Search PubMed⌕ Search

Biomedical subjects

J Stein

Publications and source records attributed to J Stein.

At least 91 records · Page 5Linked to original sources
PubMed2001

Butyrate and the cytokine-induced alpha1-proteinase inhibitor release in intestinal epithelial cells.

BACKGROUND: Alpha1-proteinase inhibitor (alpha1-PI), an anti-inflammatory protein thought to play a role in the intestinal inflammation, is synthesised by and released from the intestinal epithelial cells. IL-1beta is a key proinflammatory cytokine in the abnormal immune response that occurs in inflammatory bowel disease. Butyrate is a normal luminal constituent in the colon, known to be of benefit in preventing inflammatory bowel disease. Direct modes of action of butyrate in intestinal inflammation have been poorly studied so far. The aim of this study was to investigate the effects of butyrate on cytokine-mediated alpha1-PI release in intestinal epithelial cells. METHODS: Differentiated Caco-2 cells were incubated with IL-1beta in the presence or absence of 2 mM butyrate. Alpha1-PI expression in the cells was evaluated by Western blot analysis and alpha1-PI release by ELISA. RESULTS: Treatment with butyrate alone had no effect on alpha1-PI expression in differentiated Caco-2 cells. However, treatment of the cells with 2 mM butyrate significantly reduced the alpha1-PI level in IL-1beta-treated cells. In the cell culture medium, the presence of butyrate impaired the IL-1beta-induced alpha1-PI release to 17-35%. The treatment induced no change in the number of detached cells or the percentage of viable cells. CONCLUSION: Our data show that butyrate inhibits alpha1-PI release from Caco-2 colonocytes treated with IL-1beta. It is therefore likely that anti-inflammatory actions of butyrate occur via a mechanism that does not involve direct regulation of cytokine-induced anti-inflammatory protein expression in intestinal epithelial cells.

Butyrates↗
PubMed2001

Determination of alpha1-proteinase inhibitor by a new enzyme linked immunosorbant assay in feces, serum and an enterocyte-like cell line.

Although alpha(1)-proteinase inhibitor (alpha(1)-PI), the main serine proteinase inhibitor in human plasma, is predominantly liver-derived, the proof of fecal alpha(1)-PI is a maker for intestinal protein loss. Furthermore, alpha(1)-PI is synthesized locally by human intestinal epithelial cell lines (e. g. Caco-2). Therefore, we investigated the diagnostic value of a new enzyme-linked immunosorbent assay (ELISA) to detect alpha(1)-PI in serum, feces, and Caco-2 supernatants in comparison with radial immunodiffusion (RID). alpha(1)-PI concentrations assessed by ELISA were on an average 30 % higher than those measured by RID. Only the ELISA system detected alpha(1)-PI in supernatants of Caco-2 cells. Our data imply first that this ELISA system is more sensitive to assess alpha(1)-PI than other methods, and second that it obviously determines locally synthesized alpha(1)-PI which can not be liver-derived. However, further examinations are necessary to distinguish between enterocyte-derived or systemic alpha(1)-PI and its diagnostic relevance in bowel disease.

Adolescent↗
PubMed2001

Colonic fermentation as affected by antibiotics and acidic pH: Application of an in vitro model.

Antimicrobial substances such as vancomycin or metronidazole suppress normal gut flora, thereby preventing physiological fermentation of colonic substrates that may promote mucosal inflammation. This study was designed to establish an in vitro model of microbial metabolism in the colon under control and disturbed conditions (acidic pH) to investigate specific effects of vancomycin and metronidazole on the production of short chain fatty acids (SCFA), which play a pivotal role in maintaining homeostasis in the colon. The experiments were carried out with the colon simulation technique (Cositec) representing an in vitro model for the semi-continuous incubation of defined colon contents. Inocula and fermentable substrates were sampled from cecal contents of fistulated pigs. Disturbed microbial metabolism was generated by reduction of pH in the fermentation vessels from 6.7 to 5.8 and 5.1. In general, application of either vancomycin or metronidazole resulted in a significant decrease of SCFA production rates indicating substantial disturbance of the homeostasis of microbial metabolism. With low doses of vancomycin acetate and butyrate production rates were reduced and with high doses of the antibiotic propionate production was inhibited to a greater extent. Treatment with metronidazole inhibited butyrate production almost completely. Similarly, low pH caused a reduction in total SCFA production, which was mainly due to respective decrease of acetate synthesis. Metronidazole effects were not consistently changed at low pH. The Cositec system provides an excellent facility to test the effects of different antibiotics under defined conditions. In this study, both vancomycin and metronidazole affected microbial metabolism to a considerable extent. Both substances may thus be responsible for disturbances of colon function in vivo.

Acid-Base Equilibrium↗
PubMed2001

HMG-CoA reductase inhibitor mevastatin enhances the growth inhibitory effect of butyrate in the colorectal carcinoma cell line Caco-2.

Mevastatin is an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme in cholesterol synthesis. Butyrate, a short-chain fatty acid, reduces proliferation and induces differentiation of human colon cancer cells. The aim of our study was to determine the effect of mevastatin, alone or in combination with butyrate, on proliferation, the cell cycle and apoptosis in the human colorectal carcinoma cell line Caco-2. In this report we show that mevastatin combined with butyrate synergistically suppressed growth of Caco-2 cells in a dose- and time-dependent manner. In addition, incubation with mevastatin arrested cells in the G1 phase of the cell cycle after 24 h with a switch to the G2/M phase after 72 h. This was accompanied by a down-regulation of cyclin-dependent kinases (cdk) 4 and cdk 6 as well as cyclin D1, while cdk 2 and cyclin E protein levels remained unchanged during mevastatin treatment. Cell cycle inhibitors p21 and p27 were significantly upregulated by mevastatin. The proapoptotic properties of mevastatin were further enhanced by co-incubation with butyrate. Lastly, the effects of mevastatin could be reversed by addition of mevalonate, but not farnesyl- or geranylgeranylpyrophosphate, intermediate products of cholesterol synthesis, to the medium. These results suggest that HMG-CoA reductase inhibitors like mevastatin may enhance the antiproliferative effect of butyrate in colon cancer cells via induction of apoptosis together with a G0/G1 cell cycle arrest.

Butyrates↗
PubMed2001

Tributyrin, a stable and rapidly absorbed prodrug of butyric acid, enhances antiproliferative effects of dihydroxycholecalciferol in human colon cancer cells.

Tributyrin, a prodrug of natural butyrate, has been evaluated with an aim to overcome pharmacokinetic drawbacks of natural butyrate as a drug, i.e., its rapid metabolization and inability to achieve pharmacologic concentrations in neoplastic cells. We studied the effects of tributyrin on growth, differentiation and vitamin D receptor expression in Caco-2 cells, a human colon cancer cell line. Tributyrin was more potent in inhibiting growth and inducing cell differentiation than natural butyrate. The effect was further enhanced after addition of physiologic concentrations of dihydroxycholecalciferol [(OH)2D3]. The synergistic effect of tributyrin and (OH)2D3 in Caco-2 cells was due to tributyrin-induced overexpression of the vitamin D receptor, as measured by reverse transcriptase-polymerase chain reaction. Treatment with tributyrin increased binding of (OH)2D3 to its receptor 1.5-fold, without any change in receptor affinity. We conclude that tributyrin may, at least in part, exert its growth-reducing and differentiation-inducing effect in Caco-2 cells by an upregulation of the vitamin D receptor; this may provide a useful therapeutic approach in chemoprevention and treatment of colorectal cancer by the two nutrients occurring naturally in human diet.

Alkaline Phosphatase↗
PubMed2001

Downregulation of the cyclin D1/Cdk4 complex occurs during resveratrol-induced cell cycle arrest in colon cancer cell lines.

Resveratrol is a naturally occurring polyphenol with cancer chemopreventive properties. The objective of the current study was to investigate the effect of resveratrol on the human colonic adenocarcinoma cell line Caco-2. The compound inhibited cell growth and proliferation of Caco-2 cells in a dose-dependent manner (12.5-200 micromol/L) as assessed by crystal violet assay, [(3)H]thymidine and [(14)C]leucine incorporation. Furthermore, apoptosis was determined by measuring caspase-3 activity, which increased significantly after 24 and 48 h of treatment with 200 micromol/L resveratrol. Perturbed cell cycle progression from the S to G2 phase was observed for concentrations up to 50 micromol/L, whereas higher concentrations led to reversal of the S phase arrest. These effects were specific for resveratrol; they were not observed after incubation with the stilbene analogs stilbenemethanol and rhapontin. Levels of cyclin D1 and cyclin-dependent kinase (cdk) 4 proteins were decreased, as revealed by immunoblotting. In addition, resveratrol enhanced the expression of cyclin E and cyclin A. The protein levels of cdk2, cdk6 and proliferating cell nuclear antigen were unaffected. Similar results were obtained for the colon carcinoma cell line HCT-116, indicating that cell cycle inhibition by resveratrol is independent of cyclooxygenase inhibition. The phosphorylation state of the retinoblastoma protein in Caco-2 cells was shifted from hyperphosphorylated to hypophosphorylated at 200 micromol/L, which may account for reversal of the S phase block at concentrations exceeding 50 micromol/L. These findings suggest that resveratrol exerts chemopreventive effects on colonic cancer cells by inhibition of the cell cycle.

Alkaline Phosphatase↗
PubMed2001

Deoxycholic acid stimulates migration in colon cancer cells.

BACKGROUND: Deoxycholic acid and other secondary bile acids have long been considered tumour promoters in the colon. However, their effect on cell migration, known to play an important role in colon carcinogenesis, has not been studied so far. OBJECTIVE: To investigate the possible effects of deoxycholic acid on colon cancer-cell migration in culture. METHODS: Human colon carcinoma cells (Caco-2) were seeded on basement membrane matrix. To evaluate replication-blocked cell migration, we wounded confluent monolayers of cells with a sterile scalpel, and inhibited cell replication with mitomycin C. Immediately after wounding, the cells were exposed to 0-100 micromol/l deoxycholic acid. Migration over 72 h was monitored using a phase contrast microscope. RESULTS: Replication-blocked migration was stimulated by deoxycholic acid in a dose-dependent manner, with the maximum effect at 20 micromol/l deoxycholic acid. Enhancement of migration rate was unaffected by immunoneutralization of transforming growth factor beta (a known migration-promoting peptide). However, specific inhibition of protein kinase C markedly inhibited deoxycholic acid-induced Caco-2 cell migration. CONCLUSION: In addition to its well-established role in the enhancement of proliferation, deoxycholic acid also stimulates colon cancer-cell migration along the basement membrane matrix. The mechanism of this stimulation is likely to involve protein kinase C. Deoxycholic acid-stimulated migration might additionally contribute to the tumour-promoting effects of secondary bile acids in the colon.

Caco-2 Cells↗
PubMed2001

Localisation of the subthalamic nucleus using Radionics Image Fusion and Stereoplan combined with field potential recording. A technical note.

Subthalamic nucleus stimulation is an effective therapy for alleviating parkinsonian tremor, rigidity and bradykinesia. Although microelectrode recording is said to be essential for accurate targeting, this often prolongs the operation and the multiple recording tracts required may increase the incidence of complications, particularly haemorrhage. We describe a technique for implantation of deep brain electrodes in the subthalamic nucleus using MRI/CT fusion for anatomical localisation followed by bipolar recording of focal field potentials via the implanted stimulating electrode for neurophysiological confirmation of the stimulation site. The technique is effective, safe and requires much less time, and can be used as an alternative method to microelectrode recording.

Electric Stimulation Therapy↗
PubMed2001

Identification of the Y chromosome in chinook salmon (Oncorhynchus tshawytscha).

The Y chromosome in chinook salmon, Oncorhynchus tshawytscha, was identified using fluorescence in situ hybridization (FISH) with a probe to a male-specific repetitive sequence isolated from this species. The probe highlights the distal end of the short arm of an acrocentric chromosome with a DAPI-bright interstitial band of variable size. The proximal portion of the short arm of the Y chromosome contains 5S rDNA sequences, which are also found on the short arms of six other acrocentric chromosomes in this species.

Animals↗
PubMed2001

Functional recovery after rehabilitation for cerebellar stroke.

BACKGROUND AND PURPOSE: Relatively few data exist concerning functional recovery after ischemic and hemorrhagic cerebellar stroke. We studied patients admitted to a rehabilitation hospital after cerebellar stroke to quantify recovery after rehabilitation therapy and to identify variables that predicted functional outcome. METHODS: This study was a retrospective review of consecutive cases admitted in a 4-year period with new cerebellar infarct or hemorrhage. Clinical features of stroke were recorded and comorbidities scored with the Charlson Index. Follow-up information was obtained by telephone interview. The Functional Independence Measure (FIM) was scored at admission (AFIM), discharge (DFIM), and follow-up (FFIM). Outcome measures were DFIM and FFIM. Univariate and multivariate analyses were performed. RESULTS: Fifty-eight cases were identified (mean age 69.2 years; 49 infarcts, 9 hemorrhages). Mean AFIM was 65.5, and mean DFIM was 89.8. Mean AFIM was significantly higher in the infarct than in the hemorrhage subgroup (70 versus 43, P:=0.006). Mean DFIM was also higher in the infarct subgroup but did not reach statistical significance (93 versus 74, P:=0.1). Follow-up information was obtained for 45 cases (78%) (mean interval 19.5 months). Median FFIM was 123.5. Outcome was significantly positively correlated with AFIM and initial presenting syndrome of vertigo/vomiting/ataxia/headache. Outcome correlated negatively with preexisting comorbidity score, altered level of consciousness at initial presentation, and superior cerebellar artery infarction. On multivariate analysis, AFIM and comorbidity score were independent predictors of outcome. CONCLUSIONS: Substantial improvement of mean FIM score frequently occurs after rehabilitation after cerebellar infarction. Functional outcome is best predicted by preexisting comorbidities and functional status at the time of discharge from acute hospitalization.

Aged↗
PubMed2001

The sensory basis of reading problems.

Learning to read is much more difficult than learning to speak. Most children teach themselves to speak with little or no difficulty. Yet a few years later when they come to learn to read they have to be taught how to do it; they do not pick up reading by themselves. This is because we speak in words and syllables, but we write in phonemes. Syllables do not naturally break down into the sounds of letters and letter units (i.e., phonemes) because these do not correspond to physiologically distinct articulatory gestures (Liberman, Shankweiler, & Studdert-Kennedy, 1967). Alphabetic writing was only invented when people realized that syllables could be artificially divided into smaller acoustically distinguishable phonemes that could be represented by a small number of letters. But these distinctions are arbitrary cultural artifacts, and their mastery was originally confined to a select social class. And until about 100 years ago it did not matter much if the majority of people could not read; the acquisition of reading probably had no serious disadvantages. Reading requires the integration of at least two kinds of analysis (Castles & Coltheart, 1993; Ellis, 1984; Manis, Seidenberg, Doi, McBride-Chang, & Petersen, 1996; Morton, 1969; Seidenburg, 1993). First, the visual form of words, the shape of letters, their order in words, and common spelling patterns, which is termed their orthography, has to be processed visually. Their orthography yields the meaning of familiar words very rapidly without needing to sound them out. But for unfamiliar words, and all words are fairly unfamiliar to the beginning reader, the letters have to be translated into the speech sounds (i.e., phonemes) that they stand for, and then those sounds have to be melded together in inner speech to yield the word and its meaning. Reading exclusively by the phonological route is more time consuming than if words can be accessed directly without requiring phonological mediation.

Auditory Pathways↗
PubMed2001

Hepatotoxicity associated with carvedilol.

OBJECTIVE: To report a severe episode of pruritus and elevated serum transaminases in a patient who was receiving carvedilol. CASE SUMMARY: A 40-year-old white man who had been taking carvedilol for the treatment of cardiomyopathy presented to the emergency department with pruritus over his entire body. Laboratory tests showed elevated serum transaminases. Carvedilol was discontinued and the patient received hydroxyzine hydrochloride to relieve symptoms. Liver function test results returned to normal in three weeks. Approximately one year later the patient was started on metoprolol and within 10 days again developed pruritus. The patient was told to discontinue the metoprolol immediately. At the time the metoprolol was stopped the liver function test results were normal. DISCUSSION: To the best of our knowledge, the adverse reaction presented in this case report is rare. The etiology of this adverse reaction remains unknown but suggests a possible adverse reaction that may recur if the patient is switched to another beta-adrenergic blocker. The liver function test abnormalities appear to return to normal on discontinuation of carvedilol. CONCLUSIONS: Carvedilol may cause pruritus and elevated liver function test results. This reaction may recur if the patient is changed to an alternative beta-adrenergic blocker. Patients taking carvedilol should be monitored for signs and symptoms of hepatotoxicity. If elevated liver function test results are noted, carvedilol should be discontinued.

Adrenergic beta-Antagonists↗
PubMed2001

Prevalence of incidental Bochdalek's hernia in a large adult population.

OBJECTIVE: The purpose of this study was to determine the prevalence and characteristics of adult Bochdalek's hernia in a large patient population. MATERIALS AND METHODS: We retrospectively reviewed all abdominal CT scans obtained at our hospital in 1998. Patients in our study were identified through a keyword search of our database for "Bochdalek," "hernia," and "diaphragm." The individual patient studies identified were reviewed in a soft-copy format. We noted the location and side of the body on which the diaphragmatic hernia arose and the contents of the sac. We also performed a chart review for each patient included in the study, noting the patient's sex, age, and symptoms. RESULTS: Incidental Bochdalek's hernia was diagnosed in 22 patients (17 women, five men), which represents an incidence of 0.17% based on 13,138 abdominal CT reports we reviewed. The mean age of the patients was 66.6 years. None of the patients were symptomatic. Sixty-eight percent of the hernias were on the right side of the body, 18% were on the left side, and 14% were bilateral. Seventy-three percent contained only fat or omentum, whereas 27% had solid or enteric organ involvement including the spleen, small intestine, or large intestine. CONCLUSION: Bochdalek's hernia is not rare, and the incidence of Bochdalek's hernias that contain enteric tract is higher than previously reported. This incidence likely represents a conservative estimate because some Bochdalek's hernias may have been overlooked or unreported.

Aged↗
PubMed2001

Transepithelial transport of putrescine across monolayers of the human intestinal epithelial cell line, Caco-2.

AIM: To study the transepithelial transport characteristics of the polyamine putrescine in human intestinal Caco-2 cell monolayers to elucidate the mechanisms of the putrescine intestinal absorption. METHODS: The transepithelial transport and the cellular accumulation of putrescine was measured using Caco-2 cell monolayers grown on permeable filters. RESULTS: Transepithelial transport of putrescine in physiological concentrations (> 0.5 mM) from the apical to basolateral side was linear. Intracellular accumulation of putrescine was higher in confluent than in fully differentiated Caco-2 cells, but still negligible (less than 0.5%) of the overall transport across the monolayers in apical to basolateral direction.EGF enhanced putrescine accumulation in Caco-2 cells by four fold, as well as putrescine conversion to spermidine and spermine by enhancing the activity of S adenosylmethionine decarboxylase. However, EGF did not have any significant influence on putrescine flux across the Caco-2 cell monolayers. Excretion of putrescine from Caco-2 cells into the basolateral medium did not exceed 50 picomoles, while putrescine passive flux from the apical to the basolateral chamber, contributed hundreds of micromoles polyamines to the basolateral chamber. CONCLUSION: Transepithelial transport of putrescine across Caco2 cell monolayers occurs in passive diffusion, and is not influenced when epithelial cells are stimulated to proliferate by a potent mitogen such as EGF.

Biological Transport↗
PubMed2000

Interaction of CBF alpha/AML/PEBP2 alpha transcription factors with nucleosomes containing promoter sequences requires flexibility in the translational positioning of the histone octamer and exposure of the CBF alpha site.

Chromatin remodeling at eukaryotic gene promoter sequences accompanies transcriptional activation. Both molecular events rely on specific protein-DNA interactions that occur within these promoter sequences. Binding of CBFalpha/AML/PEBP2alpha (core binding factor alpha/acute myelogenous leukemia/polyoma enhancer binding protein 2alpha) proteins is a key event in both tissue-specific and developmentally regulated osteocalcin (OC) promoter activity. To address linkage between chromatin organization and transcription factor binding, we reconstituted segments of the rat OC gene proximal promoter into mononucleosomes and studied binding of CBFalpha proteins. We analyzed binding of bacterially produced Cbfalpha2Alpha and Cbfalpha2B, two splice variants of the human CBFalpha2 gene, and determined the effect of heterodimerization with the Cbfbeta subunit on binding activity. Our results indicate that binding of the truncated Cbfalpha2A protein to naked DNA is independent of Cbfbeta whereas Cbfalpha2A binding to nucleosomal DNA was enhanced by Cbfbeta. In contrast, the Cbfalpha2B interaction with either naked or nucleosomal DNA was strongly dependent on heterodimerization with the Cbfbeta subunit. Additionally, our results demonstrate that both Cbfalpha2A alone and Cbfalpha2B complexed with Cbfbeta can interact with nucleosomal DNA only if there is a degree of flexibility in the positioning of the histone octamer on the DNA fragment and exposure of the CBFalpha site. This situation was achieved with a DNA segment of 182 bp from the rat OC promoter that preferentially positions mononucleosomes upstream of the CBFalpha binding site and leaves this element partially exposed. Taken together, these results suggest that nucleosomal translational positioning is a major determinant of the binding of CBFalpha factors to nucleosomal DNA.

Animals↗
PubMed2000

Renal cell carcinoma metastatic to the pancreas: a single-institution series and review of the literature.

OBJECTIVES: To present a series of 5 patients with solitary metastatic renal cell carcinoma (RCC) to the pancreas after radical nephrectomy at our institution and review the published reports of this rare event. METHODS: A retrospective review of the records of 5 patients with histologically confirmed RCC metastatic to the pancreas after radical nephrectomy was performed. A total of 5 patients (4 men, 1 woman) with a median age of 56 years (range 54 to 68) underwent radical nephrectomy for primary RCC. The pathologic stage was Robson I (n = 3) or Robson III (n = 2), with a left-sided tumor occurring in 3 patients and a right-sided tumor in 2 patients. The median interval from nephrectomy to the diagnosis of the pancreatic metastasis was 12 years (range 4 to 15). All patients were symptomatic at presentation, including weight loss (n = 3), abdominal pain (n = 3), early satiety (n = 1), steatorrhea (n = 1), and/or hemosuccus pancreaticus (n = 1). RESULTS: All pancreatic metastases were hypervascular on imaging studies, and surgical removal was accomplished by pancreaticoduodenectomy (n = 3), partial pancreatectomy (n = 1), or subtotal pancreatectomy (n = 1). One patient died of disseminated disease 12 months after pancreatic resection. Two other patients had recurrences in the lung (n = 1) at 5 months or the pancreas/liver (n = 1) at 48 months. Both of these patients underwent a second resection and were disease free at 2 and 12 months afterward. The two remaining patients were disease free at 7 and 24 months after pancreatic resection. CONCLUSIONS: RCC is an unpredictable tumor that may demonstrate very late metastases even from early-stage lesions. Aggressive surgical management of isolated pancreatic lesions offers a chance of long-term survival.

Aged↗