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J M Lozano

Publications and source records attributed to J M Lozano.

34 records · Page 2Linked to original sources
PubMed1998

Effect of undernutrition on the distribution of progesterone in the uterus of ewes during the luteal phase of the estrous cycle.

The effect of undernutrition on ovarian and uterine venous progesterone concentrations and endometrial progesterone content on Days 5 and 10 of the estrous cycle were studied. Forty ewes were synchronized using progestagen pessaries. At pessary withdrawal, the ewes were fed diets to provide either 1.5 or 0.5 times the daily maintenance requirement (Group H, n = 20 and Group L, n = 20, respectively). Ewes fed the low nutrition diet (Group L) had higher mean peripheral progesterone concentrations than those fed the high plane diet (Group H; P < 0.05) but lower endometrial progesterone content on Day 5 (P < 0.05). Neither ovarian nor uterine venous levels were affected by nutrition on either Day 5 or 10. Progesterone concentrations in blood samples collected ipsilateral to ovaries bearing a corpus luteum (CL) were higher than in the contralateral samples (P < 0.001). It is concluded that undernutrition can produce a reduction of endometrial content of progesterone the first week after mating. Since no differences in ovarian venous concentrations were observed, it remains to be shown whether this variation is due to other variables, such as the population of endometrial progesterone receptors or other nonhormonal factors.

Animals↗
PubMed1998

Reduced amide pseudopeptide analogues of a malaria peptide possess secondary structural elements responsible for induction of functional antibodies which react with native proteins expressed in Plasmodium falciparum erythrocyte stages.

A psi[CH2NH] isoster bond was introduced by replacing one peptide bond at a time within the 1513 malaria peptide KEKMV motif to obtain a set of five pseudopeptides. The motif belongs to a Plasmodium falciparum malarial peptide coded 1513, derived from the MSP-1 protein. This high-binding motif included in the 1513 peptide is involved in the attachment of the malarial parasite to human erythrocytes. The novel malaria 1513 psi[CH2NH] surrogates were analyzed using RP-HPLC and MALDI-TOF mass spectrometry techniques. Nuclear magnetic resonance experiments allowed definition of the five pseudopeptide analogues' secondary structural features. Such structures are present in only a very few molecules in the 1513 parent peptide. A molecular model demonstrating the solution of the three-dimensional structure of the 1 513 peptide Pse-437 analogue was constructed on the basis of 1H-NMR spectral parameters. Monoclonal antibodies were generated to the five 1513 malaria peptide pseudopeptide analogues. These antibodies not only recognize the native MSP-1 (195 kDa) and its 83 kDa and 42 kDa proteolytic processing proteins but also different SPf(66)n malaria vaccine batches containing the native sequence. In addition, the mAbs were able to modify the kinetics of Plasmodium falciparum parasites' intraerythrocytic development and their ability to invade new RBCs. The presented evidence suggests that peptide bond-modified peptides could reproduce a transient state in 1513's native sequence and represent useful candidates in the development of a second generation of effective malarial vaccines.

Amides↗
PubMed1998

Effect of PGE1 on TNF-alpha status and hepatic D-galactosamine-induced apoptosis in rats.

Prostaglandin E1 has hepatoprotective properties in several clinical and experimental models of liver dysfunction. Hepatotoxicity induced by D-galactosamine (D-GalN) is a suitable animal model of human acute hepatic failure. The aim of the study was to investigate if prostaglandin E1 (PGE1) protection against hepatic D-GalN-induced apoptosis was related to tumour necrosis factor-alpha (TNF-alpha) content in serum. This cytokine is associated with in vitro apoptosis and general inflammatory disorders. In this study, PGE1 was administered 30 min before D-GalN to rats. In other experiments, several doses of TNF-alpha were administered 15min after PGE1 to D-Ga1N-treated rats. Several parameters related to apoptosis and necrosis were measured by flow cytometry, gel electrophoresis, biochemical analysis, and optical and electron microscopy. Tumour necrosis factor-alpha was quantified by competitive enzyme-linked immunosorbent assay (ELISA). PGE1 by itself did not modify the cell cycle of hepatocytes and liver toxicity, but increased TNF-alpha in serum in comparison with the control group. D-Galactosamine increased the percentage of hepatocytes in apoptosis and in the S phase of the cell cycle, and decreased those in G0/G1. Such an increase of hepatocytes in apoptosis was correlated with a higher number of apoptotic bodies and DNA fragmentation in liver than control samples. Also, D-GalN increased alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and TNF-alpha in serum compared with the control group. Pre-administration of PGE1 to D-GalN-treated rats reduced all the parameters of apoptosis and necrosis in liver, and increased additionallyTNF-alpha content in serum. In those experiments where low doses of TNF-alpha were administered to PGE1 and D-GalN-treated rats an inverse relationship appeared between TNF-alpha and ALT content in serum. In conclusion, the protective effects of PGE1 on D-GalN-induced apoptosis may be linked to its capacity to modulate cell division and/or its immunomodulatory activity. In this sense, our experimental results suggest that TNF-alpha could be involved in protection or exacerbation of liver damage in relation to the pathophysiological status of the liver.

Alprostadil↗
PubMed1998

The effects of RGD (Arg-Gly-Asp) peptides on glaucoma filtration surgery in rabbits.

BACKGROUND AND OBJECTIVE: Integrins are the main mediators of the interaction between fibroblasts and extracellular matrix (ECM) during scar formation. The adhesion motive RGD (Arg-Gly-Asp) is contained in the ECM and is recognized by the integrin receptor. Soluble peptides containing the RGD sequence can compete with -RGD- contained in the ECM for binding to the integrin receptor and thus prevent cell adhesion and scar formation. MATERIALS AND METHODS: The peptides RGD (p602), GRGDSP (p603), GRGDSPCA (p604), and GGRGDSPCA (p605) were used in 25 glaucoma filtering surgeries in rabbits (five eyes per peptide and five with saline). RESULTS: Postoperative subconjunctival injections of peptides were given at days 0, 4, 8, 12, and 16. Bleb size, bleb survival, and signs of toxicity were examined. The GRGDSPCA and GGRGDSPCA showed an increase in bleb formation, size, and survival with no clinical signs of toxicity compared with controls (P < .008). Histopathologic evaluation confirmed inhibitory effects in scar formation with bleb formation, and transmission electron microscopy demonstrated that there was no toxicity to the ciliary body. CONCLUSION: These peptides were effective in controlling scar formation in glaucoma filtering surgery.

Animals↗
PubMed1997

Acute lymphoblastic leukemia in children: nonrandomized comparison of conventional vs. intensive chemotherapy at the National Cancer Institute of Colombia.

BACKGROUND: This study aimed to compare the therapeutic efficacy of two treatments for childhood acute lymphoblastic leukemia (ALL), and to evaluate the feasibility of intensive chemotherapy in a developing country. METHODS: The study was conducted at the National Cancer Institute in Bogota, Colombia. Untreated ALL patients under 16 years of age were divided into two groups: a historical control cohort (HC) of 141 patients treated with conventional chemotherapy and an intensive chemotherapy cohort (IC) of 130 patients treated with a modified Berlin-Frankfurt-Münster protocol (m-BFM). Patients were clinically classified into risk categories for relapse, and followed through July 31, 1995. Disease-free survival (DFS) curves were obtained using the Kaplan-Meier method and were compared by the log rank test. RESULTS: Therapy groups had similar clinical baseline characteristics. Nonresponse rate to induction was higher in the HC group (16.3%) than in the IC cohort (7.6%) (P = 0.047), but deaths during induction were more frequent among m-BFM patients (13.8%) than in the HC group (6.4%) (P = 0.064). Bone marrow relapses after complete remission were less common in the IC group than in the HC group (19.4% and 45.9%, respectively; P = 0.0001), but central nervous system relapses showed no difference (12.8% in the HC and 16.3% under IC; P = 0.6). The DFS rates at 10 years were higher for the IC group, regardless of the baseline risk. CONCLUSIONS: IC reduces the frequency of relapses in ALL children in developing countries, when compared to previous therapy. A highly effective therapy such as m-BFM seems to be the most important predictor of outcome in children.

Adolescent↗
PubMed1997

Effect of level of dietary energy and protein on embryo survival and progesterone production on day eight of pregnancy in Rasa Aragonesa ewes.

The aim of this experiment was to investigate the effects of dietary protein and energy on ovulation rate and embryo survival to day 8 of pregnancy, and the associated concentrations of progesterone in jugular, ovarian and uterine veins, in a Spanish breed of sheep. In mid-October, three groups of ewes were fed to provide 1.5 x (H; n = 9), 0.5 x (L; n = 12) or 0.5 x plus 7.44 g CP/MJ ME (LP; n = 8) energy requirements for maintenance of live weight from day -14 relative to a synchronized mating on day 0. A significant effect of nutrition on ovulation rate was observed (H: 2.22 +/- 0.16; L: 1.50 +/- 0.16; LP: 1.88 +/- 0.12 corpora lutea; P < 0.05). Mean LH and progesterone concentrations were affected by nutrition on day 7, L ewes showing the highest mean LH level (P < 0.01), while H ewes presented the lowest mean LH concentration and the highest mean plasma progesterone concentration (P < 0.01). Laparotomies were performed on six animals of each group on day 8 to determine the effect of nutrition on embryo development. A significantly higher percentage of embryos recovered from L and LP ewes presented an earlier stage of development (morulae or early blastocysts) (P < 0.001), while 100% embryos of H ewes were expanded blastocysts. The ratio expanded blastocysts/corpora lutea was significantly higher in H ewes (0.86) when compared with L and LP groups together (0.57; P < 0.05). Mean progesterone concentration in the ovarian vein was 800-fold higher than mean jugular venous levels with no differences between groups. Samples from ovarian veins contralateral to corpus luteum-bearing ovaries showed mean progesterone concentrations significantly lower than samples opposite to corpus luteum (ipsilateral: 1037.84 +/- 138.45; contralateral: 30.4 +/- 11.22 ng/ml; P < 0.001). Mean progesterone concentration in the uterine vein was approximately 30-fold higher than in jugular and similar in both uterine horns and treatments. No effect of nutrition on pregnancy rate was observed (H: 89%; L: 92%; LP: 100%). These results suggest that neither dietary energy nor protein are able to modify pregnancy rate or progesterone concentrations in ovarian and uterine veins eight days after mating. However, the delay in embryo development observed in the embryos collected from L and LP ewes may give rise to compromised embryo growth and development some days later.

Animal Nutritional Physiological Phenomena↗
PubMed1996

[Comparative study of HELISAL T.M. RAPID BLOOD and ELISA, JATROX and pathologic anatomy in the diagnosis of Helicobacter pylori infection].

OBJECTIVES: To assess the usefulness of HELISAL in the diagnosis of Helicobacter pylori infection by comparing it with ELISA, JATROX and histopathologic findings. EXPERIMENTAL DESIGN: Randomized prospective study. PATIENTS: Sixty-one patients, thirty-three males and twenty-eight females, 18-73 years old, submitted to esophagogastroduodenoscopy. RESULTS: The sensitivity of HELISAL when compared to ELISA test was 60.8%, the specificity 73.3%, the positive predictive value 87.5%, the negative predictive value 37.9%, and the kappa index 0.26. When compared to histopathologic test: sensitivity 60.9%, specificity 65%, positive predictive value 78.1%, negative predictive value 44.7%, kappa 0.28. When compared to JATROX, sensitivity 57.7%, specificity 62.5%, positive predictive value 81.2%, negative predictive value 34.4%, kappa 0.21. CONCLUSION: The sensitivity of HELISAL test is lower than that of other compared tests, and the negative predictive value is very low. The specificity and the positive predictive value are higher than the sensitivity. The kappa index shows a very low concordance.

Adult↗
PubMed1994

Clinical predictors of acute radiological pneumonia and hypoxaemia at high altitude.

Fast breathing has been recommended as a predictor of childhood pneumonia. Children living at high altitude, however, may breathe faster in response to the lower oxygen partial pressure, which may change the accuracy of prediction of a high respiratory rate. To assess the usefulness of clinical manifestations in the diagnosis of radiological pneumonia or hypoxaemia, or both, at high altitude (2640 m above sea level), 200 children aged 7 days to 36 months presenting to an urban emergency room with cough lasting less than seven days were studied. Parents were interviewed and the children evaluated using standard forms. The results of chest radiographs and pulse oximetry obtained after clinical examination were interpreted blind. Radiological pneumonia and haemoglobin oxygen saturation < 88% were used as 'gold standards'. One hundred and thirty (65%) and 125 (63%) children had radiological pneumonia and hypoxaemia respectively. Crepitations and decreased breath sounds were statistically associated with pneumonia, and rapid breathing as perceived by the child's mother, chest retractions, nasal flaring, and crepitations with hypoxaemia. The best single predictor of the presence of pneumonia is a high respiratory rate, although the results are not as good as those reported by other studies. A respiratory rate > or = 50/minute had good sensitivity (76%) and specificity (71%) for hypoxaemia in infants. Hypoxaemia had a good sensitivity and specificity for pneumonia mainly in infants (83% and 73%, respectively). Logistic regression analysis showed that decreased or increased respiratory sounds and crepitations were associated with pneumonia, and that hypoxaemia is the best predictor when auscultatory findings are excluded. These results suggest that some clinical predictors appear to be less accurate in Bogota than in places at lower altitude, and that pulse oximetry can be used for predicting pneumonia.

Acute Disease↗
PubMed1994

Lactose vs. lactose free regimen in children with acute diarrhoea: a randomized controlled trial.

OBJECTIVE: To determine whether the routine use of a lactose free formula (AL-110, Nestle Labs.) in hospitalized children aged one to 24 months reduces the duration of acute diarrhea (AD). METHODS: After being stratified according to age and nutritional state, 28 and 24 patients were randomly allocated to receive AL-110 or lactose formula, respectively. The main outcome was the duration of diarrhoea after refeeding, both in hours and days. Secondary outcomes were evaluated by blind observers. Results were compared using t test, the Mann-Whitney test and Chi square. RESULTS: No differences were found between the diets without and with lactose regarding duration of diarrhoea in hours (mean, 41.9 h vs 54.4 h; p = 0.247) or days (median, 0 d vs 0 d; p = 0.717), the percentage of failures (3.6% vs 8.3; p = 0.2), and the mean weight increment (0.78 kg vs. 0.82 kg; p = 0.788). The study power to find a 50% (27h) reduction of AD duration was 71%. CONCLUSION: Although the power of this trial was slightly below that previously fixed (80%), the results suggest that routine use of lactose free formula does not reduce the duration of AD in hospitalized children.

Acute Disease↗
PubMed1993

Effect of plane of protein after weaning on resumption of reproductive activity in Rasa Aragonesa ewes lambing in late spring.

The effect of protein supplementation after weaning on the resumption of reproductive activity in a Spanish breed of ewes (Rasa Aragonesa) with a reduced seasonality was studied. Two equal groups of ewes were weaned in the first 2 weeks of July. From weaning to the end of the experiment both groups were fed identical energy-content rations but with different protein levels (high, Group H; low, Group L). The mean time between weaning and first detected estrus was 64 days. No differences between groups were found either in relation to this interval or in the ovulation rate in the first estrus. Ewes showing a multiple ovulation rate in the first cycle anticipated the onset of sexual activity after weaning. Significant differences in the ovulation rate were detected between the 2 groups from September to the end of the experiment (1.55 vs 1.05 corpora lutea for Groups H and L, respectively; P<0.001). In conclusion, the effect of a protein supplement after weaning in Rasa Aragonesa ewes lambing in late spring is reflected at mid-term in the early breeding season, with an evident rise of ovulation rate in the nutrient supplemented group.

Journal Article↗
PubMed1992

Pulse oximetry reference values at high altitude.

Pulse oximetry is becoming popular for measuring oxygen saturation of haemoglobin in paediatric patients. There are no reference values for children living at high altitudes, and the aim of this study was to determine the values of oxygen saturation of haemoglobin in healthy children in Bogota (2640 m above sea level). The saturation was determined in 189 children aged 5 days to 24 months with a Nellcor N10 oximeter. Mean values and 95% confidence intervals (CI) were calculated. Analysis of variance was used for assessing the differences in saturation with age and physiological status. The values were normally distributed with a mean (SD) of 93.3 (2.05)% and 95% CI of 93.0% to 93.6%. There were no clinically important differences in the oxygen saturation of haemoglobin in the range of ages included. The mean saturation in sleeping children was significantly lower than that during other physiological states (91.1% v 93.3%) but the difference was not clinically important. As expected, the values for the oxygen saturation of haemoglobin in the children studied were lower than those reported from children living at sea level. These estimates can be used for interpreting results of the oxygen saturation in haemoglobin in children from Bogota and other cities located at a similar altitude.

Altitude↗
PubMedDate not supplied

Cultivation and characterization of stable Leishmania guyanensis complex axenic amastigotes derived from infected U937 cells.

The study of the differential regulation of several genes, in both Leishmania parasite life cycle forms, has been simplified by the development of in vitro axenic amastigote culture. Different reports have described extracellular amastigote production and maintenance from several Leishmania spp. A general approach to induce amastigote-like transformation includes progressive pH and temperature changes. Production of axenic amastigotes in continuous cultures using amastigotes recovered from macrophages is described in this report. Leishmania (Viannia) panamensis (M/HOM/PA/71/LS94) and Leishmania (V). guyanensis (M/HOM/BR/75/M4147) intracellular amastigotes were recovered from the human macrophage-like U937 cell line previously infected with promastigotes. The parasites were immediately adapted for growth and kept as axenic amastigotes at 34 degrees C and acidic pH. These organisms were able to infect macrophage cell lines, maintain amastigote morphologic features, and express stage-specific transcripts. The relevance of axenic amastigotes in characterizing virulence factors in American leishmaniasis is discussed.

Animals↗
PubMedDate not supplied

GGRGDSPCA peptide: a new antiscarring agent on glaucoma filtration surgery.

BACKGROUND AND OBJECTIVE: GGRGDSPCA synthetic peptide competes for integrin receptor in scar formation after glaucoma filtering surgery in a rabbit model. The purpose of this study was to evaluate the use of this peptide and compare it with mitomycin on glaucoma filtering surgery. MATERIALS AND METHODS: Posterior sclerectomy was performed in both eyes of 17 rabbits. The right eye received GGRGDSPCA (p605) at 0, 4, 8, 12, and 16 days after. Nine left eyes received saline as a control; the remaining 8 eyes received mitomycin C at 0.5 mg/mL intraoperative. Intraocular pressures and biomicroscopy were evaluated as well as bleb function. RESULTS: Intraocular pressure decreased significantly in both the peptide and mitomycin treated eyes in comparison with the saline group (P = 0.0003). Pressure was similar in both groups. The blebs showed filtrating function in a functional analysis at day 21 and 41 in the mitomycin cases as well as in the peptide group. Histologic analysis performed in both peptide and mitomycin groups showed inhibitory effect in fibrocellular and collagen organization with bleb formation. CONCLUSIONS: The p605 peptide showed to be similar to mitomycin C in controlling and improving glaucoma filtering surgery in rabbits. This alternative may potentially be useful for similar purposes in humans for the control of glaucoma and improvement of filtering surgery.

Animals↗
PubMedDate not supplied

Cytokines and acute-phase response markers derangements in patients with obstructive jaundice.

BACKGROUND/AIMS: Prolonged acute-phase response and increase of cytokines have been associated with higher mortality and surgical complications. This study investigated the status of cytokines and acute-phase response markers in patients with obstructive jaundice. METHODOLOGY: Forty-one patients were investigated. Endotoxin, tumor necrosis factor-alpha, interleukin-6, nitric oxide, C-reactive protein, liver enzymes, albumin and percentage of weight loss were determined at admission. RESULTS: Endotoxin, interleukin-6 and C-reactive protein were significantly elevated in both benign and malignant obstructive jaundice. Increased plasma levels of tumor necrosis factor-alpha were only detected in malignant tumors (68 vs. 24 pg/mL; P < 0.001). Patients with positive acute-phase response (C-reactive protein > mean + 2 SD of controls) had greater weight loss (P = 0.02), endotoxin (P = 0.03) and interleukin-6 plasma levels (P = 0.05) than those with no inflammatory response. Prolonged biliary obstruction (> 10 days) was associated with higher weight loss (P = 0.04), tumor necrosis factor-alpha (P = 0.003) and interleukin-6 (P = 0.05) plasma levels. CONCLUSIONS: A prolonged high-grade biliary tract obstruction prompted an increase in endotoxin levels, associated with a positive acute-phase response and cytokine elevation.

Acute-Phase Proteins↗