In silico integrative analysis for the characterization of LYT1 a unique protein of Trypanosoma cruzi

Trypanosoma rangeli is the most similar organism to Trypanosoma cruzi. They share distribution areas, hosts, and some vectors. However, there are key differences between them; the first lacks a multiplicative form in the host and does not cause disease, while the second is the etiological agent of the American tripanosomiasis, a tropical disease that still does not have an effective vaccine nor treatment. Aiming to reveal the differences in their gene expression patterns in each life cycle form, the comparison of expression profiles was made parting from the ESTs available in TriTrypDB. We verified that there are no genes unique to T. rangeli in the ESTs. Astonishingly, we determined that T. cruzi has a single copy gene called LYT1, which has no similarity to any other protein of any organism on Earth. LYT1 is involved in invasion, motility, and cell cycle, making it an attractive vaccine target. After its identification, using immunoinformatics programs, we found multiple potential B- and T-cell epitopes in this protein, which is also rich in intrinsically disordered regions. Additionally, an approximation of the 3 D structure was predicted where the B-cell epitopes were located to assess their solvent access. We propose that its particular structural conformation confers the flexibility required for the interactions with multiple proteins, which in part may be performed through N-myristoylation sites. Given its important role in the infectiveness of T. cruzi and its antigenic potential, we highlight the need for future studies focused on its molecular and immunological in vivo characterization.Communicated by Ramaswamy H. Sarma.

A variation in the infant oxytocin receptor gene modulates infant hippocampal volumes in association with sex and prenatal maternal anxiety

Genetic variants in the oxytocin receptor (OTR) have been linked to distinct social phenotypes, psychiatric disorders and brain volume alterations in adults. However, to date, it is unknown how OTR genotype shapes prenatal brain development and whether it interacts with maternal prenatal environmental risk factors on infant brain volumes. In 105 Finnish mother-infant dyads (44 female, 11-54 days old), the association of offspring OTR genotype rs53576 and its interaction with prenatal maternal anxiety (revised Symptom Checklist 90, gestational weeks 14, 24, 34) on infant bilateral amygdalar, hippocampal and caudate volumes were probed. A sex-specific main effect of rs53576 on infant left hippocampal volumes was observed. In boys compared to girls, left hippocampal volumes were significantly larger in GG-homozygotes compared to A-allele carriers. Furthermore, genotype rs53576 and prenatal maternal anxiety significantly interacted on right hippocampal volumes irrespective of sex. Higher maternal anxiety was associated both with larger hippocampal volumes in A-allele carriers than GG-homozygotes, and, though statistically weak, also with smaller right caudate volumes in GG-homozygotes than A-allele carriers. Our study results suggest that OTR genotype enhances hippocampal neurogenesis in male GG-homozygotes. Further, prenatal maternal anxiety might induce brain alterations that render GG-homozygotes compared to A-allele carriers more vulnerable to depression.

Partial Support for an Interaction Between a Polygenic Risk Score for Major Depressive Disorder and Prenatal Maternal Depressive Symptoms on Infant Right Amygdalar Volumes

Psychiatric disease susceptibility partly originates prenatally and is shaped by an interplay of genetic and environmental risk factors. A recent study has provided preliminary evidence that an offspring polygenic risk score for major depressive disorder (PRS-MDD), based on European ancestry, interacts with prenatal maternal depressive symptoms (GxE) on neonatal right amygdalar (US and Asian cohort) and hippocampal volumes (Asian cohort). However, to date, this GxE interplay has only been addressed by one study and is yet unknown for a European ancestry sample. We investigated in 105 Finnish mother-infant dyads (44 female, 11-54 days old) how offspring PRS-MDD interacts with prenatal maternal depressive symptoms (Edinburgh Postnatal Depression Scale, gestational weeks 14, 24, 34) on infant amygdalar and hippocampal volumes. We found a GxE effect on right amygdalar volumes, significant in the main analysis, but nonsignificant after multiple comparison correction and some of the control analyses, whose direction paralleled the US cohort findings. Additional exploratory analyses suggested a sex-specific GxE effect on right hippocampal volumes. Our study is the first to provide support, though statistically weak, for an interplay of offspring PRS-MDD and prenatal maternal depressive symptoms on infant limbic brain volumes in a cohort matched to the PRS-MDD discovery sample.

Structure, Properties, and Function of Glycosomes in Trypanosoma cruzi

Glycosomes are peroxisome-related organelles that have been identified in kinetoplastids and diplonemids. The hallmark of glycosomes is their harboring of the majority of the glycolytic enzymes. Our biochemical studies and proteome analysis of Trypanosoma cruzi glycosomes have located, in addition to enzymes of the glycolytic pathway, enzymes of several other metabolic processes in the organelles. These analyses revealed many aspects in common with glycosomes from other trypanosomatids as well as features that seem specific for T. cruzi. Their enzyme content indicates that T. cruzi glycosomes are multifunctional organelles, involved in both several catabolic processes such as glycolysis and anabolic ones. Specifically discussed in this minireview are the cross-talk between glycosomal metabolism and metabolic processes occurring in other cell compartments, and the importance of metabolite translocation systems in the glycosomal membrane to enable the coordination between the spatially separated processes. Possible mechanisms for metabolite translocation across the membrane are suggested by proteins identified in the organelle's membrane-homologs of the ABC and MCF transporter families-and the presence of channels as inferred previously from the detection of channel-forming proteins in glycosomal membrane preparations from the related parasite T. brucei. Together, these data provide insight in the way in which different parts of T. cruzi metabolism, although uniquely distributed over different compartments, are integrated and regulated. Moreover, this information reveals opportunities for the development of drugs against Chagas disease caused by these parasites and for which currently no adequate treatment is available.

Isolation of Glycosomes from Trypanosoma cruzi

Glycosomes are peroxisome-related organelles of trypanosomatids in which the glycolytic and some other metabolic pathways are compartmentalized. We describe here two methods for the purification of glycosomes from Trypanosoma cruzi for preparative purposes, differential and isopycnic centrifugation. These are two techniques that allow the separation of different cellular compartments based on their different physicochemical characteristics. The first type of centrifugation is a rapid method that does not require large inputs and allows for fractions enriched in specific cell compartments to be obtained. The second type of centrifugation is a more elaborate method, but enables highly purified cellular compartments to be isolated. The success in obtaining these purified, intact organelles critically depends on using an appropriate method for controlled rupture of the cells.

P575Merging technologies to provide Mexico an innovative nationwide AMI management network

Background

“Cόdigo Infarto”, the vast patient-centric, app-based, educational crusade of the Mexican Society of Interventional Cardiology (SOCIME) has been combined with the Latin America Telemedicine Infarct Network (LATIN) to create a comprehensive, national AMI program for Mexico.

Purpose

To demonstrate the benefits of amalgamating educational initiatives of national cardiology societies with a global telemedicine program for improving AMI management.

Methods

“Cόdigo Infarto” App connects patients to a network of several hundred cardiologists and 250 Primary PCI-capable labs. LATIN provides the partnership with its robust telemedicine platform, a hub-spoke strategy that supports patient's access to appropriate medical management. Remotely located experts, in Colombia, provide urgent EKG diagnosis via tele-consultation to the entire LATIN Mexico network. They activate ambulance dispatch and implement guideline-based protocols.

Results

Numerous “Cόdigo Infarto” sites have incorporated LATIN to provide a simple and accelerated management of AMI patients. Currently, the partnership (7 hubs, 78 spokes) has screened 19,886 patients. A total of 359 STEMI cases (1.8%) have been diagnosed; 118 patients (33%) were urgently reperfused, Primary PCI was performed in 74% of the latter cases. D2B time was 41 min. Reasons for the lack of treatment include delayed presentation, lack of ICU beds and insurance denials. Currently, these constraints are being methodically probed. Updated results will be available at time of presentation.

Conclusions

The synergy of the AMI initiative for Mexico provides a template for similar initiatives in developing countries.

Proteomic analysis of glycosomes from Trypanosoma cruzi epimastigotes

In Trypanosoma cruzi, the causal agent of Chagas disease, the first seven steps of glycolysis are compartmentalized in glycosomes, which are authentic but specialized peroxisomes. Besides glycolysis, activity of enzymes of other metabolic processes have been reported to be present in glycosomes, such as β-oxidation of fatty acids, purine salvage, pentose-phosphate pathway, gluconeogenesis and biosynthesis of ether-lipids, isoprenoids, sterols and pyrimidines. In this study, we have purified glycosomes from T. cruzi epimastigotes, collected the soluble and membrane fractions of these organelles, and separated peripheral and integral membrane proteins by Na₂CO₃ treatment and osmotic shock. Proteomic analysis was performed on each of these fractions, allowing us to confirm the presence of enzymes involved in various metabolic pathways as well as identify new components of this parasite's glycosomes.

Schizotypy and mentalizing: An fMRI study

INTRODUCTION

Schizotypy is a personality trait characterized by subclinical schizophrenia symptoms. Individuals with schizophrenia typically display behavioral mentalizing deficits and altered neural correlates during mentalizing. While schizotypy has been inconsistently related to behavioral mentalizing skills, its neural correlates of mentalizing are understudied so far. With this study we tested the association between schizotypy traits in healthy subjects and mentalizing-related neural correlates to provide new insights into neural processes associated with subclinical schizophrenia traits.

METHODS

Brain activation was measured using fMRI during an interactive mentalizing paradigm (Prisoner's Dilemma Game) in 164 healthy subjects. The Schizotypal Personality Questionnaire (SPQ-B) was administered to assess the three dimensions of schizotypy, i.e., cognitive-perceptual, interpersonal and disorganized.

RESULTS

We found that interpersonal schizotypy was significantly negatively correlated with brain activation in bilateral precunei and right caudate nucleus (among others) during mentalizing. By contrast, disorganized schizotypy was significantly positively correlated with mentalizing-associated neural activation in right precuneus, left middle cingulate cortex and right cerebellar hemisphere. No significant associations for cognitive-perceptual schizotypy and the SPQ-B total score were found.

DISCUSSION

Our study showed that interpersonal and disorganized schizotypy are associated with neural correlates of mentalizing in brain regions that are involved in self-processing and mentalizing. These brain regions have also been linked to mentalizing in schizophrenia.

Subcellular localization of glycolytic enzymes and characterization of intermediary metabolism of Trypanosoma rangeli

Trypanosoma rangeli is a hemoflagellate protist that infects wild and domestic mammals as well as humans in Central and South America. Although this parasite is not pathogenic for human, it is being studied because it shares with Trypanosoma cruzi, the etiological agent of Chagas' disease, biological characteristics, geographic distribution, vectors and vertebrate hosts. Several metabolic studies have been performed with T. cruzi epimastigotes, however little is known about the metabolism of T. rangeli. In this work we present the subcellular distribution of the T. rangeli enzymes responsible for the conversion of glucose to pyruvate, as determined by epifluorescense immunomicroscopy and subcellular fractionation involving either selective membrane permeabilization with digitonin or differential and isopycnic centrifugation. We found that in T. rangeli epimastigotes the first six enzymes of the glycolytic pathway, involved in the conversion of glucose to 1,3-bisphosphoglycerate are located within glycosomes, while the last four steps occur in the cytosol. In contrast with T. cruzi, where three isoenzymes (one cytosolic and two glycosomal) of phosphoglycerate kinase are expressed simultaneously, only one enzyme with this activity is detected in T. rangeli epimastigotes, in the cytosol. Consistent with this latter result, we found enzymes involved in auxiliary pathways to glycolysis needed to maintain adenine nucleotide and redox balances within glycosomes such as phosphoenolpyruvate carboxykinase, malate dehydrogenase, fumarate reductase, pyruvate phosphate dikinase and glycerol-3-phosphate dehydrogenase. Glucokinase, galactokinase and the first enzyme of the pentose-phosphate pathway, glucose-6-phosphate dehydrogenase, were also located inside glycosomes. Furthermore, we demonstrate that T. rangeli epimastigotes growing in LIT medium only consume glucose and do not excrete ammonium; moreover, they are unable to survive in partially-depleted glucose medium. The velocity of glucose consumption is about 40% higher than that of procyclic Trypanosoma brucei, and four times faster than by T. cruzi epimastigotes under the same culture conditions.

Kinetic and molecular characterization of the pyruvate phosphate dikinase from Trypanosoma cruzi

Trypanosoma cruzi, like other trypanosomatids analyzed so far, can use both glucose and amino acids as carbon and energy source. In these parasites, glycolysis is compartmentalized in glycosomes, authentic but specialized peroxisomes. The major part of this pathway, as well as a two-branched glycolytic auxiliary system, are present in these organelles. The first enzyme of one branch of this auxiliary system is the PPi-dependent pyruvate phosphate dikinase (PPDK) that converts phosphoenolpyruvate (PEP), inorganic pyrophosphate (PPi) and AMP into pyruvate, inorganic phosphate (Pi) and ATP, thus contributing to the ATP/ADP balance within the glycosomes. In this work we cloned, expressed and purified the T. cruzi PPDK. It kinetic parameters were determined, finding KM values for PEP, PPi and AMP of 320, 70 and 17 μM, respectively. Using molecular exclusion chromatography, two native forms of the enzyme were found with estimated molecular weights of 200 and 100 kDa, corresponding to a homodimer and monomer, respectively. It was established that T. cruzi PPDK's specific activity can be enhanced up to 2.6 times by the presence of ammonium in the assay mixture. During growth of epimastigotes in batch culture an apparent decrease in the specific activity of PPDK was observed. However, when its activity is normalized for the presence of ammonium in the medium, no significant modification of the enzyme activity per cell in time was found.

Hysteresis and positive cooperativity as possible regulatory mechanisms of Trypanosoma cruzi hexokinase activity

In Trypanosoma cruzi, the causal agent of Chagas disease, the first six or seven steps of glycolysis are compartmentalized in glycosomes, which are authentic but specialized peroxisomes. Hexokinase (HK), the first enzyme in the glycolytic pathway, has been an important research object, particularly as a potential drug target. Here we present the results of a specific kinetics study of the native HK from T. cruzi epimastigotes; a sigmoidal behavior was apparent when the velocity of the reaction was determined as a function of the concentration of its substrates, glucose and ATP. This behavior was only observed at low enzyme concentration, while at high concentration classical Michaelis-Menten kinetics was displayed. The progress curve of the enzyme's activity displays a lag phase of which the length is dependent on the protein concentration, suggesting that HK is a hysteretic enzyme. The hysteretic behavior may be attributed to slow changes in the conformation of T. cruzi HK as a response to variations of glucose and ATP concentrations in the glycosomal matrix. Variations in HK's substrate concentrations within the glycosomes may be due to variations in the trypanosome's environment. The hysteretic and cooperative behavior of the enzyme may be a form of regulation by which the parasite can more readily adapt to these environmental changes, occurring within each of its hosts, or during the early phase of transition to a new host.

Acute febrile illness surveillance in a tertiary hospital emergency department: comparison of influenza and dengue virus infections

In 2009, an increased proportion of suspected dengue cases reported to the surveillance system in Puerto Rico were laboratory negative. As a result, enhanced acute febrile illness (AFI) surveillance was initiated in a tertiary care hospital. Patients with fever of unknown origin for 2-7 days duration were tested for Leptospira, enteroviruses, influenza, and dengue virus. Among the 284 enrolled patients, 31 dengue, 136 influenza, and 3 enterovirus cases were confirmed. Nearly half (48%) of the confirmed dengue cases met clinical criteria for influenza. Dengue patients were more likely than influenza patients to have hemorrhage (81% versus 26%), rash (39% versus 9%), and a positive tourniquet test (52% versus 18%). Mean platelet and white blood cell count were lower among dengue patients. Clinical diagnosis can be particularly difficult when outbreaks of other AFI occur during dengue season. A complete blood count and tourniquet test may be useful to differentiate dengue from other AFIs.

Pyruvate phosphate dikinase and pyrophosphate metabolism in the glycosome of Trypanosoma cruzi epimastigotes

Pyruvate phosphate dikinase (PPDK) was recently reported in trypanosomatids, but its metabolic function is not yet known. The present work deals with the cellular localization and the function of the Trypanosoma cruzi enzyme. First, we show by digitonin titration and cell fractionation that the enzyme was essentially present in the glycosome matrix of the epimastigote form. Second, we address the issue of the direction of the reaction inside the glycosome for one part, our bibliographic survey evidenced a quite exergonic DeltaGo' (at least -5.2 kcal/mol at neutral pH and physiologic ionic strength); for another part, no pyrophosphatase (PPase) could be detected in fractions corresponding to the glycosomes; therefore, glycosomal PPDK likely works in the direction of pyruvate production. Third, we address the issue of the origin of the glycosomal pyrophosphate (PPi): several synthetic pathways known to produce PPi are already considered to be glycosomal. This work also indicates the presence of an NADP(+)-dependent beta-oxidation of palmitoyl-CoA in the glycosome. Several pyruvate-consuming activities, in particular alanine dehydrogenase (ADH) and pyruvate carboxylase (PC), were detected in the glycosomal fraction. PPDK appears therefore as a central enzyme in the metabolism of the glycosome of T. cruzi by providing a link between glycolysis, fatty acid oxidation and biosynthetic PPi-producing pathways. Indeed, PPDK seems to replace pyrophosphatase in its classical thermodynamic role of displacing the equilibrium of PPi-producing reactions, as well as in its role of eliminating the toxic PPi.

Influenza vaccination of patients with systemic lupus erythematosus

OBJECTIVE

To determine the safety, the immunogenicity, and the increase of pre-existing autoantibodies in patients with systemic lupus erythematosus (SLE) following influenza vaccination.

PATIENTS AND METHODS

Eighteen women with SLE received an inactivated influenza vaccine. Antibody titers were measured before and 4 weeks after vaccination using a standardized hemagglutination inhibition (HAI) assay. Disease activity and antinuclear autoantibodies were determined at study entry, at 4 weeks, and at 8 weeks after vaccination.

RESULTS

After vaccination, the percentage of patients with anti-hemagglutinin antibody levels increased significantly but was lower than in healthy women. Mean antibody titer of patients increased significantly but also was lower than that of controls. Both the mean of disease activity and anti-ds DNA antibody decreased significantly. Adverse effects to the vaccine were mild.

CONCLUSIONS

a) Influenza vaccination appears to be safe; b). Antibody response to influenza vaccination increases significantly for all 3 influenza antigens; c) Specific antibody response is not significantly affected by treatment, age, IgG levels, or disease activity.

Seroprevalence of Schistosoma mansoni in Puerto Ricans with inflammatory bowel disease

BACKGROUND

The etiology of Inflammatory Bowel Diseases, Crohn's disease (CD) and ulcerative colitis (UC), is unknown. These diseases have a higher incidence in industrialized countries and their pathogenesis involves an over-reaction of the immune system. A genetic factor is believed to predispose to the development of chronic inflammation in response to an unidentified stimulus. Exposure to infections in childhood may modulate future immune responses. Parasitosis, particularly Schistosomiasis, stimulate Th2 immune responses. It has been hypothesized that the absence of these parasitic infections, as seen in economically developed countries, favors a Th1 response that may result in the clinical appearance of Crohn's disease later in life.

OBJECTIVE

To determine the prevalence of Schistosoma mansoni antibodies in Puerto Ricans with Inflammatory Bowel Disease and controls.

METHODS

Serum from 92 Puerto Ricans with IBD and 106 controls was screened for S. mansoni adult microsomal antigens (MAMA) using the FAST:ELISA assay. Those positive were confirmed with an enzyme-linked immunoelectrotransfer blot test.

RESULTS

Seven serum samples (3 UC and 4 controls) were positive for S. mansoni antibodies. There was no significant difference between groups in gender, municipality of origin or seroprevalence of Schistosomiasis. The control group was slightly older than the IBD group.

CONCLUSIONS

Our study did not demonstrate an inverse relation between Schistosomiasis and IBD. However, the decreasing prevalence of Schistosomiasis in the general population of Puerto Rico may account for this result.

A alpha-glycerophosphate dehydrogenase is present in Trypanosoma cruzi glycosomes

alpha-glycerophosphate dehydrogenase (alpha-GPDH-EC.1.1.1.8) has been considered absent in Trypanosoma cruzi in contradiction with all other studied trypanosomatids. After observing that the sole malate dehydrogenase can not maintain the intraglycosomal redox balance, GPDH activity was looked for and found, although in very variable levels, in epimastigotes extracts. GPDH was shown to be exclusively located in the glycosome of T. cruzi by digitonin treatment and isopycnic centrifugation. Antibody against T. brucei GPDH showed that this enzyme seemed to be present in an essentially inactive form at the beginning of the epimastigotes growth. GPDH is apparently linked to a salicylhydroxmic-sensitive glycerophosphate reoxidizing system and plays an essential role in the glycosome redox balance.

[Treatment with tuberculostatic drugs: compliance at a general hospital]

The purpose of this study was to assess the compliance with tuberculostatic drugs treatment in a public hospital from Córdoba City and to establish the causes of noncompliance. All the patients to which treatment with tuberculostatic drugs was indicated from January 1991 up to December 1994 were included. 45 patients were included: 18 females (40%) and 29 males. Sixteen (35.6%) did not complete the time of treatment indicated. Nine (56.3%) abandoned the treatment 2 months after having initiated it. In the group that did not complete the treatment there was a higher percentage of female patients (62.5%) than in the group that did complete it (27.6%), p = 0.02. There were not statistically significant differences in age, percentages of pulmonar and extrapulmonar tuberculosis and months of treatment indicated between both groups. Thirty-six percent of the patients who abandoned the treatment referred having interrupted it due to their own negligency, knowing the risk of such behavior; 36% suffered side effects and did not come back to hospital; 21% referred having consulted another physician who indicated to interrupt the treatment without performing other tests; and 7% misunderstood the indications. It is concluded that in a general hospital from Córdoba City, the percentage of patients who abandoned tuberculostatic treatment is high. In most cases the cause was related to failures in the conduct of patients, physicians or both.

[Clinical and epidemiologic characteristics of acute diarrhea in adults at a hospital from Cordoba city]

The purpose of this work was to assess the clinical and epidemiologic presentation features of adult acute diarrhea in a general hospital form Córdoba City. All the patients older than 14 years old who assisted to the Hospital Nacional de Clínicas Central Guard for acute diarrhea, during the periods: A (15-12-89 to 15-03-90), B (15-12-93 to 15-03-94) and C (15-12-94 to 15-03-95), were included. 594 patients were studied: 337 female (56.7%) and 257 male, 143 in the period A, 250 in B and 201 in C. The means +/- SD age was 34.6 +/- 13.3 and stool loose per day at admission 7.3 +/- 4.7. Eighty six percent of patients presented liquid consistent stool, 89.6% abdominal pain, 44.7% vomiting and 18.8% bloody stools. The rate of patients who consulted Central Guard referring acute diarrhea increased from period A (2.4%) to B (3.61%); p = 0.002 and decreased form B to C (2.85%); p = 0.01. The mean (+/- SD) days transcurred from the beginning of diarrhea episode till consultation was 3.5 +/- 2.7; 2.7 +/- 2.3 y 2.9 +/- 3.5 in the periods A, B and C respectively, statistically significant difference between A and B, p < 0.01. Thirty six percent, 21.1% and 23.1% of patients presented mucus with their stools in the periods A, B and C (p = 0.01), and high temperature 61.1%, 48.1% and 48.5% respectively (p = 0.04). Twenty seven percent of stools samples cultures became positive in the periods A, 17.6% in B and 11.5% in C, statistically significant difference between A and C; p = 0.008. The results show that in a general hospital from Córdoba City the adult acute diarrhea is a frequent cause of consult. In the last years there were modifications in its clinical an epidemiologic presentation features.

Heart rate variability in inappropriate sinus tachycardia

Analysis of heart rate variability in patients with inappropriate sinus tachycardia showed a 24-hour decrease in all temporal and spectral indexes, even after attempted correction to a rate of 75 beats/min. This may have resulted from a global decrease in parasympathetic activity or from a rapid sinus rate produced by other ill-defined mechanisms.

Sudden Wenckebach periods and their relationship to neurocardiogenic syncope

Throughout a 9-month period during which 1,125 Holter tapes were reviewed prospectively we identified 13 nonmedicated patients with an arrhythmia, which for the purposes of this presentation was categorized, because of their mode of initiation, as sudden Wenckebach periods (WP). The episodes emerged abruptly from a normal (< or = 200 ms) PR interval with sudden prolongation of PR and PP intervals (and reversed PR-RP relationship) that took place over 1-8 cycles. The postpaced PR interval was shorter than that of the last conducted beat. The episodes were separated into two groups. Group I included 11 patients with symptoms other than syncope and Group II included 2 patients with syncope. There were 26 episodes of sudden WP in Group I. Twenty-five terminated in a single (and one in double) blocked P waves. Most episodes occurred between 10 PM and 7 AM. Symptoms did not correlate with the episodes. Mean 24-hour rates were < 90. In Group II there were 22 episodes, all occurring between 6 AM and 10 PM. The mean sinus cycle lengths before the phenomenon started to occur in Group I (861 +/- 185 ms) as well as the cycle lengths at the onset of block (1,096 +/- 215 ms) were statistically longer than those in Group II (591 +/- 40 ms and 747 +/- 63 ms, respectively, P < 0.0001). Although the mode of onset in the episodes in Group II was similar to Group I, 16 episodes terminated in 2-6 blocked P waves. Thus, the entire number of episodes could be categorized as an unusual type (because of the PR prolongation) of paroxysmal, or advanced second degree AV block. Because these patients had negative electrophysiological studies, positive tilt tests, and absent syncope after oral propranolol therapy, they were considered as having neurocardiogenic syncope. In addition, the faster than normal (> 100) mean 24-hour rates) suggested that they also had so-called inappropriate sinus tachycardia. In summary, Group I consisted of patients with a normal, benign, vagal-induced second-degree AV block, whereas the Holter findings in Group II appeared to reflect unusual (but natural, i.e., nonprovoked) electrocardiographic manifestations of certain patients with neurocardiogenic syncope.

N-aralkyl substitution of 2-aminoindans. Synthesis and their inotropic and chronotropic activity in isolated guinea pig atria

Amino substitution of rigid forms of dopamine 4,5-dihydroxy-2-aminoindan and 5,6-dihydroxy-2-aminoindan with aralkyl functionalities were carried out to investigate the role of such structural modifications upon cardiac inotropic-chronotropic activity. Compounds synthesized demonstrated a modest inotropic selectivity, while one of them, described as 5,6-dihydroxy-N-[2-(4-hydroxyphenyl)-1-methylethyl]-2-aminoindan hydrobromide 17, showed a marked inotropic action on isolated heart tissue.

Is preoperative fasting necessary?

The effects of fasting and of histamine (H2) antagonists on gastric volume and acidity were studied in 56 baboons undergoing various surgical procedures under general anesthesia and randomly allocated into 4 groups; group A--fasted for 14 hours; group B--given 100-120 ml of water 3 hours before surgery; groups C and D--also given 100-120 ml of water 3 hours before surgery; in addition, the former received cimetidine 10 mg/kg IM and the latter ranitidine 1.5 mg/kg IM 30-40 minutes before anesthesia. There were no significant differences between groups A and B with respect to the gastric volume and pH. Both ranitidine and cimetidine significantly (P < 0.02) reduced gastric volume and increased gastric pH. Thus, prolonged withholding of oral fluids does not reduce the gastric volume or increase gastric pH. H2-antagonists are effective in reducing both gastric residual volume and pH.

Prevalence of cervical dysplasia and HPV infection according to sexual behavior

A total of 165 uterine cervix smears from Venezuelan women were examined by cytological techniques to identify malignant and pre-malignant cervical changes, as well as to identify Human Papilloma Virus (HPV) DNA types 6, 11, 16, 18, 31, 33 and 35. Of these smears, 119 were from nonmonogamous women who participated in a cervical carcinoma screening program. In this group, HPV-DNA was detected by hybridization in 42 samples (35%) and cervical intraepithelial neoplasia (CIN) in 13 (11%). Forty-six monogamous aboriginal women were similarly studied and no evidence of abnormal cytology or HPV-DNA of the types studied here was found in any of them. In the non-monogamous group, age at first sexual intercourse and index of parity were not associated with cervical HPV infection and/or CIN. The rates of HPV infection, however, were significantly different between the two populations, confirming that sexual behavior involving multiple partners is associated with HPV infection.