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Biomedical subjects

M Li

Publications and source records attributed to M Li.

At least 901 records · Page 50Linked to original sources
PubMed1995

Parathyroid hormone monotherapy and cotherapy with antiresorptive agents restore vertebral bone mass and strength in aged ovariectomized rats.

Previous studies have shown that parathyroid hormone (PTH) monotherapy and cotherapy with estrogen or risedronate augment vertebral bone mass and bone strength in young, ovariectomized (OVX) rats. The current study was designed to determine whether PTH has similar bone anabolic effects in aged OVX rats at a much later stage of estrogen depletion. Female Sprague Dawley rats were subjected to sham surgery or bilateral ovariectomy at three months of age and maintained untreated for one year after surgery to allow for the development of vertebral osteopenia in OVX rats. Groups of baseline control and OVX rats were sacrificed at the end of this pretreatment period. The remaining OVX rats were then treated for ten weeks with vehicle, antiresorptive agents alone (estrogen, risedronate, or calcitonin), or PTH alone. Other groups of OVX rats were treated concurrently with PTH and each of the antiresorptive agents. The first and fourth lumbar vertebral bodies were processed undecalcified for quantitative bone histomorphometry and biomechanical testing, respectively. As expected, bone mass and compressive strength were decreased in the lumbar vertebral body of baseline OVX rats compared to baseline control rats. This bone loss was associated with decreases in trabecular number and width and an increase in trabecular separation. Treatment with estrogen, risedronate, or calcitonin alone failed to reverse the changes in bone mass, structure, and strength induced by ovariectomy. In contrast, treatment of OVX rats with PTH alone restored vertebral cancellous bone volume and ash density to the level of vehicle-treated control rats and increased vertebral maximum load, stress, and normalized load to well above this level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Expression and regulation of glycosyltransferases for N-glycosyl oligosaccharides in fresh human surgical and murine tissues and cultured cell lines.

1. Mammalian membrane and serum proteins are glycosylated by the addition of heterogeneous N-linked oligosaccharides. It has been widely speculated that oligosaccharide diversity is achieved by corresponding heterogeneity of expression of the glycosyltransferases that are responsible for oligosaccharide synthesis. 2. We surveyed mRNA levels of three sequentially acting glycosyltransferases, N-acetylglucosaminyl-transferase I, beta 1,4-galactosyltransferase and alpha 2,6-sialyltransferase, in 11 human tissues and confirmed the expected variations. 3. The size heterogeneity of alpha 2,6-sialytransferase transcripts reported in rat tissues was evident neither in the human tissue survey nor in a panel of murine RNAs. Tissue distributions of alternative terminal sialyltransferases, alpha 2,6-sialyltransferase and alpha 2,3-sialyltransferase, were distinct. 4. Relative glycosyltransferase mRNA levels in four transformed human cell lines cultured in vitro did not fully reflect levels in the corresponding human tissues. 5. Expression of alpha 2,6-sialyltransferase mRNA was approximately 2.6-fold greater in adenocarcinomatous than in normal human colon, and beta 1,4-galactosyltransferase expression was approximately 1.8-fold greater in normal than in adenocarcinomatous colon. 6. n-Butyrate (0.003-0.005 mol/l), a short-chain fatty acid that is produced by colonic bacterial fermentation, caused approximately 80% inhibition of alpha 2,6-sialyltransferase, approximately 2.5-fold induction of beta 1,4-galactosyltransferase and approximately 6-fold induction of N-acetylglucosaminyltransferase mRNAs in T84 (colonic) cells. The effects on alpha 2,6-sialyltransferase and beta 1,4-galactosyltransferase were near maximal by 6h, but induction of N-acetylglucosaminyltransferase was fully apparent only after exposure for 24 h.

Adenocarcinoma↗
PubMed1995

Evidence for in vivo but not in vitro expression of a Borrelia burgdorferi outer surface protein F (OspF) homologue.

Protein export signals from the low-passage 297 strain of Borrelia burgdorferi were cloned as fusions with an Escherichia coli alkaline phosphatase (PhoA) reporter lacking a signal sequence. One PhoA+ clone (BbK2.10-PhoA) was derived from a borrelial lipoprotein. Although the polypeptide encoded by the full-length bbk2.10 gene had 76% similarity and 56% identity to outer surface protein F (OspF) from B. burgdorferi strain N40, antibodies directed against recombinant forms of the two proteins revealed that they were not cross-reactive. The nucleotide sequences of bbk2.10 and ospF from the N40 and 297 strains, respectively, were determined to confirm that the N40 and 297 strains each contained both genes. Southern blot analysis revealed that bbk2.10 is a single-copy gene and that the B. burgdorferi strain 297 and N40 genomes appeared to contain one other gene more closely related to ospF than bbk2.10. It was particularly noteworthy that ospF, but not bbk2.10, was expressed in vitro while B. burgdorferi-infected mice generated antibodies reactive with both lipoproteins. To help confirm that the BbK2.10-reactive antibodies produced by the B. burgdorferi-infected mice were specific for that protein, a second gene, bbk2.11, which hybridized with the ospF probe was cloned; the corresponding polypeptide reacted strongly with OspF antisera but failed to react with BbK2.10-specific antisera. Taken together, these data demonstrate that BbK2.10, BbK2.11, and OspF comprise a B. burgdorferi lipoprotein family and that at least one member (BbK2.10) appears to be expressed only during infection.

Amino Acid Sequence↗
PubMed1995

Benzyl alcohol allergy.

A 63 year old woman presented with a 3 year history of vulval lichen sclerosus et atrophicus and vulval dermatitis resistant to multiple topical therapies. She was patch test positive to 5% benzyl alcohol which is a widely used preservative in topical creams and a component in balsam of Peru.

Anti-Infective Agents, Local↗
PubMed1995

Long-term ouabain administration does not alter blood pressure in conscious Sprague-Dawley rats.

1. We tested the ability of ouabain to cause chronic hypertension by continuously infusing ouabain for 28 days (miniosmotic pump implantation; i.p.). The blood pressure and metabolic effects of sham (150 mmol/L NaCl; n = 12) or ouabain infusion (10 micrograms/kg per day; n = 14; 100 micrograms/kg per day; n = 14) were examined in conscious Sprague-Dawley rats. 2. Plasma ouabain concentrations measured after 28 days of ouabain infusion were as follows: sham, not detectable (n = 11); ouabain 10 micrograms/kg per day, 0.60 +/- 0.07 nmol/L (n = 14); and ouabain 100 micrograms/kg per day, 7.17 +/- 0.57 nmol/L (n = 14; P < 0.001). 3. Sham or ouabain infusion did not alter food intake, bodyweight, water intake or urine output in conscious rats. 4. Blood pressure was not altered by sham treatment. Ouabain at 10 micrograms/kg per day or 100 micrograms/kg per day did not produce consistent rises in blood pressure. Ouabain at 10 micrograms/kg per day increased blood pressure on treatment day 12 only (+6 mmHg; P < 0.05), while at 100 micrograms/kg per day blood pressure increased on treatment days 16 (+9 mmHg; P < 0.05) and day 18 (+8 mmHg; P < 0.05) only. There was no significant difference in blood pressure between sham and ouabain groups. 5. Renal blood flow was decreased in rats infused with ouabain at 10 micrograms/kg per day (2.0 +/- 0.3 mL/min per 100 g bodyweight; n = 5; P < 0.01) and 100 micrograms/kg per day (2.2 +/- 0.4 mL/min per 100 g bodyweight; n = 7; P < 0.05) compared with sham treatment (3.5 +/- 0.2 mL/min per 100 g bodyweight; n = 6). Renal vascular resistance was increased in rats treated with ouabain at 10 micrograms/kg per day (65.5 +/- 12.6 mmHg/mL per min per 100 g bodyweight; n = 5; P < 0.01) and 100 micrograms/kg per day (66.0 +/- 15.6 mmHg/mL per min per 100 g bodyweight; n = 7; P < 0.05) compared with sham treatment (32.6 +/- 2.5 mmHg/mL per min per 100 g bodyweight; n = 6). 6. High plasma concentrations of ouabain do not cause consistent increases in blood pressure in conscious Sprague-Dawley rats.

Animals↗
PubMed1995

Investigation on breastfeeding and lactational amenorrhoeic women in mountainous areas of Pengxian County, Southwest China.

OBJECTIVE: To determine the distributions of the duration of postpartum breastfeeding, amenorrhoea, and contraceptive use, a community-based epidemiological investigation was carried out in Pengxian County, Southwest China in March 1992. METHODS: 1,040 women who had given live births during the reference period were interviewed. A current-status life table analysis was used. RESULTS: At 1 month postpartum, 100% infants were breastfed, at 6 months 95%, and at 12 months 82%. The level of amenorrhoea at 1 month postpartum was 90%, at 3 months 74%, at 6 months 62%, and at 12 months 36%. Contraceptive use was initiated at the second month postpartum with 19% of users, at 6 months 48%, and at 12 months 91%. CONCLUSION: The results indicate that at population level advising women to begin using contraceptives in 3 months postpartum is fairly reasonable, and the non-medicated IUD is recommended to be the first choice for the lactating women.

Adult↗
PubMed1995

Molecular detection and serotypic analysis of enterovirus RNA in archival specimens from patients with acute myocarditis.

OBJECTIVE: To determine whether enterovirus RNA can be demonstrated in archival necropsy material in acute myocarditis. DESIGN: Analysis of paraffin embedded myocardial tissue from cases of acute myocarditis. SETTING: University virology department. METHODS: Extraction of RNA from tissue followed by polymerase chain reaction (PCR) and DNA sequence analysis. PATIENTS: Six patients with histologically proven myocarditis and eight controls. RESULTS: Enterovirus RNA was identified in 5 of 6 patients with myocarditis and in none of the controls. The nucleotide sequences of the PCR products showed greatest similarity to group B coxsackieviruses, particularly coxsackievirus B3. CONCLUSION: This study indicates that archival tissue samples, even histologically stained tissue sections, can be used to study the role of enteroviruses in myocardial disease using molecular detection techniques. If a predominant role for coxsackievirus B3 in myocarditis is confirmed by further study, this may have implications for the development of a specific vaccine.

Acute Disease↗
PubMed1995

Present systems and future needs for risk assessments of biologicals: the perspective of the regulator in the People's Republic of China.

Regulation of veterinary biologicals in the People's Republic of China is governed by the Animal Drug Administration Regulations issued by the State Council in 1987. These regulations authorize the Ministry of Agriculture to prescribe requirements governing the production and marketing of veterinary biologicals shipped into, within or from China. The goal of the veterinary biologicals programme is to ensure that all veterinary biological products are pure, safe, potent and effective. The programme is based on review, licensing, inspection and post-licensing testing. Risk assessment procedures and requirements for biotechnology-derived veterinary biologicals have been established. China needs international harmonization of trade in veterinary biologicals and will make a great contribution in this field.

Animals↗
PubMed1995

Abrogation of the allelic exclusion in a T cell receptor beta chain gene transgenic mouse strain.

The expression of endogenous T cell receptor (TcR) beta chains in a TcR beta chain gene transgenic mouse (TGM) strain was examined. Unlike many other TGM strains reported, a considerable proportion of T cells from the thymus and spleen as well as organ cultured fetal thymus from our TGM express endogenous TCR beta chains on their surface. Compatible with this was the elucidation of VDJ rearrangement of endogenous beta chain genes by PCR. Three color flow cytometric analysis of thymus cell subpopulations revealed that the expression levels of both endogenous and transgenic TcR beta genes are regulated in a maturational stage specific manner. Splenic T cells contained a several fold higher percentage of endogenous TcR beta positive cells than thymus cells, suggesting a role of TcR on T cell peripherization. V beta 6 positive cells were deleted in the TGM carrying minor lymphocyte stimulating (Mls)-la antigen, indicating that the endogenous TcR beta is functional in terms of transmitting a signal for clonal deletion.

Alleles↗
PubMed1995

[Liver-protecting and alanine aminotransferase lowering actions of hongning gantai].

Hongning Gantai has a remarkable counteraction on the elevation of ALT activity of mice and rats induced by chemical damages with CCl4 and D-Gal. It can decrease the BSP-retention. The result of pathologic examination indicates that Hongning Gantai can alleviate liver damages of mice and rats and thus has liver-protecting and ALT-lowering actions.

Alanine Transaminase↗
PubMed1995

[An approach to determining the effect on salivary amylase by green tea extract].

The inhibition effect of three Chinese tea and a kind of acid tea without fluoride to human salivary amylase were studied. The inhibited ability of polyphenols and fluoride were further studied, simultaneously, the tea: saliva ratio were also tested in vitro. The results indicated that the inhibition effect was in this order: acid tea, Ulong tea, longjing, huacha. The polyphenols play important role in the inhibition of salivary amylase, the optimal ratio between tea and saliva was 0.6:1.

Amylases↗
PubMed1995

Endotoxin-induced liver injury and changes in the levels of plasma tumor necrosis factor-alpha and interleukin-6 in rabbits.

ELISA was employed to detect changes in plasma TNF-alpha and IL-6 level in rabbits having endotoxin-induced generalized Shwartzman reaction. Liver injury was assessed by the increase of serum ALT and hepatic histopathologic changes. The results showed that plasma TNF-alpha and IL-6 levels increased remarkably 12h after intravenous injection of endotoxin twice at a 24h interval, and these changes corresponded with the degree of liver injury. Coinjection of dexamethasone and endotoxin partly prevented the elevation of TNF-alpha and IL-6 levels and reduced liver injury. These results indicated that TNF-alpha and IL-6 were involved in endotoxin-induced liver injury.

Animals↗
PubMed1995

[Protective effects of methanolic extract of Oenanthe stolonifera (Roxb.) Wall. ex DC. on myocardial injury induced by ischemia and reperfusion in rats].

The methanolic extract Oenanthe stoloni fera iv, pretreatment can significantly prevent the arrhythmias induced by myocardial ischemia and reduce the myocardial infarct size in rats. It can also markedly prevent myocardial ischemia and reperfusion-induced arrhythmias. In addition, the methanolic extract of Oenanthe stoloni fera (100 mg/kg i.v.) helps significantly to decrease the MDA content and preserve the SOD activity in plasma.

Animals↗
PubMed1995

[The study of platinum concentration in retroperitoneal lymph nodes after intraperitoneal carboplatin in ovarian tumors].

Twenty three patients with ovarian tumors were given intraperitoneal carboplatin (300 mg/m2) at different times before laparotomy and retroperitoneal lymphadenectomy. Total platinum (Pt) concentrations in the nodes, the peritoneum and other tissues were measured by flameless atomic absorption spectrometry. Histologic examinations were carried out for the nodes. In addition, Total platinum concentration of the plasma was determined in 3 cases. Peak Pt concentration in retroperitoneal nodes reached at 12 th hour after instillation, and the peak value was 13.38 +/- 1.85-21.57 +/- 7.80 micrograms/g, its AUC0-24th was 216.8 +/- 9.2-246.4 +/- 32.9 micrograms.h/g. AUC 0-24th for the fatty and connective tissues around th e pelvic nodes was 115.6 +/- 40.9 micrograms.h/g; it was significantly lower than AUC 0-24th for the nodes. AUC 0-24th for the pelvic peritoneum was 1 351.3 +/- 696.5 micrograms.h/g. Peak concentrations in the plasma were reached at the second hour after intraperitoneal carboplatin. Its peak value and AUC 0-24th were 6.7 +/- 1.0 microgram/L and 61.5 +/- 2.4 micrograms.h/L respectively. They were obviously lower than those for the nodes. These results indicate that after intraperitoneal carboplatin concentrations of the drug are higher in the retroperitoneal nodes than in the blood. Post chemotherapeutic histological cytodegeneration is found in the lymph nodes in some cases.

Adult↗
PubMed1995

[Fibrous structure of connective tissue of normal human lamina cribrosa].

Fibrous components and structural morphology of the connective tissue of the lamina cribrosa obtained from 35 normal human autopsy eyes were examined by histochemical staining, transmission electron microscopic and computer-assistant image analytical techniques. Principles of biomechanics were used onto the lamina cribrosa in characterizing its structural and mechanical properties, and in investigating its damage forms, intermediary role between intraocular pressure and optic nerve damage, and intervening factors. We came to the following conclusions: The laminar bundles contain all the three kinds of fibers and behave in such triplex properties as elasticity, plasticity and stiffness. The ellipse shaped transverse section of the lamina cribrosa with the long axis at the vertical meridian, the quadrant variations in the course and density of laminar bundles, and the interindividual variations in the thickness of the lamina cribrosa are responsible for the damage-resistant ability of lamina cribrosa. The intraocular pressure exerts effects upon the lamina cribrosa through two ways, and the damage of the lamina cribrosa is the intermediate link between the insults of the intraocular pressure and the optic nerve damage.

Adult↗