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Biomedical subjects

B He

Publications and source records attributed to B He.

At least 235 records · Page 13Linked to original sources
PubMed1995

[The effect of transforming growth factor-beta on collagen expression by human embryonic fibroblasts].

Transforming growth factor-beta (TGF-beta) is a cytokine with diverse biological activity. It can regulate the metabolic function of extracellular matrix (ECM) and play an important role in the development of pulmonary fibrosis. Collagen are major ECM components that are responsible for normal lung structure and function. Collagen accumulation is a major feature of pulmonary fibrosis. In order to study the mechanism of pulmonary fibrosis, we examined the effects of TGF-beta on the production, mRNA expression of type I collagen and type IV collagen by cultures of human embryonic lung fibroblasts. The results indicated that TGF-beta can induce collagen formation and type I collagen, type IV collagen mRNA expression without affecting cell proliferation. We concluded that TGF-beta plays a role in collagen accumulation of pulmonary fibrosis and the changes in collagen production appear to be mediated on collagen mRNA level.

Collagen↗
PubMed1994

Synthesis of prostaglandin H synthase-2 by human alveolar macrophages in response to lipopolysaccharide is inhibited by decreased cell oxidant tone.

We previously demonstrated that lipopolysaccharide (LPS) increases expression of the prostaglandin H synthase-2 (PGHS-2) gene (Hempel, S.L., Monick, M.M., and Hunninghake, G.W. (1994) J. Clin. Invest. 93, 391-396). In this study, the expression of the PGHS-2 gene in response to changes in cell oxidant tone was studied. During LPS exposure, inhibition of synthesis of the free radical, NO., resulted in a small decrease in prostaglandin E2 synthesis that did not reach statistical significance. There was no effect on enzyme mass or mRNA. In contrast, incubation of alveolar macrophages in the presence of LPS plus the antioxidant pyrrolidine dithiocarbamate, the spin trap 5,5-dimethyl-1-pyrroline-N-oxide, or hypoxia, resulted in near complete inhibition of prostaglandin E2 synthesis, PGHS-2 enzyme synthesis, and gene transcription of PGHS-2 mRNA. There was no evidence of cytotoxicity. These results demonstrate that synthesis of PGHS-2 in response to LPS is inhibited by agents that decrease cell oxidant tone.

Amino Acid Oxidoreductases↗
PubMed1994

Determination of 7 alpha-hydroxy-4-cholesten-3-one level in plasma using isotope-dilution mass spectrometry and monitoring its circadian rhythm in human as an index of bile acid biosynthesis.

A highly sensitive and specific method has been developed for determination of the level of 7 alpha-hydroxy-4-cholesten-3-one in plasma. This method is based on a stable isotope-dilution technique by gas chromatography-selected-ion monitoring mass spectrometry. 7 alpha-Hydroxy-4-cholesten-3-one was extracted from plasma by saltingout extraction, and then purified by serial solid-phase extractions. The extract was treated with O-methylhydroxyl-amine hydrochloride and then dimethylethylsilylated. The resulting methyloxime-dimethylethylsilyl ether derivative was quantified by gas chromatography-selected-ion monitoring mass spectrometry with a high-resolution mode. The plasma levels of 7 alpha-hydroxy-4-cholesten-3-one were correlated with the cholesterol 7 alpha-hydroxylase activity to a higher degree than those of any other form of 7 alpha-hydroxycholesterol (r = 0.84, n = 16, p < 0.0001). The present method was applied to monitor the circadian rhythm of 7 alpha-hydroxy-4-cholesten-3-one levels in human plasma. It was concluded that the plasma level of 7 alpha-hydroxy-4-cholesten-3-one is a useful index for the monitoring of bile acid biosynthesis in the human liver.

Adult↗
PubMed1994

Multiple tyrosine protein kinases in rat hippocampal neurons: isolation of Ptk-3, a receptor expressed in proliferative zones of the developing brain.

Tyrosine protein kinases are likely to play an important role in the maintenance and/or development of the nervous system. In this study we have used the PCR cloning technique to isolate sequences derived from tyrosine kinase genes expressed in cultured hippocampal neurons obtained from 17.5-day-old rat embryos. Nucleotide sequence analysis of 209 independent clones revealed sequences derived from 25 tyrosine kinases, of which two corresponded to previously unreported genes. One of the PCR clones, ptk-2, belongs to the Jak family of cytoplasmic tyrosine kinases. The second clone, ptk-3, was derived from a gene encoding an additional class of tyrosine kinase receptors whose extracellular domains contain regions of homology with coagulation factors V and VIII and complement component C1. Transcripts encoding the Ptk-3 receptor are present in a variety of embryonic and adult tissues with highest levels observed in brain. During development, ptk-3 transcripts are most abundant in the proliferative neuroepithelial cells of the ventricular zone, raising the possibility that this receptor may play an important role in the generation of the mammalian nervous system.

Amino Acid Sequence↗
PubMed1994

Induction of interferon-gamma, interleukin-4, and transforming growth factor-beta in rats orally tolerized against experimental autoimmune myasthenia gravis.

Oral administration of nicotinic acetylcholine receptor (AChR) to Lewis rats prior to myasthenogenic immunization with Torpedo AChR+complete Freund's adjuvant (CFA) results in the prevention of experimental autoimmune myasthenia gravis (EAMG) and the suppression of AChR-specific B cell responses and counteracts the development of AChR-reactive interferon-gamma (IFN-gamma) secreting T cells. To study the involvement of the T helper type 1 (Th1) cell-related lymphokine IFN-gamma, the Th2 cell-related interleukin-4 (IL-4), and transforming growth factor beta (TGF-beta) that suppresses the synthesis of IFN-gamma and IL-4, we used in situ hybridization with complementary DNA oligonucleotide probes to enumerate mononuclear cells (MNC) expressing mRNA for the cytokines IFN-gamma, IL-4, and TGF-beta. Upon in vivo recognition of AChR, popliteal, inguinal, and mesenteric lymph nodes, spleen and thymus of rats with EAMG contained higher levels of IFN-gamma, IL-4, and TGF-beta mRNA-expressing cells compared to CFA-injected control rats, implicating the involvement in EAMG of AChR-reactive Th1 and Th2 cells in parallel. TGF-beta was also upregulated in EAMG. Oral tolerance to EAMG was characterized by suppression of the levels of MNC expressing IFN-gamma and IL-4, but augmentation of cells expressing TGF-beta. The results suggest that IFN-gamma, IL-4, and TGF-beta are involved in the development of EAMG, and that TGF-beta is important in the induction of oral tolerance to EAMG.

Animals↗
PubMed1994

Low protein diets increase neuropeptide Y gene expression in the basomedial hypothalamus of rats.

Food deprivation elevates both neuropeptide Y (NPY) gene expression in the basomedial hypothalamus and NPY levels in the paraventricular nucleus (PVN). To gain a better understanding of the dietary control of NPY, we systematically examined the effects of macronutrient restriction on the gene expression of NPY in the basomedial hypothalamus and NPY content in the PVN. Rats were fed one of eight different diets for 12 d. The control group was fed a modified AIN-76 diet. One group was fed the modified AIN-76 diet but was restricted in energy by 50%. Six isocaloric (to the control diet) test diets were prepared, each with an individual macronutrient reduced by 50%. Neuropeptide Y gene expression was elevated in protein-restricted animals as well as in energy-restricted animals. Carbohydrate or fat restriction seemed to have no effect on NPY gene expression. Though the NPY content in the PVN was not different between any groups, two findings were consistent with greater NPY release in protein-restricted animals. Animals fed a low protein diet were hyperphagic and had a greater amount of body fat. This study suggests that low levels of dietary protein may have a role in the regulation of NPY gene expression.

Animals↗
PubMed1994

Interaction of calmodulin with synthetic deletion peptides of melittin.

The 26-residue peptide melittin present in bee venom has been shown to bind calmodulin tightly. In this study we synthesized the following series of deletion peptides of melittin by the solid-phase method: Mel12, Mel13, Mel14, Mel15, Mel15F. The results of this study show that the deletion peptides Mel14 and Mel15 have almost the same binding activity as the intact native peptide. Each deletion peptide forms a 1:1 complex with calmodulin according to electrophoresis analysis. When the tryptophanyl residue of Mel15 was replaced by the phenylalaninyl residue, the dissociation constant of the peptide-calmodulin complex increased. This shows the importance of the tryptophanyl residue for binding to calmodulin.

Amino Acid Sequence↗
PubMed1994

Regulation of Escherichia coli purA by purine repressor, one component of a dual control mechanism.

Escherichia coli purA encodes adenylosuccinate synthetase, one of two enzymes required for synthesis of AMP from IMP. purA is subject to two- to threefold regulation by purR and about twofold regulation by a purR-independent mechanism. The 5'-flanking region of purA confers purR-dependent transcriptional regulation of purA but not the purR-independent regulation. Two operator sites in the 5'-flanking region which bind purine repressor in vitro and are required for in vivo regulation were identified. The purR-independent regulation may be posttranscriptional. It is now established that all transcription units involved in de novo synthesis of purine nucleotides, nine pur operons, as well as purR itself and guaBA, are subject to purR control.

Adenosine Monophosphate↗
PubMed1994

[The effect of IL-1 receptor antagonist on bleomycin-induced pulmonary fibrosis].

Interleukin-1 (IL-1) is a cytokine with diverse biological activities. It can serve as a fibroblast (FB) growth factor which involves in the development of pulmonary fibrosis. IL-1 receptor antagonist (IL-1ra) can compete with IL-1 for occupancy of surface receptors of target cells without agonist effect. In order to find a new method to treat pulmonary fibrosis, we investigated the effect of recombinant human IL-1ra on the development of pulmonary fibrosis by evaluating collagen content, histological change, and TGF-beta mRNA expression in the rats bleomycin-induced pulmonary fibrosis. The results indicate are that there are no significant difference between the IL-1ra treated group and the control group.

Animals↗
PubMed1994

[Repair of heel defect with a free medial plantar flap].

The results of reconstruction of plantar heel defects with a local random flap or an island medial plantar flap have in a majority of cases been satisfactory. However, in cases of extensive plantar defects, local tissue transfers are almost impossible. Since 1988, 8 cases with extensive plantar defects have been treated using free medial plantar cutaneous or musculocutaneous flaps. All flaps survived. Six weeks postoperatively, full weight-bearing was obtained and normal activities were resumed. No ulceration in the flaps has been noted in the follow up period between 6 and 24 months, and the two point discrimination was from 20 to 24 mm. The paper particularly points out the importance of nerve repair in the reconstruction, because recovery of the protective sensation is the most important factor to prevent plantar ulceration, and is the basis for good operative results.

Adolescent↗
PubMed1994

[Cytosol estrogen and progesterone receptors in female genital system malignant tumors].

Specimens from 344 cases of endometrial carcinoma, 289 cases of ovarian carcinoma, 177 cases of cervical carcinoma, 10 vulva and 4 fallopian tube carcinoma were assayed for cytosol estrogen and progesterone receptor (ER, PR) contents with dextran-coated charcoal (DCC) method. Positive rates of ER and PR in these malignant tumors in relation to menstrual cycle, histological differentiation, clinical stage and prognosis of disease were studied. The results suggested that the contents of ER and PR may play a role in building endocrine therapy and prognosis in the postoperative period. Further study on vulvar and fallopian tube carcinomas should be undertaken.

Adenocarcinoma↗
PubMed1994

[Body surface dynamic monitoring of respiratory muscles in patients with cor pulmonale].

Electromyography (EMG) of diaphragm (Edi) and intercostal muscle (Ein) in 30 healthy volunteers and 28 patients with cor pulmonale or pulmonary fibrosis were analysed. The results show that (1) there is no obvious activity of Ein to be observed and the frequency spectra are stable when the healthy volunteers breath quietly, (2) the activity of Ein and the amplitude of Edi increase when patients are in compensation stage, (3) the patients with serious respiratory failure, the amplitude of Edi decreases remarkably, (4) the frequency spectras of Edi appear wave-like changes with the breathing pattern of patients.

Adult↗
PubMed1993

Simultaneous determination of mevalonate and 7 alpha-hydroxycholesterol in human plasma by gas chromatography-mass spectrometry as indices of cholesterol and bile acid biosynthesis.

A very sensitive and specific method for the simultaneous determination of mevalonate and 7 alpha-hydroxycholesterol in human plasma is described. The assay is based on isotope dilution mass spectrometry: the extracts from plasma were treated with benzylamine followed by dimethylethylsilylimidazole, then the resulting dimethylethylsilyl ether derivatives of mevalonylbenzylamide and 7 alpha-hydroxycholesterol were determined by gas chromatography-mass spectrometry using high-resolution selected-ion monitoring. Simple regression analysis revealed significant correlations between the plasma level of mevalonate and the hepatic activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (EC 1.1.1.34) (r = 0.83, P < 0.01) and between the plasma level of free 7 alpha-hydroxycholesterol and the hepatic activity of cholesterol 7 alpha-hydroxylase (EC 1.14.13.7) (r = 0.76, P < 0.05).

Adult↗
PubMed1993

Hepatic cholesterol and bile acid synthesis in Japanese patients with cholesterol gallstones.

In Japan the composition of gallstones is changing rapidly from the once-predominant brown-pigment stones to cholesterol ones. The present work was undertaken to clarify the mechanism of cholesterol supersaturated bile production in Japanese patients with cholesterol gallstones. In 26 non-obese and normolipidemic patients (11 with cholesterol gallstones, 8 with black- or brown-pigment gallstones, 7 without gallstones) a liver biopsy and hepatic bile were surgically obtained under standardized conditions. The cholesterol saturation of hepatic bile was significantly higher in cholesterol gallstone patients than in gallstone-free controls (195 +/- 10 vs. 146 +/- 8%, respectively; P < 0.01). The microsomal activities of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme for cholesterol synthesis, cholesterol 7 alpha-hydroxylase, the rate-limiting enzyme for bile acid synthesis, and 7 alpha-hydroxy-4-cholesten-3-one 12 alpha-hydroxylase (12 alpha-hydroxylase), the rate-limiting enzyme for cholic acid synthesis, were assayed simultaneously in the same subjects. There were positive correlations between HMG-CoA reductase and cholesterol 7 alpha-hydroxylase activities (Rs = 0.62, P < 0.005), and between cholesterol 7 alpha-hydroxylase and 12 alpha-hydroxylase activities (Rs = 0.44, P < 0.05) in all subjects, irrespective of the existence of gallstones. The activities of the three rate-limiting enzymes did not differ significantly among the three groups (cholesterol stone, pigment stone and stone-free). In conclusion, the cholesterol supersaturation of hepatic bile in nonobese and normolipidemic Japanese patients with cholesterol gallstones does not result from an increased hepatic cholesterol synthesis or a decreased bile acid synthesis.

Bile Acids and Salts↗
PubMed1993

Entropic analysis of biological growth models.

Using the concept of isomorphism, we provide a quantitative description of the thermodynamic characteristics of the Logistic, Bertalanffy, and Gompertz biological growth models. With the help of the entropy expressions derived from the isomorphic probabilistic models, we show that the Logistic, Bertalanffy, and Gompertz growth models have distinct thermodynamic characteristics, though they have similar sigmoid trajectories in the time domain. The entropic analysis further reveals that the Gompertz model corresponds to a completely open system, in which cells receive adequate nutrition and competition among cells can be neglected. We have also applied the present entropic analysis to the modeling of tumor growth. Our results suggest that the entropic expression provides a theoretical justification for using the Gompertz model for describing the development of tumor cell populations. The entropic analysis may play an important role in studying the mechanisms of different biological growth processes.

Animals↗