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Biomedical subjects

D Vargas

Publications and source records attributed to D Vargas.

16 recordsLinked to original sources
PubMed2000

S-adenosylmethionine and Pneumocystis carinii.

We previously reported that S-adenosylmethionine (AdoMet), a key molecule in methylation reactions and polyamine biosynthesis, enhances axenic culture of the AIDS-associated opportunistic fungal pathogen Pneumocystis carinii. Here we report that AdoMet is absolutely required for continuous growth. Two transporters are present, one high affinity, K(m) = 4.5 microm, and one low affinity, K(m) = 333 microm. The physiologically relevant high affinity transporter has a pH optimum of 7.5 and no related natural compounds compete for uptake. Transport is 98% inhibited at 4 degrees C, 24% inhibited by 20 mm sodium azide, and 95% inhibited by the combination of 20 mm sodium azide and 1 mm salicylhydroxamic acid; thus transport is active and dependent on both a cytochrome chain and an alternative oxidase. In vitro, AdoMet is used at a rate of 1. 40 x 10(7) molecules cell(-1) min(-1). AdoMet synthetase activity was not detected by a sensitive radiolabel incorporation assay capable of detecting 0.1% of the activity in rat liver. In addition, the AdoMet plasma concentration of rats is inversely correlated with the number of P. carinii in the lungs. These findings demonstrate that P. carinii is an AdoMet auxotroph. The uptake and metabolism of this compound are rational chemotherapeutic targets.

Animals↗
PubMed2000

[Echinococcosis/hydatidosis in the VII Region of Chile: diagnosis and educational intervention].

This study was designed to embrace three areas: a) serologic and radiologic diagnosis and surgical treatment of hydatidosis in an asymptomatic human population, b) animal diagnosis and the treatment of dogs, and c) evaluation of extent of knowledge and performance of educational interventions among rural families and health, livestock, and education professionals and technicians, in order to help control the disease transmission cycle. Indirect hemagglutination and ELISA tests were performed on 5,556 apparently healthy people. Of these, 42 (0.8%) had positive results on both tests, for a seroprevalence of 754.6 per 100,000. These 42 subjects were scheduled for liver ultrasonography and a chest x-ray; of the 26 who complied, 16 showed images compatible with a hydatid cyst. Those 16 cases were sent to the hospital for surgery. In 9 of the cases the diagnosis was confirmed surgically, for a prevalence of 161.7 per 100,000. Arecoline hydrobromide was administered as a laxative to 2,358 dogs to detect the strobilar form of Echinococcus granulosus, and positive results were found in 11% of the dogs. Official data for slaughterhouses indicated the presence of hydatid cysts in 13% of the cattle, 4.4% of the sleep, and 4.2% of the pigs slaughtered in the region. The educational program included an evaluation of the extent of knowledge by surveying heads of household; an educational intervention among families through an informal active participatory process using educational games, in which 1,082 families participated; and an educational intervention with professionals and technicians using distance and in-person approaches. To evaluate the program, the results of knowledge tests before and after educational interventions with 200 families (cases) were compared with those from 95 families who did not participate (controls). Of the 1,423 heads of household initially surveyed about their knowledge of echinococcosis/hydatidosis, 783 of them (55%) said they knew nothing about the infection. It was found that the participatory educational games were well adapted to the lifestyle of people from rural areas and made change possible. Training was provided to 276 health professionals, 201 technical assistants, and 453 rural teachers. The program reached 100% of the staff members of the area's rural primary health care services.

Animals↗
PubMed1998

Leptin in relation to resumption of menses in women with anorexia nervosa.

Serum levels of leptin are decreased in underweight AN patients and increase with weight restoration. To assess the relationship of decreased leptin levels with other hormonal abnormalities in AN and to evaluate the possible role of increasing leptin levels, alone or in combination with other hormones, in the resumption of menses that accompanies weight gain, we studied cross-sectionally sixty-five consecutively enrolled AN patients. Subjects were divided in three groups: (I) underweight and amenorrheic; (II) weight-recovered but still amenorrheic; and (III) weight-recovered and eumenorrheic women. Patients in group I had decreased BMI, serum leptin, estradiol (E2), insulin-like growth factor 1 (IGF-1) and urinary growth hormone (GH) levels and increased sex hormone-binding globulin (SHBG) levels, compared to AN patients in groups II and III. Moreover, although no differences in leptin levels or BMI were observed between amenorrheic and eumenorrheic weight-recovered patients (groups II and III), free E2 and GH levels were higher (P<0.02) in weight-recovered, eumenorrheic women. Thus, it appears that leptin is a necessary, but not a sufficient, factor for the resumption of menses in AN patients.

Adult↗
PubMed1995

Diterpenes from Solidago rugosa.

Investigation of the roots and aerial parts of Solidago rugosa afforded the known diterpenes kolavenol, hardwickiic acid, (-)-kaur-16-en-19-oic acid, (+)-manool, (+)-3 beta-hydroxymanool, manoyl oxide and ent-abietic acid. In addition, the new labdane diterpene (+)-18-tigloyloxymanool and four new ent-abietanes were obtained. The structures of all known and new compounds were elucidated by spectroscopic methods, especially high-field 1H and 13C NMR, and inverse 1H-13C-correlation techniques, as well as chemical transformations. Six diterpenes were tested against Mycobacterium tuberculosis and M. avium, but showed no significant activities with minimum inhibitory concentrations of > 100 micrograms ml-1.

Diterpenes↗
PubMed1995

[Patients with chronic airflow limitation: effects of the inspiratory muscle training with threshold load valve, built with appropriate technology, associated to nutritional support].

AIM: To assess prospectively the effects of a controlled program of inspiratory muscle training program and nutritional support in patients with chronic obstructive lung disease (COPD). PATIENTS AND METHODS: Twenty-three patients with COPD were randomly assigned into four groups. Group I received a 1000 kcal/day nutritional supplement, given as a casein based enteral nutritional formula; group III was subjected to inspiratory muscle training, using an inexpensive pressure threshold load valve constructed according to the Appropriate Technology principles of the WHO, adjusted at 30% of Maximal Inspiratory Mouth Pressure and received also the nutritional supplement; group IV was trained but did not receive the nutritional supplement and group II was not trained nor supplemented. Patients were studied during three months and monthly, inspiratory muscle function, exercise capacity and anthropometry were measured. RESULTS: A significant improvement in exercise capacity, maximal inspiratory pressure and inspiratory muscle endurance was observed in the four groups throughout the study. Trained subjects had greater improvement in their inspiratory muscle endurance, compared to untrained subjects. Nutritional support had no effect in inspiratory muscle function or exercise capacity. No changes in anthropometric measures were observed. CONCLUSIONS: The pressure threshold load valve used in this study, improved inspiratory muscle endurance and nutritional support had no effect in patients with COPD.

Aged↗
PubMed1994

Conformations and structure studies of sugar lactones. Part III. The composition and conformation of D-mannurono-gamma-lactone in solution, and the structural analysis of its beta anomer in the solid state.

Complete analyses of the proton and carbon chemical-shift assignments of D-mannurono-gamma-lactone (1) have been achieved by 1D and 2D NMR spectral measurements. At equilibrium, the anomeric alpha and beta forms were present in the ratio of 34:66 in D2O and 72:28 in Me2SO-d6. The solution data indicated that the dienvelope conformation 2E:E4 to be the favored conformation of 1 in solution. The crystal structure of 1 was determined, and it showed that the crystalline form is the beta anomer, a bicyclic structure, consisting of fused five-membered furanose and lactone rings, in agreement with an earlier deduction from chemical evidence. In contrast to the solution conformation, the furanose ring adopts a twist conformation lying between the 2(1)T and 1E conformations with phase angle (P) and pseudorotation amplitude (tau m) of -44.23 degrees and 37.9 degrees, respectively, whereas the lactone ring adopts an envelope E5 conformation slightly distorted towards 6T5 with a phase angle (P) of -22.3 degrees and a pseudorotation amplitude (tau m) of 18.4 degrees. The molecules are linked in the crystal through a hydrogen-bonding network that involves all hydroxyl groups as well as the ring oxygen atoms.

Carbohydrate Conformation↗
PubMed1993

Cyclooxygenase and lipoxygenase arachidonate metabolites synthesized by mouse peritoneal macrophages: in vitro effect of N-phenyllinoleamide from toxic oil samples.

N-phenyllinoleamide (NPLA) has been detected as extraneous compound in adulterated cooking oils associated with a unique epidemic disease known as the Toxic Oil Syndrome (TOS). In this communication we report on the action of NPLA on the endogenous cyclooxygenase and lipoxygenase arachidonate metabolism. Results show that mouse peritoneal macrophages (MPM) exposed to 1 mM NPLA for 2 h undergo significant increases of 6-keto prostaglandin F1a, prostaglandin E2, leukotriene B4, 12- and 15-hydroxyeicosatetraenoic acids. MPM prelabelled with 3H-AA showed an enhanced release when exposed to NPLA. Thus, it is concluded that NPLA potentiates AA release from cell membrane phospholipids and the subsequent cyclooxygenase and lipoxygenase oxidative metabolism of this precursor to various eicosanoids. This is in agreement with the implication of peroxidative process mediated by fatty acids anilides in TOS.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1993

Biomimetic transformations of parthenolide.

An investigation of BF3-mediated rearrangements of parthenolide [1] provided micheliolide [5] as a major product. Minor reaction products included 10 (14)-dehydro-5 alpha-hydroxy-trans-guaianolide [2], 9,10-dehydro-5 alpha-hydroxy-trans-guaianolide [3], the xanthanolide 2-desoxy-6-epi-parthemollin [4], 1,2-dehydro-4 alpha-hydroxyguaianolide [6], 11,13-dehydrocompressanolide [7], and bicyclo[6.2.0]dec-10(14)-en-12,6-olide [8]. Their mechanisms of formation were interpreted as rearrangements involving carbocation intermediates.

Cyclization↗
PubMed1992

Synthesis and X-ray crystal and solution structures of 2,5-anhydro-3,4-O-(1,2-ethanediyl)-D-mannitol: a locked 4T3 furanose conformer.

2,5-Anhydro-3,4-O-(1,2-ethanediyl)-D-mannitol (1) was prepared from 2,5-anhydro-D-mannitol (2) in three steps. The fused ring system was introduced by a phase-transfer alkylation using 1,2-dibromoethane. Its conformation in solution was determined by NMR studies at 500 MHz. Variable-temperature studies showed no lineshape change from 25 to 80 degrees in D2O. The data indicate that the five-membered ring is locked by the trans-fused six-membered 1,4-dioxane ring into a twist 4T3 conformation. A single-crystal X-ray study was carried out. The crystals are orthorhombic, C222(1), a = 4.7252 (6), b = 14.0364 (12), c = 13.268 (2) A, Z = 4, with R = 0.032 for 894 observations. The molecule lies upon a crystallographic two-fold axis, and thus the five-membered ring exists in a perfect 4T3 conformation with a pseudorotation angle of 0 degree and amplitude of 47.2 degrees, in agreement with the NMR results. We have shown earlier that, among twenty possible conformers, phosphofructokinase acts specifically on the 4T3 conformer of the beta anomer of D-fructose 6-phosphate.

Carbohydrate Conformation↗
PubMed1992

Altered systemic and tissue prostacyclin in cerulein induced acute pancreatitis in rats.

Prostacyclin metabolism in rat acute pancreatitis was evaluated by measuring the tissue levels of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and the urinary excretion of 2, 3-dinor 6-keto-PGF1 alpha. Acute pancreatitis was induced by i.v. cerulein perfusion and was confirmed by the pancreas enzyme changes and the histological findings. Significantly enhanced tissue and urinary prostacyclin levels were found in acute pancreatitis rats, when compared to the controls. Concomitantly, an enhanced tissue phospholipase A2 (PLA2) activity was also found. These data show the importance of 2, 3-dinor PGF1 alpha as an inflammatory marker in cerulein-induced pancreatitis.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

Identification and structural analysis of a ribosomal RNA gene promoter from Thiobacillus ferrooxidans.

The 5'-terminus of a rRNA operon (rrnT2) from Thiobacillus ferrooxidans was characterized. The rRNA promoters from this microorganism were identified by means of a functional assay in Escherichia coli. DNA sequencing of the promoter region, upstream the 16 S rRNA gene, showed the presence of a consensus sequence for bacterial ribosomal promoters. Other features such as a 'discriminator' sequence, antiterminator elements and an upstream hexanucleotide common to several rRNA operons were also found. Two other putative transcription promoters were also identified.

Amino Acid Sequence↗
PubMed1990

Two-dimensional 1H-, 13C-, and 31P-nuclear magnetic resonance and molecular-mechanics investigation of D-fructose 2,6-bisphosphate.

Two-dimensional nuclear magnetic resonance studies have been carried out to assign unequivocally all the proton, carbon, and phosphorus resonances of D-fructofuranose 2,6-bisphosphate (1) and to verify its structure using a 400-MHz spectrometer. Several unexpected chemical-shift values and coupling constants were obtained. Molecular mechanics calculations (Sybyl) carried out to minimize the conformational energy of 1 yield phi C-1,P-2 = + 84, phi C-3,P-2 = - 155, and phi C-5,P-6 = + 175. Thus the unusual near-gauche orientations of C-1 and C-3 to P-2 in 1 can explain their small vicinal coupling constants (3JC-1,P-2 = 1.2, and 3JC-3,P-2 = 3.8 Hz), in contrast to the expected larger value seen for 3JC-5,P-6 namely, 6.9 Hz. Treatment of a sample of this compound with sodium borohydride did not affect its nuclear magnetic resonance spectrum, substantiating that O-2 is phosphorylated. Oxidation with sodium periodate yielded an intermediate which decomposed by a beta-elimination mechanism involving the 6-phosphate group. These data establish unequivocally the 1H, 13C, and 31P assignments and explain the observed anomalous shifts. Moreover they indicate that the activator of fructose 6-phosphate 1-kinase is the beta anomer of the 4T3 conformer of D-fructose 2,6-bisphosphate.

Carbon Isotopes↗
PubMed1988

Determination of molluscicidal sesquiterpene lactones from Ambrosia maritima (Compositae).

A high-performance liquid chromatographic method is described for the determination of sesquiterpene lactones in the molluscicidal plant Ambrosia maritima (Compositae). The four major constituent lactones were measured at 220 nm, using naphthalene as internal standard, and a comparison of different extraction procedures was carried out, with a view to investigating variations in sesquiterpene lactone content.

Chromatography, High Pressure Liquid↗
PubMed1988

The San Venero Roselli pharyngoplasty: an electromyographic study of the palatopharyngeus muscle.

Electromyography of the palatopharyngeus and salpingopharyngeus muscles was performed in three groups: normal subjects, subjects with cleft palate before surgical treatment, and subjects with repaired palatal clefts incorporating the San Venero Roselli pharyngoplasty. Results suggested that the salpingopharyngeus muscle is inconsistently present in man. The palatopharyngeus is primarily concerned with swallowing and is not active during velopharyngeal closure. Its activity is not affected by the San Venero Roselli procedure. The surgical approximation of this muscle may be advantageous because of its antagonistic action to the levator veli palatini.

Child, Preschool↗
PubMedDate not supplied

Nimodipine's effect on alcohol disposition in mice.

Adult Binghamton Heterogeneous male mice received either nimodipine (5 mg/kg in saline) or vehicle 10 minutes prior to ethanol (1.02 g/kg) administration. Blood samples were obtained at 2, 10, 30, 60 and 120 minutes following the alcohol injection for determination of ethanol content. Although mean blood alcohol concentrations (BACs) were similar for both groups, nimodipine increased the variance in blood alcohol levels. Therefore, while nimodipine may alter alcohol pharmacokinetics through its interaction(s) with the genetic characteristics of the individual animal, the ability of this calcium slow channel blocking agent to enhance the psychotropic effects of alcohol cannot be due to altered absorption or elimination of the intoxicant.

Animals↗