Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Han:SPRD (PKD) rat is a new animal model of autosomal dominant polycystic kidney disease (ADPKD) which resembles many clinical and pathoanatomical features of human ADPKD. The aim of the present study was to analyse age-dependent changes in renal haemodynamics and renal renin secretion which could be of pathophysiological importance in the course of the disease. We investigated glomerular filtration rate (GFR), renal blood flow (RBF), renal vascular resistance (RVR), plasma renin activity (PRA), the autoregulatory behaviour of RBF and the pressure-dependent plasma renin activity in conscious PKD rats compared with age-matched controls. Experiments were performed in conscious chronically instrumented PKD rats (age: 3 and 9 months) and their age-matched genetic controls. GFR in 3-(0.52 +/- 0.07 ml/min/100 g; n = 9) and 9-month-old (0.42 +/- 0.03 ml/min/100 g; n = 21) PKD rats were significantly lower (P < 0.05) than 3- (0.92 +/- 0.07 ml/min/100 g; n = 17) and 9-month-old (0.67 +/- 0.05 ml/min/100 g; n = 17) controls. Nine-month-old PKD revealed a significant (P < 0.005) resetting of the breakpoint of RBF autoregulation towards lower pressures (85.5 +/- 4.4 mmHg; n = 10) than either age-matched controls (102.8 +/- 2.5 mmHg; n = 11) or young PKD (107.5 +/- 4.4 mmHg; n = 6). The basal plasma renin activity was significantly (P < 0.05) lower in 3-month-old PKD than in old PKD and age-matched controls. A significant shift of threshold pressure for pressure-dependent renin release to lower pressures was observed in PKD rats. The observed improvement of autoregulatory reserve, at least in the low pressure range, could be of pathophysiological importance in delaying the progression of chronic renal failure in ADPKD. The suppression of the renin angiotensin system in young PKD could explain the fact that we did not observe hypertension in PKD rats, which is a major difference between this animal model and human ADPKD.
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PMID:Autoregulation of renal blood flow and pressure-dependent renin release in autosomal dominant polycystic kidney disease of rats. 904 29

Autosomal dominant polycystic kidney disease (ADPKD) progresses to end-stage renal insufficiency before the age of 73 in approximately 48% of affected individuals. Why the disease, characterized by innumerable cysts arising in proximal and distal tubules, eliminates functioning non-cystic parenchyma in some patients and spares other is a mystery. The cysts initiate in early childhood in fewer than 1% of renal tubules as a consequence of the focal expression of mutated DNA. Tubule cells proliferate, causing segmental dilation, in association with the abnormal deposition of extracellular matrix proteins. Most of the cysts separate from the parent tubules and fill with fluid by cAMP-mediated chloride secretion. Risk factors associated with accelerated loss of renal function include: genotype (PKD Type 1 progresses more rapidly than PKD Type 2); gender (males progress more rapidly than females); race (black patients progress more rapidly than whites); hypertension; proteinuria. The relation between kidney size and progression to renal failure is debated. Progressive PKD is associated with the cellular expression of proto-oncogenes (fos, myc, ras, erb), growth factors (EGF, HGF, acid and basic FGF), chemokines (MCP-1. osteopontin), metalloproteinases, and apoptotic markers, and the interstitial accumulation of Types I and IV collagen, laminin, fibronectin, macrophages and fibroblasts, the magnitudes of which increase with age. Cyst activating factor (CAF), a neutral lipid identified in cyst fluid that stimulates fluid secretion and proliferation of renal epithelial cells and monocyte chemotaxis, has recently been identified as a potential progression factor. In those patients destined to develop renal failure there is loss of non-cystic parenchyma in association with mass replacement by fluid-filled cysts in a network of interstitial fibrosis. The decline in renal function is probably the consequence of processes leading to interstitial fibrosis, as in other nephropathies, rather than due to simple mechanical displacement of parenchyma by cysts.
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PMID:Mechanisms of progression in autosomal dominant polycystic kidney disease. 940 32

We describe four prenatal diagnoses in a family with autosomal dominant polycystic kidney disease. Two pregnancies were terminated following the detection of enlarged echogenic fetal kidneys with cysts. Histopathological examination confirmed the diagnosis of polycystic kidney disease. Linkage to PKD1 was obtained by the analysis of DNA from relatives in three generations and from paraffin blocks and formalin fixed fetal tissues. Prenatal DNA analysis in subsequent pregnancies identified one unaffected fetus and one fetus carrying the high risk PKD1 allelle. Information on survival and subsequent outcome of PKD cases presenting in utero was requested by this family before prenatal testing was performed. Of 83 reported cases of ADPKD presenting in utero (excluding termination of pregnancy) or in the first few months of life, 43% died before 1 year. Longitudinal follow up of 24 children in two studies showed that 67% of survivors developed hypertension, of whom three had end stage renal failure at a mean age of 3 years.
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PMID:Prenatal diagnosis of autosomal dominant polycystic kidney disease (PKD1) presenting in utero and prognosis for very early onset disease. 947 88

We retrospectively evaluated the factors that are prognostic in long-term continuous ambulatory peritoneal dialysis (CAPD). From 1986 to 1997, 91 CAPD patients (59 male, 32 female, mean age 48 years) entered the study. Their primary renal diseases were chronic glomerulonephritis (CGN, n = 80), diabetic nephropathy (DN, n = 10), and polycystic kidney disease (PKD, n = 1). The roles of primary renal disease, hypertension, left ventricular hypertrophy (LVH), left ventricular ejection fraction (LVEF), cardiac sympathetic activity, anemia, hypoalbuminemia, and plasma concentration of parathyroid hormone (PTH) on patient prognosis were analyzed. Among the 91 CAPD patients, 26 died during the observation period. Of these deaths, 17 resulted from cardiovascular diseases including cerebrovascular events (n = 7), myocardial infarction (n = 2), sudden death (n = 7), and aortic aneurysmal rupture (n = 1). Nine patients died of non cardiovascular events. Sclerosing encapsulating peritonitis and others, mainly cachexia, accounted for 2 and 7 of these deaths, respectively. The 5-year survival rate was 74%; the 10-year rate was 49%. The cumulative 5- and 10-year success rates of CAPD were 69% and 39%, respectively. DN, hypertension, severe LVH (more than 200 g/m2), and hypoalbuminemia were contributors to poor prognosis. Among these, DN and severe LVH were the two main predictors by Cox proportional hazards model. We conclude that CAPD patients with DN or severe LVH, or both, have a greater chance of drop-out from cardiovascular events.
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PMID:Predictors of survival in continuous ambulatory peritoneal dialysis patients: the importance of left ventricular hypertrophy and diabetic nephropathy. 1068 78

Autosomal dominant polycystic kidney disease (ADPKD) is a major, inherited disorder that is characterized by the growth of large, fluid-filled cysts from the tubules and collecting ducts of affected kidneys, and by a number of extrarenal manifestations including liver and pancreatic cysts, hypertension, heart valve defects, and cerebral and aortic aneurysms. Mutations in either of 2 different genes (PKD1 or PKD2) give rise to ADPKD. Most mutations identified in affected families appear to inactivate the PKD genes, and accumulating evidence suggests that a 2-hit mechanism, in which the normal PKD1 or PKD2 allele is also mutated, may be required for cyst growth. The protein products of the PKD genes (polycystin-1 and polycystin-2) are thought to function together as part of a multiprotein membrane-spanning complex involved in cell-cell or cell-matrix interactions. Polycystin-1 and polycystin-2 can initiate signal transduction, leading to the activation of a number of downstream effectors, including heterotrimeric G-proteins, protein kinase C, mitogen-activated protein kinases, beta-catenin, and the AP-1 transcription factor. In addition, polycystin-2 may function in mediating calcium flux. The pathogenesis of cyst formation is currently thought to involve increased cell proliferation, fluid accumulation, and basement membrane remodeling. It now appears that cyclic adenosine monophosphate (cAMP) metabolism is a central component of cyst formation, stimulating apical chloride secretion and driving the accumulation of cyst fluid. Recent evidence has shown that ADPKD cells also have an altered responsiveness to cyclic AMP. In contrast to normal kidney cells whose cell proliferation is inhibited by cyclic AMP, ADPKD cells are stimulated to proliferate. Thus, it is likely that an alteration in polycystin function transforms the normal cellular phenotype to one that responds to elevated cyclic AMP by an increased rate of cell proliferation and that the enlarging cyst expands by an increased rate of cyclic AMP-driven fluid secretion. Cyclic AMP and growth factors, including epidermal growth factor, have complementary effects to accelerate the enlargement of ADPKD cysts, and thereby to contribute to the progression of the disease. This knowledge should facilitate the discovery of inhibitors of signal transduction cascades that can be used in the treatment of ADPKD.
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PMID:The genetics and physiology of polycystic kidney disease. 1124 74

Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited disorder frequently associated with renal failure, hypertension, and other abnormalities. The present study determined whether chronic caffeine intake in an animal model of this disease would affect renal structure and function and blood pressure. Heterozygous male Han:Sprague-Dawley rats with ADPKD and normal littermates were provided with either tap water or solutions of caffeine to drink, starting at 1 month of age. When rats were aged 6 months, glomerular filtration rate (GFR) and mean arterial blood pressure (MAP) were measured under Inactin (Byk Gulden, Konstanz, Germany) anesthesia. Caffeine intake had no effect on GFR or cyst development in rats with PKD. MAP was greater in rats with PKD than normal rats and was increased more by caffeine. The hypertensive effect of chronic caffeine intake could not be ascribed to direct pressor effects of angiotensin II. Based on our finding that caffeine exacerbates hypertension in rats with PKD, it may be prudent for patients with ADPKD to limit coffee consumption to four or fewer cups of caffeinated coffee per day, pending studies of humans.
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PMID:Chronic caffeine consumption exacerbates hypertension in rats with polycystic kidney disease. 1168 64

Autosomal-dominant polycystic kidney disease is a multiorgan disease and its vascular manifestations are common and life-threatening. Despite this, little is known about their pathogenesis. Somatic mutations to the normal PKD allele in cystic epithelia and cyst development associated with the unstable Pkd2(WS25) allele suggest a two-hit model of cystogenesis. However, it is unclear if this model can account for the cardiovascular pathology or if haploinsufficiency alone is disease-associated. In the present study, we found a decreased polycystin-2 (PC2, protein encoded by Pkd2 gene) expression in Pkd2( +/-) vessels, roughly half the wild-type level, and an enhanced level of intracranial vascular abnormalities in Pkd2 (+/-) mice when induced to develop hypertension. Consistent with these observations, freshly dissociated Pkd2 (+/-) vascular smooth muscle cells have significantly altered intracellular Ca(2+) homeostasis. The resting [Ca(2+)](i) is 17.1% lower in Pkd2 (+/-) compared with wild-type cells (P=0.0003) and the total sarcoplasmic reticulum Ca(2+) store (emptied by caffeine plus thapsigargin) is decreased (P<0.0001). The store operated Ca(2+) (SOC) channel activity is also decreased in Pkd2 (+/-) cells (P=0.008). These results indicate that inactivation of just one Pkd2 allele is sufficient to significantly alter intracellular Ca(2+) homeostasis, and that PC2 is necessary to maintain normal SOC activity and the SR Ca(2+) store in VSMCs. Based on these findings, and the fact that [Ca(2+)](i) signaling is essential to the regulation of contraction, production and secretion of extracellular matrix, cellular proliferation and apoptosis, we propose that the abnormal intracellular Ca(2+) regulation associated with Pkd2 haploinsufficiency is directly related to the vascular phenotype.
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PMID:Pkd2 haploinsufficiency alters intracellular calcium regulation in vascular smooth muscle cells. 1287 7

Autosomal recessive polycystic kidney disease (ARPKD) is a severe form of inherited childhood nephropathy ( approximately 1:20,000 live births) characterized by fusiform dilatation of collecting ducts and congenital hepatic fibrosis. Up to 30% die as neonates due to respiratory insufficiency and the majority of surviving infants develop hypertension. Progression to end stage renal disease occurs in 20-45% of cases within 15 years but a proportion maintain renal function into adulthood where complications of liver disease predominate. The ARPKD disease gene, PKHD1, has recently been identified through analysis of an orthologous animal model, the PCK rat. PKHD1 is a large gene ( approximately 470 kb) with 67 exons from which multiple transcripts may be generated by alternative splicing. It is highly expressed in kidney, with lower levels in liver and pancreas. The ARPKD protein, fibrocystin (4074 aa and 447 kDa), is predicted to be an integral membrane, receptor-like protein containing multiple copies of an Ig-like domain (TIG). Fibrocystin is localized to the branching ureteric bud, collecting and biliary ducts, consistent with the disease phenotype, and often absent from ARPKD tissue. In common with other PKD-related proteins, fibrocystin is localized to the primary cilia of renal epithelial cells, reinforcing the link between ciliary dysfunction and cyst development. Screens of PKHD1 have revealed 119 different mutations of various types spread throughout the gene. Several ancestral changes have been described, some localized to specific geographic populations. The majority of patients are compound heterozygotes and preliminary genotype/phenotype studies associate two truncating mutations with severe disease. The complexities of PKHD1, marked allelic heterogeneity and high level of missense changes complicate gene-based diagnostics.
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PMID:Molecular genetics of autosomal recessive polycystic kidney disease. 1474 Nov 87

Diagnosis and treatment of autosomal dominant polycystic kidney disease (ADPKD) is rapidly changing. Cellular pathways that involve the polycystins are being mapped and involve the primary cilium, intracellular calcium and cAMP regulation, and the mammalian target of rapamycin (mTOR) pathway. With the use of new imaging approaches, earlier diagnosis of hepatic cystic disease is possible, and measurement of kidney and cystic growth as well as kidney blood flow is possible over relatively short periods. PKD gene type, gender, proteinuria, and the presence of hypertension relate to the rate of kidney growth in ADPKD. On the basis of risk factors for progression to ESRD and the pathogenic roles that intracellular cAMP and mTOR play in cystogenesis, novel therapies are now being tested, including maximal inhibition of the renin-angiotensin system, inhibition of renal intracellular cAMP using vasopressin V2 receptor antagonists, and somatostatin analogues, as well as inhibitors of mTOR. This review addresses the current understanding of the pathogenesis and the natural history of ADPKD; accuracy and reliability of diagnostic approaches in utero, childhood, and adulthood; the value of reliable magnetic resonance imaging to measure disease progression early in the course of ADPKD; and novel therapeutic approaches that are being evaluated in ADPKD.
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PMID:Autosomal dominant polycystic kidney disease: time for a change? 1742 47

For determination of the incidence of renal events in autosomal dominant polycystic kidney disease (ADPKD) all patients who had ADPKD and attended nephrology/urology clinics in Newfoundland in 1981 were identified, and members of 18 families who were at 50% risk for inheriting ADPKD were followed prospectively for 22 yr, including research clinics at 6-yr intervals. Time to hypertension treatment, stage 3 chronic kidney disease (CKD), ESRD, and death was measured, and the impact of genotype, gender, gender of parent who transmitted PKD, family, family history of essential hypertension, parity, and oral contraceptive pill was assessed. Nine (50%) families had PKD1, four (22%) had PKD2, and one had both PKD1 and PKD2. The number of family members with PKD1 was 136 and with PKD2 was 60. In PKD1 median age to hypertension treatment was 46 yr, to CKD stage 3 was 50 yr, to ESRD was 53 yr, and to death was 67 yr. In PKD2, median age to hypertension treatment was 51 yr, to CKD stage 3 was 66 yr, to death was 71 yr, and ESRD was infrequent. Although the incidence of CKD was later and ESRD occurred infrequently in PKD2 compared with PKD1, early onset of hypertension occurred and life expectancy was compromised. Genotype, family, and proteinuria were identified as risk factors for incident renal events. Gender, gender of parent who transmitted PKD, family history of essential hypertension, multiparity, and use of the oral contraceptive pill were not identified as risk factors for renal events in ADPKD.
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PMID:Incident renal events and risk factors in autosomal dominant polycystic kidney disease: a population and family-based cohort followed for 22 years. 1769 77


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