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Biomedical subjects

S G Brown

Publications and source records attributed to S G Brown.

At least 37 records · Page 2Linked to original sources
PubMed1989

Laser angioplasty with a pulsed NdYAG laser: early clinical experience.

Since December 1986, 40 laser angioplasty procedures have been performed using the energy from a pulsed NdYAG laser, delivering near infrared light (1064 nm) in 100-microseconds pulses of approximately 300 mJ per pulse, directly through a transparent sapphire tipped device. All patients had total occlusion of the superficial femoral artery and symptoms severe enough to warrant surgery, with ulceration or gangrene in eight, rest pain in 14 and severe claudication interfering with life-style in the others. The device was introduced through an antegrade puncture of the superficial or common femoral artery and laser recanalization was followed by attempted balloon angioplasty in all cases. Occlusions were a median length of 15 cm (range 2-35 cm); ten patients had previously undergone failed attempts at conventional balloon angioplasty and four had occluded femoropopliteal grafts. Thirty-seven legs of 34 patients were treated with an average of 60 J (range 10-235 J) with successful recanalization in 27 and immediate reocclusion in seven. The 20 successful recanalizations have been followed up for up to 24 months (median 7 months) with only one late occlusion at 5 months. Failed recanalization was due to poor transmission by the delivery device in the early part of the series (five cases), repeated passage of the device down a collateral branch (four cases), dissection at the site of previous surgery (two cases) or no apparent reason (two cases). Immediate reocclusion was due to very poor run off in patients with severely ischaemic limbs (three cases) or technical difficulties with balloon dilatation (two cases). Complete symptomatic relief was obtained in all the cases of radiologically successful laser angioplasty. Early surgery was required in one case following reocclusion of the artery when an angioplasty balloon failed to deflate, and one patient suffered a skin reaction thought to be due to inadequate removal of the sterilizing solution. A different sterilizing procedure is now followed. Laser angioplasty can reduce the number of patients requiring bypass surgery and improvements in the device and access methods may reduce the number of untreatable cases.

Adult↗
PubMed1989

Concentration of vitamin B6 and activities of enzymes of B6 metabolism in the blood of alcoholic and nonalcoholic men.

The purpose of this study was to compare concentrations of vitamin B6 compounds and the activities of enzymes that synthesize or catabolize pyridoxal 5'-phosphate in the plasma and erythrocytes of nonalcoholic and alcoholic subjects. Blood was obtained from male nonalcoholics and chronic alcoholics with minimal liver damage and normal hematology. Plasma, erythrocyte, and urinary B6 compounds were analyzed by high performance liquid chromatography, and pyridoxal phosphate was also measured enzymatically. Erythrocyte pyridoxine kinase and pyridoxine phosphate oxidase and erythrocyte and plasma pyridoxine phosphate phosphatases were assayed. Plasma pyridoxal phosphate concentration was significantly lower in the alcoholics (31.3 +/- 3.6 nmol/liter) than in the nonalcoholics (58.7 +/- 7.5 nmol/liter). The concentrations of the other B6 compounds in plasma, erythrocytes, and urine were not different in the two groups. Plasma alkaline pyridoxine phosphate phosphatase activity was significantly higher in the alcoholics (4.05 +/- 0.36 nmol/(h.mg] than in the nonalcoholics (3.01 +/- 0.18 nmol/(h.mg]. The activities of erythrocyte kinase, oxidase, and phosphatases were not significantly different in the two groups. The relationship of plasma pyridoxal phosphate concentration to its metabolites and the activities of the enzymes involved in its metabolism was determined. Plasma pyridoxine phosphate phosphatase activity assayed at pH 9.0 or 7.4 correlated negatively with plasma pyridoxal phosphate concentration. The low pyridoxal phosphate concentration observed in the plasma of the alcoholic subjects may in part be related to increased plasma phosphatase activity.

Adult↗
PubMed1989

Improved comfort and patient acceptance in a novel transdermal nitroglycerin delivery system.

Sixty-three angina patients were recruited to participate in a two-week, randomized, open-label, crossover, multicenter trial to compare patient acceptance of two transdermal nitroglycerin delivery systems, Minitran and Transderm-Nitro (TDN). Patients were enrolled if they had stable angina and had been on a stabilized dose (5, 10, or 15 mg/24 hr) of Nitro-Dur II (ND II) for at least one month before entering the study. Patients with a bias against TDN or with any of the contraindications for transdermal nitroglycerin therapy were excluded. During the two consecutive one-week treatment periods, the patients received their prestudy dose regimen of Minitran and TDN in random order. Patients completed daily diaries, weekly questionnaires, and poststudy patient preference evaluation forms. Of the 63 patients who completed the study, 70% preferred Minitran overall (P less than or equal to 0.001), 24% preferred TDN, and 6% had no overall preference.

Adhesiveness↗
PubMed1988

Rapid, inexpensive quality control of fluorine-18 2-deoxy-2-fluoro-D-glucose preparations using the hexokinase reaction in vitro.

A rapid enzymatic method for determining the purity of 2FDG preparations has been devised. A small aliquot of the preparation is incubated with a hexokinase/adenosine triphosphate/Mg+2 mixture and passed through a Dowex 1 ion-exchange column, which retains the 2FDG-6-phosphate. Another aliquot, without prior incubation, is passed through an identical column and the 2FDG radioactivity is found in the eluant. The criteria for purity are quantitative retention of the 2FDG-6-phosphate on the column and no retention of 2FDG. Comparison of the HK method with thin layer and high performance liquid chromatography assays indicate that the HK method can serve as a rapid, simple and inexpensive alternative to these other methods. It can be used in a routine quality control program and may be easily adaptable to automated 2FDG synthetic methods.

Chromatography, High Pressure Liquid↗
PubMed1986

Microenvironment around the essential cysteine residues in chicken liver fructose-1,6-bisphosphatase as analyzed by ESR spin labelling.

Chemical modification and electron spin resonance spectroscopy (ESR) spin-labelling techniques have been employed to investigate the local environment of the essential sulfhydryl groups of chicken liver fructose-1,6-bisphosphatase. The results demonstrate the presence of two distinct classes of sulfhydryl groups in this enzyme. The first class react preferentially with iodoacetate and its spin-labelled derivative, and this results in an increase in catalytic activity, while the second class react preferentially with N-ethylmaleimide and its spin-labelled derivative, and this leads to a decrease in catalytic activity. The ESR spectral data strongly suggest that the first class of sulfhydryl groups are located in a deep cleft of the enzyme molecule, while the second class of sulfhydryl groups are located in a shallow crevice. The environment of the second class of the sulfhydryl groups appears to undergo a significant change after the modification of the first class of sulfhydryl groups by iodoacetate.

Animals↗
PubMed1986

Laser endoscopy.

Explore the source record for details and available documents.

Endoscopy↗
PubMed1979

Search for human tumour viruses by transfection: uptake of melanoma and Epstein-Barr virus DNA by human cells.

In a model system, consistent transfection of chick embryo fibroblasts (CEF) by DNA from the XC cell line occurred, with recovery of infectious Rous sarcoma virus. The techniques were then applied in attempts to recover possible human tumour viruses. Even with various modifications of the XC technique, DNA from three human malignant melanoma cell lines failed to infect adult or foetal human fibroblasts, although melanoma DNA was taken up into nuclei of target cells. XC DNA did not transfect human foetal fibroblasts and melanoma DNA was ineffective in CEF. DNA from the Raji (Epstein-Barr virus non-producer) and QIMR-WIL (producer) lymphoblastoid cell lines did not transfect human cord blood lymphocytes or amnion cells. These broadly applicable techniques therefore failed to recover EB virus, the putative melanoma retrovirus, or other potential tumour virus.

Animals↗
PubMed1979

Cytotoxicity studies of human melanoma cells and fibroblasts.

In seven human melanoma cell lines and one human fibroblast strain some correlation of resistance to cell killing was found with two bifunctional alkylating agents (melphalan, chlorambucil) and three monofunctional agents (4(5)-(3,3-dimethyl-l-triazeno)imidazole-5(4)-carboxamide (DTIC), methylmethane sulphonate (MMS) and N-methyl-N1-nitro-N-nitrosoguanidine (MNNG), but little cross-resistance was found between these two groups of agents or with cytosine arabinoside (ara-C). In contrast to previous studies with rodent tumours, potentially synergistic (chloroquine, arginine) or antagonistic (ascorbic acid, leucine) compounds did not affect the toxicity of melphalan in a human melanoma cell line. In two melanoma lines DTIC induced patterns of DNA damage (inhibition of semi-conservative synthesis) and repair (strand breaks and repair synthesis) similar to, but not identical with, those induced by the methylating agent MMNG. These results suggest that a methylating species is derived from DTIC but has a different reactivity toward DNA compared with MNNG.

Animals↗
PubMed1975

Plate fixation of iliac shaft fractures in the dog.

In a series of 20 dogs, 23 fractured ilia were reduced and stabilized with a variety of bone plates. The results indicated that fixation was rigid enough for fracture healing and for the patient to be ambulatory soon after surgery. Plate fixation can therefore be recommended as a reliable method of repair in selected fractures of the canine ilium.

Acetabulum↗
PubMed1967

Urea and its formation in coelacanth liver.

Urea occurs in liver of the coelacanth Latimeria chalumnae to the extent of about 1.7 percent by weight. It was determined quantitatively by reaction with 1-phenyl-1,2-propanedione-2-oxime (Archibald reagent) and by measurement of ammonia released upon treatment with urease. Arginase and ornithine carbamoyltransferase, enzymes instrumental in the formation of urea in typical ureotelic vertebrates, occur in homogenates of coelacanth liver. Formed in part by the ornithine-urea cycle, urea may have an osmoregulatory function in the coelacanth as it has in elasmobranchs.

Animals↗
PubMed1966

Uricolytic enzymes in liver of the Dipnoan Protopterus aethiopicus.

The enzymes uricase, allantoinase, and allantoicase have been measured in liver preparations of the African lungfish Protopterus aethiopicus. The levels for these enzymes in lungfish liver suggest that the amount of urea formed in vivo in Protopterus via a uricolytic pathway may be greater than that derived via the Ornithine-urea cycle. The operation of a "purine cycle" in lungfish liver is proposed.

Chordata, Nonvertebrate↗
PubMedDate not supplied

Recanalization of tube overgrowth: a useful new indication for laser in palliation of malignant dysphagia.

Overgrowth of an esophageal prosthesis by cancer is a late complication of insertion which presents a difficult management problem. We have treated 14 such patients; 9 had Celestin tubes and 5 Atkinson tubes in situ for a median of 7 months. The median patient age was 75 years; 3 had squamous cell carcinomas and 11 adenocarcinomas; 12 were at the lowest thoracic esophagus or cardia, and 2 were anastomotic. Eleven tubes were overgrown at the top, two at the bottom only, and one at both ends. Dysphagia was graded from 0 to 4 (0 = normal; 4 = dysphagia for liquids). All patients but one improved with treatment. The median pre-treatment grade was 4 (range, 2 to 4) and post-treatment was 2 (0 to 3). This improvement was significant (p less than 0.01) Wilcoxon-signal rank). Most patients required only one or two endoscopies. The median survival was 9 weeks from first laser session (range, 3 to 36 weeks). We feel these results justify laser treatment in most patients in whom cancer overgrowth causes blockage of an esophageal prosthesis.

Adenocarcinoma↗
PubMedDate not supplied

Incorporating political socialization theory into baccalaureate nursing education.

Political socialization theory explains how an individual develops a political belief system. As the health care system undergoes dramatic changes, nursing faculty should use political socialization theory to enhance the education of student nurses. A political thread can be woven through the nursing curricula, and students can be socialized to the political role. The new generation of nurses must incorporate a political component into their professional role identity. Political socialization theory can guide nursing faculty as knowledge of the political system and political skills are incorporated into nursing curricula.

Curriculum↗