Biomedical subjects
Publications and source records attributed to M Hu.
Conjunctivitis is a common infection among nursing home residents. The nursing home environment itself may expose residents to an increased risk of infection. Two major sources of infection are the hands of residents and nursing staff, and washing and bathing equipment. Clear guidelines on the prevention of cross-infection are needed in nursing homes.
The dynamic changes of P68 RNA helicases derived from four cell lines were compared on the level of proteins and mRNAs. Of the four cell lines, HeLa and TC3H10 are tumouric while NIH 3T3 and NC3H10 are nontumouric. The TC3H10 is the derivative of NC3H10 induced by 3H-TdR. The growing curves showed that all of them can reach Logarithum phase around 24 hours post-inoculation. The Western blotting showed that the P68 RNA helicases in cells exhibited some regular patterns along with the extended growth of the cell cultures: they appeared as early as 6 hours post-inoculation, reached to the top about 24 hours, and dropped and maintained to low level after then. During a whole passage the bands of P68 RNA helicases were only single in tumour cells but multiple in nontumour cells with moderate changes. RNA slot hybridization resulted in similar quantitative patterns of P68 mRNAs and its proteins in each line. The ATPase activities of P68 RNA helicases purified by McAb-PAb 204 mediated immunoprecipitation were ssRNA-dependent, consistent with the results of P68 RNA helicases reported by others. These results first showed the close relationship between P68 RNA helicase and cell growth on the molecular level, and maybe implied its potential functions in the cell transformation process.
OBJECTIVE: To investigate the internal state of stress distribution in healthy human condyles and to offer some references for application of the temporomandibular joint (TMJ) biomechanics. METHODS: Six male volunteers were selected to perform CT examination of the TMJ with 1.5 mm-thick sections at 1.5 mm intervals. Three dimensional image reconstruction of the joint was performed in the SUN workstation and the CT data were converted into the decimal system. The three dimensional finite element model mesh generation resulted from 1188 elements and 264 nodes in each condyle. Stress calculation was performed with SAP-V program, and the results were converted into mechanical density scalar. During the study, the internal state of stress distribution on each side condyle in every subject was analysed on the basis of loading on the anterior articular surface of the condyle. RESULTS: Stress was concentrated in the anterior articular surface of the condyle and was highest at the loading point. The condylar cortical bone was the main load-bearing area. The level of stress distribution in the cancellous bone of the condyle was very low. Near condylar neck stress was well-distributed on the cortical. The internal state of stress was essentially symmetrical on the same cuts of both side condyles. CONCLUSIONS: The results showed that three dimensional finite element analysis may indicate the internal state of stress distribution in the condyle, suggesting that a combination of the three dimensional finite element methods and the three dimensional imaging technique may be a useful means for diagnosis and treatment of TMJ diseases.
OBJECTIVE: To observe the changes of tissue lithium content and its relationship with glucose metabolism in spontaneous hereditary diabetic Chinese hamsters (SHDCH). METHODS: Twenty diabetic and ten normal Chinese hamsters were paired and separated randomly into four groups: controls (C), diabetics (D), controls treated with lithium carbonate (CT) and diabetics treated with lithium carbonate (DT). The lithium carbonate treatment was administrated with drinking water containing lithium carbonate (0.2 mg/ml). Blood glucose levels were determined at 0, 1, 3, 5, 6th month, and insulin levels at 1, 3, 6th month. The lithium contents in liver, kidney and muscles were determined at the end of 6th month, using wet digestion assay and ICP-AES. Concentrations of fructosamine, lactic acid, GPT, BUN were also evaluated. RESULTS: The data showed that in Group D the lithium levels in hepatic tissue were lower than in Group C (P < 0.05), and lithium contents in kidney and muscle also decreased. In Group DT, the lithium contents in tissues were higher than in Group D (P < 0.05) and similar to Group C. Blood glucose levels and fructosamine concentrations decreased while insulin and lactic acid levels did not alter significantly. GPT and BUN levels did not change in both Group CT and Group DT. CONCLUSIONS: There is lithium deficiency in hepatic, renal and muscular tissues from diabetic Chinese hamsters. Low-dose and six-month-treatments of lithium carbonate can improve tissue lithium deficiency and glucose metabolism, and do not damage liver and kidney functions.
Pre- and post-operative changes of serum glycine-conjugated cholic acid (CG) and 3,5,3'-triiodothyronine (T3) levels were observed in twenty-two patients with cholelithiasis. The increase of the levels of serum CG varied with the patients; the highest levels were seen in patients with cirrhosis. After operation, the levels of serum CG and T3 were decreased significantly in patients without cirrhosis. There was positive correlation between serum CG and T3 (r = 0.4667, P < 0.01). It is indicated that the lowering of serum CG after operation may be related to the lowering of serum T3; the significant increase of serum CG level is useful to the diagnosis of liver cirrhosis, which is more sensitive than Type B ultrasonography or routine examination of liver function.
Overproduction of glucose by the liver is the major cause of fasting hyperglycemia in both insulin-dependent and non-insulin-dependent diabetes mellitus. The distal enzymatic step in the process of glucose output is catalyzed by the glucose-6-phosphatase complex. We show here that 90% partially pancreatectomized diabetic rats have a >5-fold increase in the messenger RNA and a 3-4-fold increase in the protein level of the catalytic subunit of glucose-6-phosphatase in the liver. Normalization of the plasma glucose concentration in diabetic rats with either insulin or the glycosuric agent phlorizin normalized the hepatic glucose-6-phosphatase messenger RNA and protein within approximately 8 h. Conversely, phlorizin failed to decrease hepatic glucose-6-phosphatase gene expression in diabetic rats when the fall in the plasma glucose concentration was prevented by glucose infusion. These data indicate that in vivo gene expression of glucose-6-phosphatase in the diabetic liver is regulated by glucose independently from insulin, and thus prolonged hyperglycemia may result in overproduction of glucose via increased expression of this protein.
The membrane-disrupting activity of 15 triterpenoid saponins, obtained from Chinese plants of the genus Aralia, was investigated using phosphatidylcholine liposomes with and without cholesterol. The permeability of the membrane was examined by monitoring the induced fluorescent dye release from the liposome. On the basis of the obtained results, the structure-activity relationship among glucuronides of oleanolic acid was discussed. This takes into account particularly the variation in the carboxyl function. Namely, the saponins could induce a permeability change on liposomal membrane without cholesterol when they are glycosylated at both C-3 and C-28 of the oleanolic acid. There also exists a great similarity in the time-course curves for dye-release within such saponins, reflecting their similar action with the lipid bilayer membrane. The saponins glycosylated only at C-3 could also exhibit the same activity with somewhat different action profiles when the glucuronic acid is esterified, while those with the free glucuronic acid required cholesterol in the liposomes to induce permeability change thereof.
RATIONALE AND OBJECTIVES: We evaluated pathologic correlations of pulmonary parenchymal manifestations surrounding small peripheral masses and their usefulness in differentiating small peripheral bronchogenic carcinomas from tuberculomas. METHODS: We evaluated 29 resected lobe specimens with 1.5- to 3.5-cm solitary pulmonary masses, including 24 carcinomas and five tuberculomas. These specimens were prospectively studied with preoperative chest radiographs, postoperative specimen radiographs, 10- to 15-microns-thick wholemount sections, and 5-microns-thick slices. A total of 100 chest X-rays and conventional tomography scans of 1- to 3-cm peripheral pulmonary masses, including 60 carcinomas and 40 tuberculomas, were retrospectively reviewed and analyzed. RESULTS: The pulmonary parenchymal manifestations surrounding the masses presented as small infiltrates and nodular protrusions, thickened strands, and "double track" shadows, which extended from the proximal margin of five tuberculomas (100%, 5 of 5) and from the distal margin of 17 carcinomas (71%, 17 of 24). These pulmonary changes represented caseous material spreading from tuberculomas into the proximal bronchus and alveolar inflammatory exudation distal to the carcinomas. The proximal pulmonary manifestations were significantly more frequent in tuberculomas than in carcinomas (p < .01), whereas the distal pulmonary manifestations were more often found in carcinomas than in tuberculomas (p < .01). CONCLUSION: The radiologic findings of the pulmonary parenchymal manifestations proximal or distal to the masses may be valuable radiologic signs for distinguishing between tuberculomas and small peripheral bronchogenic carcinomas, even though there is still considerable crossover between the two disease populations in the findings.
The mechanisms of apical (AP) uptake of cephalexin (CEPH) and loracarbef (LOR) in the absence or presence of an (extemally imposed) proton gradient were determined using well-stirred diffusion chambers that minimize the effects of the unstirred water layer. The results indicated that, compared to AP uptake in the presence of an imposed proton gradient, AP uptake in the absence of an imposed proton gradient had higher K(m) values and lower Jmax values. Furthermore, when inhibition studies were performed in the absence of a proton gradient, only natural peptides were effective, whereas the peptide analogs (e.g., enalapril) were not. In addition to the effects of concentration and competitive inhibitors, the results also indicated that (1) the AP uptake of both drugs was decreased more than 60% by FCCP, regardless of whether the proton gradient was present or absent; (2) effects of protein kinase C promoter were dependent upon the presence of a proton gradient; and (3) AP uptake in the presence of an imposed proton gradient was not affected by feeding restriction, whereas AP uptake in the absence of an imposed proton gradient was. These results showed for the first time that two substrates with similar AP uptake characteristics in the presence of an imposed proton gradient may not share those characteristics in the absence of an imposed proton gradient. Taken together, these results suggest that the AP uptake component that functions in the absence of an imposed proton gradient is distinctly different from the one that functions in the presence of an imposed proton gradient. Data generated from the present study and those in the literature lend support to the hypothesis that this distinctive component represents the second binding site on the AP peptide transporter. However, an alternative hypothesis that there are two AP peptide transporters remains to be disapproved.
PURPOSE: To develop Caco-2 cell derivatives expressing high levels of human cytochrome P450 drug metabolizing enzymes. METHODS: The cDNAs for two cytochrome P450 forms, CYP2A6 and CYP3A4, were introduced into an extrachromosomal vector under control of the cytomegalovirus early intermediate promoter. Vector-bearing cells were selected via resistance to hygromycin B. RESULTS: Transfected cells exhibited high levels of cDNA-derived protein as measured by Western blot, spectrophotometric P450 determination and/or cytochrome P450 form-selective enzyme assay. CYP3A4 and CYP2A6 catalytic activities were about 100 fold higher than in control cells. cDNA-expressing cells were found to form tight monolayers and were suitable for study of xenobiotic transport and metabolism. The permeabilities of cephalexin, phenylalanine, mannitol and propranolol across transfected monolayers were found to be similar to those across untransfected monolayers. The appropriate transfected monolayers metabolized the CYP2A6 substrate coumarin and the CYP3A4 substrates testosterone and nifedipine. CONCLUSIONS: A Caco-2 cell system to simultaneously study drug transport and metabolism has been developed.
RATIONALE AND OBJECTIVES: By performing pulmonary specimen angiographies, the authors attempted to determine the pathologic correlations of the vascular-related radiologic manifestations within, at the edge of, and adjacent to the small solitary pulmonary masses, and to evaluate their usefulness in differentiating small bronchogenic carcinomas from tuberculomas. METHODS: A total of 29 resected lobe specimens with 1.5- to 3.5-cm solitary pulmonary masses, including 24 carcinomas and 5 tuberculomas, were studied prospectively with preoperative radiographs, postoperative specimen arteriographies (in 19 carcinomas and 5 tuberculomas), and venographies (in 5 carcinomas), 10- to 15 micrograms-thick whole-mount sections, and 5-micrograms-thick slices for the examination of angiographic-pathologic correlation. Another series of chest radiographs and conventional tomographs of 100 patients with 1- to 3-cm peripheral pulmonary masses, including 60 carcinomas and 40 tuberculomas, were reviewed retrospectively and analyzed with the chi-square test. RESULTS: Specimen angiographies showed the intralesion avascularity, small arterial speculation, and lobulation or notch at the mass margin with arterial compression, as well as vascular convergence to the mass, in both carcinoma and tuberculoma groups. The irregular arterial wall (79.2%) and venous dilation distal to the mass (100%) were found in the carcinoma group only. Microscopically, arterial or venous fibrous hyperplasia was observed in both carcinomas and tuberculomas, whereas the arterial erosion by tumor tissue and tumor emboli within the vessels were found in carcinomas only. The retrospective review of the 100 patients showed that two radiologic signs of the vascular convergence to the mass and the vascular dilation distal to the mass occurred at similar frequencies (12%-13%) between the carcinoma and tuberculoma groups. CONCLUSIONS: In addition to compression of vessels by tumor and vessel occlusion by tumor embolus, pulmonary vascular fibrotic hyperplasia can cause intramass avascularity. Small vessels running vertically into or from the mass margin can construct the spiculation sign of the tuberculomas. Any evidence of pulmonary vascular irregularity will indicate a bronchogenic carcinoma. The vascular convergence to the mass and the vascular dilation distal to the mass are not specific radiologic signs for small solitary bronchogenic carcinomas.
Hepatic transcription of insulin-like growth factor-binding protein-1 (IGFBP-1) is enhanced in hypophysectomized (hypox) rats and can be rapidly down-regulated by GH administration. Here we examined the effect of insulin on IGFBP-1 messenger RNA abundance in hypox rats and the effects of insulin and GH on IGFBP-1/chloramphenicol acetyltransferase (CAT) reporter plasmids transiently transfected into isolated hepatocytes from pituitary-intact and hypox rats. Unlike GH, administration of insulin to hypox rats in doses of 10 or 50 micrograms/100 g BW had no effect on hepatic IGFBP-1 messenger RNA abundance. Insulin at 10(-7) M resulted in a 42.1 +/- 9.8% suppression of CAT activity in hepatocytes from pituitary-intact animals transfected with a CAT reporter plasmid containing 1671 bp of the 5'-flanking region of the rat IGFBP-1 gene. In the same assay, GH at a concentration of 2.3 x 10(-8) M significantly reduced CAT activity. In contrast, insulin had no effect on CAT activity in hepatocytes from hypox rats, whereas GH resulted in comparable suppression of CAT activity in hepatocytes from hypox rats and pituitary-intact rats, 13.6 +/- 2.3% vs. 18.2 +/- 3.2%. Deletional analysis and mobility shift assays were used to identify the GH-responsive regions in the IGFBP-1 gene. GH suppression of CAT activity was lost when the IGFBP-1 5'-flanking region was deleted down to -277 bp, whereas insulin suppression was retained for all but the smallest fragment of the IGFBP-1 gene. Mobility shift assays were used to compare nuclear extracts from sham-operated, hypox, and GH-treated hypox rats. When hepatic nuclear extracts from hypox rats were incubated with the -277 to -82 and the -556 to -368 bp fragments, retarded bands were apparent that were not present in the extracts from sham-operated rats. GH treatment of hypox rats 15 or 30 min before death completely normalized the retardation pattern seen with the -277 to -82 bp fragment, but did not affect the pattern seen with the -556 to -368 bp fragment. A 20-bp fragment corresponding to the previously identified insulin response element, -108 to -89 bp, was also analyzed. An additional retarded band, not seen with nuclear extracts from sham-operated rats, was apparent when nuclear extracts of hypox rats or GH-treated hypox rats were used. These data provide the first in vitro evidence that GH directly regulates transcription of IGFBP-1 expression. In addition, our findings suggest that GH modulates insulin regulation of IGFBP-1 transcription, possibly by altering the milieu of trans-acting factors that interact with both the insulin response element and distinct upstream sites.
Although the kinetic characteristics of hepatic glucokinase (GK) suggest its potential role as the hepatic "glucose sensor," its impact on the regulation of in vivo hepatic glucose production (HGP) is still controversial. Since decreased GK activity has been linked to experimental and human diabetes, we examined whether a moderate and transient inhibition of GK activity diminishes the ability of hyperglycemia to suppress HGP. We first determined the concentration of the competitive inhibitor, glucosamine (GlcN), which decreases hepatic GK activity by approximately 60% in vitro. GlcN was then infused into conscious rats to achieve a similar inhibition of the in vivo GK activity (plasma GlcN levels = approximately 2 mmol/l; rats infused with saline served as control, n = 20). To maintain equal plasma insulin and glucagon concentrations throughout the studies, somatostatin and insulin (basal replacement) were infused for 4 h. [3-(3H)]-glucose and [U-(14C)]-lactate were infused to measure HGP, gluconeogenesis, and glucose cycling (GC) during 2 h of euglycemia (glucose approximately 8 mmol/l) followed by 2 h of hyperglycemia (glucose approximately 18 mmol/l). Our results support the notion that hepatic GK activity is indeed decreased by GlcN in vivo. In fact, in response to hyperglycemia the "direct" pathway of hepatic glucose-6-phosphate (G-6-P) formation was approximately 40% lower with GlcN compared with saline infusion (37 +/- 3 vs. 63 +/- 3%; P < 0.001). Furthermore, while hyperglycemia stimulated GC by approximately 2.5-fold during saline infusion (from 3.0 +/- 0.6 to 7.7 +/- 1.4 mg.kg-1.min-1, P < 0.001, euglycemia vs. hyperglycemia), this increase was blunted in the presence of GlcN (4.6 +/- 0.6 mg.kg-1.min-1, P = NS). Finally, in the presence of GlcN, the hepatic concentration of G-6-P was decreased by approximately 40% compared with saline (234 +/- 38 and 390 +/- 24 nmol/g, P < 0.01). During the euglycemic studies, HGP was similar (12.6 +/- 0.6 and 11.3 +/- 0.2 mg .kg-1.min-1 with GlcN or saline infusion, respectively). However, while hyperglycemia per se suppressed HGP by approximately 65%, HGP was inhibited by approximately 38% and it was approximately twofold higher than in the saline-infused rats (7.8 +/- 0.8 and 4.0 +/- 0.3 mg.kg-1.min-1, P < 0.01) in the presence of GlcN-induced inhibition of hepatic GK. This increase in HGP was largely accounted for by the decreased inhibition of hepatic net glycogenolysis by hyperglycemia (3.3 +/- 0.8 and 1.1 +/- 0.3 mg.kg-1.min-1 with GlcN or saline infusion, respectively, P < 0.01). We conclude that intact GK activity is required for the normal suppression of HGP by hyperglycemia and its impairment may contribute to increased HGP in experimental and human diabetes.
Prolonged glucosamine (GlcN) infusion increases the skeletal muscle hexosamine concentration and induces peripheral insulin resistance in conscious rats. IGF-1 and insulin share common steps in signal transduction, and the action of IGF-1 on carbohydrate metabolism is preserved in certain insulin-resistant states. In our study, we attempted to delineate whether increased GlcN availability also impairs the effects of IGF-1 on glucose uptake (Rd), glycolysis, and glycogen synthesis. We performed euglycemic IGF-1 (5 and 15 microg x kg(-1) x min(-1)) and insulin (3 and 18 mU mg x kg(-1) x min(-1)) clamp studies at 0-2 h and 5-7 h in conscious rats (n = 44) during saline or GlcN infusions. GlcN infusion raised plasma GlcN levels to approximately 2.0 mmol/l and skeletal muscle uridinediphospho-n-acetylglucosamine to 80-150 nmol/g (approximately three- to fivefold over basal). During physiological hyperinsulinemia (3 mU x kg(-1) x min(-1), plasma insulin approximately 50 microU/ml), GlcN infusion caused comparable decreases in Rd (15.7 +/- 1.0 [5-7 h] vs. 21.7 +/- 2.3 [0-2 h] mg x kg(-1) x min(-1); P < 0.01) and glycogen synthesis (5.4 +/- 0.5 [5-7 h] vs. 10.4 +/- 1.9 [0-2 h] mg x kg(-1) x min(-1); P < 0.005). Furthermore, GlcN markedly decreased Rd by 7.8 +/- 1.2 mg x kg(-1) x min(-1) (18.7 +/- 0.7 [5-7 h] vs. 26.5 +/- 1.3 [0-2 h] mg x kg(-1) x min(-1); P < 0.001 vs. control) during IGF-1 (5 microg x kg(-1) x min(-1)) clamp studies. This decline was associated with a 26% decrease in the steady-state concentration of skeletal muscle Glc-6-P (286 +/- 45 vs. 386 +/- 36 nmol/g; P < 0.01) and was primarily caused by impaired glycogen synthesis (6.7 +/- 0.5 [5-7 h] vs. 13.9 +/- 0.9 [0-2 h] mg x kg(-1) x min(-1); P < 0.005). The effects of GlcN infusion on glucose disposal (percentage decrease in Rd) were correlated (r2 = 0.803; P < 0.01) with the skeletal muscle concentration of UDP-GlcNAc. To investigate whether IGF-1 can overcome GlcN-induced insulin resistance, GlcN and insulin (18 mU x kg(-1) x min(-1)) were infused for 7 h during euglycemic clamps, and IGF-1 (15 microg x kg(-1) x min(-1)) was superimposed during the final 2 h. GlcN infusion induced severe impairment of insulin action on Rd (39.4 +/- 3.2 [4-5 h] vs. 49.8 +/- 3.6 [1-2 h] mg x kg(-1) x min(-1); P < 0.05), which the addition of IGF-1 failed to improve (35.9 +/- 2.3 [6-7 h] vs. 39.4 +/- 3.2 [4-5 h] mg x kg(-1) x min(-1); P > 0.1). In summary, GlcN induced severe resistance to the actions of both insulin and IGF-1 on glucose uptake and glycogen synthesis, and IGF-1 was unable to overcome GlcN-induced insulin resistance. Thus, it is likely that GlcN causes peripheral insulin resistance acting at a site common to both IGF-1 and insulin signaling pathways.
In order to probe relationship of inhibition activity of platelet aggregation and RGD conformation beneficial to binding in Echistatin, we used the site-directed mutation technique to install another RGD sequence into one of irregular loops retaining a degree of conformational flexibility and substituting Leu-14, Lys-15, Glu-16 of (Leu-28) Echistatin. The mutant (Arg-14, Gly-15, Asp-16, Leu-28) Echistatin did not lose its inhibition activity of platelet aggregation; however, it showed at least as high activity as (Leu-28) Echistatin, or even a little higher than (Leu-28) Echistatin. This suggested that both RGD sequences inserted in one loop with a degree of conformational flexibility. The original RGD (Arg-24, Gly-25, Asp-26) motif projecting significantly from the surface of the scaffold or core might contribute synergistically to the function of inhibiting platelet aggregation induced by 10 mumol/ L ADP (final concentration). These results are useful in the elucidation of the relationship of structure and function of Echistatin-like disintegrins and GPIIb/IIIa-like integrins.
In order to explore the significance of HBV in the pathogenesis of cholangiocarcinoma at molecular level, HBV DNA, X gene, pre-S gene, S gene and C gene in 40 cases of primary intrahepatic cholangiocarcinoma and its surrounding tissue were detected by in situ hybridization technique. The results showed that 33 cases (82.5%) were positive for HBV DNA, while 31 (77.5%), 26 (65.0%), 24 (60.0%) and 27 (67.5%) cases were positive for X gene, pre-S gene, S gene and C gene, respectively. The results of this study suggest that there exists a close relationship between human primary intrahepatic cholangiocarcinoma and HBV chronic persistent infection. The expression of X gene might play an important role in the pathogenesis of the primary intrahepatic cholangiocarcinoma.
OBJECTIVE: This study was designed to test the hypothesis that inflammatory cells deposited on the surface of implanted intraocular lens stimulate the proliferation of residual lens epithelial cells. METHODS: Immunocytochemical ABC methods with purified anti-human Fos protein serum antibody was used to stain the cultured rabbit lens epithelial cells incubated with rabbit macrophages and macrophage-conditioned medium (MCM). RESULTS: The lens epithelial cell growth was faster in the cultures with macrophages and MCM than in the controls. Fos protein positive staining was found in the nuclei of epithelial cells cultured with macrophages for 4 hours, and of the cells with MCM for one hour; whereas the staining was negative in the cells of control cultures. CONCLUSION: Macrophages promote c-fos oncogene expression in the lens epithelial cells, that might be mediated by bioactive factors secreted by macrophages.
The effects of ammonia on cultured fetal rat neurons and the possible relation between morphologic changes of neurons and the pathogenesis of hepatic encephalopathy were studied on dissociated fetal rat neuronal cultures, using light microscopy, transmission electron microscopy and immunohistochemistry methods. The neurons exhibited cellular swelling, chromatolysis, vacuolization and granulation, followed by segmental enlargement and fragmentation of cellular processes, detachment of neurons with pyknotic nuclei. Electron microscopic examination displayed dilation of mitochondria and endoplasmic reticulum, degranulation of rough endoplasmic reticulum, accumulation of dense bodies together with swelling of the process with loss of neurofilaments. The expression of neurofilament and synaptophysin became weak and even negative. The data therefore suggests that ammonia may exert a toxic effect on cultured neurons, disturbing their normal function and facilitating the development of hepatic encephalopathy.