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Biomedical subjects

J Salas

Publications and source records attributed to J Salas.

At least 19 recordsLinked to original sources
PubMed2005

Taurine and cholestasis associated to TPN. Experimental study in rabbit model.

Taurine seems to be essential in the newborn for bile acid (BA) tauroconjugation, and its deficiency has been implicated in total parenteral nutrition-associated cholestasis (TPN-AC). Our purpose was to study the relationship between taurine (Ta) and TPN-AC in rabbits, which have a similar biliary metabolism to that of humans. We used 40 young rabbits, fed for 10 days according to the following four groups: GA [10] given TPN, with amino acid solution (AA) but without taurine (Ta) or its AA-precursors (methionine, cysteine, and serine); GB [10] the same but only without taurine; GC [10] the same but with taurine and its precursors; and GD [10] the control group with oral nutrition and saline infusion. Complete blood and bile analytical data were obtained and analyzed, including plasma AA and BA. Liver samples were studied under optical and electron microscopy. Serum: In GC there was a 20% increase in the AA-precursors, but paradoxically it was greater in GA. Bile: In GC there was 30% more excretion of total and free BA compared with less than 20% in GA and GB. Regarding toxic BA, there was a 15% decline in GLC3S excretion, but more than 20% in LCA excretion, than in GA and GB. Moreover, in GC the glyco-/tauro-conjugate ratio was worse than in the other groups. Histomorphology: While in GA and GB liver steatosis was diffuse (microsteatohepatitis type), in GC there was macrosteatosis with mitochondria-surrounded lipid droplets. In GA and GB, the canaliculi appeared dilated, with abundant bile plugs and loss of microvilli. There are signs that taurine may protect against TPN-AC. The mechanism does not seem to be BA tauroconjugation, but probably taurine's antioxidant, membrane stabilization (with Ca2+ and HCO3-), and/or osmotic effects.

Amino Acids↗
PubMed2005

Performance of a new nebulizer system for simultaneous determination of Sb, Sn (hydride generation), V, and Zn by ICP-OES.

A new nebulizer system is described that extends the analytical capability of the inductively coupled plasma technique to include the simultaneous determination of two elements Sb and Sn (hydride-forming), with two conventional elements, V and Zn. The main advantage of this system is its simultaneous determination of elements that form volatile hydrides and elements that do not, without any instrumental changes. Optimization of reaction and instrumental conditions was performed to characterize the new system. The performance of the new nebulizer system was evaluated by studying the effect of some transition metals (Ni, Cu, Co, and Fe, 1-1000 mg L(-1)) on the Sb, Sn, V, and Zn emission signals (1 mg L(-1)). Interferences from transition metal ions were found to be insignificant for determination of the four elements in presence of L: -cysteine. Long-term and short-term stability was also evaluated. The precision, expressed as RSD for 15 replicate measurements was 0.7% for Sb, 1.7% for Sn, 2.5% for V, and 2.3% for Zn at 200 microg L(-1) of each analyte. The detection limits obtained were 0.52, 1.3, 3.2, and 4.7 microg L(-1) for Sb, Sn, V, and Zn, respectively. Spike and recovery experiments were performed on the NIST 1643c trace metals in water standard reference material and results were in agreement with the certified values.

Journal Article↗
PubMed2004

Groundwater chemistry of the Okélobondo uraninite deposit area (Oklo, Gabon): two-dimensional reactive transport modelling.

The stability of uranium-bearing minerals in natural environments is of interest to evaluate the feasibility of radioactive waste repositories. The uraninite bodies, UO2(s), in the Oklo district (Gabon) are the result of a natural fission process, which took place 1970 Ma ago. These deposits can be regarded as natural analogues for spent fuel. One of the uraninite bodies, the Okélobondo deposit, is located at a depth of 300 m. Groundwater samples from boreholes located at shallow depths (100-200 m) show neutral to basic pH, anoxic conditions (Eh = 0.10 to -0.05 V) and are saturated with respect to uraninite. In contrast, deeper samples collected in the vicinity of the ore body are oxidising (Eh = 0.32-0.47 V), slightly basic (pH = 7.0-8.5) and undersaturated with respect to uraninite. These oxidising conditions at depth, if present under repository conditions, may affect the stability of uranium oxide. In order to improve our understanding of the observed site geochemistry, the available information on the lithology and groundwater flow was integrated in a reactive transport model. The chemical composition and the pH-Eh values of the water sampled above and in the western side of the Okélobondo deposit can be explained by the interaction of meteoric recharge with pelites, dolomites and sandstones. The dissolution of Fe(II)-silicates and the oxidation of the Fe(II)-aqueous species maintained the pH-Eh distribution along the Fe(2+)-Fe(OH)3(am) equilibrium, with the result that uraninite does not dissolve. This may explain the lower uranium content in the water samples from pelites and dolomites above the Okélobondo deposit. The high Mn/Fe ratio and the high pH-Eh values of the water sampled at depth, close to the Okélobondo deposit, suggest a control by the Mn(2+)-MnOOH(s) equilibrium. This control is attributed to the dissolution of a large rhodochrosite, MnCO3(s), and manganite, MnOOH(s) deposit in the recharge area on the eastern side.

Geological Phenomena↗
PubMed2004

[Ring chromosome 20: a distinctive syndrome identifiable by electroclinical diagnosis].

The ring chromosome 20 syndrome is characterized by treatment resistant non-convulsive status epilepticus, and slow waves intercalated by spikes/spike waves predominantly in the front-temporal regions. Here, we describe the case of an 18 year old patient, whose seizures began at the age of 10, these being resistant to treatment. Neurologic examination and cranial MRI were normal. Interictal EEG showed normal background activity with burst of 2-20 seconds with bilateral spike wave. Ictal EEG showed continuous paroxysmal activity with generalized spike waves discharges and slow delta waves, coinciding with nonconvulsive status epilepticus. After 1 mg of intravenous clonazepam, both clinical semiology and EEG abnormalities disappeared. A cytogenetic study showed ring chromosome 20 in 35 % of metaphases. The epilepsy associated with ring chromosome 20 constitutes a syndrome with its distinctive electroclinical characteristics.

Adolescent↗
PubMed2003

[The stigma in the social representation of leprosy].

Social representation of leprosy in active patients under medical control is made up elements that come from the medical discourse and also from the discourse that about this disease circulates in society. This syncretism is expressed in each context a specific way on the components of the representation notion, beliefs, attitudes and behaviors - making of it a complex reality. On account of beliefs importance, whose depth and roots are linked to the thousand of years this disease has been known and to the seclusion practices in force till recent times, it would be comprehensible the predominance of elements related to common sense or popular knowledge. Nevertheless, as the representation is a collective construction, its fundamental features would be defined according to the specific characteristics of the group. To this respect, the main finding of this research referred to: first, the limited knowledge around this disease and the existence of beliefs and inadequated attitudes for controlling programs of active patients registered in the Maracaibo Service of Sanitary Dermatology located in Venezuela (Servicio de Dermatologia Sanitaria de Maracaibo (SDSMJ, Venezuela); second, a predominance of a congnitive dimension of representation, notions and beliefs relate to the role of fortune and fate, sexual promiscuity or heritage in the contagion; third, a patient's tendency to reproduce a disqualified stereotype and hide the disease due to an exaggerated rejection fear.

English Abstract↗
PubMed2002

Evaluation of select variables in the ion chromatographic determination of F-, Cl-, Br-, NO(-)3, SO(-2)4, and PO(-3)4 in serum samples.

A full experimental design at two levels is applied for the estimation of the significance of select factors that may influence the ion chromatography (IC) determination of F-, Cl-, Br-, NO(-)3, SO(-2)4, and PO(-3)4 in serum samples. The factors studied are various sample deproteinization procedures, eluent composition, and flow rates. Deproteinization using either acetonitrile-NaOH or ultrafiltration can be used in order to obtain a significant protein removal before IC analysis; however, the former is recommended because it is less time-consuming and cheaper. Better resolution is obtained when a sodium hydroxide solution is used as the eluent. There is no influence of the sample's deproteinization procedures on the chromatographic resolution.

Anions↗
PubMed2002

[Left paramesocolic hernia with retroperitoneal incarceration of jejunum].

We present a case left paramesocolic hernia and review the literature. The patients was a 14 years old male and had suffered periods of relapses into abdominal pain from the age of three. When for years old he was operated on using the Nisses technique. Also a laparoscopy had already been performed on this same patient when he was 13 years old, without discovering any pathological conditions. In a new upper gastrointestinal serie, realized one year later, a retroperitoneal incarceration and a paraduodenal loop of jejunum was observed, which obstructed, partially the second part of the duodenum. We have not found the anatomical characteristics of this case in any previous report. In the ample literature pressured, it was confirmed that almost all the clinical cases, previously published had suffered a relapse abdominal pain crisis, diagnosed in advanced states and in/or emergency situations. This produces a mortality rate higher than 20% and or irreparable digestive damage. In cases involving paraduodenal hernias, there exists a low rate of diagnostic suspicion. These delays and diagnostic errors cause irreparable damage. In those patients who suffer relapses into abdominal pain syndrome, one should always include the differential diagnosis of PMH, applying a complete gastrointestinal serie or a CT-Scan with contrast.

Abdomen, Acute↗
PubMed2001

Novel azo derivatives as prodrugs of 5-aminosalicylic acid and amino derivatives with potent platelet activating factor antagonist activity.

This paper describes the synthesis of a series of azo compounds able to deliver 5-aminosalicylic acid (5-ASA) and a potent platelet activating factor (PAF) antagonist in a colon-specific manner for the purpose of treating ulcerative colitis. We found it possible to add an amino group on the aromatic moiety of our reported 1-[(1-acyl-4-piperidyl)methyl]-1H-2-methylimidazo[4,5-c]pyridine derivatives or on British Biotech compounds BB-882 and BB-823 maintaining a high level of activity as PAF antagonist. A selected compound UR-12715 (49c) showed an IC(50) of 8 nM in the in vitro PAF-induced aggregation assay, and an ID(50) of 29 microg/kg in the in vivo PAF-induced hypotension test in normotensive rats. Through attachment of 49c to the 5-ASA via azo functionality we obtained UR-12746 (70). Pharmacokinetics experiments with [14C]-70 allow us to reach the following conclusions, critical in the design of these new prodrugs of 5-ASA. Neither the whole molecule 70 nor the carrier 49c were absorbed after oral administration of [14C]-70 in rat as was demonstrated by the absence of plasma levels of radioactivity and the high recovery of it in feces. Effective cleavage of azo bond (84%) by microflora in the colon is achieved. These facts ensure high topical concentrations of 5-ASA and 49c in the colon. Additionally, 70 exhibited a potent anticolitic effect in the trinitrobenzenesulfonic acid-induced colitis model in the rat. This profile suggests that UR-12746 (70) provides an attractive new approach to the treatment of ulcerative colitis.

Amines↗
PubMed2001

Exact T=0 partition functions for Potts antiferromagnets on sections of the simple cubic lattice.

We present exact solutions for the zero-temperature partition function of the q-state Potts antiferromagnet (equivalently, the chromatic polynomial P) on tube sections of the simple cubic lattice of fixed transverse size Lx x L(y) and arbitrarily great length L(z), for sizes Lx x L(y)=2 x 3 and 2 x 4 and boundary conditions (a) (FBC(x),FBC(y),FBC(z)) and (b) (PBC(x),FBC(y),FBC(z)), where FBC (PBC) denote free (periodic) boundary conditions. In the limit of infinite length, L(z)-->infinity, we calculate the resultant ground-state degeneracy per site W (=exponent of the ground-state entropy). Generalizing q from Z+ to C, we determine the analytic structure of W and the related singular locus Beta which is the continuous accumulation set of zeros of the chromatic polynomial. For the L(z)-->infinity limit of a given family of lattice sections, W is analytic for real q down to a value q(c). We determine the values of q(c) for the lattice sections considered and address the question of the value of q(c) for a d-dimensional Cartesian lattice. Analogous results are presented for a tube of arbitrarily great length whose transverse cross section is formed from the complete bipartite graph K(m,m).

Journal Article↗
PubMed2000

DARPP-32 and CREB are present in type 2 iodothyronine deiodinase-producing tanycytes: implications for the regulation of type 2 deiodinase activity.

Type 2 iodothyronine deiodinase, an enzyme involved in the conversion of thyroxin to the biologically active 3,5, 3'-triiodothyronine, is highly concentrated in a group of specialized ependymal cells, tanycytes, lining the wall and floor of the third ventricle. As this distribution is highly reminiscent of the distribution of cells containing the phosphatase inhibitor, DARPP-32, we raised the possibility that these two proteins may coexist in tanycytes and that DARPP-32 may modulate type 2 deiodinase activity by regulating the phosphorylation state of the cAMP regulatory factor, CREB. To address this question, double-labeling histochemical studies were performed for type 2 deiodinase mRNA and DARPP-32 immunoreactivity (IR), or DARPP-32- and CREB-IR in the same tissue sections. Type 2 deiodinase mRNA was found in the cell bodies of all DARPP-32-immunolabeled tanycytes. Both type 2 deiodinase mRNA and DARPP-32-IR also extended into tanycyte processes that ramified in the arcuate nucleus and median eminence, in close association with blood vessels and portal capillaries. In contrast, type 2 deiodinase mRNA was not present in the same cells that contained DARPP-32-IR in the pituitary gland. All tanycytes containing DARPP-32-IR also contained CREB-IR in their nucleus. Since type 2 deiodinase activity can be induced by substances that increase cAMP, we hypothesize that DARPP-32 may regulate the activity of type 2 deiodinase by prolonging the activation of CREB. Selectivity for the colocalization of these factors to tanycytes but not the pituitary gland, may explain the heterogeneous response of type 2 deiodinase activity in these two loci in response to specific stimuli such as fasting.

Animals↗
PubMed2000

Isolation and partial characterization of three DNA polymerases from Trypanosoma cruzi.

Three distinct DNA polymerase fractions (A, B and C), were isolated from Trypanosoma cruzi epimastigote forms. Fraction A is a low molecular mass enzyme corresponding to beta-like DNA polymerase of T. cruzi. Fraction B co-purified along several purification steps with fraction A, but in the last step it was clearly separated by a phosphocellulose chromatography. Fraction C was separated from fractions A and B by binding to DEAE-cellulose column, since the other two fractions were eluted in the flowthrough. This enzyme has an apparent native molecular mass of 100 kDa and showed a high preference for poly(dC)-oligo(dG) among different template-primers tested as substrate. Western-blot and biochemical analysis strongly suggest that the three DNA polymerase fractions correspond to different molecular entities. These results are in agreement with the idea that fraction C is a new DNA polymerase of T. cruzi, not described before.

Animals↗
PubMed1999

[The diet rich in monounsaturated fat modifies in a beneficial way carbohydrate metabolism and arterial pressure].

OBJECTIVE: Two dietary regimens recommended for the reduction of coronary risk, by way of their effects on lipid profile, are the diet low in saturated fat and a diet rich in monounsaturated fats (MUFA). However the effects of these diets on carbohydrate metabolism in healthy subjects are not well known. The objective of this study was to compare the effect of both diets on various parameters of carbohydrate metabolism. METHODS: 41 healthy young males were submitted to 3 consecutive diets, each for a duration of 4 weeks. The first diet was rich in saturated fat (SAT) (38% fat, 20% saturated). The second was rich in carbohydrates following the recommendations of the NCEP-I (National Cholesterol Education Program type I) (28% fat, 47% carbohydrates). The last one was a diet rich in monounsaturated fatty acids (38% fat, 22% MUFA). At the end of each dietary period, blood pressure (BP) and blood levels of glucose, insulin and free fatty acids were determined. 29 subjects were also submitted to an oral glucose tolerance test (OGTT) at the end of each diet. RESULTS: The SAT diet induced the highest levels of insulin after the OGTT. The consumption of the MUFA diet determined the lowest levels of fasting blood glucose (-0.60 mmol/l [13%], p < 0.0002), insulin (-9 microUl/ml [47%], p < 0.0002) and free fatty acids (-0.11 mmol/l [24%], p = 0.006), compared to the NCEP-I diet. Systolic and diastolic blood pressure were higher in the NCEP-I diet than during the other periods (SBP: +6 mmHg compare with SAT [5%], p = 0.0001; and +5 mmHg compare with MUFA [4%], p = 0.0001; DBP: +20 mmHg compare with MUFA [27%], p = 0.0001) and +6 mmHg compared with SAT [8%], p = 0.0001). CONCLUSION: Of the diets most commonly used for the treatment and prevention of arteriosclerosis, a diet rich in monounsaturated fats is the most beneficial for the healthy population from the point of view of carbohydrate metabolism and blood pressure.

Adult↗
PubMed1999

Replication of African swine fever virus DNA in infected cells.

We have examined the ultrastructural localization of African swine fever virus DNA in thin-sections of infected cells by in situ hybridization and autoradiography. Virus-specific DNA sequences were found in the nucleus of infected Vero cells at early times in the synthesis of the viral DNA, forming dense foci localized in proximity to the nuclear membrane. At later times, the viral DNA was found exclusively in the cytoplasm. Electron microscopic autoradiography of African swine fever virus-infected macrophages showed that the nucleus is also a site of viral DNA replication at early times. These results provide further evidence of the existence of nuclear and cytoplasmic stages in the synthesis of African swine fever virus DNA. On the other hand, alkaline sucrose sedimentation analysis of the replicative intermediates synthesized in the nucleus and cytoplasm of infected macrophages showed that small DNA fragments ( approximately 6-12S) were synthesized in the nucleus at an early time, whereas at later times, larger fragments of approximately 37-49S were labeled in the cytoplasm. Pulse-chase experiments demonstrated that these fragments are precursors of the mature cross-linked viral DNA. The formation of dimeric concatemers, which are predominantly head-to-head linked, was observed by pulsed-field electrophoresis and restriction enzyme analysis at intermediate and late times in the replication of African swine fever virus DNA. Our findings suggest that the replication of African swine fever virus DNA proceeds by a de novo start mechanism with the synthesis of small DNA fragments, which are then converted into larger size molecules. Ligation or further elongation of these molecules would originate a two-unit concatemer with dimeric ends that could be resolved to generate the genomic DNA by site-specific nicking, rearrangement, and ligation as has been proposed in the de novo start model of Baroudy et al. (B. M. Baroudy, S. Venkatesam, and B. Moss, 1982, Cold Spring Harbor Symp. Quant. Biol. 47, 723-729) for the replication of vaccinia virus DNA.

African Swine Fever Virus↗
PubMed1999

[Clear cell renal carcinoma outside of the usual age group].

We report a case of a 17 year old woman with a clear cell sarcoma of kidney treated at the Division of Urology of Hospital General de Agudos Dr. José M. Ramos Mejía dependent of Government of Buenos Aires City. This report is based on the unusual age of tumor presentation and its good course and results after radiotherapy and chemotherapy, with 10 years survival after surgery.

Adolescent↗