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Biomedical subjects

J C Peña

Publications and source records attributed to J C Peña.

At least 19 recordsLinked to original sources
PubMed1996

Adynamic bone lesion in renal transplant recipients with normal renal function.

Adynamic bone lesion has been defined as low bone turnover, normal or low osteoid volume and decreased bone formation rate (BFR). A prospective cross-sectional study was performed in 16 asymptomatic post-transplant kidney patients with normal renal function, to evaluate low bone mineral density. The mean age of the nine women and seven men was 33.9 +/- 7.3 years, the mean serum creatinine was 1.1 +/- 0.2 mg/dl and the mean creatinine clearance 71.5 +/- 13.8 ml/min/1.73 m2. Six patients received triple immunosuppressive therapy for a period of 10.3 +/- 3.7 months and nine received double therapy. Eighty-four months after renal grafting, we carried out bone densitometry, biochemical markers and bone biopsy. Bone densitometry showed 78 +/- 8.7% and 80.4 +/- 8% for hip and lumbar spine, with a mean Z score of 1.79 +/- 0.72 and 1.88 +/- 0.78 (SD), significantly less than normal in the Hispanic young population for those two regions. Serum PTH (0.83 +/- 0.23 microgram/ml normal range 0.32-0.65), urine cAMP (4.1 +/- 1.3, normal range 0.5-4.7 nmol/mg Cr) and total and nephrogenic fraction (3.1 +/- 1.1, normal range 0.29-2.9 nmol/100 ml GFR) were significantly greater than normal (P < 0.01). The bone biopsy in 12/16 patients showed decreased percentage osteoid area (1.59 +/- 0.86% vs 3.19 +/- 0.82%), percentage mineralized area (13 +/- 4.7% vs 21.03 +/- 3.36%) and bone formation rate (505 +/- 237 vs 1275 +/- 168 microns2/mm2/day), with a P value < 0.05 compared with 10 normal bone biopsies. The remaining four patients exhibited low bone turnover image with normal bone formation rate (1442 +/- 206 microns2/mm2/ day). Iron deposits were demonstrated at the mineralization front in 10/16 patients. No aluminium or amyloid deposits were observed. The histomorphometric results showed the presence of adynamic bone lesion in 12 renal transplant recipients with normal renal function and osteopenia, which explains the low bone density. The long-term use of glucocorticoids and the presence of iron deposits may contribute to this bone lesion. The biochemical markers of bone remodelling showed abnormalities compatible with moderate increase in parathyroid function. The adynamic lesion in the presence of hyperparathyroid function may suggest down-regulation of PTH bone receptors, alterations of the bone microenvironment or both.

Adult↗
PubMed1993

Death risk in CAPD patients. The predictive value of the initial clinical and laboratory variables.

The characteristics, survival rate and risk factors associated with death in patients with end-stage renal failure treated with chronic ambulatory peritoneal dialysis (CAPD) were studied. This is a retrospective study of a cohort of 206 patients, from which the follow-up was complete in 190 patients (92%). Only 16 patients (8%) were lost. The study group is composed of 118 males and 88 females, with a mean age of 39 +/- 15 years. The origin of the renal disease was: unknown in 90 patients (44%); diabetes mellitus in 50 (24%); systemic lupus erythematosus in 16 (8%); obstructive uropathy in 15 (7%); glomerulonephritis in 14 (7%), and miscellaneous in 21 (10%). The average follow-up was 12 +/- 11 months. At the end of study, 66 patients were dead (32%). CAPD was discontinued in 12 (6%). Thirty-eight patients (18%) received kidney transplantation. The survival rate for the whole group was 67 and 48% at 1 and 3 years, respectively. Multivariate survival analysis according to the Cox proportional-hazard model showed that the most powerful predictor associated with high risk of death was low serum albumin levels. According to the Cox model other independent variables significantly associated with increase in the probability of death while on CAPD were advancing age, low serum creatinine concentrations and elevated serum cholesterol levels. These results indicate that the risk factors associated with death in CAPD patients are similar to those observed for hemodialysis patients and suggest that using simple laboratory measurements at the enrollment in CAPD the relative risk of death for each patient can be estimated.

Adolescent↗
PubMed1993

Electrophoretic analysis of serum and urinary proteins in rats with aminonucleoside-induced nephrotic syndrome.

Albumin; and alpha 1-, alpha 2-, beta-, and gamma-globulins were estimated by cellulose acetate electrophoresis in the serum and urine from rats with nephrotic syndrome (NS), 2, 4, 6, 8, 10, 12, 16, 20, and 30 days after a single injection of puromycin aminonucleoside (PAN). It was found that: (a) total serum protein level decreased on days 4-16, and total urine protein excretion rose on days 6-16; (b) serum albumin level fell on days 4-16, and urine albumin excretion increased on days 6-16; (c) serum alpha 1-globulin level rose on days 8-30, and urine alpha 1-globulin excretion increased on days 8-16; (d) serum alpha 2-globulin level remained essentially unchanged, and urine alpha 2-globulin excretion rose on days 4-10; (e) serum beta-globulin level decreased on days 4-20, and urine beta-globulin excretion increased on days 6-16, (f) serum gamma-globulin level diminished on days 6, 8, and 12, and urine gamma-globulin excretion rose on days 6-10. All serum protein fractions were excreted in the urine of nephrotic rats; these findings suggest that proteinuria is nonselective. The differences observed in the serum protein profiles, even when all protein fractions were lost in the urine, suggest an independent regulation of each protein fraction in PAN-nephrotic rats. In addition, the electrophoretic profile of serum proteins in PAN-nephrotic rats is different from previously reported patterns in human nephrosis and in rats with an acute-phase response.

Animals↗
PubMed1993

Angiotensin I-converting enzyme activity in rats with carbon tetrachloride-induced acute renal failure.

The angiotensin I-converting enzyme (ACE) activity was measured in urine, serum, and tissues from rats with carbon tetrachloride (CCl4)-induced acute renal failure on days 1, 2, 3, and 7 after CCl4 administration. Serum ACE increased on days 1 to 3. Heart, lung, small intestine, brain, and testis ACE decreased, whereas kidney and liver ACE remained unchanged. Urine ACE activity increased from day 1 to day 3. Our data suggest that the increase in serum ACE may be secondary to the ACE release from the damaged tissues, and that the urine ACE increase may be due to the kidney proximal tubule damage. This work supports the contention that an increase in urine ACE may be an indicator of damage to the proximal tubule.

Acute Kidney Injury↗
PubMed1992

[Inadequate demand in a pediatric hospital emergency department: factors involved].

BACKGROUND: The massification of pediatric hospital emergency departments (PED) is due to bad use of the same by a large number of users. The causes related with this inadequate use have not been properly evaluated. METHODS: A sample representative of the population demanding medical care in a PED of a regional hospital was studied with the motives and sociodemographic and cultural factors presumably related with this inadequate demand being analyzed. RESULTS: 52% of the cases had had no previous contact with the primary level of health care and 79% had gone to the PED on their own initiative. With regard to consultations, 65.0 +/- 4.8% were catalogued as inadequate and a statistical relation was found with the age of the patient (less than one year), place of residence (urban) and the arrival by initiative of the patients themselves. CONCLUSIONS: Pediatric hospital emergency departments receive a high number of inadequate consultations at the second level of health care. The importance of the age of the patient, accessibility of pediatric hospital emergency departments and who takes the initiative to come must be emphasized as predictive variables of the bad use of these pediatric departments.

Child↗
PubMed1992

Captopril magnifies the increase in angiotensin I-converting enzyme activity in rats with aminonucleoside nephrosis.

1. Serum, tissue and urine angiotensin I-converting enzyme (ACE) activity was estimated in the following groups of rats: saline-injected rats (controls); captopril-treated (CAP) control animals (CONTROL-CAP); puromycin aminonucleoside (PAN)-induced nephrotic syndrome (NS); and CAP-treated animals with NS (NS-CAP). 2. Serum ACE activity increased in the CONTROL-CAP, NS, and NS-CAP groups. The increase in the NS-CAP group was significantly higher compared with the NS or CONTROL-CAP groups. 3. In the CONTROL-CAP group, tissue ACE decreased in brain, heart and adrenal glands, and remained unchanged in the lung, testis, kidney, small intestine and liver. In the NS group, tissue ACE activity increased in the lung and testis, decreased in the brain and heart, and remained unchanged in the small intestine, adrenal glands, kidney and liver. Tissue ACE activity increased significantly in the NS-CAP group compared with the other groups. This increase in tissue ACE may contribute to an increase in the serum ACE activity in the NS-CAP group compared with the NS group. 4. Urine ACE activity increased in the NS and NS-CAP groups, although the rise in the NS-CAP group was significantly higher. The urine ACE correlated significantly with the circulating levels of this enzyme in the NS and NS-CAP groups. The loss of ACE in the urine in the presence of an increased serum ACE activity indicates that the biosynthesis of tissue ACE and its release into the bloodstream must be elevated.

Animals↗
PubMed1992

Effect of captopril on urinary excretion of renin and angiotensinogen in aminonucleoside nephrosis.

Puromycin aminonucleoside (PAN)-nephrotic rats show high plasma renin, low plasma angiotensinogen (Angt), and increased urinary excretion of renin and Angt. In this work, we studied the effect of captopril on urinary excretion of total protein, renin, and Angt for 25 days after PAN injection. Captopril had no effect on total protein urinary excretion; however, captopril did enhance the urinary excretion of renin and did decrease the urinary excretion of Angt. This seems to be due to the fact that captopril magnifies the increase in renin and the decrease in Angt in the plasma of PAN-nephrotic rats.

Angiotensinogen↗
PubMed1992

Activity of serum enzymes in puromycin aminonucleoside-induced nephrotic syndrome.

Total serum protein, serum albumin, total urine protein excretion, and the serum activity of several enzymes--aldolase (ALS), cholinesterase (CHS), leucine aminopeptidase (LAP), isocitrate dehydrogenase (ICD), aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), alpha-hydroxybutyrate dehydrogenase (HBD), creatine kinase (CK), alkaline phosphatase (ALP), and gamma-glutamyl transferase (GGT)--were estimated in rats with nephrotic syndrome (NS) at 2, 4, 6, 8, 10, 12, 16, 20, and 30 days after a single injection of puromycin aminonucleoside (PAN). It was found that: (a) total serum protein and serum albumin diminished on day 4 and returned to control values on days 20 and 30, respectively; (b) total urine protein excretion rose on day 4, reached a peak value on day 8, and then fell substantially but still remained higher than control values on day 30; (c) ALS and CHS activities increased; (d) LAP, ICD, and AST activities showed a biphasic pattern, first increasing and then decreasing; (e) ALT, LDH, HBD, CK, and ALP activities decreased; and (f) GGT activity remained unchanged. The differences in the profiles of the enzyme activities suggest their independent regulation in experimental NS induced by PAN.

Animals↗
PubMed1991

Observer agreement in the scoring of the activity and chronicity indexes of lupus nephritis.

The present study was designed to evaluate the observer reliability in the scoring of the activity and chronicity indexes, among three experienced pathologists, in renal biopsies from lupus nephritis (LN). Twenty-five renal biopsies of LN, were evaluated independently by three pathologists to assess the interobserver variability. For the intraobserver agreement, 5 biopsies were evaluated twice by each pathologist. The interobserver agreement for the scoring of the activity and chronicity indexes was 0.81 and 0.86, respectively. In the intraobserver agreement the same results were: for the pathologist 1, 0.95 and 0.70; for the pathologist 2, 0.91 and 0.55; for the pathologist 3, 0.89 and 0.82. In conclusion the agreement for the scoring of the activity and chronicity indexes in biopsies from LN was excellent.

Acute Disease↗
PubMed1991

Urinary excretion of renin and angiotensinogen in nephrotic rats.

Puromycin aminonucleoside (PA)-nephrotic rats have a high plasma renin activity (PRA) and low angiotensinogen levels. We measured proteinuria, urine renin, and urine angiotensinogen daily, for 11 days after PA injection. Proteinuria and urine angiotensinogen were evident on day 5, and urine renin on day 6. Peak levels of urine renin and angiotensinogen were attained on day 8. These data suggest that angiotensinogen urine excretion may contribute to its low plasma levels, and urine renin loss may limit a further increase in PRA.

Angiotensinogen↗
PubMed1990

Serum angiotensin converting enzyme activity and plasma renin activity in experimental models of rats.

1. Serum angiotensin converting enzyme activity (ACEA) and plasma renin activity (PRA) were determined in rats under different experimental conditions such as: nephrotic syndrome (NS), bilateral nephrectomy (BN), renovascular hypertension (RH), dehydration (DEH), anaesthesia (AN), low sodium diet (LSD) and high sodium diet (HSD), and injection with propranolol (PRO) and isoprenaline (ISO). 2. PRA increased in LSD, AN, NS, RH, DEH and IPT groups, and decreased in HSD, BN, and PRO groups. Serum ACEA did not change in RH, HSD, IPT, DEH, AN, and PRO groups, increased in NS group, and decreased in LSD and BN groups. 3. Serum ACEA changed in the opposite direction to PRA only in the LSD group. This finding suggests that ACE may limit the full expression of the renin-angiotensin system in the LSD group, but not in the other groups.

Animals↗
PubMed1989

Evaluation of nutritional status in patients on continuous ambulatory peritoneal dialysis (CAPD).

We designed this study to evaluate the nutritional conditions of 16 continuous ambulatory peritoneal dialysis (CAPD) patients. In all these patients we did a monthly 1-day clinical, anthropometrical, biochemical, and nitrogen balance evaluation: a minimum of 3 and a maximum of 9 monthly evaluations in all patients. The results were analyzed in two groups: Group I (N = 8) with neutral or positive nitrogen balances, and Group II (N = 8) with one or more negative nitrogen balances. The sex distribution, mean age in years, time on CAPD, and period of study in this protocol were similar in both groups. Group I maintained a positive nitrogen balance and steady values in the anthropometric measurements (triceps fat fold, upper-arm circumference, body weight). Group II showed a significant decrease in both the anthropometric values and the nitrogen balance during the episodes of peritonitis. In this same group, when peritonitis subsided, the protein intake increased, nitrogen balance became positive, and the anthropometric values improved. When all the nutritional evaluations were analyzed we found a significant and direct linear correlation between nitrogen intake and nitrogen balance in g/kg/day (N = 60; nitrogen balance = nitrogen intake x 0.75 - 0.101; r = 0.71; p less than 0.001). We also contrasted the presence of peritonitis with the nitrogen balance and the anthropometric values using Spearman rank correlation coefficient and obtained a very high correlation (0.997 to 0.999). Blood values (blood urea, serum creatinine, serum phosphate, serum potassium, and hemoglobin) were not very sensitive to detect differences within or between groups along the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

The role of oxalate and calcium oxalate activity and formation product ratio in patients with renal stones before and during treatment.

The participation of oxalate in nephrolithiasis was evaluated in 202 stone patients. The activity product and formation product ratios of calcium oxalate were substantially altered in the stone population. Treatment with thiazide derivatives and/or allopurinol was able to decrease urine oxalate and normalize the activity product and formation product ratios. Stone activity decreased in the stone population after treatment. Our data suggest that oxalate may have a critical role in nephrolithiasis activity.

Allopurinol↗