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Biomedical subjects

G Schwartz

Publications and source records attributed to G Schwartz.

At least 91 records · Page 5Linked to original sources
PubMed1993

A missense mutation, S349P, completely inactivates phenylalanine hydroxylase in north African Jews with phenylketonuria.

The majority of hyperphenylalaninemias (HPAs) result from mutations at the gene for phenylalanine hydroxylase (PAH). The broad phenotypic variability of these conditions, ranging from phenylketonuria (PKU) to mild benign HPA, is underlain by a wide spectrum of mutations giving rise to various genotypic combinations. Mutant PAH alleles, labeled by specific polymorphic haplotypes and mutations, are becoming useful markers in human population genetics. We report here a mutant PAH allele found in Jews from Morocco and Tunisia, marked by haplotype 4 and a missense mutation, TCASer-->CCAPro, at codon 349 in exon 10 of the gene. In vitro expression of the mutation showed normal levels of mRNA with virtually no enzymatic activity or protein immunoreactivity, pointing to a highly unstable protein. A homozygote for this mutation showed the most severe ("classical") type of PKU, while compound heterozygotes showed two other types of HPA--"atypical" PKU and "high benign" HPA--illustrating the interplay between different mutations that gives rise to various HPAs.

Base Sequence↗
PubMed1993

Histamine-activated, non-selective cation currents and Ca2+ transients in endothelial cells from human umbilical vein.

Permeation properties and modulation of an ionic current gated by histamine were measured in single endothelial cells from human umbilical cord veins by use of the patch-clamp technique in the ruptured-whole-cell mode or using perforated patches. We combined these current measurements with a microfluorimetric method to measure concomitantly free intracellular calcium concentration ([Ca2+]i). Application of histamine induced an intracellular calcium transient and an ionic current that reversed near 0 mV. The amplitude of the current ranged from -0.2 to -2 nA at -100 mV. The tonic rise in [Ca2+]i and the ionic current are partly due to Ca2+ influx. This Ca2+ entry pathway is also permeable for Ba2+ and Mn2+. The amplitude of the histamine-activated current was also closely correlated with the amplitude of the concomitant Ca2+ transient, suggesting that the latter is at least partially due to Ca2+ influx through histamine-activated channels. The reversal potential of the histamine-induced current was 7.6 +/- 4.1 mV (n = 14) when the calcium concentration in the bath solution ([Ca2+]o) was 1.5 mmol/l. With 10 mmol/l [Ca2+]o it was -13.7 +/- 4.7 mV and shifted to + 13.0 +/- 1.5 mV in nominally Ca(2+)-free solution (n = 3 cells). The amplitude of the current in Ca(2+)-free solution was enhanced compared to that in 10 mmol/l [Ca2+]o. The shift of the reversal potential and the concomitant change of the current amplitude suggest that the channel is permeable for calcium but has a smaller permeability for calcium than for monovalent cations.(ABSTRACT TRUNCATED AT 250 WORDS)

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1993

Substance abuse in adolescent trauma.

STUDY OBJECTIVE: To determine if there is a significant prevalence of drug or alcohol use among adolescents evaluated for significant acute trauma. DESIGN: A prospective, age-matched controlled study over a 20-month period. SETTING: Urban pediatric emergency department in a Level I pediatric trauma center. PARTICIPANTS: Patients between 13 and 19 years of age requiring admission to the trauma service following evaluation in a pediatric ED and an age-matched control group of asthmatic patients. RESULTS: A total of 134 patients (mean age, 14.8 years) were admitted for trauma-related injuries, and 22 of 65 (34%) were positive for alcohol or drugs of abuse. The mean age of patients with a positive toxicology screen was 15.4 years. Most commonly detected drugs were alcohol (eight), benzodiazepines (eight), cocaine (five), and cannabinoids (four). The number of positive screens in the trauma group (22 of 65) was significantly higher than controls (one of 49) (P < .001). This remained statistically significant even when those trauma patients not screened were assumed to have a negative toxicology screen (22 of 134 versus one of 49) (P < .01). There was also a significantly higher number of positive toxicology screens among adolescents with an intentional versus unintentional mechanism of injury (21 of 71 versus one of 63) (P < .001). CONCLUSION: A significant number of adolescents admitted to the hospital for trauma-related injuries have a toxicology screen positive for alcohol or drugs of abuse. A toxicology screen should be a standard laboratory test in adolescents involved in significant trauma, especially if the mechanism was intentional.

Acute Disease↗
PubMed1993

The use of G-CSF or GM-CSF mobilized peripheral blood progenitor cells (PBPC) alone or to augment marrow as hematologic support of single or multiple cycle high-dose chemotherapy.

High dose chemotherapy with autologous bone marrow support (ABMT) can achieve prolonged relapse-free survival in relapsed lymphomas, leukemias, and certain solid tumors. The principal morbidity and mortality relate to the infectious complications that occur during the 3-4 week aplasia until the marrow autograft recovers. Progenitor cells can be mobilized into the peripheral blood compartment by hematopoietic growth factors, used alone or after chemotherapy. We describe four trials using cytokine-mobilized peripheral blood progenitor cells (PBPC). In the first trial, PBPC collected after GM-CSF administration were used to augment marrow. Reconstitution of trilineage marrow function occurred promptly, resulting in short hospital stays and fewer platelet transfusions. In a second study, GM-CSF/chemotherapy-mobilized PBPC were used as the sole hematopoietic support during high dose chemotherapy. Granulocyte and platelet reconstitution was rapid. Time to hematopoietic recovery, transfusion requirements, and duration of hospital stay were all significantly improved for the patients receiving PBPC compared with similar patients receiving marrow alone. While most patients experienced prompt hematopoietic recovery they showed sluggish platelet engraftment. The next two trials built on the observation that a few PBPC alone could support both granulocyte and platelet recovery and were designed to test the feasibility of sequential high-dose therapies. In one trial, PBPC given with and without marrow made it possible to deliver two sequential cycles of high-dose therapy. The second trial utilized PBPC plus cytokines to deliver four cycles of dose-intensive chemotherapy at doses that could not be given with cytokine support alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

High-dose chemotherapy with autologous stem cell support for breast cancer: a review of the Dana-Farber Cancer Institute/Beth Israel Hospital experience.

The overall median survival of women with advanced or high-risk primary breast cancer has not changed with conventional chemotherapy. Regimens employing high-dose chemotherapy with autologous stem cell support (ABMT) have been developed with the hope of optimizing tumor response and increasing survival. Early phase I studies in women with advanced refractory disease achieved high response rates of short duration. Second generation studies combined an induction phase followed by one high-dose intensification at time of maximum tumor response. The Dana-Farber Cancer Institute/Beth Israel Hospitals have developed the high-dose intensification regimen of cyclophosphamide, thiotepa, and carboplatin (CTCb) for use in women with metastatic and high-risk stage IIIB/inflammatory breast cancer. To date, approximately 19% of women with metastatic disease remain progression free using this approach, with median length of follow-up approaching 40 months. Although the median duration of follow-up for the stage IIIB women is much shorter (approximately 12 months), greater than 90% of these women are thus far disease free. With the advent of hematologic support, such as blood stem cells and colony-stimulating factors, the morbidity, mortality, and costs associated with this treatment have been substantially reduced, allowing for two or more cycles of high-dose intensification to be employed, to exploit the potential of dose-intensity to optimize response.

Adenocarcinoma↗
PubMed1993

A comparison of the cardiac safety and therapeutic efficacy of trimipramine versus doxepin in geriatric depressed patients.

OBJECTIVE: To compare the cardiac safety and therapeutic efficacy of trimipramine and doxepin. DESIGN: A 1-week single-blind placebo period followed by a 5-week randomized double-blind parallel group clinical trial. SETTING: Psychiatric out-patient clinic of a general hospital. PATIENTS: 37 young-elderly patients with a diagnosis of Major Depressive Episode (DSM-III criteria). INTERVENTIONS: Placebo for 1 week, 2 weeks of titration with either drug in the dosage range of 75 mg/day up to a maximum of 200 mg/day. MEASUREMENTS: We measured the psychiatric effects with the Hamilton Rating Scale for Depression, the Hamilton Anxiety Rating Scale, and the Clinical Global Impression Scale. Cardiovascular effects were assessed on 12-lead standard electrocardiograms plus 1-minute rhythm and high speed recordings; orthostatic (lying/standing) blood pressures were also taken. Physical exams, lab tests, cognitive functions (Buschke Selective Reminding Test, Hierarchic Dementia Scale, Word Fluency) and adverse reactions were also noted. RESULTS: Both drugs were equally effective in relieving symptoms of depression and anxiety. The cardiovascular effects of both drugs were minimal. Trimipramine did lower blood pressure but this was without clinical significance. Three trimipramine patients and five doxepin patients developed occasional premature ventricular or atrial contractions. Of these, two trimipramine patients and one doxepin patient were among those with abnormal ECG's at entry. The doxepin patient was withdrawn from the study after 21 days of treatment when the PVC's became increasingly frequent. CONCLUSIONS: Trimipramine and doxepin are equally safe and effective antidepressants in the young-elderly.

Age Factors↗
PubMed1993

Phenylketonuria: variable phenotypic outcomes of the R261Q mutation and maternal PKU in the offspring of a healthy homozygote.

Phenylketonuria (PKU) and benign hyperphenylalaninaemia (HPA) result from a variety of mutations in the gene for the hepatic enzyme phenylalanine hydroxylase. PKU has been found in the Israeli population in two variants, classical and atypical. The two are clinically indistinguishable and require treatment with low phenylalanine diet to prevent mental retardation, but show differences in serum phenylalanine levels and in tolerance to this amino acid. Maternal PKU is a syndrome of congenital anomalies and mental retardation that appears in offspring of PKU mothers as a result of fetal exposure to the high phenylalanine level in the maternal blood. We studied a family in which two children with severe, classical PKU and their unaffected brother showed mild signs of maternal PKU. Their mother had no clinical signs of PKU, but the phenylalanine concentration in her serum reached a level that usually characterises PKU patients. This woman represents a rare phenotype, benign atypical PKU. Such 'hidden' PKU in women may lead to maternal PKU in the offspring, similar to overt PKU. Special attention should therefore be paid to women having children with any of the clinical hallmarks of maternal PKU, and to children born to women known to have benign HPA. The mother was also found to be homozygous for a missense mutation at the phenylalanine hydroxylase locus, R261Q, which does not abolish enzymatic activity completely. In two other families, homozygosity for this mutation resulted in atypical PKU in four children. This observation suggests that mutations that do not completely destroy phenylalanine hydroxylase activity may exhibit variable phenotypic expression which is unpredictable. Compound heterozygosity for R261Q and other mutations led in other patients either to classical PKU or to mild benign HPA.

Adult↗
PubMed1993

Effect of scopolamine on spontaneous yawning in men.

The effect of scopolamine hydrobromide (0.4 mg s.c.) on spontaneous yawning was studied in 16 male volunteers in a double-blind study. Scopolamine (or placebo) was given 60 min before (-60 min) placebo (physiological saline s.c.) (time 0 min) and yawning monitored from -15 to +60 min by recording displacement of the lower jaw and storing the traces on diskettes. After placebo, the number of yawns was 5.3 +/- 1.4 (means +/- SE) and after scopolamine pretreatment 4.3 +/- 1.6 (p = NS). Drowsiness was assessed with the Stanford Sleepiness Scale and the Analog Sleepiness Scale at -15, 0, +20, +40, +60 min. There was no significant correlation between total sleepiness scores (area under the curve, 0 min to +60 min), peak sleepiness score or peak increment in sleepiness score and number of yawns on either scale. These data suggest that (a) spontaneous yawning in man is not mediated by a central muscarinic cholinergic link, and (b) the assumed relationship between drowsiness and yawning remains to be verified experimentally.

Adult↗
PubMed1993

High-dose combined alkylating agent therapy with autologous stem cell support and chest radiotherapy for limited small-cell lung cancer.

Although initially responsive to chemotherapy, patients with small-cell lung cancer (SCLC) almost invariably suffer relapse. Recurrent SCLC responds poorly to treatment. Previous trials using high-dose chemotherapy with bone marrow support have commonly used single agents or combined alkylating agents without chest radiotherapy. Among patients with limited disease receiving dose-intensive chemotherapy, locoregional relapse remained the predominant site of first failure. Recent phase II trials using intensive locoregional therapy (aggressive concurrent chemoradiotherapy) have resulted in promising survival. Our trial used combined alkylating agents with autologous marrow support and chest radiotherapy in patients with limited disease in response to conventional-dose induction chemotherapy. Of 19 patients treated, the actuarial survival was 56% with a median follow-up of 18 months following high-dose therapy. Patients who achieved complete or near-complete response prior to high-dose therapy enjoyed the best prognosis. Continued evaluation of intensive systemic and local therapy for SCLC is indicated.

Alkylating Agents↗
PubMed1992

Mobilization of peripheral blood progenitor cells by chemotherapy and granulocyte-macrophage colony-stimulating factor for hematologic support after high-dose intensification for breast cancer.

High-dose therapy with autologous marrow support results in durable complete remissions in selected patients with relapsed lymphoma and leukemia who cannot be cured with conventional dose therapy. However, substantial morbidity and mortality result from the 3- to 6-week period of marrow aplasia until the reinfused marrow recovers adequate hematopoietic function. Hematopoietic growth factors, particularly used after chemotherapy, can increase the number of peripheral blood progenitor cells (PBPCs) present in systemic circulation. The reinfusion of PBPCs with marrow has recently been reported to reduce the time to recovery of adequate marrow function. This study was designed to determine whether granulocyte-macrophage colony-stimulating factor (GM-CSF)-mobilized PBPCs alone (without marrow) would result in rapid and reliable hematopoietic reconstitution. Sixteen patients with metastatic breast cancer were treated with four cycles of doxorubicin, 5-fluorouracil, and methotrexate (AFM induction). Patients responding after the first two cycles were administered GM-CSF after the third and fourth cycles to recruit PBPCs for collection by two leukapheresis per cycle. These PBPCs were reinfused as the sole source of hematopoietic support after high doses of cyclophosphamide, thiotepa, and carboplatin. No marrow or hematopoietic cytokines were used after progenitor cell reinfusion. Granulocytes greater than or equal to 500/microL was observed on a median of day 14 (range, 8 to 57). Transfusion independence of platelets greater than or equal to 20,000/microL occurred on a median day of 12 (range, 8 to 134). However, three patients required the use of a reserve marrow for slow platelet engraftment. In retrospect, these patients were characterized by poor baseline bone marrow cellularity and poor platelet recovery after AFM induction therapy. When compared with 29 historical control patients who had received the same high-dose intensification chemotherapy using autologous marrow support, time to engraftment, antibiotic days, transfusion requirements, and lengths of hospital stay were all significantly improved for the patients receiving PBPCs. Thus, autologous PBPCs can be efficiently collected during mobilization by chemotherapy and GM-CSF and are an attractive alternative to marrow for hematopoietic support after high-dose therapy. The enhanced speed of recovery may reduce the morbidity, mortality, and cost of high-dose treatment. Furthermore, PBPC support may enhance the effectiveness of high-dose therapy by facilitating multiple courses of therapy.

Adolescent↗
PubMed1992

A defective splice site at the phenylalanine hydroxylase gene in phenylketonuria and benign hyperphenylalaninemia among Palestinian Arabs.

Phenylketonuria (PKU) and benign hyperphenylalaninemia (HPA) result from different combinations of mutations at the locus for phenylalanine hydroxylase (PAH). While some of these mutations show widespread ethnic distribution, others are unique to specific communities. We report here the first point mutation common among Palestinian Arabs. The mutation (IVS2nt1) involves a dinucleotide substitution (Gg-->Aa) at the donor splice site of intron 2 of the PAH gene and abolishes a recognition site of the restriction enzyme MnlI. IVS2nt1 is associated with two PAH polymorphic haplotypes, 7 and 42. Homozygotes for this mutation are affected with severe, classical PKU. Compound heterozygotes carrying the IVS2nt1 allele and one of several other yet unknown mutations show different degrees of benign HPA.

Base Sequence↗
PubMed1992

Serum and mononuclear cell potassium, magnesium, sodium and calcium in pregnancy and labour and their relation to uterine muscle contraction.

Thirty women in their third trimester of pregnancy (37-42 weeks), 40 women during and 72 h after labour and 18 non-pregnant controls were studied for changes in serum and mononuclear cell cation content, and their relationship to cervical effacement and intensity of pain as measured by plasma beta endorphin concentrations during labour. Serum magnesium fell from 0.95 +/- 0.01 (mean +/- SEM) to 0.84 +/- 0.02 mmol/litre at late pregnancy and further to 0.76 +/- 0.01 during labour (P < 0.001); serum potassium fell from 4.25 +/- 0.05 to 3.79 +/- 0.06 mmol/litre (P < 0.0001) during labour; and serum calcium fell from 2.40 +/- 0.02 to 2.28 +/- 0.01 mmol/litre at late pregnancy (P < 0.001) and further to 2.25 +/- 0.02 mmol/litre during labour (P < 0.001). Mononuclear cell magnesium content rose from 4.5 +/- 0.3 to 5.6 +/- 0.04 fmol/cell (P < 0.02); potassium content rose from 37.7 +/- 2.0 to 50.9 +/- 3.0 fmol/cell (P < 0.001); and calcium content rose from 4.4 +/- 0.4 to 7.6 +/- 1.1 fmol/cell (P < 0.105). On the other hand, mononuclear cell sodium content fell from 7.2 +/- 0.5 to 3.8 +/- 0.3 fmol/cell (P < 0.001). Plasma beta endorphin concentrations increased with increasing degrees of effacement, as did intracellular Na, whereas intracellular Mg and K showed an inverse trend. A significant correlation was found between intracellular cation and beta endorphin levels (r = -0.98, Mg; -0.99, K; 0.83, Na). These changes are probably due either to intercompartmental cation shifts or possibly to endometrial ischaemia and damage during labour.

Adolescent↗
PubMed1991

Combined chemical and mechanical effects on free radicals in UHMWPE joints during implantation.

An electron spin resonance (ESR) technique is employed to determine the free radical distribution in the articulating surfaces of retrieved acetabular cups and knee-joint plateaus (retrieved after more than 6 years of implantation). Similar measurements made on samples prepared from cyclically stressed and unstressed cups, and on samples following oxidations in nitric acid and intralipid solutions provided sufficient data to gain more knowledge about the combined chemical and mechanical effects on PE free radicals during implantation. In UHMWPE free radicals are primarily initiated by gamma-ray sterilization; however, during implantation, peroxy (scission type) free radicals are formed and reach a maximum concentration level (equilibrium state) due to oxidation by chemical (hemoglobin and/or synovial fluids) environment of the joints. Subsequently, due to frictional heating and stress in the loading zones, free radical reaction is accelerated and their number is reduced only in those areas. This is consistent with the observations of a temperature rise in acetabular cups during in vitro frictional wear stress tests and in vivo telemetry observations, as reported by others. Compared with the previously reported SEM micrographs the low-free-radical regions are correlated with high-wear areas and the high-free-radical regions with the low-wear areas.

Biocompatible Materials↗
PubMed1991

GM-CSF potentiated peripheral blood progenitor cell (PBPC) collection with or without bone marrow as hematologic support of high-dose chemotherapy: two protocols.

High-dose chemotherapy with autologous bone marrow support (ABMS) achieves prolonged relapse-free survival in relapsed lymphomas and leukemias and has provided durable complete responses in certain solid tumors. The principal morbidity and mortality result from the infectious and bleeding complications during the 3-4 week aplasia until the bone marrow autograft can recover. Hematopoietic growth factors, alone or used after chemotherapy, increase the number of circulating progenitor cells in the peripheral blood compartment. In one trial, 12 patients with solid tumors were treated with high-dose chemotherapy and supported with both bone marrow and peripheral blood progenitor cells (PBPC) collected after GM-CSF administration. Reconstitution of bone marrow function occurred quickly (ANC greater than 500/microliters by day 17; platelet-transfusion independence by day 16), resulting in short hospital stays (median, 28 days). In a second study, 12 patients with metastatic breast cancer responding to induction chemotherapy (doxorubicin, 5-fluorouracil, and methotrexate) were given GM-CSF during induction to collect PBPCs during leukocyte recovery. These PBPCs were used as the sole hematopoietic support during high-dose chemotherapy with cyclophosphamide, thiotepa, and carboplatin. Granulocyte and platelet reconstitution were extremely rapid (median, 14 and 12 days, respectively). When compared with 29 patients undergoing the same intensification therapy using ABMT as sole support, time to hematopoietic recovery, transfusion requirements, and duration of hospital stay were all significantly improved for the patients receiving PBPC. PBPC with or without marrow may enhance the safety, tolerance, and cost of high-dose therapy. Moreover, PBPC may render multiple course combination, high-dose therapy feasible.

Antineoplastic Combined Chemotherapy Protocols↗