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Biomedical subjects

R J Anderson

Publications and source records attributed to R J Anderson.

At least 289 records · Page 16Linked to original sources
PubMed1985

Acute hypercapnic acidosis diminishes renal water excretion in conscious dogs.

The effects of acute hypercapnic acidosis (PaCO2 = 52 +/- 2 mm Hg, pH = 7.23 +/- 0.01) of 40-80 min duration on renal water excretion and circulating vasopressin were examined in conscious dogs during stable diuresis in protocols either with hypotonic water loading (n = 6) or in the euvolemic state (n = 7). The mean arterial pressure increased (p less than 0.05) during acute hypercapnic acidosis in euvolemic dogs, but was unchanged in the dogs given a water load. However, the free water clearance decreased (p less than 0.05), and urine osmolality increased during acute hypercapnic acidosis in both water-loaded and euvolemic dogs despite stable renal hemodynamic function and osmolar clearance. Plasma vasopressin concentrations increased (p less than 0.05) during hypercapnic acidosis in euvolemic but not in water-loaded dogs. The plasma renin activity increased with hypercapnic acidosis in both water loaded and euvolemic dogs. These observations indicate that acute hypercapnic acidosis results in diminished renal water excretion and increased urine osmolality in conscious dogs.

Acidosis, Respiratory↗
PubMed1984

Generic alternatives in general practice.

Using a standard analysis of one month's prescribing in a general practice we showed a potential saving of 8.8% (pounds 883.22) of the net cost of ingredients through substituting exact generic alternatives. Our results confirm the possible reduction in cost of drugs to the National Health Service by the use of generic substitution as suggested in the Greenfield report. Although substitution was theoretically available in most therapeutic classes, two thirds of the potential savings pertained to two classes, preparations acting on the nervous system and preparations acting on the cardiovascular system and diuretics. Of the prescriptions (31%) with potential generic alternatives, less than three quarters were actually available.

Aged↗
PubMed1984

Human platelet phenol sulfotransferase: stability of two forms of the enzyme with time and presence of a racial difference.

Thermolabile (TL) and thermostable (TS) forms of human platelet phenol sulfotransferase (PST) were measured over various periods of time. TL PST was assayed with dopamine as the substrate and TS PST was measured with phenol and with p-nitrophenol. Levels of TL and TS PST from the same subjects did not change significantly over 1 day, 1 week, 4 weeks, and 8.5 months. Interassay coefficients of variation of PST activities over 3-4 weeks measured in samples from 8-12 subjects with dopamine, phenol and p-nitrophenol were 13.96%, 13.60% and 13.30%, respectively. There was a significant correlation between PST activity measured in the same samples with phenol and with p-nitrophenol (r = 0.946, n = 18, p less than 0.0001). TS PST activity measured with p-nitrophenol was significantly higher (p less than 0.0001) in platelets from 51 black subjects than the level of TS PST in samples from 52 white subjects (0.72 +/- 0.06 vs 0.42 +/- 0.04 units/10(8) platelets, respectively; mean +/- SEM). These results demonstrate the 'stability' of the levels of both forms of the enzyme with time. They also point out the usefulness of a reproducible assay for the detection of a racial difference in the levels of TS PST.

Adult↗
PubMed1984

Transport of fluorescein in the ocular posterior segment in retinitis pigmentosa.

The function of the blood-retinal barrier was assessed by vitreous fluorophotometry in 12 patients with various genetic types of retinitis pigmentosa and in 11 normal subjects. The measurements were corrected to minimize the effect of artifacts. We evaluated the inward penetration of fluorescein sodium across the blood-retinal barrier and determined the outward permeability coefficient for fluorescein by interpreting the data with a pharmacokinetic computer model. Patients with retinitis pigmentosa had increased inward permeability and decreased outward permeability to fluorescein in comparison with values of normal subjects.

Adolescent↗
PubMed1984

Total lymphoid irradiation therapy in refractory rheumatoid arthritis. Fifteen- to forty-month followup.

Twelve patients with refractory rheumatoid arthritis were treated with total lymphoid irradiation (TLI) to a total cumulative dose of 3,000 rads. Post-TLI morbidity/mortality included 8 patients with xerostomia, 4 with weight loss of greater than 10 kg, 3 with loss of 4 or more teeth, 3 with herpes zoster, 4 with bacterial infection that was fatal in 2, 3 with hypothyroidism, 1 with cutaneous vasculitis, and death from myocardial infarction in 1 patient and cardiorespiratory arrest in another. Ten of the patients were reevaluated 15-40 months (mean +/- SE, 30 +/- 2) after completion of TLI, and significant improvement was noted in several disease parameters including number of swollen joints, duration of morning stiffness, and 50-foot walking time. Blood lymphopenia and a decrease in helper T cells (T4) were also noted. These data suggest that changes in immunoregulation induced by TLI can produce longlasting alterations in rheumatoid arthritis, although adverse effects may limit its efficacy.

Adult↗
PubMed1984

Metastatic small cell carcinoma of the lung presenting as pituitary apoplexy and Cushing's syndrome.

We describe a woman with metastatic small cell carcinoma of the lung who presented with pituitary apoplexy and hyperprolactinemia. Within seventeen months she developed florid Cushing's syndrome with anasarca, hyperpigmentation, hypertension with marked hypercortisolemia (not suppressible with 8 mg dexamethasone), elevated serum ACTH, hypokalemic metabolic alkalosis, and multiple hepatic metastases. This picture suggested the presence of ectopic ACTH syndrome. She died 26 months after the episode of pituitary apoplexy. Primary small cell carcinoma of the lung was diagnosed post-mortem. Metastases were present in the left lung, regional lymph nodes, heart, liver, bone marrow, sphenoid bone, anterior pituitary and pituitary capsule. Posterior pituitary was normal. There was no evidence of pituitary hyperplasia, of adenoma or of primary pituitary carcinoma. The results suggest the presence of a primary ACTH-producing small cell carcinoma of the lung that metastasized to the parasellar sphenoid bone and then extended to the anterior pituitary and dura to mimic a primary intrasellar cause of pituitary apoplexy and Cushing's syndrome. The case demonstrates how difficult it may be to diagnose the etiology of Cushing's syndrome and it emphasizes a unique variation in the presentation of small cell carcinoma of the lung.

Adrenocorticotropic Hormone↗
PubMed1984

Forskolin increases osmotic water permeability of rabbit cortical collecting tubule.

Forskolin is a unique diterpene that may directly activate the catalytic subunit of adenylate cyclase. We therefore examined the effect of 50 microM forskolin on osmotic water permeability in rabbit cortical collecting tubules perfused in vitro. Forskolin increased net volume flux (Jv, from 0.30 to 1.22 nl/mm/min, P less than 0.02) in all tubules. The hydro-osmotic effect of forskolin was similar with respect to magnitude and time course to that produced by a maximal dose (250 microU/ml) of arginine vasopressin. An additive effect on Jv and Lp was not observed when maximal concentrations of forskolin and arginine vasopressin were given simultaneously. The compound d(CH2)5Tyr(Et) VAVP, which noncompetitively inhibits the vasopressin receptor, significantly reduced collecting tubular hydro-osmotic response to arginine vasopressin. In contrast, the hydro-osmotic response to forskolin was maintained in the presence of d(CH2)5 Tyr(Et)VAVP. However, the hydro-osmotic response to forskolin could be inhibited by 1.0 microM guanine 5'-(beta,gamma-imido) triphosphate (GppNHp) and by the calmodulin inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7). These results demonstrate that forskolin exerts an hydro-osmotic effect in the mammalian nephron which occurs independent of the vasopressin receptor. Guanine nucleotide regulatory proteins may modulate the osmotic water permeability effect of forskolin. Finally, calmodulin is required for full expression of the effect of forskolin to increase osmotic water flux.

Adenylyl Cyclases↗
PubMed1984

Tumorous osteomyelitis. Report of two cases.

Two cases of chronic osteomyelitis with unusual Ewing's like X-ray changes are reported. Inspite of extensive investigations no causative organisms were found. The infection was resistant to different kinds of therapy. The authors suppose that the strange X-ray appearances may be due to an unusual localised immune response of the bone to an unknown, possibly viral agent.

Adolescent↗
PubMed1984

Seizures due to maprotiline overdose.

Maprotiline, a new tetracyclic antidepressant, has a pattern of toxicity that is different from that of tricyclics. Maprotiline overdosage appears more likely to cause seizures but less likely to cause the peripheral autonomic and cardiac manifestations seen with tricyclics. Two cases of maprotiline overdose resulting in seizures without significant anticholinergic or cardiotoxic effects are presented. Both patients were treated acutely with gastric emptying and were observed to have no further seizures during subsequent drug-free hospital and outpatient follow up. Physostigmine salicylate has been used as an antidote for the anticholinergic syndrome of tricyclic overdose, but probably offers less in maprotiline overdose. Careful observation for seizures appears to be warranted.

Adult↗
PubMed1984

Electrophysiologic deficits in peripheral nerve as a discriminator of early hexacarbon neurotoxicity.

To determine the extent of neurotoxicity of parenterally administered hexacarbons, male Sprague-Dawley rats were given either n-hexane or 2,5-hexanedione for 35 consecutive days. Electrophysiologic measurements showed a lengthening of the sciatic and sural nerve action potentials (slower conduction velocities) and increased refractory periods. These effects correlated with a shift in the nerve membrane sensitivity to potassium-induced depolarization. A similar effect can be induced by ouabain, an Na+, K+-ATPase inhibitor. These effects were seen with both n-hexane and 2,5-hexane-dione. Although the treated animals gained weight more slowly than controls, they showed no loss of motor function when tested behaviorally, and there were no signs of histopathology in the peripheral nerves. These results show that hexacarbons produce a neurotoxicity that can be demonstrated by changes in nerve excitability, prior to overt behavioral neurotoxicity. Furthermore, these electrophysiologic changes may be related to a hexacarbon-induced disruption of nerve-membrane ATPase activity.

Animals↗
PubMed1984

Congenital aneurysm of the left atrium: diagnosis and management.

A case of congenital aneurysm of the left atrial appendage is presented and previously reported cases are reviewed. The diagnosis can be strongly suspected with the combination of an unusually prominent left heart border in the chest X-ray and two-dimensional echocardiographic findings of a large echo-free space close to the left atrium. The site of communication must be defined accurately and cardiac catheterisation and angiocardiography should be performed. Once the diagnosis is confirmed, surgery is indicated even in the asymptomatic patient because of the risk of systemic embolism.

Child↗
PubMed1984

Antidiuresis and vasopressin release with hypoxemia and hypercapnia in conscious dogs.

To determine the effects of acute blood gas derangements on renal water and solute excretion and vasopressin secretion, six unanesthetized mongrel dogs were studied during 1) combined acute hypoxemia and hypercapnic acidosis [arterial O2 partial pressure (PaO2) 36 +/- 1 Torr, arterial CO2 partial pressure (PaCO2) 54 +/- 2 Torr, pH 7.18 +/- 0.01], 2) acute hypoxemia (PaO2 33 +/- 2 Torr, PaCO2 33 +/- 1 Torr, pH 7.34 +/- 0.01), and 3) acute hypercapnic acidosis (PaO2 83 +/- 3 Torr, PaCO2 53 +/- 1 Torr, pH 7.19 +/- 0.02). Combined acute hypoxemia and hypercapnic acidosis increased (P less than 0.05) mean arterial pressure, but renal hemodynamic function deteriorated with decreased (P less than 0.05) glomerular filtration rate and increased (P less than 0.05) renal vascular resistance. Moreover free water clearance became more negative (P less than 0.05) and urine osmolality increased (P less than 0.05). During acute hypoxemia or acute hypercapnic acidosis alone, mean arterial pressure and renal hemodynamic function were unchanged but free water clearance became more negative (P less than 0.05). During acute hypoxemia, urine osmolality increased (P less than 0.05) comparably with values observed during combined acute hypoxemia and hypercapnic acidosis. Plasma vasopressin concentrations increased profoundly (P less than 0.05) during combined hypoxemia and hypercapnic acidosis and during acute hypoxemia alone and were significantly elevated (P less than 0.05) above the increased plasma vasopressin concentrations observed during acute hypercapnic acidosis. We conclude that acute hypoxemia and hypercapnic acidosis result in impairment of renal water excretion, probably mediated through vasopressin secretion.

Animals↗
PubMed1984

Role of arginine vasopressin and angiotensin II in cardiovascular responses to combined acute hypoxemia and hypercapnic acidosis in conscious dogs.

The physiological relationship of increased circulating angiotensin II and vasopressin to circulatory changes during combined hypoxemia and hypercapnic acidosis is unclear. To evaluate the role(s) of angiotensin II and vasopressin, seven unanesthetized female mongrel dogs with controlled sodium intake (80 meq/24 h X 4 d) were studied during 40 min of combined acute hypoxemia and hypercapnic acidosis (PaO2, 36 +/- 1 mmHg; PaCO2, 55 +/- 2 mmHg; pH = 7.16 +/- 0.04) under the following conditions: (a) intact state with infusion of vehicles alone; (b) beta-adrenergic blockade with infusion of d,l-propranolol (1.0 mg/kg bolus, 0.5 mg/kg per h); of the vasopressin pressor antagonist d-(CH2)5Tyr(methyl)arginine-vasopressin (10 micrograms/kg); and (d) simultaneous vasopressin pressor and angiotensin II inhibition with the additional infusion of 1-sarcosine, 8-alanine angiotensin II (2.0 micrograms/kg per min). The rise in mean arterial pressure during the combined blood-gas derangement with vehicles appeared to be related to increased cardiac output, since total peripheral resistance fell. Beta-adrenergic blockade abolished the fall in total peripheral resistance and diminished the rise in cardiac output during combined hypoxemia and hypercapnic acidosis, but the systemic pressor response was unchanged. In addition, the rise in mean arterial pressure during the combined blood-gas derangement was unaltered with vasopressin pressor antagonism alone. In contrast, the simultaneous administration of the vasopressin pressor and angiotensin II inhibitors during combined hypoxemia and hypercapnic acidosis resulted in the abrogation of the overall systemic pressor response despite increased cardiac output, owing to a more pronounced fall in total peripheral resistance. Circulating catecholamines were increased during the combined blood-gas derangement with vasopressin pressor and angiotensin II blockade, suggesting that the abolition of the systemic pressor response in the last 30 min of combined hypoxemia and hypercapnic acidosis was not related to diminished activity of the sympathetic nervous system. These studies show that vasopressin and angiotensin II are major contributors to the systemic pressor response during combined acute hypoxemia and hypercapnic acidosis.

Angiotensin II↗