Biomedical subjects

Y Zhou

Publications and source records attributed to Y Zhou.

At least 19 recordsLinked to original sources

PubMed1996

Expression of rho A and rho kinase mRNAs in porcine vascular smooth muscle.

It has recently been indicated that rho A and rho kinase may be involved in the mechanism for the increase in Ca2+ sensitivity in smooth muscle myofilaments. In the present study, we investigated the mRNA expression of rho A and rho kinase in porcine vascular smooth muscle cells (aorta, coronary artery, pulmonary artery, and pulmonary vein). In reverse transcription-polymerase chain reaction (RT-PCR) experiments, using total RNA from these tissue specimens and the primers designed in the conserved regions of each mRNA in human and bovine, rho A and rho kinase mRNAs were detected in all of these smooth muscle cells. An analysis of these PCR products by direct sequencing indicated that they were derived from each mRNA. The finding that both rho A and rho kinase mRNAs were expressed in the various porcine vascular smooth muscle cells strongly supports the idea that these proteins are involved in the mechanism dealing with the increase in Ca2+ sensitivity in the myofilaments of vascular smooth muscle cells.

Amino Acid Sequence↗

PubMed1996

RNA transport to the vegetal cortex of Xenopus oocytes.

Xcat-2 RNA, a component of the germ plasm in Xenopus, localizes with the mitochondrial cloud material to the vegetal cortex in stage II oocytes. Vg1 RNA also localizes to the vegetal cortex, but later in stage III/IV oocytes, using a microtubule dependent pathway. To further analyze the mechanisms involved in RNA transport, in situ hybridization and autoradiography were used to follow the localization of endogenous Vg1 and injected Xcat-2 transcripts in stage IV oocytes. We show that Xcat-2 is competent to localize to the vegetal cortex quite independently of the mitochondrial cloud. Xcat-2 RNA appears to use the late Vg1 localization pathway, as depolymerization of microtubules by cold or nocodazole treatment prevented translocation of Xcat-2 transcripts, but did not result in the disruption of Xcat-2 anchored in the cortex. Furthermore, RNA transport was shown to be stage dependent for both Vg1 and Xcat-2 RNAs, as they did not localize in fully grown stage VI oocytes after injection. RNA sequences both required and sufficient to direct Xcat-2 to the vegetal cortex were mapped to a sequence of 150 nt immediately adjacent to the open reading frame and additional sequences at the end of the 3' untranslated region. Mapping was accomplished by injecting deletion mutant transcripts into stage IV oocytes and monitoring localization by RNase protection and autoradiography. All mutants competent for translocation were also capable of cortical anchoring, suggesting that the same signal is used for both steps. We speculate that two separate RNA pathways evolved during the course of Xenopus oogenesis. One pathway, specialized for the transport of germ plasm by way of the mitochondrial cloud, occurs early to ensure the segregation of the germ cell lineage. The other, late, pathway may serve as the more general transport system for localizing RNAs involved in somatic cell differentiation.

Animals↗

PubMed1996

ATP hydrolysis by membrane-bound Escherichia coli F0F1 causes rotation of the gamma subunit relative to the beta subunits.

We recently demonstrated that the gamma subunit in soluble F1-ATPase from Escherichia coli rotates relative to surrounding beta subunits during catalytic turnover (Duncan et al. (1995) Proc. Natl. Acad. Sci. USA 92, 10964-10968). Here, we extend our studies to the more physiologically relevant membrane-bound F0F1 complex. It is shown that beta D380C-F1, containing a beta-gamma intersubunit disulfide bond, can bind to F1-depleted membranes and can restore coupled membrane activities upon reduction of the disulfide. Using a dissociation/reconstitution approach with crosslinked beta D380C-F1, beta subunits containing an N-terminal Flag epitope (beta flag) were incorporated into the two non-crosslinked beta positions and the hybrid F1 was reconstituted with membrane-bound F0. Following reduction and ATP hydrolysis, reoxidation resulted in a significant amount of crosslinking of beta flag to the gamma subunit. This demonstrates that gamma rotates within F1 during catalytic turnover by membrane-bound F0-F1. Furthermore, the rotation of gamma is functionally coupled to F0, since preincubation with DCCD to modify F0 blocked rotation.

Adenosine Triphosphate↗

PubMed1996

Solid-phase synthesis of oligo-2-pyrimidinone-2'-deoxyribonucleotides and oligo-2-pyrimidinone-2'-deoxyriboside methylphosphonates.

A synthetic method was developed for the synthesis of oligodeoxyribonucleotides and oligodeoxyribonucleoside methylphosphonates comprised exclusively of the fluorescent 2-pyrimidinone base for the first time. The method utilized the solid-phase 2-cyanoethylphosphoramidite and methylphosphonamidite chemistry for internucleotide couplings and a baselabile oxalyl linkage to anchor the oligomers onto the CPG support. Cleavage of the oligomers from the support was effected by a short treatment of the support with 5% ammonium hydroxide in methanol at room temperature, without any degradation of the base-sensitive 2-pyrimidinone residues or the base-sensitive methylphosphonate backbone.

Molecular Structure↗

PubMed1996

Tissue specific expression of testis angiotensin converting enzyme is not determined by the -32 nonconsensus TATA motif.

Testis ACE is an isozyme of angiotensin-converting enzyme (ACE) made by male germ cells. These cells recognize a small intragenic promoter which contains a positive regulatory element, TCTTAT, at position -32. A probe containing this element was gel shifted to an identical location by rat testis and rat liver nuclear extracts; formation of the complex was blocked by anti-TATA binding protein antibody. Recombinant TATA binding protein recognized the testis ACE TCTTAT motif as well as a probe containing the consensus TATA motif. Mice transgenic for testis ACE promoter constructs containing either the wild type testis ACE motif or a consensus TATA sequence expressed a reporter gene at high levels only within the testis. These data suggest that the testis ACE motif TCTTAT is a non-consensus TATA, but is not responsible for the highly restricted pattern of testis ACE gene expression.

Animals↗

PubMed1996

Enhanced tumor suppressor gene therapy via replication-deficient adenovirus vectors expressing an N-terminal truncated retinoblastoma protein.

The preclinical studies presented here demonstrate that treatment of human non-small cell lung carcinoma and bladder carcinoma cells by a recombinant adenovirus vector, AdCMVpRB94, expressing the N-terminal truncated retinoblastoma (RB) protein (pRB94) completely suppressed the tumorigenicity of the treated tumor cells in nude mice. Furthermore, gene therapy of established human RB- and RB+ bladder xenograft cancers in nude mice by AdCMVpRB94 resulted in regression of the treated tumors. Of note, although both the full-length and the truncated forms of the RB protein, when overexpressed in tumor cells via replication-deficient adenovirus vectors, were capable of suppression of tumor growth, the pRB94 was evidently more potent than the full-length RB protein.

Adenoviruses, Human↗

PubMed1996

Genetic characterization of Clostridium botulinum type A containing silent type B neurotoxin gene sequences.

A recent study detected genes encoding type B botulinum neurotoxin in some type A strains of Clostridium botulinum that exhibit no type B toxin activity. In this study, we investigated the presence, structure, linkage, and organization of genes encoding botulinum neurotoxin (BoNT) and other components of the progenitor complex. Sequence analysis showed that the silent BoNT/B gene is highly related to that from authentic proteolytic type B C. botulinum. However, a stop signal and deletions were found within the sequence. A non-toxin nonhemagglutinin gene (NTNH) was mapped immediately upstream of both the BoNT/A and silent BoNT/B genes. Significantly the NTNH gene adjacent to the defective BoNT/B gene was "chimeric, " the 5'- and 3'-regions of the gene had high homology with corresponding regions of the type B NTNH gene, while the 471-amino acid sequence in the central region was identical to NTNH of type A. Hemagglutinin genes HA-33 and HA-II were not found adjacent to the NTNH/A gene, but instead there was an unidentified open reading frame previously reported in strains of C. botulinum types E and F. By contrast HA-II, HA-33, and NTNH genes were located immediately upstream of the silent BoNT/B gene. Pulsed-field gel electrophoretic analysis of chromosomal DNA digests indicated the distance between type A and B gene clusters to be less than 40 kilobases.

Amino Acid Sequence↗

PubMed1996

Corticotropin-releasing factor decreases vasogenic brain edema.

We report the first series of studies comparing the anti-edematous effects of human corticotropin-releasing factor (hCRF) and dexamethasone in an experimental model of vasogenic peritumoral brain edema. Both hCRF and dexamethasone effectively decreased blood-brain barrier (BBB) permeability of intracerebral RG2 gliomas in rats as observed by contrast-enhanced T(1)-weighted magnetic resonance imaging. A decrease in the water content of tumor and peritumoral brain tissue was observed with proton-density magnetic resonance imaging and confirmed by direct wet/dry tissue measurements. The calculated ED(50) for hCRF was 59 micrograms/kg s.c. twice a day, and that for dexamethasone was 0.61 mg/kg i.m. twice a day; the hCRF:dexamethasone dose-potency ratio was 120:1 on a molar basis. The anti-edematous action of hCRF is not mediated by the release of adrenal corticosteroids. A direct action of hCRF on the tumor microvasculature results in restoration of BBB integrity and up-regulation of BBB-specific protein expression. The average survival time with chronic treatment was prolonged significantly in the hCRF-treated group (35 days) compared with the dexamethasone-treated group (28 days; P < 0.05) and the saline-treated control group (22 days; P < 0.0001). hCRF, as an alternative to corticosteroid therapy, may provide substantial benefits with respect to reducing the major side effects encountered with long-term, high-dose corticosteroid treatment.

Adrenalectomy↗

PubMed1996

Antagonistic properties of centrally truncated analogs of [D-Trp(32)]NPY.

We have previously shown that [D-Trp(32)]NPY can competitively antagonize NPY-induced feeding in rats (Balasubramaniam et al. J. Med. Chem. 1994, 37, 811-815). This peptide, however, did not bind to SK-N-MC cells with Y-1 receptors. Since centrally truncated NPY analogs have been shown to bind Y-1 receptors, we synthesized similar analogs of [D-Trp(32)]NPY and investigated their Y-1 (SK-N-MC) and Y-2 (SK-N-BE2) receptor affinities and their properties in human erythroleukemia (HEL) cells. None of the analogs with D-Trp(32) mobilized intracellular calcium, [Ca2]i, in HEL cells. Although Des-AA(6-24)[Aoc(6)]NPY and the corresponding D-Trp(32) analog exhibited no affinity to Y-1 receptors, Des-AA(7-24)[Aoc(6),D-Trp(32)] NPY(6) exhibited weak binding. Replacing Pro(5) in 6 with D-Ala to stabilize the central chain reversal, and hence the antiparallel alignment of the N- and C-terminal regions known to be important for Y-1 binding, resulted in an analog, Des-AA(7-24)[D-Ala(5),Aoc(6),D-Trp(32)]NPY (7), which exhibited moderate antagonist potency in attenuating NPY effects on cAMP and [Ca2+]i, in SK-N-MC and HEL cells, respectively. This analog also shifted the dose-response curve of NPY on blood pressure in anesthetized rats. Deletion of only the 7-17 and/or the incorporation of N-Me-Ala(5), superior beta-turn stabilizer, in 7 did not improve the Y-1 receptor affinity. Des-AA(7-24)[D-Ala(5), Gly(6),D-Trp(32)]NPY exhibited an affinity similar to that of 7, suggesting that a long spacer arm is not necessary for efficient Y-1 receptor interaction. Locking the antiparallel alignment via a 2/26 or 2/27 lactam bridge did not improve the binding. Finally, replacement of D-Ala(5) in 7 with D-Trp dramatically increased both the binding and the antagonistic potencies. Modeling based on the avian pancreatic polypeptide X-ray structure suggested that analogs which have the N- and C-terminal regions in close proximity might exhibit good binding, and that the D-Trp(32) substitution may induce a beta-turn that could be important for exhibiting antagonism. A systematic investigation has resulted in the development of relatively potent Y-1 receptor antagonists. Further structure-activity studies with these compounds and those previously reported by us and other investigators should result in the development of long-acting and receptor selective antagonists.

Amino Acid Sequence↗

PubMed1996

Free radicals in the neurotoxic actions of beta-amyloid.

The fragment of the beta-amyloid protein that contains the peptide sequence 25 to 35 of the parent compound, increases cytosolic calcium and is directly cytotoxic to neurons in tissue culture. The cytotoxic action of beta-amyloid has been considered to be the primary determinant of the neurodegeneration observed in Alzheimer's disease. The cytotoxic effects of beta-amyloid 25-35 or beta-amyloid 1-40 added to primary cultures of rat hippocampal or cortical neurons can be reduced or prevented by anti-oxidant lazaroid drugs such as U-74500A, U-78517F, or U-83836E. beta-amyloid 25-35 evokes an immediate increase in cytosolic calcium when added to suspensions of PC 12 cells, and is cytotoxic to PC 12 cells in tissue culture. Both the calcium-elevating and the cytotoxic actions of beta-amyloid 25-35 on PC 12 cells are reduced or prevented by lazaroid anti-oxidant drugs. Since the lazaroids have been shown to scavenge free radical species, the present results indicate that the actions of beta-amyloid 25-35 on calcium regulation and on cell survival are mediated by free radicals.

Amyloid beta-Peptides↗

PubMed1996

Effects of the nitro-group on the mutagenicity and toxicity of some benzamines.

The Ames Salmonella/microsomal assay was employed to test the mutagenicity of some benzamines (aniline, and o- and p-phenylenediamine) and their nitro-derivatives (p-nitroaniline, 2-nitro-p-phenylenediamine, 3- and 4-nitro-o-phenylenediamine), using strains TA98 and TA100 and their nitroreductase-deficient mutants, TA98NR and TA100NR, in the presence and absence of rat S9 mix. The addition of the nitro-group to benzamine molecules converted them into direct mutagens. Furthermore, the position of the nitro-group affected their mutagenic activities. Cytotoxicity testing with Chinese hamster ovary cells (CHO-K1) showed that the presence of the nitro-group in these compounds had no specific effect on toxicity. The test compounds all showed a dose-related increase in inducing chromosomal aberrations in CHO cells. However, the presence of the nitro-group did not affect potency in inducing chromosomal aberrations. Compounds containing the nitro-group had higher initial oxidation potentials and dipole moments (mu) than their nonnitro-containing counterparts. The mutagenicity and toxicity of these compounds were not related to physico-chemical properties, including oxidation potential, energy difference (deltaE) between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO), ionization potential (I.P.), and mu.

Aniline Compounds↗

PubMed1996

Preliminary report on treatment of bone tumors with microwave-induced hyperthermia.

Between July, 1992, and February, 1995, 62 patients with various bone tumors were treated with microwave-induced hyperthermia. The series had 47 cases of malignant tumors and 15 cases with benign tumors; most of the tumors occurred at or near knee joints (53/62 = 85.4%). The surgical procedure consisted of separating the tumorous segment from surrounding normal tissues with a safe margin, cooling the normal tissues (including the vital neurovascular bundle and the intrajoint structures) with a water circulation system while heating the tumor simultaneously with the microwave antenna array, and providing an adequate soft-tissue cover for the dead bone. The tumor core temperature and the surface temperature reached 108 and 65 degrees C, respectively. The duration of microwave irradiation was usually 40-50 minutes. Meanwhile, the temperature of the normal tissues was kept under 39 degrees C. The minimal and maximal periods of clinical observation were 3 months and 36 months, respectively, and the mean follow-up period was 17 months. The 62 cases were evaluated from both oncological and orthopedic points of view. Five cases had local recurrence and required amputation. The 57 other cases had excellent local control. Six malignancy cases died of lung metastasis during a period of 1-2 years. Pathological fracture occurred at devitalized bone in five cases. In most of the cases, the knee joints functioned well, were stable and painless, and had almost full range of motion. Single-photon emission-computed tomography study in 16 cases revealed that revascularization of the devitalized tumorous bone segment could be accomplished in 1 year or more. These results show that the use of microwave hyperthermia for the treatment of bone tumors can be considered to be a definitive operation procedure that is safe and is well tolerated by patients. The oncological and orthopedic results are very encouraging.

Adolescent↗

PubMed1996

Hematologic profile and lymphocyte subpopulations in hemoglobin SC disease: comparison with hemoglobin SS and black controls. The Transfusion Safety Study Group.

Compared with subjects with homozygous SS disease (Hb SS), persons with hemoglobin SC (Hb SC) are known to have a more gradual loss of splenic function, a lower incidence of bacterial infections, and fewer end-organ failures. We studied hematological indices and lymphocyte subpopulations of 27 Hb SC subjects and compared them with 173 Hb SS patients and 131 black controls. Hb SC patients had higher hemoglobin levels than Hb SS subjects, lower total leukocyte, granulocyte, monocyte, and lymphocyte counts. Platelets decreased with age but not significantly, instead of increasing as among Hb SS patients. Mononuclear cells were generally similar to controls with the exception of CD8+HLA-DR+ counts resembling Hb SS. Hematologic changes in Hb SC are limited to moderate granulocytosis in children and adults, mild monocytosis in adults, and increased activation of just one lymphocyte subset among those measured.

Adolescent↗

PubMed1996

Differential expression of interleukin-5 mRNA+ cells and eosinophils in Nippostrongylus brasiliensis infection in resistant and susceptible strains of mice.

Interleukin (IL)-5 is produced by both T cells and eosinophils and has been implicated in lymphocyte and eosinophil differentiation and maturation. The extent to which differences in IL-5 expression contribute to genetic variability in parasite immunity was investigated by comparing eosinophilia, IgE production, mastocytosis and IL-5 mRNA+ cells following Nippostrongylus brasiliensis infection of resistant (BALB/c) and susceptible (C57BL/6) mice. In uninfected mice, IL-5 mRNA+ cells detected by in situ hybridization were distributed throughout the lamina propria and crypt regions of the small intestine in both strains, but were 1.5-fold higher in BALB/c than in C57BL/6 mice. Following N. brasiliensis infection, the numbers of IL-5 mRNA+ cells in BALB/c mice continued to increase until day 11 post-infection at which time they were more than 4-fold more numerous than in uninfected control mice of the same strain. In C57BL/6 mice, IL-5 mRNA+ cells reached peak numbers on day 7 post-infection, only 1.5-fold higher than uninfected controls, but the numbers began to decline thereafter. At all time points after day 5, the numbers of IL-5 mRNA+ cells in the gut of C57BL/6 mice were significantly lower than BALB/c mice. The differences in numbers of IL-5 mRNA+ cells induced by infection in each strain of mice correlated with changes in blood and intestinal eosinophilia, mastocytosis and IgE production and was reflected in differences in worm expulsion and egg counts. Although numbers of intestinal IgA-containing cells increased in both strains after infection, there was no difference between strains except at day 11 when there were significantly higher numbers in BALB/c mice than in C57BL/6 mice. These results suggest that IL-5 is an important regulatory factor determining host immunity to parasite infection and that differential regulation of IL-5 expression explains in part the observed strain differences with respect to parasite resistance.

Animals↗

PubMed1996

Concentration of rare earth elements, As, and Th in human brain and brain tumors, determined by neutron activation analysis.

Toxic elements As and Th, six rare-earth elemental profiles of brain tumor tissues from 16 patients of astrocytomas (grade I-III), and normal human brain tissues of 18 male, age-matched autopsies serving as controls have been studied by radiochemical neutron activation analysis. P-204 [di(2-ethylhexyl) phosphate] extraction chromatography column was used for group separation of rare-earth element (REE) by one step. Compared with the normal brain tissues, the analytical results showed that the concentrations of Th, La, Ce, Gd, and Lu were significantly higher in tumor tissues (P < 0.01 or 0.001). The possible effects of REE on tumor cell were discussed.

Adult↗

PubMed1996

Regulation of kappa opioid receptor mRNA in the rat brain by "binge' pattern cocaine administration and correlation with preprodynorphin mRNA.

We previously reported that 'binge' pattern administration of cocaine elevates preprodynorphin (ppDyn) mRNA in the caudate-putamen of rats. The present study confirms this finding. In addition, we report here that "binge' pattern administration of cocaine leads to a significant decrease in the mean level of kappa opioid receptor (KOR) mRNA in the substantia nigra, with no significant change in the mean level of KOR mRNA in the caudate-putamen. The decrease in KOR mRNA in the substantia nigra after 3 day or 14 day 'binge' administration of cocaine was comparable to the increase in ppDyn mRNA in the caudate-putamen. While there was no significant change in the mean levels of KOR mRNA in the caudate-putamen following cocaine administration, there was a positive within animal correlation between the levels of ppDyn mRNA and KOR mRNA in the caudate-putamen, both in animals administered saline and in animals receiving 'binge' cocaine for 14 days. Finally, mean levels of ppDyn or KOR mRNA in cocaine treated rats were not different from saline treated controls following a 10 day withdrawal from 14 days of 'binge' cocaine administration. The results provide evidence of regulation of KOR mRNA by cocaine in the substantia nigra.

Animals↗

PubMed1996

Modulation of CRF-R1 mRNA in rat anterior pituitary by dexamethasone: correlation with POMC mRNA.

Glucocorticoids have been shown to decrease CRF receptor binding in the anterior pituitary. To determine whether glucocorticoids or CRF peptide modulate CRF-R1 gene expression, CRF-R1 mRNA levels in rat pituitary and brain were measured after administration of a synthetic glucocorticoid, dexamethasone (DEX) or rat/human CRF (r/hCRF), using a sensitive solution hybridization RNase protection assay. DEX (400 micrograms/day) or r/hCRF (100 micrograms/kg/day) was administered twice daily for 5 days to male rats. DEX treatment caused a significant decrease in CRF-R1 mRNA levels in the anterior pituitary. Also, a significant positive correlation was found between CRF-R1 and POMC mRNA levels in the anterior pituitary of the individual animals: levels of both mRNAs were reduced by DEX. However, r/hCRF treatment had no significant effect on CRF-R1 mRNA levels in the anterior pituitary. In extrahypothalamic brain regions, mRNA levels of CRF-R1 did not change following either DEX or r/hCRF administration. Our data suggest that in addition to POMC and CRF genes, CRF-R1 gene may also be subject to negative feedback control by glucocorticoids.

Amygdala↗

PubMed1996

Toxigenic molds in water-damaged buildings: dechlorogriseofulvins from Memnoniella echinata.

An investigation of a cluster of cases of pulmonary hemosiderosis in infants in Cleveland, OH, led to the isolation of many isolates of Stachybotrys atra and two isolates of a related toxigenic fungus, Memnoniella echinata. M. echinata produces two cytotoxic trichothecene mycotoxins, trichodermol (1a) and trichodermin (1b), as well as several griseofulvins. Dechlorogriseofulvin (2a) and epidechlorogriseofulvin (2b) were the major compounds isolated. This is the first report of a fungus outside the Penicillium genus producing griseofulvins.

Griseofulvin↗