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Biomedical subjects

M Kushnir

Publications and source records attributed to M Kushnir.

At least 19 recordsLinked to original sources
PubMed2006

Diagnostic value of vestibular evoked myogenic potentials in cerebellar and lower-brainstem strokes.

BACKGROUND: Vestibular evoked myogenic potentials (VEMPs) provide assessment of vestibular function. They consist in picking up compound muscle action potentials in the sternocleidomastoid (SCM) muscles in response to auditory stimulation of the vestibulum. VEMP testing has found application mainly in peripheral vestibular disorders, whereas reports about VEMPs in central vestibular lesions are rather scarce. AIMS OF THE STUDY: Based on the physiological connections between the cerebellum and the vestibular nuclei, we investigated the influence on VEMPs of cerebellar and lower-brainstem strokes. We examined whether or not this method may be suitable as a clinical tool for the evaluation of the extent of cerebellar strokes. PATIENTS AND METHODS: Nineteen patients with cerebellar ischemic stroke and 15 patients with lower-brainstem ischemic stroke (11 in the pons, four in the medulla) were included. The latencies and amplitudes of P13 and N23 in both groups of patients were compared with those obtained in a control group of 53 normal individuals. RESULTS: VEMP responses were obtained in all patients and controls. At the group level, mean peak latencies and amplitudes, and the number of subjects with significantly deviant values did not differ between patients and controls. There were no latency or amplitude differences ipsilaterally or contralaterally to the lesion. At the individual level, there was no correlation between laterality of lesion and that of P13 or N23 abnormalities in patients with cerebellar strokes; however, there were two patients (one pontine, one medullar stroke) who presented P13 and N23 latency abnormalities ipsilaterally to the lesion. CONCLUSION: Cerebellar strokes do not influence VEMPs. Moreover, despite previous reports, we were unable to find at a group level any statistically significant VEMP changes in patients with lower-brainstem strokes as compared with controls. Therefore, VEMPs do not appear a suitable tool for assessment of brainstem integrity in patients with posterior fossa strokes. However, they could constitute a sensitive method for documentation of involvement of the central vestibular pathways in patients with brainstem stroke.

Acoustic Stimulation↗
PubMed2005

[Opsoclonus myoclonus with ataxia].

Opsoclonus myoclonus with ataxia (OMA) is a rare neurological disorder. The syndrome is characterized by involuntary, conjugate, multidirectional eye movements accompanied by involuntary movements of limb or face, and sometimes ataxia, dysarthria, irritability, dementia, altered level of consciousness and even death. OMA is associated with various etiologies including infectious, toxic, drug-related, vascular and paraneoplastic conditions. Paraneoplastic opsoclonus myoclonus with ataxia (POMA) is more common in patients over 40 years of age and is usually associated with lung (especially small cell), breast and ovarian cancer but has also been reported with many other cancers. The syndrome is thought to be mediated by autoantibodies directed against onconeural antigens that are expressed by the tumor as well as by neurons. Studies from several laboratories were able to demonstrate a role for the cellular response in the pathogenesis of POMA. The results for treatment of this syndrome have been disappointing, although aggressive multimodality immunosuppressive treatments have been used. This is a case study of a patient with POMA who clearly demonstrates the difficulties in the diagnosis and treatment of this syndrome.

Aged↗
PubMed2001

H reflex behavior in Parkinson's disease patients and patients with extrapyramidal and pyramidal signs combined.

The H reflex was elicited in 21 normal subjects, 48 patients with Parkinson's disease (PD) and 22 patients with pyramidal and extrapyramidal signs combined (PESC). In most normal subjects (90.5%), in 29.2% of PD patients and 54.5% of patient with PESC the threshold for sensory fibers was lower than for motor fibers, and the H reflex was obtained before the M response for all duration stimuli in both legs. In 9.5% of normal subjects, 39.6% of PD patients with mild and moderate rigidity (according to the motor part of UPDRS) and 31.8% of patients with PESC, the threshold for the H reflex and M response was the same or the M response threshold was lower in at least one of the legs for short stimulus duration (0.1-0.2 ms). In 31.2% of PD patients (most of them with severe rigidity) and 13.7% of patients with PESC, the threshold for M response was lower for all stimulus duration in at least one of the legs, and it was obtained before H reflex. These very significant differences in behavior of the H reflex in PD patients (Fisher exact test, p<0.0001) that almost disappear in patients with PESC, could be possibly explained by changes in agonist-antagonist inhibition.

Adult↗
PubMed2000

H reflex behavior in Parkinson's disease patients. Effect of stimulus duration.

Electrical stimulus, with duration starting at 0.1ms and gradually increasing to 1.0ms, was used for eliciting the H reflex in 21 normal subjects and 48 patients with Parkinson's disease (PD). In 19 normal subjects (90.5%), the threshold for sensory fibers was lower than for motor fibers, and the H reflex was obtained before the M response for all duration stimuli. In 19 PD patients (39.6%), with mild or moderate rigidity (according to the motor part of UPDRS), the threshold for the H reflex and M response was the same or the M response threshold was lower in at least one of the legs for short stimulus duration (0.1-0.2ms). In 15 PD (31.2%) patients (most of them with severe rigidity), the threshold for M response was lower for all stimulus duration, and it was obtained before the H reflex. In 14 PD (29.2%) patients, the H reflex behavior was the same as in most normal subjects in one or both legs.These very significant differences in the behavior of the H reflex in PD patients (Fisher exact test, P<0.0001) could possibly be explained by changes in agonist-antagonist inhibition, and could be used as another parameter in the clinical assessment of extrapyramidal rigidity in PD patients.

Journal Article↗
PubMed2000

The role of gap junctions in seizures.

Electrotonic synaptic communication between neurons via gap junctions (gjs) is increasingly recognized as an important synchronizing mechanism in the brain. At the same time, the biology of central nervous system (CNS) gjs is being unravelled. The pathogenesis of the abnormal neuronal synchrony underlying seizures, formerly thought to be based mainly on chemical synaptic transmission, now includes a role for gap junctional communication. This concept has been strengthened by evidence from several in vitro seizure models, in which pharmacological manipulations of gap junctional communication predictably affect the generation of seizures: blockers diminishing seizures and enhancers increasing the seizures. Evidence for interneurons, coupled in part by gjs, generating synchronous neural network activity including seizures, is presented. Also neuromodelling studies, which have enhanced our ability to understand the functional role that gap junctional communication plays in the generation and maintenance of neural synchrony and seizures, are presented. Gap junctional communication appears to be a promising target for the development of future anticonvulsant therapy.

Animals↗
PubMed1998

Antineurofilament antibodies in postpolio syndrome.

We determined the levels of antineurofilament antibodies in 29 patients with postpolio syndrome (PPS), 26 stable postpolio (PP) patients, 22 patients with ALS, and 20 normal controls (NCs). Patients with PPS had higher antibody levels to cholinergic neurofilaments than did all other groups. PP patients and those with ALS had antibody levels similar to those of NCs. The antibody binding level showed no relation to the age of the patients, duration of disease, or motor score.

Adult↗
PubMed1998

Markedly elevated gamma-glutamyltransferase.

Gamma-glutamyltransferase (GGT) is a highly sensitive but poorly specific liver enzyme commonly used to detect hepatobiliary disease and possible alcohol abuse. Isolated elevations of this enzyme may be due to biochemical anomalies rather than the presence of pathology.

Adult↗
PubMed1996

Pharmacological basis for functional selectivity of partial muscarinic receptor agonists.

Muscarinic receptor agonists activate phosphoinositide hydrolysis and adenylate cyclase in Chinese hamster ovary cells transfected with cDNAs encoding the human muscarinic ml and m3 receptors. Whereas carbachol activates similarly both receptor subtypes, 4-[3-chlorophenyl-carbamoyloxy]-2-butynyltrimethyl ammonium chloride (McN-A-343) preferentially activates the m1 subtype over m3, in regard to both phosphoinositide hydrolysis and adenylate cyclase activity. On the other hand, oxotremorine activates phosphoinositide hydrolysis to a similar extent in both cell lines, but it activates preferentially adenylate cyclase in m1 versus m3 receptor expressing cells. Relative to carbachol, both McN-A-343 and oxotremorine activate preferentially phosphoinositide hydrolysis over adenylate cyclase in both cell lines. Prolonged incubation of cells with either carbachol, McN-A-343, or oxotremorine down-regulated the m1 receptors. This was accompanied by a parallel decrease in adenylate cyclase activity, whereas phosphoinositide hydrolysis remained relatively high. Inactivation of the receptors by alkylation with acetylethylcholine mustard, or by blocking with atropine, reduced carbachol-stimulated adenylate cyclase activity more effectively than carbachol-induced phosphoinositide hydrolysis in both m1 and m3 receptor expressing cells. These findings imply that the receptor reserve in these cell lines is greater for phosphoinositide hydrolysis response than for adenylate cyclase response. Yet, the receptor reserve for each of these responses is similar in both m1 and m3 receptor expressing cells. Since the binding affinities of McN-A-343 and of oxotremorine to m1 and m3 receptors are very similar, and since both cell lines contain similar amounts of spare receptors, we propose that the preferential activation of muscarinic m1 over m3 receptor by partial agonists is related to differences in the abilities of the two receptor subtypes to undergo conformational changes following agonist binding. This hypothesis is supported by results showing that the muscarinic m1 but not m3 receptor exhibits two affinity states in a competition binding assay.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗
PubMed1996

Men, women & alcohol: a distinctly unequal & dangerous relationship.

This article illustrates how women who abuse alcohol are at greater risk physically, emotionally and socially than their male counterparts. As a result, I recommend that clinical assessment and underwriting of women, who abuse or have the potential to abuse alcohol, change to reflect the increased risks which these women face.

Adolescent↗
PubMed1994

Verapamil inhibits B-cell proliferation and tumor necrosis factor release and induces a clinical response in B-cell chronic lymphocytic leukemia.

Four B-CLL patients, treated with verapamil for cardiac problems, showed substantial reduction of lymphadenopathy in one, a 3- and 5-year stabilization of B-CLL in two patients, and a dramatic decrease in lymphocyte count, lymphadenopathy and splenomegaly in one stage IV patient. We therefore studied the effects of verapamil on B-CLL cells in vitro. In 13 samples we observed that verapamil strongly inhibited in vitro proliferation of pokeweed mitogen (PWM) stimulated and unstimulated cells. Using a cytotoxic bioassay, we found that verapamil markedly inhibited the spontaneous and PMW-induced release of tumor necrosis factor (TNF) by B-CLL cells. These findings suggest that verapamil may block B-CLL cell proliferation through inhibition of TNF release and thereby may contribute to the management of B-CLL.

Aged↗
PubMed1993

Lymphocytic meningitis as the sole manifestation of Q fever.

A young man who presented with a 3 week history of fever and severe headache accompanied by mild leukocytosis, was found to have lymphocytic meningitis due to Coxiella burnetti. Thus, Q fever can present as lymphocytic (aseptic) meningitis responsive to tetracycline with no evidence of pulmonary involvement.

Adult↗
PubMed1991

Immediate dressing of the burn wound--will it change its natural history?

Thirty deep dermal burns were inflicted on six domestic pigs. On the treated animals, the epidermis was removed and immediately replaced with Omiderm, Xeroform or Mettalin dressings. Burns in which the blister was left intact or not dressed after epidermis removal, served as controls. Macroscopic and microscopic assessment of the healing process was then carried out. Surprisingly, the no-epidermis controls healed somewhat faster than did the untreated controls (those with blister intact). On day 7, 83 per cent of the treated lesions showed initiation of epidermal regeneration, compared with 58 per cent in the no-treatment and no-epidermis controls. All dressing materials were found equal in this model, and differences between control and treatment groups were not significant after 12 days.

Animals↗
PubMed1990

Schizophrenia and fatal self-induced water intoxication with appropriately-diluted urine.

A 31-year-old woman with untreated chronic schizophrenia developed extreme polydipsia which rapidly led to coma and death due to cerebral edema. Hyponatremia (120 mEq/liter) and serum hypo-osmolality (260 mOsm/kg) were associated with marked polyuria (up to 1850 ml/hour) and appropriately low urinary osmolality (90 mOsm/kg) which responded to treatment. This case and few qualifying previous reports which are reviewed support the possibility that pure self-induced water intoxication with no major contribution of inadequate release of antidiuretic hormone may occur, and that extreme polydipsia can sometimes overwhelm normal renal diluting capacity in psychotic patients.

Adult↗