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Biomedical subjects

J D Albano

Publications and source records attributed to J D Albano.

At least 19 recordsLinked to original sources
PubMed1998

Modifying effects of amlodipine on cyclosporin A-induced changes in renal function in patients with psoriasis.

OBJECTIVE: To assess the benefit of amlodipine, a calcium channel blocker, on renal function and vasoactive hormones in individuals with normal kidneys and blood pressure and who were being treated with cyclosporin A for refractory psoriasis. DESIGN: An open-label, two-stage, longitudinal study was employed. METHODS: Patients were divided into two groups: Group I received cyclosporin A, 5 mg/kg per day for 6 months titrated down to 2.5-3.5 mg/kg per day for 6 months, then concomitant amlodipine 5 mg/day for 6 months; and Group II received concomitant cyclosporin A, 5 mg/kg per day, and amlodipine, 5 mg/day, for 6 months. Blood pressure, serum creatinine, glomerular filtration rate, urinary magnesium, plasma renin activity and urinary kallikrein excretion were measured before and after treatment. RESULTS: Eighteen patients were enrolled, and 12 completed the study. In Group I (n = 7), 12 months of cyclosporin A therapy significantly increased systolic blood pressure and significantly decreased glomerular filtration rate, plasma renin activity and active urinary kallikrein. Amlodipine reversed these changes. In Group II (n = 5), 6 months of concomitant cyclosporin A and amlodipine significantly reduced active urinary kallikrein levels. No significant changes occurred in the other measured parameters in either group. CONCLUSIONS: Cyclosporin A produces a sustained and significant fall in glomerular filtration rate and urinary kallikrein excretion, even in patients with normal kidneys and blood pressure. Amlodipine is potentially capable of reversing these nephrotoxic effects.

Adult↗
PubMed1996

Early prediction of pre-eclampsia by measurement of kallikrein and creatinine on a random urine sample.

OBJECTIVE: To assess the measurement of inactive urinary kallikrein (IUK) to creatinine (Cr) ratio (IUK:Cr) on an untimed urine sample, collected between 16 and 20 weeks of pregnancy, as a predictive test for the development of both proteinuric and nonproteinuric pre-eclampsia. DESIGN: A prospective longitudinal study. SETTING: A clinic for antenatal care and a university research department. PARTICIPANTS: Three hundred and seven normotensive women randomly selected (124 nulliparous and 183 parous) attending the antenatal clinic for their booking visit. MAIN OUTCOME MEASURES: 1. Nonproteinuric pre-eclampsia: a rise in diastolic blood pressure of 25 mmHg or more and a crossing of the threshold of 90 mmHg; 2. Proteinuric pre-eclampsia: same as 1. plus the development of significant proteinuria ( > 1 + on urine dipstick). RESULTS: Thirty-seven women developed pre-eclampsia, 12 of whom had proteinuria. Median IUK:Cr ratio in this group was 78.27, compared with 358.19 in the remainder. Analysis of receiver-operator characteristics gave an area under the curve of 0.803. An IUK:Cr ratio of 170 or less in this study predicted nonproteinuric or proteinuric pre-eclampsia with a sensitivity of 70% and a specificity of 86%. Ten of the twelve women who had proteinuria had an IUK:Cr below 170. Median IUK:Cr for those with proteinuric pre-eclampsia was 72.91. CONCLUSIONS: Measurement of IUK:Cr on a urine sample, collected between 16 and 20 weeks of gestation, represents a simple and practical test for the risk of subsequent pre-eclampsia, with a sensitivity and specificity comparable to those reported by other investigators using the widely recognised, but less practical, angiotensin II sensitivity test.

Adult↗
PubMed1994

Gender differences in urinary kallikrein excretion in man: variation throughout the menstrual cycle.

1. Urinary kallikrein excretion was measured in healthy male subjects and in healthy pre- and post-menopausal females. 2. Urinary kallikrein excretion was shown to be constant throughout a 24 h period. Individual male subjects showed little fluctuation in urinary kallikrein excretion; within-subject variance accounted for 1.65% of the total. 3. Female subjects with ovulatory menstrual periods excreted significantly more kallikrein than post-menopausal females and males. 4. Pre-menopausal females showed a much greater within-subject variation in urinary kallikrein excretion and this could be related to the stage of the menstrual cycle, with significantly greater urinary kallikrein excretion in the luteal phase than in the follicular phase. 5. Plasma renin activity and plasma aldosterone concentration also showed a menstrual variation, with concentrations in the luteal phase being significantly higher than those in the follicular phase. 6. The rise in urinary kallikrein excretion in the luteal phase could be abolished by oral administration of the aldosterone antagonist spironolactone. 7. Urinary kallikrein excretion in post-menopausal females was similar to the range found in males, and showed no cyclic changes over a 4 week period. 8. Gender and menstrual status should be taken into account in studies of the physiological role of tissue kallikreins.

Adult↗
PubMed1992

Biological assay for tissue kallikrein: comparison with the synthetic substrate S2266.

A highly sensitive biological assay for tissue kallikrein is described, using human kininogen as substrate; and quantitation, by radioimmunoassay, of generated kinins. Using purified human urinary kallikrein as a reference standard we have correlated the kininogenase activity of kallikrein with amidase activity as measured by cleavage of the synthetic substrate S2266.

Animals↗
PubMed1990

Active and inactive urinary kallikrein in man: effects of diuresis and antidiuresis.

1. The urinary excretion of active and inactive kallikrein was studied in volunteers during diuresis induced by water loading or oral frusemide and during antidiuresis induced by desamino-D-arginine-vasopressin. 2. During acute oral water loading, excretion of active kallikrein was unchanged, despite high urine flow rates and low urine osmolalities being achieved. Excretion of inactive kallikrein correlated with the urine flow rate. 3. After desamino-D-arginine-vasopressin in eight water-loaded and six normally hydrated subjects, excretion of inactive kallikrein also correlated with the urine flow rate. There were no significant changes in the excretion of active kallikrein. 4. After frusemide there was a small transient increase in excretion of active kallikrein 1-2 h after dosing which coincided with the maximum diuresis and natriuresis. Excretion of inactive kallikrein again correlated with urine flow rate but the regression relationship between the two variables was different for water-load-induced and frusemide-induced diuresis. 5. These studies do not support a role for urinary kallikrein in the modulation of the antidiuretic action of vasopressin, but suggest that it may contribute to the natriuretic action of frusemide.

Adult↗
PubMed1990

Bartter's syndrome and diabetes mellitus.

We here report a case of Bartter's syndrome occurring in association with diabetes mellitus. The patient, an insulin-dependent diabetic, presented with hypokalaemia, inappropriate kaliuresis and metabolic alkalosis. He had high plasma renin activity, relatively low plasma aldosterone, and resistance to infused angiotensin II. A high potassium diet raised total body potassium and serum potassium, did not affect plasma renin activity, but raised plasma aldosterone significantly and did not alter the resistance to angiotensin II. Indomethacin administered acutely reduced urinary potassium and kallikrein excretion and, on chronic administration, lowered plasma renin activity, urinary chloride excretion, and raised serum potassium. Salt restriction resulted in a prompt and significant reduction in urinary sodium and chloride excretion. Urinary kallikrein excretion was very high throughout, increased with sodium restriction, and decreased with sodium loading. Oral potassium supplementation partially corrected the hypokalaemia, but did not affect blood sugar control. In this patient the primary defect appears to have been primary urinary potassium wasting, rather than sodium or chloride wasting. The striking effects of indomethacin suggest that prostaglandins may play a fundamental role in the genesis of the syndrome.

Adult↗
PubMed1989

Pharmacokinetics of cyclosporin in man following a single oral dose: relationship to body fat content.

We have investigated the pharmacokinetics of the immunosuppressive drug cyclosporin in 11 patients receiving regular dialysis therapy. After a single oral dose of cyclosporin, whole blood concentrations were measured at regular intervals for 24 h. Body fat content was estimated in each subject from the measurement of skin-fold thickness and mid-arm circumference. In ten of the 11 patients there was a relatively uniform response in the increase of cyclosporin blood concentration to a peak within the first 6 h. Calculated area under the blood concentration curve did not correlate with total bodyweight, but correlated strongly with body fat content as well as fat-free mass. This study suggests that more predictable blood concentrations of cyclosporin might be achieved if the initial dose were calculated on the basis of fat-free mass rather than total bodyweight.

Adipose Tissue↗
PubMed1988

A simplified method for monitoring blood concentration of cyclosporin by a finger-stab technique.

We have developed a simple method of sample collection which allows the measurement of cyclosporin (CsA) to be made from blood obtained from a finger stab and collected onto filter paper. CsA concentrations estimated from blood spots and venous samples obtained at the same time showed good correlation. This method has various practical applications: peak and trough blood CsA concentrations (as well as profiles) may be routinely measured from samples collected by patients at home; it may be of particular value in children and other patients with poor venous access.

Cyclosporins↗
PubMed1986

Assessment of new radioimmunoassay kit for determining urinary albumin at low concentrations: comparison with radial immunodiffusion.

The assay characteristics of a new radioimmunoassay kit for determining urinary albumin at low concentrations were studied. The sensitivity for urinary albumin was 2 mg/l, the analytical range 2 to 40 mg/l, and interassay coefficient of variation less than 12%. In a method comparison study entailing diabetic urine samples covering an albumin concentration of 2 to 150 mg/l the kit compared adequately with radial immunodiffusion (mean difference between methods = 2 mg/l; residual standard deviation = 4.6 mg/l), absolute variation between methods increasing with the concentration. The kit required much less skill than radial immunodiffusion but its capital and running cost were higher.

Albuminuria↗
PubMed1984

Cyclic AMP responses to parathyroid hormone and glucagon during lithium treatment.

Inhibition of adenylate cyclase has been proposed as a mechanism for hypothyroidism and nephrogenic diabetes insipidus occurring during lithium treatment, but these disorders are rarely found in the same patients. We have measured plasma levels of adenosine 3':5'-cyclic monophosphate (cyclic AMP) after an intravenous injection of glucagon in eight patients receiving long term lithium treatment and in six control subjects. Urinary cyclic AMP levels after an intravenous injection of bovine parathyroid hormone (PTH) were also measured in the patients. The plasma cyclic AMP response to glucagon in the patient group was significantly lower than that of the controls. No correlation was demonstrated between the plasma cyclic AMP response after glucagon and the urinary cyclic AMP response after PTH. We have previously shown that impairment of the response to PTH correlates with reduced urine concentrating ability during lithium treatment. In contrast, there was no correlation between the responses to PTH and glucagon in individual patients. These results are consistent with the hypothesis that inhibition of adenylate cyclase is an important factor in lithium-induced endocrine dysfunction.

Adult↗
PubMed1983

Impairment of cyclic AMP response to bovine parathyroid hormone in patients on chronic lithium therapy with diminished renal urine-concentrating ability.

1. Urinary and plasma levels of adenosine 3':5'-cyclic monophosphate (cyclic AMP) after an intravenous injection of bovine parathyroid hormone (PTH) were measured in 12 patients on long-term lithium treatment and in nine control subjects. The maximum urine osmolality (Umax.) after an intravenous injection of desamino-D-arginine vasopressin (DDAVP) was also measured. 2. In all the control subjects and six of the patients, the Umax. after DDAVP exceeded 700 mosmol/kg. The cyclic AMP responses in these two groups did not differ significantly. 3. In the remaining six patients whose Umax. did not reach 700 mosmol/kg, the cyclic AMP response to PTH was significantly less than that of the controls. 4. A strong correlation was demonstrated in the patients between the urinary cyclic AMP response after PTH and the maximum osmolality after the administration of DDAVP. 5. These observations are consistent with the hypothesis that reduced adenylate cyclase activity contributes to the development of nephrogenic diabetes insipidus in patients on long-term lithium treatment.

Adult↗
PubMed1976

The development of adrenocorticotrophin-sensitive adenylate cyclase activity in the foetal rabbit adrenal: a correlated biochemical and morphological study.

Proliferation of the smooth endoplasmic reticulum, the site of some hydroxylating steroidogenic enzymes in foetal adrenocortical cells, is the first major change in the process of their differentiation into steroidogenic tissue. This was observed in our ultrastructural studies on foetal rabbit adrenals to begin at about day 19 of development. Morphological changes in the mitochondria, the site of production of other steroidogenic enzymes, occurred at about day 24. The elongated or rod-shaped forms of the earlier stages became flattened and rounded by this time, while the cristae were transformed from a flattened lamellar type of the earlier stages to the tubulo-vesicular form of the adult. Other changes observed included an increase in microvilli and in cell size, with a concomitant increase in thickness of the gland. Adenylate cyclase activity in foetal adrenal homogenates was assessed in response to sodium fluoride (NaF) and ACTH. All preparations responded to NaF. While good responses to ACTH were observed at days 24, 27, 28 and in the neonate, there was a lack of any significant response in the day 19 gland. Foetal ACTH was depressed by administration of cortisol, and the effects of this treatment on both the morphological changes and adenylate cyclase activity was reassessed. The response of foetal adrenals to ACTH was depressed by this treatment and differentiation of the mitochondria was arrested. These results suggest a circumscribed period for the development of ACTH-sensitive adenylate cyclase coinciding with the time at which final differentiation of the mitochondria is completed. Furthermore, both the differentiation of the mitochondria and the development of ACTH-sensitive adenylate cyclase in the foetal adrenal may be dependent on foetal ACTH secretion.

Adenylyl Cyclases↗