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Biomedical subjects

R S Martin

Publications and source records attributed to R S Martin.

At least 55 records · Page 3Linked to original sources
PubMed1989

Voltage dependence and barium sensitivity of colonic K secretion in renal failure.

Net colonic K secretion (JKnet) is increased in rats and humans with chronic renal failure (CRF). To study whether transepithelial potential difference (PD), active transport forces and/or luminal K conductance play a role in this adaptation, experiments were performed in the colon of control, K-adapted, and CRF rats. Under basal conditions the PD in vivo in CRF was greater than in controls and not different from K-adapted rats. JKnet was comparable in vivo in CRF and K-adapted rats and was greater than in controls. Amiloride (10 microM) reduced PD and JKnet in K-adapted and CRF rats to levels comparable to controls. Under in vitro short-circuited conditions serosal-to-mucosal K flux (JKs----m) in distal colon was significantly increased in K-adapted and CRF animals compared with control, whereas barium caused a significant reduction in JKs----m in all groups of animals. The barium-sensitive component of K secretion was greater, however, in the two experimental groups (-0.2 +/- 0.02 and -0.2 +/- 0.07 in K-adapted and CRF animals, respectively, vs. -0.08 +/- 0.02 microeq.h-1.cm-2 in controls, P less than 0.05). However, luminal barium failed to completely inhibit the increase in K secretion observed in the experimental groups. These data suggest that an increase in PD that results in a rise in luminal negativity, stimulation of active transport, and an increase in barium-sensitive K channels and barium-insensitive pathways in apical membrane of distal colon participate in the mechanism by which net K secretion is increased in the large intestine of subjects with CRF.

Amiloride↗
PubMed1989

Renal artery aneurysm: selective treatment for hypertension and prevention of rupture.

Thirty-nine patients with renal artery aneurysm (RAA) were seen over a period of 15 years. Among 20 women and 19 men, 31 were found to have solitary aneurysms, and eight had multiple RAA. Thirty-three patients had diastolic hypertension; nine of them proved to be of renovascular origin. Of the 18 patients who underwent RAA resection, 13 had reconstruction for treatment of hypertension, three had a solitary functional kidney, one had recurrent flank pain, and one had resection for prevention of rupture in a woman of childbearing age. Six of the 18 patients had aneurysmorrhaphy with primary repair or patching, seven had a resection with an aortorenal bypass, and five patients had six ex vivo renal reconstructions with multiple anastomoses. Nephrectomy was performed in two patients with RAA rupture at the time of childbirth and in one patient with hypertension and RAA in a poorly functioning kidney. Reconstructive procedures for documented renovascular hypertension in seven patients resulted in improvement in all cases. Blood pressure improved in only six of 10 patients operated on with hypertension and no lateralization of renovascular studies. Eighteen patients were observed for one to 16 years without surgery, and none experienced rupture. Resection of RAA is indicated to treat patients with renovascular hypertension, patients with hypertension and a solitary functional kidney, and selected patients with severe hypertension and to prevent rupture in women who may become pregnant. Other patients with asymptomatic RAA can be safely observed clinically without serial arteriograms and without fear of rupture.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Large benign virilizing adrenal adenoma.

The young woman described sought evaluation for infertility and was found to have virilization due to a large left adrenal tumor. Further endocrine studies confirmed a syndrome of pure virilization with normal glucocorticoid function. Resection of this apparently benign tumor resulted in regression of virilization, as well as pregnancy. Pure virilization is an unusual manifestation of benign adrenocortical tumors, and adrenal tumors of this size are most frequently malignant.

Adenoma↗
PubMed1988

Continuous i.v. infusion versus multiple bolus doses of metoclopramide for prevention of cisplatin-induced emesis.

Continuous infusion of metoclopramide was compared with bolus dosing in a randomized, double-blind study in 27 patients receiving cisplatin therapy. Hospitalized patients receiving their first course of cisplatin (120 mg/sq m administered i.v. over four hours) were randomized to receive either bolus doses or a continuous infusion of metoclopramide. In the infusion group (14 patients), a loading dose of metoclopramide 3 mg/kg (total body weight) as the hydrochloride salt was infused over one hour immediately before the administration of cisplatin, followed by a continuous infusion of metoclopramide 0.5 mg/kg/hr (as the hydrochloride salt) for 12 hours. Each patient received a total metoclopramide dose of 9 mg/kg over 13 hours. These patients also received five bolus doses of 5% dextrose injection (as placebo) over 15 minutes, with the first dose given one hour before the cisplatin and four more doses at two-hour intervals. In the bolus-dose group (13 patients), metoclopramide 2 mg/kg as the hydrochloride salt was added to each of the bolus doses, while the continuous infusion was a placebo of 5% dextrose injection. All patients also received dexamethasone 10 mg i.v. and diphenhydramine hydrochloride 50 mg i.v. Patients were monitored for 24 hours after initiation of metoclopramide administration for number of emesis episodes and for adverse effects. In the infusion group, 11 of 14 (79%) patients had two or fewer episodes of emesis. In the bolus group, 10 of 13 (77%) had two or fewer vomiting episodes. Mild sedation occurred in both the infusion (79%) and bolus-dose (77%) groups. Despite the use of diphenhydramine, extrapyramidal reactions were seen in one bolus-dose patient and two infusion patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Ruptured abdominal aortic aneurysm: a 25-year experience and analysis of recent cases.

An 8-year experience with treatment of 58 patients with ruptured abdominal aortic aneurysm (RAAA) is reviewed with hospital mortality of 25.9 per cent. Added to a previously reported experience, 115 patients have been treated over 25 years with 33 per cent mortality. Preoperative hypotension, free rupture, venous injury, and massive transfusion were found to be associated with mortality. Interhospital transfer, preexisting coronary or pulmonary disease, known aneurysm, anemia, delay in surgery, and operative time were not found to predict outcome. Some patients are normotensive at presentation, providing an excellent chance for survival when expeditious diagnosis and treatment are carried out. Optimal operative management, complications, and causes of death are discussed. The role of computed tomography (CT) in diagnosis is considered. Elective resection of known aneurysms is the most important factor in reducing deaths from RAAA. The role of regionalization of care is unclear, since some patients cannot be safely transported. However, some evidence for optimal results in specialized centers is presented.

Aged↗
PubMed1987

Primary graft infections.

An amputation rate of 8% to 52% and a mortality rate of 13% to 58% make vascular prosthetic graft infections the most dreaded complication facing a vascular surgeon. In 1978 a randomized prospective double-blind study reported a statistically significant decrease in wound infections in patients treated with prophylactic antibiotics whereas the graft infection difference only approached statistical significance. The present study reviews 2614 arterial prosthetic grafts implanted from January 1975 through June 1986. Twenty-four patients were identified as having a prosthetic graft infection, yielding an overall infection rate of 0.92%. Staphylococcus aureus was the most common organism, occurring in one third of the cases. The most common graft material was polytetrafluoroethylene (PTFE) (33%) followed by Dacron (29%), composite PTFE and Dacron (20%), and umbilical vein grafts (9%). Diabetes was a common factor in one third of the patients. Symptoms of infection were present in 15 patients (63%) within 3 months of operation, with 11 patients showing symptoms within 30 days. The longest interval between operation and onset of symptoms was 48 months. Prophylactic antibiotics were administered to 22 of the 24 patients, but in only 7 of the 22 (29.5%) were they given according to our usual practice. All patients required removal of the infected prosthesis, with limb loss in 17% and death in 17%.

Anti-Bacterial Agents↗
PubMed1986

Nosocomial outbreak of Pseudomonas aeruginosa folliculitis associated with a physiotherapy pool.

Outbreaks of community-acquired Pseudomonas aeruginosa folliculitis have recently been described in association with health spa whirlpools. In February 1984 we detected an outbreak of Pseudomonas folliculitis among hospital staff and patients using a swimming pool in a newly constructed physiotherapy unit. A rash developed in 5 (45%) of the 11 physiotherapists who had used the pool, as compared with 0 of the 17 who had not (p less than 0 005). Pseudomonas folliculitis also developed in 6 (21%) of 29 outpatients and 4 (33%) of 12 inpatients who had used the facility; Pseudomonas infection of a surgical wound also developed in 1 of the 4 inpatients. The epidemic curve was consistent with a continuing common-source outbreak. P. aeruginosa, serotype O:10, was isolated from three physiotherapists, the patient with an infected surgical wound and the pool. A case-control study of pool users did not identify risk factors for infection, although the physiotherapists had spent longer in the pool than had the patients. After hyperchlorination and structural repairs to the pool, no further cases were identified among pool users. This outbreak is the first reported nosocomial outbreak of Pseudomonas folliculitis. Further investigation is needed to determine the risk of serious Pseudomonas infections in hospitalized patients using physiotherapy pools.

Adult↗
PubMed1986

Role of aldosterone in the mechanism of renal potassium adaptation.

Chronic potassium loading results in an adaptive change in renal tubular epithelium which increases the capacity for potassium excretion. The present study was performed to evaluate the role of aldosterone in renal potassium adaptation, since hyperaldosteronism stimulates potassium secretion, and potassium loading increases the production of aldosterone. Experiments were performed in animals with intact adrenal glands, and in adrenalectomized animals (Adx) replaced with basal physiologic amounts of corticosterone, which were not replaced with aldosterone, or were chronically infused with aldosterone to achieve either basal plasma levels or elevated levels. Chronic potassium loading in adrenal intact animals was associated with a statistically significant higher rate of urinary potassium excretion (3.57 +/- 0.30 microEq/min/100 g BW) compared to the control rate (2.54 +/- 0.25 microEq/min/100 g BW, p less than 0.05), during acute infusion of KCl. In potassium loaded Adx animals, with selective replacement of adrenal hormones, the maximum rate of potassium excretion was blunted in the absence of aldosterone, compared to potassium loaded animals with intact adrenal glands. In contrast, when Adx animals were infused chronically with aldosterone, to achieve basal or elevated plasma levels, the maximum rate of potassium excretion was not blunted, although at basal aldosterone levels increased potassium excretion was due, at least in part, to hyperkalemia. These results indicate that the induction of renal potassium adaptation after a week or more of chronic potassium loading is dependent on the action of hyperaldosteronism on renal tubular epithelium.

Adaptation, Physiological↗
PubMed1986

Increased secretion of potassium in the rectum of humans with chronic renal failure.

Previous studies have shown that the intestinal excretion of potassium increases in patients with renal failure and serves to guard against severe potassium retention. It is not known, however, whether the rise in intestinal potassium excretion occurs because of an increase in intestinal potassium secretion or a reduction in potassium absorption. Therefore, studies were performed to evaluate the rate of potassium secretion in the human rectum of controls and subjects with renal insufficiency, using a dialysis bag technique. The results demonstrate that net potassium secretion was increased in subjects with renal failure (-5.2 +/- 0.9 microEq X min-1) compared with the control value of -2.0 +/- 0.4 microEq (P less than .05). This change in intestinal secretion of potassium was shown to be independent of the passive effects of plasma potassium. The rise in potassium secretion, however, correlated directly with an increase in transepithelial potential difference (lumen-negative). Although plasma aldosterone levels were higher in patients than in controls, the scatter of data precludes an assessment of the role of aldosterone in the mechanism of the rise in potassium secretion. These data suggest that augmented intestinal potassium excretion in patients with chronic renal insufficiency is caused by increased net potassium secretion in the large intestine, and highlight the role of the intestine in maintaining potassium balance.

Aldosterone↗
PubMed1986

Failure of potassium adaptation in vivo in the colon of aldosterone-deficient rats.

Prolonged potassium loading results in an adaptive change in colonic epithelium that increases the capacity for potassium excretion. We evaluated the role of aldosterone in colonic potassium adaptation, because potassium loading also increases the production of aldosterone. Experiments were performed in intact animals and in adrenalectomized rats with a high potassium intake replaced over a prolonged period with low physiologic amounts of corticosterone to provide a stable plasma level of 3 to 5 micrograms/dl. Net electrolyte movement and transmural potential difference were measured by an in vivo luminal perfusion technique. Compared with the rate of potassium secretion of -3.6 +/- 0.5 mu Eq/min/gm dry weight in potassium-loaded rats with intact adrenal glands, net secretion was significantly impaired (P less than 0.025) in potassium-loaded adrenalectomized animals with only corticosterone replacement (-1.1 +/- 0.5 mu Eq/min/gm dry weight). The rate in adrenalectomized animals, however, was comparable to that in intact animals receiving a normal potassium intake (0.3 +/- 0.2 mu Eq/min/gm dry weight). In addition, in intact animals prolonged potassium loading significantly increased transmural potential difference to -68 +/- 6 mV (P less than 0.005), compared with that in adrenalectomized, corticosterone-replaced, potassium-loaded animals (-30 +/- 4 mV) and intact animals with a normal intake of potassium (-25 +/- 7 mV). Net sodium absorption was reduced in aldosterone-deficient animals compared with the value in control and potassium-loaded animals with intact adrenal glands. These data indicate, therefore, that potassium adaptation is not induced in the absence of aldosterone and suggest that hyperaldosteronism plays an important role in induction of colonic potassium adaptation.

Adaptation, Physiological↗
PubMed1985

The effect of administration rate on cisplatin-induced emesis.

In an attempt to determine the influence of administration time on cisplatin-induced emesis, 20 adults previously untreated with cisplatin were enrolled into this double-blind study. Twenty patients were randomly assigned to receive high-dose cisplatin (greater than 100 mg/m2) either by a one-hour infusion or by an eight-hour infusion. All patients received antiemetic therapy with metoclopramide 2 mg/kg intravenously one-half hour before cisplatin administration, and 1 1/2, 3 1/2, 5 1/2, and 8 1/2 hours after cisplatin administration. Patients in the eight-hour infusion group experienced significantly fewer emesis episodes than did patients in the one-hour infusion group. The median of emesis episodes in the eight-hour group was one (range, 0 to 2) and in the one-hour group was three (range, 0 to 8). In patients receiving high-dose cisplatin plus metoclopramide, increasing the administration time from one hour to eight hours resulted in a small but significant decrease in emesis episodes. The cisplatin infusion rate should be considered as a variable in cisplatin-antiemetic trials.

Adult↗
PubMed1984

Isolation of Legionella pneumophila from the blood of a patient with Legionnaires' disease.

Legionella pneumophila is rarely isolated from blood cultures. Presently most cases of Legionnaires' disease are diagnosed retrospectively from the results of indirect fluorescent antibody tests, which possess inherent disadvantages. An 81-year-old woman with a history of diabetes mellitus presented symptoms of Legionnaires' disease. Five hours before her death 1.5 mL of blood was withdrawn from a scalp vein and seeded to a culture medium. Following incubation for 3 days L. pneumophila serotype 1 was isolated.

Aged↗
PubMed1984

Thigh claudication due to profunda femoris artery occlusion.

Thigh claudication is usually caused by aortoiliac occlusive disease. A patient with unilateral thigh claudication and normal femoral pulses was found to have isolated profunda femoris occlusion and was successfully treated by profundaplasty. Although this syndrome is rare, a review of vascular anatomy of the thigh and mechanisms of claudication explains its existence.

Arterial Occlusive Diseases↗