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Biomedical subjects

W Wu

Publications and source records attributed to W Wu.

At least 343 records · Page 19Linked to original sources
PubMed1996

Synthesis of heterocycles containing two cytosine or two guanine base-pairing sites. Novel tectons for self-assembly.

The synthesis of 1 and 2 is described, as is the X-ray structure of 1. Tecton 1 contains two DAA hydrogen bonding sites (cytosine-like), while 2 contains two DDA sites (guanosine-like). Tectons 1 and 2 were designed to self-assemble into a helical superstructure. Self-recognition of 1 occurs in the solid state with a novel inclusion of dimethylacetamide solvent.

Crystallography, X-Ray↗
PubMed1996

Daily and hourly temporal association between delta4-androstenedione-induced preterm myometrial contractions and maternal plasma estradiol and oxytocin concentrations in the 0.8 gestation rhesus monkey.

OBJECTIVE: Our purpose was to investigate the temporal relationship between delta4-androstenedione-induced preterm switching of myometrial activity patterns from contractures to contractions and maternal plasma estradiol and oxytocin concentrations in the 0.8 gestation rhesus monkey. STUDY DESIGN: Eight rhesus monkeys (132 to 136 days' gestation) were instrumented under halothane with femoral artery and vein catheters and uterine electromyogram electrodes. At 138 to 142 days' gestation baseline maternal femoral artery blood samples for estradiol and oxytocin measurement were taken at 30-minute intervals for 7 hours, starting 2 hours before the onset of darkness. The day after baseline sampling a continuous intravenous delta4-androstenedione infusion (0.3 mg . kg-1 .hr-1 in 10% intralipid at 0.25 ml . hr-1) was started in four monkeys, while four monkeys were infused intravenously with intralipid alone. The sampling regimen was then repeated at 1 and 3 days after the start of the delta4-androstenedione or intralipid infusion. Contractions were counted and estradiol and oxytocin were measured by radioimmunoassay. RESULTS: Androstenedione promoted a premature nocturnal increase in myometrial contractions in conjunction with an increase in maternal plasma concentrations of estradiol and oxytocin, which were of similar magnitude to those measured in spontaneous term labor. The increase in maternal estradiol preceded the increase in maternal oxytocin levels and myometrial contractions. The onset of the increase in maternal plasma oxytocin was closely associated with the appearance of myometrial contractions after delta4-androstenedione treatment. In contrast, no sustained premature contractions or changes in estradiol and oxytocin occurred in intralipid-treated monkeys. CONCLUSIONS: We conclude that in the 0.8 gestation rhesus monkey (1) the increase in maternal plasma estradiol precedes the increase in maternal plasma oxytocin after delta4-androstenedione treatment and (2) delta4-androstenedione-induced preterm myometrial contractions are closely associated in time with physiologic increases in maternal plasma oxytocin concentrations.

Analysis of Variance↗
PubMed1996

A solitary congenital self-healing histiocytosis. Report of a case and review of the literature.

Congenital self-healing histiocytosis (CSHH), and especially the solitary variant, is a rare primary skin disorder. We report on a newborn with a congenital solitary ulcerated skin nodule. Extracutaneous involvement was not found. A skin biopsy was performed at the age of 44 days and revealed a dense dermal infiltrate of large histiocytic cells. Immunohistochemical study revealed that the cells of the dermal infiltrate were Langerhans' cells which were strongly positive for S- 100 and negative for lysozyme, leukocyte common antigen and alpha-1-antichymotrypsin. The skin lesion involuted spontaneously over the next month without any treatment. The clinical, histopathological and immunohistochemical results fulfilled the criteria of solitary CSHH. We herein report the first case of CSHH in Taiwan and the twelfth case of solitary CSHH in the world.

Histiocytosis↗
PubMed1996

Effect of C-peptide administration on whole body glucose utilization in STZ-induced diabetic rats.

Recent studies suggest that C-peptide stimulates glucose transport in isolated skeletal muscle. In order to determine the effect of C-peptide on whole body glucose utilization, streptozotocin (60 mg kg-1) (STZ)-induced diabetic and normal rats were studied using the euglycaemic clamp procedure and continuous infusion of somatostatin (1.0 micrograms kg-1 min-1) in pentobarbital-anaesthetized rats. Plasma insulin levels during the 6.0- and 30.0-mU kg-1 min-1 insulin infusions rose to 70-90 microU mL-1 and 500-700 microU mL-1, respectively. Blood glucose concentrations were clamped at 7.5-7.9 mmol L-1 in the diabetic rats and at basal levels or 7.7 mmol L-1 in the non-diabetic (normal) rats. Biosynthetic human C-peptide (0.5 nmol kg-1 min-1) was infused in 12 diabetic and 11 normal rats, resulting in concentrations of 26-41 nmol L-1. The metabolic clearance rate of glucose (MCR) for the diabetic rats receiving C-peptide (12.0 +/- 1.0 mL kg-1 min-1) was significantly (P < 0.01) higher than that in the diabetic rats given saline (6.3 +/- 0.7 mL kg-1 min-1) or a randomly scrambled C-peptide (7.8 +/- 1.3 mL kg-1 min-1) at low-dose insulin infusion but not at the high-dose insulin infusion. In normal rats C-peptide did not significantly increase the MCR for glucose. These results thus demonstrate that C-peptide has the capacity to increase glucose utilization in STZ-induced diabetic rats.

Animals↗
PubMed1996

Variation in expression of hsp27 messenger ribonucleic acid during the cycle of the seminiferous epithelium and co-localization of hsp27 and microfilaments in Sertoli cells of the rat.

The purpose of these studies was to define expression of hsp27 mRNA during the cycle of the seminiferous epithelium and to determine the distribution of hsp27 protein in the rat testis. To study hsp27 mRNA expression, a rat hsp27 cDNA was isolated and sequenced (GenBank no. M86389). The cDNA was used in Northern blot analysis to estimate the relative levels of hsp27 mRNA in rat seminiferous tubule segments selected for different stages of the cycle of the seminiferous epithelium. The level of hsp27 mRNA was low during stages IX-XII of the cycle of the seminiferous epithelium. Approximately 15-fold higher levels of hsp27 mRNA were expressed during stages II-VI, with intermediate levels being expressed during stages XIII-I and VII-VIII. No effect of FSH on hsp27 mRNA expression was detected in cultured Sertoli cells, suggesting that hsp27 synthesis in Sertoli cells is not directly regulated by FSH. The distribution of hsp27 was also studied by use of immunofluorescence in frozen sections of rat testis, in isolated seminiferous tubules, in primary cultures of Sertoli cells isolated from 19-26-day-old rats, in peritubular myoid cells from 26-day-old rats, and in several cell lines. Microfilaments were localized in similar preparations by using rhodamine-phalloidin or BODIPY-phallicidin (Molecular Probes, Eugene, OR). The hsp27 was co-localized with micro-filaments in Sertoli cells from 20-day-old and older rats, but not in Sertoli cells from younger rats. In other cell types, hsp27 was diffusely distributed throughout the cytoplasm. These results demonstrate that hsp27 expression varies with the cycle of the seminiferous epithelium and provide the first direct morphological evidence that hsp27 is associated with microfilaments in a normal, intact tissue. They also suggest that Sertoli cell micro-filaments, by virtue of their associated hsp27, may be different in composition and function from microfilaments of peritubular myoid cells and many other cell types.

Actin Cytoskeleton↗
PubMed1996

Ondansetron blocks nifedipine-induced analgesia in rats.

The serotonergic system is involved in pain transmission and the 5-hydroxytryptamine (5-HT3) receptor subtype mediates some of these effects at the spinal level. Therefore, we explored the effects of the serotonergic system on nifedipine-induced analgesia by using the 5-HT3 receptor antagonist ondansetron. Male Sprague-Dawley rats were pretreated with ondansetron (1 mg/ kg intraperitoneally) or normal saline. After 15 min, rats received injections of nifedipine (15 mg/kg intraperitoneally) or dimethylsulfoxide (DMSO), solvent for nifedipine, as a control. Nociception was assessed by tail-flick method. Rats treated with nifedipine alone had an increase in tail-flick latency of 122%, as measured by the area under the curve, compared to rats treated with DMSO alone. Pretreatment with ondansetron, however completely blocked the analgesic effect of nifedipine, with tail-flick latency remaining at baseline throughout the measurement period. These results indicate that the 5-HT3 receptor plays an important role in the analgesic response to nifedipine and that medications that block this receptor may decrease the analgesic effectiveness of this type of therapy.

Analgesia↗
PubMed1996

Formation of Fatty Acid-degrading, anaerobic granules by defined species.

An endospore-forming, butyrate-degrading bacterium (strain BH) was grown on butyrate in monoxenic coculture with a methanogen. The culture formed dense aggregates when Methanobacterium formicicum was the methanogenic partner, but the culture was turbid when Methanospirillum hungatei was the partner. In contrast, a propionate-degrading, lemon-shaped bacterium (strain PT) did not form aggregates with Methanobacterium formicicum unless an acetate-degrading Methanosaeta sp. was also included in the culture. Fatty acid-degrading methanogenic granules were formed in a laboratory-scale upflow reactor at 35(deg)C fed with a medium containing a mixture of acetate, propionate, and butyrate by using defined cultures of Methanobacterium formicicum T1N, Methanosaeta sp. strain M7, Methanosarcina mazei T18, propionate-degrading strain PT, and butyrate-degrading strain BH. The maximum substrate conversion rates of these granules for acetate, propionate, and butyrate were 43, 9, and 17 mmol/g (dry weight)/day, respectively. The average size of the granules was about 1 mm. Electron microscopic observation of the granules revealed that the cells of Methanobacterium formicicum, Methanosaeta sp., butyrate-degrading, and propionate-degrading bacteria were dispersed in the granules. Methanosarcina mazei existed inside the granules as aggregates of its own cells, which were associated with the bulk of the granules. The interaction of different species in aggregate formation and granule formation is discussed in relation to polymer formation of the cell surface.

Journal Article↗
PubMed1996

Human immunodeficiency virus type 1 nucleocapsid protein reduces reverse transcriptase pausing at a secondary structure near the murine leukemia virus polypurine tract.

In an earlier study on minus-strand DNA synthesis catalyzed by murine leukemia virus reverse transcriptase, we described a prominent pause site near the polypurine tract (J. Guo, W. Wu, Z. Y. Yuan, K. Post, R. J. Crouch, and J. G . Levin, Biochemistry 34:5018-5029, 1995). We now report that pausing at this site is due to a stem-loop structure in the RNA template, formed by interaction of a number of bases in the polypurine tract, including the six G's, and a 3' sequence which includes four C's. Addition of human immunodeficiency virus type 1 (HIV-1) nucleocapsid (NC) protein to reverse transcriptase reactions reduces pausing by approximately 8- to 10-fold and stimulates synthesis of full-length DNA. Thus, NC functions as an accessory protein during elongation of minus-strand DNA and increases the efficiency of DNA synthesis, in this case, by apparently destabilizing a region of secondary structure in the template. Since NC is associated with genomic RNA in the viral core and is likely to be part of a viral replication complex, these results suggest that NC may also promote efficient DNA synthesis during virus replication. Mutational analysis indicates that the features of HIV-1 NC which are important for reduction of pausing include the basic amino acids flanking the first zinc finger, the zinc fingers, and the cysteine and aromatic amino acids within the fingers. These findings suggest that reverse transcription might be targeted by drugs which inactivate the zinc fingers of HIV-1 NC.

Amino Acid Sequence↗
PubMed1996

Fast spin-echo MR assessment of patients with poor outcome following spinal cervical surgery.

PURPOSE: The aim of the investigation was to evaluate poor outcome following spinal and cervical surgery. MATERIAL AND METHODS: A total of 146 consecutive patients operated with anterior discectomy and fusion (ADF) with the Cloward technique were investigated. Clinical notes, plain radiography, CT, and fast spin-echo (FSE) images were retrospectively evaluated. RESULTS: Some 30% of the patients had unsatisfactory clinical results within 12 months after surgery; 13% had initial improvement followed by deterioration of the preoperative symptoms, while 14.4% were not improved or worsened. Disc herniation and bony stenosis above, below, or at the fused level were the most common findings. In 45% of patients, surgery failed to decompress the spinal canal. In only 4 patients was no cause of remaining myelopathy and/or radiculopathy found. FSE demonstrated a large variety of pathological findings in the patients with poor clinical outcome after ADF. Postoperatively, patients with good clinical outcome had a lower incidence of pathological changes. CONCLUSION: FSE is considered the primary imaging modality for the cervical spine. However, CT is a useful complement in the axial projection to visualize bone changes.

Adult↗
PubMed1996

Degenerative changes following anterior cervical discectomy and fusion evaluated by fast spin-echo MR imaging.

PURPOSE: To review pre- and postoperative fast spin-echo (FSE) MR images of disc herniation and spondylosis in patients after spinal cervical surgery. MATERIAL AND METHODS: Data were reviewed of 68 patients after anterior discectomy and fusion (ADF) operations using the Cloward technique with solid single level (C5-C6 or C6-C7) or 2-level fusions (C5-C7). The average interval from surgery to review was 37 months. Age- and sex-matched controls without neck problems were examined. RESULTS: Preoperatively, the fusion groups had a higher incidence of protruded disc, and anterior and posterior osteophytes at the levels to be fused than the controls. Post-operatively, there was a significantly higher incidence of posterior osteophytes at the fused levels compared with the controls. Furthermore, the disc herniations and anterior osteophytes at the levels above and below the operated segments were more frequent in the fusion group. CONCLUSION: ADF causes acceleration of the degenerative changes at the fused level and at the levels below and above the fused segments.

Case-Control Studies↗
PubMed1996

Wortmannin inhibits the production of reactive oxygen and nitrogen intermediates and the killing of the Saccharomyces cerevisiae by isolated chicken macrophages.

The direct effects of wortmannin (0 to 1280 nM) on several functions in cultured macrophages isolated from Sephadex-elicited Leghorn chicken peritonea were studied. Under concentrations not affecting cell viability, wortmannin, as low as 5 nM, inhibited lipopolysaccharide (LPS)-induced nitric oxide production (P < 0.01). However, wortmannin (as high as 1280 nM) exposure 5 hours post LPS induction had no effect on nitric oxide production in macrophages, indicating a blockade of LPS-induction of a signaling pathway related to nitric oxide formation. Phorbol myristate acetate (PMA)-induced superoxide production was only inhibited (P < 0.001) by concurrent exposure to 1280 nM wortmannin. Prior exposure to 160 nM and higher of wortmannin for 24 hours reduced the average number of yeast cells ingested by or attached to a single macrophage (P < 0.001) and the ability of the macrophage to kill the baker's yeast (P < 0.05), while wortmannin itself did not affect the yeast. These data provide direct evidence for macrophages being the target cell of wortmannin and further support the notion that impaired macrophage functions are responsible for the immunosuppressive effect of wortmannin previously observed in birds.

Androstadienes↗
PubMed1996

[The inhibitory effects of serum of patients with acute promyelocytic leukemia on the formation of megakaryocytopoiesis colony unit].

OBJECTIVES: To determine if the sera of patients with acute promyelocytic leukemia (APL) and all-trans retinoic acid (ATRA) inhibit the formation of colony-forming-unit of megakaryocyte (CFU-Meg). METHODS: By cellular culture assay, the sera of 22 APL patients treated with ATRA and 10(-6)' mol/L ATRA were kinetically used to perform the investigation. Meanwhile, serum tumor necrosis factor (TNF) activity and bone marrow CFU-L were also detected. RESULTS: Before treatment, there was an inhibitory activity on CFU-Meg in the serum of APL patients (29.6% +/- 2.4%). The activity reduced gradually with the treatment and was stimulus when bone marrow remission obtained (-18.7% +/- 4.1%, P < 0.001). It was positively correlated with TNF activity in the serum and the number of CFU-L however negatively correlated with the number of megakaryocyte in bone marrow and PLT. Serum TNF activity and the number of CFU-L before treatment were higher than those after treatment (P < 0.05 and < 0.001, respectively). ATRA could stimulate the growth of CFU-Meg. CONCLUSIONS: There was an inhibitory activity in the serum of APL patients which could be used to monitor the efficacy of the therapy. ATRA stimulates the growth of CFU-Meg.

Adolescent↗
PubMed1996

Differential effects of warfarin on the intracellular processing of vitamin K-dependent proteins.

The vitamin K-dependent carboxylation of specific glutamyl residues to gamma-carboxyglutamyl residues occurs during the endoplasmic reticulum processing of a limited number of proteins. The fate of the under-gamma-carboxylated proteins during protein processing was studied. When human hepatoma (HepG2) cells were grown in the presence of warfarin, under-gamma-carboxylated prothrombin was secreted into the medium. In contrast, prothrombin secretion from a rat hepatoma (H-35) cell line was blocked by warfarin, and intracellular forms which were retained were degraded. When rat prothrombin (rFII) was stably transfected into warfarin treated HepG2 cells, endogenous human prothrombin (hFII) was secreted in an under-gamma-carboxylated form, while rFII accumulated intracellularly. These data indicate that retention and degradation of under-gamma-carboxylated prothrombin by human hepatocytes is related to a structural difference in rFII and hFII. When rFII and hFII were transfected into a warfarin treated transformed human embryonic kidney cell line (293), both proteins were secreted in an under-gamma-carboxylated form and intracellular retention was not observed. However, the secretion of rFII was greatly diminished. Cellular retention of under-gamma-carboxylated forms is therefore tissue specific, but degradation is not.

Animals↗
PubMed1996

[Clinical application of 72-hour fast expansion of the soft tissue].

The rapid expansion of the soft tissue has been applied in plastic surgery. To further shorten the expansion period, we undertook a clinical study on 72-hour fast expansion and applied this technique to 11 patients with different defects on their face, neck, shoulder or elbow after resection of scar, melanoma, angioma or due to trauma. Satisfactory results have gained. This paper not only introduces the clinical application of the technique, but also discusses the theoretical basis, advantages and key points of the operation.

Adolescent↗