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Biomedical subjects

G W Smith

Publications and source records attributed to G W Smith.

At least 91 records · Page 5Linked to original sources
PubMed1992

Analysis of the agonist activity of fenoldopam (SKF 82526) at the vascular 5-HT2 receptor.

1. The 5-HT2 receptor agonist activity of fenoldopam (SKF 82526) was characterized in the rabbit isolated aorta preparation. 2. Fenoldopam was an agonist at the vascular 5-HT2 receptor with lower affinity and efficacy than the naturally occurring agonist 5-hydroxytryptamine (5-HT). Fenoldopam had an affinity (pKA) of 5.84 +/- 0.04 and efficacy (tau) of 0.57 +/- 0.04, whereas 5-HT had a pKA of 6.65 +/- 0.12 and tau of 2.66 +/- 0.41. 3. The constrictor effects of fenoldopam and 5-HT were competitively antagonized by the 5-HT2 antagonist, ketanserin, with pKB values of 8.81 +/- 0.11 and 8.83 +/- 0.10 respectively. 4. Prior incubation with fenoldopam produced a concentration-related rightward shift of a subsequent 5-HT concentration-response curve. This inhibition was specific for 5-HT since constrictor responses to angiotensin II were unaffected. 5. This study indicates that the D1 receptor agonist, fenoldopam, acts as an agonist at the vascular 5-HT2 receptor, but with an affinity and efficacy less than that of the naturally occurring agonist, 5-HT.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1991

Comparative trial of norfloxacin and macrocrystalline nitrofurantoin (Macrodantin) in the prophylaxis of recurrent urinary tract infection in women.

Eighty-eight women with a history of recurrent urinary tract infection (at least four attacks in the preceding 12 months) were randomized to take either norfloxacin 200 mg at night (45 patients) or macrocrystalline nitrofurantoin 100 mg at night (43 patients) for 12 months. A decrease in the number of symptomatic attacks while taking this prophylaxis was observed in 94 per cent of the patients and this improvement was maintained during the 6 months following the end of prophylaxis in 69 per cent. The mean interval between symptomatic episodes while taking prophylaxis was 7.2-fold and 6.9-fold greater, respectively, than in the 12 months before starting prophylaxis. There were only nine breakthrough infections during 74 patient-years of prophylaxis, four in patients taking norfloxacin (two enterococci, one Staphylococcus epidermidis, one Escherichia coli), and five in those taking macrocrystalline nitrofurantoin (four E. coli, one Klebsiella pneumoniae). Adverse events caused four patients taking norfloxacin (8 per cent) and seven taking macrocrystalline nitrofurantoin (14 per cent) to stop prophylaxis. Norfloxacin had a marked suppressive effect on the coliform part of the faecal flora, with no emergence of resistance. Thus, norfloxacin appears to be an excellent alternative agent to macrocrystalline nitrofurantoin for the prevention of recurrent urinary infections.

Adolescent↗
PubMed1990

Surgical aspects of sclerosing encapsulating peritonitis.

Sclerosing encapsulating peritonitis (SEP) is associated with the administration of beta-blocking agents as well as continuous ambulatory peritoneal dialysis. The predisposing factors in the latter group are recurrent peritonitis, presence of acetate in the dialysate, and antiseptics used during bag exchanges. We report a case of SEP following chronic ambulatory peritoneal dialysis and review the literature on this benign yet potentially lethal condition. Sclerosing encapsulating peritonitis frequently leads to intestinal obstruction, small-bowel necrosis, enterocutaneous fistulas, and malnutrition. There is a high incidence of anastomotic failure when a resection and primary intestinal anastomosis is performed in patients with SEP. Although SEP is not commonly reported in the surgical literature, its importance to surgeons is indicated by the fact that the overall mortality rate is close to 60% in patients with SEP who develop surgical complications.

Adult↗
PubMed1990

FPL 63012AR: a potent D1-receptor agonist.

1. FPL 63012AR is a D1-receptor agonist in the dog kidney, 10 times as potent as dopamine, reducing renal vascular resistance by 20% with an intra-arterial dose of 0.42 nmol kg-1. 2. No prejunctional inhibitory D2-receptor agonist activity was detected in either the isolated ear artery of the rabbit or in the conscious dog as D2-receptor-mediated emesis. 3. Unlike dopamine, FPL 63012AR had no significant agonist activity at alpha 1-, alpha 2-, beta 1- or beta 2-adrenoceptors. 4. FPL 63012AR is a potent inhibitor of [3H]-noradrenaline uptake (Uptake1) into brain synaptosomes, with an IC50 of 29.5 nM, i.e. 9.2 times more potent than dopamine. 5. The ability to block Uptake1, in the anaesthetised dog was confirmed by inhibition of the tyramine-induced pressor and inotropic responses. 6. Intravenous infusion of FPL 63012AR in anaesthetized and conscious dogs (0.3 to 3 nmol kg-1 min-1) reduced vascular resistance and increased blood flow to the kidney which was accompanied by hypotension and tachycardia. 7. It is concluded that FPL 63012AR is an example of a novel class of potent agonists at the D-receptor. Such compounds may have the potential for use clinically in improving renal perfusion and reducing afterload.

Anesthesia↗
PubMed1990

Accessory fallopian tube. A case report.

Accessory fallopian tubes may be found during an evaluation for infertility. The true incidence is unknown but may be as high as 6%. A patient had an ectopic pregnancy in an accessory fallopian tube; its rupture led to emergency surgery. During the next six months, five infertility patients were noted to have accessory fallopian tubes among 100 surgical infertility patients and 398 surgical gynecology patients. The accessory tubes were removed using a microsurgical technique. Three of the five patients had had prior laparoscopy, and their operative reports stated that the pelvis was normal. We suggest a careful evaluation of the pelvis in each patient. If accessory tubes are noted during surgery, one should correct the anatomy to avoid potentially life-threatening situations.

Adult↗
PubMed1989

Eversion of difficult ileostomies by guy rope suture technique.

In the creation of a permanent ileostomy, a fully everted nipple ensures a good fit of the stomal appliance. In normal bowel segment this may not pose a problem, but forceful attempts at eversion in diseased, thickened, and friable bowel may result in damage to the bowel segment. In order to prevent this, we developed a technique that uses the guy rope principle to evert the necessary length of bowel. The technique described in this article may also be used to evert healthy segments of bowel during creation of a permanent ileostomy.

Humans↗
PubMed1988

An introduction to the pharmacologic properties of Dopacard (dopexamine hydrochloride).

Dopexamine hydrochloride (Dopacard) has been developed as a peripherally acting dopamine receptor agonist with afterload reducing properties for use in the acute management of low cardiac output states. Dopexamine hydrochloride is one-third as potent as dopamine in stimulating DA1 receptors but 60 times as potent as a beta 2-adrenoceptor agonist. Unlike dopamine, it is a weak beta 1-adrenoceptor agonist and does not stimulate vascular alpha adrenoceptors. Its stimulant properties at vascular DA1 receptors and at vascular beta 2 adrenoceptors endow it with the ability to improve renal blood flow and to increase cardiac output secondary to afterload reduction. In addition, mild positive inotropic activity arises from stimulation of cardiac beta 2 adrenoceptors, potentiation of endogenous norepinephrine due to uptake-1 blockade, and activation of the baroreceptor reflex. Other features of dopexamine hydrochloride that should enhance its clinical use are lack of arrhythmogenicity and rapid responsiveness to alterations in infusion rate.

Adrenergic alpha-Agonists↗
PubMed1988

Combination chemotherapy including VP-16 for poor prognosis germ cell neoplasms.

Fifteen patients with germ cell neoplasms (9 testicular primary, 4 extragonadal, 2 adult teratoma syndrome) with features indicative of a poor prognosis were treated with chemotherapy followed by surgery. In patients with testicular primary sites, 2 patients have relapsed and all 9 remain alive (median follow-up 36 months). In patients with extragonadal tumors 2/4 are alive without disease, and both patients with the adult teratoma syndrome have died. Combination chemotherapy and surgery can be employed successfully in this subset of patients with germ cell neoplasms.

Antineoplastic Combined Chemotherapy Protocols↗