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Biomedical subjects

M Vergara

Publications and source records attributed to M Vergara.

At least 37 records · Page 2Linked to original sources
PubMed1999

The impact of delaying gastric emptying by either meal substrate or drug on the [13C]-urea breath test.

OBJECTIVE: Optimal [13C]-urea breath test (UBT) conditions for diagnosis of Helicobacter pylori infection are still being fine-tuned. In the present study we investigated the impact of delaying gastric emptying by different meal substrates or L-DOPA, a drug known to induce gastric stasis, on the performance of the [13C]-UBT. METHODS: A total of 115 patients participated in the study. On two consecutive days, participants ingested [13C]-urea (100 mg) 10 min after either 270 ml of a mixed formula meal (1 Kcal/ml) or an equivalent amount of tap water. In 11 participants two additional tests were performed with or without oral 500 mg L-DOPA given 30 min before [13C]-urea load. The 13C/12C ratio in a basal breath sample was compared with ratios in samples collected 30 and 60 min after [13C]-urea. Histological assessment of H. pylori presence in antral biopsy served as reference standard. RESULTS: Formula UBT showed excellent specificity (100% at 30 and 60 min) and good sensitivity (97% at both time intervals), whereas water UBT had the same specificity but slightly lower sensitivity (94% at 30 min and 73% at 60 min). In formula UBT, 13C/12C ratios were higher at 60 min than at 30 min (21.7+/-2 vs 17.7+/-1.8 per thousand respectively, p < 0.01, whereas in water UBT 13C/12C ratios were higher at 30 min than at 60 min (13.9+/-1.5 vs 8.4+/-0.09 per thousand respectively, p < 0.01). Pretreatment with L-DOPA did not modify either the sensitivity or the specificity of the UBT. CONCLUSIONS: The performance of the [13C]-urea with a formula meal may not be improved by pharmacologically delaying gastric emptying. A short, water-based test may be a sensible approach to worldwide standardization of the [13C]-UBT for H. pylori infection.

Adult↗
PubMed1999

Prospective cohort study of enterotoxigenic Escherichia coli infections in Argentinean children.

In a follow-up study, enterotoxigenic Escherichia coli (ETEC) infections in 145 children from two communities located in northeastern Argentina were monitored for 2 years. The occurrence of diarrhea was monitored by weekly household visits. Of 730 fecal specimens collected, 137 (19%) corresponded to diarrheal episodes. ETEC was isolated from a significantly higher proportion of symptomatic (18.3%) than asymptomatic (13.3%) children (P = 0.04541). Individuals of up to 24 months of age were found to have a higher risk of developing ETEC diarrhea than older children (odds ratio [OR], 3.872; P = 0.00021). When the toxin profiles were considered, only heat stable enterotoxin (ST)-producing ETEC was directly associated with diarrhea (P = 0.00035). Fifty-five percent of the ETEC isolated from symptomatic children and 19% of the ETEC isolated from asymptomatic children expressed one of the colonization factors (CFs) investigated, i.e., CF antigen I (CFA/I), CFA/II, CFA/III, and CFA/IV; coli surface antigens CS7 and CS17; and putative CFs PCFO159, PCFO166, and PCFO20, indicating a clear association between diarrhea and ETEC strains that carry these factors (P = 0.0000034). The most frequently identified CFs were CFA/IV (16%), CFA/I (10%), and CS17 (9%). CFs were mostly associated with ETEC strains that produce ST and both heat-labile enterotoxin and ST. Logistic regression analysis, applied to remove confounding effects, revealed that the expression of CFs was associated with illness independently of the toxin type (OR, 4.81; P = 0.0003). When each CF was considered separately, CS17 was the only factor independently associated with illness (OR, 16.6; P = 0.0151). Most CFs (the exception was CFA/IV) fell within a limited array of serotypes, while the CF-negative isolates belonged to many different O:H types. These results demonstrate that some CFs are risk factors for the development of ETEC diarrhea.

Bacterial Proteins↗
PubMed1999

Impact of inflammatory bowel disease on health-related quality of life.

Health-related quality of life (HRQOL) has a recognized importance to evaluate, manage and follow patients. Different types of instruments for measuring HRQOL have recently been introduced to evaluate HRQOL in patients with inflammatory bowel disease. Most questionnaires suggest that inflammatory bowel disease has a significant impact in HRQOL. It seems that ulcerative colitis has less profound effects on HRQOL than Crohn's disease and that some differences in HRQOL status are related to some factors such as the severity of the disease. When patients express their concerns, most important worries are related to surgery. Effective medical treatment appears to improve HRQOL. Effects of surgery on HRQOL can probably be different depending on the type of surgical technique and if it is curative or not. Recent studies suggest that inflammatory bowel disease not only impacts on patient's HRQOL but also on their caregivers. Features such as the impact on HRQOL of different disease variables, such as complications or patient personality, the role of medical or surgical treatments on different dimensions of HRQOL, the cost-utility evaluation of therapy are some of the fields that will probably focus the protagonism in the next years.

Colitis, Ulcerative↗
PubMed1998

Diurnal changes in light intensity inside the pregnant uterus in sheep.

Penetration of light into the pregnant sheep uterus was studied in 9 ewes, gestational ages 40 to 142 days (term 147 days). Light sensors were placed inside the pregnant horn and over the flank skin overlying the position of the uterine horn. To perform the experiments, the ewes were placed in a study cage outdoors and light sensors were connected to a luxometer. Simultaneous measurements were obtained from the intrauterine and the external sensors in the shade at noon. The amount of light detected inside the uterus increased with gestational age from two lux at 40 days to 51.1 +/- 16.5 (n = 5) lux at 142 days (0.2 and 5.4% of the amount of light detected at the maternal flank). Measurements through the 24 h were done in four pregnant ewes at 142 days gestation under natural photoperiod (13.5 light:10.5 dark). In these experiments, the intensity of intrauterine light changed through the 24 h, reflecting the changes in the intensity of the sunlight. Maximal intrauterine light values were observed at noon, corresponding to 4.7% of incident light. Small but detectable values were observed at 0900 and 1800 h. Our data show that, at mid gestation, light reaches the pregnant uterus and that, at late gestation, changes in intrauterine lighting throughout the 24 h are present reflecting the changes in external daylight. Therefore the sheep fetus is exposed to light-dark transitions at dawn and dusk, and to a peak of light at midday.

Animals↗
PubMed1998

Changes in hypothalamic calmodulin concentration induced by perinatal hormone manipulation in the rat.

Calmodulin (CaM) presence and concentration was determined (RIA) in the rat hypothalamus (2, 6, 12, 24 h and 90 days after birth) in vehicle-treated animal (controls), in testosterone propionate (TP)-treated females (30 microg/rat subcutaneously 1 h after birth) and in tamoxifen-treated males (200 microg/rat subcutaneously 1 h after birth). CaM concentration, either as total content/hypothalamus or as concentration per mg ww, was significantly higher in both male and female adult rats than in newborn subjects. CaM concentration/mg protein increased with age, being two times higher in adult males and greater than three times higher in adult females than in their respective newborns. Two, 12, and 24 h after birth CaM concentration was significantly lower in control females than in control males. This relation was reversed in adults in which CaM concentration was higher in females. The application of TP to the females and tamoxifen to the males, induced a significant decrease in CaM/mg protein, both in the newborn (2 and 6 h) and in the adult animals. In adults, treated females had CaM concentrations similar to those found in control males. Our data suggest: first, a lasting effect of newborn hormonal treatment upon the CaM concentration in rat hypothalamus; second, that CaM is preferentially synthesized in the adult female hypothalamus, indicating an important role of this protein in female reproductive function.

Animals↗
PubMed1998

Acute pancreatitis as a triggering factor for thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura (TTP) constitutes a poorly understood multisystemic disease of vascular origin that may involve any organ by thrombotic occlusions of the small vessels. Treatment with plasmapheresis is the best therapeutic option at this present moment. Involvement of the pancreas is a well established feature of this disease, which has generally been interpreted as a consequence of pancreatic vascular compromise. However, there are a few cases in the literature in which the clinical signs of TTP developed well after the clinical and laboratory demonstration of acute pancreatitis (AP). Therefore, the possibility of pancreatic inflammation as a triggering factor of TTP may need to be considered. This cause-effect relationship between AP and TTP remains unclear. We report a patient with chronic pancreatitis presenting with two episodes of TTP, triggered by acute relapses of pancreatitis. TTP may, thus, constitute a hematological complication of AP. We discuss the pathophysiological aspects of this association, along with therapeutical options.

Acute Disease↗
PubMed1998

Influence of the smoking habit in the surgery of inflammatory bowel disease.

UNLABELLED: The smoking habit is a key factor in the development of inflammatory bowel disease (IBD), but little information exists as to the relationship between smoking habit, the need of surgery and its complications. OBJECTIVES: To investigate the relationship between smoking habit, the need of surgery, their complications and clinical recurrence after surgery in Crohn's disease (CD) and ulcerative colitis (UC). METHODS: We studied a group of 62 patients (22 with UC and 40 with CD) with previous surgery. We analyzed the clinical and surgical characteristics of the disease. Smoking habit was established by a personal interview. This group of patients was compared with another control group of 202 patients (133 with UC and 69 with CD) with IBD without previous surgery. RESULTS: Smoking habit was similar between operated and non-operated patients for both UC (73% and 80% non-smokers) and CD (67% and 63% smokers) The number and type of complications after surgery were not related with smoking habit. In CD patients, although the recurrences did not depend on the smoking habit, they did occur earlier in smokers than in non smokers (83.6 +/- 21 vs 155 +/- 50 weeks, p = ns). CONCLUSIONS: The smoking habit does not seem to influence significantly the need of surgery and post surgical development of IBD, although in CD the smokers seems to present recurrence before non smokers.

Adult↗
PubMed1997

Effects of smoking on the presentation and clinical course of inflammatory bowel disease.

OBJECTIVE: To evaluate the influence of regular smoking on the presentation and clinical course of inflammatory bowel disease. METHODS: We performed a case-control study interviewing 160 inflammatory bowel disease patients (63 with Crohn's disease (CD) and 97 with ulcerative colitis (UC)) and 140 first-degree relatives as controls. The risk of developing the disease relative to a smoking habit was calculated as the odds ratio. Furthermore, to evaluate the influence of smoking on the subsequent course of inflammatory bowel disease, we performed a multivariate analysis that included pertinent variables such as the need for surgery, number of hospitalizations and relapses. RESULTS: The pattern of smoking in UC patients was different from that in CD patients. In UC there was a significant predominance of non-smokers and ex-smokers (P = 0.02), whereas smoking habits in CD were not different from those in controls. Giving up smoking was a risk factor to develop UC (odds ratio: 3.2, P = 0.02). In UC, non-smokers and specially ex-smokers need surgery more frequently than smokers (P < 0.01). Otherwise the relapse/year index was not influenced by smoking. In CD there was a non-significant association between smoking habits and the various clinical parameters analysed. UC patients who begin smoking after diagnosis of the disease present a significant reduction in the number of recurrences. CONCLUSION: Smoking habit significantly affects the presentation and clinical course of UC, whereas in CD, a smoking habit does not have any apparent influence on the disease.

Adult↗
PubMed1997

Seasonal influence in exacerbations of inflammatory bowel disease.

Several epidemiological studies have suggested a possible seasonality in the presentation and course of inflammatory bowel disease. Our aim was to investigate whether in our area there is a seasonality in the presentation and evolution of inflammatory bowel disease. In this retrospective evaluation 255 patients were included, of whom 141 patients were diagnosed with ulcerative colitis and 114 with Crohn's disease according to conventional criteria, with histological confirmation in 225 patients. Relapse was defined as the development of symptoms that required an increase or change in the usual treatment. Periods of activity were related to the month and grouped within one of four seasonal periods: December to February, March to May, June to August and September to November. Bouts of ulcerative colitis and Crohn's disease were most frequently diagnosed in the period June to August (p < 0.05). Both diseases showed similar seasonality, and analysis of the 305 attacks did not show any significant trend. In conclusion, inflammatory bowel disease begins more frequently in the period June to August, but its course does not show consistent seasonal variations.

Adolescent↗
PubMed1997

Development of a radioimmunoassay for Cebus apella prolactin.

Prolactin (PRL) is a pituitary hormone that plays important roles in mammalian reproductive physiology, specially lactation. The regulation of PRL secretion shows important species differences. To study PRL regulation in a subhuman primate, the Cebus apella, we developed an heterologous radioimmunoassay using an antibody against rhesus PRL (anti-m5PRL) and a Cebus apella pituitary extract as PRL standard. The assay has a sensitivity that allows measurements of cebus PRL in small amounts of Cebus apella plasma obtained from animals in different physiological conditions. Plasma cebus PRL concentrations (+/-SEM) varied in different reproductive stages. PRL concentration in adult Cebus apella females that have regular menstrual cycles (161.6 +/- 15.0 mIU/ml) was similar to that found in adult (100.3 +/- 7.6 mIU/ml) and prepuberal males (101.2 +/- 3.9 mIU/ml). PRL concentration was higher in pregnant (677.8 +/- 11.8 mIU/ml) and in nursing (625.0 +/- 47.0 mIU/ml) Cebus apella females than in 15-d post-partum non-nursing (369.0 +/- 19.0 mIU/ml) and cycling females. PRL concentration in Cebus apella newborns (719.0 +/- 49.2 mIU/ ml) was similar to that found in pregnant and nursing females, and higher than in the other females as well as adult and prepuberal males. These differences in PRL concentration in different physiological conditions are similar to that observed in humans and other primates. A PRL response to thyrotropin releasing hormone (TRH) was demonstrated in 2 nursing Cebus apella females, similar to the response found in nursing woman and rhesus. Altogether, the data presented support the proposal that the assay developed to measure PRL in Cebus apella is an adequate tool to study the physiology of PRL in this species.

Animals↗
PubMed1997

[Toxigenic Vibrio cholerae: identification of the ctxB gene].

BACKGROUND: A specific probe was designed to identify part of the genetic sequence of the ctxB gene which encodes for the B subunit of the cholera toxin by polymerase chain reaction (PCR) which amplifies a 318 bp segment of the ctxB gene. Marked with P32, we used this probe for colony hybridization which is a technique for identifying the production capacity of subunit B of strains of Vibrio cholerae O1 from different outbreaks in South America (Perú 1992 and Ecuador 1993-1995) and from, collection strains. This probe was tested for the identification of the ctxB gene in Vibrio cholerae O139. METHOD: Thirty-eight phylogenetically related strains were studied: 24 V. cholerae O1, 4 V. cholerae non O1, 5 Aeromonas, 4 Plesiomonas and 1 Escherichia coli. RESULTS: The probe demonstrated to be useful for the identification of the ctxB gene (which codifies for the subunit B of the cholera toxin) in 24 strains of Vibrio cholerae O1 and in the Vibrio cholerae O139 strain. The ctxB gene was not detected in the remaining strains pertaining to the Vibrio cholerae non O1 species (non O139), Plesiomonas, Aeromonas spp. and E. coli. The specificity of this product was not demonstrated since no signal of unspecific hybridization appeared with phylogenetically related strains such as Escherichia coli K88 (LT+) and Aeromonas hydrophila ATCC (LT+), producers of the thermolabile LT toxin. It is important to indicate that the ctxB gene in V. cholerae O139 has been identified, for the first time, with our probe and thus it may be said that all the strains which have genetic codification for CT up to now may be identified. CONCLUSIONS: We conclude that the system herein described provides advantages over the immunologic and biologic methods for evaluating a large number of samples in a short time and with excellent specificity and sensitivity which are important in the diagnosis and the epidemiologic surveillance of the disease.

Aeromonas↗
PubMed1996

Adverse reactions to contrast media in CT: effects of temperature and ionic property.

PURPOSE: To assess the severity of adverse reactions to contrast media in outpatient computed tomographic (CT) examinations in a conventional clinical setting. MATERIALS AND METHODS: In 4,936 patients, CT was performed with four protocols: ionic contrast medium with sodium meglumine as the cation (in one protocol, contrast material was warmed to 35 degrees C before injection; in another protocol, it was administered at ambient temperature); warmed, ionic contrast medium with nonsodium pure meglumine as the cation; and warmed, nonionic iopamidol. RESULTS: Adverse reactions to ionic contrast material statistically significantly decreased (P<.05) when it was warmed before administration. Reactions to ionic contrast media without a sodium cation were statistically significantly fewer (P<.001) than reactions to those with a sodium cation. In all protocols, pediatric patients had fewer reactions than adult patients. CONCLUSION: In outpatient CT examinations, nonionic, warmed contrast medium was the best option because no severe reactions resulted from its use. Prevalence of adverse reactions was comparable to that in controlled randomized studies.

Adult↗
PubMed1996

Effect of constant light on fetal and maternal prolactin rhythms in sheep.

A 24-h rhythm of plasma PRL is present in fetal sheep. This rhythm is synchronized to an environmental clue (zeitgeber). We determined whether the light-dark cycle (L:D) is a zeitgeber for the fetal PRL rhythm and, if so, whether the mother might convey this zeitgeber to the fetus. We kept nine ewes (twin pregnancies) in constant light (L:L) and five ewes (singleton) in 14:10 L:D from 110 days gestation. Fetuses and mothers were catheterized at 119 days gestation. Blood samples were taken hourly for 24 h after 16 days under L:L or L:D. A mean 24-h rhythm of PRL was found (by RIA) in fetuses under L:D, but not in those under L:L. However, fetuses under L:L showed individual 24-h PRL rhythms (cosinor analysis) whose acrophases were distributed around the clock. Nonsynchronized rhythms persisted after 23 and 30 days of L:L. Acrophases of PRL rhythms within a set of twins were closer than those between sets, suggesting that twins were responding to a common signal. These findings indicate that the L:D cycle is a zeitgeber for the PRL rhythm in fetal sheep and suggest that the mother might convey the zeitgeber.

Animals↗
PubMed1996

[Changes in the epidemiology of gastric cancer in the last 15 years].

AIM: To determine whether the epidemiological profile of gastric cancer is changing in our patient referral area. EXPERIMENTAL DESIGN: We have compared the incidence rates of gastric cancer in our Hospital in two three year periods (1975 to 1977 and 1990 to 1992). Gastric cancer was diagnosed by endoscopy or surgery and confirmed histologically. Incidence rate was obtained calculating the ratio (cases of gastric cancer)/ (patients assisted at the hospital) for each period. RESULTS: 522 patients were identified in the first period, and only 255 in the second. Then, the overall incidence fell from 96 x 10(5) to 37 x 10(5). In both periods a male predominance, with a sex ratio male/ female of 1.9 in the first period and 1.6 in the second, was observed. The mean age was also similar in both periods: 61 years (range 20-89) and 65.5 (range 28-90) respectively. Adenocarcinoma was the predominant neoplasm in both periods (98% and 95% respectively). There was also a predominance of antral tumors with a slight decrease of their incidence in the later series (ratio antrum/other gastric sites) from 1.6 to 1.1 respectively (p = 0.07). CONCLUSIONS: Although gastric cancer is still very common, its incidence in our referral area is decreasing. In addition, the characteristic antral predominance also seems to be decreasing. It remains to be established whether the changing pattern we have observed is related to environmental variation.

Adenocarcinoma↗
PubMed1996

[Acute pancreatitis in cystic fibrosis].

Cystic fibrosis is the most prevalent hereditary disease in the Caucasian race. It is a multisystemic alteration that affects the quality and quantitative properties of exocrine secretions. The pancreas develops a progressive atrophy causing steatorrhoea and nutritive deficiencies. Acute pancreatitis is an unusual complication. The pancreatic atrophy prevents the inflammatory response. Published series suggest that pancreatitis in 0.5%, including patients without pancreatic insufficiency. We present two cases with cystic fibrosis, with and without pancreatic insufficiency, who developed acute pancreatitis.

Acute Disease↗
PubMed1995

Antibody responses against Escherichia coli heat-labile toxin and colonization factor antigens I and II in Argentinian children.

Serum antibody responses against Escherichia coli heat-labile enterotoxin (LT) and colonization factor antigens (CFAs) I and II were studied in 84 children < 5 years old living in two communities. These villages differed in the quality of their drinking water. Children from both communities developed significantly increased antibody titers against LT and CFA/II but not against CFA/I during 3 months of follow-up. The magnitude of the anti-LT response was significantly higher in children from Zaiman than in those from Las Dolores. Antibody titers rose to maximum levels during the second year of age and reached relatively constant levels in children aged 2-5 years, probably due to repeated exposure to enterotoxigenic E. coli strains. Antibody levels of 30 children were followed for 2 years; increases in anti-LT and anti-CFA titers varied in the different age groups.

Age Factors↗
PubMed1995

Diminished luteinizing hormone biopotency in breastfeeding women.

The effect of nursing on plasma luteinizing hormone bioactivity (B-LH) and immunoactivity (I-LH) was assessed at 4 and 6 months post partum in fully nursing women who experienced their first bleeding between months 5 and 6 post partum (n = 6, short amenorrhoea) or after the month 6 (n = 10, long amenorrhoea). Controls were 10 non-nursing fertile women. Blood samples were drawn twice weekly at month 4 post partum and at month 6 post partum. In the nursing women who were cycling at month 6 and in non-nursing women samples were drawn during the follicular phase. I-LH was measured by a time resolved immunofluorometric assay (DELFIA) and B-LH by the mouse Leydig cell assay. Nursing decreased B-LH more than I-LH resulting in a relationship between B-LH and I-LH different to that of non-nursing women (B-LH = 2.84 x I-LH-0.16 and B-LH = 4.27 x I-LH + 3.11 respectively, P < 0.05, by likelihood test). Plasma B-LH or I-LH were similar in nursing women with short or long amenorrhoea. In conclusion, nursing alters the quality of circulating LH, however, the decreased LH steroidogenic potency does not play a role in determining the duration of lactational amenorrhoea.

Adult↗