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Biomedical subjects

N Li

Publications and source records attributed to N Li.

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

Direct inhibitory effects of taurine on norepinephrine-induced contraction in mesenteric artery of stroke-prone spontaneously hypertensive rats.

The effect of taurine on vascular reactivity was investigated in the mesenteric artery of Wistar Kyoto (WKY), and stroke-prone spontaneously hypertensive rats (SHRSP). Administration of taurine significantly decreased blood pressure of SHRSP but not WKY. The mesenteric artery of taurine-treated SHRSP was excised to observe the contractile responses to transmural electrical stimulation and to several vasoactive substances. Vasocontraction induced by norepinephrine (NE) was significantly decreased by taurine. However, contraction elicited by the other substances tested was not affected. Consistently, when the vessels of SHRSP were pretreated with taurine in vitro, only the NE-induced vasocontraction was specifically attenuated. No effect was observed in WKY vessels. These results indicate that the hypotensive effect of taurine is accounted for at least in part its direct action on blood vessels.

Analysis of Variance↗
PubMed1996

Pravastatin affects blood pressure and vascular reactivity.

To investigate the effect of endogenous cholesterol synthesis on blood pressure and vascular response, a HMG CoA reductase inhibitor, pravastatin (1 or 10 mg/kg per day) was administered orally for 2 or 4 weeks to spontaneously hypertensive rats (SHR/lzm) and normotensive Wistar-Kyoto (WKY/lzm) rats. Blood pressure was significantly increased in the pravastatin-treated groups of both strains, occurring in WKY after a longer treatment period than in SHR. The thoracic aortas from SHR and WKY were pretreated with pravastatin (10(-4)M). The vascular response to norepinephrine in terms of both contractility and sensitivity, was increased in the pravastatin-treated SHR aorta but not in the WKY aorta. The increased response was not observed in the presence of mevalonate. Acetylcholine-induced vascular relaxation in the aortas from both strains was not affected by pravastatin pretreatment. These results suggest that the vascular response to norepinephrine may be affected by the intracellular cholesterol synthesis pathway.

Animals↗
PubMed1996

Bedside prediction of mortality from bacteremic sepsis. A dynamic analysis of ICU patients.

The prognosis in patients with sepsis depends on severity of acute illness, underlying chronic diseases, and complications associated with infection. Adjusting for these factors is essential for evaluation of new therapies. The purpose of the present study was to determine variables readily identifiable at the bedside that predict mortality in intensive care unit (ICU) patients with sepsis and positive blood cultures. For a 5-yr period, all patients of a surgical ICU presenting with positive blood cultures and sepsis were systematically analyzed for clinical variables and organ dysfunctions at the day of onset of sepsis and bacteremia and during the subsequent clinical course. The prognostic value of these variables was determined using logistic regression procedures. Of the 5,457 admissions to the ICU, 176 patients developed sepsis with positive blood cultures (3.2 per 100 admissions). The fatality rate was 35% at 28 days after the onset of sepsis; in-hospital mortality was 43%. Independent predictors of mortality at onset of sepsis were previous antibiotic therapy (odds ratio [OR], 2.40; 95% confidence interval [CI95], 1.59 to 3.62; p = 0.034), hypothermia (OR, 1.43; CI95, 1.04 to 2.44; p = 0.030), requirement for mechanical ventilation (OR, 2.97; CI95, 1.96 to 4.51; p = 0.009), and onset-of-sepsis APACHE II score (OR, 1.21; CI95, 1.13 to 1.29; p < 0.001). Vital organ dysfunctions developing after the onset of sepsis influenced outcome markedly. The best two independent prognostic factors were the APACHE II score at the onset of sepsis (OR, 1.13 per unit; CI95, 1.08 to 1.17; p = 0.0016) and the number of organ dysfunctions developing thereafter (OR, 2.39; CI95, 2.02 to 2.82; p < 0.001). In ICU patients with sepsis and positive blood cultures, outcome can be predicted by the severity of illness at onset of sepsis and the number of vital organ dysfunctions developing subsequently. These variables are easily assessed at the bedside and should be included in the evaluation of new therapeutic strategies.

APACHE↗
PubMed1996

Cholecystokinin octapeptide reverses the inhibitory effect induced by electroacupuncture on C-fiber evoked discharges.

Extracellular single unit recordings were made from spinal dorsal horn wide dynamic range neurons in spinal transected, urethane-anesthetized rats. The unit discharges elicited by noxious electrical stimulation of the hind paw were suppressed by electroacupuncture (15 Hz, 0.3 ms, 3 mA, 30 min) placed at the hind leg points (S-36 and SP-6). Local spinal superfusion with naloxone (20 micrograms/15 microliters) or CCK-8 (10 ng/15 microliters) attenuated, whereas CCK-B receptor antagonist L365,260 (2.5 micrograms/15 microliters) enhanced the electroacupuncture effect. These findings provide further evidence for the notion that CCK-8, in the spinal cord, functions as an antiopioid substrate that antagonizes opioid- or electroacupuncture-induced analgesia.

Animals↗
PubMed1996

A seroepidemiologic study of Chlamydia pneumoniae, Chlamydia trachomatis and Chlamydia psittaci in different populations on the mainland of China.

To evaluate and compare the prevalence of antibodies to 3 chlamydial species in various populations on the mainland of China, the MIF test was used to detect both serum IgG and IgM antibodies to these species in the normal population (n = 711), in poultry workers (n = 51), in female prostitutes (n = 106), in patients attending the sexually transmitted diseases clinic (n = 98), and in adult patients with pneumonia and bronchitis (n = 108). In the normal population, IgG antibodies against C. pneumoniae, C. trachomatis and C. psittaci were present in 61.5%, 9.3%, and 3.5%, respectively, and increasing with age. Prevalence and geometric mean titers (GMT) of IgG antibodies to C. trachomatis in prostitutes (54.7%) and female (55%), but not male (15.4%) sexually transmitted disease patients were significantly higher than in the normal adult female population. The prevalence indicating both previous and recent C. psittaci infections in poultry workers was no higher than in the others. The prevalence of IgG antibodies and GMT to C. pneumoniae in patients with pneumonia and bronchitis was not statistically higher than in the normal adult population. Evidence of cross-reactivities in the MIF test between different species was found in both prevalence and GMT. Serum IgM antibodies were usually absent in patients who met the serological criteria of recent C. pneumoniae infection, indicating that most of them could be considered as reinfections. On the basis of our survey, acute antibodies to C. pneumoniae by the MIF test, if they are detected, may be valuable in the diagnosis of recent C. pneumoniae infections.

Adolescent↗
PubMed1996

[A clinical and pathological study of gliosarcoma].

In order to study the clinicopathological features, histogenesis and prognosis, 12 cases of gliosarcoma were reported representing 0.4% of a series of 2743 patients undergoing biopsy for CNS tumors. All the tumors originated from the cerebral hemispheres with a predilection for the temporal lobes. Half of the cases show more firm consistency and are rather well demarcated from brain tissue. Clinically, they are sometimes mistaken for meningiomas. Of the 10 patients with follow-up, 9 have died. The mean survival period after operation was 8 months, 1 cases is still alive and well for 3.2 years. There were some cases in which the origin of spindle cell populations could not be determined by H & E staining. Glioblastoma and malignant fibrous histiocytoma (MFH) element of the tumor was confirmed by electron microscopical examination and immunohistochemical stains for GFAP, Mac 387, VIM, FV III RA, etc. Osteosarcoma component in the tumor was detected in one case. It was accepted that MFH arose from the primitive uncommited mesenchyme.

Adult↗
PubMed1996

[Observations on signet cell invasion and metastasis in extra-mammary Paget's disease].

In order to evaluate the level of cell differentiation in extramammary Paget's disease (EMPD) and the relation with prognosis, the pathologic morphology of 20 EMPD cases were reviewed. We found two marked features of the invasive and metastatic Paget's cells: first, the Pagat cells were usually of signet ring shape; second, the cells formed gland-like structures. These features can be regarded as low differentiation and important risk factors for invasion and metastasis in EMPD.

Adult↗
PubMed1995

Synthesis, structure elucidation, and biochemical evaluation of 7 alpha- and 7 beta-arylaliphatic-substituted androst-4-ene-3,17-diones as inhibitors of aromatase.

The inhibition of aromatase, the cytochrome P450 enzyme complex responsible for the conversion of androgens to estrogens, may be useful for the endocrine treatment of breast cancer. Previously, several 7 alpha-thio-substituted androstenediones have been shown to be potent inhibitors of aromatase. Recent research has focused on producing a more metabolically stable aromatase inhibitor by replacing the carbon-sulfur bond at the 7 alpha-position with a carbon-carbon bond. The new inhibitors, 7 alpha-arylaliphatic-substituted androst-4-ene-3,17-diones (2-4), have alkyl chains of varying length between the steroid and the aryl ring at the 7 alpha-position. The desired targets were synthesized via a 1,6-conjugate addition of the appropriate cuprate to 17 beta-(tert-butyldimethylsiloxy)androsta-4,6-dien-3-one (7). The synthesis also resulted in the formation of the 7 beta-substituted diastereomers (10-11 and 13) as minor products. Initial assignments of the 7 alpha-phenethyl and 7 beta-phenethyl diastereomers were made using highfield 1-D and 2-D NMR studies. The assignment of the diastereomers was confirmed using X-ray crystallography. These compounds were all good inhibitors of aromatase in vitro when assayed using microsomes isolated from human placenta. The 7 alpha-substituted androst-4-ene-3,17-diones (2-4) were effective inhibitors with apparent Kis of 13-19 nM. The corresponding 17 beta-hydroxy analogs (8 and 14) and the 7 beta-substituted androstenediones (13 and 16) were less effective inhibitors with apparent Kis of 36-44 nM. Thus, a new series of 7 alpha-arylaliphatic-substituted androst-4-ene-3,17-diones has been synthesized, and the compounds are potent competitive inhibitors of aromatase.

Androstenedione↗
PubMed1995

Genomic structure of human transcobalamin II: comparison to human intrinsic factor and transcobalamin I.

Human transcobalamin II (TC II) gene was isolated and partially sequenced. The gene is composed of nine exons and eight introns spanning approximately 20 kb. Multiple potential transcription start sites were revealed by primer extension analysis. The 5'-flanking region of the gene contained no TATA-like motif, but a binding motif for HIP1, which is suggested to be important in the transcription of TATA-less housekeeping genes, was identified in a region very close to the initiator methionine codon. In addition, potential binding sites for a variety of transcription factors such as SP1, AP2, CF1, NF-IL6, Ets-1, Myb and E2A were also observed. Comparison of the genomic structure of TC II to other Cbl-binding proteins, human gastric intrinsic factor (IF) and transcobalamin I (TC I) revealed similar intron-exon organizations with respect to the number, position and size of exons. These results suggest that TC II, TC I and IF genes have originated by gene duplications of an ancestral gene and TC II, unlike the other two Cbl-binding proteins, is the product of a "housekeeping" gene.

Amino Acid Sequence↗
PubMed1995

Structure of uncomplexed and linoleate-bound Candida cylindracea cholesterol esterase.

BACKGROUND: Candida cylindracea cholesterol esterase (CE) reversibly hydrolyzes cholesteryl linoleate and oleate. CE belongs to the same alpha/beta hydrolase superfamily as triacylglycerol acyl hydrolases and cholinesterases. Other members of the family that have been studied by X-ray crystallography include Torpedo californica acetylcholinesterase, Geotrichum candidum lipase and Candida rugosa lipase. CE is homologous to C. rugosa lipase 1, a triacylglycerol acyl hydrolase, with which it shares 89% sequence identity. The present study explores the details of dimer formation of CE and the basis for its substrate specificity. RESULTS: The structures of uncomplexed and linoleate-bound CE determined at 1.9 A and 2.0 A resolution, respectively, reveal a dimeric association of monomers in which two active-site gorges face each other, shielding hydrophobic surfaces from the aqueous environment. The fatty-acid chain is buried in a deep hydrophobic pocket near the active site. The positioning of the cholesteryl moiety of the substrate is equivocal, but could be modeled in the hydrophobic core of the dimer interface. CONCLUSIONS: The monomer structure is the same in both the complexed and uncomplexed crystal forms. The dimers differ in the relative positions of the two monomers at the dimer interface. Of the 55 residues that are different in CE from those in C. rugosa lipase 1, 23 are located in the active site and at the dimer interface. The altered substrate specificity is a direct consequence of these substitutions.

Animals↗
PubMed1995

High sex ratios in China's future.

In China in recent years, male live births have exceeded those of females by amounts far greater than those that occur naturally in human populations, a trend with significant demographic consequences. The resulting imbalance in the first-marriage market is estimated to be about 1 million males per year after 2010. These "excess" males were not easily accommodated in models with substantial changes in first-marriage patterns. The current sex ratio at birth has little effect on a couple's probability of having at least one son, so future increases in the sex ratio may well occur, especially given increasing access to sex-selective abortion.

China↗
PubMed1995

Systemic inflammatory response syndrome, sepsis, severe sepsis and septic shock: incidence, morbidities and outcomes in surgical ICU patients.

OBJECTIVES: To determine the incidence of systemic inflammatory response syndrome (SIRS), sepsis and severe sepsis in surgical ICU patients and define patient characteristics associated with their acquisition and outcome. DESIGN: One-month prospective study of critically ill patients with a 28 day in-hospital follow up. SETTING: Surgical intensive care unit (SICU) at a tertiary care institution. METHODS: All patients (n = 170) admitted to the SICU between April 1 and April 30, 1992 were prospectively followed for 28 days. Daily surveillance was performed by two dedicated, specifically-trained research nurses. Medical and nursing chart reviews were performed, and follow up information at six and twelve months was obtained. RESULTS: The in-hospital surveillance represented 2246 patient-days, including 658 ICU patient-days. Overall, 158 patients (93%) had SIRS for an incidence of 542 episodes/1000 patients-days. The incidence of SIRS in the ICU was even higher (840 episodes/1000 patients-days). A total of 83 patients (49%) had sepsis; among them 28 developed severe sepsis. Importantly, 13 patients had severe sepsis after discharge from the ICU. Patient groups were comparable with respect to age, sex ratio, and type of surgery performed. Apache II score on admission to the ICU and ASA score at time of surgery were significantly higher (p < 0.05) only for patients who subsequently developed severe sepsis. The crude mortality at 28 days was 8.2% (14/170); it markedly differed among patient groups: 6% for those with SIRS vs. 35% for patients with severe sepsis. Patients with sepsis and severe sepsis had a longer mean length of ICU stay (2.1 +/- 0.2 and 7.5 +/- 1.5, respectively) than those with SIRS (1.45 +/- 0.1) or control patients (1.16 +/- 0.1). Total length of hospital stay also markedly differed among groups (35 +/- 9 (severe sepsis), 24 +/- 2 (sepsis), 11 +/- 0.8 (SIRS), and 9 +/- 0.1 (controls, respectively). CONCLUSIONS: Almost everyone in the SICU had SIRS. Therefore, because of its poor specificity, SIRS was not helpful predicting severe sepsis and septic shock. Patients who developed sepsis or severe sepsis had higher crude mortality and length of stay than those who did not. Studies designed to identify those who develop complications of SIRS would be very useful.

Critical Care↗
PubMed1995

Antioxidant enzyme levels as a function of growth state in cell culture.

Manganese superoxide dismutase (MnSOD) levels were monitored as a function of time in culture to determine whether these levels were altered at logarithmic growth versus when the cells exhibited density limitation of growth. For comparison, activities of the antioxidant enzymes copper, zinc superoxide dismutase (CuZnSOD), catalase, and glutathione peroxidase were also evaluated. Four cell lines were studied, two of which exhibited density limitation of growth and two of which did not. Each cell line showed a unique antioxidant enzyme profile. The two cell lines that showed density limitation of growth also demonstrated induction of MnSOD at the time when the cells stopped proliferating in culture, whereas the other two cell lines did not show induction of MnSOD. There was no strict correlation between density limitation of growth and activities of the other antioxidant enzymes. To determine whether SOD varied with various phases of the cell cycle, NIH/3T3 cells were synchronized using serum starvation, and then SOD activities were measured during quiescence (G0) and the phase of DNA synthesis (S-phase). MnSOD was decreased during S-phase compared with G0, whereas CuZnSOD was increased during S-phase compared with G0, demonstrating alteration of SOD activities with varying phases of the cell cycle. This study suggests the possibility that increased MnSOD may correlate with decreased cell proliferation and suggests significant alterations in SOD activities during the cell cycle.

3T3 Cells↗
PubMed1995

HMG-CoA reductase inhibitor affects blood pressure and vascular reactivity.

1. To investigate the effect of endogenous cholesterol synthesis on blood pressure and vascular response, a HMG CoA reductase inhibitor, pravastatin (1 or 10 mg/kg) was administered orally for 2 or 4 weeks to 8-13 week old spontaneously hypertensive rats (SHR/Izm) and normotensive Wistar-Kyoto (WKY/Izm) rats. 2. Blood pressure was significantly increased in the pravastatin-treated groups of both strains, but the elevation was observed in WKY after a longer treatment than in SHR. 3. After the thoracic aorta from 10-12 week old SHR and WKY was pretreated with pravastatin (10(-4) mol/L), the vascular response to norepinephrine was increased in pravastatin-treated SHR aorta but not in the WKY aorta in both contractivity and sensitivity. 4. These experiments suggest that the vascular response is affected by intracellular cholesterol synthesis pathway.

Animals↗
PubMed1995

[The value of serum myelin basic protein in assessment of severity of acute closed head trauma].

Serum levels of myelin basic protein (MBP) were measured in 112 patients after acute head injury by enzyme linked immuno-absorbent assay (ELISA). Patients with cerebral concussion showed no significant change in serum MBP. Patients with cerebral contusion, extradural hematoma or intracerebral hematoma had a mean serum MBP concentration much higher than that of patients with cerebral concussion. And patients with extradural hematoma had a mean serum MBP concentration much lower than that of patients with cerebral contusion and intracerebral hematoma; the differences were significant (P < 0.05). But there was no significant difference between patients with cerebral contusion and intracerebral hematoma (P > 0.05). The amount of serum MBP was significantly correlated with the volume of extradural hematoma, intracerebral hematoma and with the extent of the cerebral contusion (P < 0.05). This study suggested that the serum MBP may reflect the type and severity of closed head injury patients.

Adolescent↗
PubMed1995

Absorptive function of segmental allotransplanted small intestines in pigs.

Ten outbred pigs were each operated on for three times. First, a 130 cm length of terminal ileum of each pig was isolated on its vascular pedicle as a Thirty-Vella loop. One week later, the solitary ileal segments were transplanted heterotopically in two pigs. And after 28 days of heterotopic transplantation, the transplanted intestine was interposed into continuity of host intestine as orthotopic transplant. During the experiment, tests were made on 6th day after the first operation (period I), the 14th (II), 28th (III) day after heterotopic transplantation, and 3 weeks after interposition (IV) respectively for the levels of glucose, palmitate and leucine. Additionally, at period I, III, and IV, a 3 cm length of intestinal mucosa was excised for morphologic observation and determination of DNA, RNA and protein contents. After heterotopic transplantation, the absorptive function of transplanted intestine was severely impaired for two weeks. The absorption of glucose and palmitate was partially recovered by period III, at which time leucine level had return to normal. At period IV, the absorptive function of glucose and leucine had surpassed normal levels, while palmitate had risen to the level of pretransplantation. After transplantation, at period III, DNA, RNA and protein contents were well below normal. Three weeks after orthotopic transplantation, RNA and protein had risen to normal level, while DNA content remained below normal. The morphologic changes during the experiment were correlated with the changes of contents in RNA, protein and DNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[Experimental and clinical studies of small bowel allotransplantation].

The pigs with allograft were divided into 5 groups according to the different immunosuppressive regimens. Acute rejection of allograft occurred in animals not treated with immunosuppressive agents or treated with low dose of cyclosporine (CsA). There was no rejection developed in the pigs treated with high dose CsA or low dose CsA and tripterygium wilfordii (TW). No evidence of chronic rejection was detected in animals with continued administration of TW after living longer than 100 days when the immunosuppressive treatment was discontinued. A woman with enterocolitis, ileus and short-gut syndrome received a complete cadaveric small bowel transplantation in march 12, 1994. The graft had 6 minutes for warm ischemia and 9 hours and 45 minutes for cold ischemia. The immunosuppressive therapy consisted of CsA, TW and methylprednisolone. The patient is alive and the function of graft is normal.

Adult↗