Search PubMed⌕ Search

Biomedical subjects

R J Anderson

Publications and source records attributed to R J Anderson.

At least 325 records · Page 18Linked to original sources
PubMed1983

Comparative electroretinograms in argon laser and xenon arc panretinal photocoagulation.

We performed electroretinograms (ERG) on both eyes of 11 diabetic patients before and one month after panretinal photocoagulation for diabetic retinopathy. Each patient had one eye treated with argon laser and the fellow eye treated with the xenon arc photocoagulator. After photocoagulation the ERG was symmetrically reduced unless the retinal area burned with xenon arc was greater than twice the retinal area burned in the fellow eye by the argon laser photocoagulator.

Adult↗
PubMed1983

Total and subtotal replacement of the common bile duct: effect of transhepatic silicone tube stenting.

The effect of silicone tube stenting on the outcome of total and subtotal replacement of the bile duct with autologous vein was investigated in experiments performed in pigs. All but one of the unstented animals developed dense strictures of the extrahepatic ductal system. This complication was abolished by the use of silicone stents passed transhepatically. The vein autografts in the stented animals underwent progressive shortening with elongation of the distal common bile duct so that beyond four months only one suture line was encountered, and no recognisable venous element was detectable on histological examination. Apart from minor dilatation of the intrahepatic biliary tree encountered in some animals, all the surviving stented animals progressed well and had normal serial liver function tests.

Animals↗
PubMed1983

Mechanism of cold diuresis in the rat.

The effect of cold exposure (CE) on renal water excretion has not been clearly delineated. Conscious rats were exposed to decreased ambient temperature (15 degrees C). Forty-five minutes of CE resulted in reversible increases in urine flow and decreases in urine osmolality. The diuresis was not due to a diminished response to vasopressin (VP), as the antidiuresis associated with 500 microU of Pitressin given to water-diuresing rats was comparable at 15 and 30 degrees C. To determine whether the diuresis was due to intrarenal factors, glomerular filtration rate, renal blood flow, sodium excretion, and osmolar clearances were measured and found to be equivalent during control and cold conditions. To determine whether the observed diuresis was due to suppression of endogenous VP, VP-free Brattleboro rats undergoing a constant VP infusion were cold exposed. In these rats, CE was not associated with a change in either urine flow or urinary osmolality. This antidiuretic hormone-mediated mechanism was corroborated by a decrease in immunoassayable VP levels. To determine the mechanism whereby CE suppresses endogenous VP, plasma osmolality and hemodynamic parameters were measured. Although CE was not associated with a change in plasma osmolality, it did result in a significant increase in both mean arterial pressure and cardiac index. Pretreatment of rats with 6-hydroxydopamine prevented both the increase in mean arterial pressure and cold diuresis. We conclude that the diuresis observed upon exposure to 15 degrees C results from nonosmotic suppression of endogenous VP, as a consequence of the increase in mean arterial pressure.

Animals↗
PubMed1983

Mechanisms of escape from desmopressin in the rat.

The mechanism(s) of renal escape from the hydro-osmotic effect of vasopressin is unknown. We therefore studied escape in conscious, unrestrained rats receiving continuous intravascular infusions of 1-deamino-8-arginine-vasopressin (desmopressin) and hypotonic fluid over 5 days. Escape from desmopressin started 8 hours after exposure and was characterized by a progressive increase in urine flow and decreases in urine osmolality and free water reabsorption. When positive water balance was prevented by matching the rate of infusion of hypotonic fluid to urine flow while maintaining the dose of desmopressin constant, escape did not occur. This suggested that water retention, rather than chronic exposure to desmopressin, mediated the escape. To elucidate the mechanism whereby water retention induces escape from desmopressin, urinary prostaglandin E2 excretion was measured and found to be increased concomitant with the onset of escape. Prevention of this increase in urinary prostaglandin E2 excretion with indomethacin resulted in additional water retention and a delay in the onset of escape. During the maintenance of escape, after significant water retention occurred, increases in mean arterial pressure, renal blood flow, and glomerular filtration rate were observed. Renal interstitial solute concentration remained constant through escape. Basal and vasopressin-stimulated collecting tubular and thick ascending limb adenylate cyclase did not differ when control and escape animals were compared. These results suggest that enhanced renal synthesis of prostaglandin E2 facilitates the early phase of escape; later, water retention results in plasma volume expansion with increases in cardiac index, arterial pressure, renal blood flow, and glomerular filtration rate. These systemic and renal hemodynamic alterations may be important in maintaining escape from desmopressin.

Animals↗
PubMed1983

Malignant lymphoma presenting with nonoliguric renal failure.

Nonoliguric renal failure was observed as a presenting complaint in a 14-year-old boy with a malignant lymphoma. The diagnosis was made by a renal biopsy, and the renal failure was treated successfully with peritoneal dialysis while the lymphoma was being treated with radiotherapy.

Acute Kidney Injury↗
PubMed1983

The renal concentrating defect after gentamicin administration in the rat.

The present studies were carried out to delineate the mechanism of the polyuric state and renal concentration defect seen after gentamicin. Gentamicin was given at a dosage of 100 mg/kg/day subcutaneously for either 4 or 5 days to Sprague-Dawley rats and resulted in a reversible, polyuric form of acute renal failure. This nonoliguric acute renal failure was accompanied by significant polydipsia and a renal concentrating defect 11 days after gentamicin. To assess the role of polydipsia in the polyuria and renal concentrating abnormality, water intake was restricted in gentamicin-treated animals to match intake of control animals. Elimination of the polydipsia failed to eliminate the polyuria and to improve the renal concentrating abnormality. Postdehydration plasma vasopressin levels were higher in gentamicin-treated than control animals, suggesting that the renal concentrating defect was nephrogenic in origin. Daily urinary prostaglandin E2 excretion was comparable in gentamicin-treated and control animals. However, indomethacin failed to improve urinary concentrating ability, suggesting that the renal concentrating defect was prostaglandin E2 independent. Finally, depressed postdehydration inner medullary tonicity was found in gentamicin-treated animals In summary, gentamicin administration in the rat was associated with a reversible polyuric form of acute renal failure and a renal concentrating defect. This concentration defect was nephrogenic in origin, independent of polydipsia and prostaglandin E2, and was associated with a decrease in inner medullary tonicity.

Acute Kidney Injury↗
PubMed1983

Heatstroke.

Explore the source record for details and available documents.

Acclimatization↗
PubMed1982

Hyponatremic disorders due to vasopressin excess.

Vasopressin is capable of being stimulated by several nonosmotic factors such as hypovolemia, hypotension, pharmacologic agents and stress. Vasopressin levels of only 1-2 pg/ml are capable of decreasing substantially renal water excretion. If water is ingested or given intravenously in this setting, positive water balance with hypotonicity and hyponatremia of extracellular fluid (ECF) occur. Such dilution of the ECF results in water movement into cells and potential central nervous system complications [3]. Many disorders (see Tab. 1) may be associated with nonosmotic stimulation of vasopressin release. In these clinical settings, judicious administration of free water and monitoring of serum sodium concentration is necessary. A knowledge of clinical conditions associated with vasopressin-mediated water retention may have therapeutic implications as well. Thus, in recent years it has become appreciated that selected pharmacologic agents such as lithium and demeclocycline can impair the water retaining property of vasopressin [26]. Although lithium appears too toxic for routine usage, demeclocycline has proved to be efficacious therapy in some patients with high vasopressin levels and hyponatremia due to the syndrome of inappropriate secretion of antidiuretic hormone who are unable to limit their water intake [9]. More recently, other compounds that selectively antagonize the hydro-osmotic effect of vasopressin are being tested and soon may be available [13].

Adrenal Cortex Diseases↗
PubMed1982

Primary surgical treatment in one hundred ninety-five cases of stage IB carcinoma of the cervix.

Stage IB carcinoma of the cervix may be treated primarily by either radiotherapy of operation. A primary surgical approach was used in 95 patients for the following indications: young age with desire to retain ovarian function (124), pelvic inflammatory disease (33), pregnant or post partum (15), refusal of radiotherapy (11), anatomic problems contraindicating radiotherapy (10), undiagnosed pelvic mass (seven), verrucous tumor (three), mucus-secreting tumor (two), syphilis (one), and previous radiotherapy for Hodgkin's disease (one). Twelve patients had two indications. The surgical procedures were radical abdominal hysterectomy and pelvic lymph node dissection (191) and Schauta-Amreich (radical vaginal) hysterectomy (4). Fourteen patients had serious postoperative complications. The uncorrected 5-year survival rate (95.1% follow-up) was 91.1%. The rationale for recommending a primary surgical approach to selected patients with Stage IB cervical carcinoma is presented.

Adolescent↗
PubMed1982

Dopamine receptor-mediated depression of spinal monosynaptic transmission.

The effects of the dopamine agonists apomorphine, lisuride and lergotrile were evaluated on cat spinal cord monosynaptic transmission by stimulating the dorsal root and recording the ventral root compound action potential. All 3 agonists decreased the area of the monosynaptic response. This effect was prevented by pretreatment with the dopamine antagonists haloperidol and metoclopramide, but not with the alpha-adrenergic antagonist phentolamine. These results suggest the existence of spinal cord dopamine receptors which can modulate motor output.

Action Potentials↗
PubMed1982

The changing role of "second-look" laparotomy in the management of epithelial carcinoma of the ovary.

Thirty-seven of 137 patients had a "second-look" laparotomy in the course of their management of carcinoma of the ovary. Patients were stratified according to three indications: (1) evaluation of disease with intent of stopping therapy, (2) assessment of signs of recurrent or persistent disease with a view to debulking tumor mass and changing chemotherapy, and (3) further tumor resection following cis-platinum combination therapy and determination of further chemotherapeutic agents. "Second-look" laparotomy may be performed after a shorter time interval when combination therapy is given because of the dose-limiting side effects of some of these agents and a more aggressive surgical approach in debulking tumors. At the time of laparotomy, cytologic testing is performed on the peritoneal fluid, and only areas suspicious for malignancy are biopsied. Thirteen percent of patients with no evidence of disease at "second-look" laparotomy developed recurrent disease. Twenty-nine percent of patients classified as clinically free of disease had malignancy present at the time of operation. Continued routine use of "second-look" laparotomy after appropriate chemotherapy is recommended.

Adenocarcinoma↗
PubMed1982

Assessment of failures of cryosurgical treatment in cervical intraepithelial neoplasia.

The overall recurrence rate in 166 patients treated with cryosurgery is 10.8%. Recurrent cervical intraepithelial neoplasia is much more common in patients with severe dysplasia. Failures are commonly due to one of four factors. First, cryosurgery is to be used only after adequate colposcopic assessment and a negative endocervical curettage. Cryosurgery is a safe, effective treatment in selected patients, but consideration of surgical management should be given in the older patient who has completed childbearing, particularly those with severe dysplasia or carcinoma in situ. A full 7-minute freeze with optimum application of the cryoprobe to the full affected surface is essential. Careful follow-up of these patients is mandatory. The majority of failures occur within the first 12 months and probably represent persistent rather than recurrent diseases.

Acute Disease↗
PubMed1982

Rat phenol sulfotransferase. Assay procedure, developmental changes, and glucocorticoid regulation.

Phenol sulfotransferase (PST) catalyzes the sulfate conjugation of phenolic monoamines and phenolic drugs. It has been difficult to measure PST activity in tissue homogenates accurately because of the presence of potent endogenous PST inhibitors. Optimal conditions were determined for the assay of rat PST in very dilute tissue homogenates. These conditions negated the effects of endogenous enzyme inhibitors. Apparent Km values for 3-methoxy-4-hydroxyphenylglycol, the sulfate acceptor substrate used, were 0.15, 0.14, and 0.02 mM for liver, kidney, and brain homogenates respectively. Apparent Km values in the same tissues for 3'phosphoadenosine-5'phosphosulfate, the sulfate donor, were 0.11, 0.07, and 0.07 microM respectively. Rat PST activity expressed per mg protein increased 6.3-fold in the liver, 6.6-fold in the brain, and did not change in the kidney between birth and 10 weeks of age. There was a 5-fold increase in kidney PST activity in both adrenalectomized and sham-operated Sprague-Dawley rats after treatment with dexamethasone (7 mumoles/kg daily for 3 days). Brain enzyme activity was unchanged and liver PST activity increased only 41% during 72 hr of daily treatment with dexamethasone. Basal enzyme activities in all three tissues were no different in adrenalectomized and sham-operated animals. The increase in rat kidney PST activity in response to dexamethasone was dose dependent, and treatment of animals with cycloheximide, a protein synthesis inhibitor, blocked the elevation of kidney PST activity after dexamethasone. Treatment of eight inbred and two outbred rats strains with dexamethasone resulted in striking increases in renal PST, smaller increases in liver PST, and no changes in brain enzyme activity in all ten strains.

Adrenalectomy↗