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Biomedical subjects

A Varela

Publications and source records attributed to A Varela.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Study of pulmonary lesions with (99m)Tc-Tetrafosmin and chest spect. Determination of uptake related factors, diagnostic value and prognosis].

One hundred fifteen patients with 119 pulmonary lesions in which malignancy was suspected underwent a SPECT study with 99mTc-Tetrofosmin (TTF) to assess the possible factors involved in the uptake of the radiopharmaceutical. The TTF uptake rate in the lung tumor with respect to that of healthy tissue (TTF index) was evaluated in terms of: benignity and malignancy, histological type, stage, cell differentiation, size, necrosis, survival and the influence of P-glycoprotein (Pgp), detected by immunohistochemistry, on the TTF uptake. The mean TTF index in the 18 benign lesions studied was 1.01 0.05, while that of the 101 malignant lesions was 1.59 0.45 (p < 0.001), with a positive predictive value of 97.7% and a negative predictive value of 50%. The comparison of the histological types, degree of cell differentiation, necrosis and stage revealed no statistically significant differences. With respect to size, those tumors measuring > 3 cm showed greater uptake than smaller lesions. In patients with non-small cell lung cancer, a positive relationship was observed between the TTF index and survival, a circumstance that did not occur in patients with small cell lung cancer. In the cases in which the presence of Pgp was assessed, there was an inverse relationship between the TTF ratio and Pgp expression. In conclusion, thoracic SPECT with 99mTc-TTF has a high positive predictive value for the presence of lung cancer, although a negative study does not rule out the existence of the disease. The reason for this is the inverse relationship between 99mTc-TTF uptake and the density of Pgp expression.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

Transition from the layered Sr2RhO4 to the monodimensional Sr4RhO6 phase.

Study of the structural changes occurring during the reduction process of the Sr2RhO4+delta, (214), n=1 term of the Ruddlesden and Popper series, shows that for delta <0.02 values, this material dissociates into the Sr4RhO6 (416) monodimensional phase, alpha = infinity, beta = 0 compound of the (A3B2O6)alpha-(A3B3O9)beta family, and Rh metal. During the first stage, this process occurs by the formation of an intergrowth between the (214) and (416) materials which can be only detected by high resolution electron microscopy and is easily interpreted on the basis of the structural relationship established between them. Further reduction allows the segregation of both phases as separated entities, which coexist with Rh metal. The dissociation process is reversible and, under oxidizing conditions, a layered material with anionic composition delta =0.06 is always obtained. This behaviour seems to be a general way of accommodating the compositional changes in layered A2BO4 phases where the B cation is always in a octahedral environment. The structural mechanism of this transformation is proposed, and the structural relationship between these two low-dimensional oxides is established.

Journal Article↗
PubMed2001

Strengthening user participation through health sector reform in Colombia: a study of institutional change and social representation.

The challenge of achieving community participation as a component of health sector reform is especially great in low- and middle-income countries where there is limited experience of community participation in social policy making. This paper concentrates on the social representations of different actors at different levels of the health care system in Colombia that may hinder or enable effective implementation of the participatory policy. The study took place in Cali, Colombia and focused on two institutional mechanisms created by the state to channel citizen participation into the health sector, i.e. user associations and customer service offices. This is a case study with multiple sources of evidence using a combination of quantitative and qualitative social science methods. The analysis of respondents' representations revealed a range of practical concerns and considerable degree of scepticism among public and private sector institutions, consumer groups and individual citizens about user participation. Although participation in Colombia has been introduced on political, managerial and ethical grounds, this study has found that health care users do not yet have a meaningful seat around the table of decision-making bodies.

Attitude to Health↗
PubMed2001

Antisense inhibition of brain renin-angiotensin system decreased blood pressure in chronic 2-kidney, 1 clip hypertensive rats.

The systemic renin-angiotensin system (RAS) plays an important role in blood pressure (BP) regulation during the development of 2-kidney, 1 clip (2K1C) hypertension. Its contributions decrease with time after constriction of the renal artery. During the chronic phase, the peripheral RAS returns to normal, but the hypertension is sustained for months. We hypothesized that in this phase the brain RAS contributes to the maintenance of high BP. To test the hypothesis, we studied the role of brain RAS by decreasing the synthesis of angiotensinogen (AGT) and the angiotensin II (Ang II) type 1a receptor (AT(1)R) with intracerebroventricular injections of antisense oligonucleotides (AS-ODNs). The response of systolic BP (SBP) to AS-ODNs to AGT mRNA was studied in 2K1C rats at 6 months after clipping, and the response to AS-ODNs to AT(1)R mRNA was studied at 10 months after clipping. Intracerebroventricular injection of AS-ODN-AGT (200 microgram/kg, n=5) significantly decreased SBP (-22+/-6 mm Hg, P<0.05) compared with the sense ODN (n=5) and saline (n=3) groups. Intracerebroventricular injection of AS-ODN-AGT reduced the elevated hypothalamic Ang II level. The hypothalamic Ang II content in sense ODN and saline groups was significantly (P<0.05) higher than in the nonclipped group. Compared with inverted ODN, intracerebroventricular injection of AS-ODN-AT(1)R (250 microgram/kg, n=6) significantly decreased SBP (-26+/-8 mm Hg, P<0.05) for 3 days after injection. This was a brain effect because intravenous AS-ODN-AT(1)R at a dose of 250 to 500 microgram/kg did not affect SBP. These results suggest that the brain RAS plays an important role in maintaining the elevated SBP in chronic 2K1C hypertension.

Angiotensin II↗
PubMed2001

Presence of encysted immature nematodes in a released whooping crane (Grus americana).

Numerous nematode cysts were observed throughout the mesentery and on the surface of gastrointestinal organs in a whooping crane (Grus americana) that was found dead in a central Florida marsh. Morphology of the excysted nematodes most closely resembled third-stage larvae in the order Spirurida but were not similar to any species previously reported in whooping cranes. Evidence presented suggests that the larvae may be Physocephalus sexalatus, a swine spirurid in the subfamily Ascaropsinae that is commonly found encapsulated in birds, amphibians, and reptiles. We suspect that the whooping crane may potentially serve as a transport host for this parasite.

Animals↗
PubMed2000

Association of HLA-DRB1*1602 and DRB1*1001 with Takayasu arteritis in Colombian mestizos as markers of Amerindian ancestry.

We performed HLA Class I and Class II typing in 16 patients (15 women, one man) with a confirmed diagnosis of Takayasu arteritis. We did not find any of the previously described associations with HLA-B52, and/or HLA-DRB1*1301 alleles. However, in our patients, HLA-DRB1*1602 and HLA-DRB1*1001 were significantly increased. The association of Takayasu arteritis with Amerindian and Asian HLA-DRB1 alleles (DRB1*1602 and DRB1*1001) in the Colombian mestizo patients reported here, and with HLA-B*3906 previously reported in Mexicans, suggest the possibility that some HLA and disease associations are markers for ethnicity of a population carrying a disease gene which is present in an admixed population with the disease.

Adolescent↗
PubMed2000

Effects of hypoxic preconditioning on the hypoxic-reoxygenated atria from fed and fasted rats.

Hypoxic preconditioning (PC) was studied using rat atria set up isometrically in 10 mM dextrose medium and paced at 1 Hz, applying three different protocols wherein fed and 24-h fasted rats were used in protocols 1 and 2 and only the fed in protocol 3. In protocol 1, PC was achieved applying a 5 min hypoxia followed by 10 min of reoxygenation before the onset of a 60 min hypoxia and 60 min reoxygenation. In protocol 2 the 5 min and a posterior 45 min hypoxia were applied in the absence of dextrose whereas in the 10 min and 60 min reoxygenation periods dextrose was present. In protocol 3, two cycles of 5 min dextrose-free hypoxic periods were applied before the sustained hypoxia (dextrose-free) and reoxygenation periods (10 min and final 45 min, both in the presence of dextrose). In the control groups of all protocols, the equilibration periods were prolonged to compensate the duration of PC. In the control groups of protocols 1 and 2, the sustained hypoxia evoked greater disturbances of contractility and a smaller post-hypoxic recovery in the fasted than in the fed rat atria. In protocol 1, PC markedly reduced the rise in resting tension and improved the post-hypoxic recovery in the fasted rat atria whereas in the fed rat atria protective effects were small and brief. In protocol 2, PC evoked a small reduction of contracture only in the atria from fasted rats and in protocol 3, PC exacerbated the hypoxic disturbances. These data suggest that PC effects depend both on the severity of the PC stress and the sustained hypoxia; and that PC does not require coronary flow.

Animals↗
PubMed2000

A deletion on chromosome 4 cosegregates with the whirler deafness mutation: exclusion of Orm1 as a candidate.

Whirler (wi) mice display profound deafness and a head-tossing and circling phenotype, showing an autosomal recessive mode of inheritance. The wi mutation has been shown to map close to the Orm gene cluster on mouse Chromosome (Chr) 4. We have, therefore, investigated the Orm loci as candidates for the whirler gene. Detailed mapping and analysis of the Orm gene cluster in both normal and whirler mice indicates the presence of a <48-kb deletion in whirler mice that disrupts the Orm1 locus. The Orm1 locus is also deleted in the CE/J mouse strain, and we discuss the candidature of Orm1 for the whirler gene.

Animals↗
PubMed1999

Genetic mapping of the whirler mutation.

The whirler (wi) mutation on mouse Chromosome (Chr) 4 results in an autosomal recessive neuroepithelial deafness and vestibular dysfunction exhibited as a characteristic shaker-waltzer behavior (deafness, circling, and head-bobbing). We have constructed a genetic linkage map across the wi region in both an interspecific [(wi/wi x CAST/Ei)F1 x wi/wi] backcross (n = 817) and an intraspecific [(wi/wi x CBA/Ca)F1 x wi/wi)] backcross (n = 335). In the interspecific backcross, wi was found to be non-recombinant with Orm1, 0.12 cM distal of D4Mit87 and Ambp, and 0.12 cM proximal of CD301. In the intraspecific backcross, wi was found to be non-recombinant with Orm1 and D4Mit244, 0.3 cM distal of Mup1, and 0.6 cM proximal of Tnc. We also report a family from the interspecific backcross that shows evidence of multiple recombinations across the region of mouse Chr 4 around the wi locus. These rearrangements appear specific to both the region and the family.

Animals↗
PubMed1999

Pulmonary hydatidosis: surgical treatment and follow-up of 240 cases.

OBJECTIVE: We review a series of 240 patients treated surgically for pulmonary hydatid cyst in our center between 1966 and 1988, assessing the results with our surgical technique, which involves a novel needle aspiration device designed by Professor D. Figuera, and postoperative treatment protocol. PATIENTS AND METHODS: The majority (60.4%) of the patients were from areas endemic for hydatid disease. The mean age of the patients at the time of the surgical procedure was 31.5 +/- 7.2 years (range: 4-70 years). A trocar-suction device was used for the needle aspiration of 276 (92%) of the 300 cysts encountered in the 240 patients. The remaining 24 cysts were removed integrally by means of different surgical techniques such as cyst enucleation, lobectomy, segmentectomy and atypical pulmonary resection. The residual cavity was treated by pericystectomy and eversion to the pleural surface in 238 cases (86.2%) and by capitonnage in 38 (13.7%). High vacuum suction (-30 cm H2O) was employed in every case. Depending on when the procedure was performed, the patients were treated with mebendazole or albendazole according to the protocol designed by Bekhti. RESULTS: Clinical assessment of the symptoms and plain chest X-ray led to the correct diagnosis in 228 cases (95%). In six (2.5%), imaging studies such as ultrasonography, computed tomography and nuclear magnetic resonance were required, and in the remaining six cases (2.5%), the diagnosis was established intraoperatively or in the subsequent histopathological study. One hundred and seventy patients (70.8%) presented a solitary lung cyst, while the remaining 70 (29.2%) were found to have multiple cysts in one or more lobes of one or both lungs. In addition, 45 patients (18.7%) presented hepatic cysts and 25 (10.4%) had cysts in other locations. After 18 years of follow-up, the survival rate was 94.6%. Of the surviving patients, 98.3% were free of pulmonary hydatid disease and 95.1% were free of hydatid disease. CONCLUSIONS: The trocar-suction device employed here for needle aspiration of hydatid cysts has demonstrated its efficacy in preventing the rupture of the cyst and its possible dissemination. With its use, the parasite is eradicated and the residual cavity can be excised.

Adolescent↗
PubMed1999

Effects of pentanoate, 4-pentenoate, 3-hydroxybutyrate and insulin on the tissue-levels of long-chain acyl CoA and acylcarnitine in the oxygenated and hypoxic rat atria.

Under hypoxic conditions the atrial contents of long-chain acyl CoA (LCCoA) and long-chain acylcarnitine display a close correlation with the noxious effects of fasting on the atrial functions as well as with the amelioration effected by inhibitors of carnitine palmitoyltransferase I. These findings suggested that fatty acid oxidation was detrimental for the hypoxic atria. However, since changes of the LCCoA and LCCa levels which may occur together with the hypoxic disturbances attained under some other metabolic interventions had not been assessed yet, present investigation aimed to provide information about this issue. At the end of the prehypoxic equilibration period, all the treatments tested evoked a fall of the free-CoA levels whereas free-carnitine, LCCoA and LCCa remained unchanged. In the hypoxic atria, 4-pentenoate, an inhibitor of fatty acid beta-oxidation that also can be oxidized, did not change LCCoA and LCCa levels whereas the readily oxidizable pentanoate evoked a drop of LCCoA. These effects may be due to the trapping of CoA as the short-chain acyl esters of both substances. Since 4-pentenoate and pentanoate were noxious on the hypoxic atria even though they did not increase LCCoA and LCCa contents, it may be inferred that short-chain acyl esters might be deleterious during oxygen shortage. The exposure to 3-hydroxybutyrate, an oxidizable substrate whose availability increases during fasting, did not alter the LCCoA and LCCa contents, agreeing with the weak detrimental effects that it exerts on the hypoxic atria. On the other hand, insulin elicited a rise in the LCCoA and a fall in the LCCa contents. Inasmuch insulin had been shown to improve the performance of the hypoxic atria, these findings suggest that LCCoA might not be involved in the noxious effects of fatty acid oxidation whereas LCCa would be the major toxic catabolite.

3-Hydroxybutyric Acid↗