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S F Liu

Publications and source records attributed to S F Liu.

At least 37 records · Page 2Linked to original sources
PubMed1998

Quantitative fluorescence image analysis of DNA content and nuclear morphology on esophageal balloon cytology smears and subsequent development of esophageal and gastric cardia cancer in Linxian, China.

The highest incidences of esophageal and gastric cardia cancer in the world occur in northern China. Chinese scientists have developed esophageal balloon cytology screening to detect these cancers, but traditional cytology is sometimes inadequate to find some early, curable lesions. Several studies suggest that quantitative fluorescence image analysis (QFIA) of DNA ploidy and nuclear morphology may be able to improve upon traditional cytology results. In October 1987, esophageal balloon cytology was performed on 1331 adults in Linxian, China, and all samples were evaluated both by traditional cytology and QFIA. From 1987 to May 1991, 62 new squamous esophageal cancers and 44 new adenocarcinomas of the cardia were identified in this cohort. Proportional hazards models were used to evaluate the relationship of cytological diagnoses and six QFIA variables to subsequent cancer risk. These models showed significant trends for increasing esophageal cancer risk, with increasing values in five of the QFIA variables and with increasing severity of the traditional cytological diagnoses. A comparison of models with only cytology variables versus models with both cytology and QFIA variables indicated that the QFIA provided an important additional predictive value. Persons with both cytological dysplasia and high cellular DNA were 8 times more likely to develop esophageal cancer than were individuals with neither of these conditions. For cardia cancer, associations between QFIA variables or cytological diagnoses and later cancer were more limited. This study suggests that the QFIA variables evaluated here are independent predictors of squamous esophageal cancer and that combining QFIA with traditional cytology can improve prediction of esophageal cancer risk.

Adenocarcinoma↗
PubMed1997

Cytologic detection of esophageal squamous cell carcinoma and precursor lesions using balloon and sponge samplers in asymptomatic adults in Linxian, China.

BACKGROUND: The principal reason for the poor prognosis of esophageal carcinoma is that most tumors are asymptomatic and go undetected until they are unresectable. Previous studies have shown that cytologic screening of asymptomatic high risk individuals can detect curable esophageal carcinomas and precursor lesions, but the sensitivity of such screening is not well documented. The current study evaluated the sensitivity and specificity of currently available balloon and sponge cytologic samplers for detecting biopsy-proven squamous dysplasia and carcinoma in asymptomatic individuals from a high risk population in Linxian, China. METHODS: Asymptomatic adults were examined with both balloon and sponge samplers, in random order, followed by endoscopy with mucosal iodine staining and biopsy of all unstained lesions. The cytology slides were interpreted using the criteria of the Bethesda System. The balloon and sponge cytologic diagnoses (test) were compared with the biopsy diagnosis (truth) in each patient to estimate the sensitivity and specificity of each sampler. RESULTS: Of the 439 patients with adequate biopsies, 123 (28%) had histologic squamous dysplasia and 16 (4%) had an invasive squamous carcinoma. The sensitivities/specificities of the balloon and sponge were 44%/99% and 18%/100%, respectively, for detecting biopsy-proven squamous cell carcinoma, and 47%/81% and 24%/92%, respectively, for identifying squamous dysplasia or carcinoma. CONCLUSIONS: In this study, the balloon sampler was more sensitive than the sponge sampler for detecting esophageal squamous disease, but both techniques were less than optimal. Improved samplers and/or cytologic criteria should increase the sensitivities observed in this baseline study.

Adult↗
PubMed1997

In vivo inhibition of nuclear factor-kappa B activation prevents inducible nitric oxide synthase expression and systemic hypotension in a rat model of septic shock.

We determined the in vivo function of LPS-induced nuclear factor-kappa B (NF-kappa B) activation in mediating inducible nitric oxide synthase (iNOS) mRNA and protein expression, and systemic arterial hypotension in a rat model of septic shock. LPS (8 mg/kg i.v.) challenge of rats activated NF-kappa B within 15 min in lung tissue, and the response persisted up to 4 h. NF-kappa B activation preceded the induction of iNOS mRNA. Pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-kappa B effective in cellular studies, prevented NF-kappa B activation in vivo and reduced iNOS mRNA expression and the increase in iNOS activity activated by LPS. At PDTC concentrations of 50, 100, and 200 mg/kg, the reductions of iNOS mRNA were 20, 46, and 48%, and the reductions in iNOS activity were 59, 66, and 75%, respectively. The PDTC concentration-dependent reductions in iNOS activity produced similar decreases in plasma nitrite/nitrate concentrations. PDTC also prevented the decrease in arterial blood pressure induced by LPS. These results demonstrate that activation of NF-kappa B is a critical in vivo regulatory mechanism mediating LPS-induced iNOS expression and the resultant systemic hypotension.

Animals↗
PubMed1997

Alternate COX-2 transcripts are differentially regulated: implications for post-transcriptional control.

Prostaglandin (PG) synthesis during inflammation occurs mainly via the transcriptionally regulated cyclooxygenase, COX-2. In pulmonary type II A549 cells, Northern analysis identified multiple IL-1 beta-inducible COX-2 mRNA transcripts. Amplification of 3'-cDNA ends by anchored PCR revealed products corresponding to the predominant 4.5 and 2.7 kb transcripts. Sequence analysis of amplification products indicated that these transcripts arose by alternate consensus and non-consensus polyadenylation site usage. The predominant 4.5 kb transcript showed a half-life in excess of two hours that was further stabilized by IL-1 beta. In addition, the COX-2 3'-untranslated region (UTR), which contains 22 copies of the putative RNA instability motif, AUUUA, when cloned downstream of a constitutively expressed luciferase gene, was found to confer partial IL-1 beta responsiveness in LA-4 cells. Finally, in vivo in LPS-treated rats, differential expression of similar COX-2 mRNA isoforms was also observed. Taken together these data suggest a functional role for post-transcriptional mechanisms, including alternate polyadenylation, in the control of COX-2.

Animals↗
PubMed1997

Inducible nitric oxide synthase after sensitization and allergen challenge of Brown Norway rat lung.

1. We studied the effects of ovalbumin (OA) sensitization and challenge on inducible nitric oxide synthase (iNOS) gene and protein expression in Brown-Norway rats in vivo. 2. By use of Northern analysis, a 4.4-kb iNOS mRNA transcript was weakly observed in control rat lung but there was a 3 fold increase in lungs sensitized to OA alone (P<0.05). In sensitized rats, four hours after exposure to OA aerosol, there was a 6 fold increase in iNOS mRNA transcript (P<0.05), which returned to baseline at 24 h. 3. Immunostaining with an anti-mouse iNOS antibody revealed some patchy staining of airway epithelium in naive rats. There were no changes in sensitized rats exposed to saline, but sensitized and OA-exposed rats showed increased expression in iNOS staining in macrophages. 4. Electrophoretic mobility shift assays of lung nuclear extracts showed a marked increase in nuclear factor-kappaB (NF-kappaB)-binding activity at 2 h after allergen exposure with return to baseline at 6, 12 and 24 h. 5. We concluded that there is increased iNOS gene and protein expression associated with increased NF-kappaB DNA-binding in lungs of sensitized and challenged rats. The increase in iNOS expression may underlie the increase in exhaled NO found after allergen challenge and may contribute to the development of allergen-induced airway hyperresponsiveness.

Allergens↗
PubMed1997

Time course and cellular localization of lipopolysaccharide-induced inducible nitric oxide synthase messenger RNA expression in the rat in vivo.

OBJECTIVES: The role of nitric oxide in mediating the early phase of hypotension and cardiovascular hyporeactivity in sepsis, and the cellular sources of inducible nitric oxide synthase expression under in vivo conditions, remain unclear. The objective of this study was to elucidate the time course and cellular location of inducible nitric oxide synthase messenger RNA (mRNA) expression in rats treated with lipopolysaccharide in vivo. DESIGN: Prospective, placebo-controlled, laboratory study. SETTING: Experimental laboratory of a postgraduate medical research institution. SUBJECTS: Normal, anesthetized rats. INTERVENTIONS: Animals were treated with lipopolysaccharide (15 mg/kg i.p.), saline (1 mL/kg i.p.), or lipopolysaccharide plus dexamethasone (3 mg/kg i.p., 50 mins before lipopolysaccharide administration) in vivo 4 hrs before the removal of tissues. MEASUREMENTS AND MAIN RESULTS: Total RNA and mRNA were extracted. Total RNA was used for reverse transcription polymerase chain reaction. Poly-(A)+ mRNA was isolated for Northern blot analysis. Cryostat sections of heart and lung were prepared for in situ hybridization to elucidate the cellular location of the inducible nitric oxide synthase gene. Hearts, lungs, aortae, and pulmonary arteries from lipopolysaccharide-treated animals expressed inducible nitric oxide synthase mRNA, which was markedly inhibited by pretreatment with dexamethasone (except in aorta). The threshold time point for inducible nitric oxide synthase mRNA induction was between 20 and 40 mins after lipopolysaccharide administration. The quantity of mRNA increased progressively thereafter, reaching a plateau between 4 and 8 hrs and decreasing markedly by 24 hrs. These findings are consistent with the time course of lipopolysaccharide-induced hypotension and cardiovascular hyporeactivity in animal models of septic shock and in man. Inducible nitric oxide synthase mRNA was mainly detected in vascular and airway smooth muscle cells, cardiac myocytes, pneumocytes, and infiltrated inflammatory cells, but was also identified in airway epithelial and vascular endothelial cells. Vascular smooth muscle represented the predominant cell type expressing inducible nitric oxide synthase under these conditions. CONCLUSIONS: These results provide further molecular evidence for the involvement of nitric oxide in the early phase of hypotension and cardiovascular hyporeactivity seen in septic shock. They also suggest that nitric oxide derived from vascular smooth muscle cells may contribute significantly to this hypotension and cardiovascular reactivity.

Animals↗
PubMed1997

Studies of esophageal balloon cytology in Linxian, China.

Esophageal cancer is the second leading cause of cancer death in China. Esophageal cancer has a very poor prognosis, principally because most tumors are asymptomatic until they are unresectable. Esophageal balloon cytology is an early detection method developed by Chinese scientists to identify resectable early cancers and precursor lesions. Previous studies have reported high sensitivities for detecting esophageal cancer in symptomatic patients. The current report describes several studies evaluating this diagnostic technique in asymptomatic individuals. A comparison of Chinese and U. S. cytological diagnoses of the same esophageal samples showed that the Chinese categories of precancerous neoplasia were more inclusive than the corresponding U. S. categories. Comparisons of both Chinese and U. S. cytological diagnoses with concurrent histological findings showed low (14-36%) sensitivities for the cytological detection of biopsy-proven cancers. Prospective follow-up studies of several screened cohorts showed a consistent progression of risk for developing esophageal cancer with increasing severity of initial cytological diagnosis. These preliminary studies suggest that esophageal balloon cytology is a useful technique that can benefit from additional research to improve its optimal performance.

Adult↗
PubMed1996

Differential regulation of cyclo-oxygenase-1 and cyclo-oxygenase-2 gene expression by lipopolysaccharide treatment in vivo in the rat.

1. Prostaglandins are important regulatory mediators of cardiovascular and pulmonary functions which may become disordered in patients with sepsis. The mechanisms controlling their synthesis and release under these circumstances remain unclear. Cyclo-oxygenase (COX, prostaglandin G/H synthase) is a key enzyme in prostaglandin synthesis and has two isoforms (COX-1 and COX-2). COX-1 is constitutively expressed and is probably responsible for prostaglandin release under physiological conditions, whereas COX-2 is expressed at high levels upon induction. 2. We investigated the effect of lipopolysaccharide treatment in vivo on differential COX-1 and COX-2 mRNA expression in the rat. 3. The 2.8 kb COX-1 message was detected in all lungs and seven hearts of eight control rats. In lipopolysaccharide-treated animals, COX-1 expression was reduced by approximately 5-fold in lungs and 2-fold in hearts as quantified by densitometry. In parallel, a marked upregulation of COX-2 mRNA expression was observed. The 4.4 kb COX-2 transcript was absent or expressed at low level in control lungs and hearts, but was increased by approximately 7- and 12-fold in lipopolysaccharide-treated lungs and hearts respectively. Neither the down-regulation of COX-1 nor the upregulation of COX-2 mRNA induced by lipopolysaccharide was significantly affected by pretreatment with dexamethasone in lung and heart, although expression of inducible nitric oxide synthase, induced by lipopolysaccharide, was markedly inhibited in the same tissues. 4. The down-regulation of COX-1 and upregulation of COX-2 may contribute to the multi-organ failure seen in sepsis.

Animals↗
PubMed1996

Differential regulation of the constitutive and inducible nitric oxide synthase mRNA by lipopolysaccharide treatment in vivo in the rat.

OBJECTIVE: Endotoxin and cytokines have been reported to have both stimulatory and inhibitory effects on endothelial cell-derived nitric oxide release. The discrepancy may be explained by differential regulation of the endothelial and inducible type of nitric oxide synthase gene expression. This study aimed to investigate the differential effect of lipopolysaccharide treatment in vivo on the three isoforms (endothelial, brain-type, and inducible) of nitric oxide synthase gene expression in the rat. DESIGN: Prospective, controlled, animal trial. SETTING: Experimental laboratory of a postgraduate medical research institution. SUBJECTS: Normal, anesthetized rats. INTERVENTIONS: Animals were treated with lipopolysaccharide (15 mg/kg iP), saline (1 mL/kg ip), or lipopolysaccharide plus dexamethasone (3 mg/kg ip, 50 mins before lipopolysaccharide administration) in vivo 4 hrs before experimentation. MEASUREMENTS AND MAIN RESULTS: The expression of endothelial, brain-type, and inducible nitric oxide synthase mRNAs was quantified by Northern blot analysis using bovine, rat, and mouse cDNA probes, respectively. An endothelial nitric oxide synthase mRNA was detected at 4.3 kilobase in the heart, lung, and aorta, and a 10-kilobase brain-type nitric oxide synthase mRNA was detected in the brain. The endothelial and brain-type signals were strong in tissues from animals treated with saline, but were reduced by three- to four-fold in tissues from lipopolysaccharide-treated rats as estimated by optical density ratio. The 4.4-kilobase inducible nitric oxide synthase mRNA detected using the murine cDNA probe was absent or negligible in the heart, lung, and brain from saline-treated rats, but was markedly increased in the same tissues from lipopolysaccharide-treated animals. Dexamethasone significantly inhibited lipopolysaccharide-induced inducible nitric oxide synthase mRNA expression, but had no effect on the down-regulation of endothelial and brain nitric oxide synthase mRNAs. CONCLUSIONS: Rats treated with lipopolysaccharide in vivo display down-regulation of endothelial nitric oxide mRNA in the heart, lung, and aorta, and brain-type nitric oxide synthase mRNA in the brain There was a parallel up-regulation of inducible nitric oxide synthase mRNA in all tissues except in the aorta. Dexamethasone prevents the induction of inducible nitric oxide synthase mRNA. but has no effect on the down-regulation of endothelial and brain-type nitric oxide synthase mRNAs induced by lipopolysaccharide. Thus, endotoxin regulates constitutive and inducible nitric oxide synthase mRNA differentially.

Animals↗
PubMed1995

Expression of inducible nitric oxide synthase mRNA in Brown Norway rats exposed to ozone: effect of dexamethasone.

We studied the effects of ozone exposure and dexamethasone on inducible nitric synthase (iNOS) gene expression in Brown Norway rats in vivo. Using a murine iNOS cDNA probe, we detected a 4.4 kb iNOS mRNA by Northern analysis in rat lung. The iNOS signal was weak in control lungs, but increased in lungs exposed to ozone (3 ppm, 6 h). Ozone-induced iNOS mRNA expression was time-dependent, with maximal expression at 2 h, declining by 8 h and increasing again at 24 h postexposure. Dexamethasone significantly reduced the iNOS mRNA expression in the lungs of both controls and ozone-exposed rats. These results demonstrate that ozone inhalation induces iNOS expression in vivo, thus providing evidence at the molecular level for the possible involvement of nitric oxide generation in ozone-induced pulmonary inflammation or lung damage.

Administration, Inhalation↗
PubMed1995

Pyopneumothorax associated with unsuspected endobronchial foreign body: a case report.

Chronic foreign body aspiration may cause a variety of complications. Nonspecific clinical presentations and chest radiographic manifestations often result in misdiagnosis or delayed diagnosis. We report an unusual complication of chronic foreign body aspiration--pyopneumothorax--in a 52-year-old patient presenting with productive cough and intermittent fever for more than 3 months. Obstructive pneumonia was highly suspected from the computed tomographic scan of the chest. Flexible fiberoptic bronchoscopy demonstrated a fish bone in the bronchial tree. The bone was successfully removed by forceps. Thoracotomy was done later to ensue adequate drainage of the pyopneumothorax. We report this case for ongoing education to increase the index of suspicion.

Bronchi↗
PubMed1994

Esophageal balloon cytology and subsequent risk of esophageal and gastric-cardia cancer in a high-risk Chinese population.

Linxian, China has some of the highest rates of esophageal/gastric cardia cancer in the world. In 1983, esophageal balloon cytology screening was performed in 3 communes in northern Linxian. Of the participants, 10,066 with no evidence of cancer were followed prospectively for 7 1/2 years to evaluate the ability of the initial cytologic diagnoses to identify individuals at increased risk for developing cancer of the esophagus or gastric cardia. A total of 747 incident cases of esophageal or cardia cancer and 322 deaths due to these tumors were identified during the follow-up period and used in this analysis. The risks for esophageal or cardia cancer incidence and mortality increased in parallel with the presumed severity of the 1983 Chinese cytologic diagnoses. After adjusting for potential confounding factors, relative risks for esophageal or cardia cancer incidence, by initial cytologic diagnosis, were normal = 1.00 (reference), hyperplasia = 1.25, dysplasia 1 = 2.20, dysplasia 2 = 4.22 and near-cancer = 5.96. Our results suggest that esophageal balloon cytology, as performed and interpreted in Linxian in 1983, successfully identified individuals at increased risk for developing cancer of the esophagus or gastric cardia.

Age Factors↗
PubMed1994

The effect of vitamin and mineral supplementation on esophageal cytology: results from the Linxian Dysplasia Trial.

The population of Linxian in China has one of the world's highest rates for esophageal/gastric cardia cancer, as well as documented nutritional deficiencies. To determine whether dietary supplementation with a multi-vitamin multi-mineral preparation could reduce the risk of esophageal cancer and favorably influence precursor lesions, 3,318 individuals age 40-69 with cytologically determined grade 1 or grade 2 esophageal dysplasia were randomly assigned to receive either an active multi-vitamin multi-mineral supplement or a placebo. Pills were distributed at monthly visits and incident cancers or deaths were recorded. At 30 and 72 months subsequent to randomization all living participants without a known incident cancer were asked to undergo repeat cytological examination of their esophagus. Based on these procedures participants were classified as having no dysplasia, dysplasia grade 1, dysplasia grade 2 or near cancer dysplasia. Diagnoses of cancer were based on the cytology findings plus available histologic, radiologic and clinical materials. At the end of the study there was little overall difference in cumulative risk of esophageal cancer between those receiving vitamin/mineral supplementation and those receiving placebo. There was, however, a significant increase in reversion to non-dysplastic cytology among the group receiving the active treatment. The odds of not having any dysplasia at the two post-randomization screens was 1.23 times higher in the active treatment group than in the placebo group. Within each treatment group higher categories of dysplasia were associated with higher rates of cancer.

Adult↗