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Biomedical subjects

J Stein

Publications and source records attributed to J Stein.

At least 73 records · Page 4Linked to original sources
PubMed2001

Near haploid childhood acute lymphoblastic leukemia masked by hyperdiploid line: detection by fluorescence in situ hybridization.

Near-haploid (<30 chromosomes) acute lymphoblastic leukemia (ALL) is a rare and unique subgroup of childhood common ALL associated with a very poor outcome. It may be underdiagnosed when masked by a co-existing hyperdiploid line, which has to be distinguished from the common good-prognostic hyperdiploid (>50 chromosomes) ALL. We present three children in whom, by conventional cytogenetics, near-haploid ALL was detected on relapse. Using interphase FISH probes of chromosomes X, Y, 4, 12, and 21, we were able, in two cases, to trace the hidden near-haploid lines of approximately 5% and 20% of the cells, masked by hyperdiploid cells of approximately 80% and 70%, respectively; at relapse, the proportion was reversed, with predominant near-haploid lines of over 80% and residual hyperdiploidy of less than 10%. The near-haploid lines consisted of 24 and 27 chromosomes, and always retained the second copy of chromosome 21 or its derivative, as detected in one of our patients by SKY. The hyperdiploid clones were the exact duplicates of the near-haploid ones and contained four and two copies of the chromosomes represented in two and one copies in the near-haploid stem line, respectively. Unlike the common hyperdiploid ALL, no trisomies were observed. The patients were all aged >10 years, with WBC 0.7-30 x 10(9)/L, and a common ALL phenotype. They were treated with the ALL-BFM-95 protocol, medium risk group, and responded well to 8 days of steroid therapy, but relapsed early, within 11 months, and died a few months later. Interphase FISH technique is recommended for the detection of cryptic near-haploid clones in the diagnostic survey of ALL. To assess the prognostic value of near-haploidy in the context of the ALL-BFM protocols, a larger cohort of patients is required.

Adolescent↗
PubMed2001

1,25-Dihydroxycholecalciferol enhances butyrate-induced p21(Waf1/Cip1) expression.

Butyrate, a short-chain fatty acid produced in the colon, as well as its prodrug tributyrin, reduce proliferation and increase differentiation of colon cancer cells. p21(Waf1/Cip1) and p27(Kip1) are negative regulators of cell cycle and are thought to have a key function in the differentiation of various cell lines. We studied the effects of butyrate on differentiation, VDR expression, as well as on p21(Waf1/Cip1) and p27(Kip1) expression in human colon cancer cells (Caco-2). Butyrate induced cell differentiation, which was further enhanced after addition of 1,25-dihydroxycholecalciferol. Synergistic effect of butyrate and dihydroxycholecalciferol in Caco-2 cells was due to butyrate-induced overexpression of VDR. While butyrate as well as dihydroxycholecalciferol increased p21(Waf1/Cip1) and p27(Kip1) expression, in contrast combined exposure of butyrate and dihydroxycholecalciferol resulted in a synergistic amplification of p21(Waf1/Cip1), but not of p27(Kip1) expression. These data imply that butyrate selectively increases p21(Waf1/Cip1) expression via upregulation of VDR in Caco-2 cells.

Alkaline Phosphatase↗
PubMed2001

Butyrate-induced differentiation of Caco-2 cells occurs independently from p27.

Butyrate, a short-chain fatty acid produced in the colon, reduces proliferation and increases differentiation of colon cancer cells. p27, an inhibitor of cyclin-dependent kinases and a negative regulator of the cell cycle, is thought to have a key function in the differentiation of various cell lines. The objective of the present study was to elucidate the role of p27 in butyrate-induced differentiation of the human colorectal carcinoma cell line Caco-2. In this report we show that in spite of the increase in p27 protein expression after incubation with the HMG-CoA reductase inhibitor mevastatin, alkaline phosphatase activity decreases significantly in this cell line. In addition, mevastatin caused a significant increase in the cell cycle inhibitor p21. All effects could be reversed by addition of mevalonate to the medium. Taken together, we provide the first evidence that in Caco-2 cells p27 may have other functions apart from the regulation of cell differentiation.

Apoptosis↗
PubMed2001

Hydroxylamine-containing inhibitors of polyamine biosynthesis and impairment of colon cancer cell growth.

Polyamine synthesis (by the action of ornithine decarboxylase [ODC] and S-adenosylmethionine decarboxylase [SAMDC]) and polyamine content are high in colon cancer. In addition, colonic lumen is rich in polyamines synthesised by colonic microflora; for this reason, polyamine depletion in colon cancer may be a logical approach to impair growth of colon cancer cells. We evaluated highly specific and reportedly non-toxic hydroxylamine-containing inhibitors of ODC (1-aminooxy-3-aminopropane, APA) and SAMDC (S-(5'-deoxy-5'-adenosyl)-methylthioethyl-hydroxylamine, AMA) in human colon cancer cells (Caco-2 and HT-29) in culture. APA depleted ODC activity within 24 hr, more rapidly than did difluoromethylornithine. APA and AMA in combination (100 microM each) reduced ODC and SAMDC activities to undetectable levels within 24 hr and intracellular polyamines to 8-23% of control. The resulting growth arrest could be reversed only by twice as much spermidine as is physiologically present in the colonic lumen. In concentrations sufficient to deplete growth, APA and AMA were not toxic. Simultaneous treatment with APA, AMA, and 5-fluorouracil reduced colon cancer cell survival more potently than treatment with 5-fluorouracil alone. The hydroxylamine-containing ODC and SAMDC inhibitors APA and AMA are potent inhibitors of colon cancer cell proliferation and might be therapeutically promising in colon cancer.

Adenosylmethionine Decarboxylase↗
PubMed2001

Nasal cavity squamous cell carcinoma in Wegener's granulomatosis.

Wegener's granulomatosis is a chronic debilitating disease with multiple organ system involvement, variable course, and myriad complications that cause morbidity and mortality. We report 2 cases of nasal cavity squamous cell carcinoma occurring in long-standing Wegener's granulomatosis.

Adult↗
PubMed2001

Flux of amino acids and energy substrates across the leg in weight-stable HIV-infected patients with acute opportunistic infections: indication of a slow protein wasting process.

Increased whole-body proteolysis with muscle protein net degradation has been suggested as one of the causes of weight loss in patients infected with human immunodeficiency virus (HIV). We studied the exchange rates of amino acids and energy substrates across the lower extremity in 16 HIV patients and 16 age-matched controls with similar body cell mass. The patients had either opportunistic infections or chronic diarrhea but no signs of clinical malnutrition. The following findings were obtained in the HIV patients: an augmented peripheral net release of arginine and lysine; an increase in both the negative arterial-venous difference and the efflux of the nitrogen contained in nonmetabolized amino acids; diminished export of 3-methylhistidine; lowered plasma and erythrocyte amino acid concentrations; reduced output of glycerol and furthermore; and neither a net release nor a net uptake of free fatty acids. The findings concerning nitrogen metabolism support the hypothesis that, in the presence of a reduction in protein breakdown, peripheral protein synthesis is severely depressed, making a slow protein wasting process likely to occur. The balances of glycerol and free fatty acids are due not only to the leg tissues but perhaps also in part to increased net retention of these substrates by skeletal muscle.

AIDS-Related Opportunistic Infections↗
PubMed2001

Capillary zone electrophoresis of proteins with poly(2-hydroxyethyl methacrylate)-coated capillaries: fundamental and applications.

Fused silica capillaries have been modified by atom-transfer radical polymerization (ATRP) to generate covalently bonded polymer films of 2-hydroxyethyl methacrylate. Because the kinetics of ATRP have mainly been investigated in bulk solutions, a GC experiment was set up to examine monomer conversion inside narrow-bore capillaries. It was shown that after 1 to 4 h the reaction was nearly complete. The coating process was further optimized by monitoring EOF, because low EOF indicates high surface coverage. To deal with the very low EOF values, a new approach was used to dramatically reduce the measurement time by overlaying hydrodynamic flow on the electroosmotic flow. The corresponding equations are derived separately in detail. Capillaries were then coated under optimum conditions with linear or cross-linked polymer films. The EOF was reduced over a wide range of pH values. A long-term reproducibility test with both types of functionalization showed that the efficiency of the linear polymer coating decreased significantly over time. With cross-linked films, however, the efficiency even increased. Relative standard deviations for protein migration times were also much lower in cross-linked coated capillaries. Highly efficient separations could be performed for basic and acidic proteins in acidic media, and for the latter even in basic media.

Electrophoresis, Capillary↗
PubMed2001

Implementing AIDS policy in post-apartheid South Africa.

In common with the rest of the Southern African sub-continent. South Africa is currently experiencing a serious HIV epidemic. When it came into power in 1994, the new, Mandela-led government immediately mobilised funds and adopted a far-reaching AIDS Plan for the country. However, the implementation of AIDS policy in the first four years after 1994 has been characterised by a lack of progress and a breakdown of trust and co-operation, both within government and between government and NGOs. This paper outlines the political context which shaped the development of the AIDS Policy, then examines the difficulties of implementing a comprehensive response to AIDS in a country undergoing restructuring at every level. It questions the notion of "inadequate political will" as an explanation for lack of progress. Involvement by politicians has, in fact, been experienced as a double-edged sword in South Africa, with inappropriate, "quick-fix" actions creating conflict and hampering a more longer-term, effective response. The paper also highlights the importance of groupings outside of government in promoting effective policy actions, and the types of leadership required to mobilise a broad range of actors around a common vision. It concludes by emphasising the need to develop approaches to policy implementation rooted in the possibilities and constraints of the local situation, rather than relying on universal blue-prints developed out of context.

Communicable Disease Control↗
PubMed2001

Decreased oxidative stress in patients with idiopathic dilated cardiomyopathy one year after immunoglobulin adsorption.

OBJECTIVES: In a substudy to a recently reported investigation that demonstrated the benefit of immunoglobulin adsorption (immunoadsorption) for patients with idiopathic dilated cardiomyopathy (IDC), we tested whether this benefit is associated with a reduction of oxidative stress. BACKGROUND: The progression of cardiomyopathy is believed to be related to the increase of oxidative stress. Therefore, reduction of oxidative stress could be one of the effects of immunoadsorption for improvement of cardiac performance and clinical status. METHODS: Plasma markers for oxidative stress-thiobarbituric acid-reactive substances (TBARS), lipid peroxides (LPO), anti-oxidized low-density lipoprotein-autoantibodies (anti-oxLDL-AB), thiol groups and vitamin E-were compared in 31 patients, of whom 16 underwent immunoadsorption and 15 received conventional treatment (controls). All patients received a daily supplement of vitamins, minerals and trace elements. RESULTS: After one year, TBARS (p = 0.026), LPO (p = 0.026) and anti-oxLD

Adsorption↗
PubMed2001

Permeability characteristics of polyamines across intestinal epithelium using the Caco-2 monolayer system: comparison between transepithelial flux and mitogen-stimulated uptake into epithelial cells.

The polyamines putrescine, spermidine, and spermine are present in foods in high amounts, and are used for cell growth throughout the body. Surprisingly little is known about the mechanisms of polyamine absorption in the gut. To elucidate the mechanisms, transepithelial transport of polyamines was studied in human enterocytelike Caco-2 cells, grown on permeable filter supports. Transport of all three polyamines across Caco-2 cell monolayers was linear; intraepithelial accumulation of polyamines was higher in confluent than in differentiated Caco-2 cells, but still negligible in comparison with the overall transport across the monolayers. Epidermal growth factor (EGF) enhanced polyamine accumulation in Caco-2 cells four-fold, and basolateral uptake was higher than apical uptake if the cells were stimulated to grow. The amounts of polyamines taken up by the cells were nevertheless negligible in comparison with the net polyamine flux across the monolayers. Basolateral excretion of polyamines was in the picomolar range, whereas their transepithelial transport, occurring presumably by passive diffusion through the paracellular pathway, contributed hundreds of micromoles of polyamines to the basolateral chamber. We conclude that transepithelial transport of polyamines occurs by passive diffusion, and that it is not influenced when epithelial cells are stimulated to proliferate by a potent mitogen such as EGF.

Biological Transport↗
PubMed2001

Postoperative course of S-100B protein and neuron-specific enolase in patients after implantation of continuous and pulsatile flow LVADs.

BACKGROUND: In the early post-operative period after implantation of a continuous flow left ventricular assist device (LVAD) a non-pulsatile flow occurs. We compared the post-operative time-courses of protein S-100B (S100B) and neuron-specific enolase (NSE) as biochemical markers of brain injury in patients after implantation of a continuous flow LVAD and patients receiving a pulsatile flow LVAD. METHODS: Since 1998 the continuous flow DeBakey VAD has been implanted in 8 patients at our institution. For comparison purposes, a group of 7 consecutive patients in whom a pulsatile Novacor N100 LVAD was implanted were investigated. In both groups cardiopulmonary bypass (CPB) with cardiotomy suction was used. S100B and NSE were measured in serum pre-operatively, 4 hours after CPB, and on days 1, 3, 7, and 14 after implantation of the LVAD. A neurologic examination was performed pre-operatively and post-operatively on days 3 and 14. RESULTS: No differences were found between groups in pre-operative characteristics. The analysis of variance with repeated measurements for S-100B and NSE showed significant time effects (p = 0.004, p = 0.009, respectively) but no group effects (p = 0.06, p = 0.26, respectively) and no interaction between groups and time (p = 0.12, p = 0.48, respectively). The pre-operative serum level of S100B was significantly higher (p = 0.03) in the DeBakey VAD group. The pre-operative serum level of NSE was similar in the 2 groups (p = 0.7). In both groups there was a significant increase of S100B and NSE immediately after surgery (S100B: p = 0.006, p = 0.019; NSE: p = 0.01, p = 0.001). The values returned to pre-operative levels in the DeBakey VAD group on day 1 after implantation and in the Novacor group for S100B on day 3 and NSE on day 1. Post-operatively the mean values of S100B and NSE in the DeBakey VAD group compared with the Novacor group were significantly elevated only on day 3 (p = 0.005, p = 0.023).No neurologic complications were noted in patients with a continuous flow LVAD, whereas in the pulsatile LVAD group 2 patients presented neurologic abnormalities during the study period. CONCLUSIONS: The similar course of biochemical markers of brain damage in both groups may indicate that the non-pulsatile flow in the early post-operative period does not lead to increased brain injury or permeability of the brain blood barrier.Elevated levels of S100B and NSE in the post-operative period can be used as diagnostic markers of brain injury in patients after implantation of both types of LVAD.

Adult↗
PubMed2001

Phase I and pharmacokinetic study of hepatic arterial infusion with oxaliplatin in combination with folinic acid and 5-fluorouracil in patients with hepatic metastases from colorectal cancer.

BACKGROUND: To determine dose-limiting toxicity (DLT), maximum tolerated dose (MTD), and pharmacokinetics (PK) of oxaliplatin administered as hepatic arterial infusion. PATIENTS AND METHODS: Patients with isolated hepatic metastases from colorectal cancer were treated every three weeks with increasing doses of oxaliplatin (4 hours; starting dose 25 mg/m2, escalation in steps of 25 mg/m2) in combination with folinic acid (1 hour, 200 mg/m2) and 5-fluorouracil (2 hour, 600 mg/m2). RESULTS: Twenty-one patients (median age, 61 years) have been entered all of whom are fully evaluable. The DLT has been observed at dose level 6, i.e., at 150 mg/m2/cycle and consisted of leucopenia, obliteration of the hepatic artery, and acute pancreatitis. Overall, toxicity mainly consisted of nausea/vomiting (16 of 21 patients), anemia (16 of 21), upper abdominal pain (15 of 21), sensory neuropathy (10 of 21), diarrhea (9 of 21), and thrombocytopenia (9 of 21). The mean PK parameters were: terminal half-life of ultrafiltrable platin, 17.75 +/- 9.29 hours; renal elimination, 48.7% +/- 14.1% of the applied dose; renal clearance 135.55 +/- 45.32 ml/min. The mean area under the plasma-concentration curve (AUC) increased linearly from 3.22 +/- 0.61 microg x h/ml to 18.45 +/- 8.90 microg x h/ml through the first five dose levels (P = 0.0004). Ten of eighteen evaluable patients achieved a complete or partial response (59%). CONCLUSIONS: The recommended dose for phase II studies is 125 mg/m2 oxaliplatin.

Adult↗
PubMed2001

Yield of bronchoalveolar lavage in ventilated and non-ventilated children after bone marrow transplantation.

A study was undertaken to retrospectively evaluate the yield of bronchoalveolar lavage (BAL) in a single-institution series of children after bone marrow transplantation (BMT) and to compare the yield of BAL between the ventilated and nonventilated patients. We reviewed charts of 52 consecutive children after BMT who underwent BAL. Thirty patients (41 BALs) were nonventilated (group 1) and 33 patients (45 BALs) were ventilated for respiratory failure (group 2). Eleven patients were included in both groups. BAL was performed a median of 255 and 28.5 days after BMT in groups 1 and 2, respectively (P < 0.001). Group 1:17 pathogens were isolated from 13 BALs; a single pathogen from 10 BALs. Group 2:15 pathogens were isolated from 14 BALs (31.1% positive). Viruses were isolated from 13 BALs in group 2. A severe complication of BAL occurred in only one patient from group 1 (1.1%). Open lung biopsies were performed in one patient in group 1 and eight patients in group 2. The histological findings correlated with the BAL findings in 66.7%. In conclusion, there was no difference in the yield of BAL between the groups. Therapy was changed in one third of the patients dictated by the BAL findings. The risk of severe complications was relatively low. A good correlation between open lung biopsy (OLB) and BAL was found.

Bone Marrow Transplantation↗
PubMed2001

Accidental busulfan overdose: enhanced drug clearance with hemodialysis in a child with Wiskott-Aldrich syndrome.

A 4.6 kg infant with Wiskott-Aldrich syndrome received an accidental overdose of busulfan during preparation for allogeneic stem cell transplantation. Pharmacokinetic analysis of plasma busulfan levels alerted staff to the dosing error. Hemodialysis was immediately performed and resulted in accelerated clearance of busulfan. There were no acute neurologic and hepatic side-effects of the busulfan overdose, and despite 2 months of cough accompanied by rales, the patient is now free of pulmonary symptoms. Stable partial donor chimerism occurred after transplantation. At present, the patient is thriving and infection-free 12 months after transplantation, although his platelet count remains at the lower limit of normal.

Area Under Curve↗
PubMed2001

Nonsteroidal anti-inflammatory drugs stimulate spermidine/spermine acetyltransferase and deplete polyamine content in colon cancer cells.

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit colonic tumourigenesis and have an established usefulness in cancer prevention. Because polyamines are essential for neoplastic cell growth, the aim of this study was to evaluate the effect of NSAIDs (indomethacin, a nonselective COX-1 and COX-2 inhibitor) on polyamine metabolism in colon cancer cells. METHODS: Both cell counting and thymidine incorporation into cellular DNA were used to assess colon cancer cell growth. Activities of polyamine-metabolising enzymes, polyamine content (HPLC) and ODC and c-myc protein expression (Western blot) were measured in colon cancer cells treated with indomethacin during logarithmic phase of proliferation. RESULTS: Indomethacin impaired growth of human colon cancer cells (Caco-2 and HCT-116). As a result, ornithine decarboxylase activity and c-myc protein expression were decreased. Treatment with indomethacin induced intracellular oxidant formation in colon cancer cells significantly increased the spermidine/spermine-acetyltrasferase activity (SSAT) and enhanced polyamine acetylation and efflux from colon cancer cells. Impairment of cell growth by indomethacin could not be reversed by exogenous polyamines. CONCLUSION: Taken together, our results suggest that NSAIDs affect polyamine metabolism in colon cancer cells by inducing SSAT activity, and that polyamine depletion in NSAID-treated colon cancer cells is mainly due to enhanced polyamine acetylation and irreversible depletion of intracellular polyamine pools.

Acetylation↗