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Biomedical subjects

S Morgan

Publications and source records attributed to S Morgan.

At least 145 records · Page 8Linked to original sources
PubMed1986

Toxic megacolon. An analysis of 70 cases.

The clinical features and outcome of 70 patients treated for toxic megacolon between 1970 and 1984 in five university-affiliated hospitals were determined. There were 35 women and 35 men with a mean age of 39 +/- 0.2 years. Toxic megacolon occurred at the initial episode of colitis in 43 patients (61 percent). Only five patients had a specific colitis: salmonellosis, two; ischemic, two; and pseudomembranous, one. Of the 65 remaining patients with nonspecific colitis, six had to be operated on without delay because of peritonitis. In the remaining 59 patients, toxic megacolon was cured with intensive medical management in nine (15 percent), improved temporarily in 14 (24 percent), and remained unchanged in 36 (61 percent). The postoperative mortality rate was 11 percent for all patients (6/56), 4 percent for patients without perforation (2/50) compared with 27 percent for patients with perforation (4/15). None of the patients who underwent surgery within five days of medical treatment died. When toxic megacolon was complicated by hemorrhage (nine patients) or peritonitis (eight patients), the mortality rate increased to 33 percent and 27 percent, respectively. A one-stage proctocolectomy was performed in 19 patients (32 percent). Of 32 patients in whom the rectum was retained, successful restoration of continuity was possible in only seven (22 percent) within 12 months after surgery. In well-selected patients, a plea is made for rectal preservation to offer an alternative to permanent ileostomy.

Adolescent↗
PubMed1986

Neuronal plasticity in the nigrostriatal system of the rat after unilateral removal of vibrissae.

The vibrissae of rats were shaved from one side of the face daily for 10 days. To see whether or not this treatment had an effect on crossed and uncrossed striatal afferent connections from the midbrain, the tract tracer horseradish peroxidase was applied to the caudate-putamen on day 11. When the tracer was deposited on the side opposite the vibrissae removal, more labeled cells were found in the contralateral substantia nigra than when it was applied on the same side as the vibrissae removal, or placed in animals with intact vibrissae. Unilateral removal of vibrissae did not affect uptake of the tracer by the cells which give rise to the homolateral nigrostriatal projections. These changes in HRP labeling in the crossed projection from the substantia nigra were seen after 10 days of unilateral removal of the vibrissae; i.e., at a time when the animals have had opportunity to learn to compensate for vibrissotomy-induced behavioral asymmetries.

Animals↗
PubMed1986

Apomorphine reverses direction of asymmetry in facial scanning after 10 days of unilateral vibrissae removal in rat: vibrissotomy-induced denervation supersensitivity?

Sensorimotor asymmetries of hemivibrissotomized rats were investigated in an open field. To examine possible behavioral plasticity after unilateral removal of the vibrissae, we compared two groups of rats which had experienced the sensory imbalance for different durations. One group was shaved on one side of the face daily for 10 days before behavioral testing (group 10-Days). The other group was first shaved 4 h prior to the behavioral testing and was sham-shaved for the preceding 10 days (group 4-H). On day 11, the undrugged behavior was examined, and then, one hour later, the behavior induced by apomorphine (0.75 mg/kg, s.c.) was analyzed. In the undrugged state both groups tended to scan the walls of the enclosure with the vibrissae side of the face. After injection of apomorphine, the 4-H group also scanned the walls preferentially with the vibrissae side. In contrast, the 10-Days group reversed the scanning asymmetry under the influence of this drug. That is, animals in this latter group now preferred to scan the walls with the shaved side of the face. These findings are suggestive of a plasticity in dopamine transmission subsequent to unilateral removal of vibrissae. The reversal in direction of asymmetry under apomorphine of the 10-Days group is reminiscent of the apomorphine-induced reversal in sensorimotor asymmetries found after unilateral 6-hydroxydopamine lesion of the substantia nigra, which has been attributed to dopamine receptor supersensitivity.

Animals↗
PubMed1986

Dissociation of crossed and uncrossed nigrostriatal projections with respect to site of origin in the rat.

In the present study we have investigated the relative rostrocaudal position of the neurons in the substantia nigra, which project to the ipsilateral or contralateral neostriatum. The retrograde tract tracer horseradish peroxidase was implanted into the striatum on one side. The substantia nigra, ventral tegmental area and retrorubral area ipsilateral and contralateral to the site of implantation were examined for labeled cells. The distributions of the cells which give rise to the crossed and uncrossed nigrostriatal projections were found to be inverse. More labeled cells were found in the rostral than the caudal part of the substantia nigra ipsilateral to the site of horseradish peroxidase implantation. In contrast, there was a greater likelihood of finding labeled cells in the middle and caudal parts of the contralateral substantia nigra than in the rostral part. Sparse projections from the ipsilateral and contralateral retrorubral area and ventral tegmental area were also found.

Animals↗
PubMed1986

Colonoscopic assessment of radiologic strictures of the colon.

The authors studied 47 patients with radiologic evidence of stricture to determine whether colonoscopy in this situation increased the accuracy of diagnosis and how this procedure might influence patient management. Colonoscopy increased to 81% the diagnostic accuracy, which was established at 38% with the single-contrast enema. Failure of both techniques to establish a precise diagnosis was 19%. From the clinical and radiologic data, surgical exploration for the 47 strictures would have been necessary in 28, not indicated in 9, and indicated solely for diagnostic purposes in 10. The addition of colonoscopy prevented unnecessary laparotomy in 5 (18%) of the first group and in 8 (80%) of the last. The authors conclude that colonoscopy should be complementary to the standard radiologic examination for colonic strictures, especially when carcinoma is suspected or if roentgenography does not provide a definitive diagnosis.

Adult↗
PubMed1986

Selective surgical management of Crohn's disease of the anus.

To establish specific indications for the surgical treatment of perianal Crohn's disease, the authors report their experience with 102 patients (45%) with these lesions in a series of 225 patients with small- and large-bowel Crohn's disease. Ulcerations or fissures were present in 50%, abscesses developed in 32% and fistulas in 53%. More than one type of lesion was present in 59%. One of six patients had no symptoms, in one of five the lesion was etiologically independent of Crohn's disease and one of four patients did not require surgical intervention. Severe pain indicated an abscess that required drainage, and 57% of patients who underwent drainage alone or with an added seton later required fistulotomy to become symptom-free. Primary fistulotomy for abscess achieved complete healing in 71% of cases and fistulotomy also healed in 60% of chronic fistulas for a combined fistulotomy healing rate of 63% when anal Crohn's disease was present and 68% in all patients with Crohn's disease. Anal dilatations with bougies were effective in short stenoses which were present in 7% of cases. Twelve percent of patients required excision of the rectum to be relieved of their symptoms.

Abscess↗
PubMed1985

Natural history of asymptomatic carotid plaque.

In April 1981, a total of 297 carotid arteries were examined prospectively. All patients were asymptomatic and were referred to the peripheral vascular laboratory at Good Samaritan Medical Center, Phoenix, for real-time B-mode ultrasonography. A measurement of luminal area stenosis was determined to be either greater or less than 75%. In addition, the ultrasound echo pattern was used to classify plaque as either calcified, dense, or soft. If, for any reason, the patient or physician felt that carotid endarterectomy should be performed, the patient was dropped from the study. In addition, the use of antiplatelet medication or anticoagulants constituted disqualification. Three groups of patients were observed for three years or until symptoms became apparent. Patients in all three groups with stenosis greater than 75% at the time of initial study were at greater risk than their peers without significant narrowing; however, even those patients with less than 75% stenosis were at greater risk if the associated plaque was less organized, ie, soft. A definite trend toward higher risk is seen in plaques of lower density. Only 10% of those patients with calcified plaque and a significantly stenotic vessel have developed symptoms. In contrast, only three patients of the original 42 with soft plaque and a tight stenosis are still being observed. This study appears to confirm that soft plaques have a greater tendency toward subintimal hemorrhage, ulceration, or primary embolization than more well-organized plaques.

Arterial Occlusive Diseases↗
PubMed1985

Relationship between interhemispheric nigrostriatal projections and the direction of rotational behavior induced by amphetamine.

This experiment dealth with the relationship between the direction of amphetamine-induced turning and the distribution of crossed nigrostriatal projections in the rat. Animals that showed a high degree of asymmetry, as indicated by the consistency and amount of turning behavior elicited by repeated amphetamine administration, were implanted with horseradish peroxidase (HRP) in the striatum either ipsilateral or contralateral to their dominant direction of rotation. Microscopic analysis revealed a relationship between the direction of amphetamine-induced asymmetry and the number of HRP-labeled cells found in the substantia nigra contralateral to the striatum into which the tracer was implanted; i.e., animals with the HRP applied contralateral to their dominant turning direction had more labeled cells in the caudal part of the substantia nigra of the opposite hemisphere than those animals implanted ipsilaterally. There was no relationship between the direction and the number of labeled cells found in the ventral tegmental area and retrorubral area contralateral to the tracer implantation site. Moreover, there was no association between the direction of amphetamine-induced turning and the number of labeled cells found in the homolateral substantia nigra, or ventral tegmental and retrorubral areas.

Amphetamines↗
PubMed1985

Effect of forebrain commissurotomy on recovery from unilateral 6-OHDA lesions of the substantia nigra and circling induced by apomorphine.

We studied the influence of transection of the interhemispheric fiber systems between the anterior and posterior commissures on recovery from turning behavior induced by a unilateral substantia nigra lesion in rats. It has been argued that the crossed nigrostriatal projection is involved in this recovery, and its site of crossing has been suggested to lie within the region split. Animals which received this transection did not differ from controls with respect to time-course and extent of recovery from lesion-induced asymmetries within the 7 postlesion days examined. Additionally, the commissurotomy did not prevent apomorphine-induced contraversive circling.

Animals↗
PubMed1985

Lack of relationship between the direction of operant turning and horseradish peroxidase uptake by crossed nigro-striatal projections.

We examined the effect of training rats to perform an operant turning response on the crossed nigro-striatal projections. Rats were reinforced for circling behavior with water. After 7 days of reinforced circling, the animals were implanted with horseradish peroxidase in the striatum either ipsilateral or contralateral to the direction in which they had been trained to turn. Subsequently, the substantia nigra, ventral tegmental area, and retrorubral area in both hemispheres were examined for labeled cells. This analysis failed to reveal any relationship between the direction of reinforced circling and efferents from these areas to the striatum.

Animals↗
PubMed1985

Morphological response of human rotavirus to ultra-violet radiation, heat and disinfectants.

The morphological damage induced in human rotavirus particles by exposure to ultraviolet (UV) radiation at a wavelength of 254 nm increased progressively with length of treatment. Exposure of the virus in suspension to 9000 ergs/cm2/s was sufficient to remove the smooth capsid layer from 50% of particles after 1 min and from all the virions within 10 min. By this time, the number of stain-penetrated or empty particles increased markedly, along with the appearance of virus-derived debris in the form of disrupted and isolated capsomeres. After treatment for 120 min no intact virus particles were observed. The action of wet (100 degrees C) or dry (60 degrees C) heat resulted in changes similar to those effected by UV radiation, with a rapid loss of viral outer capsid shell from the virions followed by stain penetration and disintegration of particles. Sodium hypochlorite, cetrimide and 70% ethanol induced a rapid loss of the outer capsid layer, but, compared with UV radiation or heat, a slower increase in the number of stain-penetrated particles was noted. This was particularly evident with cetrimide. Chlorhexidine and phenol had effects on virus structure only after extended periods of exposure, whilst glutaraldehyde treatment had little influence on virus morphology. Glutaraldehyde 2% v/v would appear to be most suitable for the disinfection of rotavirus-containing electronmicroscope grids before their examination.

Cetrimonium↗
PubMed1984

Interhemispheric nigrothalamic projections and behavioral recovery following turning behavior induced by unilateral peripheral sensory and motor restriction.

We investigated the relationship between unilateral peripheral lesions plus partial sensory deprivation and interhemispheric nigrothalamic projections. Sensory-motor asymmetries were induced in rats by unilateral ligature of sensory and motor nerves of the forelimbs and hind limbs and partial sensory deprivation (cutting the vibrissae unilaterally and suturing one eyelid). This operation resulted in spontaneous turning which was partially compensated for within the first 5 postoperative days. Sixteen days after the surgery, animals were implanted with horseradish peroxidase in the ventrobasal thalamus of one hemisphere. Brains were processed by the tetramethylbenzidine procedure. Microscopical analysis revealed interhemispheric nigrothalamic projections from the substantia nigra situated ipsilateral but not contralateral to the denervated limbs. The results are interpreted in terms of a reorganization (sprouting) of interhemispheric nigrothalamic projections in response to unilateral peripheral lesions. The lesion-induced behavioral asymmetry and its partial compensation may be one of the determinants of the observed neuronal plasticity.

Animals↗
PubMed1984

Evaluation of children with Down syndrome who participated in an early intervention program. Second follow-up study.

The long-term effects of an early intervention program (EIP) on the motor, cognitive, and adaptive functioning of children with Down syndrome were examined. The cognitive and adaptive functioning was compared with a group of children with Down syndrome who had not participated in an EIP. The motor functioning was compared with the normative sample used in the development of the Bruininks Oseretsky Test of Motor Proficiency. The children were assessed using the Stanford-Binet Intelligence Scale, the Vineland Social Maturity Scale, and either the Bruininks Oseretsky Test of Motor Proficiency or the Gesell Schedules of Motor Development. Results revealed that the children in the EIP earned significantly higher scores (p less than .0005, p less than .05) on the measures of intellectual and adaptive functioning than did the children of comparable age who did not participate in an EIP. The children in the EIP did not show the decline typically seen with age in intellectual and adaptive functioning in children with Down syndrome. The children in the EIP were below expected age levels in gross (77.7%) and fine motor skills (58.3%) but had mean fine motor skill levels that exceeded their mean gross motor skill levels (50%). Based on the results, EIPs for children with Down syndrome appear to provide a foundation for subsequent learning and development.

Child↗
PubMed1983

Effects of reducing sensory-motor feedback on the appearance of crossed nigro-thalamic projections and recovery from turning induced by unilateral substantia nigra lesions.

This experiment addressed the question of whether the increase in interhemispheric nigrothalamic projections, found after unilateral lesions of the substantia nigra (SN), is related to recovery from the lesion-induced sensory-motor asymmetry. We examined the effects of diminished information feedback about the animals' own behavior on recovery from turning induced by unilateral substantia nigra lesions, and the appearance of an increase in number of crossed nigro-thalamic projections. The animals received unilateral 6-hydroxydopamine lesions and were placed in a hammock for the next 7 days. Thus, they were prevented from engaging in turning behavior. They were then implanted with horseradish peroxidase (HRP) in the thalamus ipsilateral to the lesion. No HRP-labeled cells were found in the SN contralateral to the HRP implantation in these animals. In rats, which were allowed 7 days normal interaction with the environment subsequent to unilateral SN damage, labeled cells were found in the undamaged SN when HRP was implanted in the thalamus ipsilateral to the lesion. Animals which were kept in the hammock and subsequently allowed a week of normal interaction with the environment showed the same pattern of recovery from turning behavior as the animals which were allowed to recover normally immediately after the unilateral SN lesion. It was concluded that the relationship between the appearance of the nigro-thalamic projections and the cessation of turning behavior is not fortuitous. Also, it would appear that some form of sensory-motor learning is involved in the recovery of function after unilateral SN lesions. Thus, the results substantiate the idea that these cross-projections form part of a physical basis of recovery from unilateral lesion-induced asymmetries.

Animals↗