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Biomedical subjects

C Segura

Publications and source records attributed to C Segura.

At least 37 records · Page 2Linked to original sources
PubMed1997

Vitamin D receptor gene expression in human pituitary gland.

1,25-dihydroxyvitamin D3 has important physiological effects such as calcium transport and cell growth and differentiation. These biological effects are mediated by their binding to specific intracellular receptor termed vitamin D receptor (VDR). VDR mRNA expression has been demonstrated in several tissues, but to date, there is no information about its presence in the human pituitary gland. In this report, we demonstrate VDR mRNA expression using the reverse transcription-polymerase chain reaction (RT-PCR), as well as the cellular expression of VDR by immunohistochemistry, both in the human pituitary gland. These results suggest the possibility that, like in the rat pituitary, VDR may regulate the human pituitary gene expression and hormone secretion.

Adult↗
PubMed1997

Beta-lactamases of Mycobacterium tuberculosis and Mycobacterium kansasii.

Re-emergence of infectious diseases caused by mycobacteria as well as the emergence of multiresistant strains of Mycobacterium has promoted the research on the use of beta-lactames in the treatment of such diseases. Mycobacteria produce beta-lactamases: M. tuberculosis produces a wide-spectrum beta-lactamase whose behaviour mimicks those of Gram-negative bacteria. M. kansasii produces also beta-lactamase which can be inhibited by clavulanic acid. An overview on beta-lactamases from both species is reported.

Antitubercular Agents↗
PubMed1996

Identification of Plasmodium falciparum MSP-1 peptides able to bind to human red blood cells.

To determine amino acid sequences of the Plasmodium falciparum MSP-1 protein that interact with red blood cell membranes in a specific receptor-ligand interaction, 78 sequential peptides, 20 amino acids long and spanning the entire length of the molecule, were synthesized and analysed with a specific binding assay developed for this purpose. Results show that peptides based on conserved and dimorphic regions of MSP-1, interact with human red blood cells (RBCs). This interaction occurs predominantly with peptides contained within the MSP-1 proteolytic fragments of 83 kDa, 38 kDa, 33 kDa and 19 kDa. Affinity constants of these peptides were between 140 and 250 nM. Peptide-RBC binding post enzyme treatment showed that the RBC receptors are not sialic acid dependent and appear to be proteic in nature. Some of these peptides inhibited merozoite invasion of RBCs yet did not inhibit intraerthrocytic development. These peptides, in conjunction with those from other merozoite surface proteins, may be used to rationally design a second generation of synthetic peptide-based malaria vaccines.

Amino Acid Sequence↗
PubMed1996

Quality of life and medicine: a historical note.

This paper analyses the historical origins of the concepts of welfare as a positive right and of quality of life. The latter has historical antecedents but has become important in the latter half of the twentieth century, owing to the conflict between consumer demands for medicine and constraints upon spending. It is argued that, beyond the immediate economic and utilitarian contexts, the concept of quality of life has the potential to promote individual liberty and a more subjectively-based approach to medicine.

History, 20th Century↗
PubMed1996

[Clostridium difficile and diarrhea associated with the use of antibiotics in the origin of nosocomial and community-acquired diarrhea].

BACKGROUND: Clostridium difficile is currently recognized as an important nosocomial enteric pathogen. The significance as etiologic agent of community and nosocomial diarrhea is not well known in Spain. METHODS: Retrospective study of all cases of community diarrhea that required admission in the hospital and all nosocomial diarrhea observed in a period of three months in a 450-bed university hospital. We performed conventional coprocultives and detection of toxin-A of C. difficile with the method ELISA Premier. RESULTS: During the period of study were included 66 patients, 19 pediatrics and 47 adults patients (23 males, 24 females, age: 54.5 +/- 21.8 years). Three cases (15.8%) of pediatrics patients were diagnosticated of antibiotic-associated diarrhea, only one case were of nosocomial origin. Toxin A of C. difficile were detected in 6 cases, all were patients under two years old, represented 60% of these patients. The origin of diarrhea were: community in 32 cases and nosocomial in 15 of adults patients, in 18 cases (38.3%) were diagnosticated antibiotic-associated diarrhea, 11 were nosocomial. Toxin A of C. difficile were detected in 12 patients, 25.5% of adults, and 4 cases had criteria of C. difficile associated diarrhea, representing 8.5% of the diarrhea. None of this cases were suspected during admission. CONCLUSIONS: Antibiotic-associated diarrhea and C. difficile associated diarrhea were not infrequent cause of diarrhea of nosocomial and of community origin in our environment. We recommended culture and/or detection of toxins of C. difficile in patients who were treated with antibiotics and diarrhea of more than 72 hours of evolution.

Adolescent↗
PubMed1995

Beta-lactamase activity in mycobacteria other than M. tuberculosis.

Beta-lactamase activity was studied in 142 non-tuberculosis mycobacterial strains. The distribution according to species was as follows: four M. avium, 14 M. chelonae, 10 M. fortuitum, 59 M. gordonae, 55 M. kansasii. The spectrum of hydrolysis of the beta-lactamases was screened using an acidimetric method and the characterization was performed by analytical isoelectric focusing.

Bacterial Proteins↗
PubMed1992

In human malaria protective antibodies are directed mainly against the Lys-Glu ion pair within the Lys-Glu-Lys motif of the synthetic vaccine SPf 66.

The KEK (Lysine-Glutamic acid-Lysine) motif is frequently found in the primary structure of certain malaria proteins involved in invasion, and plays an important role in the interaction of these proteins with the erythrocyte. This motif is contained in a peptide which forms part of the polymeric synthetic malaria vaccine SPf 66, currently undergoing extensive human trials. Analysis of the antibody titres against the subunit peptides that comprise this vaccine has shown that protection is associated with high titres to the KEK-containing peptide. In this paper we examine the fine recognition of this motif by polyclonal sera from protected vaccinated individuals, demonstrating the critical role played by the interacting ion pair formed between the amino terminal lysine (K) and glutamic acid (E), which act as contact residues for an important proportion of the antibody population directed against this vaccine. This ion pair in the KEK motif constitutes perhaps one of the most important malaria epitopes involved in protection, and could explain the mechanism through which protective immunity is acquired.

Amino Acid Sequence↗
PubMed1992

[Combined use of real-time digital subtraction radioscopy and computerized tomography: potential advantages in diagnostic and interventional radiology].

The idea of combining fluoroscopy and CT arose from the daily practice in diagnostic and interventional radiology. A Diasonics OEC high-performance image intensifier complete with a digital subtraction system was connected to a Siemens Somatom-DRH CT scanner to work in tandem. CT is used for a localization in-depth and fluoroscopy for the subsequent maneuvers within an organ or body compartment. With this combination, complex procedures such as transarterial portography, percutaneous embolizations, pain treatment and manipulation for catheterization of the bile ducts and urinary tract could be performed in one place and in one session. CTF is especially useful when patients should not be moved about from room to room or undergo an examination in several sessions, as it happens with children or critically ill or contagious patients.

Adult↗
PubMed1991

Staging of hepatocellular carcinoma by ultrasonography, computed tomography, and angiography: the role of CT combined with arterial portography.

A series of 60 patients with hepatocellular carcinoma (HCC) were evaluated over a 2-year period of ultrasonography (US), computed tomography (CT), and angiography. The angiographic studies carried out with intraarterial digital technology were compared to both US and CT of the liver. In 16 of 60 patients, we observed discordance of the findings obtained with angiography, CT, and US. We therefore compared these three methodologies in those cases where diagnostic discordance was noted. In our experience, US had a sensitivity of 73.4%, 76.7% for CT, and 95% for angiography. In 13 of 60 patients, we performed CT with arterial portography (CTAP) which demonstrated a better resolution than conventional CT. In view of the sensitivity of US - comparable to that of CT - and for the even greater sensitivity of intraarterial digital angiography, we performed an US study of patients at risk of HCC. CT was found to play a diagnostic/staging role after angiographic study has been performed, especially when enhanced by arterial portography.

Adult↗
PubMed1989

Activity of amoxycillin/clavulanate against beta-lactamase-producing Escherichia coli and Klebsiella spp.

We studied the susceptibility to the amoxycillin/clavulanate combination (2:1), and the characteristics of the beta-lactamases, of 1410 amoxycillin-resistant strains of Enterobacteriaceae (785 of Escherichia coli and 625 of Klebsiella spp.). Of the E. coli strains, 97.07% were susceptible to the combination and 98.85% produced plasmid-mediated beta-lactamases. Of the Klebsiella spp. strains, 87.84% were susceptible to the combination and 75.36% produced plasmid-mediated beta-lactamases. In both cases, the differences in MIC values, according to the characteristics of the beta-lactamases of the strains, were statistically significant. Of the 99 strains of E. coli and Klebsiella spp. that were not inhibited by amoxycillin 16 mg/l with clavulanate 8 mg/l, 19 hyperproduced chromosomal beta-lactamase; five produced a plasmid-type beta-lactamase as well. Fifty-seven strains produced two plasmid-type beta-lactamases.

Amoxicillin↗
PubMed1989

[Echography and scintigraphy using technetium 99m pyrophosphate in the diagnosis of cardiac amyloidosis].

The diagnosis of amyloid cardiomyopathy was only based, until the last few years, on the results of invasive techniques. It seems presently that the combined contribution of cardiac sonography and scintigraphy using technetium 99m pyrophosphate, makes, most of the time, this diagnosis possible without need for additional examinations. This notion is illustrated by a typical case-report and data from the literature. Demonstration on the cardiac sonogram of a thickening of the walls-while the context and especially the electrocardiogram are not in favor of a left ventricular hypertrophy--associated with a very particular "hyperechoing" aspect and an abnormal fixation on the scintigram, may be considered specific of this disease.

Amyloidosis↗
PubMed1987

Valinomycin, a degranulating agent in rat mast cells which inhibits calcium-uptake.

The effect of valinomycin on both, mast cell histamine release and on calcium (45Ca)-uptake processes was examined. Pleural and peritoneal mast cells were purified in isotonic Percoll (pH = 7) and mixed populations were used in the experiments. Valinomycin (10(-9)-10(-5) M) stimulated histamine release in isolated rat mast cells when the incubation medium contained high K+ concentrations (Tris-K+ with 150 mM K+), but not in other media such as Tris-Na+ (120 mM Na+) or Tris-sucrose (300 mM sucrose). In contrast, in the absence of valinomycin, elevated K+ levels in the external environment did not activate mast cell secretion. Optimum response in valinomycin-treated mast cells was obtained when the cells were incubated for 60 min. Also valinomycin (10(-5) M) induced substantial inhibition of 45Ca-uptake while lower doses (10(-9)-10(-7) M) did not affect or only slightly increased uptake. In this paper valinomycin is shown to be a degranulating agent eliciting mediator release in mast cells incubated in the presence of high K+ levels, which does not require extracellular calcium and inhibits 45Ca uptake. The possibility that valinomycin acts as a K+ ionophore, as in other secretory systems, is discussed.

Animals↗
PubMed1986

Incidence of strains producing plasmid determined beta-lactamases among carbenicillin resistant Pseudomonas aeruginosa.

A total of 1056 strains of Pseudomonas aeruginosa isolated from human clinical specimens from patients was collected from eight laboratories in order to study the frequency of plasmid-determined beta-lactamase producers and the different enzymes represented. The strains from each laboratory comprised consecutive, non-repeated, clinical isolates. In the 166 strains selected because they were carbenicillin resistant, the isoelectric points of the beta-lactamases were studied by means of analytical isoelectric focusing and the different types of plasmid-determined beta-lactamases identified. Seventy-five of the strains (45.18%) were plasmid-mediated beta-lactamase producers; the frequency varied among laboratories from 0% to 100%. Overall the most frequently identified beta-lactamase type was PSE-1 (49.34%) followed by TEM-1 (37.34%). The remaining carbenicillin-resistant strains did not produce plasmid-determined beta-lactamases.

Carbenicillin↗