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Biomedical subjects

M J Cohen

Publications and source records attributed to M J Cohen.

At least 73 records · Page 4Linked to original sources
PubMed1988

Activation peaking in intoxicated and detoxified alcoholics during visuospatial learning.

Physiologic activation response patterning, termed activation peaking, and visuospatial learning performance were examined to understand the effects of chronic alcohol use on complex information processing. A total of 18 alcoholic male inpatients in an alcoholism treatment unit served as participants. Nine persons were seen while intoxicated (mean blood alcohol level [BAL] = 18.0mg/dl) at time of admission to the unit. The second group of nine persons were seen detoxified after 4 weeks in the treatment unit (BAL = 0 mg/dl). Skin conductance and heart rate were measured before and during learning. Learning consisted of a paired-associate paradigm requiring participants to learn the distinct spatial positions of six randomly presented "nonsense" shapes. The visuospatial learning of the intoxicated alcoholics was superior to that of the detoxified alcoholics. The physiological patterning of intoxicated alcoholics clearly and correctly tracked their learning performance, while the detoxified alcoholics displayed no clear pattern. The results indicated that the detoxified alcoholic may suffer a disruption in attentional mechanisms related to visuospatial information processing, providing support for theory that alcohol ingestion may serve to balance information processing in the alcoholic.

Adult↗
PubMed1988

Visuospatial learning in elementary school children with and without a family history of alcoholism.

Chronic alcohol abuse has been consistently associated with cognitive deficits in right-hemisphere-mediated visuospatial operations. Recent evidence indicates that visuospatial deficits may be present in alcoholics prior to the onset of chronic heavy drinking, but it remains unclear whether such deficits are present prior to any alcohol exposure in persons at risk of developing alcoholism. The purpose of this study was to investigate visuospatial information processing in young children with and without a family history of alcoholism. Male and female elementary school children (N = 36), ranging in age from 6 to 11 years, served as participants. Of these children, 18 were from families in which one or both biologic parents had a history of alcoholism. The remaining 18 children had no family history of alcoholism or alcohol-related problems. During a single experimental session, each child received a visuospatial paired-associate learning task, requiring the learning of the spatial positions of five low semantic content "nonsense shapes." The learning performance of the children with a family history of alcoholism was significantly poorer than the performance displayed by the children with no family history of alcoholism. The family history positive children required significantly more trials to learning criterion, gave fewer correct responses and committed more errors. Further, an analysis of response-type frequency relative to the learning trials and analysis of response intercorrelations indicated that the pattern of learning displayed by the children with a family history of alcoholism was similar to that displayed by detoxified alcoholics during a similar learning task.

Alcoholism↗
PubMed1988

The pattern of dendritic sprouting and retraction induced by axotomy of lamprey central neurons.

We have investigated some of the factors controlling the distribution of axonal and dendritic sprouting following axotomy of a subset of Muller giant interneurons (anterior bulbar cells or ABCs) in the hindbrain of the larval sea lamprey (Petromyzon marinus). Sprouts originated from different sites in the cell depending on the distance of the axonal lesion from the soma. When the axon was cut close to the soma (within 500 microns), the dendritic tips sprouted profusely, whereas the proximal axon stump showed few sprouts and frequently disappeared entirely. Axotomy further from the soma (1000-1400 microns) resulted in less sprouting from the dendrites and more from the axon stump, with the total amount of dendritic plus axonal sprouting remaining constant. Axotomy at sites distant from the soma (1 cm or more) did not result in dendritic sprouting. No sprouts were ever observed emerging from the soma proper or from the axon stump except at the lesion site. Neuritic sprouts from dendrites and axon were similar in their gross morphology. Sprouts resembled axons rather than dendrites whatever their sites of origin; they followed linear, rostrocaudally oriented paths in the "basal plate" region of the hindbrain. Dendritic and axonal sprouts grew both rostrally and caudally within the brain. Either "close" or "distant" axotomy resulted in the retraction of the dendritic tree and of both dendritic and axonal sprouts by several months postaxotomy. Reaxotomy close to the soma 30 d after a distant axotomy accelerated the onset of this evoked dendritic retraction. Reaxotomy close to the soma also induced sprouting significantly sooner than did close axotomy alone. These results suggest that axotomy close to the soma causes axonal regeneration to be shunted into ectopic locations at the dendritic tips. The emerging sprouts then follow guidance cues appropriate for regenerating ABC axons.

Animals↗
PubMed1988

Dendritic amputation redistributes sprouting evoked by axotomy in lamprey central neurons.

In the previous paper (Hall and Cohen, 1988), we showed that axotomy of anterior bulbar cells (ABCs) in the hindbrain of the larval lamprey results in the sprouting of axonlike neurites from either the end of the proximal axon stump, the dendritic tips, or both, depending on the site of axotomy. Here we show that, unlike axotomy, dendritic amputation (dendrotomy) does not by itself induce sprouting from ABCs. However, dendrotomy does induce sprouting from dendrites in the immediate vicinity of the dendritic lesion in cells that have been previously axotomized. We found that dendrotomy acts primarily to rearrange the distribution of sprouts induced by axotomy rather than serving as an additional stimulus to neurite outgrowth. We propose that (1) dendritic sprouting in ABCs occurs because the dendritic tips become attractive sites for sprout initiation when they are either directly injured (as with dendrotomy) or are situated relatively close to the site of injury (as with axotomy close to the soma), and (2) the axon stump, dendritic stumps, and uninjured dendritic tips of the cell compete to initiate a limited total amount of sprouting induced by axotomy. The probability that a given locus will support sprouting is determined both by its proximity to the nearest lesion site and by whether there are other attractive potential sprouting sites in the cell.

Animals↗
PubMed1987

Histology and ultrastructure of the human flexor tendon sheath.

Twenty human flexor tendons and their sheaths were studied to determine the gross, microscopic, and ultrastructural morphology of their surfaces. Specimens were obtained at the time of autopsy or at the time of reconstructive and reparative surgery. The flexor tendon sheath consists of a noninterrupted layer of parietal synovium reinforced externally at intervals by dense bands of collagen, the annular and cruciform pulleys, and the palmar plates of the respective finger joints. The sheath contents are independently covered by a second similar layer of visceral synovium. These two layers are continuous at the proximal cul-de-sac, the vincula origins, and the tendon insertions. While the synovial cells lining the pulleys and tendons differ quantitatively from those of the membranous portion of the sheath, they are morphologically identical. The presence of a visceral synovial layer covering each tendon may indicate a key role of the synovial cell in tendon healing.

Cytoplasm↗
PubMed1986

Control of neuron shape during development and regeneration.

We have examined the ability of Mueller reticulospinal neurons in the CNS of the larval sea lamprey to sprout following axonal and dendritic injury. Axotomy induces regenerative sprouting exclusively from the axon stump if it occurs at a site distant from the soma in the spinal cord. However, axotomy within the hindbrain at a site close to the soma results in profuse neuritic sprouting from the dendrites. The gross morphology and trajectories of these "dendritic" sprouts resemble those of regenerating axons. Amputation of Mueller cell dendrites (dendrotomy) without axotomy does not result in neuritic sprouting from either the axon or dendrites, indicating that axotomy is specifically required for sprouting to occur. However, dendrotomy is capable of altering the distribution of sprouting in a previously axotomized Mueller cell by inducing sprouting at the site of the dendrotomy lesion. Sprouts of both dendritic and axonal origin tend to follow linear, rostrocaudally oriented paths along or near the ventral surface of the hindbrain. Some sprouts form very large, palmate growth cones on the marginal surface, which in turn give rise to many branches that continue to grow either rostrally or caudally along the surface of the brain. We discuss the possibility that both dendritic and axonal sprouts evoked by axotomy of Mueller neurons are recapitulating initial axonal development during embryogenesis, and that their trajectories are determined by developmental guidance cues persisting in the ventral hindbrain.

Animals↗
PubMed1986

Comparison of electromyographic response patterns during posture and stress tasks in chronic low back pain patterns and control.

Activity of the paraspinals, abdominals, and hip extensor muscles, heart rate, and skin conductance were measured in 13 chronic low back pain patients (CLBP) and 13 controls during static postures and psychological stress. After 10 min of baseline-rest, a subject was tested during standing, 45 degrees bend, maximum bend, posterior and anterior pelvic tilts, sitting, and supine with knees up, followed by mental arithmetic and the cold pressor. The postures were grouped into supported, balanced, and unbalanced categories. Multivariate analyses of variance revealed differences due to posture categories, but not due to group membership. It was concluded that while work is needed to understand normal muscle function during common movements, there is no compelling evidence that back muscle functioning in CLBP patients differs significantly from control subjects.

Adult↗
PubMed1986

The influence of patient insemination on the implantation rate in an in vitro fertilization and embryo transfer program.

The implantation rates and subsequent pregnancy rates in in vitro fertilization (IVF) programs are lower than those currently seen in the normal fertile population. During IVF treatment regimens, intercourse is not allowed and artificial insemination is normally excluded. This trial, involving the deposition of semen in the high vaginal area, was undertaken for evaluation of the influence of sperm in the reproductive tract on subsequent implantation rates. The results show that the implantation rate, as assessed by a rise in the human chorionic gonadotropin levels in inseminated patients, was 53%, compared with 23% in the control group. The implantation rate of 54% in the group who had tubal occlusion or no fallopian tubes was not significantly different from the implantation rate of 50% in the group with patent tubes, which suggests that the site of sperm influence was on the endometrium and that the absence of the fallopian tube has no significant effect upon this influence.

Adult↗
PubMed1985

Repair of subxiphoid incisional hernias with Marlex mesh after median sternotomy.

Median sternotomy is sometimes complicated by a bifid xiphoid process and an incisional (ventral) hernia in the subxiphoid region. Such hernias often recur after primary suture repair. We recently initiated the use of a polypropylene prosthetic mesh to primarily repair subxiphoid incisional hernias. This report details the results of using this material in 14 patients between January 1980 and December 1983. We also discuss the complex anatomy of the xiphoid region.

Adult↗
PubMed1985

Comparing physical and behavior therapy for chronic low back pain on physical abilities, psychological distress, and patients' perceptions.

A treatment-outcome study was conducted to study the impact of behavior and physical therapy on components of the chronic low back pain syndrome. Eighteen patients received behavior therapy and 15 patients received physical therapy. All patients had at least a 6-month history of seeking treatment for chronic low back pain. Prior to treatment patients were assessed in four principal areas of functioning: (1) physical abilities; (2) current physical functioning; (3) psychological and psychosocial functioning; and (4) pain intensity and pain perception. Treatments were conducted in a group (five to eight patients) outpatient setting. Both behavior therapy and physical therapy groups met for 10-weekly sessions, each lasting 2 hr. Behavior therapy was designed to address the environmental, social, and emotional components of the low back pain syndrome as well as the depression and decreased activity that result from chronic low back pain. Physical therapy was based upon traditional rehabilitation theory and was designed to improve low back function. Patients were reevaluated at posttreatment, 6 months, and 1 year. The results showed a general improvement for patients in both groups and a few treatment-specific differences in outcome measures.

Adaptation, Psychological↗
PubMed1985

Physiological and metabolic responses to brief stress in non-insulin dependent diabetic and control subjects.

Eight non-insulin dependent diabetic subjects and eight controls were studied during physical and psychological stress. Physiological measures of heart rate, finger pulse amplitude and blood pressure, as well as metabolic measures of blood glucose, insulin, catecholamines and glucagon were sampled during the experiment. Results indicate substantial physiological arousal during the tasks for both groups, but no changes in blood glucose. Despite signs of mild autonomic neuropathy, the diabetic subjects showed responses similar to the controls on the stress tasks. Overall, this study suggests that diabetic instability does not necessarily follow from physiological activity and stress hormone elevations.

Adult↗
PubMed1985

Candida albicans tenosynovitis of the hand.

Invasive fungal infections of the hand are extremely rare and usually require an immunocompromised host. We report the first known case of Candida albicans tenosynovitis of the hand presenting as a mass in a boy with Buckley's immunodeficiency. Treatment was successful after radical synovectomy of both the flexor and extensor aspects of the hand after he failed to respond to combined amphotericin B and 5-fluorouracil therapy. Fungal tenosynovitis should be considered when swelling and decreased range of motion occur in the hands or digits of an immunocompromised host, especially if pain is not a prominent symptom.

Amphotericin B↗
PubMed1985

Lateral antebrachial cutaneous nerve injury as a complication of phlebotomy.

The lateral antebrachial cutaneous nerve may be injured by attempts at cephalic vein venipuncture because of its anatomic location under the cephalic vein. Multiple attempts at venipuncture using plunging-type action should be avoided. Electric dysesthesias during venipuncture should alert the phlebotomist to possible nerve damage. Primary repair of the injured nerve or its fascicles may be hindered by tension across the antecubital fossa when the elbow is in extension or by the presence of the biceps tendon. As an alternative surgical solution, the neuroma may be resected and the proximal end buried within the substance of the brachialis muscle.

Adult↗
PubMed1984

Alcohol-influenced changes in activation peaking during paired-associate verbal learning.

Activation response patterning, termed activation peaking, was examined to understand the effects of alcohol intoxication on complex information processing. A total of 23 men social drinkers were divided into alcohol and placebo groups: Ns = 10 and 13, respectively. The alcohol group was administered enough alcohol to obtain blood alcohol levels of at least 10 mg/dl. Heart rate and skin conductance was measured before and during paired-associate learning. Learning consisted of a random presentation of eight letter-word pairs followed by the presentation of letters only, with subjects required to remember the associated word. Results showed a clear pattern of peripheral activation related to verbal learning behavior in the alcohol group, with no differences between the groups in verbal learning performance.

Adult↗