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Biomedical subjects

L He

Publications and source records attributed to L He.

At least 379 records · Page 21Linked to original sources
PubMed1994

An exon encoding the mouse growth hormone binding protein (mGHBP) carboxy terminus is located between exon 7 and 8 of the mouse growth hormone receptor gene.

A C57 black/6 mouse genomic library was screened for mGHR/BP using a mGHR cDNA hybridization probe. Two clones (mGHR-GA and mGHR-GB) were isolated. mGHR-GA contained an insert of 16 kb and hybridized only to exon 4 whereas mGHR-GB possessed an insert of 20 kb and hybridized to exons 6-10 of the mGHR cDNA. Oligonucleotide sequencing analysis confirmed that the mGHR-GA contained exon 4 and that the mGHR-GB possessed mGHR/BP genomic sequences from intron V through the 3' region of mGHR. In addition, mGHR-GB also contained a region, designated exon 8A, encoding the carboxy terminus of mGHBP. This exon is located between exons 7 and 8 of mGHR/BP gene. Two poly(A) additional signal sequences were found 54 bp downstream of the stop codon of mGHBP. Additionally, introns between exons 3/4 and 4/5 are > 12 and > 3 kb, respectively. Also, introns between exons 5/6, 6/7, 7/8A, 8A/8 (3' region of mGHBP), 8/9, 9/10, and the 3' region of mGHR are approx > 3 kb, 4 kb, 287 bp, 1569 bp, 6 kb, 265 bp, and > 3 kb, respectively. This study supports the hypothesis that mGHBP is generated by alternative splicing of a common primary mGHR transcript. It also demonstrates differences and similarities between mGHR/BP and hGHR genes.

Animals↗
PubMed1994

Beneficial effect of an ACTH-(4-9) analog (Org2766) in the treatment of experimental cortex lesion in rats.

This paper reports that lesions of the medial frontal cortex (MFC) caused behavioral deficit in rats and that this deficit could be attenuated by a well formulated treatment with Org2766, an analog of ACTH-(4-9). Wistar rats were distributed in 3 groups: MFC lesion treated with saline (M-N); MFC lesion treated with Org2766 (M-O); and sham-operation treated with saline (S). Repeated Org2766 or saline injection commenced from the day of surgery and lasted for 13 days. After surgery, the rats were trained in a passive avoidance task and then in an active avoidance task. MFC lesions were found to be strongly associated with behavioral deficits. The M-N group rats displayed poor retention of the passive avoidance response and showed much slower learning of the active avoidance task as compared to S group rats. The result showed that chronic Org2766 administration improved the behavioral performance of both tasks in MFC lesioned rats. The also revealed that the superoxide dismutase (SOD) activity was significantly increased in the M-O group as compared to the M-N group 15 days after surgery. The possible mechanisms related to the beneficial effect of Org2766 on cortex damage are discussed.

Adrenocorticotropic Hormone↗
PubMed1993

High-performance liquid chromatographic separation of ondansetron enantiomers in serum using a cellulose-derivatized stationary phase and solid-phase extraction.

R(-)-Ondansetron and S(+)-ondansetron in human serum were resolved and quantified using a stereospecific HPLC method. Each enantiomer and the internal standard prazosin were isolated from serum using a solid-phase extraction procedure on a cyanopropyl column. Recoveries of 97, 96 and 88% were obtained for the R(-)-enantiomer, the S(+)-enantiomer, and the internal standard, respectively. A cellulose-based chiral analytical column (Chiralcel OD) was used with a mobile phase consisting of hexane-95% ethanol-2-propanol-acetonitrile (65:25:10:1, v/v). Linear calibration curves were obtained for each enantiomer in serum in the concentration range 10-200 ng/ml. The limit of quantitation of each enantiomer was 10 ng/ml. The detection limit for each enantiomer in serum using UV detection at 216 nm was 2.5 ng/ml (signal-to-noise ratio of 3).

Cellulose↗
PubMed1993

Lignification in cell suspension cultures of Pinus taeda. In situ characterization of a gymnosperm lignin.

Pinus taeda suspension cultures grown in medium containing 2,4-dichlorophenoxyacetic acid showed only primary cell wall formation and essentially no lignification, as determined by histochemical, ultrastructural, chemical, and NMR spectroscopic analyses. However, these cultures maintained a functional phenylpropanoid pathway as demonstrated by formation of the lignans (-)-matairesinol and (-)-pinoresinol. Administration of [1-13C]Phe to these cultures, followed by solid-state carbon-13 NMR spectral analysis of their cell walls, demonstrated that the phenylalanine incorporated into the cell wall matrix was primarily as protein, rather than lignin. Successive transfer of the 2,4-dichlorophenoxyacetic acid-grown cultures to alpha-naphthaleneacetic acid-containing medium induced cell wall thickening concomitant with lignification. The presence of lignin was confirmed by histochemical, ultrastructural, chemical, biochemical, and NMR spectroscopic analyses. Specific labeling of the lignin polymer in situ with [1-13C]-, [2-13C]-, and [3-13C]Phe and analysis of the cell wall preparations by solid-state carbon-13 NMR spectroscopy permitted the first direct determination of the in situ bonding patterns in a gymnosperm lignin. Several dominant interunit linkages were observed, including beta-O-aryl, furanofuran, phenylcoumarin, and phenolic-linked monolignols, consistent with those predicted but hitherto not proven. Finally, milled wood lignin derivatives prepared from these 13C-specifically enriched lignin tissues gave a relatively high fidelity copy of the native lignin.

Cell Wall↗
PubMed1993

Highly sensitive object location in tissue models with linear in-phase and anti-phase multi-element optical arrays in one and two dimensions.

Based upon previous observations of low-frequency photon diffusion waves within highly scattering tissue, this paper explores the "near-field" phenomena of such waves of approximately 10-cm wavelength with 200-MHz phase modulation equipment. Multiple-element source arrays consist of laser diode sources modulated at 180 degrees out of phase with respect to the other sources. The diffusing waves originating from the out-of-phase sources give, in the midplane, an amplitude null and a sharp phase transition. These may be observed in a highly scattering intralipid medium simulating the breast or brain (0.5% intralipid), 3-5 cm from the transmitting laser diodes. In the plane containing the array, there is a high sensitivity for a small volume of a hidden absorber (indocyanine green) deep within a highly scattering medium; 20 pmol in a volume of 70 microliters can be detected. Two-dimensional arrays consisting of four or more elements in two orthogonal planes give sensitivity on both axes similar to the one-dimensional array. Measurements show that in the presence of a light-absorbing object, the amplitude null and the interference plane becomes a curved surface which is deflected toward the heterogeneity. The degree of deflection is related to the volume and the absorption characteristics of the heterogeneity and provides detection of the heterogeneity, and thereby may provide localization information for the detection of small tumors within the human breast, or stroke volumes, aneurysms, and tumors in the human brain.

Brain↗
PubMed1993

Transformation-sensitive cells in G2/M-phase are not promoted by TPA following 137Cs gamma-rays.

Mouse C3H 10T1/2 cells are most sensitive to radiation-induced neoplastic transformation in the G2/M-phase of the cell cycle. When synchronized 10T1/2 cells were exposed to phorbol 12-myristate 13-acetate (TPA) after irradiation, transformation of cells not in the transformation-sensitive window was enhanced, but transformation of cells already in the transformation-sensitive window was not. Earlier work showed that (a) TPA enhances the frequency of transformation of both high and low dose-rate gamma-irradiated cells by about the same factor, but that (b) TPA enhances the transformation of cells exposed to low dose-rate fission spectrum neutrons appreciably less than cells exposed to high dose-rate fission spectrum neutrons. The latter observation is consistent with the inability of TPA to promote cells in the transformation-sensitive window and with the role of such cells in enhancing transformation by protracted doses of neutrons. The data provide a cellular basis for studying the biochemical/molecular aspects of TPA promotion in vitro.

Animals↗
PubMed1993

Aberrations of p53 gene in human hepatocellular carcinoma from China.

Allele losses and mutations have been examined in 38 cases of primary hepatocellular carcinomas (HCC) from different geographic areas of China by Southern, single-strand conformational polymorphism (SSCP) and direct DNA sequencing analyses. Two of 12 samples from Qi-Dong and six of 18 HCCs from Shanghai showed loss of heterozygosity (LOH) at the loci on chromosome 17p13.3. All of the nine mutations in the p53 gene detected in HCC from Qi-Dong were clustered at the third base of codon 249, i.e. G:C to T:A, leading to an arginine to serine change. In contrast, 18 HCC samples from Shanghai contained three mutations at codons 249, 255 and 279. These results suggested a relationship between the spectrum of p53 aberration and environmental risk factors in these two geographic areas. Since no correlation between the state of HBV DNA and p53 aberration was observed, other factors such as dietary exposure to aflatoxin B1 (AFB1) might be responsible for the mutational hotspot at codon 249 in HCCs from Qi-Dong area.

Aflatoxin B1↗
PubMed1993

Loss of function of Saccharomyces cerevisiae kinesin-related CIN8 and KIP1 is suppressed by KAR3 motor domain mutations.

The kinesin-related products of the CIN8 and KIP1 genes of Saccharomyces cerevisiae redundantly perform an essential function in mitosis. The action of either gene-product is required for an outwardly directed force that acts upon the spindle poles. We have selected mutations that suppress the temperature-sensitivity of a cin8-temperature-sensitive kip1-delta strain. The extragenic suppressors analyzed were all found to be alleles of the KAR3 gene. KAR3 encodes a distinct kinesin-related protein whose action antagonizes Cin8p/Kip1p function. All seven alleles analyzed were altered within the region of KAR3 that encodes the putative force-generating (or "motor") domain. These mutations also suppressed the inviability associated with the cin8-delta kip1-delta genotype, a property not shared by a deletion of KAR3. Other properties of the suppressing alleles revealed that they were not null for function. Six of the seven were unaffected for the essential karyogamy and meiosis properties of KAR3 and the seventh was dominant for the suppressing trait. Our findings suggest that despite an antagonistic relationship between Cin8p/Kip1p and Kar3p, aspects of their mitotic roles may be similar.

Alleles↗
PubMed1993

PcnB is required for the rapid degradation of RNAI, the antisense RNA that controls the copy number of ColE1-related plasmids.

The replication of ColE1-related plasmids is controlled by an unstable antisense RNA, RNAI, which can interfere with the successful processing of the RNAII primer of replication. We show here that a host protein, PcnB, supports replication by promoting the decay of RNAI. In bacterial strains deleted for PcnB a stable, active form of RNAI, RNAI*, which appears to be identical to the product of 5'-end processing by RNAase E, accumulates. This leads to a reduction in plasmid copy number. We show, using a GST-PcnB fusion protein, that PcnB does not interfere with RNAI/RNAII binding in vitro. The fusion protein, like PcnB, has polyadenylating activity and is able to polyadenylate RNAI (and also another antisense RNA, CopA) in vitro.

Ampicillin Resistance↗
PubMed1993

Mechanisms underlying chemoreceptor inhibition induced by atrial natriuretic peptide in rabbit carotid body.

1. Previous studies in our laboratory revealed the presence of atrial natriuretic peptide (ANP) in preneural chemosensory type I cells of the cat carotid body, and demonstrated that submicromolar concentrations of the peptide inhibited carotid sinus nerve (CSN) activity evoked by hypoxia. In the present study, we have evaluated the role of the cyclic nucleotide second messenger, cyclic GMP (cGMP), and the involvement of type I cells in rabbit chemosensory inhibition. 2. Submicromolar concentrations of the potent ANP analogue, APIII, greatly elevated both the content and release of cGMP from the carotid body. Denervation experiments confirmed earlier immunocytochemical studies which suggested that APIII-induced cGMP production occurs almost exclusively in type I cells; these experiments also indicate that both the sympathetic and sensory innervation to the carotid body exert a trophic influence on the metabolism of this second messenger. 3. Submicromolar concentrations of APIII inhibited the CSN activity evoked by hypoxia (79.8 +/- 3.2% (mean +/- S.E.M.) inhibition with 100 nM APIII) and nicotine (74.5 +/- 3.6% inhibition with 100 nM APIII), but did not affect basal CSN activity established in 100% O2-equilibrated superfusion solutions. 4. The biologically inactive analogue of ANP, C-ANP, failed to produce CSN inhibition; however, the inhibitory effects of APIII were mimicked by cell-permeant analogues of cGMP (dibutyryl-cGMP and 8-bromo-cGMP, 2 mM), which likewise did not alter basal CSN activity. Because we found that unmodified cGMP was an ineffective inhibitor of CSN activity, our data suggest that APIII inhibition is mediated intracellularly by cGMP produced within the type I cells. 5. APIII does not inhibit the CSN activity produced by 20 mM K+ (in zero Ca2+ media), which very probably results from direct depolarization of the sensory nerve terminals. 6. Catecholamine release from the carotid body evoked by hypoxia is likewise not altered by APIII (100 nM). 7. The data are consistent with the notion that APIII and analogues of cGMP alter the release of excitatory and/or inhibitory transmitters from chemosensory type I cells in the carotid body.

Animals↗
PubMed1993

The pcnB gene of Escherichia coli, which is required for ColE1 copy number maintenance, is dispensable.

The pcnB gene product of Escherchia coli is required for copy number maintenance of plasmids related to ColE1 and also for that of the IncFII plasmid R1. Because PcnB is similar to the tRNA-binding protein tRNA nucleotidyltransferase, we have suggested that the protein would be required only for processes in which an RNA is a prominent regulatory component. This appears to be so; strains deleted for pcnB, although defective in ColE1 and R1 plasmid maintenance, maintain the iteron-regulated plasmids F and P1 normally. We also find that strains deleted for pcnB grow normally, demonstrating that PcnB has no essential cellular role under the conditions tested and suggesting that regulation by antisense RNAs similar to RNAI has no critical role in any essential host process. We confirm by immunological tests that PcnB is likely to be the commercially available enzyme poly(A) polymerase.

Ampicillin↗
PubMed1993

[An experimental study on accelerating regeneration of meniscus with synovial flap implant in the rabbit knee].

Twenty-three rabbits were used in this study. In each animal the right knee was used for experimental group in which the synovial flap was implanted in after meniscectomy and the left knee for control group, in which only meniscectomy was done. Samples were collected 3, 6, 12, and 24 weeks after operation. The regenerated meniscus in two groups were evaluated grossly. Histologically by light microscopy, and subcellularly by transmission electron microscopy. It was showed that the regenerated meniscus of the experimental group were better than those of the control group both morphologically and qualitatively. In the experimental group fibrocartilage cells appeared 6 weeks after operation, cartilage cells became more mature at 12 weeks, and articular cartilage was normal at 24 weeks. The result shows that the synovial flap implant obviously accelerates the meniscus regeneration and has an affect on prevention articular cartilage from degenerating.

Animals↗
PubMed1993

[Expression of C-fos protein in CNS following electroacupuncture of the "quanliao" and the electrostimulation of the rat tail].

In this experiment, three groups were used to detect c-fos expression in the CNS in the awake male, S.D. rats, i.e, EA of "Quanliao" (14 Hz), electrostimulation of the rat tail (0.4-0.6 mA) and the control. Fos was identified by ABC immunohistochemical method. The results were as follows: I. The labelling cellular nuclei of pain group are in the laminae I, II, V, VII, and X of the spinal cord the medial part of the frontal cortex (FC) and that of the EA group were in the trigeminal nucleus and the lateral area of the FC. The number of the labelling nuclei (n) of EA group war more than that of the pain group in the rostral ventromedical medulla, the lateral reticular, the solitary n. the popiaqueductal grey, the parafacicular n, the centromedian n. and the subparafascicular n, of the thalamus. 2. The labelling nuclei of EA and pain groups appear commonly in the dorsal raphe n., the locus ceruleus, the periventricular n. of the thalamus, the hypothalamue, the lateral habenular n., and the septal area. In the control animals, in general, the labelled nuclei were sparsely seen.

Acupuncture Points↗
PubMed1993

[Memory function of patients with cerebral arteriosclerosis evaluated by Rivermead behavioural memory test].

Using Rivermead behavioural memory test, we examined 142 patients with cerebral arteriosclerosis. The results showed that the rate of anomalies of screening score in patients with cerebral arteriosclerosis were significantly higher than that of the control group (P < 0.01). The patients and control scores were significantly different (P < 0.05) in all items except the picture and face recognition. Comparing the screening score with brain CT scan, we found a relationship between brain damage and behavioural memory declination. Also, many persons of control group got low scores with behavioural memory test, suggesting that the Rivermead behavioural memory test be sensitive to memory declination. With its simplicity and sensitivity the Rivermead behavioural memory test may have some practical value in China.

Aged↗
PubMed1992

Effect of stem cell factor on in vitro erythropoiesis in patients with bone marrow failure syndromes.

Stem cell factor (SCF) enhances normal hematopoiesis. We examined its effect in vitro on bone marrow and blood progenitors from patients with inherited bone marrow failure syndromes, including 17 patients each with Diamond-Blackfan anemia (DBA) and Fanconi's anemia (FA), 3 with dyskeratosis congenita (DC), and 1 each with amegakaryocytic thrombocytopenia (amega) and transient erythroblastopenia of childhood (TEC). Mononuclear cells were cultured with erythropoietin (Ep) alone or combined with SCF or other factors. SCF increased the growth of erythroid progenitors in cultures from 50% of normal controls, 90% of DBA, 70% of FA, 30% of DC, and the amega and TEC patients; normal numbers were reached in 25% of DBA studies. Improved in vitro erythropoiesis with SCF in all types of inherited marrow failure syndromes does not suggest a common defect involving kit or SCF, but implies that SCF may be helpful in the treatment of hematopoietic defects of varied etiologies.

Adolescent↗