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H Cohen

Publications and source records attributed to H Cohen.

At least 37 records · Page 2Linked to original sources
PubMed2004

Electrically conductive 2D-PAN-containing surfaces as a culturing substrate for neurons.

In the present contribution we report on a novel route to synthesize 2D-polyaniline (2D-PAN) on sulfonated-poly(styrene) (SPS) templates by allowing first monomer assembly followed by chemical oxidation to achieve polymerization. We show that Aplysia neurons grown on 2D-PAN exhibit an unusual growth pattern and adhesion to this conducting substrate that is manifested by the formation of giant lamellipodia. The lamellipodial domains are characterized by small gap between the plasma membrane and the 2D-PAN substrate (ca. 30 nm) and actin rich skeleton resembling the skeleton of growth cones. This behavior is characteristic to uniform substrates containing only 2D-PAN. However, in patterned substrates containing additionally poly(L-lysine) Aplysia neurons prefer to extend new neurites on the poly(L-lysine) domains.

Actins↗
PubMed2004

The presence of erythropoietin receptors in the human peripheral nervous system.

Erythropoietin (EPO) is a well-known hematopoietic factor and a major determinant of tissue oxygenation. EPO receptors have been identified on a wide variety of non-erythroid cell types including human central nervous system and peripheral nervous system of animal models. The presence or function of EPO receptors in human peripheral nervous system is unknown. By examining nerve segments from radicular and autonomic nerves using immunohistochemical methods, we demonstrated the presence of EPO receptors on myelin sheath of radicular nerves in the human peripheral nervous system.

Humans↗
PubMed2003

Perception and production of facial and prosodic emotions by chronic CVA patients.

Variable etiology, limited testing of emotions and inclusion of patients in acute and chronic phases have made it difficult to specify the extent of right hemisphere involvement in the processing of emotional material. In addition, there is an absence of data concerning CVA patients' long-term abilities to process emotional information. Two groups of subjects with unilateral brain damage (15 RBD, 17 LBD), matched for chronicity (minimum 12 months post-CVA), etiology (ischemic CVA), duration of hospitalization and other variables, and an appropriate control group participated in two experiments to address these concerns. In the first experiment, subjects were given a series of tasks (discrimination, identification, imitation, production on request) to assess their processing of facial expressions of the six universal emotions [P. Ekman, W. Friesen, Unmasking the face, Prentice-Hall, Englewood Cliffs, 1975]. The results showed that three emotions (surprise, happiness, fear) discriminate between RBD and LBD patients and controls, with RBD subjects performing worse than the other groups on the identification task only. Using tasks of the same nature, the second experiment investigated the processing of emotional prosody. The results showed that three emotions (fear, sadness, anger) discriminate between RBD and LBD patients and controls, with RBD subjects again performing worse than the others on the discrimination, imitation and production on request tasks. LBD subjects performed as well as normal controls on almost all tasks. The RBD subjects were the only ones who showed relatively consistent impairment in the processing of both facial and prosodic emotional information. Taken together, these data strongly suggest that the right hemisphere is preferentially involved in processing emotional information in the chronic phase of brain damage.

Acoustic Stimulation↗
PubMed2003

Productivity of lexical categories in French-speaking children with cochlear implants.

The productivity of lexical categories was studied longitudinally in a sample of 17 young hearing-impaired French-speaking children with cochlear implants. Age of implantation ranged from 22 months to 76 months. Spontaneous speech samples were collected at six-month intervals over a period of 36 months, starting at the one-word stage. Four general measures of their linguistic production (number of utterances, verbal fluency, vocabulary, and grammatical production) as well as 36 specific lexical categories, according to the CHILDES codes, were computed in terms of tokens, i.e., total number of words. Cochlear-implanted children (CI) were compared to a French database of normally hearing children aged 2-4 compiled by the first author. Follow-up results indicate that, at the two-year post-implantation follow-up, noun, and verb morphology was significantly impaired. At the three-year follow-up, the cochlear-implanted group had recovered on adjectives, determiners and nouns, main verbs, and auxiliaries. The two groups differed significantly in processing locative adverbs, prepositions, pronouns, and verbs (infinitive verb, modal, and modal lexical), but individual variability within the cochlear-implanted group was substantial. Results are discussed in terms of recovery and developmental trends and variability in the acquisition of lexical categories by French children two years and three years post-implantation.

Child↗
PubMed2003

Effect of the antioxidant Mesna (2-mercaptoethane sulfonate) on experimental colitis.

Reactive oxygen species play a key role in intestinal inflammation, although interventional studies using antioxidants have shown only weak beneficial effects both in humans and animals. Hence, our aim was to examine the possible beneficial effect of the antioxidant 2-mercaptoethane sulfonate (Mesna) on experimental colitis. Colitis was induced in rats by intrarectal instillation of trinitrobenzene sulfonic acid (TNB) followed immediately by intrarectal Mesna or saline, administered for 14 days, twice daily. A beneficial effect of Mesna was observed, resulting in a significant reduction in inflammation followed by almost full recovery. iNOS mRNA expression and myeloperoxidase (MPO) activity were significantly increased in the TNB-Mesna group. These results suggest that the induction of iNOS in the presence of Mesna reduced intestinal inflammation. Mesna probably resolved this inflammation by scavenging reactive oxygen species generated by the augmented infiltration of polymorphonuclear leukocytes.

Animals↗
PubMed2003

Rosiglitazone (PPARgamma-agonist) attenuates atherogenesis with no effect on hyperglycaemia in a combined diabetes-atherosclerosis mouse model.

BACKGROUND: The administration of peroxisome proliferator-activated receptor gamma (PPARgamma) agonists to low-density lipoprotein (LDL)-receptor-deficient mice resulted in a reduction in the atherosclerotic lesion area in male mice, but not in female mice. The male mice also exhibited reduction in insulin resistance while the female mice did not. To further examine the relationship between PPARgamma agonists, insulin resistance and atherosclerosis, we used the model of accelerated atherosclerosis in male apolipoprotein E (apoE)-deficient mice rendered diabetic by low-dose streptozotocin (STZ). METHODS: Male, apoE-deficient mice (n = 48) were randomly divided into four groups. To induce diabetes, two groups received low-dose STZ and two groups served as controls. After diabetes induction, rosiglitazone (a PPARgamma agonist) was administered by oral gavage to one of the diabetic and one of the non-diabetic groups. RESULTS: Rosiglitazone reduced significantly the atherosclerotic aortic plaque area in both diabetic and non-diabetic apoE-deficient mice: 340 +/- 54 vs. 201 +/- 27 micromol2 (p = 0.001) in diabetic mice; 243 +/- 22 vs. 158 +/- 27 micromol2 (p = 0.001) in non-diabetic mice. Also, rosiglitazone reduced the correlation coefficient between plasma glucose and the degree of atherosclerosis (p < 0.0025) without affecting plasma glucose levels. The rosiglitazone-treated mice, both diabetic and non-diabetic, had higher lipid levels. CONCLUSIONS: Rosiglitazone-treated animals showed less atherosclerosis despite higher lipid levels and similar glucose levels. These data suggest a direct anti-atherogenic effect of rosiglitazone on the arterial wall.

Animals↗
PubMed2002

Diuretic induced hyponatraemia in elderly hypertensive women.

Diuretics are recommended as first-line antihypertensive treatment in elderly patients. Although attention is usually paid to prevent hypokalaemia with diuretic therapy, risk of hyponatraemia is often ignored. We performed this study to characterise hypertensive patients at increased risk to develop hyponatraemia. We reviewed charts of hypertensive patients hospitalised in Chaim Sheba Medical Center for hyponatraemia from 1990 to 1997. Patients with other causes of hyponatraemia were excluded. The General Practice Maccabi database was used to estimate age and sex distribution of patients prescribed diuretics for hypertension. We identified 180 hypertensive patients (149 F, 31 M; mean age 76.4 +/- 9.2 years) hospitalised because of hyponatraemia. Across all age groups, odds ratio (OR) to develop hyponatraemia was three times higher for women vs men (OR 3.10, 95% confidence interval (CI): 2.07-4.67). One hundred and sixty-two patients (90%) were older than 65 years. Patients of both sexes older than 65 years were 10 times (and if they were older than 75 years 16 times) more likely to develop hyponatraemia than those younger than 65 years (OR 9.87, 95%, CI: 5.93-16.64). Most patients (74.5%) used a thiazide-based diuretic; only 10% used a low dose (<25 mg/day). In 37% of patients diuretics were used for more than 1 year before hyponatraemia developed. Diuretic-induced hyponatraemia may be insidious and appear even after prolonged diuretics use. Elderly women seem to be at particularly high risk. In this population diuretic use should be associated with close monitoring of sodium and potassium levels.

Aged↗
PubMed2002

The PFA-100: a potential rapid screening tool for the assessment of platelet dysfunction.

The PFA-100 is a device that simulates high shear dependent platelet function in vitro and thus is particularly useful for screening for von Willebrand's disease (VWD). The aim of this study was to assess the overall potential of the PFA-100 as a primary clinical screening tool using the wide spectrum of clinical samples assessed for platelet function within our institution. The PFA-100 test was performed using both collagen/ADP (CADP) and collagen/epinephrine (CEPI) cartridges on samples from 337 patients with a wide variety of haemostatic defects. One hundred and eighty-two patients were defined as having normal platelet function based on classical laboratory tests and von Willebrand factor levels. The overall clinical sensitivity of the PFA-100 for platelet abnormalities (including VWD) was 81% for CADP and 86% for CEPI. The overall specificity was found to be 82% for CADP and 80% for CEPI. When utilizing both cartridges in combination (with both results either higher or lower than the upper cutoff of the normal ranges), the overall false positive and false negative rates were 12% and 6%, respectively. The PFA-100 proved to be sensitive in detecting classical defects by giving prolonged closure times in samples from patients with major platelet function defects (e.g. von Willebrand's disease, Glanzmann's thrombasthenia and Bernard Soulier syndrome). However, there were a small number of false negative results (6%) obtained with various milder platelet defects (e.g. Hermansky Pudlak syndrome, storage pool and release defects, type I VWD and macrothrombocytopenia). The PFA-100 test provides a useful rapid screening tool and should increase the efficiency and reduce the cost of the routine diagnosis of platelet dysfunction.

Adenosine Diphosphate↗
PubMed2002

Ki67 antigen and PCNA proliferation markers predict survival in anorectal malignant melanoma.

AIMS: To find a possible correlation of Ki67 antigen and proliferating cell nuclear antigen (PCNA) with prognosis in anorectal malignant melanoma. METHODS AND RESULTS: Thirty patients with anorectal malignant melanoma were studied. The percentage of tumour cells stained for Ki67 and PCNA in paraffin sections was assessed. Mode of treatment (local excision or abdominoperineal resection), depth of tumour invasion, attempt at cure as defined by complete tumour excision and absence of distant metastases at presentation, tumour blood vessel invasion, and tumour necrosis, as well as Ki67 and PCNA, were all correlated with survival. By univariate analysis, PCNA, Ki67, attempt at cure, local excision (and not abdominoperineal resection), and depth of invasion were all significantly associated with longer survival. By multivariate analysis, only PCNA was significantly associated with survival, while Ki67 showed a significant positive correlation with PCNA. With a cut-off point of 40%, patients with lower Ki67 scores showed survival advantage over those with higher Ki67 scores (P=0.0004). With a cut-off point of 80%, patients with lower PCNA scores showed survival advantage over those with higher PCNA scores (P=0.0001). The staining for proliferation markers was also associated with depth of tumour invasion. CONCLUSIONS: Ki67 and PCNA immunostaining in paraffin sections may be useful for the prediction of survival in patients with anorectal malignant melanoma. Larger studies are needed to confirm our results.

Aged↗
PubMed2001

High-pressure pulse-radiolysis study of the formation and decomposition of complexes with iron-carbon sigma bonds: mechanistic comparison for different metal centers.

Volumes of activation for the formation and homolysis of the transient complexes (hedta)Fe(III)-CO(2)(2-) and (hedta)Fe(III)-CH(3)(-) (HOCH(2)CH(2)N(CH(2)CO(2-))CH(2)CH(2)N(CH(2)CO(2-))(2) = hedta) were determined using high-pressure pulse-radiolysis techniques. A comparison of the results with those for analogous complexes with other central transition-metal cations (M(n+)) and ligands (L) points out that (i) the reaction of M(n)L(m) with aliphatic radicals (R(*)) proceeds via an interchange ligand substitution mechanism, i.e. M(n)L(m) + R(*) --> L(m-1)M(n+1)-R + L, (ii) the homolysis of the metal-carbon bonds naturally follows the same mechanism, and (iii) the volume of activation for the homolysis reaction depends strongly on the nature of the central cation, i.e. larger for M(n+1) = Cr(III), Co(III), Ni(III) and smaller for Fe(III). The volume of activation for the reaction (hedta)Fe(III)-CO(2)(2-) + CO(2)(*-) + 2H(+) --> Fe(II)(hedta)(H(2)O)(-) + CO + CO(2) was measured, and the results enable a tentative proposal for the nature of the transition state of this interesting reaction.

Carbon↗
PubMed2001

Changes in the practice of percutaneous coronary intervention: a comparison of enrollment waves in the National Heart, Lung, and Blood Institute (NHLBI) Dynamic Registry.

The National Heart, Lung, and Blood Institute Dynamic Registry includes 15 clinical sites in wave 1, and 16 sites in wave 2 as well as a data-coordinating center. The first wave of enrollment began in July 1997 and was completed in February 1998. The second wave began in February 1999 and ended in June 1999. There were a total of 2,526 patients in wave 1 and 2,109 patients in wave 2. Comprehensive pre-, intra-, and postprocedure (in-hospital) data were analyzed for changes between recruitment waves. Patients in wave 2 were more frequently nonwhite (p < or = 0.001), hypertensive by history (p < or = 0.001), had more significant noncardiac comorbidity (p < or = 0.01), and had more frequently undergone prior percutaneous coronary intervention (p < 0.05). Patients in wave 2 underwent percutaneous coronary intervention in a setting of acute coronary syndromes more frequently than wave 1 patients (p < or = 0.001). However, most interventions in both waves were performed on 1 vessel, irrespective of the extent of disease. Attempted lesions in wave 2 were longer (p < or = 0.001), less frequently totally occluded (p < or = 0.001), and more frequently in vessels with a prior stent (p < or = 0.01). Using the American Heart Association/American College of Cardiology lesion classification scheme, attempted lesions in wave 2 were less complex than those in wave 1 (p < or = 0.001). Stent use increased significantly from wave 1 (67%) to wave 2 (79%, p < or = 0.001) as did the use of platelet glycoprotein IIb/IIIa antagonists (wave 1, 24%; wave 2, 32%: p < 0.001). Procedural outcomes (angiographic success without major in-hospital adverse events) were excellent in both waves 1 (94.6%) and 2 (95.6%) and were not significantly different. However, the frequency of significant procedural coronary dissection and in- and out-of-laboratory abrupt closure were significantly less in wave 2 (p < or = 0.001) Discharge medications were more likely to include angiotensin-converting enzyme inhibitors, beta-adrenergic blocking agents, and hypolipidemic treatment in wave 2 than in wave 1 (p < or = 0.001). These data indicate a continuing aggressive approach to patient care over the time interval analyzed. Although overall procedural outcomes are excellent, procedural safety has been further enhanced. There is also a growing awareness of the importance of secondary prevention among interventional cardiologists.

Aged↗
PubMed2001

Recombination-mediated lengthening of terminal telomeric repeats requires the Sgs1 DNA helicase.

The Saccharomyces cerevisiae SGS1 gene encodes a RecQ-like DNA helicase, human homologues of which are implicated in the genetic instability disorders, Bloom syndrome (BS), Rothmund-Thomson syndrome (RTS), and Werner syndrome (WS). Telomerase-negative yeast cells can recover from senescence via two recombinational telomere elongation pathways. The "type I" pathway generates telomeres with large blocks of telomeric and subtelomeric sequences and short terminal repeat tracts. The "type II" pathway generates telomeres with extremely long heterogeneous terminal repeat tracts, reminiscent of the long telomeres observed in telomerase-deficient human tumors and tumor-derived cell lines. Here, we report that telomerase-negative (est2) yeast cells lacking SGS1 senesced more rapidly, experienced a higher rate of telomere erosion, and were delayed in the generation of survivors. The est2 sgs1 survivors that were generated grew poorly, arrested in G(2)/M and possessed exclusively type I telomeres, implying that SGS1 is critical for the type II pathway. The mouse WS gene suppressed the slow growth and G(2)/M arrest phenotype of est2 sgs1 survivors, arguing that the telomeric function of SGS1 is conserved. Reintroduction of SGS1 into est2 sgs1 survivors restored growth rate and extended terminal tracts by approximately 300 bp. Both phenotypes were absolutely dependent on Sgs1 helicase activity. Introduction of an sgs1 carboxyl-terminal truncation allele with helicase activity restored growth rate without extending telomeres in most cases, demonstrating that type II telomeres are not necessary for normal growth in the absence of telomerase.

Animals↗
PubMed2001

Systematic review of long term anticoagulation or antiplatelet treatment in patients with non-rheumatic atrial fibrillation.

OBJECTIVE: To examine the benefits and risks of long term anticoagulation (warfarin) compared with antiplatelet treatment (aspirin/indobufen) [corrected] in patients with non-rheumatic atrial fibrillation. METHODS: Meta-analysis of randomised controlled trials from Cochrane library, Medline, Embase, Cinhal, and Sigle from 1966 to December 1999. Odds ratios (95% confidence intervals) calculated to estimate treatment effects. OUTCOME MEASURES: Fatal and non-fatal cardiovascular events, reductions of which were classified as benefits. Fatal and major non-fatal bleeding events classified as risks. RESULTS: No trials were found from before 1989. There were five randomised controlled trials published between 1989-99. There were no significant differences in mortality between the two treatment options (fixed effects model: odd ratio 0.74 (95% confidence interval 0.39 to 1.40) for stroke deaths; 0.86 (0.63 to 1.17) for vascular deaths). There was a borderline significant difference in non-fatal stroke in favour of anticoagulation (0.68 (0.46 to 0.99)); and 0.75 (0.50 to 1.13) after exclusion of one trial with weak methodological design. A random effects model showed no significant difference in combined fatal and non-fatal events (odds ratio 0.79 (0.61 to 1.02)). There were more major bleeding events among patients on anticoagulation than on antiplatelet treatment (odds ratio 1.45 (0.93 to 2.27)). One trial was stopped prematurely after a significant difference in favour of anticoagulation was observed. The only trial to show a significant difference in effect (favouring anticoagulation) was methodologically weaker in design than the others. CONCLUSIONS: The heterogeneity between the trials and the limited data result in considerable uncertainty about the value of long term anticoagulation compared with antiplatelet treatment. The risks of bleeding and the higher cost of anticoagulation make it an even less convincing treatment option.

Anticoagulants↗
PubMed2001

Family-based association study of the serotonin transporter promoter region polymorphism (5-HTTLPR) in attention deficit hyperactivity disorder.

Low serotonin activity has been associated in both animal and human studies with measures of impulsivity, aggression, and disinhibited behaviors. Recently, a common 44-bp deletion in the promoter region of the serotonin transporter (5-HTTLPR) that results in reduced transcription and lower transporter protein levels was described. Toward unraveling a possible role of the 5-HTTLPR polymorphism in childhood disruptive behaviors, we examined this gene in attention deficit hyperactivity disorder (ADHD), a heterogeneous childhood disorder in which three phenotypes are recognized by DSM IV criteria: inattentive (type I), hyperactive-impulsive (type II), and combined type (type III). By using the haplotype relative risk design, a group of 98 triads (both parents and proband child) were tested for a possible association between 5-HTTLPR and ADHD. A significant decrease in the short/short 5-HTTLPR genotype was observed in the ADHD type III combined group (10.29% vs. 30.88%) compared with the HRR-derived control group (likelihood ratio = 9.62, P = 0.008, n = 68 triads). Similar results were observed when allele frequencies were compared (likelihood ratio = 3.81, P = 0.05, n = 136 alleles). These first findings should be interpreted cautiously until replicated in independently recruited clinical samples.

Adolescent↗
PubMed2001

Acquisition of lexical morphology in simple partial epilepsy.

In the study of language acquisition following early brain damage, results have been divergent. On one hand, some studies claim that language eventually resumes to normal, whereas, on the other hand, studies show lasting deficits throughout development. Discrepancies in the results could arise from different etiologies and tests used. This study attempts to determine the extent to which the development of verb production is affected in later development in children who had simple partial epilepsy (SPE). Measures of diversity and fluency of three verb types, namely main verbs, auxiliary and copula verbs, and nonfinite verbs were used on three children diagnosed as SPE and compared to control groups. Our main results show a limited production of auxiliary verbs. Further analysis of their productions suggest a telegraphic style of speech, as reflected by a superior production of nonfinite verb type compared with normal children. These findings are interpreted as reflecting long-lasting consequences of early brain damage with respect to language development.

Brain↗