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Biomedical subjects

L Cohen

Publications and source records attributed to L Cohen.

At least 289 records · Page 16Linked to original sources
PubMed1991

Oxygen therapy in hemorrhagic shock.

Decreased oxygen delivery and cellular hypoxia are important factors in the pathophysiology of hemorrhagic shock. We studied the effects of 100% oxygen at 1 and 3 ATA (atmosphere absolute) in a severe model of hemorrhagic shock induced by bleeding 50% of the total blood volume in rats. Post-treatment with 100% oxygen at 1 and 3 ATA maintained mean arterial blood pressure (MABP) in hemorrhaged rats at significantly higher values compared to untreated controls (P less than 0.01 at 1 and 3 ATA). Treatment with oxygen attenuated the increase in plasma activities of the lysosomal hydrolase cathepsin D (P less than 0.05 at 1 ATA; P less than 0.01 at 3 ATA). Oxygen at 3 ATA also attenuated the plasma accumulation of free amino-nitrogen compounds (P less than 0.05). Furthermore, hyperoxia prevented the final increase in hematocrit (P less than 0.05 at 1 ATA; P less than 0.01 at 3 ATA). Hemorrhaged rats treated with oxygen also exhibited a significantly longer survival time (P less than 0.01 at both doses), and higher survival rates (50% at 1 ATA and 100% at 3 ATA; P less than 0.05 and P less than 0.01, respectively) than untreated shock rats. No significant effect on any of the above mentioned variables was found in hemorrhaged rats treated with 7% oxygen at 3 ATA (oxygen pressure 0.2 ATA), indicating that all salutary effects can be attributed to oxygen and not to the increased ambient pressure per se. Our results indicate that 100% oxygen in normobaric and hyperbaric conditions exerts important beneficial effects in hemorrhagic shock and may be a useful drug for the treatment of this condition.

Animals↗
PubMed1991

[Slowly progressive apraxia: a MRI and positron tomography in 4 cases].

Four right-handed patients (69, 58 and 68 year-old men; 85 year-old woman) complained of motor difficulties with their left hand (3 cases), or both hands predominant on the left side (1 case). Continuous (1 case) or intermittent (2 cases) myoclonus was noted in the left arm. These disorders gradually progressed for 3 to 10 years. Clinical examination disclosed absence of motor, sensory (except in 1 case), or visual deficit. There were no cerebellar signs, no parkinsonian features (except for mild rigidity in 1 case), and no oculomotor abnormality. On the other hand, neuropsychological examination showed evidence of visuo-constructive apraxia in all cases, dressing apraxia in 3/4 cases and writing impairment in 3/4 cases. There was no amnesia, no aphasia and no intellectual impairment. MRI showed atrophy of the parietal areas, predominant on the right side. A positron emission tomography study was performed in all cases, and twice in 1 case. Cortical energy metabolism was measured using either 18 F-fluorodeoxyglucose or 15 O-Oxygen, to calculate the cerebral metabolic rate of glucose (CMRglu) or oxygen (CMRO2) respectively. Cortical metabolism was significantly decreased in the whole cortex of the right hemisphere in 3 cases, and was also reduced in the cortex of the left hemisphere, significantly in 1/3 studied planes. Moreover, regional metabolic indices (CMRO2 or CMRglu/cortex) showed a significant decrease in both the right and left posterior associative areas (temporo-parieto-occipital cortex), predominantly marked on the right side in 3 cases, indicating bilateral cortical dysfunction. At follow-up, one patient became progressively demented, another had visuo-spatial disorders indicating a lesion of both parietal areas. The relationships of our cases with the slowly progressive apraxia syndrome and with corticobasal degeneration are discussed.

Aged↗
PubMed1990

Induction of interleukin-3 by interleukin-1 in the absence of other exogenous stimuli.

We have previously reported that lipopolysaccharide (LPS) could induce the production of interleukin-3 (IL-3) by mouse spleen cells. In the present study, we show that recombinant human interleukin-1, in the absence of other stimuli, is able to induce the production of IL-3. IL-3 was detected in the supernatants of adult, although neither in young nor in nude mouse splenocytes and was assessed by its capacity to support the growth of the IL-3-dependent FDC-P2 cell line. The presence of IL-3 was antigenically confirmed with a monoclonal anti-IL-3 antibody. Both recombinant IL-1 alpha and IL-1 beta had similar potential for inducing IL-3 production. IL-3 activity was detected in the supernatants of cells cultured in the presence of 100 pg/ml IL-1; maximal IL-3 levels were obtained with 10-30 ng/ml IL-1. Kinetic studies of IL-1-induced IL-3 production indicated that 4-6 days of culture were required for optimal production, whereas 1-2 days were sufficient in cultures stimulated with concanavalin A. Recombinant IL-6 failed to induce significant amounts of IL-3, and TNF alpha induced only weak IL-3 production. GM-CSF but not M-CSF could lead to the appearance of IL-3 in spleen cell culture supernatants. Removal of macrophages decreased the production of IL-3 induced by LPS and GMF-CSF though did not affect the IL-3 production induced by IL-1. This observation suggests that IL-1 production might be an intermediate event in IL-3 production induced by LPS and GM-CSF through the activation of macrophages. IL-3 was detected in culture supernatants of B-cell-depleted splenocytes indicating that T-cells were the source of IL-3. Surprisingly T-cell-depleted populations could also produce IL-3 upon IL-1 stimulation. Preliminary experiments with an autoreactive CD4- CD8- V beta 8+ clone suggested that these cells might also be involved in the described IL-3 production.

Animals↗
PubMed1990

Normal tissue reactions and complications following high-energy neutron beam therapy. II: Complication rates adjusted for censoring.

A dose response analysis was performed on patients at risk for significant radiation injuries following neutron radiotherapy. Complication rates were calculated at various dose intervals using a maximum likelihood method that is formally equivalent to the product limit estimator of survival. The variance of each complication rate was used to weight a logistic regression on log dose. The treatment sites that were analyzed were head and neck, pelvis, thorax, and pancreas. Except for osteomyelitis of the mandible, complications of all types were considered collectively at each site and dose increment since there were too few complications to determine dose response functions for individual types of injuries. The head and neck was observed to be the site with the highest tolerance to radiation whereas the thorax was the most sensitive site.

Dose-Response Relationship, Radiation↗
PubMed1990

Synergism between distinct enhanson domains in viral induction of the human beta interferon gene.

This study demonstrates distinct virus-inducible enhanson properties for three regions of the human beta interferon (IFN-beta) promoter; maximum virus inducibility required syngerism among all three enhansons. Expression of the IRF-1 transcription factor differentially increased the expression of plasmids containing (AAGTGA)4 or PRDIII (-94 to -78) motifs but was inefficient in the induction of the intact IFN-beta promoter. The human T-cell lymphotropic virus type I Tax protein was a strong positive activator of PRDII (-64 to -55)-containing plasmids but was also unable to stimulate the IFN-beta promoter. Induction of the intact IFN-beta promoter linked to a reporter plasmid was achieved in lymphoid and epithelioid cellular backgrounds by a triple transfection with IRF-1 and Tax expression plasmids or a combination of IRF-1 and phorbol ester, indicating that at least two trans-activating events and the association of two proteins on the promoter template are required for IFN-beta activation.

Acetylation↗
PubMed1990

Effects of ethanol on reinforced variations and repetitions by rats under a multiple schedule.

Response sequences emitted by five Long-Evans rats were reinforced under a two-component multiple schedule. In the REPEAT component, food pellets were contingent upon completion of a left-left-right-right (LLRR) sequence on two levers. In the VARY component, pellets were contingent upon variable sequences (i.e., a sequence was reinforced only if it differed from each of the previous five sequences). The rats learned to emit LLRR sequences in the REPEAT component and variable sequences in VARY. Intraperitoneal injections of ethanol (1.25, 1.75, and 2.25 g/kg) significantly increased sequence variability in REPEAT, thereby lowering reinforcement probability, but had little effect on sequence variability in the VARY component. These results extend previous findings that alcohol impairs the performance of reinforced repetitions but not of reinforced variations in response sequences.

Animals↗
PubMed1990

[Double discordance with ventricular septal defect and pulmonary artery hypertension. A study of 21 cases].

This paper reports a retrospective study of 21 children with atrioventricular and ventriculo-arterial discordance, or double discordance, associated with a large ventricular septal defect responsible for pulmonary hypertension. Other associated congenital defects were: atrioventricular block (5 cases), coarctation of the aorta with neonatal cardiac failure (6 cases), tricuspid valve malformations responsible for significant tricuspid regurgitation (11 cases) and right ventricular hypoplasia (1 case). Two children died before any therapeutic intervention, one from syncope related to atrioventricular block and the other after a decision of therapeutic abstention. Three children underwent total correction with one good result (the only case of situs inversus), one late death and one lost to follow-up. The majority of patients (n = 16) underwent initial palliative surgery consisting in pulmonary artery banding occasionally associated with reconstruction of the aortic arch: there was no early mortality but there were 2 late deaths. Of the 14 survivors, 6 are well after a mean follow-up period of 31 months. Eight underwent open heart surgery with 1 operative death, 6 post-operative complete atrioventricular blocks requiring cardiac pacing and 5 poor results due to aggravation or secondary tricuspid regurgitation leading to 1 cardiac transplantation (death) and 2 reoperations for valvular surgery (1 plasty and 1 tricuspid valve replacement). The overall results of this series are poor: high mortality (33 per cent) and equally high morbidity when direct surgery is undertaken. Two major complications are observed: complete atrioventricular block (55 per cent) and regurgitation of the systemic atrioventricular valve (45 per cent), both of which often necessitate invalidating complementary procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed1990

[Stenosis of the pulmonary veins in total anomalous pulmonary venous drainage. Associated or iatrogenic abnormality?].

Obstruction of total anomalous pulmonary venous drainage (TAPVD) is sometimes observed in neonates, usually at the site where the collector drains into the caval system. Stenosis of the pulmonary veins themselves before joining the collector is less common. This was observed in 6 cases of intra- and supracardiac TAPVD; the prognosis is usually very bad due to postoperative pulmonary hypertension (PHT) which is difficult to treat. Three of our cases had TAPVD into the coronary sinus with obstruction presenting at birth. Conventional surgery did not reduce the PHT of the first 2 children because the congenital stenosis of the pulmonary veins was not corrected. In the first case, the pulmonary veins resembled fibrous cords and in the second case, the collector was stenosed at its junction with the coronary sinus. These two children died despite surgery. The third child, however, was cured because the obstruction was diagnosed preoperatively and successfully treated when the TAPVD was corrected. In the other three cases, TAPVD to the superior vena caval system was not obstructed but the pulmonary veins retracted progressively after surgery causing PHT and right ventricular failure. After unsuccessful percutaneous dilatation, reoperation revealed obstruction due to exuberant scar tissue with retraction at the site of anastomosis and (or) reconstruction of the pulmonary veins by incision or enlargement with a pericardial patch. One of these children survived after pneumonectomy of the obstructed lung which relieved reflex PHT of the contralateral lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiocardiography↗
PubMed1990

[Incessant idiopathic ventricular tachycardia in infants].

Reduction of the arrhythmia was obtained in 1 to 5 days, spontaneously (2 cases) of after oral amiodarone (500 to 2000 mg/m2/24 hr) (5 cases) or intravenous flecainide or propafenone in the two most critically ill patients. With the exception of 1 patient who was successfully treated with propranolol for 1 year, amiodarone was prescribed in all cases for 7 to 36 months after reversion to sinus rhythm: 5 children have been taken off treatment and seem to be completely cured 4 to 9 years after withdrawal; the other 3 patients have not had recurrences but have only been treated for 6 to 15 months. One of them has neurological sequellae from a cerebral embolism originating from an atrial thrombus. These results show that incessant ventricular tachycardia in infancy is a serious condition but amenable to medical treatment with high dose amiodarone or, when poorly tolerated, intravenous Class 1c antiarrhythmics for reduction of the arrhythmia, and amiodarone at adequate doses for 2 years to prevent recurrence. With the exception of the rare arrhythmogenic right ventricular dysplasia, the long term prognosis would seem to be excellent and, in general, there would seem to be little need for surgery.

Amiodarone↗
PubMed1990

Computerization: the role of the CEO.

The nature and extent of computerization in Canadian hospitals vary widely. Is this a reflection of the management style of CEOs? In a series of eight interviews, Lynne Cohen found that in most cases, the CEO played a key role in shaping the computerization process.

Canada↗
PubMed1990

Correlation between bone magnesium concentration and magnesium retention in the intravenous magnesium load test.

It has been suspected that Mg retained in the Mg load test is retained in bone--in both hypomagnesaemic and normomagnesaemic Mg deficiency. Bone Mg concentration was therefore compared to the percentage retention of an intravenously administered load of Mg in normomagnesaemic patients at high risk for Mg deficit. We found that the lower the bone Mg concentration the higher the Mg retention in the Mg load test.

Alcoholism↗