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Biomedical subjects

C Piña

Publications and source records attributed to C Piña.

15 recordsLinked to original sources
PubMed2006

Metal corrosion in bones implanted with Zinalco--a SAXS and NMR study.

The composition and morphology of bones implanted with stainless steel (316L-SS) and a metal alloy made of zinc, aluminum, and copper (Zinalco) are compared. Small-angle X-ray scattering (SAXS) and nuclear magnetic resonance (NMR) results show that with time Zinalco is corroded and zinc, aluminum, and copper diffuse into the osseous tissue, promoting nonhomogeneous bone. Instead, 316L-SS does not incorporate into bone, and the bone recovers homogeneously at a lower speed.

Aluminum↗
PubMed2005

Disinfection of dairy and animal farm wastewater with radiofrequency power.

Radiofrequency (RF) power was investigated as a new, physical (nonchemical), thermal process to disinfect wastewater from dairy and animal facilities. Samples (n = 38) from 8 dairy, 2 calf, and 3 swine facilities in California were collected over a 3-yr period and characterized for their dielectric properties, chemical composition, and suitability for thermal processing using RF power. To establish efficacy for disinfection, selected samples were inoculated with high levels (10(6) to 10(9) cfu/mL) of bacterial pathogens such as Salmonella sp., Escherichia coli O157:H7, and Mycobacterium avium ssp. paratuberculosis and processed with an RF prototype system. The capabilities of RF power as a method for thermal disinfection of wastewater were demonstrated when bacteria pathogens were completely and rapidly (<1 min) inactivated when temperatures of 60 to 65 degrees C were achieved. Furthermore, RF technology can be used for large-scale, batch or continuous and portable applications, allowing significant improvements in energy-use efficiencies compared with conventional thermal (surface heating) technologies. Therefore, RF power has potential as an alternative to disinfect dairy/animal farm wastewater before recycling.

Agriculture↗
PubMed1999

Biocompatibility in vitro tests of Zinalco.

In this study, cultures of human lymphocytes were exposed for 48 h to aqueous suspensions of Zinalco, with different times of corrosion, to test the biocompatibility of this alloy and support its use in medical implants. The results show that the Zinalco concentrations assessed affect the mitotic index (MI) and some also increase the length of DNA migration measured in the comet assay in a significant manner; none of them showed clastogenic nor aneugenic effects. The authors conclude that Zinalco may be considered as an alternative biomaterial and suggest its use for short-term implants.

Adult↗
PubMed1998

Preliminary histological study of connective tissue response to Zinalco and stainless steel 316L implants after 120 days.

Circular plates of Zinalco alloy (80 wt% Zn, 1.5 wt% Cu, 18.5 wt% Al) and stainless steel (SS) 316L were implanted in 12 female Wistar rats subcutaneously and intramuscularly to compare organism response, 120 days after implantation. The tissues surrounding the implants were analysed employing hematoxilin and eosin (H-E) and Gallego's trichromic techniques (GTT). Findings indicate that the reaction to Zinalco alloy was similar to the reaction to SS 316L. The Zn, Al and Cu concentrations in blood were measured, without evidence of any alteration due to implants. The presence and distribution of Zn, Al and Cu components of Zinalco alloy were detected in tissues by energy dispersive X-ray microanalysis.

Journal Article↗
PubMed1998

[Improvement in diastolic function in hypertensive patients with left ventricular hypertrophy with inhibitors of the angiotensin converting enzyme].

An open and multicentric study was conducted with 66 patients with mild to severe diastolic arterial hypertension and echocardiographic left ventricular hypertrophy, the evolution of diastolic function, by means of doppler transmitral flow echocardiography, under treatment with ramipril, an angiotensin converting enzyme inhibitor, at a dose of 2.5 and 5 mg/day, or combined with a diuretic, after three and six months of treatment. Despite not obtaining the tensional control in all patients, a decrease in the mass, both in absolute values and mass index, was obtained. This decrease was observed both in male and female patients from the first three months, which went on until the sixth month, thus suggesting an independent action of the hemodynamic load decrease for the obtention of this effect. There was also a change in the ventricular geometry with a displacement of patients from concentric enlargement to normal, remodelling and eccentric enlargement. The diastolic function improved both for the early and for the late maximal filling velocity, relationship between both, and deceleration time, although the time during which this improvement occurred was different for each parameter, thus indicating the different influence of the dynamic and structural factors on these parameters. No correlation was found between the improvement in diastolic function and hypertrophy regression. We can conclude that ramipril is useful for the control of the left ventricular hypertrophy and diastolic function, irrespective of arterial tension values.

Aged↗
PubMed1997

Comparison of the InPouch TV culture system and Diamond's modified medium for detection of Trichomonas vaginalis.

This study compared the use of Diamond's modified medium to InPouch for the culture of Trichomonas vaginalis from pooled vaginal secretions. The sensitivity for InPouch was 82.4% (61/74) versus 87.8% (65/74) for Diamond's modified medium. There were no significant differences in the sensitivity and negative predictive value of InPouch compared to Diamond's modified medium.

Adult↗
PubMed1991

VP4 monotype specificities among porcine rotavirus strains of the same VP4 serotype.

The porcine rotavirus OSU strain was used to produce monoclonal antibodies (MAbs) directed against the outer capsid protein VP4. From two separate fusions, eight MAbs that inhibited hemagglutination activity of the OSU strain were selected. All MAbs immunoprecipitated both the OSU VP4 protein derived from a lysate of infected MA104 cells and the OSU VP4 protein expressed in Sf9 cells by a recombinant baculovirus. By immunoprecipitation of in vitro-translated OSU gene 4 transcripts of different length, the eight MAbs were found to be specific for the VP8 subunit of VP4. All MAbs neutralized the OSU strain but failed to neutralize human, bovine, and simian rotavirus strains. Antiserum to the expressed OSU VP4 protein was used to study the distribution of VP4 antigenicity among porcine rotaviruses. At least two distinct specificities were identified among 14 rotavirus strains that had been previously assigned to four distinct VP7 serotypes. Five groups of monotype specificities of the VP4 protein were identified by the eight anti-VP4 MAbs among 11 porcine strains that share the same VP4 serotype.

Animals↗
PubMed1982

Clobazam: single or divided doses?

The results of treatment of neurotic disorders with single or divided daily doses of the anxiolytic drug clobazam have been compared. The trial was performed in two groups, each of 57 patients, paired according to age, sex, diagnosis, severity of initial disorder, and total daily dose. The 114 subjects formed a random subgroup from a total of 1369 patients taking part in a postmarketing surveillance trial of clobazam. In view of the changes in the overall severity of the symptoms, in "persistent anxiety" and "anxiety crises", in "sleep disorders", the global clinical impression and the tolerance, it is concluded that clobazam is a useful drug in the treatment of anxiety, and that single or divided daily dosage schedules produce similar results.

Adult↗
PubMedDate not supplied

[Design and development of a stent (SAQ) for the treatment of arterial coronary arterioscleotic obstruction].

The practice of percutaneous transluminal coronary angioplasty has shown that the major complications are acute dissection as well as suboptimal results and restenosis. The effort to reduce these complications has led to create an intravascular device called Stent. The technology is complex and very expensive, for this reason we designed and made a new model of stent named SAQ. We introduce: The methodology of development, fabrication and modifications of a new intravascular device Stent SAQ. The results obtained in coronary arteries of ex vivo hearts of pigs and humans. The results in two model of animals, rabbit aorta and peripheral arteries in dogs. This investigation at this phase, shows satisfactory properties of SAQ which is secure and effective, with similar properties to the stents in use.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

[Effect of position with respect to gravitational force on the hydrodynamics of an experimental model of saccular aneurysm].

We wish to confirm the hypothesis that the hydrodynamics of brain aneurysms depend partially on their position, with respect to the force of gravitation, and so developed an experimental model of latex aneurysms, which was subjected to a pulsatile flow. Four different registers were made with an injection of ink and radioisotopes. A physical model was designed which allowed a quantitative analysis of the results and which allows a mathematical analysis of the aneurysm's hydrodynamics. The results suggest that when an aneurysm is oriented against the force of gravity, it has a very low risk of thrombosis, and the scarce turbulence of the flow condition a lower risk of growth and rupture, in comparison with other conditions. The greatest flow turbulence against the wall is found in the aneurysm oriented downwards, that is parallel to the force of gravity. Due to its hydrodynamics, the downwards aneurysm has the highest probability of complication, since it has; a) higher risk of rupture due to the impact of the stream upon the wall and to the turbulence this impact produces, b) a higher risk of thrombosis produced by the circulatory stasis which has a dome. This combination of factors (rupture and thrombosis) allows these aneurysms to grow more than others.

Gravitation↗
PubMedDate not supplied

[Characteristics associated with under-registration of children's deaths in the state of Guerrero, Mexico].

OBJECTIVE: To estimate the frequency of under-registered children deaths in rural areas and to identify associated characteristics. MATERIAL AND METHODS: The study was conducted in three stages. In the first, three strata of communities were formed according to the number of inhabitants; then a representative number of villages was randomly selected from each stratum. A census was made in each village to determine the deaths occurred between June 1993 and July 1994. In the second stage, the verbal autopsy method was used with the mothers of the dead children to determine the cause of death and investigate the study variables. In the third stage, registration of death was verified through the death certificates. RESULTS: An under-registration frequency of 68.9% was found; in communities of less than 500 inhabitants under-registration reached 73.2% and in larger communities it was 60.5%. Characteristics associated to under-registration were the lack of birth and death certificate, age younger than one month, lack of information on the concept and purpose of a Public Registration Office, distance from the Public Registration Office and to the doctor of more than 30 minutes, and community smaller than 1,000 inhabitants. CONCLUSIONS: A modification in the current organization of the death registration procedure is proposed and the use of a birth certificate designed by the National Health System.

Adolescent↗