Search PubMed⌕ Search

Biomedical subjects

E Friedman

Publications and source records attributed to E Friedman.

At least 181 records · Page 10Linked to original sources
PubMed1997

Heterologous desensitization of the rat tail artery contraction and inositol phosphate accumulation after in vitro exposure to phenylephrine is mediated by decreased levels of Galphaq and Galphai.

Desensitization of alpha-1 adrenoceptor (alpha1AR)-mediated responses in aortic smooth muscle after exposure to catecholamines or alpha1AR agonists has been widely demonstrated. To determine whether exposure to an alpha1AR agonist results in desensitization of alpha1AR-mediated responses in a resistance artery, rat tail artery rings were exposed to 7.5 or 75 microM phenylephrine (PE) for 22 hr in vitro. Norepinephrine-stimulated contraction was significantly reduced in PE-exposed tail artery rings. Contractions mediated by the alpha2AR agonists, clonidine and UK 14,304, and by serotonin were also reduced in PE-treated tail artery rings. However, the contractile responses to KCl and ionomycin remained unchanged. Norepinephrine-, PE-, endothelin- and serotonin-stimulated inositol phosphate accumulations were reduced in PE-exposed tail artery rings, whereas KCl- and ionomycin-stimulated inositol phosphate accumulation remained unchanged. The density of membrane alpha1ARs, measured by specific [125I]2-([beta-(4-hydroxyphenyl)ethyl]aminomethyl)-1-etralone binding was not changed in PE-desensitized tail arteries. Further studies were performed to examine if alterations in receptor/G protein interaction accompanies arterial desensitization. In these studies receptor-stimulated increases in [35S]GTPgammaS binding to G proteins was assessed in membranes obtained from vehicle (control) and PE-treated tail arteries. In control membranes alpha1AR stimulation increased [35S]GTPgammaS binding to Galphaq and Galphai proteins, whereas the alpha2AR agonist UK14,304 activated [35S]GTPgammaS binding to Galphai exclusively. Both PE- and UK14, 304-induced responses were reduced in membranes from tail arteries that were exposed to either 7.5 or 75 microM PE for 22 hr. Western blot analyses of G protein alpha and beta subunits demonstrated that Galphaq and Galphai protein levels were decreased in PE-exposed tail artery membranes. These data show that the reduced transmembrane signaling for the alpha1AR in tail artery after in vitro PE exposure is associated with decreases in Galphaq and Galphai protein levels. The reduction in these Galpha proteins also appears to mediate the loss of function of alpha2AR and perhaps of other G protein-coupled receptors.

Adrenergic alpha-Agonists↗
PubMed1997

Reduced adenosine A1 receptor and G alpha protein coupling in rat ventricular myocardium during aging.

Adenosine A1 receptor (A1-AdoR) function in rat ventricles has previously been shown to decrease with age. In the present study, using the ligand [3H]8-cyclopentyl-1,3-dipropylxanthine ([3H]DPCPX) and coimmunoprecipitation of A1-AdoRs with their associated G proteins, we determined the specific binding of A1-AdoR and A1-AdoR/G protein coupling in ventricular myocardium of 6- to 24-month-old Fischer 344 rats. The densities (Bmax) of A1-AdoRs were 5.8 +/- 0.8 fmol/mg protein in 6-month-old rats and 6.1 +/- 1.4 fmol/mg protein in 24-month-old rats, and the dissociation constants (Kd) were 0.32 +/- 0.04 nmol/L in 6-month-old rats and 0.34 +/- 0.05 nmol/L in 24-month-old rats (P > .05). Analysis of the dose-dependent displacement of [3H]DPCPX binding by the selective A1-receptor agonist, N6-p-sulfophenyladenosine (SPA), yielded two affinity binding sites in both 6- and 24-month-old rats. However, the proportion of high-affinity A1-AdoRs was significantly lower in 24-month-old rats (23.5%) compared with 6-month-old rats (54.9%) (P < .05). In solubilized ventricular membranes, specific [3H]DPCPX binding sites were detected in immunoprecipitates of G alpha i3 and G alpha o antisera but not with antibodies for other G alpha proteins. The basal coimmunoprecipitation of A1-AdoR with G alpha i3 and G alpha o proteins decreased by 22% and 21%, respectively, in ventricular membranes of 24-month-old rats compared with that in 6-month-old animals. A1-AdoR stimulation with SPA increased the coprecipitation of A1-AdoR with G alpha i3 and G alpha o proteins by 287% and 245%, respectively, in 6-month-old rats but only by 129% and 140%, respectively, in 24-month-old rats (P < .01). In the absence of changes in A1-AdoR density and G alpha protein levels, an age-related decline in high-affinity A1-AdoR binding sites and a reduction in the association of A1-AdoR with G alpha proteins suggest that the age-related decrease in ventricular A1-AdoR-mediated response is related to a reduction in the coupling between A1-AdoR and their G proteins.

Adenylyl Cyclase Inhibitors↗
PubMed1997

A hidden complication of out-patient arteriography.

Rapid progression of arterial disease may occur between out-patient diagnostic arteriography and therapeutic angioplasty. We have studied the incidence of this complication in our institution. Sixty-seven consecutive out-patient arteriograms were assessed. Thirty-four patients were re-admitted for angioplasty within a median interval of 4 weeks (range 5 days-3 months). We compared immediate pre-angioplasty arteriograms with the out-patient images. Twenty-five pairs of films showed disease progression. Three patients showed new disease, one remote from the site of the arterial lesion and two in the opposite limb. Six patients showed marked progression of the original disease. The policy of delayed treatment after out-patient arteriography may require reconsideration in the light of our complication rate of 18%.

Aged↗
PubMed1996

High frequency of BRCA1 185delAG mutation in ovarian cancer in Israel. National Israel Study of Ovarian Cancer.

OBJECTIVE: To determine the role of BRCA1 185delAG mutation in ovarian carcinogenesis. DESIGN: Genetic testing of a subset of cases from an ongoing study of ovarian cancer and of controls. SETTING: A community-based case-control incidence study. SUBJECTS: Seventy-nine patients with ovarian cancer, 62 hospitalized women without cancer (controls), and 120 healthy women participating in a fragile X screening program (also controls), examined for the presence of germline BRCA1 185delAG mutation. MAIN OUTCOME MEASURES: Polymerase chain reaction-amplified BRCA1 exon 2 fragments generated from patients' and controls' blood samples, analyzed by heteroduplex gel shift assay and direct sequence analyses. RESULTS: The 185delAG mutation was detected in 38.9% (7/18) of ovarian cancer patients with familial history, and 13.1% (8/61) of family history-negative ovarian cancer cases. Only 1 carrier was detected among the 120 healthy controls, and none in the hospital controls. A significant difference in mutation carrier rates between family history-negative cases and control groups of 120 and 62 subjects was identified (Fisher exact test, P=.001 and P=.003, respectively). The median age (+/-SE) at disease diagnosis was lower among both familial and family history-negative mutation carriers, as compared with mutation-negative, family history-negative cases--50 (+/-1.4) vs 60.5 (+/-3.5) years old, respectively (hazard ratio, 1.68; 95% confidence interval, 0.94-3.01). CONCLUSIONS: Our data are preliminary but suggest that BRCA1 185delAG germline mutation is frequent in Israeli ovarian cancer patients, irrespective of family history, and may confer an early-onset phenotype of ovarian cancer

BRCA1 Protein↗
PubMed1996

Impaired learning in mice with abnormal short-lived plasticity.

BACKGROUND: Many studies suggest that long term potentiation (LTP) has a role in learning and memory. In contrast, little is known about the function of short-lived plasticity (SLP). Modeling results suggested that SLP could be responsible for temporary memory storage, as in working memory, or that it may be involved in processing information regarding the timing of events. These models predict that abnormalities in SLP should lead to learning deficits. We tested this prediction in four lines of mutant mice with abnormal SLP, but apparently normal LTP-mice heterozygous for a alpha-calcium calmodulin kinase II mutation (alpha CaMKII +/-) have lower paired-pulse facilitation (PPF) and increased post-tetanic potentiation (PTP); mice lacking synapsin II (SyII-/-), and mice defective in both synapsin I and synapsin II (SyI/II-/-), show normal PPF but lower PTP; in contrast, mice just lacking synapsin I (SyI-/-) have increased PPF, but normal PTP. RESULTS: Our behavioral results demonstrate that alpha CaMKII +/-, SyII-/- and SyI/II-/- mutant mice, which have decreased PPF or PTP, have profound impairments in learning tasks. In contrast, behavioral analysis did not reveal learning deficits in SyI-/- mice, which have increased PPF. CONCLUSIONS: Our results are consistent with models that propose a role for SLP in learning, as mice with decreased PPF or PTP, in the absence of known LTP deficits, also show profound learning impairments. Importantly, analysis of the SyI-/- mutants demonstrated that an increase in PPF does not disrupt learning.

Animals↗
PubMed1996

Enhanced protein kinase C activity and translocation in bipolar affective disorder brains.

Protein kinase C (PKC) activity and its redistribution were determined in the frontal cortices of postmortem brains of bipolar affective disorder subjects and age-, sex-, and postmortem time-matched controls. Membrane and cytosolic PKC activity was determined by histone phosphorylation using [32P]-adenosine triphosphate as substrate. Specific PKC isozyme levels were assessed by Western blot analysis using antipeptide antibodies. Brain membrane-associated PKC activity was higher in bipolar vs. control tissue. An examination of the specific PKC isozymes in cortical homogenates revealed that cytosolic alpha- and membrane-associated gamma- and zeta PKC isozymes were elevated in cortices of bipolar affective disorder subjects, whereas cytosolic epsilon PKC was found to be reduced. In control brain slices, incubation with 1 mumol/L phorbol 12-myristate 13-acetate (PMA) caused an increase in membrane PKC activity, whereas cytosolic enzyme activity was decreased. This redistribution of the enzyme by PMA was markedly potentiated in brain slices of bipolar subjects. The results suggest that PKC-mediated phosphorylation is increased in brains of subjects with bipolar affective illness.

Adult↗
PubMed1996

Genomic responses to 5-HT1A or 5-HT2A/2C receptor activation is differentially regulated in four regions of rat brain.

The functional profiles of brain 5-HT1A and 5-HT2A/C receptors were assessed by quantitating changes in the immediate early genes -c-fos, ngf1c and tis1, following receptor activation with either 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin) or DOI (1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane). Stimulation of either class of 5-HT receptor elicited an induction of all three immediate early genes to varying extents in cortex, hippocampus and cerebellum, but not in striatum. The responses to 8-OH-DPAT peaked earlier than those to DOI. WAY 100135 (N-tertiobutyl-3-[4-(2-methoxyphenyl)-piperazinyl]-2-phenylpropana mide), the putative 5-HT1A receptor antagonist blocked the 8-OH-DPAT effect but not the responses to DOI. WAY 100135 by itself also elicited a relatively smaller genomic response. Ketanserin completely abolished the DOI-induced genomic responses. The results support the earlier findings that 5-HT1A receptor sites are abundant in frontal cortex and hippocampus. In addition, the robust genomic responses to 8-OH-DPAT as well as Northern hybridization with a cDNA probe for 5-HT1A mRNA in the cerebellum clearly implicate the functional expression of 5-HT1A receptors in this brain region. The responses to the 5-HT2 receptor agonist, DOI support a greater abundance of these receptors in the cortex, and relatively lower levels in hippocampus and cerebellum. The results suggest a differential induction pattern among the three immediate-early genes depending on the brain region and the 5-HT receptor subtype involved.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1996

Increased expression of protein kinase C beta activates ERK3.

In a prior study, we have shown that stable transfection of expression plasmids for protein kinases C beta 1 (PKC beta 1) or PKC beta 2 into differentiated colon cancer cells led to elevated levels of PKC beta 1 or PKC beta 2 protein and PKC beta kinase activities in the transfectants, without altering PKC alpha levels. PKC gamma is not found in these cells, so the major modulation was in PKC beta. PKC beta transfectant cells exhibited blocked differentiation, increased growth rate in athymic mice, and restoration of the basic fibroblast growth factor response pathway. In this study, we have extended the analysis of these PKC beta transfectants to the mitogen-activated protein kinase ERK3. Analysis of cell lysates on the mitogen-activated protein kinase substrate myelin basic protein by in gel kinase assay showed increased activity at 63 kDa, the size of ERK3, in each of two PKC beta 1 and each of two PKC beta 2 transfectants compared with the vector control transfectant. ERK3 was expressed at equal abundance in PKC beta 1, PKC beta 2, and control transfectant cells as demonstrated by Western blotting and by immunoprecipitation with anti-ERK3 monoclonal antibody. However, a > 10-fold increase in ERK3 activity in each PKC beta transfectant was shown by immunoprecipitation with anti-ERK3 monoclonal antibody followed by either immune complex kinase assay or by in gel kinase assay. Thus, while overexpression of transfected PKC beta does not lead to overexpression of ERK3, it does lead to constitutive activation of ERK3. A causal link between PKC beta overexpression and ERK3 activation was established because 12-O-tetradecanoylphorbol-13-acetate treatment down-regulated both PKC and ERK3 activities in both PKC beta 1 transfectants. ERK3 activity was found in nuclear and membrane fractions in each PKC beta transfectant, in contrast to controls, perhaps accounting for constitutive activation of ERK3 in cells with elevated levels of PKC beta 1 or PKC beta 2.

Animals↗
PubMed1996

Multi-disciplinary clinical study of Smith-Magenis syndrome (deletion 17p11.2)

Smith-Magenis syndrome (SMS) is a multiple congenital anomaly, mental retardation (MCA/MR) syndrome associated with deletion of chromosome 17 band p11.2. As part of a multi-disciplinary clinical, cytogenetic, and molecular approach to SMS, detailed clinical studies including radiographic, neurologic, developmental, ophthalmologic, otolaryngologic, and audiologic evaluations were performed on 27 SMS patients. Significant findings include otolaryngologic abnormalities in 94%, eye abnormalities in 85%, sleep abnormalities (especially reduced REM sleep) in 75%, hearing impairment in 68% (approximately 65% conductive and 35% sensorineural), scoliosis in 65%, brain abnormalities (predominantly ventriculomegaly) in 52%, cardiac abnormalities in at least 37%, renal anomalies (especially duplication of the collecting system) in 35%, low thyroxine levels in 29%, low immunoglobulin levels in 23%, and forearm abnormalities in 16%. The measured IQ ranged between 20-78, most patients falling in the moderate range of mental retardation at 40-54, although several patients scored in the mild or borderline range. The frequency of these many abnormalities in SMS suggests that patients should be evaluated thoroughly for associated complications both at the time of diagnosis and at least annually thereafter.

Abnormalities, Multiple↗
PubMed1996

Dopamine-stimulated changes in activated calpain I in rat hippocampal slices.

Activated calpain I immunoreactivity (76 kDa band) was detected in membranes prepared from rat brain hippocampal slices using a polyclonal antiserum raised against an N-terminus peptide of the cleaved subunit of calpain I. While basal levels of activated calpain I were stable over incubation times, 1 nM dopamine (DA) produced an initial 32% increase (5 min) in the 76 kDa protein followed by a 53% decrease in this band at 20 min of incubation. The DA-induced changes in activated calpain I immunoreactivity were blocked by the calpain inhibitor peptide, N-acetyl-Leu-Leu-norleucinal(100 microM) or by EGTA. Basal levels of the 76 kDa band were not affected by the calpain inhibitor. These changes in activated calpain I, elicited by DA, are in accord with the DA-induced decreases in the levels of the calpain substrate, gamma PKC (Yurko-Mauro and Friedman; J Cell Biochem [Abstr] 180:80, 1994; J Neurochem 65: 1622-1630, 1995) and suggest that DA activates this Ca(++)-dependent protease in its regulation of neuronal signal transduction.

Animals↗
PubMed1996

Summary of findings from the United States Collaborative Study of children treated for phenylketonuria.

The Collaborative Study of children treated for phenylketonuria (PKUCS) was conducted to investigate prospectively the effects of dietary restriction of phenylalanine on the growth and development of these children. Patients with classic phenylketonuria were identified by newborn screening and began treatment shortly thereafter. All were given the restricted diet until age 6 years, when half were randomly assigned to continue and half to discontinue dietary therapy. By age 10 years, 35% had deviated from randomization. The effects of diagnostic, treatment, and psychosocial factors on cognitive test scores were evaluated through 12 years of age. After controlling for parent IQ, significant correlations were noted between various measures of control of blood phenylalanine and their scores on intelligence, reading, spelling and behavior tests, but not for arithmetic or language scores. Bender Gestalt test scores were related to phenylalanine level at the time of testing, but not to early treatment history. These findings strongly support the importance of early initiation of dietary treatment and continuation of therapy throughout childhood.

Child↗
PubMed1996

Sporadic cardiac myxomas and tumors from patients with Carney complex are not associated with activating mutations of the Gs alpha gene.

Cardiac myxomas are rare tumors that may be encountered sporadically or in the context of the Carney complex. The molecular basis for the development of cardiac myxomas and Carney complex tumors is unclear. Pathological myocardial function and myocardial hypertrophy have been associated with alterations in the heterotrimeric GTP-binding proteins. The postulated proto-oncogenic character of the gene encoding the alpha sub-unit of the stimulatory GTP-binding protein Gs alpha (gsp) in pituitary and thyroid tumors, the finding of identical somatic gsp mutations in the myocardium of patients with McCune-Albright syndrome, and the associated endocrine anomalies of the Carney complex prompted us to investigate the occurrence of activating missense mutations in the Gs alpha gene in 10 sporadically occurring atrial myxomas and in 8 tumors from 7 patients with Carney complex. No gsp mutations could be demonstrated by using the polymerase chain reaction and denaturing gradient gel electrophoresis complemented by direct DNA sequencing. Thus, activating Gs alpha mutations neither are associated with the development of atrial myxomas, nor can be demonstrated in other tumors from patients with Carney complex. The significance of these mutations in the myocardium of asymptomatic patients with McCune-Albright syndrome remains to be determined.

Adult↗
PubMed1996

A novel mutation of presenilin 1 in familial Alzheimer's disease in Israel detected by denaturing gradient gel electrophoresis.

Germline mutations in the presenilin 1 (PS1) gene apparently account for the majority of early-onset, familial Alzheimer's disease (AD). Using a mutation-screening strategy (denaturing gradient gel electrophoresis; DGGE), we analyzed a large family with early onset AD and seizures. The patients in this family showed a novel missense mutation in exon 5 of the PS1 gene (A to T change in codon 120, altering glutamine to aspartic acid). This novel mutation is located within the second hydrophilic domain of the molecule, a region not particularly involved in previously described germline mutations, and is of unknown biological significance. These results also demonstrate that DGGE can be used effectively to screen for mutations within this gene.

Alzheimer Disease↗
PubMed1996

Effect of prenatal cocaine on dopamine receptor-G protein coupling in mesocortical regions of the rabbit brain.

The effects of in utero exposure to cocaine on dopamine receptors in the frontal and cingulate areas of the developing rabbit cortex were assessed by examining receptor-mediated stimulations in GTP binding to alpha-subunits of G proteins. Pregnant Dutch-belted rabbits received intravenous injections of 4 mg/kg of cocaine HCl twice a day on gestational days 8-29, cortical membranes were prepared from their progenies on postnatal days 10-100 and dopamine-stimulated [35S] guanosine-5'-[gamma-thio]triphosphate (GTP gamma S) binding to membrane G alpha proteins was measured. Dopamine increased [35S]GTP gamma S binding to G alpha s and G alpha i. These increases in [35S]GTP gamma S binding reflect the stimulation of D1- and D2-dopamine receptors, respectively. The ability of dopamine to stimulate the binding of [35S]GTP gamma S to G alpha s but not to G alpha i was reduced in both frontal and cingulate cortices obtained from cocaine-exposed animals when examined at 10, 50 or 100 days of age. Prenatal cocaine exposure was also shown to reduce dopamine-stimulated [alpha-32P]GTP binding to G alpha s without influencing binding to G alpha i. The muscarinic cholinergic receptor-evoked increases in [35S]GTP gamma S binding to G alpha i and G alpha o were not altered. Immunoblot analyses revealed no differences in the levels of these alpha subunits in membranes from cocaine-exposed animals vs controls. Furthermore, prenatal cocaine did not affect [3H]8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin-7- olhemimaleate binding to cortical D1 dopamine receptors. The results suggest that prenatal exposure of rabbits to cocaine selectively uncouples the D1 dopamine receptor from its G protein in mesocortical brain areas and that this change persists through postnatal day 100.

Animals↗
PubMed1996

Receptor-mediated activation of G proteins is increased in postmortem brains of bipolar affective disorder subjects.

Guanine nucleotide binding proteins (G proteins) have been implicated in the pathophysiology of bipolar affective disorder. In the present investigation receptor-mediated G protein activation and changes in G protein trimeric state were examined in frontal cortical membranes obtained from postmortem brains of bipolar affective disorder subjects and from age-, sex-, and postmortem interval-matched controls. Stimulation of cortical membranes with serotonin, isoproterenol, or carbachol increased guanosine 5'-O-(3-[35S]thiophosphate) ([35S]GTP gamma S) binding to specific G alpha proteins in a receptor-selective manner. The abilities of these receptor agonists to stimulate the binding of [35S]GTP gamma S to the G alpha proteins was enhanced in membranes from bipolar brains. Immunoblot analyses showed increases in the levels of membrane 45- and 52-kDa G alpha S proteins but no changes in the amounts of G alpha i, G alpha o, G alpha Z, G alpha q/11, or G beta proteins in membrane or cytosol fractions of bipolar brain homogenates. Pertussis toxin (PTX)-activated ADP-ribosylations of G alpha i and G alpha o were enhanced by approximately 80% in membranes from bipolar compared with control brains, suggesting an increase in the levels of the trimeric state of these G proteins in bipolar disorder. Serotonin-induced, magnesium-dependent reduction in PTX-mediated ADP-ribosylation of G alpha i/G alpha o in cortical membranes from bipolar brains was greater than that observed in controls, providing further evidence for enhanced receptor-G protein coupling in bipolar brain membranes. In addition, the amounts of G beta proteins that coimmunoprecipitated with the G alpha proteins were also elevated in bipolar brains. The data show that in bipolar brain membrane there is enhanced receptor-G protein coupling and an increase in the trimeric state of the G proteins. These changes may contribute to produce exaggerated transmembrane signaling and to the alterations in affect that characterize bipolar affective disorder.

Adenylyl Cyclases↗
PubMed1996

Guanine nucleotide regulatory proteins, Gq and Gi1/2, mediate platelet-activating factor-stimulated phosphoinositide metabolism in immortalized hippocampal cells.

Platelet-activating factor (PAF) may be a neuromodulator involved in neural cell differentiation, cerebral inflammation, and ischemia. The PAF receptor is a member of the G protein-coupled receptor superfamily. In the present study, we sought to define the specific G protein(s) that mediate PAF-stimulated phosphoinositide (PI) metabolism in an immortalized hippocampal cell line, HN33.11. PAF increased the production of 3H-labeled inositol phosphates (IPs) with EC50 values of 1.2-1.5 nM. The effect of PAF on 3H-IPs formation was completely blocked by the PAF antagonist BN 50739 at a concentration of 300 nM. Pertussis toxin pretreatment attenuated PAF-stimulated 3H-IPs production by 20-30% (p < 0.05). Consistent with a role for Gi1/2 in this response, antiserum against G alpha i1/2 blocked the response to a similar degree. Pretreatment of permeabilized cells with G alpha q/11 antiserum attenuated the response by 70% (p < 0.05), suggesting a role for Gq/11 in mediating the PAF response in this cell line. Stimulation with PAF increased [alpha-32P]-GTP binding to both G alpha q and G alpha i1/2 proteins. Moreover, specific [3H]PAF binding sites coprecipitated with G alpha q and G alpha i1/2 proteins. The results suggest that PAF-stimulated PI metabolism in HN33.11 cells is mediated by both Gq and Gi1/2 proteins.

Animals↗