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Biomedical subjects

M Romero

Publications and source records attributed to M Romero.

At least 19 recordsLinked to original sources
PubMed2002

Diversity of Bacillus thuringiensis strains from Colombia with insecticidal activity against Spodoptera frugiperda (Lepidoptera:Noctuidae).

AIMS: To identify and characterize Bacillus thuringiensis strains highly toxic to Spodoptera frugiperda, and to explore the genetic diversity of such strains. METHODS AND RESULTS: The insecticidal activity of 1100 strains of B. thuringiensis from Colombian soil samples was assayed against first instar S. frugiperda larvae, and 32 active strains were found. After a second bioassay evaluation, the eight most potent strains were selected for further characterization, which included crystal protein profiles determined by polyacrylamide gel electrophoresis, plasmid profile, plasmid restriction patterns, cry gene composition, qualitative determination of beta-exotoxin production, random amplified polymorphic DNA, serotyping, and toxicity to S. frugiperda. All Colombian strains contained cry1Aa, cry1Ab, cry1Ac, cry1B, cry1C and cry1D genes. However, PCR profiles of the Colombian strains suggested the presence of variants of the cry1 genes. Serotyping indicated that these strains belong to the kurstaki, thuringiensis, canadiensis and indiana subspecies. Interestingly, three strains belonging to different serotypes and subspecies were found in the same soil sample, and toxicity ranged between 11 and 976 ng cm(-2) of diet. CONCLUSIONS: It has been shown that B. thuringiensis strains belonging to different serotypes and displaying variable potency to S. frugiperda larvae can be found in the same soil sample. SIGNIFICANCE AND IMPACT OF THE STUDY: The results obtained indicate that some of the B. thuringiensis strains studied could be of interest for further development for S. frugiperda control programmes.

Animals↗
PubMed2001

The etiology of maternal mortality in developing countries: what do verbal autopsies tell us?

OBJECTIVE: To reassess the practical value of verbal autopsy data, which, in the absence of more definitive information, have been used to describe the causes of maternal mortality and to identify priorities in programmes intended to save women's lives in developing countries. METHODS: We reanalysed verbal autopsy data from a study of 145 maternal deaths that occurred in Guerrero, Querétaro and San Luis Potosí, Mexico, in 1995, taking into account other causes of death and the WHO classification system. The results were also compared with information given on imperfect death certificates. FINDINGS: The reclassification showed wide variations in the attribution of maternal deaths to single specific medical causes. CONCLUSION: The verbal autopsy methodology has inherent limitations as a means of obtaining histories of medical events. At best it may reconfirm the knowledge that mortality among poor women with little access to medical care is higher than that among wealthier women who have better access to such care.

Adult↗
PubMed2001

Long-term results of endovascular stent placement in the superior caval venous system.

PURPOSE: To present the long-term results in superior caval stenting for symptomatic obstruction. METHODS: Forty-nine stents were placed in 30 patients: 16 (53%) with malignant lesions, five (17%) with benign lesions and nine (30%) hemodialysis patients. Self-expandable stents were deployed on a first-line basis. Patients were followed clinically as well as by various imaging techniques and survival analysis was performed. RESULTS: Stent deployment was possible in all cases. Reocclusion was seen in 13 patients, of whom eight belonged to the hemodialysis group. Primary and secondary patency rates for malignant, benign and hemodialysis patients were respectively 74%, 50% and 22%, and 74%, 75% and 56% at 1 year. We had 7% complications and one death from iatrogenic superior vena cava injury. CONCLUSION: Primary stenting of superior caval obstruction is a first-choice treatment method achieving good mid-term patency. Patients with hemodialysis shunts must be closely monitored for early reintervention.

Adenocarcinoma↗
PubMed2001

Blood flow rate and energy charge in the isolated perfused canine liver.

Background. Liver viability depends on blood flow rate, which varies among isolated perfused livers used in different studies. We aimed to identify the minimal blood flow capable of keeping the energy charge compatible with liver viability. Materials and methods. Isolated canine livers were assigned to different groups (n = 4) with blood flow rates of 0.5 (Group I), 1.0 (Group II), and 1.5 ml/g/min (Group III). Blood gases, hematocrit, and glucose were measured over 180 min. Nucleotides, serum osmolarity, and electrolytes were also measured. Morphological changes were recorded at the end of each experiment. Results. Acid-base balance was better in livers from Group III. Electrolytes, osmolarity, hematocrit, and glucose showed no differences. Higher energy charges correlated with higher blood flow rates. On histopathology, there was evidence of more hydrostatic pressure-related changes in Group III, with no difference in necrosis or inflammatory-related alterations. Conclusions. (1) Energy charge correlates strongly with blood flow rate. (2) A rate of 1.5 ml/g/min allows for a better electrolyte, osmolarity, and acid-base balance. (3) Morphological analysis is not a sensitive predictor of organ viability as assessed by energetic potential. (4) The minimal blood flow rate required to attain an energy charge above 0.75 is 1.33 ml/g/min.

Acid-Base Equilibrium↗
PubMed2001

Characterisitcs of patients having thyroid surgery under regional anesthesia.

BACKGROUND: Recently local/regional anesthesia has been reintroduced as an alternative to general anesthesia for thyroidectomy. This study was undertaken to analyze characteristics and outcomes of patients who had thyroid surgery performed under regional anesthesia compared with those who had thyroidectomy under general anesthesia. STUDY DESIGN: One hundred seventy-five consecutive patients who underwent thyroid surgery under regional or general anesthesia during a 3-year period were analyzed. Fifty-eight operations were performed under regional anesthesia and 116 under general anesthesia. Patient characteristics analyzed included age, gender, obesity, anesthesia class, and tumor pathology. Postoperative complications, including nausea or vomiting, were compared. Additionally, operative times and length of stay in each group were compared. RESULTS: Patient characteristics including age, gender, tumor pathology, and anesthesia class were similar in both groups. But only 2% of patients treated under regional anesthesia were obese compared with 23% under general anesthesia. Although not significant, there was a trend toward decreased incidence of nausea and vomiting in the regional group. Other complications for the regional and general anesthesia groups were equal at 3%. Two patients required conversion to general anesthesia. Complications in the general anesthesia group included one episode of transient symptomatic hypocalcemia, two patients with transient vocal cord paralysis, and one episode of hematoma. Finally, there was a statistically significant increase in total operating room time and length of stay for the general anesthesia group. CONCLUSIONS: Regional anesthesia is a safe alternative to general anesthesia for patients undergoing thyroid surgery. Patients who cannot communicate verbally with the surgical team or who are obese may not be ideal candidates for regional anesthesia. The use of regional anesthesia results in a decreased length of stay and similar operative and operating room times.

Adolescent↗
PubMed2001

Intrahepatic expression of inducible nitric oxide synthase in acute liver allograft rejection: evidence of modulation by corticosteroids.

Nitric oxide (NO) has been proposed to have an important role in the immune response. Plasma nitrate levels increase during acute rejection and decrease after treatment with corticosteroids, but little is known about its potential cellular source. We studied inducible NO synthase (iNOS) expression in liver biopsy specimens of 12 patients with acute rejection compared with biopsy specimens from the same patients after treatment with high doses of intravenous corticosteroids. We also compared iNOS expression during acute rejection with a control group (9 patients without histological rejection). iNOS expression was assessed by immunohistochemistry. Intrahepatic iNOS expression was only observed in the cytoplasm of hepatocytes, which were diffusely distributed throughout hepatic lobules. iNOS expression could not be shown in portal tracts, inflammatory cells, or endothelial and sinusoidal lining cells. In patients with acute rejection, iNOS expression was significantly stronger than in the control group (2 +/- 0.7 v 0.6 +/- 0.7; P <.05). After treatment with corticosteroids, iNOS expression decreased significantly (2 +/- 0.7 v 1.3 +/- 0.9; P <.05). In conclusion, the findings of the present study show that during acute liver rejection, hepatocytes are the main cellular source for NO production and treatment with corticosteroids induces significant downregulation of intrahepatic iNOS expression.

Adrenal Cortex Hormones↗
PubMed2001

Multiple micronutrient supplementation increases the growth of Mexican infants.

BACKGROUND: The role of single micronutrient deficiencies in the etiology of growth retardation has recently gained attention. However, because multiple micronutrient deficiencies are common in children in developing countries, it is possible that more than one micronutrient may limit growth and, hence, the correction of a single deficiency may not be enough to improve growth substantially. OBJECTIVE: The objective was to evaluate the effect of multiple micronutrient supplementation on the growth of children aged 8-14 mo whose diets were poor in several micronutrients. DESIGN: Children were randomly assigned to 1 of 2 groups. One group received a multiple micronutrient supplement containing the recommended dietary allowance (RDA) or 1.5 times the RDA of vitamins A, D, E, K, C, B-1, B-6, B-12, riboflavin, niacin, biotin, folic acid, and pantothenic acid, and iron, zinc, iodine, copper, manganese, and selenium. The other group received a placebo. Supplements were administered 6 d/wk for an average of 12.2 mo. Body length was measured at baseline and monthly thereafter until the end of supplementation. RESULTS: Supplemented infants initially aged <12 mo had significantly greater length gains than did the placebo group, with a difference of 8.2 mm (length-for-age z score: 0.3) at the end of supplementation. In contrast, differences in length gains between the supplemented and placebo groups initially aged > or =12 mo were not significant. CONCLUSIONS: Micronutrient deficiencies limited the growth of the Mexican infants studied. Improving micronutrient intakes should be a component of interventions to promote growth in infants living in settings where micronutrient intakes are inadequate.

Age Factors↗
PubMed2001

Using a jail-based survey to monitor HIV and risk behaviors among Seattle area injection drug users.

Routine monitoring of human immunodeficiency virus (HIV) and risk behaviors among injection drug users (IDUs) is difficult outside drug treatment settings. We developed and implemented a survey of recently arrested IDUs to describe the prevalence of HIV, drug use, and sexual behaviors among them. A probability sampling survey was instituted in the King County Correctional Facility in Seattle, Washington, to sample recently arrested IDUs at the time of booking and in the jail health clinic between 1998 and 1999. Following HIV risk assessment and blood draw, additional information on drug use practices was gathered using a standardized questionnaire. Potential participants who were released from jail early could complete the study at a nearby research storefront office. Of the 4,344 persons intercepted at booking, 503 (12%) reported injection drug use, and 201 of the IDUs (40%) participated in the study. An additional 161 IDUs were enrolled in the study from the jail health clinic. Among the 348 unduplicated subjects, HIV prevalence was 2%; in the past 6 months, 69% reported two or more shooting partners, 72% used a cooker after someone else, 60% shared a syringe to divide up drugs, and 62% injected with used needles. Only 37% reported being hepatitis C seropositive, and 8% reported hepatitis B vaccination. It was feasible to conduct a jail-based survey of recently arrested IDUs that yielded useful information. The high prevalence of reported risky drug use practices warrants ongoing monitoring and illustrates the need for improving prevention programs for HIV and hepatitis B and C in this population, including expansion of hepatitis C screening and provision of hepatitis B vaccination at the jail health clinic.

Adolescent↗
PubMed2001

Expression of mosquito active toxin genes by a Colombian native strain of the gram-negative bacterium Asticcacaulis excentricus.

Mosquito control with biological insecticides, such as Bacillus sp. toxins, has been used widely in many countries. However, rapid sedimentation away from the mosquito larvae feeding zone causes a low residual effect. In order to overcome this problem, it has been proposed to clone the Bacillus toxin genes in aquatic bacteria which are able to live in the upper part of the water column. Two strains of Asticcacaulis excentricus were chosen to introduce the B. sphaericus binary toxin gene and B. thuringiensis subsp. medellin cry11Bb gene cloned in suitable vectors. In feeding experiments with these aquatic bacteria, it was shown that Culex quinquefasciatus, Aedes aegypti, and Anopheles albimanus larvae were able to survive on a diet based on this wild bacterium. A. excentricus recombinant strains were able to express both genes, but the recombinant strain expressing the B. sphaericus binary toxin was toxic to mosquito larvae. Crude protease A. excentricus extracts did not degrade the Cry11Bb toxin. The flotability studies indicated that the recombinant A. excentricus strains remained in the upper part of the water column longer than the wild type Bacillus strains.

Animals↗
PubMed2001

Restoration of a fractured primary incisor.

Esthetic restoration on primary teeth has been a special challenge to pediatric dentists. Composite restorations are the most often used treatment for decay and fractures of primary teeth, however, there are other possible alternatives. We present a case in which we have used an acrylic crown to treat a fractured primary incisor in a 1.8 years old child.

Acrylic Resins↗
PubMed2001

[Viral agents in patients with infectious processes of the central nervous system].

Local statistics report a great number of cases of neurological diseases of unidentified cause. The purpose of this research was to determine the presence of viral agents in patients with affection of the central nervous system, in Zulia State, Venezuela. In different health centers throughout the state, we collected 129 randomized samples of cerebrospinal fluid (CSF) and serum from patients ranging from 1 day to 41 years of age, showing symptoms of CNS disease and whose bacteriological test resulted negative. The serum/CSF albumin ratio was determined to exclude contaminated CSF samples, thus 54 optimal samples were obtained for the research. We determined serum IgM and CSF IgG specific for Venezuelan equine encephalomyelitis (VEE), Herpes simplex (HSV), Epstein Barr (EBV), Dengue, Rubella and Measles virus, through ELISA and indirect immunofluorescence techniques. Of the 54 samples studied, 33 (61.11%) were positive. %). The etiological agents implicated were VEE 14 cases (42.42%); HSV 11 cases (33.33%); EBV 5 cases (15.15%) and Dengue 3 cases (9.09%). We did not detect Rubella o Measles. Regarding the age distribution, the most affected group was that of children under 12 (83.34%). We analyzed the clinical manifestations and the CSF characteristics and did not find differences suggestive of an specific etiological diagnosis, even though certain signs could be considered early indications of CNS alterations due to viral causes. Our study shows that a large percentage of CNS affections of unknown etiology are produced by viral agents, indicating that in our region, most of this cases are not registered.

Antibodies, Viral↗
PubMed2000

Effect of thyroid hormones on mitochondrial oxygen free radical production and DNA oxidative damage in the rat heart.

Mitochondria seem to be involved in oxygen radical damage and aging. However, the possible relationships between oxygen consumption and oxygen radical production by functional mitochondria, and oxidative DNA damage, have not been studied previously. In order to analyze these relationships, male Wistar rats of 12 weeks of age were rendered hyper- and hypothyroid by chronic T(3) and 6-n-propyl-2-thiouracil treatments, respectively. Hypothyroidism decreased heart mitochondrial H(2)O(2) production in States 4 (to 51% of controls; P<0.05) and 3 (to 21% of controls; P<0.05). In agreement with this, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) decreased in the heart genomic DNA of hypothyroid animals to 40% of controls (P<0.001). Studies with respiratory inhibitors showed that the decrease in oxygen radical generation observed in hypothyroidism occurred at Complex III (mainly) and at Complex I; that decrease was due to the presence of a lower free radical leak in the respiratory chain (P<0.05). Hyperthyroidism did not significantly change heart mitochondrial H(2)O(2) production since the increase in State 4 oxygen consumption in comparison with control and hypothyroid animals (P<0.05) was compensated by a decrease in the free radical leak in relation to control animals (P<0.05). In agreement with this, heart 8-oxodG was not changed in hyperthyroid animals. The lack of increase in H(2)O(2) production per unit of mitochondrial protein will protect mitochondria themselves against self-inflicted damage during hyperthyroidism.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2000

Nitric oxide production and mitochondrial dysfunction during rat thymocyte apoptosis.

Production of nitric oxide (NO) by mitochondrial membranes as methemoglobin formation sensitive to N(G)-methyl-l-arginine inhibition and mitochondrial O(2) consumption in metabolic states 3 and 4 and the respiratory control (state 3/state 4) were measured at early stages of rat thymocyte apoptosis. Programmed cell death was induced by addition of methylprednisolone and etoposide to thymocyte suspensions. Increased NO production by mitochondrial membranes was observed after 30 min of methylprednisolone and etoposide addition and was accompanied by mitochondrial respiratory impairment as an early phenomenon in apoptotic thymocytes. The respiratory control in isolated mitochondria from untreated thymocytes was 4.2 +/- 0.2 and decreased to 3.1 +/- 0.2 and 1.9 +/- 0.3 after 1 h of methylprednisolone and etoposide treatment, respectively. The low mitochondrial respiratory control was accompanied by a marked decrease in GSH and cytochrome c content. Moreover, an inhibitory effect in the amount of apoptosis due to thymocyte pretreatment with N(G)-methyl-l-arginine and N(omega)-nitro-(l)-arginine (l-NNA), indicate that nitric oxide production is closely involved in the signaling of rat thymocyte apoptosis.

Animals↗
PubMed2000

Transcatheter occlusion of complex atrial septal defects.

Percutaneous device occlusion of secundum atrial septal defects (ASDs) is becoming an accepted alternative to surgical closure. This method allows us to evaluate patients with complex conditions for treatment. From a total of 70 patients with ASD evaluated for percutaneous closure, we selected for analysis 28 who had complex conditions. The mean age was 36+/-23 yr (range, 4-72). Six had heart failure, and of these six, three had atrial fibrillation. At cardiac catheterization, the pulmonary pressure was 47+/-24 mm Hg, and the QP/QS was 1.7+/-0.4; two patients had bidirectional shunt and systemic pulmonary pressure. Two patients received a buttoned device and 26 an Amplatzer septal occluder. The groups of patients with complex conditions were separated into the following groups. Group I (n = 4) underwent combined treatment of associated anomalies. Two patients had pulmonary stenosis, one had mitral stenosis, and one had an aortic root-left atrium fistula. They were treated in or during with the same procedure by combined transcatheter techniques (balloon valvuloplasty and fistula occlusion) before ASD occlusion. Group II (n = 9) had multiple defects (cribiform or two separate holes). They were treated with a single device in five instances and with two separate devices in four cases. Group III (n = 14) had large (32+/-3 mm) single defects. Nine of them underwent successful implantation using a device 33+/-3 mm in diameter; in the remaining five patients the device was removed because of instability. Group IV (n = 3) had residual defects after previous partial device occlusion. All three defects were successfully occluded with a second device. No movement or interference with the first device was observed. Group V (n = 6) had severe pulmonary hypertension (86+/-16 mm Hg). Immediately after ASD occlusion we observed significant relief in these patients (67+/-14 mm Hg; P<0.01). There were no major complications; all 23 patients with successful implants were discharged without symptoms 2-7 days later; one patient with atrial fibrillation recovered sinus rhythm. The follow-up (8+/-5 mo) Doppler echo study showed complete ASD occlusion in 22 patients and a peak pulmonary pressure of 30+/-14 mm Hg. We conclude that transcatheter occlusion of ASDs is an effective and safe treatment for patients with complex anatomic or physiopathologic conditions, as evaluated by short-term follow-up.

Adolescent↗
PubMed2000

Modulation of ICAM-1 tissue expression in patients with liver transplantation (LT) and acute rejection (AR) after glucocorticoid treatment.

Acute rejection (AR) is a frequent complication following liver transplantation (LT). ICAM-1 may be involved in its pathogenesis. High doses of glucocorticoids are the standard treatment in these patients. The aim of this study was to describe corticoid effects on ICAM-1 tissue expression in liver biopsies of patients with LT and AR. The study included liver biopsies performed before and after treatment in 12 patients with LT and proven AR. In 10 patients AR was reversible and in 2, was steroid resistant. For immunohistochemistry, an indirect immunoperoxidase technique was used. Each histology section was semiquantitatively evaluated as follows: 0: < 10% staining, 1: 10-25%, 2: 25-50%, 3: > 50%. The control group comprised nine patients with LT and normal liver biopsies. In pre-treatment liver biopsy samples, ICAM-1 was markedly expressed on sinusoidal cells (2.41 +/- 0.66), and there was also expression on periportal (0.66 +/- 0.65) and perivenular hepatocytes (0.83 +/- 0.57). By contrast, in the liver tissue from the control group, sinusoidal ICAM-1 reactivity was significantly lower (0.88 +/- 0.33; P < 0.05), and hepatocytes showed no reliable ICAM-1 expression. After steroid treatment the intensity of ICAM-1 decreased significantly in sinusoids (1.5 +/- 0.67; P < 0.05) and in perivenular hepatocytes (0.25 +/- 0.86; P < 0.05). Additionally, we also observed a decreased ICAM-1 reactivity in portal hepatocytes (0.25 +/- 0.62), but these differences did not reach statistical significance. Remarkably, after treatment, hepatocytes did not show ICAM-1 reactivity in resolved AR, but in corticoid-resistant patients AR did not change or increase. In conclusion, in patients with LT and AR, ICAM-1 was expressed in hepatocytes and with more intensity in sinusoid cells. Additionally, a down-regulation of the ICAM-1 tissue expression after corticoid treatment may exist, although in corticoid-resistant AR no modulation on ICAM-1 tissue expression was observed.

Acute Disease↗
PubMed2000

Renal tubular acidosis and vasculitis associated with IgE deposits in the kidney and small vessels.

We report a woman with a history of allergies, polyuria, polydipsia, proteinuria, renal loss of electrolytes, renal tubular acidosis, nephrocalcinosis, and palpable purpura. A proximal defect was excluded by a normal bicarbonate reabsorption curve, and a distal tubular defect was shown because urine pH did not decrease to less than 6.4 despite ammonium chloride-induced systemic acidosis. Moreover, furosemide failed to improve urinary acidification. Urine-to-blood PCO(2) gradient was less than 14 mm Hg, although the urine bicarbonate level reached values as high as 89 mEq/L. Combining bicarbonate and neutral phosphate infusions increased the urine-to-blood PCO(2) gradient to only 20 mm Hg. These subnormal PCO(2) gradient values point to proton-pump dysfunction in the collecting tubule. Histological evidence of tubulointerstitial disease accompanied the tubular defects. The striking histological feature was the presence of immunoglobulin E (IgE) deposits in glomeruli, tubuli, and vessels. Concurrent with these findings, she had high serum IgE titers and CD23 levels. IgE antibodies from her serum were reactive against human renal tubuli, with binding to two regions that matched two different proteins present in cortex and medulla. One of these proteins corresponded to carbonic anhydrase II (31 kd); the second, to an unidentified protein that seems attached to cell membranes. We suggest that these IgE antibodies could have had a pathogenic role in this patient's glomerular, tubular, and small-vessel disease.

Acidosis, Renal Tubular↗