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Biomedical subjects

S M Barnett

Publications and source records attributed to S M Barnett.

10 recordsLinked to original sources
PubMed1996

Lipid-induced conformational changes of an integral membrane protein: an infrared spectroscopic study of the effects of Triton X-100 treatment on the purple membrane of Halobacterium halobium ET1001.

Exposure of purple membrane from Halobacterium halobium to sublytic concentrations of Triton X-100 results in significant changes in the bacteriorhodopsin (BR) photocycle (Mukhopadhyay et al., 1994). Infrared spectra of purple membrane samples exposed briefly to Triton indicate that this change in protein function accompanies the preferential release of purple membrane glycolipids and squalenes, an association of Triton with purple membrane, and a perturbation of specific lipid headgroup interactions within the membrane. Specifically, the bilayer alterations induced by Triton entail a disruption of lipid headgroup hydrogen bonding in addition to protein conformational changes involving a loss in beta-turn and alphaII-helical structures in BR. We propose that the purple membrane glycolipids and squalenes are critical for the normal functioning of the BR photocycle and that perturbations of these lipids cause the profound photocycle changes induced by exposure to Triton. Lipid reconstitution studies demonstrated that although several of the infrared spectral parameters characteristic of the structural changes induced by Triton were reversed, the photocycle characteristics of BR in native purple membrane were not regained. The observed changes in the vibrational spectra induced by lipid-mediated bilayer perturbations suggest a useful approach for clarifying structure-function relationships of intrinsic membrane proteins exhibiting transmembrane helices.

Bacteriorhodopsins↗
PubMed1984

Lichenoid drug reactions to chlorpropamide and tolazamide.

Many medications, including gold, antimalarials, quinidine, and thiazide diuretics have been implicated in lichenoid drug reactions. Chlorpropamide and tolazamide are sulfonylurea oral hypoglycemic agents, neither of which has previously been implicated in cutaneous lichenoid reactions. We report a case of lichenoid drug reaction related to both chlorpropamide and tolazamide.

Aged↗
PubMed1981

Sequential liver-spleen scanning for documentation of wandering spleen.

An additional case of wandering spleen is reported. A brief review of the etiology of this entity, as well as various findings obtained with nuclear imaging of the spleen, is presented. The authors discuss the relevance of repeated spleen scans to the clinical decision making process. Particular significance is paid to preservation of the spleen to maintain immunologic competence.

Child, Preschool↗
PubMed1980

Antibiotic-associated colitis: a persistent clinical problem.

Examination of this series of 19 patients with antibiotic-associated pseudomembranous colitis revealed that most of the patients were given the antibiotics for trivial reasons. Many different antibiotics were identified as being related to the development of colitis. There were three deaths in this series; two of the 15 patients treated medically and one of the four treated surgically. The efficacy of all diagnostic procedures and medical therapies are discussed, and the role of surgery in treating patients with toxic state, sepsis, or perforation is presented.

Adult↗
PubMed1979

The effects of metoclopramide on postoperative ileus. A randomized double-blind study.

Metoclopramide or placebo was administered postoperatively in a randomized, double-blind fashion to 115 patients undergoing laparotomy. The effect of metoclopramide on postoperative adynamic ileus (PAI) was evaluated. The patients were stratified into two groups: Group A--those with laparotomy without a gastrointestinal anastomosis or ostomy procedure, and group B--those with laparotomy undergoing an anastomosis or ostomy procedure. Metoclopramide reduced nausea and emesis postoperatively. However, the only significant effect on postoperative adynamic ileus was an earlier return to tolerance of solid foods in the patients in Group A.

Adult↗
PubMed1979

The basilic vein fistula for vascular access.

The basilic vein fistula provides reliable vascular access for chronic hemodialysis therapy. Early morbidity includes edema and mild pain. Ischemic complications have not developed in this series. Patency has been excellent in the initial period and no patient has yet developed infection, aneurysm or venous fibrosis, although longer follow-up is necessary. The use of the autogenous basilic vein fistula in patients unsuited for forearm arteriovenous fistulae is supported by these results. Long-term results which would support continued use of this modality would include an expected lower incidence of infection due to the absence of a foreign body and the inherent healing property of viable tissue, and improved long-term patency attributable to the absence of a venous anastomosis.

Adult↗
PubMed1979

Obstructive jaundice secondary to nonbiliary extrahepatic inflammatory disease.

Two patients with persistent obstructive jaundice secondary to chronic pancreatitis and one patient with this picture secondary to a periduodenal fibrosis are reported. The infrequent occurrence of obstructive jaundice in such inflammatory processes is noted and it is suggested that the presence of a circular muscle coat in the common bile duct protects it from inflammatory narrowing. The need for preoperative anatomic evaluation by radiographic techniques is discussed along with methods of therapy.

Adult↗
PubMedDate not supplied

Pyoderma gangrenosum in Crohn's disease: report of a case.

A case of pyoderma gangrenosum of the abdominal wall occurring in a patient with histologically proven Crohn's disease of the colon is described. An aggressive surgical approach (wide excision with delayed skin grafting) resulted in rapid healing of the abdominal wall. Subsequent colectomy through the previously involved abdominal site was accomplished without complication.

Abdominal Muscles↗