PubMed Health⌕ Search

Biomedical subjects

A Andres

Publications and source records attributed to A Andres.

At least 55 records · Page 3Linked to original sources
PubMed1995

Impairment of the liver insulin receptor autoactivation cascade at full-term pregnancy in the rat.

Partially purified liver insulin receptors from full-term pregnant rats show decreased autophosphorylation rates if compared with receptors from virgins. We studied the molecular mechanism of this phenomenon, looking at possible structural and functional changes of several domains. The ATP-binding domain seems to be unaltered in receptors from pregnant rats since Km for ATP was similar to that observed in virgins. In contrast, the Vmax. is decreased some 45%, suggesting changes in the kinase domain. Truncation of a fragment of 10 kDa from the C-terminal tail does not normalize the kinase activity in receptors from pregnant rats, suggesting that this domain is not involved in the inhibitory regulation. Treatment with alkaline phosphatase increases the [32P]Pi incorporation into receptors from pregnant rats; however, the autophosphorylation remains lower than that observed in virgin rats. Tryptic phosphopeptide maps of phosphorylated receptors show that the same phosphopeptides are present in receptors from virgin and pregnant rats. However, the progression through the autoactivation cascade in the kinase domain is impaired in receptors from pregnant rats. Differences in the cleavage by trypsin at the two alternative sites in the kinase domain were observed, indicating possible structural changes in receptors from pregnant rats that could be related to the impairment of the autoactivation cascade. Integrity of the alpha- and beta-subunits, as well as differential expression of the two receptor isotypes, were shown to be unaltered. We conclude that (1) the decreased autophosphorylation rate of the liver insulin receptor from pregnant rats is associated with the impairment of its autoactivation cascade, probably as a consequence of the basal Ser/Thr phosphorylation; and (2) the inhibition of the autoactivation cascade does not account for the overall inhibition of autophosphorylation observed in receptors from pregnant rats.

Adenosine Triphosphate↗
PubMed1995

Transplantation of kidneys from donors with hepatitis C antibody into recipients with pre-transplantation anti-HCV.

Hepatitis C virus (HCV) is transmitted by organ transplantation. Consequently, several organ procurement organizations have imposed a moratorium on use of organs from anti-HCV positive donors. Because of the inadequate supply of cadaver kidneys for transplantation, we adopted a policy to transplant kidneys from anti-HCV donors into anti-HCV positive recipients. During the period between March 1990 and December 1992, 24 anti-HCV positive dialysis patients received a kidney from anti-HCV positive donors (group I) and 40 anti-HCV positive patients received a kidney from anti-HCV negative donors (group II). We compared the prevalence of liver disease, anti-HCV, HCV RNA, graft and patient survival between groups. Pre-transplantation 17 of 24 (71%) patients in group I and 31 of 40 (79%) of patients in group II had serum HCV RNA. Post-transplantation follow-up was 26 +/- 8 months and 30 +/- 10 months in groups I and II, respectively. During follow-up, elevated ALT levels were present in 7 of 24 (29%) and 16 of 40 (40%) of patients in groups I and II, respectively (P > 0.05). Post-transplantation, all patients in both groups retained anti-HCV. The prevalence of HCV RNA post-transplantation was 22 of 23 (96%) patients in group I and 30 of 39 (77%) of patients in group II (P > 0.05). Graft and patient survival in group I (96% and 100%, respectively) were not significantly different from those in group II (93% and 98%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Natriuretic effects of dopamine agonist drugs in models of reduced renal mass.

In addition to recognized neurotransmitter properties in the central nervous system, dopamine (DA) plays a role in the physiological activity of the kidney through its hemodynamic and natriuretic effects. On the basis of these data, some pharmacological interventions have focused their attention on the use of DA-related drugs to improve renal sodium handling. We summarize the data obtained from two studies using two DA agonist drugs, lisuride (LIS) and fenoldopam (FEN), in two situations of reduced renal mass. During an intravenous sodium load performed on 10 uninephrectomized dogs, LIS induced a significant blockade of the concomitant pressor response, estimated by lower blood pressure and norepinephrine levels. Under these same conditions, FEN significantly decreased blood pressure and elevated the natriuretic response. In a second study, when FEN was administered at nonhypotensive doses to chronic renal failure patients, it evoked an enhancement of diuresis, natriuresis, and creatinine clearance. These data seem to confirm the involvement of DA in the regulation of cardiovascular homeostasis and its role in renal sodium handling. Furthermore, these beneficial effects support the use of DA-related drugs in the field of hypertension.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1993

Encrusted pyelitis and cystitis by Corynebacterium urealyticum (CDC group D2): a new and threatening complication following renal transplant.

We evaluated the pathogenic role of Corynebacterium urealyticum in the development of encrusted pyelitis (EP) and encrusted cystitis (EC), and their clinical consequences in renal transplant recipients. During a 4-year period, we studied seven renal transplant recipients with EP and two with EC. The records of 320 other renal transplant patients studied during the same period were used as a control group. C urealyticum (> or = 10(5) CFU/ml) was isolated from 4 patients with EP (urine 3, blood 1) and from 1 patient with EC (urine). Alkaline urines with struvite crystals, microscopic hematuria, and sterile conventional urine cultures were present in all our cases. All the patients with EP developed obstructive uropathy with deterioration of the renal function and pyelonephritis (4 patients) or renal abscesses (3 patients). Chronic urinary discomfort and macroscopic hematuria were present in the 2 patients with EC. Long-term vesical and ureteral catheterization were considered the most important risk factors for the development of EC and EP, respectively. Vancomycin was successfully used in 5 cases, but all the patients required a derivative procedure or a surgical resection of the incrustations to improve. We conclude that EP and EC should be investigated in renal transplant patients who develop pyelonephritis, obstructive uropathy, or chronic urinary symptoms. EP and EC could lead to the loss of their grafts. C urealyticum appears to have a pathogenic role in these entities.

Adult↗
PubMed1993

Compressive myelopathy due to dialysis-associated amyloidosis.

A 66-year-old woman presented a spastic quadriparesis due to compression of the cervical cord 6 years after the beginning of chronic hemodialysis. Five years later, she developed a second episode of compressive myelopathy affecting the lumbar spine. On both occasions, surgical laminectomy with removal of fibroligamentous rings that compressed the cord led to a total recovery of the patient. Histological study demonstrated the presence of massive amyloid deposits in the surgically excised material.

Aged↗
PubMed1992

Regulation of cyclic AMP synthesis and degradation is modified in rat liver at late gestation.

Cyclic AMP (cAMP) is known to play a key role in regulating insulin action, and it is well documented that in several cases of physiological insulin resistance its concentration is increased. Since late pregnancy in the rat is associated with liver insulin resistance, we have studied possible alterations of some cellular mechanisms regulating the cAMP metabolism. (1) Liver cAMP concentration was shown to be increased by some 30% and 50% at 18 and 22 days of pregnancy respectively, compared with virgins. (2) Basal adenylate cyclase activity was higher only in the 18-days-pregnant rat, and the forskolin-stimulated maximal activity was similar in the three groups of animals. (3) alpha s protein is decreased in term-pregnant rats; however, coupling between Gs and adenylate cyclase is only impaired in the 18-days-pregnant animals, and stimulation by glucagon is impaired in both groups of pregnant animals. (4) Gi-2 protein was shown to be unable to elicit the tonic inhibition of adenylate cyclase in pregnant rats, although it was only decreased at 22 days of gestation. The increased alpha i-2 level detected by immunoblotting at 18 days of gestation did not correlate with its decreased ADP-ribosylation, suggesting that the protein is somehow modified at this stage. (5) Pregnancy is associated with a decrease in membrane phosphodiesterase activity. Our results show that late pregnancy is associated with increases in liver cAMP levels that might be involved in eliciting the characteristic insulin-resistant state, and suggest that mechanisms leading to these increments are changing during this phase of gestation.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1991

Nephrotic proteinuria without hypoalbuminemia: clinical characteristics and response to angiotensin-converting enzyme inhibition.

Although hypoalbuminemia is a fundamental characteristic of nephrotic syndrome (NS), there are many patients with massive proteinuria that do not develop hypoalbuminemia. We have studied the clinical and biochemical characteristics of 19 patients with persistent massive proteinuria (greater than 5 g/d) and normal serum albumin (group I) in comparison with 16 patients with similar proteinuria excretion, but persistent hypoalbuminemia (group II). Most of group I patients had diagnoses suggesting glomerular hyperfiltration (focal glomerulosclerosis [FGS] associated with vesicoureteral reflux [VUR], reduction of renal mass, proteinuria associated with obesity, sclerotic phase of idiopathic crescentic glomerulonephritis [GN] in contrast with those of group II, in which membranous GN was the most frequent diagnosis. We prospectively investigated differences in the antiproteinuric effect of captopril, an antiotensin-converting enzyme inhibitor (ACEI); after 6 months of treatment, proteinuria decreased clearly in group I (7.1 +/- 1.7 to 3.7 +/- 1.7 g/d; P less than 0.001), whereas no significant changes were observed in group II (8.1 +/- 2.4 to 8.8 +/- 4 g/d). Serum creatinine (Scr) remained stable during captopril treatment in group I, whereas three patients in group II showed a worsening of renal function.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylglucosaminidase↗