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Biomedical subjects

S Morgan

Publications and source records attributed to S Morgan.

At least 163 records · Page 9Linked to original sources
PubMed1983

Interhemispheric nigrostriatal projections in the rat: bifurcating nigral projections and loci of crossing in the diencephalon.

The organization of interhemispheric nigrostriatal projections in the rat was studied with (1) a double labeling technique combined with a histofluorescence method for monoamines and with (2) horseradish-peroxidase (HRP) as a tracer. Each animal received an injection of Fast Blue (FB) into the caudate nucleus (NC) of one hemisphere and an injection of Nuclear Yellow (NY) into the NC of the other hemisphere. Brains were processed according to the sucrose-potassium phosphate-glyoxylic acid (SPG) method in order to identify monoaminergic neurons. About 5% of the neurons which were labeled by either of the tracers in the substantia nigra (SN) ipsilateral to the injection site were also labeled in the contralateral SN. Most of these interhemispherically projecting SN-neurons were monoaminergic. A small number of neurons in either SN was labeled with both fluorescent tracers. This suggests that bifurcating, monoaminergic neurons in the SN project to both NC. In the second experiment, rats received a unilateral injection of HRP into NC. After a survival time of several hours the animals were perfused and the brains were processed using benzidine-dihydrochloride. Fibers crossing the hemisphere were found within the massa intermedia of the thalamus and within the inferior thalamic peduncle. The results are discussed with respect to a possible functional role of interhemispheric nigrostriatal connections.

Animals↗
PubMed1983

[Fistulas in diverticular disease of the colon: study of 29 cases].

In analysing 29 patients with diverticular disease of the colon complicated by fistula, the authors encountered four types of fistula: colovesical, colovaginal, coloileal and colocutaneous. The commonest was the colovesical fistula (50%), which was diagnosed by the history and the suggestive cystoscopic findings. Colovaginal fistula was also suspected by the history and the presence of a pelvic mass in hysterectomized patients. Colocutaneous fistulas are demonstrated by fistulography whereas coloileal fistulas, which do not have clinical signs, are discovered only at operation. Surgical treatment, consisting of resection and anastomosis of the involved segment of the colon, is necessary. A one-stage procedure is usually feasible with little morbidity if the delay between the acute phase and the operation is longer than 3 months. When the operation is attempted sooner, the surgeon may have to use more than one stage with a longer period of disability and the possibility of more complications. Because the development of a fistula with diverticular disease seldom needs urgent surgical exploration, the authors recommend 3 months of conservative therapy after the acute phase to allow the local inflammatory reaction to subside so a one-stage operation can be performed.

Adult↗
PubMed1983

High intermuscular anal abscess and fistula: analysis of 25 cases.

Although the majority of anal abscesses and fistulas are of the simple or low variety (intersphincteric or transsphincteric in Parks' classification), some of the simple, but high intermuscular, type are not recognized clinically and are not properly treated because they do not present the usual visible signs. Characteristically, there is no external swelling, induration or opening and there is high extension with a palpable mass or induration above the levator ani. Out of 350 patients with anal abscesses and fistulas treated by the first author, 25 (7%) patients had a high intermuscular abscess. Of these 25, 14 (56%) had a history of anal problems. Eight of these 14 had undergone anorectal surgery previously, and in 3 laparotomy was added, 2 being left with a diverting colostomy. On the other hand, 11 (44%) patients had no previous anal manifestation and 9 of them presented with an acute abscess. All patients had a palpable mass or induration above the levator ani and in all but one a primary opening was found on the dentate line. Fistulotomy was done in 22 of the 25 cases and incision and drainage into the anorectum in the other 3. The authors conclude that for prompt diagnosis and proper treatment the surgeon should be highly suspicious of the condition, have a perfect knowledge of the surgical anatomy of anal abscesses and fistulas and follow three steps: (a) look for a primary opening at the dentate line, (b) pass a cannula from this opening into the cavity or induration and (c) divide the circular muscle and internal sphincter until the upper end of the tract is reached.

Abscess↗
PubMed1982

Ultrasonographic screening for evaluation and follow-up of carotid artery ulceration. A new basis for assessing risk.

Routine ultrasonographic screening and examination of patients with and without specific symptoms of carotid artery disease now provides greater understanding of the natural history of the disease. In one year, 194 ulcers were detected, classified, and followed. No initially asymptomatic ulcer shallower than 2 mm later became asymptomatic, and it is than 2 mm later because asymptomatic, and it is concluded that a trial of antiplatelet therapy in these patients would be inconclusive. More than a third of the initially asymptomatic ulcers from 2 to less than 4 mm in depth gave rise to lateralizing symptoms that required surgery. The effects of antiplatelet therapy in this vulnerable population could be readily followed by ultrasonographic monitoring. All patients with ulcers 4 mm or more in depth were initially symptomatic and so required surgery.

Carotid Artery Diseases↗
PubMed1982

Alkaline reflux gastritis: Roux-en-Y diversion is effective.

Even though controversy persists over the physiopathology of alkaline reflux gastritis, Roux-en-Y diversion is a well-accepted surgical treatment and was used in 23 patients over a 6-year period at the Hôpital St-Luc in Montreal. Of the 23 patients, 21 had complete relief of symptoms. Objective criteria for the selection of patients who would benefit from operation are still to be defined. The authors discuss the physiopathology through an extensive review of the literature.

Adult↗
PubMed1982

The effect of pH on enzyme leakage from isolated mouse heart.

A series of tris-maleate-buffered salt solutions, from pH 6.4 to 8.9 was used to assess the effect of pH on the two hour leakage of creatine kinase (CK) from isolated mouse heart. Leakage was directly related to pH. Hourly enzyme leakage was minimal (less than 0.25%) at pH 6.4, but from pH 6.4 to 8.9, it increased more than 10 fold. The pattern of fractional leakage in the second hour, relative to pH, was approximately sigmoidal in shape, and similar to a monoprotic titration curve. This observation suggests that a single proton binding site may govern myocardial enzyme leakage, under the conditions of this study. Similar observations were made using salt solutions, buffered with tris-HCl, from pH 7.3 to 8.6. The functional group of this putative protective site has a pKa of approximately 7.9, and properties consistent with a nitrogen base of the type found in terminal amino, epsilon-amino, and/or imidazolium groups.

Animals↗
PubMed1980

Learning in surgical and functional hemidecorticate rats: a preliminary study of compensation.

A case is made for the conjoint use of surgical and functional hemidecorticate preparations in the investigation of compensation. Direct comparison of the effects of surgical and functional hemidecortication in rats in an active runway avoidance learning situation is reported. Trials to successively higher avoidance criteria, total avoidance responses, longest runs of consecutive avoidance responses, response latencies and running times are compared. None of these measures reveal differences between the two types of hemidecorticate preparation, although compared with a normal group both hemidecorticate groups show a deficit. The implications of this finding in terms of the compensation issue are discussed.

Animals↗
PubMed1980

Early intervention with Down syndrome children: follow-up report.

This report compares developmental milestones and current intellectual and adaptive functioning of 20 children with Down syndrome who participated in an early intervention program with those of 53 noninstitutionalized children with Down syndrome who did not experience such a program. The children in the former group generally showed earlier acquisition of motor and self-help skills and significantly higher intelligence quotients and social quotients at three to six years of age. Because of certain variables that could not be rigorously controlled in this type of program, the higher functioning cannot be clearly attributed to early intervention. These findings nevertheless are consistent with the hypothesis that early intervention has a beneficial effect and should provide encouragement for further studies.

Child↗
PubMed1979

Regulation of the biosynthesis of aminoacyl-transfer ribonucleic acid synthetases and of transfer ribonucleic acid in Escherichia coli. VI. Mutants with increased levels of glutaminyl-transfer ribonucleic acid synthetase and of glutamine transfer ribonucleic acid.

Spontaneous revertants of a temperature-sensitive Escherichia coli strain bearing a thermolabile glutaminyl-transfer ribonucleic acid (tRNA) synthetase have been selected for growth at 45 degrees C. Among 10 revertants still containing the thermolabile enzyme, 2 interesting strains were found. One strain has a fivefold elevated level of the thermolabile glutaminyl-tRNA synthetase; the genetic locus, glnR, responsible for this effect maps at min 24, far from glnS, the structural gene of the enzyme. In the other strain the levels of tRNA Gln and several other tRNAs are twice as high as in the parental strain; the locus responsible, glnU, maps at min 59.5 on the E. coli map.

Amino Acyl-tRNA Synthetases↗
PubMed1979

Elective correction of intracardiac lesions resulting from penetrating wounds of the heart.

Controversy exists regarding the timing and technique of total correction of traumatic intracardiac lesions. Five patients with penetrating wounds of the heart received emergency treatment aimed at securing normal haemodynamics. No attempt was made to identify intracardiac lesions at this stage. Cineangiography two months to seven years later showed aorto-right ventricular fistulae in all patients, associated in two with aortic cusp laceration and in one with an aorto-left atrial fistula. The surgical approach for aorto-right ventricular fistula was through the right ventricle or aorta. Valvar injuries were treated by plastic reconstruction. All patients showed good clinical results when seen four to 11 years later. Traumatic intracardiac lesions in patients with stable haemodynamics after initial treatment should be operated on electively. The aortic approach is preferable for aorto-right ventricular fistulae. Conservative plastic repair of valvar injuries achieves long-term competence thus avoiding prosthetic replacement.

Adolescent↗
PubMed1979

Regulation of biosynthesis of aminoacyl-transfer RNA synthetases and of transfer-RNA in Escherichia coli.

We have isolated temperature resistant revertants from temperature sensitive E. coli strains containing either a thermolabile glutaminyl-tRNA synthetase or leucyl-tRNA synthetase. Among the revertants which still contained the thermolabile leucyl-tRNA synthetase we found two classes of regulatory mutants (leuX and leu Y) which have elevated levels of this enzyme. The leuX mutation specifies an operator-promoter region adjacent to the structural gene (leuS) for the enzyme. The leuY gene maps away from the leuS gene and codes for a protein. Using these mutants we demonstrated that the levels of leucyl-tRNA are related to the derepression of the leucine and isoleucine-valine operons. Among the revertants which still contained the thermolabile glutaminyl-tRNA synthetase were characterized three classes of mutants, glnT, glnU, and glnR. The glnT and glnU mutants contain elevated levels of tRNAgln, while the glnR mutant possesses elevated levels of glutaminyl-tRNA synthetase. The level of glutamine synthetase, the enzyme responsible for the formation of glutamine, is also derepressed in the glnT and glnR mutants.

Amino Acyl-tRNA Synthetases↗
PubMed1978

Recurrent duodenal ulcer.

In the past 6 years 26 patients underwent operation for recurrent duodenal ulcer after what was considered to be an "adequate" initial operation. In such patients it is necessary first to demonstrate the recurrent ulcer and then to determine its cause. Endoscopy was the best means of confirming the diagnosis. The cause of recurrence was determined by tests for gastric acid secretion; 70% of patients had hyperacidity and 80% had positive results of the Hollander test. Treatment is always surgical but varies depending on the type of initial surgery, the primary cause of recurrence and the condition of the patient. Ten patients underwent vagotomy, 12 had vagotomy with antrectomy and 4 had antrectomy alone. There were no operative deaths but nine (35%) patients experienced 11 significant postoperative complications.

Adult↗