high levels of HIV-1 replication. In these studies, utilizing a transient transfection system with wild-type and various TAR, Tat, or combined TAR/Tat mutant HIV-1 proviral constructs, we demonstrate TAR-independent replication in unstimulated human hepatoma cells. Remarkably, in human hepatoma cells, HIV-1 replication is not only independent of TAR but also can be independent of Tat expression. It is further demonstrated, using electrophoretic mobility shift assays (EMSAs) and an in situ UV cross-linking system, that human hepatoma cells contain novel endogenous cellular proteins that bind to the proviral HIV-1 5' LTR in the downstream region, between nucleotides +38 to +125 on proviral DNA. This alternative regulatory pathway of TAR- and Tat-independent viral production may provide a new system to dissect further the interactions of Tat/TAR and determine the role of the TAR element, in its DNA form, in HIV-1 replication.

Base Sequence↗
PubMed1996

Differential V region mutation of two transfected Ig genes and their interaction in cultured B cell lines.

We have established B cell culture systems in which transfected and stably integrated Ig constructs spontaneously undergo high rates of variable (V) region mutation. Mutation rates were determined using reversion analysis of an Ig V region nonsense codon (Vn). A construct (Vn/gamma2a) in which a Vn was associated with the gamma2a constant region and its intervening and immediate flanking sequences mutated at a high rate of 2.2 x 10(-4)/bp/generation in the NSO myeloma cell line. This same Vn, when associated with the mu constant region (Vn/mu), mutated at a 1000-fold lower rate in NSO. The Vn/gamma2a construct also mutated at high rates in the 18.81 pre-B and the S107 myeloma cell lines and at a low rate in the J558 myeloma cell line. In NSO, the presence of the gamma2a construct raised the mutation rate of the mu construct and the mu decreased the mutation rate of gamma2a. These results suggest that there is both positive and negative regulation of V region mutation and that different cell lines express different combinations and/or amounts of trans-acting factors that are involved in the mutational process.

Animals↗
PubMed1996

Evaluation of feline leukemia virus control measures.

A susceptible-infected-recovered-susceptible (SIRS) model of the epidemiology of feline leukemia virus is formulated and analysed. The dynamics of the disease are dramatically different in no-risk, low-risk and high-risk subpopulations of asocial, free roaming, and multiple cat household cats. Among low risk (<1% prevalence) free roaming cats, the model predicts that an effective immunization rate of 4% year-1, or an effective removal rate of 8% year-1 are adequate to control the disease completely. Under higher risk (10% prevalence) conditions, an effective immunization rate of 23-72% year-1 or a removal rate of 69-145% year-1 are required for control. At very high (30%) prevalence rates, even heroic measures may not suffice to substantially reduce disease prevalence: a vaccination rate of 100% year-1 even if attainable, would only slightly reduce disease prevalence from 30% to 29%. We conclude that the current estimated effective feline leukemia virus immunization rate of 11-19% of the general population is inadequate to provide herd immunity in the subpopulation of cats which are genuinely at risk of infection. A substantial increase in the vaccination rate and/or intensification of test and removal efforts in the at risk population would be required to attain an effective level of protection.

Animals↗
PubMed1996

Pancreatic A-cell function in the partially pancreatectomized Otsuka Long-Evans Tokushima Fatty rat, a model of spontaneous non-insulin-dependent diabetes mellitus.

We examined whether a 70% pancreatectomy changes the morphofunctionality of pancreatic A cells in a model rat (Otsuka Long-Evans Tokushima Fatty [OLETF]) with non-insulin-dependent diabetes mellitus. Male OLETF rats aged 6 weeks were assigned to two groups: partial pancreatectomy (Px) and sham pancreatectomy (sham). The Px group was divided into three subgroups based on treatment received after surgery, which included treatment with nicotinamide, phlorhizin, or saline. As a control, their diabetes-resistant counterparts, Long-Evans Tokushima Otsuka (LETO) rats, were similarly treated and grouped. Six weeks after surgery, plasma glucagon responses to arginine- and insulin-induced hypoglycemia were examined. In addition, the glucagon content and morphological features of pancreatic A cells in Px-remnant and remnant-equivalent pancreata were investigated 7 weeks after surgery. A sustained nonfasting hyperglycemia was evident in Px OLETF rats, which was ameliorated by administration of nicotinamide. The glucagon content and A-cell mass were not decreased significantly in the remnant pancreas of saline- and phlorhizin-treated Px animals of either strain but increased in nicotinamide-treated animals compared with those in the remnant equivalent of the respective sham rats. The areas under the response curves of plasma glucagon (zigma IRG) during an arginine infusion test and 90 minutes of insulin-induced hypoglycemia were 1,010.7 +/- 72.9, 1,083.1 +/- 95.3, 1,029.6 +/- 65.0, and 1,779.8 +/- 226.9 pmol.L-1.min-1 versus 1,997.0 +/- 283.1,2,217.0 +/- 395.0, 1,479.6 +/- 78.0, and 3,466.4 +/- 174.0 pmol.L-1.min-1 in phlorhizin-, nicotinamide-, and saline-treated Px OLETF and sham OLETF rats, respectively. A similar trend was observed for differences in the response of pancreatic A cells to both stimuli among various groups of LETO rats. There was no significant difference in sigma IRGs during both tests between OLETF and LETO rats with similar treatments, except during an insulin tolerance test (ITT) in saline-treated Px rats. The magnitude of the plasma glucagon response to both stimuli in the test animals was roughly parallel to the glucagon content in the pancreas. These findings suggest that differences in the proliferation and responsiveness of pancreatic A cells between OLETF and LETO rats after a 70% pancreatectomy are not nearly as significant as compared with B cells.

Animals↗
PubMed1996

Capillary isoelectric focusing.

Capillary isoelectric focusing is a useful analytical technique for characterization of protein mixtures and determination of protein isoelectric points. It is particularly useful in separation of protein glycoforms (Fig. 5), characterizing protein microheterogeneity (Fig. 6), and resolution of charge variants (Fig. 7). The capillary focusing process is analogous to conventional isoelectric focusing in gels, while the requirement for zone mobilization is unique to the capillary format with on-tube detection. A variety of mobilization methods have been described, and the selection of the mobilization method for a particular application depends on the capillary type, the instrument configuration, and the type of proteins to be analyzed. Capillary IEF is generally successful for proteins with a molecular weight up to about 150,000 that exhibit good solubility in aqueous buffers, but may be unsatisfactory for large or hydrophobic proteins. Because of precipitation and variation in mobilization efficiencies, use of internal standards is recommended in most applications. Capillary IEF can be compared to conventional gel IEF in terms of sample throughput and sensitivity. Conventional gels require approximately 4-6 hr to cast, run, and stain the gel, depending on whether silver or Coomassie staining is used. A typical gel contains 10 sample lanes, yielding a throughput of 25-35 min/sample. Capillary IEF separations (including focusing and mobilization) are typically 15-20 min. The mass sensitivity of conventional gel IEF is 36-47 ng for Coomassie staining and 0.5-1.2 ng for silver staining. In capillary IEF, sensitivity will depend on the volume of sample injected; assuming a capillary with a volume of 100 nl is completely filled with sample prior to focusing, the limit of detection will be approximately 1 microgram/ml or 0.1 ng injected. Thus capillary IEF compares favorably with conventional gel IEF in terms of detectivity and analysis time, and has the additional benefit of complete automation of the process including separation and data reduction.

Buffers↗