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Biomedical subjects

L Soto

Publications and source records attributed to L Soto.

At least 19 recordsLinked to original sources
PubMed2001

Two polymeric compounds built from mononuclear and tetrameric squarate-copper(II) complexes by deprotonation of 3,3-bis(2-imidazolyl)propionic acid (HBIP). Synthesis, crystal structure, and magnetic characterization of [Cu(HBIP)(BIP)](C(4)O(4))(1/2).2H(2)O and [[Cu(BIP)(OH(2))](4)(mu-C(4)O(4))](ClO(4))(2).4H(2)O.

Two polynuclear copper(II)-squarate compounds of formulas [Cu(HBIP)(BIP)](C(4)O(4))(1/2).2H(2)O (1) and [[Cu(BIP)(OH(2))](4)(mu-C(4)O(4))](ClO(4))(2).4H(2)O (2) (HBIP = 3,3-bis(2-imidazolyl)propionic acid) have been synthesized and characterized by single-crystal X-ray diffraction. Both compounds crystallize in the triclinic system, space group P1, with a =7.947(1) A, b =12.327(4) A, c = 13.150(3) A, alpha = 113.91(2) degrees, beta = 99.85(2) degrees, gamma = 90.02(2) degrees for compound 1 and a = 8.010(1) A, b = 13.073(1) A, c = 14.561(1) A, alpha = 72.13(1) degrees, beta = 80.14(1) degrees, gamma = 84.02(1) degrees for compound 2. The structure of compound 1 can be viewed as made up of [Cu(HBIP)(BIP)] units linked together by the BIP carboxylate groups to form a one-dimensional chain structure along the a axis in the crystal. The copper ion is five-coordinated (CuN(4)O chromophore) with BIP and HBIP acting as tridentate and bidentate ligands, respectively. The coordination geometry is intermediate between SP and TBP. The structure of compound 2 is made of infinite chains built from cationic tetranuclear [[Cu(BIP)(OH(2))](4)(mu-C(4)O(4))](2+) complex units, two uncoordinated perchlorate anions, and four water molecules of crystallization. The squarato group bridges the copper(II) ions, while BIP acts as a tridentate ligand, connecting through its carboxylate group the tetrameric units along the a axis. The two crystallographically independent copper(II) ions are pentacoordinated within a distorted square-based pyramid. Electronic and EPR spectra are consistent with the crystallographic data. Both compounds follow a Curie-Weiss law with very low values of theta (-0.13 and +0.12 K). In compound 2, the weak ferromagnetism interaction is discussed on the basis of the structural features and correlated with published magnetostructural data on similar squarato-bridged copper(II) compounds.

Journal Article↗
PubMed2001

Cyclosporin a treatment is able to revert the decrease in circulating GH and IGF-I and the increase in IGFBPs induced by adjuvant arthritis.

The aim of this study was to find out whether cyclosporin A administration is able to revert the decrease in circulating growth hormone (GH) and insulin-like growth factor-I (IGF-I) and the increase in IGF-binding proteins (IGFBPs) levels caused by adjuvant-induced arthritis in rats. Male Sprague-Dawley rats were intradermically injected with Freund's adjuvant or vehicle. Fourteen days later, rats were randomly divided into two groups - one injected with cyclosporin (15 mg/kg) and the other with vehicle from day 16 to 23 after adjuvant injection. Arthritis decreased body weight gain and serum concentrations of GH. Cyclosporin administration to arthritic rats prevented both effects, whereas cyclosporin had no effect in control rats. Arthritis decreased serum concentrations of IGF-I (p < 0.01), but increased IGFBPs. Cyclosporin administration increased circulating IGF-I, and there was a negative correlation between circulating IGF-I and arthritis index scores in arthritic rats injected with cyclosporin (p < 0.05). Cyclosporin treatment did not alter serum IGFBPs levels in control rats, whereas cyclosporin administration normalised IGFBPs in arthritic rats. These results indicate that the effects of cyclosporin administration on the GH-IGF-IGFBPs system may partly mediate its beneficial effect on body weight in arthritic rats.

Animals↗
PubMed2001

African swine fever virus protein p54 interacts with the microtubular motor complex through direct binding to light-chain dynein.

Dynein is a minus-end-directed microtubule-associated motor protein involved in cargo transport in the cytoplasm. African swine fever virus (ASFV), a large DNA virus, hijacks the microtubule motor complex cellular transport machinery during virus infection of the cell through direct binding of virus protein p54 to the light chain of cytoplasmic dynein (LC8). Interaction of p54 and LC8 occurs both in vitro and in cells, and the two proteins colocalize at the microtubular organizing center during viral infection. p50/dynamitin, a dominant-negative inhibitor of dynein-dynactin function, impeded ASFV infection, suggesting an essential role for dynein during virus infection. A 13-amino-acid domain of p54 was sufficient for binding to LC8, an SQT motif within this domain being critical for this binding. Direct binding of a viral structural protein to LC8, a small molecule of the dynein motor complex, could constitute a molecular mechanism for microtubule-mediated virus transport.

African Swine Fever Virus↗
PubMed2001

The decrease in hepatic IGF-I gene expression in arthritic rats is not associated with modifications in hepatic GH receptor mRNA.

OBJECTIVE: Adjuvant-induced arthritis induces a catabolic response, and a decrease in circulating IGF-I. Hypermetabolism and GH insensitivity have been described in acute inflammation. The aim of this study was to analyze whether impaired IGF-I secretion in arthritic rats can be attributed to hepatic GH resistance. DESIGN AND METHODS: Male Wistar rats were injected with complete Freund's adjuvant, and 14 days afterwards arthritic and control rats were injected daily with recombinant human GH (rhGH) (3 IU/kg) or saline for 8 days. GH receptor (GHR) gene expression in the liver and the effect of rhGH on hepatic IGF-I synthesis in arthritic rats were examined. RESULTS: There was a significant decrease in hepatic concentrations of IGF-I (P < 0.01) as well as in the IGF-I gene expression in arthritic but not in pair-fed rats. In contrast, arthritis did not modify GHR mRNA levels in the liver. The 8 day administration of rhGH resulted in an increase in body weight gain in arthritic but not in control rats. There was an increase in hepatic IGF-I synthesis and in GHR mRNA levels after rhGH treatment, both in control and in arthritic rats. Two endotoxin lipopolysaccharide (LPS) (1 mg/kg) injections decreased hepatic concentrations of IGF-I and IGF-I mRNA (P < 0.01). Contrary to the results obtained in arthritic rats, mRNA expression of GHR in the liver was lower in LPS- than in saline-treated rats (P < 0.01). CONCLUSION: These data suggest that the decrease in IGF-I synthesis induced by chronic arthritis is not secondary to GH resistance.

Animals↗
PubMed2000

How is mechanical ventilation employed in the intensive care unit? An international utilization review.

A 1-d point-prevalence study was performed with the aim of describing the characteristics of conventional mechanical ventilation in intensive care units ICUs from North America, South America, Spain, and Portugal. The study involved 412 medical-surgical ICUs and 1,638 patients receiving mechanical ventilation at the moment of the study. The main outcome measures were characterization of the indications for initiation of mechanical ventilation, the artificial airways used to deliver mechanical ventilation, the ventilator modes and settings, and the methods of weaning. The median age of the study patients was 61 yr, and the median duration of mechanical ventilation at the time of the study was 7 d. Common indications for the initiation of mechanical ventilation included acute respiratory failure (66%), acute exacerbation of chronic obstructive pulmonary disease (13%), coma (10%), and neuromuscular disorders (10%). Mechanical ventilation was delivered via an endotracheal tube in 75% of patients, a tracheostomy in 24%, and a facial mask in 1%. Ventilator modes consisted of assist/control ventilation in 47% of patients and 46% were ventilated with synchronized intermittent mandatory ventilation, pressure support, or the combination of both. The median tidal volume setting was 9 ml/kg in patients receiving assist/control and the median setting of pressure support was 18 cm H(2)O. Positive end-expiratory pressure was not employed in 31% of patients. Method of weaning varied considerably from country to country, and even within a country several methods were in use. We conclude that the primary indications for mechanical ventilation and the ventilator settings were remarkably similar across countries, but the selection of modes of mechanical ventilation and methods of weaning varied considerably from country to country.

Data Collection↗
PubMed2000

IGF-I and IGF-I-binding proteins in rats with adjuvant-induced arthritis given recombinant human growth hormone.

Adjuvant-induced arthritis in rats is associated with growth failure, hypermetabolism and accelerated protein breakdown. We have previously reported that adjuvant-induced arthritis in rats results in a decrease in body weight gain, pituitary GH mRNA, circulating GH and IGF-I together with an increase in serum IGF-binding proteins (IGFBPs). The aim of this study was to analyze the role of GH in the decrease in body weight and in the alterations in the IGF-I system observed in chronic inflammation. Male Wistar rats were injected with complete Freund's adjuvant and 16 days later arthritic rats were injected daily with recombinant human GH (rhGH) (3 IU/kg s.c.) for 8 days; control rats received 250 microl saline. Arthritis significantly decreased body weight gain and serum IGF-I. These decreases were not due to the reduced food intake, since in pair-fed rats they were not observed. Furthermore, administration of rhGH to arthritic rats increased body weight gain without modifying food intake. To further investigate the effect of GH administration, 14 days after adjuvant injection both control and arthritic rats were treated with 0, 1.5, 3 or 6 IU/kg of rhGH. GH treatment at the dose of 3 and 6 IU/kg significantly increased body weight gain in arthritic rats. GH administration, at the higher dose of 6 IU/kg, increased hepatic and serum concentrations of IGF-I in both control and arthritic rats. In control rats, rhGH at the three doses assayed increased circulating IGFBP-3. GH treatment in arthritic rats decreased IGFBP-1 and -2, and did not modify IGFBP-4. GH treatment at the dose of 3 IU/kg also decreased circulating IGFBP-3 in arthritic rats. These data suggest that GH treatment can ameliorate the catabolism observed in adjuvant-induced arthritis, an effect mediated, at least in part, by modifications in the circulating IGFBPs.

Animals↗
PubMed1999

The effect of cyclosporine administration on growth hormone release and serum concentrations of insulin-like growth factor-I in male rats.

The aim of this work was to study the effect of cyclosporine on the somatotropic axis. Accordingly, growth hormone (GH) secretion, circulating insulin-like growth factor I (IGF-I) and IGF binding proteins (IGFBPs) in response to cyclosporin A (CsA) treatment were examined in adult male Wistar rats. Cyclosporine administration (5, 10 or 20 mg/Kg daily) over 8 days did not modify the body weight, but it did decrease serum concentration of corticosterone and increased serum IGF-I and GH levels. Rats treated with 5 and 10 mg/Kg of cyclosporine had similar levels of serum IGFBPs to control rats, but there was an increase in circulating IGFBP-3 and IGFPB-1,2 in the group treated with 20 mg/Kg of CsA. The increase in circulating GH correlates with a decrease in pituitary GH content in CsA treated rats, with no modification in hypothalamic somatostatin content, suggesting an increase in pituitary GH release. In order to test this hypothesis, anterior pituitary cell cultures were exposed to different CsA concentrations during a 4 h incubation period. Cyclosporine increased GH secretion in cultured pituitary cells (p<0.05). These data suggest that cyclosporine increases circulating IGF-I and GH by stimulating pituitary GH release.

Animals↗
PubMed1999

Chronic inflammation inhibits GH secretion and alters the serum insulin-like growth factor system in rats.

Adjuvant-induced arthritis in rats is associated with growth failure, hypermetabolism and accelerated protein breakdown. The aim of this work was to study the effects of adjuvant-induced arthritis on GH and insulin-like growth factor-I (IGF-I). Arthritis was induced by an intradermal injection of complete Freund's adjuvant and rats were killed 18 and 22 days later. IGF-I and GH levels were measured by radioimmunoassay. Pituitary GH mRNA was analyzed by northern blot and IGF binding proteins (IGFBPs) by western blot. Arthritic rats showed a decrease in both serum and hepatic concentrations of IGF-I. On the contrary, arthritis increased the circulating IGFBPs. The serum concentration of IGF-I in the arthritic rats was negatively correlated with the body weight loss observed in these animals. Arthritis decreased the serum concentration of GH and this decrease seems to be due to an inhibition of GH synthesis, since pituitary GH mRNA content was decreased in arthritic rats (p<0.01). These data suggest that the decrease in body weight gain in arthritic rats may be, at least in part, secondary to the decrease in GH and IGF-I secretion. Furthermore, the increased serum IGFBPs may also be involved in the disease process.

Adrenal Glands↗
PubMed1999

Bacterial colonization patterns in mechanically ventilated patients with traumatic and medical head injury. Incidence, risk factors, and association with ventilator-associated pneumonia.

We prospectively evaluated the relation of upper airway, lower airway, and gastric colonization patterns with the development of pneumonia and its etiology in 48 patients with surgical (n = 25) and medical (n = 23) head injury. Initial colonization was assessed by cultures of nasal and pharyngeal swabs, tracheobronchial aspirates, gastric juice, and bronchoscopically retrieved protected specimen brush. Follow-up colonization was determined until the end points extubation, suspected ventilator-associated pneumonia (VAP), or death. The initial colonization rate at any site at ICU admission was 39/47 (83%). It mainly accounted for Group I pathogens (Streptococcus pneumoniae, Staphylococcus aureus, Hemophilus influenzae) of the upper and lower airways. At follow-up, colonization rates with Group II pathogens (Gram-negative enteric bacilli and Pseudomonas spp.) increased significantly. The high initial bacterial load with Group I pathogens of the upper airways and trachea decreased during Days 2 to 4, whereas that of Group II pathogens increased. Upper airway colonization was an independent predictor of follow-up tracheobronchial colonization (odds ratio [OR], 9.9; 95% confidence interval [CI], 1.8 to 56.3 for initial colonization with Group I pathogens; OR, 23.9; 95% CI, 3.8 to 153.3 for follow-up colonization with Group II pathogens). Previous (short-term) antibiotics had a protective effect against colonization with Group I pathogens of the lower respiratory tract (OR, 0.2; 95% CI, 0.05 to 0.86), but they were a risk factor for colonization with Group II pathogens (OR, 6.1; 95% CI, 1.3 to 29). Initial tracheobronchial colonization with Group I pathogens was associated with a higher probability of early onset pneumonia (OR, 4. 1; 95% CI, 0.7 to 23.3), whereas prolonged antibiotic treatment (> 24 h) independently predicted late-onset pneumonia (OR, 9.2; 95% CI, 1.7 to 51.3). We conclude that patients with head injury are colonized in the airways mainly by Group I pathogens early in the evolution of illness. The upper airways represent the main reservoir for subsequent lower airway colonization with Group I pathogens. Previous (short-term) antibiotic treatment is protective against initial tracheobronchial colonization with Group I pathogens, but it represents a risk factor for subsequent lower airway colonization by Group II pathogens.

Adult↗
PubMed1998

Effects of endotoxin lipopolysaccharide administration on the somatotropic axis.

The aim of this work was to study the effect of chronic activation of the immune system on the somatotropic axis. Accordingly, the changes in growth hormone (GH) secretion, circulating insulin-like growth factor-I (IGF-I) and IGF binding proteins (IGFBPs) in response to endotoxin lipopolysaccharide (LPS) administration were examined in adult male Wistar rats. Acute LPS injection (2.5, 25 or 250 microg/kg) increased serum corticosterone in a dose-dependent manner and decreased serum levels of insulin and IGF-I, serum GH concentration declined linearly as the LPS dose increased. Western ligand blot showed an increase in the 33 kDa band (corresponding to IGFBP-1 and IGFBP-2) in the rats that received the highest dose of LPS (250 microg/kg). Chronic LPS administration (250 microg/kg daily for 8 days) significantly decreased body weight, serum levels of IGF-I and pituitary GH content, whereas it increased circulating IGFBP-3 (47 kDa band), IGFBP-1 and IGFBP-2 (33 kDa band) and the 24 kDa band (which possibly corresponds to IGFBP-4). Serum concentration of corticosterone and hypothalamic somatostatin content were also increased by chronic LPS treatment. These data suggest that the decrease in GH and IGF-I secretion and the increase in circulating IGFBPs are important mechanisms in body weight loss during chronic inflammation.

Animals↗
PubMed1996

Short and long restraint differentially affect humoral and cellular immune functions.

The aim of this work was to examine the effect of different periods of restraint on the humoral and cellular immune functions in adult male rats. Short restraint stress (2 h over 2 consecutive days) enhanced the primary serum antibody response to sheep red blood cells. The enhancement of this humoral response was dependent on the restraint period, since long restraint stress (6 h over 4 days) failed to modify this response. Short and long restraint decreased both the number of lymphocytes and the T-lymphocyte response to Con A stimulation in the peripheral blood. Neither 2 h over 2 days nor 6 h over 4 days modified the splenic lymphoproliferative response to Con A stimulation, but restraint stress progressively decreased the number of mononuclear splenic cells. Both periods of restraint significantly increased plasma concentration of corticosterone, however plasma prolactin levels were significantly lower after 4 days of restraint but not after short restraint (2 h over 2 days). These results indicate that although some immune functions can be increased after acute or short stress, long stress has an immunosuppressive effect, above all on the cellular immunity which is more susceptible to this effect than the humoral response.

Animals↗
PubMed1996

Do intestinal parasites interfere with the seroepidemiologic surveillance of Schistosoma mansoni infection?

In view of the known cross-reactivity of sera from patients with intestinal parasites to some Schistosoma mansoni antigens, field work was conducted in an area of Venezuela non-endemic for schistosomiasis using the routine immunoenzymatic assay (ELISA) with soluble egg antigen (SEA). False positive reactions represented 15.3% of the total population as determined by SEA-ELISA. SEA-immunoblotting of the false positive sera indicated that protein fractions of 91 and 80 kDa appear to be responsible for cross-reactivity. Sera from hookworm infected individuals produced a higher frequency and intensity of cross-reaction than other sera. SEA-fractions of 105, 54, 46, 42, 32, 25 and 15 kDa were the most specific.

Adolescent↗
PubMed1995

Determination of anions in human and animal tear fluid and blood serum by ion chromatography.

An important factor contributing to the development of ion chromatography (IC) has been the need for repetitive analyses of samples with high ionic contents and samples available in microvolumes. IC was selected for the determination of Cl, NO3, SO(2-)4 and PO(3-)4 anions in tear fluid and serum from ten human volunteers of both sexes, seven young-adult black vultures (Coragyps atratus) and three young-adult chickens (Gallus gallus domesticus). The samples were analysed on a Dionex Model 2000i/SP ion-exchange chromatograph equipped with an anion guard column (Dionex IonPac AG4A), anion separator column (Dionex IonPac AS4A), suppressor column (Dionex AMMS-II) and a conductivity detector. The flow-rte of the mobile phase, 1.7 mM NaHCO3 - 1.8 mM Na2CO3 was set at 2.0 ml/min. The R.S.D. was calculated to be less than 1.5% for all anions. In the human, black vulture and chicken serum samples, the NO3, PO(3-)4 and SO(2-)4 anion contents were higher than in tears; for Cl the reverse was found. No correlation was found amongst the anion concentrations present in the tear fluid and blood serum in all samples (p > 0.05). With no sample treatment, column maintenance was required.

Adolescent↗
PubMed1994

[Detection of anti-gonococcal antibodies using a dot immunobinding assay in a high risk female population].

The bacteriological diagnosis of gonorrhea in women has a low efficiency. A dot immunobinding assay, using whole piliated Neisseria gonorrhoeae cells, was used to detect antigonococcal antibodies in 300 prostitutes in whom a parallel Thayer-Martin culture of endocervical secretion was performed. Twenty sera from men with bacteriologically confirmed gonorrhoea were used as positive controls and 20 sera from children without history of gonococcal infections, as negative controls. Antibodies were detected in 49.7% of women and culture was positive in only one. All men with gonorrhea has positive titers and all sera from children were negative, except one that had a cross-reaction. Test sensitivity in the female population was 1 and specificity 0.5. There were no false negative reactions. Although the test detected antibodies in high risk women, there were cross-reactions. Therefore, the technique should be improved, using a more specific antigen.

Antibodies, Bacterial↗
PubMed1993

[Frequency of sickle-cell anemia in the population of "Cuatro Bocas," Parroquia Ricaurte, Mara municipality, Zulia state, Venezuela].

Isla de Toas is an island on the north of the Maracaibo Lake, it is known in the scientific community, for the high frequency of sickle cell disease, in a population with caucasoid phenotype. The purpose of the present work was to determine the frequency of sickle cell anemia in the population of Cuatro Bocas, situated 35 km from the southwest of Isla de Toas. The town is the center of confluence of a rural population constituted mainly of farmers. The sample consisted of 870 persons of both sexes, aged from 8 months to 66 years. The presence of the sickling phenomenon was determined in all the individuals, and hemoglobin electrophoresis in agarose was performed in all the positive samples. The following results were obtained: fifty-six cases (6.4%), showed drepanocytic changes, and forty-six of them were haemoglobin A/S, 8 were S/S and 2 were S/C. The higher frequency of hemoglobin S was in adolescents and adults. The family backgrounds suggest an insular origin of the sickle cell gene. About 75% of the affected population was ignorant of this condition. The hemoglobin values were lower in the individuals with the sickle cell disease (p < 0.05), than in the normal persons. Iron deficiency in adolescents was suspected because or their low hemoglobin values. The results indicate that the sickle cell gen is expanding to the nearest communities of the Mara county. It is important to consider that the findings of the present work should serve as an alert to the Public Health authorities, and that education of the population is important in order to prevent the spreading of the disease.

Adolescent↗