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Biomedical subjects

W Liu

Publications and source records attributed to W Liu.

At least 775 records · Page 43Linked to original sources
PubMed1996

The continuing increase in adenocarcinoma of the uterine cervix: a birth cohort phenomenon.

BACKGROUND: Adenocarcinoma of the uterine cervix has been reported to be increasing among young white women and earlier studies suggest a birth cohort pattern for the observed increase. No study, however, has examined the time trends of adenocarcinoma of the cervix by birth cohort. METHODS: Using Surveillance, Epidemiology, and End Results (SEER) data through 1990, the current study is designed to examine the time trends of invasive adenocarcinoma by birth cohort. An age-period-cohort model was fitted to the annual-age-specific rates to identify the components of birth cohort and time period as determinants of the observed time trends. RESULTS: The results from this study clearly show that invasive adenocarcinoma of the uterine cervix has been increasing in both whites and blacks, but the increase is statistically significant only among whites, reaching 4.2 percent per year for those born since 1935. The results also show that the recent increase in invasive adenocarcinoma started among those born around the mid 1920s, and a strong birth cohort effect is largely responsible for the observed increase. CONCLUSION: Invasive adenocarcinoma of the uterine cervix is increasing among recent birth cohorts. Analytical epidemiological studies are urgently needed to explore the risk factors responsible for the increase. The time trends for adenocarcinoma of the cervix should also be carefully monitored in the coming years.

Adenocarcinoma↗
PubMed1996

Characterization of cauliflower mosaic virus (CaMV) resistance in virus-resistant ecotypes of Arabidopsis.

Two Arabidopsis ecotypes are resistant to systemic infection by cauliflower mosaic virus (CaMV), a plant para-retrovirus. Arabidopsis ecotype Enkheim-2 (En-2) is highly resistant to CaMV infection while Bla-14 is more weakly resistant. CaMV resistance in En-2 can be largely attributed to the action of a single semidominant gene called cauliflower mosaic virus resistance1 (CAR1), located at a locus on chromosome 1. Resistance in Bla-14 is tightly linked to CAR1 and may be due to a weak allele at the same locus or another gene in a gene cluster. A quantitative polymerase chain reaction assay in conjunction with replication- and movement-incompetent viral mutants was used to determine whether virus replication or movement is affected in the resistant ecotypes. The pattern of accumulation of the wild-type virus in the resistant ecotype, En-2, was similar to that of a movement-incompetent CaMV mutant, suggesting that CAR1 interferes with or fails to support CaMV movement. CaMV-inoculated En-2 plants do not show visible signs of a hypersensitive response. However, indicators of an induced defense response do appear in CaMV-infected En-2 plants, such as the activation of pathogenesis-related protein gene expression and the production of camalexin, an Arabidopsis phytoalexin. Defense responses induced chemically or by mutation in the susceptible ecotypes delayed and reduced the severity of a CaMV infection. These findings suggest that CAR1 acts either in the susceptible ecotype to support virus movement or in the resistant ecotype to signal a defense response.

Arabidopsis↗
PubMed1996

Characterization of the sympathetic nerve responses to amphetamine: role of central alpha 2-adrenergic receptors.

Although amphetamine has profound cardiovascular actions, the role of the sympathetic nervous system in these responses is largely unknown. The purpose of this study was to characterize the sympathetic nerve responses to amphetamine and to determine whether these neural responses involve an action of amphetamine in the rostral ventrolateral medulla (RVLM). In sinoaortically denervated (SAD) and sham-SAD rats, amphetamine dose-dependently increased mean arterial pressure (MAP) and heart rate (HR), while decreasing (-87 +/- 5%, max) renal sympathetic nerve discharge (SND) for 57 +/- 5 min. Comparison of the SND responses in SAD and sham-SAD rats revealed a small but significant contribution of the baroreceptor reflex to the sympathoinhibitory response. In separate studies, the bilateral microinjection of amphetamine into RVLM decreased HR, MAP, and SND. The magnitude and duration of the decrease in SND elicited by amphetamine were significantly attenuated by the prior intravenous (i.v.) administration of idazoxan (alpha 2-adrenergic antagonist). The prior bilateral microinjection of idazoxan or piperoxan into RVLM significantly attenuated the duration of the sympathoinhibitory responses elicited by i.v. amphetamine. Idazoxan and piperoxan also tended to decrease the magnitude of the SND response; however, this reduction was significant at only the highest doses. The MAP and HR responses were unaffected by idazoxan treatment. The microinjection of terazosin (alpha 1-adrenergic antagonist) or propranolol (beta-adrenergic antagonist) into RVLM did not alter the HR, MAP, or SND responses to i.v. amphetamine. We conclude that i.v. amphetamine decreases SND in anesthetized rats, in large part, by a mechanism involving the activation of alpha 2-adrenergic receptors in RVLM.

Adrenergic Agents↗
PubMed1996

Promoter elements that mediate the pH response of PCK mRNA in LLC-PK1-F+ cells.

The onset of metabolic acidosis causes an increased transcription of the renal phosphoenolpyruvate carboxykinase (PCK) gene. When transgenic mice carrying a bovine growth hormone (bGH) gene driven by the -460 to +73 segment of the PCK promoter were made chronically acidotic, the bGH mRNA was increased twofold after 4 days. Confluent and well-differentiated cultures of LLC-PK1-F+ cells exhibit a 2.5-fold increase in PCK mRNA when transferred to acidic media (pH 6.9, 10 mM HCO3-) for 16 h. Confluent cultures transfected with PCK-490 CAT exhibit an increase (3.5-fold) in chloramphenicol acetyltransferase (CAT) activity when shifted to acidic medium for 48 h. Mutation or deletion of the P2 element causes a four- to fivefold decrease in basal CAT activity but does not affect the pH response. In contrast, mutations of the P3(II) element or the CRE-1 cAMP-response element have little effect on basal activity but cause a 50% decrease in the pH response. Other deletions or mutations have little effect on either activity. Thus changes in the activity or levels of the protein(s) in the renal proximal tubule that binds to the P3(II) and CRE-1 elements may mediate increased transcription of the PCK gene during metabolic acidosis.

Animals↗
PubMed1996

Artificial neural network to assist psychiatric diagnosis.

BACKGROUND: Artificial Neural Network (ANN), as a potential powerful classifier, was explored to assist psychiatric diagnosis of the Composite International Diagnostic Interview (CIDI). METHOD: Both Back-Propagation (BP) and Kohonen networks were developed to fit psychiatric diagnosis and programmed (using 60 cases) to classify neurosis, schizophrenia and normal people. The programmed networks were cross-tested using another 222 cases. All subjects were randomly selected from two mental hospitals in Beijing. RESULTS: Compared to ICD-10 diagnosis by psychiatrists, the overall kappa of BP network was 0.94 and that of Kohonen was 0.88 (both P < 0.01). In classifying patients who were difficult to diagnose, the kappa of BP was 0.69 (P < 0.01). ANN-assisted CIDI was compared with expert system assisted CIDI (kappa = 0.72-0.76); ANN was more powerful than a traditional expert system. CONCLUSION: ANN might be used to improve psychiatric diagnosis.

Adult↗
PubMed1996

Steroid receptor transcriptional synergy is potentiated by disruption of the DNA-binding domain dimer interface.

The dimer interface within the DNA-binding domain (DBD) of the steroid receptors stabilizes receptor binding to a palindromic DNA site termed a hormone response element (HRE) and is essential for receptor transcriptional activity when a single HRE drives transcription of a target gene. However, most steroid-responsive genes are driven by multiple HREs, and synergy between HREs is an important determinant of receptor activity. We have examined the effects of mutations within the DBD dimer interface on synergistic transcriptional activation by the mineralocorticoid and glucocorticoid receptors. As expected, mutations in either the mineralocorticoid receptor or glucocorticoid receptor that destabilized the DBD dimer interface disrupted receptor binding and activity at a single HRE. However, in striking contrast, these same mutations markedly increased receptor synergistic activity on a reporter gene containing multiple HREs and modestly increased DNA binding. Reestablishing intersubunit contacts by compensatory mutation or by coexpression of complementary mutants returned activity to near-wild type levels. These observations strongly suggest that the DBD dimer interface restrains steroid receptor transcriptional synergy and may play an unexpected role in the regulation of receptor activity.

Amino Acid Sequence↗
PubMed1996

[The diagnoses and treatment of traumatic retinal detachment].

PURPOSE: The diagnoses and treatments of traumatic retinal detachment (RD) were studied retrospectively in this article. METHODS: A sequence of 25 eyes of traumatic RD included 12 eyes of contusion, 4 explosion and 9 perforation; PVR (Proliferative vitreoretinopathy) < or = C grade 16 eyes and D grade 9 eyes. The techniques were, one: scleral cryotherapy, silicon band buckling and circling, external drainage, which was mainly used to PVR < or = C cases; two: vitrectomy and silicon oil tamponade, which was mainly used to the cases of perforated PVR-D cases. RESULTS: Retinal reattachment rate was 91.67% in technique one and 69.23% in technique two. Improvement of visual acuity showed that partial RD was better than total RD (P < 0.01), PVR < or = C better than PVR-D (P < 0.05) and non-perforated better than perforated (P < 0.05). CONCLUSION: The patient who had a history and visual symptoms after an eye injury must be carefully examined by dilating pupil in order that the RD could be early inquired and treated. The techniques one and two must be performed in the severe perforated cases.

Adolescent↗
PubMed1996

Selective arterial embolization in the management of internal bleeding caused by trophoblastic diseases.

OBJECTIVE: To evaluate the efficacy and safety of selective arterial embolization in the management of internal bleeding caused by trophoblastic diseases. PATIENTS AND METHODS: Four patients with internal bleeding caused by trophoblastic diseases were diagnosed with arteriography and treated with selective arterial embolization as a life-saving measure. Effect of controlling bleeding was assessed by follow-up arteriogram and clinical observation. RESULTS: The embolization successfully controlled the bleeding in all patients. Operation time was short with a mean of 42 minutes. The shock was corrected dramatically. Fever and pain were common complications. CONCLUSION: Selective arterial embolization is a life-saving measure in the management of internal bleeding caused by trophoblastic diseases.

Adult↗
PubMed1996

Histological and electron-microscopic observations on the mucosa of pediculate gastric wall graft transplanted to the intestines in Wistar rats.

OBJECTIVE: To study the machanism of the development of intestinal metaplasia through the transplantation of a flap of gastric wall with vascular pedicle to the intestines. METHODS: The pedicled gastric wall flaps of Wistar rats were transplanted to their duodenum, jejunum and colon respectively. After the operation the rats were killed at the 3th, 6th, 9th and 12th month respectively, and histological change of the gastric grafts was observed with optical and electron microscopy. RESULTS: Intestinal metaplasia was found in all the gastric grafts transplanted to the intestines and the alkaline phosphatase positive intestinal metaplasia was seen in the gastric graft mucosa transplanted to the duodenum and jejunum. CONCLUSIONS: The formation of intestinal metaplasia in the gastric mucosa may be related to a change of the microenvironment around the tissues, and gastric mucosa may differentiate into intestinal mucosa by the increase of pH value. The possible mechanism of the development of intestinal metaplasia was discussed.

Anastomosis, Surgical↗
PubMed1996

[Pathological observation and immunohistochemistry study of Type I, III, IV collagen in mitral valve and cardiac interstitium of rheumatic disease].

OBJECTIVES: To examine the pathological base of mitral valve and cardiac interstitium of rheumatic disease, and to explore the relationship between Type I, and III, IV collagen in mitral and cardiac interstitium of rheumatic heart disease. METHODS: HE and ABC method special staining were used to observe the mitral valve and cardiac interstitium pathology in 26 case. RESULTS: Diffused collagen fibroplasia, hyaline and amyloid degeneration were noted and sometimes associated local necrosis and calcification in myocardial interstitium and in mitral valve. It was a significant pathologic characteristic of rheumatic heart disease. The localization of Type I, III and IV collagen in the valve and myocardiac tissues was studied by ABC method of immunohistochemistry. Significant fibroplasia of collagen Type I and III was found in the valve, cordae tendon and myocardial interstitium of rheumatic heart disease. The composition and secretion of collagen Type I and III were expressed not only in fibroblasts but also in myocardial cells. CONCLUSIONS: The pathologic foundation of valve and myocardial fibrosis is collagen fibroplasia. The degree of fibroplasia is related to the repeated reaction of chronic rheumatic inflammation.

Adult↗
PubMed1996

Increased expression of cyclin D1 in a murine mammary epithelial cell line induces p27kip1, inhibits growth, and enhances apoptosis.

Cyclin D1 is frequently amplified and/or overexpressed in human breast cancer and several other types of cancer. To examine the role of cyclin D1 in normal mammary epithelial cells, in the present study we have overexpressed human cyclin D1 in the mouse mammary epithelial cell line HC11, using retrovirus-mediated transduction. We found that the cyclin D1 overexpresser clones displayed a decrease in saturation density, a decrease in anchorage-independent growth, an increased fraction of cells in the G(zero)-G1 phase, and increased expression of beta-casein, when compared to the control cells. The latter finding suggested that they were more differentiated. Furthermore, the cyclin D1 overexpressers displayed a marked increase in susceptibility to induction of apoptosis by serum withdrawal or by treatment with hydroxyurea or the protein kinase C inhibitors CGP 41251 and Ro31-8220. Thus, in some mammary epithelial cells, increased expression of cyclin D1 can inhibit growth, induce differentiation, and enhance apoptosis. These effects might be due, at least in part, to the fact that these derivatives displayed increased expression of the p27kip1 inhibitory protein.

Animals↗
PubMed1996

The role of the neurotrophins in maturation and maintenance of postnatal auditory innervation.

Auditory hair cells produce trophic factors that directly affect maturation and survival of auditory neurons. These factors include two members of the neurotrophin family: brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3). Loss of hair cells, as a result of either noise trauma or ototoxic damage, results in the degeneration of auditory neurons. An in vitro model of early postnatal rat organ of Corti/spiral ganglion explants was used to study the effects of deprivation and supplementation of nerve growth factor (NGF), BDNF, and NT-3 on neuronal survival. Immunolocalization of receptors for these neurotrophins correlated with their effectiveness as promoters of neuronal survival. BDNF affected early neuronal survival, whereas NT-3 was the most important survival factor for maturing auditory neurons. NGF was shown to maintain axonal morphology. Our results support the hypothesis that changes in the expression of these neurotrophins and their specific receptors in the maturing cochlea may control the postnatal processes of neuronal apoptosis and maturation of the innervation of both inner and outer hair cells. The results suggest that these growth factors have potential for preventing neuronal degeneration as well as enhancing the repair of damaged neuronal processes in the traumatized auditory system.

Animals↗
PubMed1996

YAC cloning and identification of rice (Oriza sativa L.) genomic DNA.

Construction of the genomic library by using yeast artificial chromosomes (YAC) has been an approach to a map-based gene cloning strategy. We have obtained more than 2000 YAC clones for the construction of a rice (Oriza sativa L.) genomic library through a procedure that could be summarized as follows: a fractionate by the pulsed-field gel electrophoresis (PFGE), the rice nucleic high molecular weight (HMW) DNA which is partially digested with EcoRI, and recovered fragments larger than 200 kb; ligate the fragments to the EcoRI digested YAC vector pairs pJS97 and pJS98; transform competent spheroplasts prepared from yeast strain YPH252; and select transformants directly on Ura-Trp-double selective media. Southern hybridization results indicated that the sizes of inserts were in the range of 200-820 kb.

Chromosomes, Artificial, Yeast↗
PubMed1996

Blockade of alpha-2 adrenergic receptors in the rostral ventrolateral medulla attenuates the sympathoinhibitory response to cocaine.

The purpose of this study was to determine whether neurons in the rostral ventrolateral medulla play a role in the sympathoinhibitory response elicited by i.v. administration of cocaine and, if so, to identify the type(s) of receptors involved. Adrenergic antagonists were microinjected bilaterally into the rostral ventrolateral medulla in pentobarbital-anesthetized rats in an attempt to block the decrease in sympathetic nerve discharge (SND) elicited by cocaine (1 mg/kg i.v.). After the bilateral microinjection of saline, cocaine elicited a -56 +/- 5% (mean +/- S.E.) decrease in SND lasting 36 +/- 3 min. Cocaine also increased arterial pressure (21 +/- 3 mm Hg). Prior microinjection of the alpha-2 adrenergic antagonist idazoxan (0.3, 3 or 10 nmol) did not alter the magnitude of the sympathoinhibitory response to cocaine; however, the duration of the response was significantly reduced by all 3 doses (range 21 +/- 3 to 11 +/- 2 min). Similarly, microinjection of the alpha-2 adrenergic antagonist piperoxan (10 nmol) decreased the duration (from 45 +/- 8 to 23 +/- 4 min), but not the magnitude of the sympathoinhibitory response. Microinjection of either the alpha-1 adrenergic antagonist terazosin (0.24 nmol) or the beta adrenergic receptor antagonist propranolol (2 nmol) did not attenuate the decrease in SND elicited by cocaine. The cocaine-mediated pressor response was not affected by any of the antagonist treatments. These data show that the decrease in SND elicited by cocaine is mediated centrally and involves, at least in part, the activation of alpha-2 adrenergic receptors in the rostral ventrolateral medulla.

Adrenergic alpha-2 Receptor Antagonists↗