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Biomedical subjects

M J Cohen

Publications and source records attributed to M J Cohen.

At least 55 records · Page 3Linked to original sources
PubMed1994

Neuropsychological impairment in children with sickle cell anemia and cerebrovascular accidents.

Neuropsychological functioning of children with sickle cell anemia (HbSS) who have experienced a single stroke has not been extensively investigated. In this study, the neuropsychological functioning of 10 children with HbSS who were receiving transfusion therapy following stroke with no identifiable recurrence was examined. The patients were subgrouped into children with only left hemisphere stroke (LCI), N = 4, and those with only right hemisphere stroke (RCI), N = 6. Results indicated that these youngsters experienced significant impairments of cognitive functioning following stroke. It was found that the LCI and RCI children tended to perform more like adult stroke patients than what has been typically reported in children with infantile hemiplegia. These findings support the need for periodic neuropsychological evaluation following stroke in order to identify patterns of higher cortical dysfunction and assist in the development of appropriate rehabilitation and special education programs. Further, pediatricians, child neurologists, and psychologists who care for these children must act as strong advocates on their behalf in order to ensure that they receive appropriate rehabilitation and the special education services necessary for maximal recovery and future educational success.

Adolescent↗
PubMed1993

Mood variability in normal subjects on lithium.

To investigate the effect of lithium carbonate on normal volunteers' moods, we randomly assigned 30 subjects to 5 weeks each of placebo and lithium treatment with crossover at midstudy. Lithium levels were maintained during the treatment period at a mean serum level of 0.54 mEq/L. All subjects completed visual analogue mood scales (VAMS) daily throughout the study period; segmented visual analogue scales (SVAS) measuring mood, anxiety, and energy and the Profile of Mood States (POMS) were completed weekly at testing sessions. Neither mean mood nor mood variability as assessed by the delta square (mean square successive difference) differed between placebo and lithium conditions. Segmented visual analogue scale mood ratings were highly correlated with the VAMS and similarly showed no difference between conditions. The self-rated mood variability, however, declined significantly in both experimental conditions as a function of time on study. None of the POMS factors differed between placebo and lithium conditions. These data suggest that lithium, in modest doses administered over 5 weeks, does not have a substantial mood-stabilizing effect in normal subjects.

Adult↗
PubMed1993

Two-point discrimination thresholds in spinal cord injured patients with dysesthetic pain.

We questioned whether deafferentation following SCI would result in an increase in somatic sensitivity possibly due to cortical reorganization. Dysesthetic pain syndrome (DPS) below the level of a spinal cord injury (SCI) is a common complication. We hypothesized that DPS patients would show increased cortical reorganization because of high levels of sensory stimulation following injury. Sixteen dysesthetic pain SCI patients, 15 SCI patients without pain, and 16 control subjects were examined for two-point discrimination thresholds (2PDT) of the forearm, neck, and spine. The SCI pain group had significantly smaller 2PDTs than either SCI no pain or control groups, particularly over the neck and spine. The SCI pain group had a significant inverse correlation between perceived degree of pain (visual analogue scale) and 2PDT in the spinal skin area. The findings indicate that SCI patients with severe DPS have a higher sensitivity to somatosensory stimuli, particularly in skin areas with projections to primary somatosensory cortex areas adjacent to the deafferentated region. The increase in 2PDT may be due to an increase in the size of the somatosensory cortical areas allotted to the corresponding skin areas.

Adult↗
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

Determination of C1-C4 alkanes by ion mobility spectrometry.

Flight instrumentation for the analyses of extraterrestrial environments must often perform under severely restricted conditions. Often, the detection and identification of a multitude of chemical species is required to fulfill the scientific objectives of the mission. It is therefore important that the analytical instrumentation have universal response. The gas chromatograph-ion mobility spectrometer (GC-IMS) has the potential to provide the sample separation, identification and sensitivity necessary for a successful analysis. However, the IMS has poor sensitivity for the C1-C4 alkanes. The abundance of these molecules at various extraterrestrial sites is often of great importance to exobiologists. This study focuses on optimizing IMS sample ionization mechanisms for the C1-C4 alkanes and other hydrocarbons of interest to exobiology.

Alkanes↗
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↗