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Biomedical subjects

S Morgan

Publications and source records attributed to S Morgan.

At least 19 recordsLinked to original sources
PubMed1992

Time-dependent neuroplasticity in mesostriatal projections after unilateral removal of vibrissae in the adult rat: compartment-specific effects on horseradish peroxidase transport and cell size.

In adult rats the mystacial vibrissae were clipped on one side of the snout, and the influence of this sensory deprivation on crossed and uncrossed striatal afferents from the substantia nigra, ventral tegmental area, and retrorubral area was examined with the horseradish peroxidase tract tracing technique. Unilateral removal of vibrissae was found to affect crossed and uncrossed nigrostriatal projections in a time-dependent manner. One to three days after hemivibrissotomy an apparent neuronal asymmetry was found in the crossed nigrostriatal projection arising in the rostral part of the substantia nigra, with more labeled neurons in the projection to the caudate-putamen on the side of vibrissae removal. This asymmetry resulted mainly from an asymmetry in the subset of nigrostriatal neurons reported to project to the striatal matrix ("dorsal cell type"). In contrast, 4-20 days after hemivibrissotomy reversed asymmetries were found in crossed and uncrossed nigrostriatal projections, with more labeled neurons in the projections to the caudate-putamen of the hemisphere opposite to vibrissae removal (the sensory deprived hemisphere). The asymmetry in the uncrossed projection was found throughout the substantia nigra, but was also most substantial in the projection from its rostral part. The asymmetry in the crossed projection was again restricted to the rostral substantia nigra; interestingly, however, it was limited to the subset of neurons reported to terminate in the striosomes ("ventral cell type"). Evidence was also found for time-dependent changes in size of neurons of the crossed nigrostriatal projections, as well as for changes in striatal afferents from the ventral tegmental area. The time course of these apparent changes in strength of mesostriatal projections is similar to the known time course of recovery from behavioral asymmetries induced by hemivibrissotomy, which is suggestive of a functional relationship between neuronal and behavioral changes. Moreover, the finding of a differential influence of hemivibrissotomy on nigrostriatal afferents to striosomes and matrix is indicative of a functional dissociation of these two systems.

Analysis of Variance↗
PubMed1992

The transoral approach to the cervical spine.

The transoral surgical approach is useful for operating on structures at the base of the brain and the upper cervical spinal cord. For example, this route has been used for resecting spinal tumors and clipping vertebrobasilar aneurysms. In the past, this surgical approach was not advocated due to concerns about exposure and infection. However, the availability of the microscope, computed tomography, computed myelotomography, magnetic resonance imaging and intraoperative radiography as well as more effective techniques have improved the diagnosis of pathology of the craniovertebral junction and surgical performance. An understanding of the operative procedures involved with this approach assists the neuro-science nurse in preoperative teaching and anticipating potential postoperative complications.

Arthritis, Rheumatoid↗
PubMed1992

Plasma inorganic fluoride with sevoflurane anesthesia: correlation with indices of hepatic and renal function.

The biotransformation and plasma inorganic fluoride ion production of sevoflurane (the new volatile anesthetic) during and after surgical anesthesia was studied in 50 ASA I or II surgical patients. Twenty-five additional patients served as controls by receiving isoflurane. Sevoflurane or isoflurane was administered with a semiclosed (total gas flow, 2 L/min O2) circle absorption system for durations of 1.0 to greater than 7.0 minimal alveolar concentration (MAC) hours for surgical anesthesia (sevoflurane MAC, 2.05%; isoflurane MAC, 1.15%). Preoperative and postoperative blood urea nitrogen and creatinine concentrations were determined. Blood samples were obtained during and after anesthesia in both groups for determining anesthetic blood concentration analysis and plasma fluoride level. Plasma fluoride concentrations did not significantly increase during isoflurane anesthesia. Sevoflurane biotransformation produced a mean peak plasma inorganic fluoride concentration of 29.3 +/- 1.8 mumol/L, 2 h after anesthesia, which decreased to 18 mumol/L concentration by 8 h after anesthesia. The peak plasma inorganic fluoride ion concentration correlated with duration of sevoflurane anesthetic exposure. Five patients given sevoflurane had peak levels transiently exceeding 50 mumol/L, and one of these had a history of ingesting drugs potentially producing hepatic enzyme induction. No increases in postoperative levels of creatinine, blood urea nitrogen, direct bilirubin, or hepatic transaminase and no changes in serum electrolyte level occurred in either anesthetic group. Indirect bilirubin concentration increased significantly after sevoflurane anesthesia, but the increase was not of clinical significance (from 0.30 +/- 0.03 to 0.38 +/- 0.06 mg/dL). Indirect bilirubin concentrations did not increase after isoflurane anesthesia; the concentrations reached 0.31 +/- 0.04 mg/dL and did not differ significantly from those found with sevoflurane.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1992

Abdominal wound closure using a running, looped monofilament polybutester suture: comparison to Smead-Jones closure in historic controls.

OBJECTIVE: To determine whether abdominal wound closure with a running, looped monofilament polybutester suture was as effective, inexpensive, and rapid as Smead-Jones closure using the same material. METHODS: Between April 19, 1990 and August 29, 1991, 154 patients undergoing major gynecologic surgery had wound closure using a running, looped monofilament polybutester suture. Controls were 154 patients undergoing similar surgical procedures in the 15 months immediately preceding the study period (January 5, 1989 to April 18, 1990) whose wounds were closed with 0 polybutester using the Smead-Jones technique. All patients received prophylactic cephalosporin antibiotic therapy and external pneumatic leg compression perioperatively. The subcutaneous tissues were not sutured after fascial closure, and the skin was closed with stainless-steel staples. There was no difference between the groups when compared by mean weight, mean ponderal index, number of previous abdominal operations, operative blood loss, or the use of chemotherapy or radiotherapy in the pre- or postoperative period. Both groups had similar rates of complicating medical conditions including insulin-dependent and non-insulin-dependent diabetes mellitus, hypertension, obstructive pulmonary disease, atherosclerotic coronary disease, or peripheral vascular disease. RESULTS: The use of a running closure with looped monofilament polybutester suture in the study patients resulted in a reduction in operating time when compared with controls. The rates of superficial separation and wound infection were similar in both groups. In the study group, there was one minor fascial separation and one wound dehiscence, which occurred when the running suture was inadvertently snipped during debridement of a superficial infection. CONCLUSION: Running closure with looped polybutester is an acceptable, inexpensive, and expeditious method of abdominal wound closure.

Abdomen↗
PubMed1991

Changes in the nigrostriatal projection associated with recovery from lesion-induced behavioral asymmetry.

Possible neuronanatomical changes correlated with recovery from lesion-induced behavioral asymmetry were examined. Rats, with 6-OHDA injected into the substantia nigra (SN) on one side, were either assigned to a group with a 48-hour survival period, or one with a 15-day recovery period. Control groups, without a lesion, were also included. All animals were tested for behavioral asymmetry and, at the end of the survival period, had horseradish peroxidase (HRP) deposited in the caudate-putamen (CPU) ipsilateral to the lesion (right or left CPU in the controls). Both substantia nigrae of all animals were examined for HRP-labeled cells. Animals given a 15-day recovery period had more HRP-labeled cells in the SN ipsilateral to the HRP deposition site than those given a 1-day recovery period. Also animals which showed behavioral recovery had more HRP-labeled cells in their ipsilateral SN than either those which showed no recovery or those which were not given time to recover. Thus, our results suggested that behavioral recovery from lesion-induced asymmetry was associated with an increase in HRP uptake and retrograde transport by the remaining nigrostriatal terminals. Animals which recovered showed the expected decrease in ipsiversive, and increase in contraversive turning with time. Unexpectedly, animals which did not recover exhibited an increase in ipsiversive, and a decrease in contraversive turning with time.

Animals↗
PubMed1991

Preparation, properties, and plasma retention of human hemoglobin derivatives: comparison of uncrosslinked carboxymethylated hemoglobin with crosslinked tetrameric hemoglobin.

Human hemoglobin A has been crosslinked by diisothiocyanatobenzenesulfonate to give a limited number of products in a yield of approximately 70%. The predominant product was crosslinked between subunits within a tetramer and had a Mr of 64,000; no higher Mr species were formed. This product had one crosslink per tetramer located between the NH2 termini of its alpha chains, as established by HPLC analysis, amino acid analysis, Edman degradation, and mass spectrometry. This crosslinked derivative had a slightly increased oxygen affinity [P50 = 9 mmHg (1 mmHg = 133 Pa); P50 for unmodified hemoglobin = 11 mmHg], and the retention time of this derivative in the circulation of rats was 2.9 and 3.3 hr at two hemoglobin concentrations (7 g/dl and 14 g/dl, respectively). The half-life of an uncrosslinked carboxymethylated derivative, which has a low oxygen affinity (P50 = 28 mmHg), was 0.6 and 0.7 hr under the same conditions. Therefore, prolongation of the plasma-retention time of infused hemoglobin is dependent on the crosslinking of the tetramer but independent of the oxygen affinity of the derivative.

Allosteric Regulation↗
PubMed1991

The clinical effects of prolonged treatment of patients with advanced cancer with low-dose subcutaneous interleukin-2 [corrected].

Thirty-five patients with advanced malignant disease have been treated as outpatients with increasing doses (0.1-100 mcg) of interleukin 2 (IL2) by once daily self-administered subcutaneous (s.c.) injection, 5 days weekly for 8 weeks followed by a 4 week observation period. Systemic side effects were not experienced by patients at the 3 lower doses. Three patients required dose reduction from 100 mcg daily because of intolerance (fever, rash, lethargy, nausea and vomiting) and one patient was discontinued because of dyspnoea. We observed immunological effects at the 100 mcg dose (but not at the lower doses). These consisted of (a) a modest sustained lymphocytosis, (b) eosinophilia in six (out of nine) patients and (c) a significant rise in IL2-stimulated peripheral blood lymphocyte activated killer (LAK) cell activity in six (out of nine) patients to a mean of 2.0 times pretreatment levels (P less than 0.01). Two (out of nine) patients with renal cell carcinoma treated with 100 mcg daily had partial responses of duration 4 and 9 months respectively and a further three had disease stabilisation for at least 3 months. Low dose long-term s.c. IL2 is clinically and immunologically active, and in comparison to other IL2 regimens it has minor toxicity and is easy to administer. These characteristics make low dose s.c. IL2 suitable for study in the adjuvant setting.

Adult↗
PubMed1990

The interhemispheric projection from the substantia nigra to the caudate-putamen as depicted by the anterograde transport of [3H]leucine.

The organization of the interhemispheric projections from the substantia nigra to the caudate-putamen was examined after [3H]leucine had been injected into the substantia nigra on one side. There was not a strict correspondence between the regions of termination of the crossed and homolateral nigrostriatal projections. Although the leucine predominantly labeled the lateral parts of the ipsilateral caudate-putamen, terminal labeling was also found in the medial and lateral parts of the contralateral caudate-putamen. The crossed nigrostriatal projection terminated in discrete areas of variable size in the contralateral caudate-putamen. The patterns made by the silver granules in the caudate-putamen contralateral to the [3H]leucine injection appeared to be heterogeneous.

Animals↗
PubMed1990

The basal ganglia-orofacial system: studies on neurobehavioral plasticity and sensory-motor tuning.

We have employed the unilateral removal of the vibrissae as a tool to examine ensuing behavioral changes in relation to concomitant changes in the central nervous system. In this paper we review a series of studies showing that unilateral removal of the vibrissae leads to behavioral asymmetries (e.g., in thigmotactic scanning) from which rats recover over time. Time-related to these behavioral changes we found neuronal alterations in striatal afferents, that is, in uncrossed and crossed projections from the substantia nigra and the tuberomammillary nucleus. The involvement of dopaminergic mechanisms was indicated by results showing that dopaminergic agonists can induce asymmetries in thigmotactic scanning and turning; the direction of these asymmetries was also dependent on time after vibrissae removal. Furthermore, it was shown that endogenous preferential use of one vibrissae side in thigmotactic scanning interacts with the expression of spontaneous and drug-induced behavioral asymmetries exhibited after unilateral vibrissae removal. Neurochemical studies indicated that both unilateral vibrissae removal and unilateral perioral stimulation can have lateralized effects on biogenic amines in the brain. Finally, using electrical stimulation of the substantia nigra, evidence was found for a lateralized and bidirectional interaction between basal ganglia and the orofacial systems, indicating an involvement in mechanisms of motivation and particular stimulation. These results are important from several perspectives. One, they indicate functional links between the orofacial systems and the basal ganglia. Two, they raise the possibility that unilateral removal of the vibrissae can serve as a model (a) to investigate the dynamics of recovery of function after CNS insults, in general, and specifically, (b) to study neuronal plasticity in the nigrostriatal and tuberomammillary-striatal pathways, and (c) to investigate the neuropharmacology of catecholamine systems in the brain.

Animals↗
PubMed1990

Antilymphocyte globulin therapy enhances impaired function of natural killer cells and lymphokine activated killer cells in aplastic anaemia.

MHC-unrestricted cytotoxic lymphocytes, namely natural killer (NK) and lymphokine activated killer (LAK) cells, have been implicated in the regulation of haemopoiesis. To investigate the possible role of these lymphocytes in the pathogenesis of aplastic anaemia (AA), we studied their functions in the peripheral blood mononuclear cells (PBMC) and bone marrow mononuclear cells (BMMC) of patients with AA treated with antilymphocyte globulin (ALG). Before treatment, both NK and LAK activities in the PBMC of 25 patients were low (NK = 1.9 +/- 2.1 x 10(3) LU/l) LAK = 4.7 +/- 3.6 x 10(3) LU/l) compared to normal (NK = 6.0 +/- 3.0 x 10(3) LU/l, LAK = 10.0 +/- 3.5 x 10(3) LU/l) or multiply transfused (NK = 7.8 +/- 6.6 x 10(3) LU/l, LAK = 25.2 +/- 13.6 x 10(3) LU/l) controls. The NK and LAK activities in the BMMC in AA patients were not significantly different from those in PBMC. In all patients with low LAK and NK activities pre ALG there was an increase in activity 2-24 weeks after therapy which eventually reached normal levels and which was maintained for up to 2 years. Analysis of lymphocyte phenotypes in AA patients before treatment showed both significantly low mean proportion and absolute numbers of CD16+ cells compared to normals, which increased after therapy. Changes in MHC-unrestricted cytotoxicity and lymphocyte phenotypes post therapy were not correlated with haemopoietic recovery. These data suggest that ALG treatment can enhance the functions of MHC-unrestricted lymphocytes independently from haemopoiesis. It is unlikely that these cells play a role in the pathogenesis of AA.

Adolescent↗
PubMed1990

Muramic acid is not detectable in Chlamydia psittaci or Chlamydia trachomatis by gas chromatography-mass spectrometry.

By using the powerful separation technique of capillary gas chromatography combined with the selectivity of mass spectrometric detection, muramic acid was not detectable in purified elementary bodies of Chlamydia psittaci Cal 10 (less than or equal to 0.006%) or C. trachomatis serovar E (less than or equal to 0.02%). This confirms previous reports which suggested the absence of a typical peptidoglycan in Chlamydia spp.

Chlamydia trachomatis↗
PubMed1990

Trisomy/tetrasomy 13 in seven cases of acute leukemia.

We report the clinical presentation and the morphologic, histochemical, and immunophenotypic characteristics of seven patients with acute leukemia who had trisomy/tetrasomy 13 as the sole cytogenetic abnormality in their leukemia. Five patients had trisomy 13 at diagnosis of acute leukemia. All five of these patients had undifferentiated leukemias. The sixth patient, who had French-American-British (FAB) type M2 acute nonlymphocytic leukemia (ANLL), and the seventh patient with biphenotypic acute leukemia developed the trisomic clone as a new abnormality late in the course of their disease. A review of the literature revealed 28 previously reported hematologic malignancies with trisomy 13 or tetrasomy 13q as a solitary cytogenetic abnormality. Trisomy 13 appears to represent another rare but nonrandom cytogenetic abnormality in acute leukemia. In our series trisomy 13 is largely associated with acute leukemia with little myeloid or lymphoid differentiation.

Acute Disease↗
PubMed1989

Etiologic heterogeneity in dyskeratosis congenita.

Most patients with dyskeratosis congenita [DC or Zinsser-Cole-Engman syndrome] are males hemizygous for an X-linked recessive mutation. However, one or more autosomal form(s) of DC may exist. We have studied a 6-year-old black girl with the characteristic triad of nail dystrophy, cutaneous and mucosal pigmentary changes, and bone marrow failure. Severe microcephaly, mental retardation, cerebellar hypoplasia, and purple discoloration of the tongue were other manifestations not usually seen in DC. Comparison of our patient's phenotype with that of 5 other sporadic and 10 familial cases of DC in females showed that the autosomal and X-linked phenotypes are not distinguishable in the absence of a suggestive pedigree pattern. Additional cases of DC need to be studied to better elucidate the apparent causal heterogeneity in this syndrome.

Bone Marrow Diseases↗