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Biomedical subjects

A Lopez

Publications and source records attributed to A Lopez.

At least 361 records · Page 20Linked to original sources
PubMedDate not supplied

The participation of aortic proteins in the formation of complexes between low density lipoproteins and intima-media extracts.

SUMMARY: A factor of protein nature that forms specific complexes with low density lipoproteins (LDL) has been detected in extracts of aortic intima-media from men and rabbits. Although the formation of complexes is maximal at low ionic strength, it is still observed under physiological conditions. Gel electrophoresis of the complex formed between the extracts and LDL proteins indicates that the insoluble material is an aggregate of the lipoproteins with some of the proteins present in the extracts. Pretreatment of the intima-media extract with proteases greatly diminishes its complexing ability. The interaction was also observed between the extracts and sera. The sera from patients with myocardial infarct formed more insoluble complexes than the sera from a control group. The lipoprotein complexing agent was found in intima-media of aorta and coronary arteries but not in that of veins, pulmonary arteries or in the adventitia of arteries or veins.

Animals↗
PubMedDate not supplied

Thyrotropin-releasing hormone metabolism is attenuated in the cerebrospinal fluid of the human neonate.

The present study was designed to investigate the ontogeny of thyrotropin-releasing hormone (TRH) metabolism in human cerebrospinal fluid (CFS). The activity of pyroglutamate aminopeptidase (EC 3.4.11.8), the major enzyme catalyzing TRH metabolism in human CSF, was measured in CSF of 11 premature infants (gestational age, 29-39 weeks; birth weight, 1774 +/- 274 g), 8 newborn infants (term delivery; birth weight, 3648 +/- 240 g), and 11 adults (mean age, 29.6 +/- 1.5 years). Pyroglutamate aminopeptidase activity in CSF of premature and newborn infants was significantly lower (p less than 0.05) than that of adult CSF. These observed differences in the enzymatic activities were not due to changes in the affinity of the enzyme for its substrate TRH or the presence of enzyme inhibitor(s)/stimulator(s).

Adult↗
PubMedDate not supplied

A rare case of inferior venacaval type of atrial septal defect in an adult: echocardiographic features.

We report a rare type of atrial septal defect with communication between the left atrium and the inferior vena cava. This type of defect has been referred to as a low sinus venous type of atrial septal defect because of its developmental origin, and possibly is caused by defective absorption of the left venous valve of the sinus venosus into the septum secundum. Detailed echocardiographic features are discussed.

Aged↗
PubMedDate not supplied

An in vitro study of dural lesions produced by 25-gauge Quincke and Whitacre needles evaluated by scanning electron microscopy.

BACKGROUND AND OBJECTIVES: A study using scanning electron microscopy showed that although the laminas forming the dura mater are concentric and parallel to the surface of the medulla, the fiber layers' orientations are different in each sub-lamina, dispelling the conventional knowledge that all the fibers of the dura are arranged in a parallel direction. Thus, this study evaluated the dural lesions produced by Whitacre and Quincke spinal needles in the external and internal surface of the dura mater of the lower spine area in an attempt to gain more insight into the pathophysiology of postdural puncture headaches (PDPH). METHODS: The T11-L4 dural membranes from 5 fresh (immediately after extraction of organs for transplantation), male patients declared brain dead, ages 23, 46, 48, 55, and 60 years, were excised by anterior laminectomy. Morphologic orientation of the membrane and normal pH were maintained with an apparatus designed for this purpose. One hundred punctures (20 on each sample) at 90-degree angles were done with a new needle each time, 50 with 25-gauge Whitacre and 50 with 25-gauge Quincke needles. Half of the punctures with the Quincke needles were done with the bevel in parallel direction to the axis of the spinal cord, and the rest with the bevel perpendicular to it. Fixation in solutions of 2.5% glutaraldehyde phosphate buffer, followed by dehydration with acetone, was done 15 minutes after the punctures. After acetone was removed at ideal conditions of temperature and pressure, the specimens were then metallized with carbon followed by gold and inspected under a scanning electron microscope. RESULTS: Twenty-five of the Whitacre and 23 of the Quincke punctures were found for evaluation. There were no differences in the cross-sectional area of the punctures produced by the Whitacre or Quincke needles on the dura. The area of the dural lesions produced by 25-gauge Quincke needles, 15 minutes after they have been withdrawn, was 0.023 mm2 (confidence interval [CI] 95%, 0.015 to 0.027) in the external aspect (epidural surface) and 0.034 mm2 (CI 95%, 0.018 to 0.051) in the internal aspect (arachnoid surface) of the dural sac. The area of the lesions produced by the 25-gauge Whitacre needles was 0.026 mm2 (CI 95%, 0.019 to 0.032) and 0.030 mm2 (CI 95%, 0.025 to 0.036) in the external and internal surfaces of the dural sac, respectively. There were no significant differences in the cross-sectional areas of the punctures produced by the 25-gauge Whitacre or 25-gauge Quincke needles. Moreover, with Quincke needles the dural lesions closed in an 88.3% (CI 95%, 86.3 to 92.4) and 82.7% (CI 95%, 74.1 to 90.9) of their original sizes in the epidural and arachnoid surfaces, respectively. With Whitacre needles, the closure occurred in an 86.8% (CI 95%, 83.8 to 90.3) and 84.8% (CI 95% 81.7 to 87.3) in the dural and arachnoid surfaces, respectively. However, there were differences in the morphology of the lesions. The Whitacre needles produced coarse lesions with significant destruction in the dura's fibers while the Quincke needles produced a 'U'-shaped lesion (flap) that mimics the opened lid of a tin can, regardless of the tip's direction. CONCLUSIONS: The needles produced lesions in the dura with different morphology and characteristics. Lesions with the Quincke needles resulted in a clean-cut opening in the dural membrane while the Whitacre needle produced a more traumatic opening with tearing and severe disruption of the collagen fibers. Thus, we hypothesized that the lower incidence of PDPH seen with the Whitacre needles may be explained, in part, by the inflammatory reaction produced by the tearing of the collagen fibers after dural penetration. This inflammatory reaction may result in a significant edema which may act as a plug limiting the leakage of cerebrospinal fluid.

Adult↗
PubMedDate not supplied

Obligate nasal breathing in an elderly woman: increased risk of nasogastric tube feeding.

The initiation of oronasal breathing when the nasal pathway becomes obstructed requires a complex interaction of neuromuscular responses which are normally present in all but very young infants. We describe an elderly lady who developed respiratory failure partially due to an inability to initiate oral breathing when her nasopharynx was compromised by a nasogastric tube.

Aged↗
PubMedDate not supplied

Cumulative pregnancy rates and probability of pregnancy in various indications for intrauterine insemination.

A total of 122 patients were evaluated in a retrospective study for the cumulative pregnancy rate after intrauterine insemination. The indications included idiopathic infertility, anovulation, male factor, poor postcoital test, endometriosis, and pelvic factor. The cumulative pregnancy rate by 3 cycles or less varied from 7.7 to 43.5%. The highest pregnancy rate was for the group with poor postcoital test. There was no increase in pregnancy rate after 3 cycles of treatment. The concentration and motility of sperm were not significantly different between pregnant and nonpregnant groups.

Adult↗
PubMedDate not supplied

Scanning and transmission electron microscopy of a craniopharyngioma: x-ray microanalytical study of the intratumoral mineralized deposits.

This paper discusses the value of scanning electron microscopy (SEM) and x-ray microanalysis in the classification of craniopharyngiomas. This neoplasm shows epithelial nest, cords of cuboid cells, foci of squamous metaplasia, and microcystic degeneration. SEM reveals that the epithelial cysts are lined with elongated cells that possess numerous microvilli and blebs and that some cysts are lined with polyhedral cells. The microvilli are interpreted as characteristic of the fast growing craniopharyngiomas. A microanalytical study of the calcified areas reveals the presence of magnesium, phosphorus, and calcium.

Calcinosis↗
PubMedDate not supplied

Role played by a natural channel on the quality of bordering environment: a chemical assessment.

Based on a rational and simple chemical approach, a field-investigation aimed to assess the role played by a natural channel "lama" on the quality of underlying groundwater and neighbouring soils has been carried out. The results have demonstrated that: (a) the stream flowing through the "lama" is mainly made up of treated effluent from a nearby municipal wastewater treatment plant; (b) the occurrence of nitrates in the "lama" is due to rain-washing of nitrogen fertilized agricultural soils bordering on the "lama"; (c) hydraulic connections exist between the lama and the underlying groundwater causing contaminants flowing through the "lama" to reach groundwater within less than one week; (d) compared with the values measured in the "lama", the concentrations of TOC, N-NH4 and N-NO3 in groundwater result: lower, far lower and greater, respectively; (e) agricultural soils bordering on the "lama" result significantly contaminated by halogenated organics.

Agriculture↗
PubMedDate not supplied

Treatment options for tannery wastewater. I: Alkalinization with or without post-ozonation.

This is the first of two papers each dealing with a specific technological option for replacing the Fenton's reagent with simpler processes for treating industrial wastewater. In particular, the paper reports the results of an investigation aimed to check, at lab scale, the effectiveness of a chemical process (i.e., alkalinisation with or without post-ozonation) for treating tannery wastewater whose residual COD, measured after conventional biological treatment, result still higher than the Italian COD Maximum Allowable Concentration (MAC) value (i.e., 160 mgO2/L). The results have demonstrated that when the value of residual COD lies in the range 200 divided by 250 mgO2/L, a simple alkalinisation with NaOH, up to pH 12.5, allows to reach the MAC value with an alkali consumption equivalent to the acid consumption required by the Fenton treatment and with a chemical sludge production significantly lower, i.e. approximately 0.7 kg(dry)/m3 instead of approximately 1.5 kg(dry)/m3. Conversely, when the value of the residual COD lies in a higher range (i.e. 300 divided by 350 mgO2/L), in order to reach the COD MAC value, alkalinisation (from pH 8 to pH 12.5) must be followed by an ozonation post-treatment. From the chemical stand point, the paper clearly demonstrates that analyzing only simple "gross parameters" (i.e., TSS, TOC, COD, BOD5 and EC20) it is possible to get useful information about the chemical properties of the organic pollutants occurring in tannery wastewater.

Hydrogen Peroxide↗