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Biomedical subjects

R D Gordon

Publications and source records attributed to R D Gordon.

At least 109 records · Page 6Linked to original sources
PubMed1992

Familial hyperaldosteronism type II: five families with a new variety of primary aldosteronism.

1. Thirteen patients from five families had Familial Hyperaldosteronism Type II (FH-II), a new variety of familial primary aldosteronism not suppressible with dexamethasone that often involves adrenocortical adenoma formation. 2. Five patients had solitary aldosterone-producing adenomas, three had bilateral autonomous overproduction of aldosterone, and in five the subtype is yet to be determined. 3. Comparing FH-II patients with 88 patients with primary aldosteronism of other causes revealed no differences in mean age at presentation or at onset of hypertension, sex incidence, lowest recorded serum potassium, plasma aldosterone, plasma renin activity or adenoma size. 4. Analysis of DNA in peripheral blood of patients with FH-II, their affected and unaffected relatives, and in removed tumours is in progress in order to determine the underlying genetic defect(s) in FH-II, perhaps an abnormality in the P-450aldo gene (CYP11B2). 5. It is recommended that hypertensive relatives of patients with primary aldosteronism should have measurements of the aldosterone/renin ratio.

Adult↗
PubMed1992

Prostaglandins and systolic blood pressure, but not angiotensin II, independently affect atrial natriuretic peptide levels in man.

1. Two hours after a single dose of indomethacin (INDO), plasma renin activity (PRA) and atrial natriuretic peptide (ANP) levels decreased, which is consistent with an effect of lowering prostaglandins (PG). 2. After 48 h of INDO, PRA remained low but ANP had increased, which is consistent with the known effect of prostaglandin inhibitors to cause sodium retention, with a resulting volume expansion. 3. Infusions of angiotension II (AII), which raises diastolic blood pressure (BP) 20 mmHg or more, consistently raised ANP levels. The ANP response to AII infusion was reduced 48 h after INDO, which is consistent with an important role for PG in AII-stimulated ANP release. 4. After PG were blocked with INDO, the stimulating effect of AII on ANP at doses that increased diastolic BP less than 20 mmHg was insignificant, whereas before INDO it was significant. 5. In dose-response studies, INDO increased the systolic BP response but decreased the ANP response to AII, which is consistent with a direct effect of PG on ANP that is independent of systolic BP. 6. Prostaglandins and BP are important in the ANP response to AII infusion in normal subjects, but AII itself appears to have little direct effect on ANP.

Adult↗
PubMed1991

Solution structure of mu-conotoxin GIIIA analysed by 2D-NMR and distance geometry calculations.

We have investigated the structure of mu-conotoxin GIIIA by 2D-NMR methods. The assignment of 1H NMR spectra and a quantitative analysis of NOE and J-coupling data are presented. These results were used for the calculation of secondary structure elements of mu-conotoxin GIIIA. Distance geometry calculations were carried out to define the global folding of the peptide.

Amino Acid Sequence↗
PubMed1991

The liver transplant waiting list--a single-center analysis.

At this transplant center 1340 patients were entered on the liver transplant waiting list during the first 25 months (October 1987 to November 1989) after the initiation of the UNOS allocation system for liver grafts. Of these 972 (72.5%) of the patients received a graft, 120 (9.0%) died waiting for a graft, 109 (8.1%) remained on the active list as of the study endpoint of December 15, 1989, 123 (9.2%) were withdrawn from candidacy, and 16 (1.2%) received a transplant at another center. A total of 1201 patients were candidates for a first graft. Of the 812 primary candidates who received a graft, 64.8% received their graft within one month of entry on the waiting list. Of the 109 primary candidates who died before a graft could be found, 79.0% died within a month of entry onto the waiting list. At time of transplantation, 135 (16.6%) primary recipients of a graft were UNOS class 1, 326 (40.1%) were UNOS class 2, 190 (23.4%) were UNOS class 3, and 161 (19.8%) were UNOS class 4. Actuarial survival rates (percentage) at 6 months for recipients in UNOS class 1, class 2, class 3, and class 4 were 88.7 +/- 2.9, 82.6 +/- 2.1, 78.4 +/- 3.2, and 68.4 +/- 3.9, respectively (P less than 0.001). At the time of death of recipients who failed to get a graft, 6 (5.5%) were UNOS class 1, 14 (12.8%) were UNOS class 2, 23 (21.1%) were UNOS class 3, and 66 (60.6%) were UNOS class 4. These results indicate that a high proportion of liver transplant candidates are in urgent need of a graft and that the UNOS system succeeds in giving these patients high priority. However patient mortality on the waiting list and after transplantation would lessen significantly if more patients with end-stage liver disease were referred to the transplant center in a timely manner before their condition reaches the point where the probability of survival is diminished.

ABO Blood-Group System↗
PubMed1991

Cardiovascular effects of a chlorpheniramine/paracetamol combination in hypertensive patients who were sensitive to the pressor effect of pseudoephedrine.

Twelve hypertensive patients who were classified as pseudoephedrine-sensitive in a preliminary trial were selected for further investigation with single doses of pseudoephedrine 60 mg, a combination of chlorpheniramine 4 mg with paracetamol 650 mg and placebo. A double-blind, randomised, crossover study design was followed. Treatment with pseudoephedrine produced significant effects on all the four variables measured (systolic, diastolic and mean arterial blood pressure, and heart rate). Effects of the chlorpheniramine/paracetamol combination were found to be not significantly different from placebo. It was concluded that the combination may be useful as a medication for 'colds' in hypertensive patients, since it does not induce cardiovascular effects such as those observed with pseudoephedrine.

Acetaminophen↗
PubMed1991

Histological and biochemical distinctiveness of atypical aldosterone-producing adenomas responsive to upright posture and angiotensin.

Fifteen patients with primary aldosteronism were classified as angiotensin II-unresponsive aldosterone-producing adenoma (AII-U APA, n = 9), or angiotensin II-responsive aldosterone-producing adenoma (AII-R APA, n = 6), based on the responsiveness of aldosterone to upright posture and to angiotensin II infusion. Lack of aldosterone response to angiotensin II infusion immediately postoperatively in the AII-R APA subtype was consistent with previous responsiveness residing solely within the adenoma. Cortisol levels in five of the six patients with AII-R APA failed to suppress normally with dexamethasone consistent with some autonomous production of cortisol by the adenoma. In contrast, cortisol levels suppressed normally during dexamethasone administration in all patients with AII-U APA. This biochemical distinction can be added to the previously described overproduction of 18-oxo cortisol in AII-U APA but not in AII-R APA. Histological examination of adenoma sections revealed predominantly (greater than or equal to 50%) zona fasciculata type cells in AII-U APA. In contrast, AII-R APA contained less than 20% zona fasciculata type. Thus, biochemical differences between AII-U APA and AII-R APA subtypes of primary aldosteronism may be due to underlying differences in cellular composition of the aldosterone-producing adenomas.

Adenoma↗
PubMed1991

Sodium and volume dysregulation after apparently normal pregnancy is suggested by abnormal levels of atrial natriuretic peptide, renin and aldosterone.

1. Plasma atrial natriuretic peptide (ANP), renin activity, aldosterone, sodium, potassium and serum total protein and albumin during and after 14 normal pregnancies were compared with age-matched controls. 2. None developed toxaemia and all delivered healthy babies. 3. During pregnancy, plasma renin activity and aldosterone were significantly (P less than 0.01) higher and potassium, total protein and albumin significantly lowew (P less than 0.01) than in controls, while ANP was not different from the control level. 4. At 6-13 weeks postpartum, a significant (P less than 0.01) suppression of renin and aldosterone was accompanied by significant (P less than 0.01) elevation of atrial natriuretic peptide when compared with controls. 5. The hormonal changes are consistent with 'effective plasma volume' reduction during pregnancy and persistent volume expansion after pregnancy, perhaps due to a renal glomerular lesion sustained late in pregnancy. In contrast, levels of potassium, total protein and albumin are consistent with haemodilution during pregnancy and its correction postpartum. 6. Measurements available in seven women 40-120 weeks postpartum showed normal renin and aldosterone levels in most, but ANP was still elevated. 7. Pregnancy may have a protracted effect on volume regulation.

Adult↗
PubMed1991

Clonidine suppression test reliably differentiates phaeochromocytoma from essential hypertension.

1. Clonidine resulted in significant suppression of both noradrenaline (NA) and adrenaline (ADR) in essential hypertensives (EHT) without any false positive findings. That is, every patient who failed to suppress had phaeochromocytoma (PH). 2. The clonidine suppression test (CST) produced minimal suppression of NA in NA-secreting PH (NA-PH) and correctly identified two NA-PH with normal basal plasma NA. 3. In ADR-secreting PH (ADR-PH) the CST did not result in significant suppression of ADR levels, whether elevated or normal basally. 4. The CST proved to be an accurate discriminator of PH from other forms of hypertension.

Adolescent↗
PubMed1991

Clinical and pathological diversity of primary aldosteronism, including a new familial variety.

1. Of 93 patients with primary aldosteronism seen during a 20 year period, 52 had an aldosterone-producing adenoma (APA) removed (five more await surgery), 14 had bilateral adrenal hyperplasia (BAH), three had glucocorticoid-suppressible hyperaldosteronism (GSH), one had adrenal carcinoma and 18 are yet to be categorized. 2. Seventy-three presented with hypertension and hypokalaemia. Others had markedly suppressed renal venous plasma renin activity (PRA) or elevated plasma aldosterone (PA)/PRA ratio, in new or resistant hypertensives. 3. The PA/PRA ratio was the most reliable screening test. 4. Diagnosis depended on the failure of suppression of aldosterone by salt loading and fludrocortisone. 5. Differentiation of BAH from APA depended on adrenal venous sampling comparing adrenal and peripheral venous PA/cortisol ratios. 6. A new familial variety of primary aldosteronism is described, with two affected members in each of three families. 7. Primary aldosteronism should be looked for in resistant and low-renin hypertension as well as in hypertension with hypokalaemia, and other family members should have PA/PRA measured if they are hypertensive.

Adenoma↗
PubMed1991

Potassium, glucose, insulin interrelationships during adrenaline infusion in normotensive and hypertensive humans.

1. Significant increases in arterial noradrenaline (NA) of similar magnitude were seen in normotensive (NT) and hypertensive humans (HT) during adrenaline (ADR) infusion. 2. Significant falls in plasma potassium (K+) were observed in both NT and HT during ADR infusion, even at rates equivalent to minor stress. Levels achieved were significantly lower in HT than in NT. 3. Plasma glucose increased significantly in HT at all ADR infusion rates but only at higher rates of infusion in NT. 4. Basal insulin levels were significantly higher in NT than in HT. After cessation of infusion, insulin increased three-fold in HT and two-fold in NT. 5. Infusion of ADR to produce levels seen during mild to moderate stress resulted in significant increases in plasma NA, falls in plasma K+ and increases in plasma glucose. The expected large insulin response to rising glucose was not seen until after ADR was ceased, confirming the inhibitory effect of ADR on glucose stimulated insulin release.

Adult↗
PubMed1991

Does urinary atrial natriuretic peptide reflect plasma levels in humans?

1. Saline infusion produced concurrent mean increases over basal in plasma and urinary atrial natriuretic peptide (ANP) of approximately 100%. 2. Subpressor calcium infusion also produced concurrent increases in plasma and urinary ANP of 38 and 60% respectively. 3. Urinary ANP appeared to be as responsive to the dynamic stimulation of saline and calcium infusion as plasma levels. 4. Urinary ANP may be useful when an integrated estimation of ANP secretion and metabolism is required. Further studies are required to assess clinical utility in a variety of settings, for example during endopeptidase 3.4.24.11 inhibition.

Adult↗
PubMed1991

The syndrome of hypertension and hyperkalaemia with normal glomerular filtration rate: is there a deficiency in vasodilator prostaglandins?

1. In Gordon's syndrome (GS; a syndrome of hypertension and hyperkalaemia with normal glomerular filtration rate), excessive proximal sodium reabsorption leads to suppression of renin and aldosterone, hyperkalaemia and hyperchloraemic acidosis. 2. Low urinary levels of vasodilator prostaglandins (PG) have been reported in GS, suggesting renal hypoprostaglandinism as a pathophysiological mechanism. 3. In four cases of GS, levels of vasodilator prostaglandins PGE2 and 6-keto-PGF1 alpha were low. 4. In one case of GS, low PGE2 levels were normalized by dietary salt restriction or diuretic therapy.

Adult↗
PubMed1991

Liver transplantation at the University of Pittsburgh, 1984 to 1990.

Patient and primary graft survival for 2,090 patients who received primary liver transplants at the University of Pittsburgh from 1984 through 1990 are presented. Observed (actual) 3- and 12-month patient and primary graft survival rates were compared for 3 periods: 1) January 1984 to September 1987 (cyclosporine, OKT3, and Euro-Collins preservation period); 2) October 1987 to December 1988 (University of Wisconsin solution preservation period); and 3) January 1989 to December 1990 (FK506 period). Data for results according to age group, medical urgency, and primary diagnosis are provided. In addition, estimated survivor and cumulative hazard functions (life-table method) for patient and primary graft survival out to 60 months after transplantation are presented. Overall results have improved significantly in recent experience. Most notable are the improved results seen in liver transplantation for patients with biliary atresia (especially in infants), primary sclerosing cholangitis, fulminant hepatic failure, and chronic active hepatitis B. For all but a few conditions, most of the mortality after liver transplantation occurred in the first 3 months after surgery. Less than 2% of patients were lost in each 6-month interval beyond the first 6 months after transplantation. Outcome was related to patient condition at the time of surgery. Observed survival rates at 3 and 12 months for patients called in the hospital to receive a transplant were 88.6% and 86.5%, respectively, compared with 81.9% and 73.7% for patients in critical condition. The continuing shortage of organs for transplantation, which often forces patients to wait longer for an organ than they can afford to, continues to impose a significant penalty.

Adolescent↗