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Biomedical subjects

M Prieto

Publications and source records attributed to M Prieto.

At least 109 records · Page 6Linked to original sources
PubMed1995

Self-association of the polyene antibiotic nystatin in dipalmitoylphosphatidylcholine vesicles: a time-resolved fluorescence study.

The interaction between Nystatin and small unilamellar vesicles of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, both in gel (T = 21 degrees C) and in liquid-crystalline (T = 45 degrees C) phases, was studied by steady-state and time-resolved fluorescence measurements by taking advantage of the intrinsic tetraene fluorophore present in this antibiotic. It was shown that Nystatin aggregates in aqueous solution with a critical concentration of 3 microM. The enhancement in the fluorescence intensity of the antibiotic was applied to study the membrane binding of Nystatin, and it was shown that the antibiotic had an almost fivefold higher partition coefficient for the vesicles in a gel (P = (1.4 +/- 0.1) x 10(3)) than in a liquid-crystalline phase (P = (2.9 +/- 0.1) x 10(2)). Moreover, a time-resolved fluorescence study was used to examine Nystatin aggregation in the membrane. The emission decay kinetics of Nystatin was described by three and two exponentials in the lipid membrane at 21 degrees C and 45 degrees C, respectively. Nystatin mean fluorescence lifetime is concentration-dependent in gel phase lipids, increasing steeply from 11 to 33 ns at an antibiotic concentration of 5-6 microM, but the fluorescence decay parameters of Nystatin were unvarying with the antibiotic concentration in fluid lipids. These results provide evidence for the formation of strongly fluorescent antibiotic aggregates in gel-phase membrane, an interpretation that is at variance with a previous study. However, no antibiotic self-association was detected in a liquid-crystalline lipid bilayer within the antibiotic concentration range studied (0-14 microM).

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1995

Central hypoventilation syndrome associated with ganglioneuroblastoma.

In this paper the authors describe a case of central hyperventilation syndrome associated with a neural crest tumor. The girl had several apneic spells at the age of three years. She had a tracheostomy and mechanically assisted ventilation while asleep. Routine hematologic studies and chest x-ray were within normal limits. Computerized tomography scan and magnetic resonance imaging revealed a left paraspinal mass suggestive of a neural crest tumor. This mass was excised and histopathologic findings of this tumor revealed a ganglioneuroblastoma.

Child, Preschool↗
PubMed1995

Numerical characterization study of Micrococcaceae associated with lamb spoilage.

A computer-assisted characterization of 296 Micrococcaceae isolates obtained from aerobically chill-stored lamb carcasses was carried out using a probability matrix and Bayesian identification theorems, complemented with cluster analysis. Preliminary identification was done with an original probability matrix comprising 37 previously described taxa and 32 tests. Although its statistical quality was adequate, the percentage of identification of field strains to species level was only 70% (96.6% identified with genera). To achieve an improved characterization, cluster analysis was subsequently performed on this group and an additional 26% could be associated with defined species, with five more taxa defined. The combined use of both approaches was judged positive as new identifications and better discrimination could be achieved. The majority of our isolates belonged to the Staphylococcus species group. Many species and groups of staphylococci increased as the spoilage progressed.

Animals↗
PubMed1995

Somatosensory evoked potential elicited by acupoint's stimulus.

Based on the observation that repeated acupoint stimulation elicits evoked potentials whose latency varies as a result of the stimulus intensity we assessed the evoked potential elicited by stimulus of three acupoints (Hegu, Shenmen and Houxi), comparing the results to the potentials produced by median nerve stimulus and nonacupunctural point. Fourteen healthy individuals were studied, and no modifications related to the Hegu and Shenmen point potentials increased with the amount of stimuli, until it reached a plateau at around 400 stimuli. It did not vary for Houxi and the nonacupunctural point. We conclude that the somesthesic afference from acupunctural points must involve control circuits that are quantitatively different for each point.

Acupuncture Points↗
PubMed1995

Does the healthy hepatitis C virus carrier state really exist? An analysis using polymerase chain reaction.

To determine whether the presence of hepatitis C virus (HCV) viremia correlates with the severity of liver disease in anti-HCV-positive apparently healthy blood donors, we studied 98 blood donors found positive for anti-HCV using enzyme-linked immunosorbent assay (ELISA). Each subject underwent a liver biopsy, a test for HCV RNA in the serum by polymerase chain reaction (PCR), and a panel of liver injury tests. As a result, 97% of the anti-HCV-positive blood donors had some type of histological abnormality:22 (22%) had minimal changes, 1 (1%) had chronic lobular hepatitis, 40 (41%) had chronic persistent hepatitis (CPH), and 32 (33%) had chronic active hepatitis (CAH). Only 3 subjects had a normal liver histology. HCV RNA was detectable in the serum in 65% of the anti-HCV-positive donors. HCV RNA in serum was detectable in none of the donors with a normal liver histology, in 36% (confidence interval [CI], 17% to 59%) of those with minimal changes, in 70% (CI, 53% to 83%) of those with CPH, and in 87% (CI, 71% to 96%) of those with CAH (P = .00001). HCV RNA was detectable in 75% of the donors with elevated (> 45 U/L) alanine transaminase (ALT) values and in 59% of those with normal ALT levels (P = not significant). The incidence of chronic hepatitis was higher in HCV RNA-positive than in HCV RNA-negative donors (88% vs. 50%; P = .00005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Candida esophagitis and cytomegalovirus gastritis: optic and immunohistochemical diagnosis in an HIV+ patient].

Esophageal candidiasis, along with gastritis caused by cytomegalovirus--CMV--, is a common opportunistic infection in immunodepressed patients. A clinico-pathological description is made of a human immunodeficiency virus-positive female (group IV-C-2) with a history of odynophagia and dysphagia resistant to treatment. The light microscopy and immunohistochemical study of an endoscopic esophago-gastric biopsy allowed the diagnosis of moniliasic esophagitis associated with CMV-induced gastritis. Emphasis is placed on the efficacy of immunohistochemical techniques over other methods in diagnosing CMV infection.

Adult↗
PubMed1994

[Acute renal failure after the administration of enalapril as presentation form of Takayasu's arteritis].

The case of a 19 year old patient with Takayasu arteritis with exclusive involvement of the abdominal aorta and without involvement of the renal arteries who presented severe arterial hypertension during the acute phase of the disease is referred. The administration of a dose of 20 mg of enalapril maleate was followed in less than 24 hours by lameness of the lower limbs and acute oligoanuric renal failure, both of which were reversible after discontinuation of the drug. During the inflammatory phase of the disease, treatment with high doses of prednisone was effective in the control of the general symptoms and the biologic parameters of inflammation. Surgical revascularization was successfully carried out 5 months after diagnosis. Two years later the patient continues to be normotense and asymptomatic.

Acute Kidney Injury↗
PubMed1994

A lumbar chordoma treated with a wide resection.

Chordomas are rare skeletal tumors arising from the embryonic remains of the notochord [18, 30]. These tumors tend to appear in midline regions, particularly at the upper and lower extremities of the spinal column. We report the case of a 74-year-old woman with radicular compression associated with an L3 chordoma that was treated with a wide resection.

Aged↗
PubMed1994

Effect of three commercial starters on growth of Staphylococcus aureus and enterotoxins (A-D) and thermonuclease production in broth.

The growth of four enterotoxigenic Staphylococcus aureus strains was partially inhibited by three commercial starters used in the meat sausage industry when grown in APT broth at 30 degrees C statically. Starter SP318 (a mixture of selected strains of Lactobacillus sake, Pediococcus pentosaceus and Staphylococcus xylosus) showed the most inhibitory activity. Staphylococcal enterotoxins (A, B, C1 and D) synthesis was totally inhibited by the growth of the three starters, whereas staphylococcal thermonuclease production was partially inhibited in mixed cultures.

Animals↗
PubMed1994

Molecular cloning, sequencing and expression in Escherichia coli of the capsid protein gene from rabbit haemorrhagic disease virus (Spanish isolate AST/89).

We describe the cloning, nucleotide sequencing and expression in Escherichia coli of the major capsid component (VP60) from the Spanish field isolate AST/89 of rabbit haemorrhagic disease virus (RHDV). The sequence of the 3'-terminal 2483 nucleotides of the genome was found to be 95.4% identical to the German RHDV strain, showing ten changes in the deduced VP60 amino acid sequence. The gene coding for this structural polypeptide has been expressed in bacteria as a beta-galactosidase fusion protein or using a T7 RNA polymerase-based system. The VP60 fusion protein showed only partial antigenic similarity with native VP60 and did not confer protective immunity. The recombinant VP60 produced in the T7 RNA polymerase-based system was antigenically similar to the viral polypeptide as determined using polyclonal and monoclonal antibodies. When used to immunize rabbits the recombinant VP60 was able to protect the animals against a lethal challenge using purified RHDV.

Animals↗
PubMed1994

The extent of sodium and water administration associated with i.v. drug infusions in a surgical unit.

OBJECTIVE: To quantify sodium and water administered to surgical patients but not actually prescribed by the physician. METHODS: Computerized medication records of 1208 surgical patients who were operated on in 1992 were analysed retrospectively. Only prescriptions for intravenous (i.v.) drugs and fluids were selected. RESULTS: Thirteen of 143 i.v. drugs made up 68.3% of prescriptions for i.v. drugs. Patients received a median of three i.v. drugs daily. Patients were on i.v. therapy for a mean of 4.6 +/- 6.0 days (range 1-140, median 3 days). On 24% of patient-days, patients received more than 100 mEq of sodium which was not consciously prescribed, and on 20.4% of patient-days they had an extra daily intake of 750 ml of water or more. One fourth of the total sodium and more than 15% of fluid administered to patients was in the form of NaCl 0.9%, used as a vehicle for i.v. drugs. CONCLUSIONS: There is a considerable amount of sodium and water administered to patients without a specific prescription. The promotion of knowledge about the correct administration of i.v. drugs is an important task for the clinical pharmacist. If this is achieved, it will allow for an optimal administration of drugs as well as the prevention of possible side effects from an intended sodium and water administration.

Body Fluids↗
PubMed1994

Dialysis membranes and PTH changes during hemodialysis in patients with secondary hyperparathyroidism.

Changes in parathyroid hormone (PTH) during hemodialysis have been explained by the influence of ionized calcium changes on PTH secretion. In this study we have investigated the influence of dialysis membranes of different permeability on PTH changes during hemodialysis. Five chronic renal failure patients underwent three consecutive hemodialysis sessions with cuprophane (CUP) polysulfone (PS) and polyacrylonitrile (PAN). Two hours of isolated ultrafiltration were followed by 3 h dialysis. A significant decrease in carboxy terminal PTH (COOH PTH) was observed with PAN (p < 0.05) but not with CUP or PS. Intact PTH decreased (p < 0.001) with all three membranes, following a significant increase in ionized calcium (p < 0.001). Sieving coefficients for COOH PTH were significantly lower with CUP than with PS (p < 0.05) or PAN (p < 0.001). Intact PTH sieving coefficients were near zero for all three membranes. COOH PTH and intact PTH clearance rates were significantly higher with PAN (p < 0.001) than with PS or CUP, either in isolated ultrafiltration or with dialysis fluid. Thus PTH changes during hemodialysis do not only depend on the increase in calcium but also on the nature of the dialysis membrane. Adsorption of PTH to the PAN membrane surface explain the high PTH clearance rates achieved with this filter.

Acrylic Resins↗
PubMed1993

Long-term outcome in renal transplantation with terminal cutaneous ureterostomy.

We have reviewed the complications and follow-up in 6 patients who underwent kidney transplantation with cutaneous ureterostomy. Four patients had tuberculosis, 1 myelomeningocele and another congenital stenosis of the posterior urethra. Cutaneous ureterostomy was performed by suturing the edges of the distal end of the ureter to the skin. The mean follow-up was 40.6 months (range 2-105). The patient and graft survival rates were 83.3% and 66.6% respectively during the 249 months of total follow-up. Significant bacteriuria and leukocyturia were constantly present and the incidence of urinary infection was 3.1 episodes/patient/year. The early complications of the stoma were partial necrosis in 1 case and haematoma in another. The most frequent late complication was stomal stenosis requiring periodic dilatation. A plasma creatinine of 61.88 to 114.92 mumol/l reflected good long-term graft function in the remaining patients. Terminal cutaneous ureterostomy is a simple technique with good long-term results.

Adolescent↗
PubMed1993

Interaction of the peptide hormone adrenocorticotropin, ACTH(1-24), with a membrane model system: a fluorescence study.

The peptide hormone adrenocorticotropin and a related peptide were studied in solution and in interaction with a model system of membranes (small unilamellar vesicles of dipalmitoylphosphatidylcholine and 17% dimyristoylphosphatidylglycerol) via fluorescence spectroscopy. In aqueous solution, intramolecular distances between the fluorescent residues R(Tyr2-Trp9) = 9.2 A and R(Trp9-Tyr23) > or = 18 A were obtained, in agreement with molecular models. Interaction of the peptide with the negatively charged membrane is evident from the alteration of the Trp photophysical parameters (quantum yield, fluorescence spectra and anisotropy), with a partition constant between the lipidic and aqueous phase of Kp = 1-2 x 10(3). The existence of two populations of Trp in the membrane, which are distinctly accessed by acrylamide, was concluded from the tryptophan fluorescence quenching study; the two fractions are located near the membrane interface as inferred from its fluorescence quenching by the 5-doxylstearate and 16-doxylstearate lipophilic quenchers. This result is further supported by energy transfer experiments to the 3-(9-anthroyloxyl)stearic acid and 12-(9-anthroyloxyl)stearic acid probes.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1993

Modern microbiological methods for foods: colony count and direct count methods. A review.

Over the last years methods for enumeration of microorganisms in foods are changing rapidly. Techniques based on totally new concepts as well as instruments and miniaturized systems that allow the automation and simplification of existing microbiological procedures have been developed. These rapid methodologies should satisfy the increasing requirements for effective quality assurance of foods. In the present paper we review some of the more interesting methods based on colony count or direct bacterial count.

Animals↗