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Biomedical subjects

P Torres

Publications and source records attributed to P Torres.

At least 37 records · Page 2Linked to original sources
PubMed2000

[First description of concomitant infection with tuberculosis and paratuberculosis in dairy sheep in Argentina].

The authors present the results of a comparative intradermal tuberculin test performed on dairy sheep to determine rates of reaction to bovine and avian purified protein derivative (PPD). Test reactions were interpreted by palpation and measurement with a calliper. Results were analysed by plotting the values obtained. Agar gel immunodiffusion tests, growth in culture and histopathological examinations were also performed to allow differential diagnosis between tuberculosis and paratuberculosis. In the first tuberculin test, performed on 288 sheep, 74 animals showed a positive reaction to avian PPD (25.69%), two animals showed a positive reaction to bovine PPD (0.69%), and one animal was positive with respect to both tuberculins (0.34%). In the second test, involving 247 sheep, 55 demonstrated a positive reaction to avian PPD (22.26%), whilst none reacted to bovine PPD. The presence of Mycobacterium avium subsp. paratuberculosis was confirmed by culture and serological testing. In addition, lesions compatible with those caused by M. bovis were found by histopathological examination. These findings highlight the importance of the accurate diagnosis of tuberculosis and paratuberculosis for the effective control of both diseases.

Animals↗
PubMed2000

[Cultural characteristics of some ectomycorrhizal fungi in pure culture].

Macro and microscopic features for 21 species of ectomycorrhizal fungi are presented, with regard to their particular importance as possible taxonomic criteria. The culture media used are MMN and BAF. Cultural characteristics of some of our isolates, like color or morphology of the mycelia, were comparable to those observed by different authors for the same species, or species which are closely related taxonomically, as for example Boletus satanas and Lactarius deliciosus in BAF media, or Hebeloma edurum, Lycoperdon perlatum, Paxillus atrotomentosus, Rhizopogon roseolus and Suillus collinitus in MMN media. Macroscopically the color of mycelia, the amount of aerial mycelia and microscopically the exudates and the presence of inflated and flexuous cells were the most variable characteristics within species.

English Abstract↗
PubMed1999

Photovoltaic technology: the case for thin-film solar cells

The advantages and limitations of photovoltaic solar modules for energy generation are reviewed with their operation principles and physical efficiency limits. Although the main materials currently used or investigated and the associated fabrication technologies are individually described, emphasis is on silicon-based solar cells. Wafer-based crystalline silicon solar modules dominate in terms of production, but amorphous silicon solar cells have the potential to undercut costs owing, for example, to the roll-to-roll production possibilities for modules. Recent developments suggest that thin-film crystalline silicon (especially microcrystalline silicon) is becoming a prime candidate for future photovoltaics.

Journal Article↗
PubMed1999

Evaluation by Vickers indentation of fracture toughness of a phosphate biodegradable glass.

Indentation tests are commonly used for the evaluation of fracture toughness of brittle materials, particularly glasses and ceramics, because this technique requires only a small polished area on the specimen surface from which a large number of data points can be generated rapidly. However, a wide variety of equations for the calculation of fracture toughness of ceramic materials by means of Vickers indentation are available. Such equations are obtained phenomenologically and their parameters adjusted in such a way that the KIC values obtained are in good agreement with those obtained by conventional methods. This is the reason why it is necessary to check which type of equation reproduces more accurately the results obtained by means of conventional methods for the material which is going to be investigated. In the present work seven different fracture toughness equations widely used in glass and ceramic studies are considered and the results are compared with those obtained by conventional methods, such as single-edge notch beam (SENB) specimens tested in three-point bending. The role played by the applied indentation load is considered.

Journal Article↗
PubMed1999

Acanthocolpid metacercariae in the sea bass from Alejandro Selkirk Island, Chile.

Morphological characteristics of a metacercaria from muscle of 15 sea bass Caprodon longimanus (Serranidae) collected near Alejandro Selkirk Island (Chile) in the south-eastern Pacific Ocean indicate that it belongs to the genus Manteria (Acanthocolpidae). All metacercarie were encapsulated with connective tissue. The prevalence of infection was 100%, with 64% of metacercariae were located between dorsal pterygiophores and dorsal fin base. Mean intensities of metacercariae did not differ significantly with respect to sex of the fish. There was no significant correlation with intensities of infection and condition in the host.

Animals↗
PubMed1999

Pressure oscillations in anesthetized dogs and its conversion into quasi-periodic orbits.

Using a basic representation of dynamic systems, arterial blood pressure pulsation is converted into quasi-periodic orbits with the purpose of transforming a periodic phenomena into a cyclical one by plotting the pressure p(t) versus its first derivative dp/dt. This elementary mathematical procedure made it possible to evaluate the variability of the systemic arterial pressure pulsations, both systolic and diastolic, as well as the slope variability of the anachrotic and catachrotic phases. Two periods, which can be used to estimate different sources of variability, can be distinguished in the catachrotic phase. One corresponds to the open aortic valves, and the other is associated with the closed valves. Furthermore, through the first derivative of pressure oscillations we were able to identify small changes in arterial pressure, which appeared when the sampling rate was at least 150 samples per second. Since the time variable was converted into a parameter, the result was a synoptic or holistic approach, which is a considerable improvement for the visual analysis of cardiovascular phenomena. This simplified mathematical procedure can be easily implemented on a personal computer in real time and applied to all rhythmic phenomena in Physiology and Pathology.

Anesthesia↗
PubMed1998

Rapid, low-technology MIC determination with clinical Mycobacterium tuberculosis isolates by using the microplate Alamar Blue assay.

A colorimetric, microplate-based Alamar Blue assay (MABA) method was used to determine the MICs of isoniazid (INH), rifampin, streptomycin (SM), and ethambutol (EMB) for 34 Peruvian Mycobacterium tuberculosis isolates (including both pansensitive and multidrug-resistant strains) and the H37Rv strain by using bacterial suspensions prepared directly from solid media. Results for all isolates were available within 8 days. Discordant results were observed on initial tests for 3 of 16 INH-susceptible isolates, 5 of 31 EMB-susceptible isolates, and 2 of 4 SM-resistant isolates (by the BACTEC 460 system). The overall agreements between the MICs obtained by MABA and the results obtained with the BACTEC 460 system were 87.9% for initial results and 93.6% after retesting 12 of 17 samples with discrepant results. Interpretation of MABA endpoints improved with technical experience. The MABA is a simple, rapid, low-cost, appropriate technology which does not require expensive instrumentation and which makes use of a nontoxic, temperature-stable reagent.

Antibiotics, Antitubercular↗
PubMed1998

[Uveitis].

Uveitis is a general term that refers to the inflammation of uveal tract, which is an important cause of blindness in young people. It is well known that uveitis can be the initial manifestation of a systemic disease (S.D.), and may appear years before the diagnosis of the primary disease. Uveitis should be integrated in a systemic study with proper testing. Therefore, the diagnosis is a matter for the ophthalmologist and the Specialist in internal medicine. We have made a retrospective study of 71 patients with chronic uveitis or panuveitis. We found 54.9% of primary uveitis and 45.1% of S.D. associated uveitis, most of them with Behçet's disease (16/71) and Ankylosing Spondilytis (7/71). HLA typing of the patients showed a decreased frequency of HLA A1 and HLA A3 antigens and an increased frequency of the HLA B27 antigen, when compared to a Portuguese control population. We confirmed the important role of HLA B27 as an independent susceptibility factor for anterior uveitis. The lowest HLA A3 frequency was observed in the group of S.D. associated uveitis, which could suggest that this antigen may play a role as a factor of resistance to uveitis.

Adolescent↗
PubMed1997

Human case of gastric infection by a fourth larval stage of Pseudoterranova decipiens (Nematoda, Anisakidae).

Only three cases of human infection by anisakid nematodes have been reported in Chile since 1976. In the present case, an anisakid worm, identified as a fourth-stage Pseudoterranova decipiens larva, was removed with a gastroendoscopic biopsy clipper from the stomach of a 45 year-old man from southern Chile. The patient, who presented acute epigastric pain and a continuous sensation of having an empty stomach, reported having eaten smoked fish. The worm was fixed in 70% ethanol and cleaned in lactophenol for morphological study. The morphometric characteristics of the worm are described and drawn. Anisakid larvae in fish flesh can be killed by freezing or cooking.

Animals↗
PubMed1997

Diplostomatid metacercariae in the brain of silversides from Lake Riñihue, Chile.

The tissue locations and effects produced by metacercariae of Diplostomum (Austrodiplostomum) mordax and Tylodelphys destructor in the brain of 30 silversides (Basilichthys australis) from Lake Riñihue in Chile, were evaluated. Metacercariae were mainly observed in the interlobular infoldings, meninges and ventricles of the brain. The prevalence was 18 (60%) and the intensities were usually low (1 to 9 metacercariae), with no inflammation or invasion of the parenchyma, except for one fish which had 130 parasites associated with a moderate inflammatory reaction. Asymmetry in the distribution of metacercariae in the cerebral hemispheres was observed in one (3%) of the 30 fish.

Animals↗
PubMed1997

Genetic association study between pathological gambling and a functional DNA polymorphism at the D4 receptor gene.

A Spanish sample consisting of 68 Caucasian pathological gambling patients (47 males and 21 females) and 68 unaffected controls were screened by the molecular analysis of a functional DNA polymorphism in the locus for the D4 dopamine receptor gene. Our results are consistent with the existence of a significant association between genetic variants at a DRD4 gene polymorphism and pathological gambling (chi 2 = 11.82; P = 0.037). This association seems to be sex-influenced, since there was no significant association when only males were considered (chi 2 = 9.45; P = 0.09), but there was a more significant association if we only considered female subjects (chi 2 = 8.73; P = 0.033). Individuals with the longest allele (D7) were the most frequent in affected females (chi 2 = 4.50; P = 0.033). This work provides a new evidence of the implication of the dopaminergic reward pathways, now through the involvement of DRD4, in the aetiology of this impulsive disorder.

Alleles↗
PubMed1997

[Determination of the cytokine level during storage of partially leukocyte-depleted (<0.5 x 10(9)) or totally leukocyte-depleted (<0.5 x 10(6)) platelets].

PURPOSE: To evaluate the levels of interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) during the storage of pools of PCs obtained after removing the buffy-coat, in comparison with the amount of leukocytes present in these components. MATERIAL AND METHODS: Blood was collected in quadruple-bag-system containing 63 mL of CPD as anticoagulant and 100 mL of SAG-M solution as additive for the red cells. Approximately twelve hours after collection, blood separation was made automatically by Compomat (NPBI) and platelet concentrates were prepared from the buffy-coat fraction. Five or six PCs were mixed to obtain a pool (n = 28). Eight pools were WBC reduced by filtration (PXL-8, Pall España). Before storage a sample of each pool was obtained in order to count platelets and WBC as basal values. All kind of pools were stored at room temperature with continuous agitation during a period of 10 days. Volumes were measured by weight and specific gravity. Platelets and leukocytes were counted in the Coulter-counter (STKR Counter. Izasa) or in Nageotte chamber for the filtered products. On days 1, 4 and 7 interleukins were measured by ELISA (EASIA Kits, Medgenix Diagnostics, Brussels), Lecture was done at 450 nm using a spectophotometer (ANTHOS 2001). Lower limits of sensitivity were 2 pg/mL for IL-1 beta and 3 pg/mL for IL-6 and TNF-alpha according to the manufacturer. Wilcoxon test was used for statistical analysis. RESULTS: The average volume of the pools was 460 mL and 374 for the filtered ones. The total platelet amount was 3.63 x 10(11) and 2.8 x 10(11) respectively, with a WBC contamination of 380 x 10(6) and 0.54 x 10(6) for the filtered. The yield of platelets after filtration was 84% with a loss of 99.90% of WBC (3-log). The measures of interleukins were not homogeneous, but a great variability was found shown among the different pools, not always in relationship with the amount of leukocytes. The levels of IL-1 beta were 3.58 pg/mL on day 1, 6.36 pg/mL on day 4 and 8.76 pg/mL on day 7 (p < 0.005). For the IL-6 we found 13.08 pg/mL on day 1, 15.43 pg/mL on day 4 and 19.77 on day 7 (p < 0.05). For the TNF-alpha, 13.65 pg/mL an day 1,24.33 pg/mL on day 4 and 30.10 pg/mL on day 7 (p < 0.05). In the filtered pools the detections of IL-1 beta and IL-6 were always under the sensibility threshold, but there was an increment of TNF-alpha on day 7 (16.91 pg/mL). Microbiologic cultures were always negative. CONCLUSION: The accumulation of IL-1 beta, IL-6 and TNF-alpha is not prevented by the fact of removing the buffy-coat layer when preparing PCs, although these levels are considerably lower in comparison with those obtained by the PRP technic. Filtration of pooled PCs avoids the presence of these cytokines except TNF-alpha, where a low amount can be detected.

Blood Platelets↗
PubMed1996

Experimental flail chest: ventilatory function with fixation of flail segment in internal and external position.

UNLABELLED: The effect on ventilatory function of fixation of a flail segment in internal (FIP) and external (FEP) position and oxygen administration was studied in an experimental flail chest with pleural indemnity. Variations of tidal volume (TV), respiratory rate (RR), minute volume (MV), and arterial blood gases are reported. These parameters were measured in nine dogs in control and flail conditions (FC). The effect of FIP, FEP, and oxygen administration were studied. RESULTS: Significant differences were found: TV decreased from control values to FC and from FC to FIP, but increased from FC to FEP. RR values increased from control to FC and from FC to FIP, but decreased from FC to FEP. MV values decreased from FC to FEP. TV, RR, and MV were not changed under oxygen administration. Hypoxemia or hypercapnia were not observed. It was concluded that FIP is deleterious for respiratory mechanics, whereas FEP improves ventilatory parameters.

Animals↗
PubMed1995

A weak association between TH and DRD2 genes and bipolar affective disorder in a Spanish sample.

Genetic factors play an important role in the aetiology of bipolar affective disorder (BP). So far, results of linkage studies have been largely disappointing. We have searched for a possible association between polymorphic DNA markers of two candidate genes (tyrosine hydroxylase, TH; dopamine D2 receptor gene, DRD2) and BP in a population from central Spain. Our results are consistent with the existence of a weak association between these two genes and BP, in such a way that TH and DRD2 could be considered as minor genes contributing to susceptibility.

Adult↗