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Biomedical subjects

A B Chapman

Publications and source records attributed to A B Chapman.

At least 19 recordsLinked to original sources
PubMed1992

Intracranial aneurysms in autosomal dominant polycystic kidney disease.

BACKGROUND AND METHODS: Intracranial aneurysms are a feature of autosomal dominant polycystic kidney disease, but their prevalence is uncertain. We studied 92 subjects with autosomal dominant polycystic kidney disease who had no symptoms or signs of any neurologic disorder. To determine the prevalence of intracranial aneurysms, we performed high-resolution computed tomography (CT) in 60 subjects, four-vessel cerebral angiography in 21, and both procedures in 11. RESULTS: Four of the 88 subjects in whom the radiologic studies were successfully completed had intracranial aneurysms (4 percent; 95 percent confidence interval, 0.1 to 9 percent), as compared with the prevalence of 1 percent reported for an angiographic study of the general population. Three of the four subjects had multiple aneurysms. Seven subjects for whom the results of CT studies were suspicious underwent cerebral angiography: two had aneurysms, and five had normal vascular structures that accounted for the suspicious results of tomography. Four subjects who had normal CT imaging studies also had normal angiographic examinations. Eight of the 32 subjects who underwent angiography (25 percent) had transient complications, as compared with 22 of 220 control subjects (10 percent) who did not have polycystic kidney disease (P less than 0.05). We could not identify any risk factor in these subjects that was related to the occurrence of aneurysm. CONCLUSIONS: Asymptomatic intracranial aneurysms appear to be more frequent in people with polycystic kidney disease than in the general population, although our 95 percent confidence interval includes the possibility of no difference. Because cerebral angiography is associated with increased morbidity in people with polycystic kidney disease, we recommend high-resolution CT as a screening test.

Adolescent↗
PubMed1991

Reversible renal failure associated with angiotensin-converting enzyme inhibitors in polycystic kidney disease.

The renin-angiotensin-aldosterone system appears to play an important initiating role in the pathogenesis of hypertension in patients with autosomal-dominant polycystic kidney disease (ADPKD). Therefore, angiotensin-converting enzyme (ACE) inhibitors would appear to be appropriate therapy for hypertension in such patients. However, because ADPKD is a bilateral disorder, ACE-inhibitor therapy may worsen renal function, as occurs in patients with bilateral renal artery stenosis. We describe eight episodes of reversible acute renal deterioration in five patients with ADPKD, massive renal involvement, and chronic renal insufficiency. In all cases, ACE-inhibitor therapy either predisposed the patient to or precipitated the acute event. Two of the patients who had acute renal failure while receiving ACE-inhibitor therapy experienced a recurrence when rechallenged with such therapy. Furthermore, patients receiving combined therapy with an ACE inhibitor and a diuretic and patients who experience a cyst hemorrhage while receiving ACE inhibitor therapy are also at risk for reversible renal dysfunction. Caution is therefore recommended in using ACE inhibitors to treat hypertension in patients with ADPKD who are at high risk because of compromised renal function and massive cystic involvement.

Acute Kidney Injury↗
PubMed1991

Pathogenesis of hypertension in autosomal dominant polycystic kidney disease.

Autosomal dominant polycystic kidney disease is a common (approximately 1 in 400 individuals in the United States) inherited disorder, in which hypertension is the most often associated disorder. Although the development of hypertension originates with expansion of renal cysts, it most likely has its pathogenesis in the renal vasculature. Evidence is now accumulating that the renin-angiotensin-aldosterone system is important in the development and maintenance of hypertension in this disorder. End-organ damage including left ventricular hypertrophy and progressive renal insufficiency appear to be related to the presence of hypertension in ADPKD. A focus on early detection and adequate control of hypertension in ADPKD, therefore, may be associated with improved cardiovascular and renal outcomes as well as increased patient survival in ADPKD.

Humans↗
PubMed1990

The renin-angiotensin-aldosterone system and autosomal dominant polycystic kidney disease.

BACKGROUND: A high incidence of hypertension (50 to 75 percent) occurs early in the course of autosomal dominant polycystic kidney disease. Cyst enlargement, causing bilateral renal ischemia and subsequent release of renin, is proposed as the cause of this form of hypertension. METHODS: To investigate this hypothesis, we measured plasma renin activity and aldosterone concentrations during short-term and long-term converting-enzyme inhibition in 14 patients with hypertension due to polycystic kidney disease, 9 patients with essential hypertension, 11 normotensive patients with polycystic kidney disease, and 13 normal subjects. The groups were comparable with respect to age, sex, body-surface area, degree of hypertension, sodium excretion, and renal function. RESULTS: During the short-term study, the mean (+/- SE) plasma renin activity was significantly higher in the hypertensive patients with polycystic kidney disease than in the patients with essential hypertension, in the supine (0.36 +/- 0.06 vs. 0.22 +/- 0.06 ng per liter.second, P = 0.05) and upright positions (1.03 +/- 0.14 vs. 0.61 +/- 0.08 ng per liter.second, P less than 0.03) and after converting-enzyme inhibition (1.97 +/- 0.28 vs. 0.67 +/- 0.17 ng per liter.second, P less than 0.0006). The mean arterial pressures measured in the supine and upright positions and the plasma aldosterone concentrations measured in the upright position were significantly higher in the normotensive patients with polycystic kidney disease than in the normal subjects. After six weeks of converting-enzyme inhibition, renal plasma flow increased (P less than 0.005), and both renal vascular resistance (P less than 0.007) and the filtration fraction (P less than 0.02) decreased significantly in the hypertensive patients with polycystic kidney disease but not in the patients with essential hypertension. CONCLUSIONS: The renin-angiotensin-aldosterone system is stimulated significantly more in hypertensive patients with polycystic kidney disease than in comparable patients with essential hypertension. The increased renin release, perhaps due to renal ischemia caused by cyst expansion, probably contributes to the early development of hypertension in polycystic kidney disease.

Adult↗
PubMed1990

Percutaneous cyst puncture in the treatment of cyst infection in autosomal dominant polycystic kidney disease.

Cyst infection in autosomal dominant polycystic kidney disease (ADPKD) poses a difficult diagnostic and therapeutic problem. We describe a serious indolent cyst infection due to Staphylococcus aureus, which was successfully diagnosed and treated with repeated percutaneous cyst drainage and intravenous (IV) antibiotic therapy. Cyst aspiration also permitted monitoring of cyst antibiotic levels and evidence of active infection.

Adult↗
PubMed1990

Renal structure and hypertension in autosomal dominant polycystic kidney disease.

Hypertension has been reported to occur in 50 to 75 percent of subjects with autosomal dominant polycystic kidney disease (ADPKD) prior to the onset of marked renal insufficiency but concurrent with cystic deformation of the renal parenchyma. The present study was undertaken to examine whether the renal structural abnormalities are greater in hypertensive (HBP) versus normotensive (NBP) male and female patients with ADPKD who were matched within gender groups for age, body surface area, serum creatinine concentration (males HBP 1.2 +/- 0.02 vs. NBP 1.1 +/- 0.03 mg/dl. NS: females HBP 0.9 +/- 0.03 vs. NBP 0.9 +/- 0.02 mg/dl, NS) and creatinine clearance (males HBP 100 +/- 3 vs. NBP 108 +/- 3 ml/min/1.73 m2, NS: females HBP 97 +/- 3 vs. NBP 96 +/- 2 ml/min/1.73 m2, NS). Renal volume was significantly greater in the HBP compared to the NBP group (males HBP 624 +/- 47 vs. NBP 390 +/- 43 cm3, P less than 0.0005; females HBP 446 +/- 32 vs. NBP 338 +/- 24 cm3, P less than 0.002). Since increased renal volume is due to increased cysts, the results indicate that the early high incidence of hypertension in ADPKD correlates with the renal structural abnormalities in this disorder.

Adult↗
PubMed1990

Serum amylase in patients with renal insufficiency and renal failure.

Results vary with regard to the upper limits of serum amylase seen in patients with renal failure, and very little has been reported with patients with renal insufficiency not yet requiring dialysis. To determine the level of serum amylase elevation in renal insufficiency and renal failure, we determined serum amylase values in 128 subjects with creatinine clearances less than 90 ml/min. Serum amylase remained in the normal range when creatinine clearance was greater than 50 ml/min, and did not become elevated until creatinine clearance was less than 50 ml/min. The highest serum amylase recorded in the absence of acute pancreatitis was 503 IU/L (normal, less than 128 IU/L). Serum lipase and trypsin values paralleled those for serum amylase; values remained normal when creatinine clearance was greater than 50 ml/min, and were normal or elevated when creatinine clearance was less than 50 ml/min. These results indicate that elevations of serum amylase (i.e., amylase greater than 128 but less than 500 IU/L) in asymptomatic patients with impaired renal function are not evident until creatinine clearances fall below 50 ml/min, and probably do not represent acute pancreatitis.

Acute Disease↗
PubMed1987

Requirements for triggering of adipocyte differentiation by glucocorticoids and indomethacin.

The stable adipogenic cell line TA1, spontaneously differentiates into mature adipocytes after several days at confluence. Glucocorticoids (e.g. dexamethasone) accelerate the onset of differentiation by precociously activating the transcription of genes that are expressed in the mature adipocyte but not in the preadipocyte. Thus the hormone may induce a critical regulatory factor required for activating the entire set of differentiation-dependent genes. We have found that the nonsteroidal antiinflammatory drug indomethacin also stimulates differentiation of TA1 cells but even more rapidly and completely than does dexamethasone. Contrary to previous suggestions we find that this activity of indomethacin's cannot be ascribed to inhibition of cyclo-oxygenase, the critical enzyme in prostaglandin biosynthesis. Finally, indomethacin's ability to stimulate TA1 cell differentiation synchronously and rapidly has allowed us to document that cell confluence is required for efficient differentiation and that the drug needs only to trigger rather than maintain the differentiation process.

Adipose Tissue↗
PubMed1986

Glucocorticoid control of developmentally regulated adipose genes.

We have analyzed the hormonal basis for the acceleration of differentiation by dexamethasone in the stable adipogenic cell line TA1. These cells, which were derived from 5-azacytidine-treated 10T1/2 mouse embryo fibroblasts, undergo differentiation in culture after reaching confluence. Using cDNA clones corresponding to mRNAs that are induced during adipogenesis, we find that dexamethasone elicits the precocious accumulation of differentiation-specific gene products. This effect appears to be mediated by the glucocorticoid receptor, yet unlike standard steroid inductions, most of the RNAs reach the same maximal levels in the absence of dexamethasone. Glucocorticoids thus may increase the expression of a regulatory factor required for activating the entire set of differentiation-dependent genes. We also describe a gene whose transcription is not only activated during adipogenesis, but is also specifically inducible by dexamethasone in the mature adipocyte. Moreover, the glucocorticoid responsiveness of this gene in differentiated cells appears to be dependent on its prior developmental activation.

Adipose Tissue↗
PubMed1986

Hormonal control of adipogenesis.

The concept that hormonal substances can alter the expression of entire developmental programs is in itself not particularly new. The ability to define conditions under which a specific hormone can precociously activate the differentiation of a well-defined population of cells and under which another hormone can both block and reverse such a developmental progression, however, provides a major step forward toward unraveling the biochemical events that define the transition from a committed precursor to a fully differentiated cell. Further analysis of the molecular events initiated by glucocorticoids and TNF should provide insights into the control of adipogenesis and may generate a foundation for understanding the mechanisms by which other cells enter a particular differentiative lineage. In a more applied sense, such knowledge may also provide a rational approach to controlling metabolic disease syndromes related to adipogenesis gone awry such as obesity-associated diabetes and cachexia.

Adipose Tissue↗