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Biomedical subjects

C Calvo

Publications and source records attributed to C Calvo.

At least 73 records · Page 4Linked to original sources
PubMed1993

Decreased activation of lecithin:cholesterol acyltransferase by glycated apolipoprotein A-I.

Non-enzymatic glycation of plasma proteins may contribute to the excess risk of developing atherosclerosis in patients with diabetes mellitus. Glycated apolipoprotein A-I isolated from diabetic subjects was tested in vitro for its ability to activate lecithin:cholesterol acyltransferase, the principal cholesterol-esterifying enzyme in plasma. Activation by glycated apolipoprotein A-I was significantly lower at all concentrations than the activation by normal apolipoprotein A-I. Linear regression analysis of the kinetic data shows that the ratio app Vmax/app Km was significantly lower (p < 0.01) for glycated apolipoprotein A-I (0.29 nmol.l/h.mumol) than for normal apolipoprotein A-I (0.78 nmol.l/h.mumol). Because lecithin:cholesterol acyltransferase provides a driving force in reverse cholesterol transport by esterifying the cellular cholesterol removed by HDL, it is tempting to postulate that this abnormal activation may be associated with a reduction in reverse cholesterol transport and associated with the accelerated development of atherosclerosis in diabetic patients.

Apolipoproteins A↗
PubMed1992

Association in vivo of glycated apolipoprotein A-I with high density lipoproteins.

In diabetic patients, hyperglycaemia results in the non-enzymatic glycation of apolipoprotein A-I, the major protein of human high density lipoproteins. The effect of the non-enzymatic glycation on the association of apolipoprotein A-I with high density lipoprotein in vivo has been studied in the rat. The distribution volume obtained after injection of glycated apolipoprotein A-I was 2- to 3-fold higher in kidneys and approximately 30% lower in adrenals and ovaries than that obtained with apolipoprotein A-I. Analysis by gel chromatography of serum from donor rats shows that glycation diminishes the interaction between apolipoprotein A-I and high density lipoprotein. The findings in this study suggest that non-enzymatic glycation of apolipoprotein A-I may contribute to the development of atherosclerosis in patients with diabetes mellitus.

Adrenal Glands↗
PubMed1992

[Persistent microalbuminuria in insulin-dependent diabetics and cardiovascular risk factors].

A possible association of cardiovascular risk factors and early diabetic nephropathy was investigated in 32 patients. Microalbuminuria (radioimmunoassay), total and HDL cholesterol and triglycerides (enzymatic methods), glycosylated hemoglobin (colorimetric methods), Apo A1 and B (immunonephelometric) and LDL were measured. Microalbuminuria was present in 28% of patients. Compared to subjects with no microalbuminuria they had increased levels of cholesterol (200.2 +/- 13.5 (SE) vs 168.6 +/- 9.4 mg/dl, p < 0.025) and LDL cholesterol (171.9 +/- 14.1 vs 137.4 +/- 9.1 mg/dl, p < 0.025). Systolic blood pressure was also higher in patients with microalbuminuria (127.8 +/- 3.9 vs 114.5 +/- 2.8 mmHg, p < 0.01). Microalbuminuria was correlated to the level of diastolic blood pressure (r = 0.74, p < 0.025). Thus, persistent microalbuminuria in insulin dependent diabetic patients is associated to cardiovascular risk factors which may explain the increased cardiovascular morbidity and mortality in these patients.

Adolescent↗
PubMed1992

[The 2-chambered right ventricle with an anomalous muscle bundle].

The clinical picture, course, electrocardiogram and chest X-Ray of 30 patients with the angiocardiographic diagnosis of double-chambered right ventricle, along with the echocardiogram in 18 and surgical results in 26 are analyzed. A ventricular septal defect was associated in most of the patients, that had spontaneous closure in some of them. The clinical picture and serial catheterization in some cases suggested progressive obstruction of the right ventricular outflow tract. In this, as in most of the reported series, the history, physical examination, ECG and roentgenogram were inconclusive for diagnosis of this entity. Two-dimensional echocardiography was the most reliable non invasive method to assess this malformation, even superior to catheterization in some aspects. The angiocardiographic findings are quite distinctive, allowing differentiation of other types of subpulmonary stenosis. In order to achieve a good surgical result is essential a precise diagnosis of this malformation and of the associated anomalies. The long-term prognosis was good as in most of the reported series.

Angiocardiography↗
PubMed1991

The use of the Dornier MPL-9000 lithotripter in the treatment of gallbladder and renal stones. Early experience.

The experience of two units (Gastroenterology and Urology) of Clínica La Luz, Madrid, in the treatment of gallbladder and renal lithiasis using the Dornier MPL-9000 lithotripter is reported herein. This lithotriptor has been utilized in the treatment of all cases of gallbladder calculi for which it is indicated and renal calculi localized high up (kidney), and in those cases that are difficult to treat with other lithotriptors such as patients with kyphoscoliosis, radiolucent calculi, elderly patients, children, etc.). During the first year the gallstone lithotripsy unit was utilized, 401 patients were referred for treatment. Of these, 180 met the criteria for patient selection. (Over 360 have been treated to date.) Sixty of these 180 patients had a single gallstone of up to 2.5 cm. These 60 patients were selected for the study since they comprised a group where the best results could be expected. The aim of studying this patient group was to evaluate the results achieved by lithotripsy and the short and medium-term outcome in this ideal group of patients. Concerning renal lithiasis, these are the first 100 cases treated with the MPL-9000 (currently over 420 have been treated). Eighty cases had a single calculus (60 caliceal and 20 pyelic), 15 had multiple calculi, and 5 had a staghorn stone. Treatment for gallbladder and renal lithiasis was exclusively by shock waves; i.e., as monotherapy with no other auxiliary procedure. The average number of shock waves used was 2,350 with a mean kV of 18 for gallbladder lithiasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Extracorporeal biliary lithotripsy: results in 60 cases of single calculus].

The outcome of 60 cases of single biliary stone with a maximum diameter of 25 mm was evaluated. The patients were symptomatic, with functioning gallbladder, and were selected from a group of 180 to evaluate the effects of electrohydraulically generated shockwaves on a priori ideal cases for this procedure. In seven patients fragmentation was not achieved, probably because of the pigmentary character of the stone, that was later verified at cholecystectomy. In 20 out of the 53 in whom fragmentation was satisfactory (38%), fragments were not observed after 24 hours. 32 patients (54%) had a stone-free gallbladder 3 months afterwards; at six months, the number had increased to 40 (66%). This rate becomes 77% if only the cases with fragmentation are considered. In 29% of patients episodes of colicky biliary pain developed as complication. No case of pancreatitis or stuck in gallstone were observed. We conclude that shock waves appear as an excellent therapeutic alternative in single gallstones up to 25 mm in size.

Adult↗
PubMed1990

Time trend of PCB concentrations in surface sediments from a hypertrophic, macroalgae populated area of the lagoon of Venice.

The concentrations of polychlorinated biphenyls have been determined over a period of 1 year in surface sediments sampled monthly and semi-monthly in the lagoon of Venice. At the sampling station, due to the poor water circulation and an over-abundance of nutrients, macroalgae thrive in spring-summer and standing crops greater than 12 kg m-2 were determined. As a consequence of rapid algal decomposition, sediment PCB concentrations were observed to increase. In particular, on occasions when anoxia occurred at the end of July and all the biomass had decayed, PCB concentrations increased by more than one order of magnitude. In March, when macroalgae started to grow, concentrations were 13 ng g-1 (dry wt); in July-August they exceeded 100 ng g-1. The sediment PCB concentrations were restored to the previous values after algal biomass became negligible, in November. Concentrations of PCBs in young algae fronds were 27 +/- 12 ng g-1, and 121 +/- 4 ng g-1 in older fronds.

Eukaryota↗
PubMed1990

Precipitation of struvite in urine medium by urease-positive and urease-negative Yersinia strains.

Yersinia strains either urease-positive or urease-negative were examined for precipitation of struvite in human urine at 25 and 37 degrees C. All urease-positive strains and 8 out of 10 urease-negative strains showed the ability to produce these crystals. Incubation time required for precipitation was longer for urease-negative strains and quantity of struvite formed was higher in urease-positive ones. Regarding incubation temperature, no significant influence has been observed.

Humans↗
PubMed1989

[Food poisoning by scombroid fish (tuna) in a communal dining room of a company].

We report a collective tuna fish poisoning which developed on June 10, 1988, in a staff dining room in Castellón. Twenty-one people were involved (attack rate 42.9%). The major symptoms were diarrhea, abdominal pain, headache, facial flushing and oral burning. The mean duration of the symptoms was 15 hours. The ingestion of tuna fish was significantly associated with the illness (p less than 0.001) when the other foodstuffs were controlled. Tuna fish had been defrosted at room air temperature during 14 hours. The analysis of several foodstuffs (there were no tuna fish remains available) and the food handling staff did not disclose pathogens. We discuss the etiology, pathogenesis, epidemiology and control of this type of food poisoning.

Animals↗
PubMed1989

Struvite crystal precipitation by different phenotypes of Yersinia.

Extracellular formation of struvite crystals by Yersinia enterocolitica, Y. frederiksenii, Y. kristensenii and Y intermedia strains was investigated. Precipitation of crystalline structures was found with 19 of the 187 strains tested, its formation being more frequently observed at 25 degrees C than at 37 degrees C. Production of struvite was greater in Y. enterocolitica strains belonging to biotype 1, serogroup 0:7,8 and lysotype Xz, than observed in other phenotypes. Quantitative assay in a liquid medium showed that struvite formation began after 3 d of incubation; production of these crystals increased up to 15 d. Crystalline structures were examined using electron microscopy and their extracellular formation was observed.

Crystallization↗
PubMed1989

[Comparative prospective randomized multicenter study of 2 dosage protocols of nitrendipine in patients with mild to moderate hypertension].

134 patients with mild to moderate hypertension received nitrendipine during 6 months in an increasing fashion. Therapeutic goal was achieved in 92% of the patients (DBP less than 95 mmHg) in which BP decreased from 168.4 +/- 13.7/105.0 +/- 1.1 to 140.9 +/- 12.7/84.4 +/- 6.6 (p less than 0.001). In patients whose BP was not controlled with a single initial doses of 20 mg/day, the degree of control was similar with 40 mg single dose and 20 mg twice a day. The most frequently encountered undesirable effects were those caused by the vasodilator action of the drug. No changes in blood glucose and plasma lipid levels were found.

Adult↗
PubMed1988

Non enzymatic glycation of apolipoprotein A-I. Effects on its self-association and lipid binding properties.

In diabetic patients, hyperglycaemia results in the non enzymatic glycation of many proteins including apolipoprotein A-I. We purified glycated apo A-I and compared its lipid binding properties to those of normal apo A-I. Analysis of tryptophan fluorescence spectra and of fluorescence quenching in the presence of iodine showed that glycation of apo A-I induces a decrease in the stability of the lipid-apoprotein interaction and in that of the apoprotein self-association. Repetitive ultracentrifugations of High Density Lipoprotein (HDL) samples containing radioiodinated apo A-I or glycated apo A-I revealed that glycation of the apoprotein facilitates its dissociation from HDL. These results suggest that the non enzymatic glycation of apo A-I may affect the structural cohesion of HDL particles.

Algorithms↗
PubMed1987

[Idiopathic perforation of the choledocus in childhood].

The purpose of this report is to describe a seven-years-old patient with an idiopathic perforation of the common bile duct. This disorder is more frequent in the first weeks of life, and the clinical features are not well known. Properly treated, the majority of infants survive without sequelae. Furthermore, a review of the literature is made.

Child↗
PubMed1986

Antagonism between Yersinia intermedia and Yersinia enterocolitica in water.

One strain of Yersinia enterocolitica and one strain of Y. intermedia were grown in peptone water at 25 or 37 degrees C, or in ground water at 15 degrees C. Similar growth rates were observed when these strains were cultivated separately in the same media and at the same temperature. Mixed cultures at 37 degrees C displayed equivalent growth rates. In contrast, mixed cultures incubated at 15 or 25 degrees C were regularly unfavourable to Y. enterocolitica, whereas they did not modify the growth of Y. intermedia. A bacteriophage active on Y. enterocolitica and not on Y. intermedia was characterized from the filtrate of mixed cultures at low temperatures. This phage produced by the lysogenic Y. intermedia strain might be a potential factor responsible for the inhibition of Y. enterocolitica, since no additional antibacterial factor or nutritional competition between Y. intermedia and Y. enterocolitica were found in the mixed cultures.

Antibiosis↗
PubMed1986

Production of bacteriocin-like substances by Yersinia frederiksenii, Y. kristensenii, and Y. intermedia strains.

The production of bacteriocin-like substances by strains of Yersinia frederiksenii, Y. kristensenii and Y. intermedia in broth culture was established. These substances showed a selective activity against Y. enterocolitica, Y. frederiksenii, Y. kristensenii and Y. intermedia strains. Electron micrographs revealed the presence of phage tails in culture media. The production of these substances was detected in cultures grown at 25 degrees C but not in those grown at 37 degrees C, while these bacteriocin-like substances were active at 25 and 37 degrees C. Y. enterocolitica serogroups 0:3 and 0:9 were more susceptible to these bacterin-like substances than strains of Yersinia isolated from environmental sources.

Bacteriocins↗