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Biomedical subjects

P Torres

Publications and source records attributed to P Torres.

At least 19 recordsLinked to original sources

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

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

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

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

[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

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

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

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

[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

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

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

Factors associated with Taenia solium cysticercosis: analysis of nine hundred forty-six Peruvian neurologic patients. Cysticercosis Working Group in Peru (CWG).

In most developing countries, 10% of acute neurologic cases are patients with neurocysticercosis (NCC). Determining specific factors associated with contracting NCC will facilitate its diagnosis and prevention. We examined multiple socioeconomic, demographic, environmental, medical, and behavioral characteristics of 946 Peruvian neurologic patients for a correlation with NCC, which was diagnosed by the highly specific and sensitive electroimmunotransfer blot (EITB) or immunoblot assay. Eighteen percent (172 of 932) of serum samples and 28% (101 of 362) of cerebrospinal fluid samples were EITB-positive. The proportion of EITB-positive persons was similar for all socioeconomic levels. Significant factors associated with NCC were: 1) being born outside Lima, 2) having raised pigs, 3) more than 20 years of age, 4) a history of seizures, and 5) a history of taeniasis. Of these factors, raising pigs is the only one that is amenable to intervention, via improvements in animal husbandry.

Adolescent

[Blood fractionation based on the extraction of the buffy-coat layer. Analysis of our results].

PURPOSE: To compare a procedure of blood processing via a quadruple bag for the preparation of white-cell-poor blood components with the results obtained with triple-bag-system, in order to adopt it as routine in our blood centre. MATERIAL AND METHODS: Blood was collected in 289 quadruple-bag-system containing 63 mL of CPD as anticoagulant and 100 mL of SAG M solution as additive for the red cells. We used 237 standard quadruple-bags supplied by Fenwal (195) and NPBI (42), and 52 of the top-and-bottom system supplied by Fenwal. Blood separation was made automatically by CompomatR (NPBI) and platelet concentrates were prepared from the buffy-coat fraction. Standard bags were processing as follows: After the first centrifugation of the whole blood (28,800 g), the plasma was transferred into the 300-mL bag until the interface of red cells and plasma was detected; then approximately 80 mL of plasma and buffy-coat (BC) were collected into the 100-mL satellite bag. Top-and-bottom bags were centrifuged at 43,500 g., the red-cells were transferred into the bottom-bag containing SAGM, and plasma was transferred into the top-bag. The buffy-coat fraction remains in the original bag. In both procedures, platelet concentrates were prepared from buffy-coat fraction. After the centrifugation of this fraction (1,400 g and 1,600 g), the supernatant (concentrated platelets in plasma) was transferred into a 300-mL bag and the bag with the residual buffy-coat was then discarded. 287 triple-bags were separated in the traditional way, using platelet-rich plasma (PRP) as a source for the preparation of platelet concentrate (PC). Volumes were measured by weigh and specificity gravity. Platelet, leukocytes and red-cells were counted in the Coulter-Counter (STKR.Izasa). T-Student test and Chi2 test were used for statistical analysis and p < 0.05 was taken as a significant difference between samples. RESULTS: The three kinds of quadruple-bags showed results very homogeneous with little differences. For all brand of bags packed-red-cells showed a volume of 300 +/- 2.9 mL, EVF of 51.9 +/- 0.7%. The recovery of red cells into the packed red cells and of platelets into the platelet concentrate was 90 +/- 0.4 percent and 69 +/- 2 percent respectively, of the original value. White cells in the packed red cells were 9.7 +/- 03 x 10(9) with recovery of 30.1 +/- 1.4 percent of the original value; statistical difference was found in comparison with triple bags PRC (p < 0.001). The PC volumes averaged 71 +/- 1 mL and the overall mean platelet concentration was 77 +/- 2 x 10(9). Eighty three percent of PC contained more than 55 x 10(9). White cells contamination of platelet concentrates was 0.283 +/- 0.039 x 10(9), with a recovery of 9.5 +/- 1.5 percent of the leukocytes present in the whole blood. This value is below the threshold that prevents febrile reactions and microaggregate formation. The plasma yield in the quadruple-bag system was much greater than that in the triple-bag system (p < 0.001). With this process we removed about 77 +/- 0.5 percent of the plasma present in the original unit in comparison with 56 +/- 1 percent removed in that of the triple-bag system. CONCLUSION: With this procedure leukocyte-poor blood components are obtained in which more of 90 percent original white cells have been removed, with a red-cell recovery of 90 percent. Moreover, the plasma yield is also excellent.

Blood Platelets