Search PubMed⌕ Search

Biomedical subjects

L He

Publications and source records attributed to L He.

At least 325 records · Page 18Linked to original sources
PubMed1996

Structural comparison of a portion of the rat and mouse growth hormone receptor/binding protein genes.

A portion of the rat growth hormone receptor (GHR) gene was cloned by PCR. Restriction enzyme digestion and DNA sequence analyses revealed that an exon, exon 8A, encoding the carboxy terminus of the rat serum growth hormone binding protein (GHBP) was located between exons 7 and 8 of the rat GHR gene. Two tandem poly-adenylation (poly A) signals for the GHBP mRNA were found in the 3'-untranslated region of this exon. In addition, a GT repeat tract was found adjacent to the 5'-splice donor site of intron 7/8A. The similarity of the nucleotide sequences of the rat and mouse GHR/GP gene suggests that the poly A signals and GT repeat may be involved in the regulation of GHR and GHBP expression.

Animals↗
PubMed1996

Laminin and heparan sulfate proteoglycan mediate epithelial cell polarization in organotypic cultures of embryonic lung cells: evidence implicating involvement of the inner globular region of laminin beta 1 chain and the heparan sulfate groups of heparan sulfate proteoglycan.

The extracellular matrix and in particular the basement membrane (BM) play an important role in the induction of organotypic rearrangement of cells in culture. This process involves cell aggregation, sorting into epithelial and mesenchymal components, epithelial cell polarization, and lumen formation. In this study, a combination of laminin (LM) and heparan sulfate proteoglycan (HSPG), two major BM constituents, induced organotypic rearrangement of embryonic mouse lung cells. In the absence of LM/HSPG supplementation, the cells sorted into epithelial and mesenchymal compartments but epithelial cell polarization and lumen formation did not occur. Neither LM nor HSPG alone could trigger this process. Synthetic peptide F-9, representing an amino acid sequence from the inner globular region of the laminin beta1 chain (RYVVLPRPVCFEKGMNYTVR) induced organotypic cell rearrangement when substituted for LM. Exogenous LM as well as peptide F-9 were localized at the epithelial-mesenchymal interface of organotypic cultures, where a BM-like structure is formed de novo. Organotypic cell rearrangement was blocked by heparin, heparan sulfate, or antibodies against peptide F-9. Binding assays indicated that peptide F-9 interacts with HSPG but not with LM or type IV collagen. Preincubation of embryonic lung cells with peptide F-9 resulted in a significant increase in cell attachment to HSPG but not to other major BM constituents. These findings suggest that the interaction between LM and BM HSPG is critical for the development of epithelial cell polarization and lumen formation. This interaction occurs at the epithelial-mesenchymal interface and is mediated by a site in the LM molecule represented by peptide F-9 and the heparan sulfate groups of HSPG.

Amino Acid Sequence↗
PubMed1996

Distinguishing antemortem from postmortem injuries by LTB4 quantification.

Leukotriene B4 (LTB4) in skin samples from seven forensic cases was detected by HPLC to distinguish their antemortem or postmortem origin. In total, there were thirteen antemortem and seven postmortem specimens. The results showed that LTB4 was found in all antemortem wound specimens which were either fresh, or refrigerated or fixed in formalin for less than 10 days. In contrast, LTB4 could not be detected in postmortem wound specimens. These results suggested that detecting the content of LTB4 is a useful method for distinguishing antemortem from postmortem injuries.

Adult↗
PubMed1996

Insulin action on glucose transport and plasma membrane GLUT4 content in skeletal muscle from patients with NIDDM.

We investigated the response of the glucose transport system to insulin, in the presence of ambient glucose concentrations, in isolated skeletal muscle from seven patients with non-insulin-dependent diabetes mellitus (NIDDM) (age, 55 +/- 3 years, BMI 27.4 +/- 1.8 kg/m2) and seven healthy control subjects (age, 54 +/- 3 years, BMI 26.5 +/- 1.1 kg/m2). Insulin-mediated whole body glucose utilization was similar between the groups when studied in the presence of ambient glucose concentrations (approximately 10 mmol/l for the NIDDM patients and 5 mmol/l for the control subjects). Samples were obtained from the vastus lateralis muscle, by means of an open muscle biopsy procedure, before and after a 40-min insulin infusion. An increase in serum insulin levels from 54 +/- 12 to 588 +/- 42 pmol/l, induced a 1.6 +/- 0.2-fold increase in glucose transporter protein (GLUT4) in skeletal muscle plasma membranes obtained from the control subjects (p < 0.05), whereas no significant increase was noted in plasma membrane fractions prepared from NIDDM muscles, despite a similar increase in serum insulin levels. At concentrations of 5 mmol/l 3-O-methylglucose in vitro, insulin (600 pmol/l) induced a 2.2-fold (p < 0.05) increase in glucose transport in NIDDM muscles and a 3.4-fold (p < 0.001) increase in the control muscles. Insulin-stimulated 3-O-methylglucose transport was positively correlated with whole body insulin-mediated glucose uptake in all participants (r = 0.78, p < 0.001) and negatively correlated with fasting plasma glucose levels in the NIDDM subjects (r = 0.93, p < 0.001). Muscle fibre type distribution and capillarization were similar between the groups. Our results suggest that insulin-stimulated glucose transport in skeletal muscle from patients with NIDDM is down-regulated in the presence of hyperglycaemia. The increased flux of glucose as a consequence of hyperglycaemia may result in resistance to any further insulin-induced gain of GLUT4 at the level of the plasma membrane.

3-O-Methylglucose↗
PubMed1996

A locus for bipolar affective disorder on chromosome 4p.

The main clinical feature of bipolar affective disorder is a change of mood to depression or elation. Unipolar disorder, also termed major depressive disorder, describes the occurrence of depression alone without episodes of elevated mood. Little is understood about the underlying causes of these common and severe illnesses which have estimated lifetime prevalences in the region of 0.8% for bipolar and 6% for unipolar disorder. Strong support for a genetic aetiology is found in the familial nature of the condition, the increased concordance of monozygotic over dizygotic twins and adoption studies showing increased rates of illness in children of affected parents. However, linkage studies have met with mixed success. An initial report of linkage on the short arm of chromosome 11 (ref. 4) was revised and remains unreplicated. Reports proposing cosegregation of genes found on the X chromosome with bipolar illness have not been supported by others. More recently bipolar disorder has been reported to be linked with markers on chromosomes 18, 21, 16 and a region on the X chromosome different from those previously suggested. We have carried out a linkage study in twelve bipolar families. In a single family a genome search employing 193 markers indicated linkage on chromosome 4p where the marker D4S394 generated a two-point lod score of 4.1 under a dominant model of inheritance. Three point analyses with neighbouring markers gave a maximum lod score of 4.8. Eleven other bipolar families were typed using D4S394 and in all families combined there was evidence of linkage with heterogeneity with a maximum two-point lod score of 4.1 (theta = 0, alpha = 0.35).

Bipolar Disorder↗
PubMed1996

Syntaxin 4 in 3T3-L1 adipocytes: regulation by insulin and participation in insulin-dependent glucose transport.

Syntaxins are thought to be membrane receptors that bind proteins of the synaptobrevin/vesicle-associated membrane protein (VAMP) family found on transport vesicles. Recently, we detected synaptobrevin II and cellubrevin on immunopurified vesicles containing the glucose transporter 4 (GLUT4) in insulin-responsive cells. In an effort to identify the plasma membrane receptors for these vesicles, we now examine the expression of syntaxins in the 3T3-L1 adipocyte cell line. Neither syntaxin 1A nor 1B was found, in keeping with the neuronal restriction of these isoforms. In contrast, syntaxins 2 and 4 were readily detectable. By subcellular fractionation and estimation of protein yields, 67% of syntaxin 4 was localized to the plasma membrane, 24% to the low-density microsomes, and 9% to the high-density microsomes. Interestingly, acute insulin treatment decreased the content of syntaxin 4 in low-density microsomes and caused a corresponding gain in the plasma membrane fraction, reminiscent of the recruitment of GLUT4 glucose transporters. In contrast, there was no change in the distribution of syntaxin 2, which was mostly associated in the plasma membrane. A fraction of the intracellular syntaxin 4 was recovered with immunopurified GLUT4-containing vesicles. Moreover, anti-syntaxin 4 antibodies introduced in permeabilized 3T3-L1 adipocytes significantly reduced the insulin-dependent stimulation of glucose transport, in contrast to the introduction of irrelevant immunoglobulin G, which was without consequence. We propose that either the plasma membrane and/or the vesicular syntaxin 4 are involved in docking and/or fusion of GLUT4 vesicles at the cell surface of 3T3-L1 adipocytes.

3T3 Cells↗
PubMed1996

A genome-wide search for linkage in a large bipolar family: comparison of genotyping accuracy using di- and tetranucleotide repeat microsatellite markers.

Linkage of bipolar disease to several markers mapping to chromosome 4p has been reported in an extended family multiply affected with bipolar affective disorder and no linkage was found at other locations with 106 microsatellite markers, of which 58 were dinucleotide and 48 tetranucleotide repeats [Blackwood et al. (1996), Nature Genetics, 12, 427-430]. Collecting these data provided the opportunity to assess the usefulness and accuracy of the automated linkage preprocessor (ALP) programme in a linkage study and to make a detailed comparison of di- and tetranucleotides with this semi-automated system. Genotypes were acquired using the automated linkage preprocessor (ALP) without any manual intervention at any stage of the procedure and results of analyses of these data were compared with results based on genotypes checked by visual inspection of the data. The ALP program was found to be timesaving and reliable and yielded similar results to non-automated reading using both di- and tetranucleotide repeat microsatellite markers. Tetranucleotides had fewer errors due to multiple genotypes and a lower incidence of stutter peaks making them more informative than dinucleotides in this linkage study.

Bipolar Disorder↗
PubMed1996

Recombination patterns around the breakpoints of a balanced 1;11 autosomal translocation associated with major mental illness.

The frequency and extent of pairing failure around human translocations are unknown. We have examined the pattern of recombination around the breakpoints of a balanced autosomal translocation t(1;11) (q43;q21) associated with major mental illness. DNA was available from 17 carriers and 10 non-translocation carriers with meioses involving four generations. The derivative 1 and 11 chromosomes were also isolated in somatic cell hybrids and used to confirm phase. We have genotyped pedigree members using 20 polymorphic markers within 10 cM on either side of both chromosome 1 and 11 breakpoints. We find no significant reduction of recombination in the vicinity of either breakpoint. However we estimate that there are insufficient meioses even in this large family to make a meaningful interpretation and suggest that sperm typing alone can answer these interesting questions.

Chromosome Mapping↗
PubMed1996

Iron is required to relieve inhibitory effects on NifL on transcriptional activation by NifA in Klebsiella pneumoniae.

In Klebsiella pneumoniae, products of the nitrogen fixation nifLA operon regulate transcription of the other nif operons. NifA activates transcription by sigma54-holoenzyme. In vivo, NifL antagonizes the action of NifA under aerobic conditions or in the presence of combined nitrogen. In contrast to a previous report, we show that depletion of iron (Fe) from the growth medium with the chelating agent o-phenanthroline (20 microM) mimics aerobiosis or combined nitrogen in giving rise to inhibition of NifA activity even under anaerobic, nitrogen-limiting conditions. Adding back Fe in only twofold molar excess over phenanthroline restores NifA activity, whereas adding other metals fails to do so. By using strains that lack NifL, we showed that NifA activity itself does not require Fe and is not directly affected by phenanthroline. Hence, Fe is required to relieve the inhibition of NifA activity by NifL in vivo. Despite the Fe requirement in vivo, we have found no evidence that NifL contains Fe or an iron-sulfur (Fe-S) cluster. Determination of the molecular mass of an inhibitory form of NifL overproduced under aerobic conditions indicated that it was not posttranslationally modified. When NifL was synthesized in vitro, it inhibited transcriptional activation by NifA even when it was synthesized under anaerobic conditions in the presence of a high Fe concentration or of superoxide dismutase, which is known to protect some Fe-S clusters. Moreover, overproduction of superoxide dismutase in vivo did not relieve NifL, inhibition under aerobic conditions, and attempts to relieve NifL inhibition in vitro by reconstituting Fe-S clusters with the NifS enzyme (Azotobacter vinelandii) were unsuccessful. Since we obtained no evidence that Fe acts directly on NifL or NifA, we postulate that an additional Fe-containing protein, not yet identified, may be required to relieve NifL inhibition under anaerobic, nitrogen-limiting conditions.

Aerobiosis↗
PubMed1996

Dynamic changes of constituents in bronchoalveolar lavage fluid in experimental silicotic rats.

Bronchoalveolar lavage (BAL) is a useful and safe method for sampling cellular and biochemical components from the lung. Analysis of bronchoaveolar lavage fluid (BALF) constituents is useful for defining the stage of disease, and for assessing disease progression and the response to therapy in lung disorders. We studied the dynamic changes in various indices for BALF and the accompanying silicotic changes in the lungs of rats at different times after quartz instillation. Total cell counts, LDH activity, protein concentration, and lipoperoxide (LPO) in the BALF of experimental silicotic rats were significantly higher than those of control rats (P < 0.05 or 0.01). After instillation, quartz content, total cell counts, LDH activity and protein concentration in BALF tended to decrease over time. These findings suggested that in acute silicosis, quartz can induce serious inflammation and damage the lung, with acute lung proteinosis seen as the main change in this stage.

Animals↗
PubMed1996

[Transplantation of human primary in-situ and invasive breast carcinoma in nude mice].

In order to establish nude mice model of early and advanced breast cancers, 15 in-situ breast carcinomas and 31 invasive breast carcinomoas were transplanted in 155 nude mice subcutaneously. A slow-release pellet of 17-beta estradiol was also implanted subcutaneously. During ten months of observation, the in-situ breast cancer tissue eventually did not grow. Light microscopy showed that the implants kept the structure of in-situ carcinoma without invasion. Of 31 invasive carcinomas, only one diagnosed pathologically as multifocal dedifferentiated ductal carcinoma grew well and was serially passaged. It was estrogen- and progesterone-receptor negative, p53 protein negative and c-erbB-2 protein positive. Its DNA ploidy was near tetraploidy.

Adult↗
PubMed1996

[Lipopolysaccharide (LPS) induced pulmonary inflammatory response and effects of TNF in immunocompromised host (ICH)].

OBJECTIVE: To investigate the pulmonary inflammatory response and TNF-mediated effects in ICH. METHODS: ICH models of guinea pigs were induced successfully by receiving daily intraperitoneal injections of cyclophosphamide (15mg.kg-1.d-1) plus daily subcutaneous injection of cortisone acetate (100mg.kg-1.d-1) for a total of 7 consecutive days. On the day after the final dose of drugs, guinea pigs were challenged intratracheally with LPS (200 micrograms/animal) and were lavaged before and 1, 3, 5, 8, 24 hours after challenged, respectively. RESULTS: Five hours after LPS challenged, total counts of bronchoalveolar fluid (BALF) cells and the proportion of PMN increased significantly. Although the counts of both PAM and PMN increased, the proportion of PAM decreased gradually accompanied by increase of the proportion of PMNs. Hematoxylin eosin stained lung sections after challenged with LPS showed an acute intraalveolar inflammatory response. After intra-tracheal injection of LPS, the TNF level in BALF progressively increased. Both the TNF level and PMN count started to increase at 1 hour after LPS challenge, peaked at 5 hours. The TNF level in serum did not increase markedly after intratracheal injection of LPS. In the development of an inflammatory response, a large amount of TNF were released in BALF, the level of TNF in BALF was closely matched the influx of PMN. CONCLUSIONS: The data suggested that TNF was one of the cytokines which mediated influx of PMNs and inflammation. High level of TNF released in BALF of ICH could induce the lung injury. The systemic inflammatory response of ICH was involving immunosuppressed state after intratracheal injection of LPS, however, strong intraalveolar inflammatory response still occurred, which reflected the phenomenon of "compartmentalization" in inflammatory response.

Animals↗
PubMed1996

[Chemical constituents of Aster albscens Hand.-Mazz].

Four compounds, stigmasterol, D-hurulon-14-en-3-ol, stigma-delta7.22-dien-3beta-palmitate and friedelin were isolated from the root of Aster albscens for the first time. Their structures were elucidated by spectral methods.

Asteraceae↗
PubMed1995

A contiguous clone map over 3 Mb on the long arm of chromosome 11 across a balanced translocation associated with schizophrenia.

Forty-nine clones derived by microdissection of a schizophrenia-associated t(1;11)(q42.1;q14.3) breakpoint region have been assigned by somatic cell hybrid mapping to seven discrete intervals on the long arm of human chromosome 11. Eleven of the clones were shown to map to a small region immediately distal to the translocation breakpoint on 11q. A 3-Mb contiguous clone map of this region was established by isolation of corresponding YAC recombinants. The contig was oriented and shown to traverse the translocation breakpoint by FISH and microsatellite marker analysis. This contig will facilitate the isolation of candidate sequences whose expression may be affected by the translocation.

Base Sequence↗