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Biomedical subjects

M Calvo

Publications and source records attributed to M Calvo.

16 recordsLinked to original sources
PubMed1992

Effect of beta-lactoglobulin on the activity of pregastric lipase. A possible role for this protein in ruminant milk.

The interaction of bovine beta-lactoglobulin with palmitic and oleic acids has been studied by a partition equilibrium method. Bovine beta-lactoglobulin displays only one high affinity binding site for fatty acids whose association constants for palmitic and oleic acids are 4.2 x 10(6) and 2.3 x 10(6) M-1, respectively. However, other binding sites with low affinity are also present. The existence of one high affinity binding site is in accordance with the amount of fatty acids naturally bound to beta-lactoglobulin isolated from milk. The effect of beta-lactoglobulin on ruminant pregastric lipases from a pharyngeal extract has been assayed. The activity of pharyngeal lipase on a triglyceride emulsion is increased about 200%, 250% and 190% in the presence of 10 mg/ml, 20 mg/ml and 40 mg/ml of beta-lactoglobulin, respectively, the last concentration representing that found physiologically in colostrum. Albumin, another ligand-binding protein, increases the activity of this enzyme to a lesser extent and high levels tend to inhibit enzyme action. These results indicate that beta-lactoglobulin could participate in the digestion of milk lipids during the neonatal period by enhancing the activity of pregastric lipase through removal of the fatty acids that inhibit this enzyme.

Animals↗
PubMed1992

Expression of mRNAs for alpha-fetoprotein (AFP) and albumin and incorporation of AFP and docosahexaenoic acid in baboon fetuses.

alpha-Fetoprotein and albumin, two members of a multigene family, reversibly bind fatty acids with high affinity. The origin of alpha-fetoprotein (AFP) and albumin present in fetal tissues other than the liver and yolk sac is a subject of controversy. In this work, we have searched for the presence of the albumin and AFP mRNA molecules in different fetal organs of the baboon (Papio cinocephalus), using a highly sensitive gel-blot hybridization assay with human albumin and AFP cDNA probes. Large amounts of albumin and AFP mRNA molecules were found in the fetal liver; significant quantities were also present in the gastrointestinal tract and in the kidney. No detectable levels were found in the other tissues examined (brain, skin, spleen, pancreas, muscle, heart, thymus, placenta, and amnion). After injection of radiolabeled AFP into pregnant baboons, all fetal tissues took up the protein. White adipose tissue, kidney, intestine, lung, liver, and cerebral cortex showed a great uptake of exogenous AFP. [14C]Docosahexaenoic acid (22:6, n-3), injected at the same time, was actively transferred from the maternal compartment across the placenta and incorporated into cellular lipids by all fetal tissues and particularly by liver (around 70% of total incorporation). The levels of [14C]docosahexaenoic acid per gram of tissue increased in the order: maternal blood less than placenta less than fetal liver, indicating a selective accumulation of this fatty acid by the fetus. These results indicate that intracellular AFP in non-hepatic tissues of the developing baboon is, for the most part, of plasma origin.

Albumins↗
PubMed1992

Synthesis of lactoferrin and transport of transferrin in the lactating mammary gland of sheep.

Two iron-binding proteins, lactoferrin and transferrin, are present in ruminant milk. Lactoferrin commonly has been assumed to be a product of mammary synthesis, but the origin of milk transferrin has not been elucidated. The objective of this experiment was to study the synthesis and distribution of these two proteins in the mammary gland of sheep. Explants from lactating mammary gland of sheep have been cultured in the presence of [3H]leucine to determine rates of synthesis of lactoferrin and transferrin. After incubation, [3H]lactoferrin was found, but labeled transferrin was not. The capacity of the mammary gland to synthesize lactoferrin decreased markedly in the first 24 h of lactation. Immunohistochemical techniques were utilized to identify the locations of lactoferrin and transferrin in the mammary gland. Transferrin was found in the colostrum contained in the alveolar lumen, in the cytoplasm of the secretory cells, and in the connective tissue between the mammary acini. High concentration of transferrin was found in the basal membrane of the secretory alveolar cells, mainly in those near capillary vessels. Lactoferrin was found in the colostrum and in the cytoplasm of secretory cells with a more homogeneous distribution than transferrin. The connective tissue stained negative for lactoferrin. These results suggest that, although lactoferrin is synthesized by mammary gland of the sheep, transferrin comes from blood serum, probably by a receptor-mediated mechanism of transcytosis.

Animals↗
PubMed1991

Cuban programme for prevention of sickle cell disease.

The percentage of carriers of the sickle cell gene in Cuba ranges from 3 to 7% in different regions. In 1983 the National Medical Genetics Centre initiated a programme for the control of sickle cell disease, which was started in Havana and later extended nationwide. The programme is based on mass education, screening and supportive genetic counselling, care of affected individuals, and availability of prenatal diagnosis. 806,935 pregnant women had been screened by the end of 1989: 29,913 (3.7%) were heterozygous, homozygous or doubly heterozygous for abnormal haemoglobin. 19,686 fathers (67%) were also tested: 1268 at-risk couples were detected. 531 elected to have prenatal diagnosis; 404 results were obtained and 98 affected fetuses (SS or SC) found. In 72 cases the pregnancy was terminated.

Anemia, Sickle Cell↗
PubMed1991

Case report 674: Well-differentiated lymphocytic lymphoma with skeletal involvement.

We report the case of a man with generalized osteosclerosis secondary to well-differentiated lymphocytic lymphoma. This finding is considered to be exceptional in this type of lymphoma, especially when other organs were not found to be involved. A year after the diagnosis was established the patient appeared to be in relatively good health. The radiological pattern showed no change from the original studies, nor was there any evidence of neoplastic involvement in any other location.

Aged↗
PubMed1991

Insulin in bovine colostrum and milk: evolution throughout lactation and binding to caseins.

The changes in insulin concentration in bovine milk in the first period of lactation and its association with other milk proteins were studied. Highest concentration was found in the first milking (327 ng/ml). This concentration fell within the first 24 h postpartum to about 50% of its initial value. By d 3, the level was about 25%, and, on d 7, a stable concentration was reached at approximately 46 ng/ml (about 14% of its initial value). This concentration is about 100 times higher than that in serum, which suggests a specific mechanism of transfer from blood to milk. Colostral whey obtained by ultrafiltration or ultracentrifugation contains much less insulin than colostrum. When colostrum or milk was incubated with [125I]insulin and whey and casein fractions were separated by precipitation, it was observed that most insulin remained with the casein. However, when colostrum was incubated with [125I]insulin and subjected to gel filtration, most of the radioactivity corresponded to free insulin, indicating that insulin is associated with the precipitated casein but not with the casein micelles in solution.

Animals↗
PubMed1991

[Birth spacing: collaborative study of eight state maternities].

We collected data con 2,434 deliveries of live newborns (1.5% of the total for the country) in 8 state supported maternity wards of urban areas in Chile. First children, stillbirths and twins were excluded. Proportion of the sample according to city was: West Santiago 41%, Talcahuano 16%, Valparaíso 14%, Arica 8%, Chillan 7%, Valdivia 6%, Punta Arenas 6%, and Coyhaique 2%. The intergenesic interval was over 5 years in 38%, over 4 years in 48% and under 1 year in only 1.9% of cases, with minimal inter-city variation. Contraceptive agents were used by 26% of mothers with intergenesic interval under 1 year and 21% of those over 5 years, significantly higher than that found in the other intervals. Maternal age was between 20 and 29 years in 60%; only 8% of mothers were younger than 20 or older than 40 years of age. The incidence of cesarean section increased from 21 to 28.6% with increasing intergenesic interval. Mean weight of newborns was 3,338 g, significantly lower in the intergenesic interval under 1 year (3,251 g). The incidence of low birth weight was also highest in the latter group.

Adult↗
PubMed1991

[A study of arteriosclerotic disease and of ischemic cardiopathy in particular and the associated risk factors in the Autonomous Basque Community. The Euzkadi project].

The aim of the Euzkadi Project was to know the prevalence rate of cardiovascular disease and the high risk factors (hypertension, hypercholesterolemia and cigarette smoking) in the Basque Country to carry out an intervention trials to reduce these factors if we have collaboration of the Public Health Service. We have studied a sample of 4,800 men, 25-64 years old, randomly selected (1,600 men in each province), the examination was done by cardiologist using the cardiovascular questionnaire by Blackburn and Rose, the cholesterol was tested in WHO Collaborating Lipid Reference Center (Prague) and the electrocardiogram was studied by Minnesota Code. The rate of Atherosclerotic disease was 69%, coronary heart disease 49% (12% angina típica, 9% angina atípica and 28% myocardial infarction), stroke 7%, and peripheral vascular disease 13%. The rate of silent myocardial infarction was 31%. The rate of hypertension was 24%, hypercholesterolemia 14% and cigarette smoking 40%.

Adult↗
PubMed1990

Meniscal repair following meniscectomy: mechanism and protective effect. Experimental study in the dog.

Meniscal repair was studied to evaluate the mechanism and its potential protective effects on the articular cartilage in an experimental model consisting of 68 knees of adult dogs on which five different types of medial meniscectomy were performed. The results were assessed by macroscopic, microangiographic, and histological methods, after a sequential follow-up period of 10-450 days. Two different mechanisms of meniscal repair were observed, depending on whether meniscal section had been performed in vascular (total meniscectomy) or avascular (subtotal or partial meniscectomy) zones. It was also observed that the repaired meniscal tissue does not prevent articular cartilage degeneration. This is more closely related to the size of the meniscal fragment preserved at meniscectomy. Due to the biomechanical importance of the meniscus and the lack of functional relevance of the repaired meniscal tissue, the most conservative approach possible to meniscectomy is recommended.

Animals↗
PubMed1979

[Nephrotic syndrome by diffuse mesangial sclerosis (author's transl)].

This case deals with a 15-month old male child affected with a nephrotic syndrome resulting in grave chronic renal failure, determined histologically as diffuse mesangial sclerosis. The most frequent causes of nephrotic syndrome in the first year of life are analyzed along wiht their diagnostic differential, with special attention to the Finish or microcystic congenital nephrotic syndrome and to diffuse mesangial sclerosis. In the discussion contradictions existing in the bibliography on diffuse mesangial sclerosis are shown in its clinical and developmental aspects as well as the prognostic and even in the pathological anatomy, which leads us to believe that this illness may be more complex than what it appears, and subdividing it into illnesses of different etiology, development and prognosis; or that some of the cases. described as such may not be the same as those described by R. Habib in 1973. In the present case the deposits of C3 and IgM are worth noting, as they were not described in the other 11 cases, also the study done with the electron microscope, which also was not done in the previous cases.

Complement C3↗
PubMed1979

Septic shock in pediatrics.

A review of the septic shock syndrome in pediatrics, analyzing its actual incidence in clinical practice, etiopathological factors, physiopathology, clinical manifestations in the different stages of the disease, diagnostic criteria, prognostic, and treatment is presented.

Acute Kidney Injury↗
PubMedDate not supplied

Specific interactions of synthetic peptides derived from P. falciparum merozoite proteins with human red blood cells.

In the search for strategies which might help in the elucidation of molecular mechanisms involved in the red blood cell (RBC) invasion by P. falciparum merozoites, and with the specific aim of establishing whether synthetic peptides derived from selected parasite proteins bind to human RBCs, 26 different peptides were chemically synthesized and radiolabeled. It was found that the peptides could be grouped, according to their RBC-binding kinetics, into high, medium and low binding activity. A correlation was detected between the high binding activity of a peptide and the presence of either a KEK motif (or its variants LEK or KEL) or a NVXAA (where X is V or Y). Peptides with medium or low binding activities did not possess either of these two consensus sequences. Selective modification of amino acids within the KEK motif diminished their uptake or binding capacity. Competitive inhibition assays of labeled or unlabeled peptide demonstrated a correlation between the presence of KEK or NVXAA motifs and a high binding activity of a peptide. Invasion-inhibition studies showed a direct correlation between a peptide's binding activity and inhibitions of human RBC reinvasion. Other experiments showed that high binding activity peptides show a decreased uptake with related and nonrelated human erythrocytes.

Amino Acid Sequence↗
PubMedDate not supplied

[Bone lithiasis].

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Kidney Calculi↗