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Biomedical subjects

L Weiner

Publications and source records attributed to L Weiner.

At least 19 recordsLinked to original sources
PubMed1992

The application of pH-sensitive spin labels to studies of surface potential and polarity of phospholipid membranes and proteins.

The effects of pH titration on the EPR spectra of imidazolidine nitroxides located at the surface of mixed bilayers composed of dimyristoylphosphatidylglycerol (DMPG) and dimyristoylphosphatidylcholine (DMPC), and at the surface of the protein, human serum albumin (HSA), have been investigated. It is found that the shift in pKa of the amino group of the imidazolidine radical from its value of 4.6 in water depends both on the interfacial polarity (delta pKapol) and on the electrostatic surface potential (delta pKael) when it is positioned at the bilayer/water interface by an anchoring hydrocarbon tail. The polarity shift is determined to be: delta pKapol = -1.3 units at the surface of DMPC bilayers at 17 degrees C, corresponding to an effective interfacial dielectric constant of epsilon approximately 37, and depends on the temperature with a coefficient of d delta pKapol/dT approximately -0.01 per degree. The electrostatic shift at the surface of DMPG bilayers is delta pKael = +1.6 units in 0.1 M KCl, which corresponds to an electrostatic surface potential of -95 mV. This electrostatic shift depends strongly both on ionic strength and on the fraction of charged lipid in the DMPC/DMPG mixtures, in a manner that agrees with the predictions of electrostatic double-layer theory. It is found that the shift in pKa of an imidazolidine radical covalently bound at the surface of HSA is determined mainly by the surface electrostatics (delta pKapol approximately 0) and corresponds to an electrostatic potential of +33 mV in 0.01 M KCl at a pH below the isoelectric point of the protein.

Dimyristoylphosphatidylcholine↗
PubMed1992

Pediatricians' perspectives on fetal alcohol syndrome.

Since the identification of fetal alcohol syndrome (FAS) in 1973, significant inroads have been made towards understanding the effects of alcohol on fetal development. However, it is not clear if these findings are considered clinically relevant by pediatricians. This survey was designed to assess clinical knowledge, practice, and attitudes concerning alcohol-related birth defects. Data were collected in a questionnaire that was mailed to 234 randomly selected Massachusetts pediatricians. Responses suggest that a substantial proportion of pediatricians have knowledge about the effects of alcohol on pregnancy. However, many considered themselves unprepared to deal with this topic. More physicians suspected FAS/FAE than made the diagnosis. Almost three fourths reported they would find professional education in this area helpful. Broader dissemination of research findings in clinically relevant formats and improving the sense of preparedness among pediatricians have the potential to improve the care of children born to heavily drinking pregnant women.

Attitude of Health Personnel↗
PubMed1991

Characterization and sequence of the Escherichia coli stress-induced psp operon.

We describe a new Escherichia coli operon, the phage shock protein (psp) operon, which is induced in response to heat, ethanol, osmotic shock and infection by filamentous bacteriophages. The operon includes at least four genes: pspA, B, C and E. PspA associates with the inner membrane and has the heptad repeats characteristic of proteins that can form coiled coils. The operon encodes a factor that activates psp expression, and deletion analyses indicate that this protein is PspC; PspC is predicted to possess a leucine zipper, a motif present in many eukaryotic transcription factors. The pspE gene is expressed in response to stress as part of the operon, but is also transcribed from its own promoter under normal conditions. In vitro studies suggest that PspA and C are modified in vivo. Expression of the psp genes does not require the heat shock sigma factor, sigma32. The increased duration of psp induction in a sigma32 mutant suggests that a product (or products) of the heat shock response down-regulates expression of the operon.

Amino Acid Sequence↗
PubMed1991

Antierythrocyte autoantibody formation after therapy with interleukin-2 and gamma-interferon.

The cardiovascular, renal, pulmonary, and dermatologic toxicities of interleukin-2 (IL-2) and gamma-interferon (IFN) are well described. However, autoimmune toxicities have only recently been noticed. The authors report the development of warm autoantibodies against erythrocytes in a patient receiving IL-2 (3.75 x 10(6) cetus units/m2 intravenous bolus three times per week) and gamma-IFN (0.1 mg/m2 subcutaneously three times per week) for metastatic renal cell carcinoma. Other potential causes of autoantibody formation, such as drugs, infection, and collagen vascular disease, were excluded. Both gamma-IFN and IL-2 have the potential to trigger or exacerbate autoimmunity due to either aberrant expression of restricted antigens or inhibition of normal cellular immune suppressor mechanisms.

Autoantibodies↗
PubMed1991

Stress-induced expression of the Escherichia coli phage shock protein operon is dependent on sigma 54 and modulated by positive and negative feedback mechanisms.

The phage shock protein (psp) operon of Escherichia coli is strongly induced in response to heat, ethanol, osmotic shock, and infection by filamentous bacteriophages. The operon contains at least four genes--pspA, pspB, pspC, and pspE--and is regulated at the transcriptional level. We report here that psp expression is controlled by a network of positive and negative regulatory factors and that transcription in response to all inducing agents is directed by the sigma-factor sigma 54. Negative regulation is mediated by both PspA and the sigma 32-dependent heat shock proteins. The PspB and PspC proteins cooperatively activate expression, possibly by antagonizing the PspA-controlled repression. The strength of this activation is determined primarily by the concentration of PspC, whereas PspB enhances but is not absolutely essential for PspC-dependent expression. PspC is predicted to contain a leucine zipper, a motif responsible for the dimerization of many eukaryotic transcriptional activators. PspB and PspC, though not necessary for psp expression during heat shock, are required for the strong psp response to phage infection, osmotic shock, and ethanol treatment. The psp operon thus represents a third category of transcriptional control mechanisms, in addition to the sigma 32- and sigma E-dependent systems, for genes induced by heat and other stresses.

Bacterial Proteins↗
PubMed1991

Effects of early tangential excision and grafting on survival after burn injury.

This report quantifies the increase of burn survival, which we believe is associated with the use of early tangential excision and grafting as opposed to conventional therapy in adult patients with burns. To quantify the increase, we compared the lethal area 50 of various age groups with that of previous historical studies that used other techniques. These data suggest that early excision and grafting are associated with a marked improvement in survival in patients 41 to 60 years of age with 20 to 65 per cent total body surface area burns.

Adult↗
PubMed1990

Interferon gamma increases in vitro and in vivo expression of C1 inhibitor.

C1 inhibitor (C1 INH) is the major protease inhibitor of the first components of the classic complement system and of the proteases of the Hageman factor pathways. Since C1 INH may modulate inflammatory reactions associated with complement and contact system activation, we sought to determine if the cytokine gamma interferon (IFN-gamma) could modulate C1 INH production. Initial studies investigated the effect of IFN-gamma on the molecular and protein expression of C1 INH in human erythroleukemia (HEL) cells. HEL cells constitutively expressed the 2.1 kb mRNA for C1 INH. IFN-gamma (50 to 1,000 U/mL), but not interferon alpha or beta, increased twofold the amount of C1 INH mRNA expressed within HEL cells. Similarly, this cytokine increased HEL cell C1 INH synthesis of a 105 Kd protein 10-fold, from 1.9 +/- 0.5 microgram C1 INH antigen per 10(8) cells (mean +/- SEM) to 19 +/- 8 micrograms/10(8) cells in 8 days. C1 INH produced by HEL cells after IFN-gamma stimulation had fully intact kallikrein neutralizing activity. Moreover, conditioned media of IFN-gamma-treated HEL cells accumulated more secreted C1 INH in 8 days (6.7 micrograms/mL/10(8) cells) than untreated cells (0.6 microgram/mL/10(8) cells). Additional studies were done on plasma specimens from 22 patients with metastatic colorectal carcinoma who received IFN-gamma daily for 4 days by intravenous infusion. Before treatment, the mean +/- SEM C1 INH levels in these patients was 438 +/- 16 micrograms/mL. At day 10 from the start of the infusion, the plasma C1 INH in these patients increased to 586 +/- 32 micrograms/mL (P less than .0001). The extent of rise of plasma C1 INH after IFN-gamma treatment was independent of dose from 0.01 to 40 U/m2. After 30 days, the mean plasma C1 INH levels decreased to 502 +/- 27 micrograms/mL. These combined studies indicate that IFN-gamma can increase C1 INH protein expression in vitro and in vivo.

Blotting, Northern↗
PubMed1990

Lead exposure among mothers and their newborns in Toronto.

Recent studies have suggested that a fetal blood lead level of 0.48 mumol/L (much lower than 1.21 mumol/L, which is the level previously believed to be toxic to the developing brain) may impair brain development permanently. We measured the maternal and umbilical cord blood levels of lead and free erythrocyte protoporphyrin (FEP) among 95 consecutive mother-infant pairs to determine whether neonates in Toronto are in the high-risk group. There was a significant correlation between the maternal and the cord blood lead levels (r = 0.59, p less than 0.0001). Most (99%) of the infants had cord blood lead levels below 0.34 mumol/L; in 11 cases the levels were below the detection limit of 0.01 mumol/L. The cord blood FEP levels were higher than the maternal levels. The US Centers for Disease Control, Atlanta, currently finds acceptable a blood FEP level of 0.62 mumol/L among children up to 10 years of age; however, this is not applicable to newborns since their higher FEP levels apparently reflect immature heme synthesis and increased erythrocyte volume rather than lead poisoning. Our data suggest that living in Toronto does not impose increased teratogenic risk from intrauterine exposure to lead; however, residents in high-risk areas should be followed up.

Adult↗
PubMed1990

Phage shock protein, a stress protein of Escherichia coli.

Filamentous phage infection induces the synthesis of large amounts of an Escherichia coli protein, phage shock protein (Psp), the product of a previously undescribed gene. This induction is due to the phage gene IV protein, pIV, an integral membrane protein. The uninduced level of Psp is undetectable, but when induced by prolonged synthesis of pIV, it can become one of the most abundant proteins in the cell. Psp is also synthesized transiently in response to several stresses (heat, ethanol, and osmotic shock). High-level synthesis occurs only after extreme treatment. Unlike the members of the heat shock regulon, Psp induction does not require the heat shock sigma factor, sigma 32; some stimuli that elicit sigma 32-dependent heat shock proteins do not induce Psp synthesis. The level of Psp induction after extreme stress is even higher in sigma 32 mutant cells, which are unable to mount a normal heat shock response, suggesting that these parallel stress responses are interrelated.

Bacterial Proteins↗
PubMed1989

Cadralazine challenge in patients with previous hydralazine-induced lupus: a 6-month study.

The objective of this study was to investigate the effect of cadralazine in patients who had previously had hydralazine-induced lupus. There were 11 patients included in the study, 10 of whom were treated for 6 months with 15 or 20 mg cadralazine given once daily in combination with beta-blockers and diuretics. All patients had a history of hydralazine-induced lupus and were slow acetylators. None of the patients included in this study showed any current signs or symptoms of drug-induced lupus. No evidence of lupus-like symptoms or of immunologic laboratory abnormalities were found during the study period. Side effects associated with vasodilator therapy were noted in some patients but were transient and mild. We concluded that a cross-reaction between cadralazine and hydralazine does not seem likely to occur and that cadralazine, because of its chemical properties, probably will not give rise to drug-induced lupus.

Acetylation↗
PubMed1989

FAS/FAE: focusing prevention on women at risk.

Consumption of alcohol during pregnancy is well recognized as a risk factor associated with adverse fetal development. While precise safe or dangerous levels of maternal drinking have not been identified, it is clear that the women who drink most heavily are at the greatest risk. Prevention of alcohol-related birth defects requires development of programs directed to the special needs of addicted women and their families. The nature of addiction suggests that direct interventions focused on changing individual drinking behavior have the best chance of success.

Alcoholism↗
PubMed1988

Extranodal non-T-cell lymphoblastic lymphoma in adults. A report of two cases.

Typical adult cases of malignant lymphoma, diffuse, lymphoblastic type (MLLB), are of the T-cell immunophenotype and occur as mediastinal masses. The authors report two unusual adult cases with initial extranodal sites of involvement and non-T-cell immunophenotype that were originally misclassified. One patient presented with a right submaxillary salivary gland mass and the other presented with a T7-8 spinal cord compression resulting from a vertebral body tumor. A lymphoblastic leukemic phase developed in both patients after 15 months and 5 months, respectively. The bone marrow blasts of both patients had positive results for cluster designation (CD) 10, CD19, HLA-DR, and terminal deoxynucleotidyl transferase. Because both extranodal sites of presentation and non-T-cell immunophenotype are unusual in adult MLLB, these features may have contributed to the original misclassification of these lesions.

Adult↗
PubMed1987

Effects of bisoprolol on blood pressure, serum lipids and HDL-cholesterol in essential hypertension.

Fifty patients with essential hypertension WHO Grades I-II have been treated for 3 months with bisoprolol, a new selective beta blocker, in doses up to 40 mg once daily. Forty-three patients reached the preset target diastolic blood pressure of less than or equal to 90 mmHg on a mean daily dose of 16.8 mg bisoprolol. There was no effect on serum lipids and HDL-cholesterol during the study. The side-effects were mild and were those usually associated with beta-blocking therapy.

Adrenergic beta-Antagonists↗
PubMed1987

Efficacy and safety of bisoprolol and atenolol in patients with mild to moderate hypertension: a double-blind, parallel group international multicentre study.

Three hundred and fifteen patients were randomly allocated to treatment for six months with bisoprolol 5 or 10 mg day-1 or atenolol, 50 mg day-1, in a double-blind, double-dummy parallel group, international multicentre study. Two hundred and ninety-two (175 men and 117 women) were eligible for statistical follow-up. Their mean age was 52.6 years (range 28-70). All patients had a supine diastolic blood pressure of 95-120 mmHg on two occasions during the four weeks of placebo treatment. Twenty-four patients ended the study prematurely and a further 19 had their regimes changed because of an insufficient effect. The reasons for drop-out were similar in the three treatment groups. Thus, 249 patients continued to receive the treatment they were allocated to, with 80, 83 and 86 patients in the three respective groups. The sex and age distributions and the number of previously treated hypertensives were similar in the three groups. At the end of placebo treatment the supine blood pressures in the three groups (bisoprolol 5 or 10 mg day-1 or atenolol 50 mg day-1, respectively) were 163.9/102.5, 157.4/101.8 and 160.0/102.2 mmHg, respectively. The systolic blood pressure was higher (P less than 0.05) in the group receiving bisoprolol 5 mg day-1 than in the 10 mg day-1 group. After 26 weeks of treatment the supine blood pressures in the three groups were 150.6/90.8, 142.0/89.1 and 148.6/91.7 mmHg, respectively. The largest estimated difference in blood pressure reduction was 4.6/2.3 mmHg between the group receiving bisoprolol 10 mg day-1 and the group receiving atenolol 50 mg day-1. A reduction in mean blood pressure of greater than or equal to 10 mmHg was noted in 66% of the patients in the bisoprolol group (10 mg day-1), in the other groups 66 and 59%, n.s. Bisoprolol is effective, well-tolerated and safe in the treatment of hypertension. A daily dose of 5 mg seems recommendable for the majority of hypertensive patients and seems equipotent with 50 mg day-1 of atenolol in the present study.

Adult↗