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Biomedical subjects

A Reshef

Publications and source records attributed to A Reshef.

At least 37 records · Page 2Linked to original sources
PubMed1998

Role of gamma/delta T cells in a patient with CD4+CD3- lymphocytosis, hypereosinophilia, and high levels of IgE.

BACKGROUND: CD4+CD3- T cells have previously been shown to play a pathogenic role in the hypereosinophilic syndrome by secreting IL-5 and IL-4. OBJECTIVES: The goal of this study was to study the role of CD4+CD3- and other T-cell subsets in a patient with eosinophilia, dermatitis, and a high level of IgE (100,000 IU/mL) in the serum. METHODS: We isolated PBMCs and performed flow cytometry, cell cultures, and in vitro assays of Ig, lymphokine production, and cell-mediated cytotoxicity. RESULTS: Flow cytometric and immunohistochemical analysis of the PBMCs revealed a major population (consisting of approximately 85% of the CD4+ T cells) that lacked expression of CD3 and T-cell receptors on the cell surface (CD4+CD3- T cells), but did express CD3 peptides in the cytoplasm. Activation of the PBMCs in vitro resulted in a 100-fold greater than normal release of IL-4, whereas IFN-gamma production was less than normal, suggesting a predominantly type 2 helper functional phenotype of the CD4+CD3- T cells. Importantly, both CD4-CD8(low) Vdelta1+ T-cell receptor gammadelta+ and CD4+CD3- T cells were cultured from the PBMCs. The former secreted IFN-gamma exclusively, whereas the latter secreted both IL-4 and IFN-gamma. Furthermore, only the T-cell receptor gammadelta+ lymphocytes were cytotoxic to autologous B-lymphoblastoid cells and specifically inhibited IgE production in cultures of autologous polyclonally stimulated PBMCs. CONCLUSIONS: The results suggest that CD8(low) Vdelta1+ T-cell receptor gammadelta+ clones functionally counteract IgE-inducing effects of type 2 CD4+CD3- helper cells in this patient with hypereosinophilic syndrome.

Adult↗
PubMed1997

Activation and inhibition of protein kinase C protect rat neuronal cultures against ischemia-reperfusion insult.

The effect of activation and inhibition of protein kinase C (PKC) on the capacity of neurons to resist subsequent ischemic and ischemia-reperfusion-induced cell injury, was studied in a model of primary rat neuronal cultures, subjected to chemical ischemia. Activation of PKC by 1,2 dioctanoyl-rac-glycerol (DOG; 1 microM), or phorbol 12-myristate 13-acetate (PMA; 1 microM), as well as inhibition of the enzyme by chelerythrine (10 microM), or by calphostin C (0.2 microM), 10 min before the ischemic insult, resulted in acquisition of resistance against the two insults. The length of the 'time window of protection' induced by exposure to DOG and to chelerythrine was studied and found to last for several days. The results demonstrate an apparently 'paradoxical' phenomenon, in which both activation and inhibition of PKC in the same tissue induce protection. This may be explained by differential activation of various PKC isoforms.

Alkaloids↗
PubMed1997

Elimination of cholesterol in macrophages and endothelial cells by the sterol 27-hydroxylase mechanism. Comparison with high density lipoprotein-mediated reverse cholesterol transport.

Cultured macrophages and endothelial cells have been reported to secrete 27-oxygenated metabolites of cholesterol. This mechanism was compared with the classical high density lipoprotein (HDL)-dependent reverse cholesterol transport. Under standard conditions, macrophage preparations had considerably higher capacity to secrete 27-hydroxycholesterol and 3beta-hydroxy-5-cholestenoic acid than had endothelial cells and fibroblasts. Western blotting showed that lung macrophages contained the most sterol 27-hydroxylase protein of the cells tested. The relative amounts of 3beta-hydroxy-5-cholestenoic acid produced by the macrophages were also highest. Macrophages derived from monocytes of patients with sterol 27-hydroxylase deficiency did not secrete 27-oxygenated products, demonstrating that sterol 27-hydroxylase is the critical enzyme for the conversion of cholesterol into the 27-oxygenated steroids. That sterol 27-hydroxylase is responsible not only for 27-hydroxylation of cholesterol but also for the further oxidation of this steroid into 3beta-hydroxy-5-cholestenoic acid was shown with use of tritium-labeled 27-hydroxycholesterol and an inhibitor of sterol 27-hydroxylase. Secretion of 27-oxygenated products by the cultured macrophages as well as the ratio between the alcohol and the acid appeared to be dependent upon total 27-hydroxylase activity, the availability of substrate cholesterol, and the presence of an acceptor for 27-hydroxycholesterol in the medium. With albumin as extracellular acceptor, the major secreted product was 3beta-hydroxy-5-cholestenoic acid. Under such conditions, secretion of labeled 27-oxygenated products was higher than that of labeled cholesterol from lung alveolar macrophages preloaded with [4-14C]cholesterol. With HDL as acceptor, 27-hydroxycholesterol was the major secreted product, and the total secretion of labeled 27-oxygenated products was only about 10% of that of labeled cholesterol. Thus, 27-hydroxycholesterol and cholesterol may compete for HDL-mediated efflux from the cells. The results support the contention that the sterol 27-hydroxylase-mediated elimination of cholesterol is more important in macrophages than in endothelial cells. This mechanism may be an alternative and/or a complement to the classical HDL-mediated reverse cholesterol transport in macrophages, in particular when the concentration of HDL is low.

Albumins↗
PubMed1997

Identification of two novel LDL receptor gene defects in French-Canadian pediatric population: mutational analysis and biochemical studies.

Familial hypercholesterolemia (FH) is at least twofold more prevalent in French Canadians from Québec than in most Western populations. Although our recent data confirmed this high frequency of heterozygous FH in our pediatric population with hypercholesterolemia, none of the five established molecular defects for the French-Canadian population was detected in 29% of the unrelated French-Canadian children characterized by a persistent increase in LDL (low density lipoprotein receptor) cholesterol and a positive parental history of hyperlipidemia (Assouline et al., 1995). To probe for new mutations, six of these molecularly undiagnosed children were investigated as index patients. By using single-strand conformation polymorphism analysis and DNA sequencing, two novel mutations were identified in two of these subjects: (1) 7-base pair (bp) duplication following nucleotide 681 (according to the cDNA sequence) in exon 4 (681ins7), which causes a frameshift, the introduction of a stop at codon 208, and premature chain termination, and (2) A to G change in exon 8 substituting a tyrosine for a cysteine at amino acid 354 (Y354C). A third subject carried the recently reported exon 10 mutation (Y468X), whereas the remaining three patients demonstrated various known polymorphisms with no effect on gene product. Rapid molecular assays were developed to detect the two new mutations as well as the Y468X mutation. Screening of our cohort showed heterozygosity in 1/88, in 2/88, and in 2/88 of patients for the 681ins7, the Y354C, and the Y468X mutations, respectively.

Amino Acid Sequence↗
PubMed1997

Allergenicity of the pollen of Pistacia.

Differences in IgE binding and skin responses to pollen extracts of four species of Pistacia, and some immunochemical characteristics of this pollen were investigated. The incidence of positive SPT among atopic patients varied between 31.5% to the pollen extracts of P. vera and 24.6% to P. palaestina. The antigens are located on the exine of the grains as well as in their cytoplasm. Some of the antigens are common to all four species, whereas others seem to be specific. Cross-reactivity was found among the four species of Pistacia and between them and Schinus terebintifolious. Five conspicuous IgE-binding bands were observed in the immunoblots of the four examined species, the bands of 49, 57, 64, 68, and 79 kDa. The 36-37-kDa band of P. lentiscus and the 60- and 84-kDa bands of P. atlantica and P. vera were also noticeable. As the flowering seasons of Pistacia and Schinus do not overlap, the patients are exposed to such pollen for more than 4 months a year. Apparently, Pistacia pollen is a major source of allergy.

Binding Sites, Antibody↗
PubMed1996

Preconditioning of primary rat neuronal cultures against ischemic injury: characterization of the "time window of protection'.

Primary rat neuronal cultures can be preconditioned against ischemic damage by several mechanisms. In the present study we established a new model system in order to characterize the "time window of protection' obtained by preconditioning of neurons with adenosine. Ischemia was simulated by exposure of the cultures to iodoacetate (100 microM) for 150 min, with a post-ischemic reperfusion period of 60 min. Ischemic injury was assessed by the release of lactic dehydrogenase (LDH) to the medium during the ischemic period and ischemia-reperfusion damage by the Trypan blue exclusion test. Exposure of the neuronal cultures to the ischemic or ischemia-reperfusion insult resulted in severe damage to the neurons, manifested for the former insult in a 5.4-fold increase in the release of LDH and for the latter insult in an 8.5-fold increase in the proportion of stained cells by the Trypan blue exclusion test. Preconditioning by short exposure (5 min) of the cultures to iodoacetic acid (simulating sublethal ischemia), or to adenosine (1 mM) and the A1 adenosine receptor agonist N6-(R)-phenylisopropyladenosine (R-PIA; 1 and 100 microM), prior to the insult, partially protected the neurons against the damage. The time-course of the development and waning of the resistance against the two insults following preconditioning exhibited different patterns. The resistance obtained against the ischemic insult developed rapidly, being maximal for all substances at 10 min (the shortest time window studied), and lasted up to 1 h for iodoacetate, 3 h for R-PIA and 24 h for adenosine. In contrast, the protection induced by adenosine and R-PIA against ischemia-reperfusion injury developed relatively slowly, being maximal at 3 h, but lasted longer, up to 48 h. At this time the time-response curve exhibited a second peak of protection. The waning of protection against the two insults was found to continue into a period of increased sensitivity to the insults. This phenomenon was more intense for preconditioning with iodoacetate, and especially against the ischemic injury. The results suggest that in the neurons, different mechanisms may mediate the adenosine-induced preconditioning against the ischemic or ischemia-reperfusion injury. In addition, the results support the possibility that the relatively long "time window of protection', induced by adenosine and R-PIA against ischemia-reperfusion insult, reflects a combination of two different preconditioning mechanisms.

Animals↗
PubMed1996

Neuroprotective strategy for Alzheimer disease: intranasal administration of a fatty neuropeptide.

Neurodegenerative diseases, in which neuronal cell disintegrate, bring about deteriorations in cognitive functions as is evidenced in millions of Alzheimer patients. A major neuropeptide, vasoactive intestinal peptide (VIP), has been shown to be neuroprotective and to play an important role in the acquisition of learning and memory. A potent lipophilic analogue to VIP now has been synthesized, [stearyl-norleucine17]VIP ([St-Nle17]VIP), that exhibited neuroprotection in model systems related to Alzheimer disease. The beta-amyloid peptide is a major component of the cerebral amyloid plaque in Alzheimer disease and has been shown to be neurotoxic. We have found a 70% loss in the number of neurons in rat cerebral cortical cultures treated with the beta-amyloid peptide (amino acids 25-35) in comparison to controls. This cell death was completely prevented by cotreatment with 0.1 pM [St-Nle17]VIP. Furthermore, characteristic deficiencies in Alzheimer disease result from death of cholinergic neurons. Rats treated with a cholinergic blocker (ethylcholine aziridium) have been used as a model for cholinergic deficits. St-Nle-VIP injected intracerebroventricularly or delivered intranasally prevented impairments in spatial learning and memory associated with cholinergic blockade. These studies suggest both an unusual therapeutic strategy for treatment of Alzheimer deficiencies and a means for noninvasive peptide administration to the brain.

Administration, Intranasal↗
PubMed1996

Molecular genetics of familial hypercholesterolemia in Israel.

Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by a multitude of low density lipoprotein receptor (LDL-R) mutations. The purpose of the current investigation was to define the spectrum of mutations causing FH in Israel and determine their relative distribution among diverse origin groups. A total of 193 FH families were recruited in Israel, 54 of them through the MED PED (Make Early Diagnosis Prevent Early Death) FH program. Molecular analysis of the LDL-R using single-strand conformation polymorphism (SSCP) or denaturing gradient gel electrophoresis (DGGE) or both has been completed in 95 index cases. This analysis resulted in the identification of 15 LDL receptor mutations, including 7 novel mutations (del 197, C308G, R385W, splice junction mutation of intron 14, del 328, del 502-505, stop 10, del 165), that were present in 49 index cases (52%). The 15 mutations are mapped to three known functional domains of the receptor (7 in the LDL-binding region, 7 in the epidermal growth factor precursor homology region and 1 in the membrane-spanning region). Screening for the identified mutations in the remaining 98 index cases enabled the molecular diagnosis of 31 additional cases. It is therefore concluded that 80 out of 193 index cases (41%) harbor 1 of the 15 mutations described here. Three mutations-del197 (FH-Lithuania), D147H (FH-Sephardic), and stop660 (Lebanese allele)-were found in a total of 66 index cases (34%); these may be regarded as founder mutations in the three respective origin groups. In conclusion, in Israel molecular heterogeneity at the LDL receptor gene locus reflects the ethnic distribution of its origin groups. The results of the present investigation provide valuable diagnostic tools for a subset of the Israeli patients with FH who are at high risk for atherosclerosis and its complications.

Arabs↗
PubMed1996

Cerebrotendinous xanthomatosis: a family study of sterol 27-hydroxylase mutations and pharmacotherapy.

We examined the phenotypic characteristics, molecular genetics and optimal pharmacological treatment of cerebrotendinous xanthomatosis (CTX) in an English family with combined hyperlipidaemia. The proband presented in adulthood with classical clinical characteristics of CTX, a greater than tenfold elevation in plasma cholestanol and combined hyperlipidaemia. His brother also had typical features of CTX without the presence of dyslipidaemia. Genotyping revealed that the two brothers were compound heterozygotes for a novel missense mutation in exon 2 (R94Q) and for a recently described nonsense mutation in exon 5, of the sterol 27-hydroxylase gene (CYP27). Analysis of all available family members revealed that hyperlipidaemia did not co-segregate with the presence of a CYP27 mutant allele. Trial of therapy showed that the lowest plasma sterol and triglyceride concentrations and cholestanol:cholesterol ratio were achieved with the combination of chenodeoxycholic acid (CDCA) 750 mg/day, a primary bile acid, and simvastatin 40 mg/day, an inhibitor of 3-hydroxy-3-methyl-glutaryl coenzyme A reductase. CDCA alone and simvastatin alone significantly lowered plasma cholestanol concentration, but the decrease was greater with the former. After 1 year there was significant improvement in both cognitive and motor function with regression of tendon xanthomata on computerized tomography. We conclude that CTX in this English pedigree is probably due to compound mutant alleles in CYP27, that combined hyperlipidaemia in this family is unrelated to CTX, and that this complicated condition responds optimally to the combination of CDCA and simvastatin.

Adolescent↗
PubMed1996

Atopy, bronchial hyperresponsiveness, and peak flow variability in children with mild occasional wheezing.

BACKGROUND: Children who suffer from recurrent wheezy episodes are often promptly classified as asthmatic. The aim of this study was to evaluate a population of mild wheezy children with repeatedly normal spirometric tests at rest for atopy, bronchial hyperresponsiveness, and peak expiratory flow variability. METHODS: Thirty nine children aged 6-16 years with 1-12 wheezy attacks during the previous year were recruited from a community paediatric primary health care clinic serving an urban Israeli population. The conditions for inclusion were a physician-diagnosed wheeze on auscultation and normal spirometric tests at rest on at least three occasions. Evaluation included skin prick tests for atopy and a physician-completed questionnaire. In addition, two tests of bronchial hyperresponsiveness (BHR) were performed--namely, exercise-induced bronchospasm and inhaled methacholine hyperresponsiveness--as well as diurnal variability of peak expiratory flow (PV). RESULTS: One or more tests of BHR/PV were positive in 27 (69%) but repeatedly negative in 12 (31%). In terms of frequency of wheezing attacks, atopy, and questionnaire responses, there were no differences between BHR/PV and non-BHR/PV children, with the exception of a history of chest radiography proven pneumonia (only noted in the BHR/PV group). Overall, evidence of atopy (mainly indoor allergens) was noted in 21 (56%) of those tested and parental smoking in 29 (74%) of households. Thirty-two (82%) of the children complained of an exercise-related wheeze, yet exercise-induced bronchospasm was only demonstrated in nine (23%). CONCLUSIONS: This selected group of wheezy children appears to be intermediate between a normal and clearly asthmatic population and, despite the recurrent wheezy attacks, some should probably not be classified as asthmatic by conventional criteria. Important aetiological factors in the symptomatology of these children may include parental smoking and atopy as well as other elements such as viral infections.

Adolescent↗
PubMed1995

Premature termination codon at the sterol 27-hydroxylase gene causes cerebrotendinous xanthomatosis in a French family.

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid-storage disease caused by mutations in the sterol 27-hydroxylase gene (CYP27). So far several mutations causing CTX have been identified and characterized. A new mutation creating an insertion of cytosine at position 6 in the cDNA, which is expected to result in a frameshift and a premature termination codon at codon 179, has been identified in a French family. The mutation creates a new site for the restriction endonuclease HaeIII.

Adult↗
PubMed1994

Stearyl-norleucine-vasoactive intestinal peptide (VIP): a novel VIP analog for noninvasive impotence treatment.

The present report relates to pharmaceutical composition for the treatment of male impotence. The transdermal application of a potent derivative of vasoactive intestinal peptide (VIP) coupled to a suitable hydrophobic moiety (e.g. stearyl-VIP) in a suitable ointment composition (e.g. Sefsol) enhances sexual activity and erection formation in a variety of impotence models in rats (sterile rats, diabetic rats, and animals with high blood pressure). Furthermore, exchange of the methionine in position 17 with norleucine enhances biological activity. Thus, stearyl-Nle17-VIP may be considered useful for the treatment of impotence.

Administration, Cutaneous↗
PubMed1994

Cerebrotendinous xanthomatosis: molecular diagnosis enables presymptomatic detection of a treatable disease.

We report an early molecular diagnosis of cerebrotendinous xanthomatosis (CTX) in a Jewish Moroccan family with two affected siblings. The proband displayed characteristic manifestations of the disease, whereas a younger brother, homozygous for the mutant allele, was asymptomatic. Clinical studies in the younger patient disclosed mild cognitive impairment, peripheral neuropathy, and abnormal EEG. Elevated plasma cholestanol levels were evident in both affected patients, with documented normal levels in the molecularly diagnosed heterozygous family members. Molecular characterization of affected CTX families provides early diagnosis and treatment of homozygotes in the presymptomatic state as well as identification of heterozygotes, which is crucial for genetic counseling and for prenatal diagnosis.

Action Potentials↗
PubMed1994

Cerebrotendinous xanthomatosis in the Israeli Druze: molecular genetics and phenotypic characteristics.

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid-storage disease caused by mutations in the sterol 27 hydroxylase gene (CYP27). Clinically, a multitude of neurological, skeletal, and vascular manifestations are usually present. Premature atherosclerosis has been reported in CTX and may be related to the metabolic derangement caused by the deficiency of the enzyme. A CYP27 nonsense mutation created by the deletion of cytosine376 has been identified in four Israeli Druze CTX patients residing in the same village. Molecular screening for this mutation in families of two probands revealed a total of 10 homozygotes and 28 heterozygotes whose clinical and biochemical characteristics are described. Overall, except for tendon xanthomas, most of the clinical manifestations progress with age. The CYP27 mutation was associated with modest differences in the levels of plasma total cholesterol (TC) and LDL cholesterol (LDL-C). The distribution of plasma concentrations of TC and LDL-C in the CTX families was consistent with a polygenic model. A similar model that includes also the effects of the CYP27 genotypes was not better supported by the data. It may be concluded that, in CTX, the presence of a CYP27 mutation does not significantly affect the plasma concentrations of lipids and lipoproteins. Therefore, the reported increased prevalence of atherosclerosis in this disease must be related to other factors.

Adolescent↗