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Biomedical subjects

M J Cohen

Publications and source records attributed to M J Cohen.

At least 19 recordsLinked to original sources
PubMed1992

High ligation of the greater saphenous vein for treatment of lower extremity varicosities: the fate of the vein and therapeutic results.

This study was carried out to determine the subsequent fate of the greater saphenous vein and the efficacy of its high ligation along with surgical excision or sclerotherapy of varicosities. From 1988 to 1990, 22 patients underwent high ligation and sclerotherapy, 22 underwent high ligation and varicose vein excision, and four underwent high ligation alone. There were 36 women and 12 men patients. The average patient age was 48. Sixty limbs were scanned by duplex ultrasound pre- and postoperatively to determine the status of the greater saphenous vein. Average follow-up time was 10 months. Patients and surgeons rated the results of therapy for ablation of varicosities and alleviation of symptoms. Surgical complications were evaluated. At postoperative scan, 47 greater saphenous veins (78%) were found to be completely patent, nine (15%) were thrombosed for a short segment (less than 10 cm) and four (7%) were more significantly thrombosed. Those limbs in which high ligation and sclerotherapy were performed had the highest complete patency rate (96%). Patient and surgeon satisfaction was good to excellent in every case. The only complications were three symptomatic greater saphenous vein thromboses. Although follow-up is relatively brief, complete patency of the ligated greater saphenous vein was found in most cases. High ligation allows preservation of a patent greater saphenous vein, which can be used as an arterial conduit at a later date and gives therapeutic results comparable to stripping without the additional morbidity.

Combined Modality Therapy↗
PubMed1992

Event-related brain potentials during orienting to auditory and visual stimulation in spinal cord injured humans.

In intact humans, deprivation of somatosensory and kinesthetic sensations result in significant alterations in perception and information processing. There have been very few studies to discover if the loss of sensation with spinal cord injury (SCI) in humans affects perceptual operations. We hypothesized that the SCI participant would either exhibit arousal, perceptual, and information processing alterations similar to experimentally sensory deprived subjects (who provide the closest human analogue), or that the somatosensory cortex would show reorganization for the processing of other modalities of stimulation. The subjects consisted of 16 paraplegic, 13 quadriplegic, and 22 non SCI controls. Subjects received an auditory orienting task consisting of a 500 Hz tone presented 20 times each at 66, 75, 88, and 101 db and a visual orienting task incorporating light flashes of 115, 123, 131, and 140 lux presented 20 times each. EEG information processing data were recorded from C3 and C4 for 100 msec prior to and 500 msec post stimulation. Information processing variables, analyzed as event-related potentials, indicated that the somatosensory cortex of SCI groups had a flattened response to auditory stimulation. The control group had a significantly larger P2 component. We concluded that these data signified that the somatosensory cortex did not reorganize function in response to chronic deafferentation nor was the SCI subject hyperresponsive to stimulation.

Acoustic Stimulation↗
PubMed1992

Activation, attention, and visuospatial learning in adults with and without a family history of alcoholism.

While recent evidence shows visuospatial information processing deficits to be present in chronic alcoholics, it remains unclear whether such deficits are present prior to alcohol abuse in persons at risk for developing alcoholism. If present, it is also unclear whether the information processing mechanisms underlying these deficits are the same in alcoholics and persons at risk for alcoholism. This study investigated visuospatial information processing psychophysiological activation in adults with and without a family history of alcoholism. Thirty matched nonalcoholics served as participants. Fifteen persons were from families in which at least one biologic parent and one other relative had a history of alcoholism. Another group of 15 persons had no family history of alcoholism. In addition to displaying atypical patterns of learning-contingent physiological activation, participants with a family history of alcoholism displayed visuospatial learning that was significantly poorer than persons with no family history of alcoholism. The learning and physiological activation displayed by the participants with a family history of alcoholism were similar to those displayed by previously studied alcoholics using a similar learning task. The data suggest that visuospatial learning deficits may reflect an antecedent to, rather than a consequence of, chronic alcohol abuse.

Adult↗
PubMed1991

Spatial learning deficits in adult children of alcoholic parents.

This study investigated whether the visuospatial deficits displayed by chronic alcoholics are present in persons at risk for alcoholism. Participants were 34 matched social drinkers, half of whom were children of alcoholic parents and half of whom had no family alcoholism history. Ss with a family history of alcoholism displayed visuospatial learning that was significantly poorer than that displayed by Ss with no family alcoholism history. The learning patterns displayed by those with a family alcoholism history were similar to those displayed by previously studied detoxified alcoholics and young children of alcoholics using a similar learning task. Data suggest that visuospatial learning deficits may reflect an antecedent to rather than a consequence of chronic alcohol abuse.

Adult↗
PubMed1991

Rasch analysis of functional assessment scales: an example using pain behaviors.

Functional assessments associated with rehabilitation frequently rely on scoring systems based upon a limited set of categorical values, arranged in order and intended to represent an underlying performance continuum. Making sense of data generated by these scales is a challenge well met by the Rasch measurement model, which allows detailed investigation of how individuals are likely to perform on a given occasion and indicates whether changes in performance occur in orderly patterns over repeated occasions. Additionally, the Rasch measurement model allows study of the quality of measurement and the degree to which the scoring adequately reflects the underlying, but not directly measurable, continuum. Data gathered at admission and discharge from 330 patients attending a rehabilitation program for chronic low back pain were evaluated using the Rasch measurement model, and the results were contrasted with those from the best available nonparametric technique, ridit analysis.

Back Pain↗
PubMed1990

Digital radiography can reduce scoliosis x-ray exposure.

Digital radiology is a new computerized system of acquiring x-rays in a digital (electronic) format. It possesses a greatly expanded dose response curve that allows a very broad range of x-ray dose to produce a diagnostic image. Potential advantages include significantly reduced radiation exposure without loss of image quality, acquisition of images of constant density irrespective of under or over exposure, and reduced repeat rates for unsatisfactory films. The authors prospectively studied 30 adolescents with scoliosis who had both conventional (full dose) and digital (full, one-half, or one-third dose) x-rays. They found digital made AP and lateral image with all anatomic areas clearly depicted at full and one-half dose. Digital laterals were better at full dose and equal to conventional at one-half dose. Cobb angles were easily measured on all one-third dose AP and on 8 of 10 one-third dose digital laterals. Digital clearly depicted the Risser sign at one-half and one-third dose and the repeat rate was nil in this study, indicating digital compensates well for exposure errors. The study indicates that digital does allow radiation dose to be reduced by at least one-half in scoliosis patients and that it does have improved image quality with good contrast over a wide range of x-ray exposure.

Adolescent↗
PubMed1989

Spatial learning of visual 'nonsense figures' during experimental ethanol intoxication.

The interaction of alcohol and visuospatial learning was evaluated during two experimental sessions. During one session, participants were experimentally intoxicated to obtain a blood alcohol concentration of at least 0.10%. During another session, a nonalcohol placebo was administered. The learning task consisted of a paired-associate paradigm requiring participants to learn the distinct spatial positions of 6 visually presented "nonsense shapes." The visuospatial learning of participants in the placebo condition was generally superior to their learning while intoxicated. However, intercorrelations of performance measures indicated that the relation between alcohol ingestion and performance differences across conditions was not linear.

Adult↗
PubMed1989

Neuropsychologic impairment in children with sickle cell anemia.

In this study, the neuropsychologic functioning of 21 children with sickle cell anemia and 21 sibling controls, age range 7 through 16 years, with no history of neurologic disease, was examined. Outcome measures included tests of intelligence, constructional praxis, memory, and academic learning. On the Wechsler Intelligence Scale for Children--Revised, the sickle cell group had a mean Full Scale IQ of 77.7 (SD 12.4) compared with 94.3 (SD 11.0) for the control group. The profile of test scores was similar for the two groups, with the sickle cell group scoring significantly lower than the control group on almost all cognitive measures. Both groups showed academic achievement to be commensurate with their measured intellectual ability. These results suggest that subtle but significant and widespread neuropsychologic deficits are associated with sickle cell anemia even in the absence of neurologic complications. When and by what process this neuropsychologic impairment is caused needs to be determined.

Adolescent↗
PubMed1989

Sprouts emerging from the dendrites of axotomized lamprey central neurons have axonlike ultrastructure.

We have examined the dendritic and axonal ultrastructure of intact anterior bulbar reticulospinal neurons (ABCs) in the CNS of the larval sea lamprey and compared it with that of the dendrites and neuritic sprouts from ABCs examined 2 months following axotomy. Dendrites and axons of intact ABCs are distinguishable from one another by several ultrastructural criteria: (1) the predominance of microtubules in the dendritic cytoskeleton and neurofilaments in that of the axon, (2) the exclusively postsynaptic status of the dendrites versus the presynaptic status of the axon, and (3) the presence of polyribosomes and large numbers of mitochondria in the dendrites and their respective absence and scarcity in the axon. The ultrastructure of axonal sprouts evoked by axotomy of ABCs 1-1.5 mm from their somata ("intermediate axotomy") in many ways resembled that of intact axons. Axonal sprouts were presynaptic to other neurons, and their cytoskeletons consisted mainly of neurofilaments. They also exhibited some features not seen in either axons or dendrites, such as numerous clusters of small vesicles that were not associated with synapses and, in some cases, close associations with glial elements. We also examined sprouts emerging from the dendrites of ABCs following axotomy within 500 microns of their somata ("close axotomy") and found that such "dendritic" sprouts closely resembled axonal sprouts; they possessed neurofilament-dominated cytoskeletons, were presynaptic to other neurons, and were often associated with glial elements. The dendrites of ABCs undergoing dendritic sprouting retained their normal gross morphology but possessed a mixture of "axonal" and "dendritic" ultrastructural characteristics, exhibiting neurofilament-dominated cytoskeletons while remaining entirely postsynaptic to other neurons. However, there were significantly fewer synapses on the dendrites of axotomized cells than were found on the dendrites of intact ABCs. We conclude that sprouts evoked by axotomy are intrinsically axonal in character whether they originate from the axon stump or from the dendritic tree. Our results also suggest that the materials necessary for axonal regeneration may displace elements of the dendritic cytoskeleton as they are transported through the dendrites to the emerging "dendritic" sprouts following close axotomy.

Animals↗
PubMed1988

Event-related brain potentials in intoxicated and detoxified alcoholics during visuospatial learning.

Event-related potentials and visuospatial learning performance were examined to understand the effects of chronic alcohol use on complex information processing. A total of 18 alcoholic male in-patients in an alcohol treatment program served as participants. Nine persons were seen at time of admission to the program while intoxicated (mean BAC = 18.0 mg/dl). The second group of nine persons was seen detoxified after 4 weeks in the treatment program. Learning consisted of a paired-associate paradigm requiring participants to learn the distinct spatial positions of six, randomly presented "nonsense" shapes. The visuospatial learning performance of the intoxicated alcoholics was superior to that of the detoxified alcoholics. Evaluation of event-related potentials during the visuospatial learning task indicated that while both groups displayed greater right hemisphere amplitudes of P3, P2, N1, and N2-P3 components, the amplitudes of the latter three components were significantly greater in the intoxicated alcoholics. The overall results suggest that compared to the intoxicated alcoholic, the detoxified alcoholic may suffer a disruption in attentional mechanisms related to visuospatial information processing, providing support for a theory that alcohol ingestion serves to balance information processing in the chronic alcoholic.

Adult↗
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↗