Biomedical subjects
Publications and source records attributed to H He.
Silver was absorbed by cotton cellulose xanthate in solution at pH 6, and was eluated quantitatirely from CCX with 3% HNO3 solution and determination by FAAS. The method is simple and rapid and has been apllied to the determination of silver in rocks and water.
We performed the present study to determine 1) whether different organs undergo similar increase in vascular resistance in Dahl-Iwai salt-sensitive (S) rats, and 2) the effects of chronic oral L-arginine supplementation on the regional hemodynamics in S rats. Male 6 week old S rats and Dahl-Iwai salt-resistant (R) rats were maintained on an 8% NaCl chow for 4 weeks. One group (S or R rats) was maintained on tap water and the other group (S/Arg) of S rats received tap water containing L-arginine at a concentration of 1.5%. Organ blood flow and cardiac output were measured with microspheres in the conscious condition. Concerning regional hemodynamics, the flow rate of the kidney was lower in S rats than in R rats, but there were no differences between S and R rats in the flow rates of the brain, heart, lung, liver, spleen, intestine, skeletal muscle and skin. The flow rate of the kidney in S/Arg rats was maintained at a higher level as compared to that of S rats. Urinary excretion of protein and albumin in S/Arg rats was significantly suppressed when compared to S rats. Thus, the supplementation of L-arginine normalized the abnormality of renal hemodynamics accompanying salt-induced hypertension. It is suggested that the disturbance in the production of nitric oxide may induce salt-sensitive hypertension and the abnormality of renal hemodynamics in the S rats.
Both HS1 (hematopoiesis specific) and EMS1/ cortactin belong to a growing family of cytoskeletal SH3 proteins. Most proteins in this family, except for alpha-spectrin, contain a single SH3 domain at the C-terminus, and an F-actin binding domain (s) at the N-terminus. The main reason why EMS1 initially attracted great attention among molecular oncologists is the amplification and over-expression of EMS1 gene in mammary tumors. However, our recent study on HS1 suggests that EMS1 is a tumor suppressor rather than a proto-oncoprotein. First of all, full-length HS1 of 486 amino acids suppresses the malignant transformation caused by oncogenic Ras mutants such as v-Ha-Ras. Second, for its anti-oncogenicity, HS1 requires the C-terminal SH3 domain, and the N-terminal actin-binding motifs, in addition to two phosphorylatable Tyr residues at positions 378 and 397. Third, EMS1 shares with HS1 80% sequence identity in the C-terminal SH3 domain, and 70% identity in the N-terminal actin-binding motifs, and contains these two Tyr residues, all of which are required for the anti-oncogenicity of HS1. Lastly, overexpression of EMS1 does not transform normal cells, and rather disfavors their growth. Among several actin-binding tumor suppressors, HS1 is the first tumor suppressor whose actin-binding has been shown to be essential for its anti-oncogenicity.
SETTING: Cross-sectional study of drug users recruited from street-based settings in four US cities: Denver, Portland, Oakland and San Francisco. OBJECTIVE: To evaluate responses to two-step tuberculin skin testing among HIV-positive and HIV-negative injection drug users. DESIGN: Subjects were recruited from existing studies of HIV and risk behaviors for tuberculin skin testing. Those with a negative initial tuberculin test were referred for a second skin test 1-3 weeks later. A positive tuberculin test was defined as > or = 10 mm, or > or = 5 mm if the subject was HIV-positive. RESULTS: Of 997 persons receiving an initial tuberculin test, 13% had a positive response. Of 644 persons receiving a second tuberculin test, 8% had a positive response, with rates as high as 14% among those from Oakland and 12% among African Americans. HIV-positive subjects were less likely to have skin test responses > or = 10 mm on the initial test (P = 0.03), or increases between the initial and second test of > or = 10 mm (P = 0.06). CONCLUSION: Boosting occurred in both HIV-positive and HIV-negative injection drug users. Two-step testing should be considered for this population, particularly those on whom repeat tuberculin testing will be performed.
To establish a ELISA method to detect the infection of human immunodeficiency virus (HIV), we synthesized nine peptides ranging in length between 10-27 amino acid (aa) of HIV located in the regions of gp41, p24 of HIV-1 and gp36 of HIV-2, according to the published amino acid sequence and the position of antigenic determinants of viruses, by a solid-phase method. We detected 10 positive sera of HIV-1 and 4 positive sera of HIV-2 by a indirect ELISA using these synthetic peptides as the coating antigen. The results indicated that all of 10 serum specimens of HIV-1 were positive using SP1, 5, 6, and 7 derived from gp41, and SP7 was the best in antigenicity. The 4 serum specimens of HIV-2 were positive using SP8 and SP9 in the region of gp36 and their antigenicity to HIV-2 were similar, but the antigenicity of SP8 to HIV-1 was higher than that of SP9. All sera of HIV-1 and HIV-2 were positive using SP7 and SP8 as the mixed coating antigen. A comparison of our reagent with UBI reagent in detection of 60 positive and 96 negative control sera for HIV showed that the coincident rate for positive ness was 98.33% (59/60), for negative ness was 100%, and the general coincident rate was 99.36% (155/156). It is concluded that SP7 and SP8 as the mixed coating antigen are applicable in the diagnosis of HIV infection.
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This paper identifies two structural proteins of the occluded derived viral envelope of Autographa californica nuclear polyhedrosis virus (AcMNPV): ODV-E18 and ODV-E35. In addition, we identify a protein, ODV-EC27, that is incorporated into the capsid of occluded virus, which is not detected in budded virus. The genes for these proteins reside within the IE0 intron. The intron was sequenced, and five open reading frames (ORF) were identified. ORF 3 (genomic ORF 143) codes for the ODV envelope protein, ODV-E18. ORF 4 (genomic ORF 144) codes for ODV-EC27, and Western blot analyses locate this protein to both the ODV capsid and envelope. Transcripts for both ODV-E18 and ODV-EC27 initiate from conserved TAAG motifs, and transcripts are detected from 16 through 72 hr p.i. Antiserum to ODV-E18 recognizes a band of 18 kDa on Western blots of extracts from infected cells and bands of 18 and 35 kDa on Western blots of proteins from purified ODV envelope. N-terminal amino acid sequencing reveals that both ODV-E18 and ODV-E35 contain the same N-terminus. Antiserum to ODV-EC27 recognizes a protein of 27 kDa on Western blots of extracts from infected cells and bands of 27 and 35 kDa on Western blots of proteins from purified ODV. Using immunogold labeling techniques, ODV-E18 and/or ODV-E35 are detected in viral induced intranuclear microvesicles and are not detected in the plasma membrane, cytoplasmic membranes, or the nuclear envelope. Immunogold labeling using antisera to ODV-EC27 detects this protein on both the ODV envelope and capsid.
T cell activation requires at least two distinct signals, including signaling via the Ag-specific TCR and a costimulatory pathway. The best characterized costimulatory pathway involves the CD28 molecule, which is expressed constitutively on T cells and binds the family of B7 counter-receptors on APCs. Inhibition of this costimulatory pathway prevents T cell activation and can lead to long-term T cell unresponsiveness or anergy. In contrast, CTLA4, which is homologous to CD28, has been shown to be a negative regulator of T cell activation. The CTLA4 molecule is not expressed on resting T cells, but is induced after the initial steps of T cell activation. To address the regulation of CTLA4 expression, we have analyzed CTLA4 at the level of cell surface expression, mRNA, rate of transcription, and rate of decay of message. Nuclear runoff results show an increase in the rate of transcription following T cell activation. Our analyses of non-T cells, including B cells, mastocytoma, and fibroblasts, by Northern blot analysis detect only T cell expression of CTLA4. Reporter gene analysis indicates that 335 bp of upstream CTLA4 sequence are sufficient to control inducibility. We have identified important regulatory regions that control inducible and cell-specific CTLA4 expression. These results also suggest that both positive and negative response elements modulate the transcriptional regulation of CTLA4 gene expression. Understanding the regulation of CTLA4 should provide insight into the regulation of T cell activation at the molecular level.
Haemorrhagin IV, a medium molecular weight haemorrhagin from the snake venom of Agkistrodon acutus (AaHIV), has been purified and crystallized. The molecular weight and isoelectric point of AaHIV are 44 kDa and pI 5.0, respectively. The crystal belongs to space group C222(1) with unit-cell dimensions of a = 124.2, b = 114.5, c = 98.4 A, and could o diffract X-rays to 3.0 A, resolution. There are one or two molecules in the crystallographic asymmetric unit.
Regional hemodynamic responses to the vasodilators, hydralazine (1 mg/kg, i.v.) and verapamil (0.1 mg/kg/min, i.v.), were examined in conscious Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR), 15 and 50 weeks of age, using the radioactive microsphere method. The flow rates of heart and skeletal muscle in SHR were higher than those in WKY, and the flow rates of liver, kidney, intestines, and skin in SHR were lower than those in WKY. These differences between the regional blood flow in WKY and SHR were observed in both aged and young rats. The changes in organ blood flow induced by hydralazine and verapamil were similar for WKY and SHR in most organs. Both drugs increased the skeletal muscle blood flow in WKY and young SHR, but not in aged SHR, that is, the skeletal muscle blood vessels in aged SHR lost their vasodilatory response. These results suggest that, although a lack of vasodilatory responses in the skeletal muscle vasculature of aged SHR may be triggered by persistent hypertension, the vital organ vasculature maintains its normal vasodilating capacity.
We have previously reported that vasopressin (AVP) V2 receptor stimulation increased renal blood flow in dogs anesthetized with pentobarbital. In this study, we examined the direct effects of AVP on afferent arterioles to clarify the role played by V2 receptors in regulating afferent arteriolar tone. We microdissected a superficial afferent arteriole with glomerulus from the kidney of a New Zealand White rabbit. Each afferent arteriole was cannulated with a pipette system and microperfused in vitro at 60 mm Hg. The effects of vasoactive substances were evaluated by changes in the lumen diameter of afferent arterioles. We found that AVP decreased the lumen diameter of microperfused afferent arterioles dose-dependently and that a V1 antagonist, OPC21268, inhibited the vasoconstrictor action of AVP. However, AVP 10(-8) M increased the lumen diameter of norepinephrine (NE)-constricted afferent arterioles pretreated with OPC21268 (OPC + NE, 8.2 +/- 0.7 microns; OPC + NE + AVP, 9.9 +/- 0.9 microns*; *P < 0.05, N = 13). This vasodilatory effect of AVP was abolished by pretreatment with a V2 antagonist, OPC31260. Desmopressin (dDAVP), a V2 agonist, increased the lumen diameter of the NE-constricted afferent arterioles (NE, 7.4 +/- 0.9 microns; NE + dDAVP, 10.1 +/- 0.7 microns*; *P < 0.05, N = 9). These results suggest that AVP V2 receptors are present in rabbit afferent arterioles and that V2 receptor stimulation induces vasodilation in rabbit afferent arterioles.
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Bacillus cereus UW85 produces two antibiotics that contribute to its ability to suppress certain plant diseases (L. Silo-Suh, B. Lethbridge, S. J. Raffel, H. He, J. Clardy, and J. Handelsman, Appl. Environ. Microbiol. 60:2023-2030, 1994). To enhance the understanding of disease suppression by UW85, we determined the chemical structure, regulation, and the target range of one of the antibiotics. The antibiotic was identified as 3-amino-3-deoxy-D-glucose, also known as kanosamine. Kanosamine was highly inhibitory to growth of plant-pathogenic oomycetes and moderately inhibitory to certain fungi and inhibited few bacterial species tested. Maximum accumulation of kanosamine in B. cereus UW85 culture supernatants coincided with sporulation. Kanosamine accumulation was enhanced by the addition of ferric iron and suppressed by addition of phosphate to rich medium. Kanosamine accumulation was also enhanced more than 300% by the addition of alfalfa seedling exudate to minimal medium.
Na-K-ATPase alpha 3-subunit mRNA levels are both positively and negatively controlled by thyroid hormone [3,5,3'triiodothyronine (T3)] in primary cultures of neonatal rat cardiac myocytes. In this study, transient transfection analysis indicated that two regions of the rat alpha 3 gene between nucleotides -116 and -6 and -6 and +80 conferred T3-mediated inhibition of reporter gene expression. Electrophoretic mobility shift assays showed specific binding of T3 receptor monomers and T3 receptor-retinoid X receptor heterodimers at each alpha 3 gene negative T3-response region. The alpha 3 gene region from -116 to -6 base pairs also mediates repression in response to retinoic acid (RA) and binds RA receptor. In the absence of ligand, reporter gene expression driven by the -116 to -6-base pair region is repressed with cotransfection of T3 receptor, whereas it is unaffected by overexpression of RA receptor. These data demonstrate that the proximal promoter of the rat Na-K-ATPase alpha 3 gene contains sequence motifs that mediate repression of alpha 3 gene transcription in response to either T3 or RA in neonatal rat cardiac myocytes.
To elucidate the role of apoptosis in the pathological lesion of hepatitis B virus (HBV) infection, biopsied liver tissue specimens of 38 patients with chronic hepatitis B of varying severity were investigated with in situ immunohistochemistry and TUNEL test. Apoptotic hepatocytes were found to be rare, while the nuclei of many cells were positively stained with TUNEL, suggesting 3'-OH ends generated as the DNA was impaired. Of the 17 cases with mild lesion or without piecemeal necrosis, 14 were negative or weakly positive with both Fas and TUNEL test. Of the 7 cases with piecemeal and bridging necrosis, none was strongly positive. In the 14 cases with active hepatitis and early cirrhosis, strongly positive results with Fas were found in 9 and with TUNEL in 3 respectively. It is suggested that the cytotoxic T lymphocyte (CTL)-Fas-apoptosis mechanism was involved in the hepatocyte death of hepatitis B as well. The Fas expression, DNA damage and apoptotic cells distributed mostly in the piecemeal necrosis region, and the ballooning and the necrotic hepatocytes were also clustering in this region. As both the apoptosis and necrosis are mediated by CTL, they are closely related: while transducted by different ways, they occurred independently.
The second experiment of protein crystallization was performed on domestic re-entry satellite FSW-2 in 1994-07. The results are superior to the ones of the first mission in 1992: 9 of 10 different proteins were crystallized in space, and 70% of the total 48 samples yielded single crystals. Besides hen egg-white lysozyme which grew high-quality crystals on the first mission, an acidic phospholipase A2(aPLA2) from snake venom and hemoglobin from Anser Indicus produced good-quality crystals suitable for X-ray diffraction analyses. The positive effect of microgravity on protein crystal growth is verified again at this time.
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