PubMed Health⌕ Search

Biomedical subjects

J C Ortiz

Publications and source records attributed to J C Ortiz.

10 recordsLinked to original sources
PubMed2006

Bioactivation of a cobalt alloy by coating with wollastonite during investment casting.

Cobalt alloy samples were bioactivated during investment casting. The cavities of the investment mold were previously coated with wollastonite. Additionally, before coating with wollastonite, some mold cavities were filled out with graphite rods to avoid a chemical reaction between the wollastonite powder and the investment material. Half of the cast samples were heat treated at 1220 degrees C for 1 h. To perform the in vitro bioactivity assessment, the cast and heat-treated samples were immersed in a simulated body fluid solution (SBF) for a period of 21 days. The surface of the samples before and after immersion in SBF was characterized by SEM, EDX, and XRD analyses. During the casting, particles of pseudowollastonite were embedded on the metallic surface. After immersion of the samples in SBF, a ceramic layer was formed on both the alloy obtained by using the investment mold and the alloy obtained by using the graphite-filled cavity. The ceramic layer was thicker on the alloy cast in the investment mold. The layer was identified as hydroxyapatite by XRD analysis, in all the cases. The heat-treated samples after immersion in SBF showed the formation of a thin homogeneous layer consisting of fine grains of apatite.

Alloys↗
PubMed2001

The axillopectoral muscle (of Langer): report of three cases.

The axillopectoral muscle, usually called Langer's axillary arch instead of Langer's arm arch, is a supernumerary muscle and is the principal anatomic variation of the axilla. Three cases of the muscle were observed originating from latissimus dorsi crossing over the axillary neurovascular bundle and inserting deep to the insertion of pectoralis major or into the coracoid process. Clinicians should be aware of its existence as it can give rise to different pathologies. It should be recognised and excised to expose the axillary artery and vein in patients with trauma and to perform axillary lymphadenectomy or axillary bypass. It should be considered in the differential diagnosis of axillary masses or in a history of intermittent axillary vein obstruction. If the muscle causes problems its excision should be curative.

Aged↗
PubMed1996

The efficacy and optimum time of administration of ranitidine in the prevention of the acid aspiration syndrome.

In order to evaluate the efficacy of a single oral dose of ranitidine 150 mg and the optimum time for its administration, we studied pH and volume measurements in 138 surgical patients, who formed six groups according to the time elapsed from ranitidine administration to gastric fluid aspiration as follows: group A: no ranitidine, group B: 60-90 min, group C: 91-120 min, group D: 121-150 min, group E: 151-180 min and group F: > 180 min. The patients from groups B, C, D, E and F had a significant increase in gastric pH and a significant decrease in gastric fluid volume when compared to the patients from group A. 33.3% (95% CI 16.63-53.22%) of patients in group A were deemed 'at risk' of acid aspiration compared to 0.9% (95% CI 0.02-4.90%) in the other groups. No significant differences were found between the patients receiving ranitidine after 60 min with respect to risk of acid aspiration. It is concluded that a single oral dose of ranitidine 150 mg is effective against the acid aspiration syndrome 60 min after administration.

Adult↗
PubMed1995

Allozyme variation in populations of Pleurodema thaul (Lesson, 1826) (Anura; Leptodactylidae).

Genetic variation of 18 loci detected in 13 Chilean and one Argentinian population of the toad Pleurodema thaul are described. Seven loci were polymorphic in at least one of the studied populations. The average heterozygosity values observed for locus went from H = 0.00 for the Las Cardas population to 0.114 in the Lautaro locality, with a global average of 5.2%. The genetic similarity values gave an average of 0.875 (range 0.726-1.00). Accordingly, similarity values were possible to distinguish three groups: north, central and Osorno. The Osorno population differed from the central group in Est-1 and Est-2, yet the Osorno population is only 20 km from a population of the central group.

Alleles↗
PubMed1994

Characterization of human serum-resistant and serum-sensitive clones from a single Trypanosoma brucei gambiense parental clone.

A protocol was developed to select clones of Trypanosoma brucei gambiense having different levels of resistance to normal human serum. Human serum-resistant clones were selected from a single parental clone by continuous serum treatment of infected immunosuppressed mice. Human serum-sensitive revertant clones were also obtained by continuous passage of resistant clones in immunosuppressed mice but without human serum pressure. It has been demonstrated that our trypanosome clones express distinct but stable levels of resistance. The variant antigenic type of each clone was characterized serologically and by 1-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis. After selective pressure with human serum, variant antigen-type differences always occurred among clones in which different human serum susceptibilities were found. The work reported here demonstrates that in our T. brucei gambiense immunosuppressed mouse model there is a predictable association between variant antigen type and human serum resistance.

Animals↗
PubMed1993

Relationship between human serum trypanocidal activity and host resistance to the African trypanosomes.

Results reported here show that humans have various levels of trypanocidal activity in their sera. This difference appeared stable when different samples were taken from the same individuals over time. It was not possible to account for the variability between individuals by obvious differences in health, nutrition, or living habits. In addition, the trypanocidal titers did not vary significantly when stored for various lengths of time at -70 C. To examine the relationship between the titer of trypanocidal activity in a host and the degree of human serum resistance of the challenge trypanosome inoculum, mice (C57BL/6J) were pretreated with various amounts of different human serum and then infected with clones having different degrees of resistance to human serum. It was demonstrated that host susceptibility to an African trypanosome infection depends upon 2 variables: the level of trypanocidal activity in individual human serum and the degree of human serum resistance of individual clones of African trypanosomes. Based upon the animal model presented here, it is hypothesized that this relationship is under selective evolutionary pressure and will influence the susceptibility of animals in endemic areas as well as the transmission of human trypanosomiasis.

Adolescent↗
PubMed1992

Intestinal parasites among North Carolina migrant farmworkers.

OBJECTIVES: The public health significance of intestinal parasitism among migrant farmworkers has been poorly defined. We report a three-part study in which we attempted to provide population-based estimates and identify risk factors for infection. METHODS: Parasite prevalence and incidence were estimated from two cross-sectional studies and a longitudinal study. We used questionnaires and clinical measurements such as hematocrits to examine risk factors and health effects. RESULTS: In the 1987 convenience sample (n = 265), parasite prevalence ranged from 28% among the US born to 86% among the Central American born, with no significant difference between the prevalence of pathogens among US-born (14%) and Mexican-born (24%) subjects (P = .12, chi 2 test). High prevalences were also found in the 1988 random sample. An annual incidence of 9.5% (n = 74) was demonstrated in 1988. Symptoms such as abdominal pain were associated with infection, and lower hematocrits were associated with hookworm infection (P = .02, t test). CONCLUSIONS: Infection with intestinal parasites appears to be an occupational hazard of farmwork, necessitating improved working and living conditions and greater clinical awareness.

Adolescent↗
PubMed1991

The Alton Dean pressure infusor: an evaluation.

An automatically pressurised infusor system, the Alton Dean infusor, has been compared with two types (cloth and plastic) of commonly used pneumatically pressurised bags. All the infusors had reasonably accurate pressure gauges but pressure could only be consistently maintained with the cloth infusors or with the Alton Dean infusors when connected to a compressed air supply. Sequential fast infusions were possible with all infusors, but simultaneous infusions could be limited in number when the pressure infusor was connected directly to pipeline gas. One of the Alton Dean pressure infusors tested had a leak in the pressurisation system, and the pressure adjustment valves were difficult to manipulate. These may require modification.

Evaluation Studies as Topic↗