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Biomedical subjects

A Guerra

Publications and source records attributed to A Guerra.

At least 55 records · Page 3Linked to original sources
PubMed1999

Urine volume: stone risk factor and preventive measure.

BACKGROUND: A high fluid intake is the oldest existing treatment for kidney stones, and, up until a few decades ago, it was the only preventive measure at the physician's disposal for stone recurrences. METHODS: Using the data available in literature and partly unpublished personal research, we examine the role of urine volume as a stone risk factor, its impact on calcium crystallization mechanisms and its real importance as a means of prevention. RESULTS: To sum up, the most important findings are: (1) a low urine volume must be considered as a real risk factor, both as regards the onset of renal calculi and stone relapses; (2) an increase in urine volume induced by a high water intake produces favourable effects on the crystallization of calcium oxalate and does not reduce the activity of natural inhibitors; (3) a sufficiently high intake of water and probably other fluids such as coffee, tea, beer and wine has a preventive effect on nephrolithiasis and its recurrence, and (4) the role of fruit juice is still to be defined. CONCLUSIONS: A high intake of fluids, especially water, is still the most powerful and certainly the most economical means of prevention of nephrolithiasis, and it is often not used to advantage by stone formers.

Calcium↗
PubMed1998

Cutaneous metastasis from a presumed signet-ring cell carcinoma in a 10-year-old child.

Cutaneous metastases of internal malignancies are very rare in children. In this group, neuroblastoma, leukaemia and lymphoma are the most common malignancies that may develop metastases or neoplastic infiltrates to the skin. Carcinomas have infrequently been reported in children, and cutaneous metastases from carcinoma in this group have not been described. A 10-year-old girl presented with an erythematous plaque on the left hemithorax. Histopathological findings revealed grouped signet-ring cells within the lumina of lymphatic vessels in the dermis. Immunohistochemical examination confirmed the epithelial origin of the tumour. Despite an exhaustive search, the primary site could not be determined. This exceptional observation is, to the best of our knowledge, the first report of cutaneous metastasis from occult carcinoma in a child.

Carcinoma, Signet Ring Cell↗
PubMed1998

Growth hormone reduces mortality and bacterial translocation in irradiated rats.

Growth hormone stimulates the growth of intestinal mucosa and may reduce the severity of injury caused by radiation. Male Wistar rats underwent abdominal irradiation (12 Gy) and were treated with either human growth hormone (hGH) or saline, and sacrificed at day 4 or 7 post-irradiation. Bacterial translocation, and the ileal mucosal thickness, proliferation, and disaccharidase activity were assessed. Mortality was 65% in irradiated animals, whereas hGH caused a decrement (29%, p < 0.05). Bacterial translocation was also reduced by hGH (p < 0.05). Treating irradiated rats with hGH prevented body weight loss (p < 0.05). Mucosal thickness increased faster in irradiated hGH-treated animals. The proliferative index showed an increment in hGH-treated animals (p < 0.05). Giving hGH to irradiated rats prevented decrease in sucrose activity, and increment in lactase activity. In conclusion, giving hGH to irradiated rats promotes the adaptative process of the intestine and acute radiation-related negative effects, including mortality, bacterial translocation, and weight loss.

Abdomen↗
PubMed1998

Cardiac valve calcification in haemodialysis patients: role of calcium-phosphate metabolism.

BACKGROUND: Cardiac valve calcification (VC) has been detected with increased frequency in haemodialysis (HD) patients, making it necessary to determine the potential pathogenic factors in uraemic patients. METHODS: A total of 92 chronic HD patients (39 female, 53 male) and 92 age and gender-matched nondialysis control subjects were evaluated by echocardiography and a severity score for VC was determined. Calcium phosphate metabolism was evaluated at the beginning of haemodialysis. RESULTS: We found a greater prevalence of VC in dialysis patients than in normal patients (mitral annulus 44.5% vs 10%, P = 0.02; aortic annulus 52% vs 4.3%, P = 0.01). HD patients with mitral calcification were found to be older than patients without calcification, were on long-term renal replacement therapy, had longer duration of predialysis arterial hypertension, had greater values of the highest value of mean calcium phosphate product in 6 successive months (CaxP) and the highest absolute value of calcium-phosphate product (CaxPmax). We also found a positive correlation between calcification score, age, and CaxP. No correlation was found between actual VC and arterial hypertension or parathyroid hormone. Multiple stepwise regression analysis selected age and CaxP as the most predictive parameters for mitral calcification (r = 0.47). Mitral calcification was associated more frequently with rhythm and cardiac conduction defects, valvular insufficiency and with peripheral vascular calcification. Aortic calcification was correlated with age (r = 0.42) and longer duration of predialysis arterial hypertension. CONCLUSION: Our study confirmed an increased prevalence of VC in HD patients and selected age and calcium phosphate product as the most predictive parameters. These findings support careful monitoring of calcium metabolism beginning at the early stages of end-stage renal failure to reduce the risk of heart disease.

Aged↗
PubMed1998

Modulation of 72-kilodalton type IV collagenase (Matrix metalloproteinase-2) by ascorbic acid in cultured human amnion-derived cells.

Extensive research has been done to investigate the effects of nutrients on placental and fetal development. It is now evident that environmental factors such as diet may exert a profound effect on gene expression during pregnancy. A low intake of vitamin C during pregnancy has been linked to a higher risk of premature rupture of the membranes (PROM) because of its well-known role in collagen biosynthesis. Here we report a new effect of ascorbic acid acting as a modulator of the 72-kDa type IV collagenase (matrix metalloproteinase-2; MMP-2). MMP-2 expression/activity is down-regulated by vitamin C in human amnion cultured cells. The regulatory effect is exerted at the transcriptional level and is specific for MMP-2. Matrix metalloproteinases are implicated in tissue remodeling, and our results allow us to suggest a molecular mechanism that relates poor availability of vitamin C during pregnancy and the development of PROM.

Amniotic Fluid↗
PubMed1998

Multivariate analysis of prognostic factors in resected colorectal cancer: a new prognostic index.

OBJECTIVE: We analysed different clinicopathological variables in colorectal cancer and their independent prognostic significance in order to elaborate a prognostic index, which may be used to categorize patients into homogeneous groups and indicate adjuvant therapy. DESIGN: Retrospective study. METHODS: Patients (n = 108) undergoing surgery for colorectal cancer were studied (5-year-survival was controlled). Different clinicopathological variables and biological parameters (tumoural ploidy, proliferating cell nuclear antigen PCNA and nucleolar organizing regions NORs) were analysed. The Kaplan-Meier method and log-rank test were used for univariate analysis and the Cox regression method was used for multivariate analysis. RESULTS: Some variables with prognostic effect in univariate analysis (e.g. rectal bleeding, altered bowel habit, intestinal obstruction, type of surgery, histological type, venous and neural invasion and invasive margin) did not have independent prognostic significance after Cox analysis. Final multivariate analysis model was defined by five parameters: postoperative carcinoembryonic antigen, Astler-Coller-Turnbull staging, histological grade, lymphatic invasion and tumour ploidy. A new prognostic index was elaborated that provided information to group patients in three prognostic categories of different risk: high, medium and low. CONCLUSION: The prognostic index allowed categorization of patients into different risk groups with identical tumoural stage and histological grade. Therefore, this index provides better prognostic information that may be helpful when selecting patients for adjuvant therapy.

Adenocarcinoma↗
PubMed1998

Compound heterozygosity for a new (S259G) and a previously described (G188E) mutation in lipoprotein lipase (LpL) as a cause of chylomicronemia. Mutations in brief no. 183. Online.

Familial chylomicronemia is an autosomal recessive disease characterised by fasting triglyceridemia and an absence of lipoprotein lipase (LpL) activity in post-heparin plasma. The disease is a result of mutation in either the lipoprotein lipase (Lpl) gene or in the apoCII gene which codes for an essential co-factor. To date, over 80 mutations in the LpL gene have been reported. The proband, a 30 month old female, presented with fasting triglycerides of 3192 mg/dl, and no detectable LpL mass or activity in post-heparin plasma. Sequencing of all of the exons and exon/intron boundaries of the LpL gene showed that she was a compound heterozygote with G-A transitions in codon 188 (G188E:GGG to GAG) generating an avall restriction site and in codon 259 (S259G:AGT to GGT) generating a bssKI site. Restriction digests confirmed the mutations and determined the incidence within the family. The father (55%LPL activity), paternal aunt (82%) and paternal grandmother (29%) were all heterozygous for the S259G mutation whilst her sister (55%), mother (73%) and maternal grandfather (45%) were heterozygous for the G188E mutation. The maternal grandmother (114%) was unaffected.

Female↗
PubMed1998

Growth hormone reduces bacterial translocation in radiation enteritis in the rat.

BACKGROUND: Radiotherapy may be considered as one of the most effective treatments for digestive tumours. This procedure has major side effects, especially in fast growing tissues like intestinal mucosa. The administration of drugs that reduce or avoid radiation injury of the intestinal mucosa may be clinically advantageous. Growth hormone is a peptide suitable for this purpose by modifying cell proliferation within the intestinal crypt. MATERIAL AND METHOD: Adult male Wistar rats were used in a model of abdominal irradiation. Each irradiated animal received 1200 cGy under anaesthesia and was sacrificed four and seven days later. The animals were treated with either saline or growth hormone (1 mg/kg/day) beginning immediately after the irradiation treatment. On the day of sacrifice, intestinal samples were taken for morphometric measurements and mesenteric lymph nodes for bacterial translocation. RESULTS: Mortality was of 50% approximately and was not affected by growth hormone treatment in irradiated animals. Bacterial translocation increased (p < 0.05) in irradiated animals whereas no significant increase was observed in rats treated with growth hormone. Growth hormone promotes an earlier growth of intestinal villi in irradiated animals (p < 0.05). CONCLUSIONS: Growth hormone promotes the morphologic adaptation of intestinal mucosa after abdominal irradiation, reducing bacterial translocation in rat.

Animals↗
PubMed1997

Genetic and environmental factors regulating blood pressure in childhood: prospective study from 0 to 3 years.

OBJECTIVES: Blood pressure (BP) regulation depends on the interaction between multiple environmental and genetic factors. Of these, BP sensitivity to dietary sodium intake has been one that has been investigated in adults but not in children. The aim of the present study was to investigate, prospectively, the BP profile in relation to different genetic and hormonal factors, in the first 3 years of life. POPULATION AND METHODS: Thirty-nine children born at term following normal pregnancies, with uncomplicated neonatal periods, were randomly selected to take part in the study. BP, weight and length were evaluated every 3 months from birth to 3 years. At the age of 12 months, haptoglobin phenotypes and plasma active renin concentration were determined as well as random urine evaluation of aldosterone, cAMP, dopamine and digoxin-like immunoreactive substances (DLIS). Family history of cardio-vascular diseases was also recorded. RESULTS: Systolic BP (SBP) demonstrated a gradual increase until the age of 6 months with little variation up to 36 months. Tracking of SBP values was also observed from the first year as infants with high values (above the 75 percentile) maintained this tendency up to, at least, the age of 36 months. The comparison between SBP and diastolic BP (DBP) according haptoglobin phenotypes demonstrated that SBP was systematically higher in allele 1, with apparently an increasing tendency with age, although the differences did not have statistical significance. The comparative study between haptoglobin phenotypes, with correction for the covariates fractional excretion of sodium and potassium, showed that allele 1 carriers had significantly lower plasma renin and urine aldosterone and cAMP concentrations than allele 2, but dopamine excretion was found to be higher in allele 1 than in allele 2. There were no differences among variables relating to family history of cardiovascular disease. CONCLUSIONS: There was an early tracking process of BP values from the first 6 months of life which persists through, at least, to the age of 36 months. Differences in sodium handling between haptoglobin 1 and 2 phenotypes were already present in early childhood, although no significant repercussion in BP values could be demonstrated in the 3-year duration of this study.

Age Factors↗
PubMed1997

Hypoxanthine phosphoribosyltransferase from Trypanosoma cruzi as a target for structure-based inhibitor design: crystallization and inhibition studies with purine analogs.

The hypoxanthine phosphoribosyltransferase (HPRT) from Trypanosoma cruzi is a potential target for enzyme structure-based inhibitor design, based on previous studies which indicate that these parasites lack the metabolic enzymes required for de novo synthesis of purine nucleotides. By using a bacterial complement selection system, 59 purine analogs were assayed for their interaction with the HPRTs from T. cruzi and Homo sapiens. Eight compounds were identified from the bacterial assay to have an affinity for the trypanosomal enzyme. Inhibition constants for four of these compounds against purified recombinant trypanosomal and human HPRTs were determined and compared. The results confirm that the recombinant system can be used to identify compounds which have affinity for the trypanosomal HPRT. Furthermore, the results provide evidence for the importance of chemical modifications at positions 6 and 8 of the purine ring in the binding of these compounds to the HPRTs. An accurate three-dimensional structure of the trypanosomal enzyme will greatly enhance our understanding of the interactions between HPRTs and these compounds. Toward this end, crystallization conditions for the trypanosomal HPRT and preliminary analysis of X-ray diffraction data to a resolution of 2 A is reported. These results represent significant progress toward a structure-based approach to the design of inhibitors of the HPRT of trypanosomes with the long-range goal of developing new drugs for the treatment of Chagas' disease.

Animals↗
PubMed1997

[Viridans streptococci isolated from cerebrospinal fluid. Clinical significance of 9 cases].

Viridans streptococci (VS) are often isolated from cerebrospinal fluid (CSF). However, the significance of such isolates is poorly understood. In the present study we carry out a retrospective analysis of 9 patients in whom VS were isolated from CSF during a 1-year period at La Paz Hospital. Two patients (22.2%) had meningitis diagnosed through clinical, laboratory and bacteriologic findings. Both patients had predisposition diseases (previous difficult spinal tap, ventriculo-peritoneal shunt). The other isolations were considered as contaminants. Three patients (33.3%) with no VS meningitis had other different serious disease (sepsis without bacteriologic confirmation). VS are isolated with relative frequency from CSF, although they cause meningitis in less than one-quarter of the cases (those who have a predisposition disease). In the other cases, VS are isolated as contaminants of CSF and other disease should be search as cause of patient symptoms.

Adolescent↗
PubMed1995

Effects of urinary macromolecules on the nucleation of calcium oxalate in idiopathic stone formers and healthy controls.

Urinary macromolecules have attracted great interest because of their possible role as both promoters and inhibitors of calcium oxalate (CaOx) crystallization and it remains unclear whether there is any difference, in their nucleating activity, between stone formers and controls. We selected 9 male idiopathic CaOx stone formers whose 24-h urines presented no evidence of common urinary stone risk factors such as hypercalciuria, hyperoxaluria, hyperuricosuria, hypocitraturia, hypomagnesiuria or low glycosaminoglycans excretion and 12 male controls (matched for age and body weight) whose 24-h urines did not differ from those of stone formers. The study of urinary CaOx nucleation was made in freshly voided overnight urines whose biochemical composition was almost identical in the two groups. In filtered (0.22 micron) and ultrafiltered (10 kDa) urine we performed an oxalate tolerance test to determine the permissible increment of oxalate, the oxalate level for nucleation and the permissible increment of CaOx relative supersaturation (CaOx RS). In filtered urine from stone formers the permissible increment of oxalate was lower than controls (30 +/- 10.2 vs. 46.7 +/- 9.7 mg/l, P = 0.001), the oxalate level for nucleation was lower (64.4 +/- 14.2 vs. 79.5 +/- 15.6 mg/l, P = 0.035) and the permissible increment of CaOx RS was also lower (9.71 +/- 2.59 vs. 13.39 +/- 3.62, P = 0.018). In ultrafiltered urine these differences disappeared because the removal of macromolecules in stone formers significantly enhanced the oxalate-tolerance values. The difference between the change of the oxalate permissible increment of filtered and ultrafiltered urine allowed a distinction to be made between stone formers and controls that was not feasible in other ways (7.6 +/- 5.3 vs. 3.3 +/- 5.9 mg/l, P < 0.0001). The study suggests that, in idiopathic CaOx stone formers free from common urinary risk factors of CaOx crystallization, there is an increased tendency for CaOx nucleation in urine, which is mediated by macromolecular components.

Adult↗
PubMed1995

Stress radiography in the diagnosis of anterior cruciate ligament deficiency.

A prospective study was carried out to test the sensitivity and specificity of stress radiography in detecting anterior cruciate ligament deficiency in both knees of 116 patients using the Telos device. In 47 of these a total or partial rupture of the anterior cruciate ligament was diagnosed by arthroscopy, while the ligament was intact in the remaining 69 patients. The mean difference in radiological translation between the injured and the normal knee was greater than 5 mm (p < 0.001) in those with anterior cruciate deficiency, and less than 3 mm in the others. A differential displacement of up to 3 mm was considered normal. The sensitivity of the method was less than 67% and the specificity was 100%. Clinical diagnosis had a sensitivity of 70.2% and a specificity of 98.5%. Our findings suggest that, although a differential translation of more than 3 mm can be diagnostic, smaller differences do not rule out anterior cruciate deficiency.

Anterior Cruciate Ligament↗
PubMed1995

Seroprevalence of toxocariasis in children and a case of VLM.

An epidemiological study on toxocariasis in children was carried out at our hospital (Madrid, Spain) in relation with a case of toxocariasis in a child with chronic hypereosinophilia. The study was based on a positive result of the ELISA test, using excretory-secretory antigen from Toxocara canis. The seroprevalence in children was 1%.

Animals↗