Enantiospecific Response in Cross-Polarization Solid-State Nuclear Magnetic Resonance of Optically Active Metal Organic Frameworks

We report herein on a NMR-based enantiospecific response for a family of optically active metal-organic frameworks. Cross-polarization of the ¹H-¹³C couple was performed, and the intensities of the ¹³C nuclei NMR signals were measured to be different for the two enantiomers. In a direct-pulse experiment, which prevents cross-polarization, the intensity difference of the ¹³C NMR signals of the two nanostructured enantiomers vanished. This result is due to changes of the nuclear spin relaxation times due to the electron spin spatial asymmetry induced by chemical bond polarization involving a chiral center. These experiments put forward on firm ground that the chiral-induced spin selectivity effect, which induces chemical bond polarization in the J-coupling, is the mechanism responsible for the enantiospecific response. The implications of this finding for the theory of this molecular electron spin polarization effect and the development of quantum biosensing and quantum storage devices are discussed.

Environmental benchmarks based on ecotoxicological assessment with planktonic species might not adequately protect benthic assemblages in lotic systems

Freshwater ecosystems face widespread diffuse and point-source contamination. Species Sensitivity Distributions (SSDs) have been used as a tool to determine chemical concentration benchmarks that represent protective levels for most species in the environment. Here we used a SSD approach to assess on the adequacy of standard planktonic organisms to reflect the response of benthic communities, critically supporting the structure and function of lotic ecosystems. For the purpose, SSDs reflecting non-lethal responses of standard planktonic and selected benthic organisms were built based on EC50 values (collected in the literature or estimated following testing herein) regarding three model contaminants: potassium dichromate (PD), 3,5-dichlorophenol (DCP) and lead chloride (LC). The derived HC5 estimates were discriminatory between chemicals and the uncertainty associated with the estimate was remarkably low. The HC5 estimates with corresponding uncertainty were generally within the same order of magnitude for the three chemicals tested, with better discrimination between chemicals regarding their hazardous potential being achieved for benthic organisms: DCP was clearly less hazardous than PD, but LC tends to be as hazardous as PD and DCP (assuming the confidence interval ranges). Moreover, benthic communities were more sensitive to both DCP and PD, in this later case the HC5 being lower by more than one order of magnitude than that found for planktonic communities; for LC, confidence intervals overlapped, preventing a feasible assumption regarding differential sensitivity of the compared communities. Microphytobenthos was highlighted as the most sensitive group to the three tested chemicals in SSDs covering the benthic compartment, while SSDs with planktonic organisms did not consistently show trends in sensitivity ordering. Overall, our results suggest that protective benchmarks retrieved from SSDs built with the responses of standard planktonic organisms (which are the most commonly used for regulation purposes) do not adequately protect benthic communities.

Emerging and Reemerging Aedes-Transmitted Arbovirus Infections in the Region of the Americas: Implications for Health Policy

The increasing geographical spread and disease incidence of arboviral infections are among the greatest public health concerns in the Americas. The region has observed an increasing trend in dengue incidence in the last decades, evolving from low to hyperendemicity. Yellow fever incidence has also intensified in this period, expanding from sylvatic-restricted activity to urban outbreaks. Chikungunya started spreading pandemically in 2005 at an unprecedented pace, reaching the Americas in 2013. The following year, Zika also emerged in the region with an explosive outbreak, carrying devastating congenital abnormalities and neurologic disorders and becoming one of the greatest global health crises in years. The inadequate arbovirus surveillance in the region and the lack of serologic tests to differentiate among viruses poses substantial challenges. The evidence for vector control interventions remains weak. Clinical management remains the mainstay of arboviral disease control. Currently, only yellow fever and dengue vaccines are licensed in the Americas, with several candidate vaccines in clinical trials. The Global Arbovirus Group of Experts provides in this article an overview of progress, challenges, and recommendations on arboviral prevention and control for countries of the Americas.

Vaccination of special populations: Protecting the vulnerable

One of the strategic objectives of the 2011-2020 Global Vaccine Action Plan is for the benefits of immunisation to be equitably extended to all people. This approach encompasses special groups at increased risk of vaccine-preventable diseases, such as preterm infants and pregnant women, as well as those with chronic and immune-compromising medical conditions or at increased risk of disease due to immunosenescence. Despite demonstrations of effectiveness and safety, vaccine uptake in these special groups is frequently lower than expected, even in developed countries with vaccination strategies in place. For example, uptake of the influenza vaccine in pregnancy rarely exceeds 50% in developed countries and, although data are scarce, it appears that only half of preterm infants are up-to-date with routine paediatric vaccinations. Many people with chronic medical conditions or who are immunocompromised due to disease or aging are also under-vaccinated. In the US, coverage among people aged 65years or older was 67% for the influenza vaccine in the 2014-2015 season and 55-60% for tetanus and pneumococcal vaccines in 2013, while the coverage rate for herpes zoster vaccination among those aged 60years or older was only 24%. In most other countries, rates are far lower. Reasons for under-vaccination of special groups include fear of adverse outcomes or illness caused by the vaccine, the inconvenience (and in some settings, cost) of vaccination and lack of awareness of the need for vaccination or national recommendations. There is also evidence that healthcare providers' attitudes towards vaccination are among the most important influences on the decision to vaccinate. It is clear that physicians' adherence to recommendations needs to be improved, particularly where patients receive care from multiple subspecialists and receive little or no care from primary care providers.

Effect of vitamin A and zinc supplementation on gastrointestinal parasitic infections among Mexican children

OBJECTIVE

Gastrointestinal parasites continue to be an important cause of morbidity and stunting among children in developing countries. We evaluated the effect of vitamin A and zinc supplementation on infections by Giardia lamblia, Ascaris lumbricoides, and Entamoeba histolytica.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted among 707 children who were 6 to 15 months of age and from periurban areas of Mexico City, Mexico, between January 2000 and May 2002. Children, who were assigned to receive either vitamin A every 2 months, a daily zinc supplement, a combined vitamin A and zinc supplement, or a placebo, were followed for 1 year. The primary end points were the 12-month rates and durations of infection for the 3 parasites and rates of parasite-associated diarrheal disease as determined in stools collected once a month and after diarrheal episodes.

RESULTS

G. lamblia infections were reduced and A. lumbricoides infections increased among children in the combined vitamin A and zinc group or the zinc alone group, respectively. Durations of Giardia infections were reduced among children in all 3 treatment arms, whereas Ascaris infections were reduced in the vitamin A and zinc group. In contrast, E. histolytica infection durations were longer among zinc-supplemented children. Finally, E. histolytica- and A. lumbricoides-associated diarrheal episodes were reduced among children who received zinc alone or a combined vitamin A and zinc supplement, respectively.

CONCLUSIONS

We found that vitamin A and zinc supplementation was associated with distinct parasite-specific health outcomes. Vitamin A plus zinc reduces G. lamblia incidence, whereas zinc supplementation increases A. lumbricoides incidence but decreases E. histolytica-associated diarrhea.

Supplementation with vitamin A reduces watery diarrhoea and respiratory infections in Mexican children

Previous clinical vitamin A trials have found no consistent effect on diarrhoeal disease and respiratory tract infection. These inconsistent results may be due to the distinct effects vitamin A supplementation has among children stratified by factors related to socio-economic status, nutritional status and season. We evaluated the effect of supplementation on the overall incidence of diarrhoeal disease and respiratory tract infections and on the incidence among children stratified by these factors. A total of 188 children, aged 6-15 months, from periurban, marginalized communities of Mexico City were assigned to receive vitamin A ( < 12 months of age, 20,000 IU retinol; >or= 12 months, 45,000 IU retinol) or a placebo every 2 months, and were followed for up to 15 months. Project personnel visited households twice a week to determine the onset and duration of diarrhoeal disease and respiratory tract infections. Vitamin A supplementation had no significant effect on risk of overall diarrhoeal disease but reduced mild watery diarrhoea (incidence rate ratio (RR) 0.69; 95 % CI 0.50, 0.93) and cough with fever (RR 0.69; 95 % CI 0.48, 0.98). Vitamin A supplementation decreased diarrhoeal disease during the summer (RR 0.74; 95 % CI 0.57, 0.94), among non-stunted children (RR 0.69; 95 % CI 0.52, 0.93) and among children from households with better socio-economic measures. Heterogeneity in the response to vitamin A supplementation may reflect heterogeneity in the aetiology and epidemiology of diarrhoeal disease and respiratory tract infections and the impact that supplementation has on the immune response.

Impact of Vitamin A on Selected Gastrointestinal Pathogen Infections and Associated Diarrheal Episodes among Children in Mexico City, Mexico

BACKGROUND

The overall effect of vitamin A supplementation on diarrheal disease in community trials may result from its effect on specific diarrheal pathogens.

METHODS

We conducted a placebo-controlled, double-blind trial of the prophylactic effect of vitamin A on gastrointestinal pathogen infections and clinical symptoms among 188 children in Mexico City, Mexico, from January 1998 to May 1999. Children 6-15 months of age were randomly assigned to receive either a vitamin A supplement (for children <12 months of age, 20,000 international units [IU] of retinol; for children > or =12 months of age, 45,000 IU of retinol) every 2 months or a placebo and were followed for up to 15 months. Stool samples, collected semimonthly, were screened for enteropathogenic Escherichia coli (EPEC), enterotoxigenic E. coli (ETEC), Shiga toxin-producing E. coli (STEC), enteroinvasive E. coli (EIEC), and Giardia lamblia.

RESULTS

Vitamin A supplementation reduced the prevalence of EPEC infections (rate ratio [RR], 0.52 [95% confidence interval {CI}, 0.23-0.86]) and led to shorter durations of both EPEC and ETEC infections. Supplementation also reduced the prevalence of EPEC-associated diarrhea (RR, 0.41 [95% CI, 0.16-1.00]), EPEC-associated fever (RR, 0.15 [95% CI, 0.02-0.98]), and G. lamblia-associated fever (RR, 0.27 [95% CI, 0.13-0.80]). Finally, children who received vitamin A supplementation had shorter durations of EPEC-associated diarrhea than did children who did not receive supplementation but had longer durations of G. lamblia-associated diarrhea.

CONCLUSIONS

These results suggest that the effect of vitamin A supplementation on clinical outcomes may be pathogen dependent.

Vitamin A supplementation reduces the monocyte chemoattractant protein-1 intestinal immune response of Mexican children

The impact of vitamin A supplementation on childhood diarrhea may be determined by the regulatory effect supplementation has on the mucosal immune response in the gut. Previous studies have not addressed the impact of vitamin A supplementation on the production of monocyte chemoattractant protein 1 (MCP-1), an essential chemokine involved in pathogen-specific mucosal immune response. Fecal MCP-1 concentrations, determined by an enzyme-linked immuno absorption assay, were compared among 127 Mexican children 5-15 mo of age randomized to receive a vitamin A supplement (<12 mo of age, 20,000 IU of retinol; > or =12 mo, 45,000 iu) every 2 mo or a placebo as part of a larger vitamin A supplementation trial. Stools collected during the summer months were screened for MCP-1 and gastrointestinal pathogens. Values of MCP-1 were categorized into 3 levels (nondetectable, <median, > or =median). Multinomial logistic regression models were used to determine whether vitamin A-supplemented children had different categorical values of MCP-1 compared with children in the placebo group. Differences in categorical values were also analyzed stratified by gastrointestinal pathogen infections and by diarrheal symptoms. Overall, children who received the vitamin A supplement had reduced fecal concentrations of MCP-1 compared with children in the placebo group (median pg/mg protein +/- interquartile range: 284.88 +/- 885.35 vs. 403.39 +/- 913.16; odds ratio 0.64, 95% CI 0.42-97, P = 0.03). Vitamin A supplemented children infected with enteropathogenic Escherichia coli (EPEC) had reduced MCP-1 levels (odds ratio = 0.38, 95% CI 0.18-0.80) compared with children in the placebo group. Among children not infected with Ascaris lumbricoides vitamin A supplemented children had reduced MCP-1 levels (OR = 0.62, 95% CI 0.41-0.94). These findings suggest that vitamin A has an anti-inflammatory effect in the gastrointestinal tract by reducing MCP-1 concentrations.

The effect of vitamin A supplementation on the intestinal immune response in Mexican children is modified by pathogen infections and diarrhea

Vitamin A supplementation has consistently reduced infant mortality and the severity of pathogen-induced diarrhea. The mechanism by which vitamin A modulates the mucosal immune response to produce these effects remains poorly defined. To address this issue, stools collected during the summer months from 127 Mexican children 5-15 mo old enrolled in a larger, randomized, double-blind, placebo-controlled, vitamin A supplementation trial were screened for interleukin (IL)-4, IL-6, interferon-gamma (IFN-gamma), and gastrointestinal pathogens. Fecal cytokine values were categorized into 3 levels (undetectable, <median, > or =median). Multinomial regression models were used to determine the probability that vitamin A-supplemented children had higher categorical values of a cytokine than children in the placebo group. Differences in categorical values were also analyzed after stratification by gastrointestinal pathogen infections and diarrheal symptoms. Overall, fecal cytokine categorical levels did not differ between children randomized to the 2 arms. Vitamin A-supplemented children infected with enteropathogenic E. coli (EPEC) had reduced IL-4 and IFN-gamma levels [odds ratio (OR) = 0.3, 95% CI 0.13-0.67 and OR = 0.34, 95% CI 0.14-0.83, respectively] compared with children in the placebo group. Vitamin A-supplemented children had increased IL-4 levels when infected with A. lumbricoides (OR = 12.06, 95% CI 0.95-153.85). In contrast, IL-4 levels increased (OR = 2.14, 95% CI 0.94-4.87) and IFN-gamma levels decreased (OR = 0.51, 95% CI 0.26-0.99) among vitamin A-supplemented children with diarrhea compared with children in the placebo group. These findings suggest that the regulation of the mucosal immune response by vitamin A may depend on the type of enteric pathogen infecting the child and the presence of clinical symptoms.

Evaluation of immunogenicity and side effects of triple viral vaccine (MMR) in adults, given by two routes: subcutaneous and respiratory (aerosol)

Adult volunteers from two neighboring health centers were immunized with measles, mumps, rubella vaccine (MMR, Serum Institute of India Ltd.), either given by traditional injections or by an aerosol delivered to the respiratory tract. Baseline and one month post vaccination samples were taken and simultaneously assayed for all three antigens. Subjects were followed-up for temporally associated events after vaccination. The aerosol route was superior for measles, mumps and rubella when baseline titers were controlled for in multivariate analysis. Frequencies of post-vaccination events did not differ with statistical significance between the groups. Further evaluation of the aerosol route for MMR immunization appears warranted.

Measles in Mexico, 1941–2001: Interruption of Endemic Transmission and Lessons Learned

In Mexico, measles occurred in a cyclical endemic-epidemic pattern until the early 1970s. Beginning in 1973, routine vaccination augmented by mass vaccination campaigns led to a decrease in the incidence of measles until the 1989-1990 regional pandemic, when the measles attack rate rose to 80 cases per 100000, resulting in 5899 deaths. Since the pandemic, measles elimination efforts in Mexico have resulted in increasing coverage to >95% among children aged 1-6 years with 2 doses of either measles or measles-mumps-rubella vaccine since 1996 and in coverage of 97.6% among children aged 6-10 since 1999. Surveillance data suggest that the transmission of indigenous measles virus was interrupted in 1997. After almost 4 years without measles cases, in April 2000, measles virus was reintroduced into Mexico and 30 laboratory-confirmed cases were reported. Detection of relatively few cases in nonprogrammatic age groups affirms the high immunization coverage and the sensitivity of measles surveillance in Mexico. We conclude that the specific strategies adopted for measles elimination have enabled Mexico to eliminate the endemic transmission of measles.

Determination of serum aluminum, platelet aggregation and lipid peroxidation in hemodialyzed patients

Aluminum (Al3+) overload is frequently associated with lipid peroxidation and neurological disorders. Aluminum accumulation is also reported to be related to renal impairment, anemia and other clinical complications in hemodialysis patients. The aim of the present study was to determine the degree of lipid peroxidation, platelet aggregation and serum aluminum in patients receiving regular hemodialytic treatment. The level of plasma lipid peroxidation was evaluated on the basis of thiobarbituric acid reactive substances (TBARS). Mean platelet peroxidation in patients undergoing hemodialysis was significantly higher than in normal controls (2.7 +/- 0.03 vs. 1.8 +/- 0.06 nmol/l, P<0.05). Platelet aggregation and serum aluminum levels were determined by a turbidimetric method and atomic absorption spectrophotometry, respectively. Serum aluminum was significantly higher in patients than in normal controls (44.5 +/- 29 vs. 10.8 +/- 2.5 microg/l, P<0.05). Human blood platelets were stimulated with collagen (2.2 microg/ml), adenosine diphosphate (6 microM) and epinephrine (6 microM) and showed reduced function with the three agonists utilized. No correlation between aluminum levels and platelet aggregation or between aluminum and peroxidation was observed in hemodialyzed patients.

Multiresistant extended-spectrum beta-lactamase-producing Klebsiella pneumoniae causing an outbreak of nosocomial bloodstream infection

This article describes an outbreak of bloodstream infection due to clonal dissemination of multiresistant Klebsiella pneumoniae in a neonatal area, during August 1999, in Mexico City General Hospital. The intestinal tract was the likely reservoir, and intensification of Contact Precaution measures contained the outbreak.

Outbreak of nosocomial sepsis and pneumonia in a newborn intensive care unit by multiresistant extended-spectrum beta-lactamase-producing Klebsiella pneumoniae: high impact on mortality

We describe a case-control study of a small outbreak of nosocomial sepsis and pneumonia with high mortality due to clonal dissemination of a multiresistant Klebsiella pneumoniae in the neonatal intensive care unit of a Mexican institution. Our study helped to change nosocomial infection control policy in this hospital.

Genomic variability of Haemophilus influenzae isolated from Mexican children determined by using enterobacterial repetitive intergenic consensus sequences and PCR

Genomic fingerprints from 92 capsulated and noncapsulated strains of Haemophilus influenzae from Mexican children with different diseases and healthy carriers were generated by PCR using the enterobacterial repetitive intergenic consensus (ERIC) sequences. A cluster analysis by the unweighted pair-group method with arithmetic averages based on the overall similarity as estimated from the characteristics of the genomic fingerprints, was conducted to group the strains. A total of 69 fingerprint patterns were detected in the H. influenzae strains. Isolates from patients with different diseases were represented by a variety of patterns, which clustered into two major groups. Of the 37 strains isolated from cases of meningitis, 24 shared patterns and were clustered into five groups within a similarity level of 1.0. One fragment of 1.25 kb was common to all meningitis strains. H. influenzae strains from healthy carriers presented fingerprint patterns different from those found in strains from sick children. Isolates from healthy individuals were more variable and were distributed differently from those from patients. The results show that ERIC-PCR provides a powerful tool for the determination of the distinctive pathogenicity potentials of H. influenzae strains and encourage its use for molecular epidemiology investigations.

State of immunization in the Americas

Countries in the Americas have led the world in conquering infectious diseases preventable through vaccination. In 1971, the Western hemisphere achieved smallpox eradication. In 1991, the Americas were free of indigenous transmission of wild poliovirus. In 1998, overall regional vaccination coverage was 86% for diphtheria-pertussis-tetanus, 89% for oral poliovirus vaccine 3, 98% for bacille Calmette-Guérin vaccine, and 85% for measles. These figures confirm that most of the children in the Americas are protected against these diseases. The breakthroughs obtained in immunization have stimulated countries to promote new initiatives aimed at the control and eradication of other vaccine-preventable diseases and to introduce new vaccines into routine schedules. In the 21st century, vaccines will remain the most cost-effective means of preventing diseases and avoiding expensive treatment costs.

Klebsiella pneumoniae 35 and 36 kDa porins are common antigens in different serotypes and induce opsonizing antibodies

BACKGROUND

Klebsiella pneumoniae is a major cause of neonatal sepsis and nosocomial infections in Mexico. Antibiotic therapy is the first choice for treatment but the increase in multiple resistance strains has forced scientists to look for alternative treatments, such as immunotherapy. In this work, we propose that porins could be a common antigen among four different capsular serotypes of Klebsiella pneumoniae for the production of immune sera with opsonizing capacity.

METHODS

The 35 and 36 kDa porins from four different serotypes of the bacteria were isolated by the Nikaido method followed by purification in Sephacryl column chromatography. The 36 kDa of serotype K8 was further purified by electroelution. The 35 and 36 kDa porins were used to obtain rabbit polyclonal antibodies (PolyAb) to the four serotypes and the 36 kDa from K8 for the production of monoclonal antibodies (MoAb). Antigenic reactivity of PolyAb and MoAb were analyzed by ELISA and WB and their opsonizing capacity for human PMN was measured by chemiluminescence (CL) using capsulated and non-capsulated bacteria.

RESULTS

Porins from the four strains showe electrophoretic homology and cross reaction by ELISA and WB. CL assays indicated that PolyAb opsonized heterologous strains and that MoAb perform this in the absence of capsule.

CONCLUSIONS

K.pneumoniae 35 and 36 kDa porins are common antigens for the four serotypes studied and induce opsonizing antibodies.

Hepatitis B seroprevalence in Latin America

The seroprevalence of hepatitis B was investigated in over 12,000 subjects in six countries of Latin America: Argentina, Brazil, Chile, the Dominican Republic, Mexico, and Venezuela. Each study population was stratified according to age, gender, and socioeconomic status. Antibodies against hepatitis B core antigen (anti-HBc) were measured in order to determine hepatitis B infection. The highest overall seroprevalence was found in the Dominican Republic (21.4%), followed by Brazil (7.9%), Venezuela (3.2%), Argentina (2.1%), Mexico (1.4%), and Chile (0.6%). In all the countries an increase in seroprevalence was found among persons 16 years old and older, suggesting sexual transmission as the major route of infection. In addition, comparatively high seroprevalence levels were seen at an early age in the Dominican Republic and Brazil, implicating a vertical route of transmission.

Hepatitis A in Latin America: a changing epidemiologic pattern

In a multicenter study, hepatitis A virus (HAV) seroprevalence was surveyed in six countries in Latin America in which in 12,000 subjects were stratified for age. The highest rates of seroprevalence were recorded in the Dominican Republic (89.0%) and Mexico (81.0%), with lower rates in Brazil (64.7%), Chile (58.1%), Venezuela (55.7%), and Argentina (55.0%). The seroprevalence of HAV in children between 1 and 5 years of age was less than 50%, except in the Dominican Republic. In the 5-10-year-old age group, seroprevalence rates have also decreased compared with previous reports. This suggests that the epidemiology is shifting from high to intermediate endemicity, with the population susceptible to HAV infection shifting from children to adolescents and adults. Furthermore, data from Brazil, Argentina, and Mexico show that HAV seroprevalence is significantly lower in people living in medium and high socioeconomic conditions. This study suggests the need for appropriate vaccination programs to be implemented targeting children, adolescents, and adults, particularly in higher socioeconomic groups.

Outer membrane protein profiles of paired nasopharyngeal and middle ear isolates of nontypable Haemophilus influenzae from Mexican children with acute otitis media

We studied nontypable Haemophilus influenzae (NTHi) isolates from simultaneous cultures of nasopharyngeal exudates (NEs) and middle ear fluids (MEFs) obtained by tympanocentesis from 57 children with acute otitis media (AOM). Preparations of outer membrane proteins (OMPs) from 14 pairs of NTHi strains recovered from NEs and MEFs from 10 children with unilateral AOM and four with bilateral AOM were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis. The NTHi subtypes were determined by comparing the OMP profiles of the isolated strains with those of eight reference NTHi subtypes. Of the 14 pairs, 10 (71%) were identical, and one (8%) was different; three strains isolated from NEs (21%) did not correspond to any of the reference subtypes (nonsubtypable). Subtypes 4, 6, 5, 3, and 8 were isolated in the present study, thereby showing that their distribution is similar to that of subtypes isolated from children with AOM in the United States and suggesting that common otogenic strains are widely distributed in North America.

Possible role of calmodulin in excystation of Giardia lamblia

The protozoan Giardia lamblia initiates infection when trophozoites emerge from a cyst in the hosts by the excystation process. Although this process is crucial to the initiation of infection by G. lamblia, little is known about its regulation. To study the possible involvement of calmodulin (CaM) in excystation we tested the effect of several CaM antagonists (TFP, W-7, and W-5) on this cellular function. Except for W-5 the rest of these compounds inhibited excystation. The protein kinase C inhibitor H-7 had no effect on excystation, suggesting that CaM antagonists acted by selectively inhibiting CaM. Furthermore, CaM was redistributed after the induction of excystation and there was an increase in its fluorescence and activity. These results suggest that a CaM-dependent process is involved in G. lamblia excystation.

The Bjornstad syndrome (sensorineural hearing loss and pili torti) disease gene maps to chromosome 2q34-36

We report that the Bjornstad syndrome gene maps to chromosome 2q34-36. The clinical association of sensorineural hearing loss with pili torti (broken, twisted hairs) was described >30 years ago by Bjornstad; subsequently, several small families have been studied. We evaluated a large kindred with Bjornstad syndrome in which eight members inherited pili torti and prelingual sensorineural hearing loss as autosomal recessive traits. A genomewide search using polymorphic loci demonstrated linkage between the disease gene segregating in this kindred and D2S434 (maximum two-point LOD score = 4.98 at theta = 0). Haplotype analysis of recombination events located the disease gene in a 3-cM region between loci D2S1371 and D2S163. We speculate that intermediate filament and intermediate filament-associated proteins are good candidate genes for causing Bjornstad syndrome.

Educational Outcomes of an Otitis Media Workshop for Primary Care Providers in Latin America

Otitis media is a prevalent condition that can be diagnosed and treated by primary care providers skilled in otoscopy. Previous analysis demonstrated that brief, intensive instruction at one site in rural Mexico improved the test scores of health care providers and changed long-term practices (Eavey R, et al. Otolaryngol Head Neck Surg 1993;109:895-8). We wanted to confirm these test score findings at other sites. A didactic course on otitis media with a practical otoscopy workshop was conducted at six Mexican locations and in one Venezuelan city by an interdisciplinary group of physicians. The same coded test was given immediately before and after the course. The Wilcoxon test for significance of intra-subject performance before and after intervention was used as a nonparametric assessment. At all seven sites ( n = 190 subjects), test scores demonstrated statistically significant improvement (range = p < 0.001 to p < 0.0001). We conclude that this educational method consistently improved short-term knowledge of otitis media and that further teaching efforts and a longer term practice-impact study are warranted.

Mortality associated with systemic candidiasis in children

The purpose of this study was to determine factors associated with an increased risk of mortality due to systemic Candida infections in children hospitalized at our tertiary care facility. A total of 71 cases of Candida bloodstream infections were identified over a 2-year period. The attack rate was 47 cases of candidemia per 10,000 discharges and the case fatality rate was 46.5%. Sixty-one cases occurred in infants under 2 years; 27 were newborns (38%). Using logistic regression analysis, we evaluated the independent effects of potential risk factors for death due to candidemia. Three factors were associated with the subsequent risk for death due to systemic candida infection: malnutrition (OR = 4.3; 95% CI 1.2-14.8), prior surgery (OR = 3.8; 95% CI 1.2-13.2), and the number of days between the first positive candida blood culture and the onset of antifungal treatment (OR = 1.12; 95% CI 1.06-1.25). Newborns showed an almost three times greater risk of death due to candidemia as compared to other age groups, but this association was only marginally significant (OR = 2.8; 95% CI 0.9-9.3). There was no difference in the rate of candidemia between the 2 years of the study; however, the observed mortality declined significantly from 65% in year one to 20% in year two (p = 0.02). The major finding of this study was to observe that for every day treatment was delayed the risk of death increased significantly. Thus, this study provides support for empirical antifungal therapy early in the course of suspected systemic candidiasis in order to improve survival among children.

Increased frequency of HLA-DR3 and complotype SCO1 in Mexican mestizo children with amoebic abscess of the liver

The increase of HLA-DR3 and complotype SCO1 previously found in Mexican mestizo adults with E. histolytica amoebic abscess of the liver, was also found in Mexican mestizo children of either sex with the same disease, when compared to the healthy control population (adults and/or children) of the same ethnic and socioeconomic background. This HLA and complotype pattern was not found in Mexican Mestizo patients with amoebic rectocolitis. No linkage disequilibrium was found between these and the other MHC determinants tested in this survey. Thus, HLA-DR3 and SCO1 may constitute primary, independent risk factors, not for any kind of amoebic tissue invasion (i.e. amoebic rectocolitis), but specifically for amoebic liver abscess, irrespective of age or sex. The possibility of linkage disequilibrium with other factors (i.e. the TNF family) within or close to the MHC that were not tested in this study, is discussed. Children with amoebic liver abscess revealed a significant increase in HLA-DR5, and the absence of HLA-DR6 when compared to adults with amoebic liver abscess, suggesting that at least in this ethnic group these class II HLA traits may contribute to some of the peculiarities of pediatric amoebic liver abscess as opposed to the adult version of this disease. HLA-DR3, SCO1, but also HLA-DR5 and HLA-DR6 have all been associated with certain forms of immune-dysfunction, and may thus contribute to some of the clinical and immunological features of this parasitic disease.

Nutrition, infection, and immunocompetence

The nutritional status of an individual has a profound effect on both host susceptibility to specific infectious diseases and on their outcome. Available data suggest that specific and aggregate nutritional deficiencies can alter a host's immune response and increase susceptibility to infection. From a nutritional point of view, the process of nutrient loss and redistribution has the potential for being exploited to the benefit of the infected malnourished host. The proposal to use nutritional support to bolster the host response to infection in severely ill malnourished patients gains support from the fact that this reiterative cycle of malnutrition and infection is the main cause of morbidity and mortality in children in underdeveloped countries.

An education model for otitis media care field-tested in Latin America

The World Health Organization has designated the teaching of otitis media management skills a "priority" status. Effective treatment of ear disease requires that the physician be both informationally educated as well as physically trained to use otoscopy. Little is known about how well this education can be provided in a short time and in a foreign country. To more objectively assess teaching effect, results of an education session for rural Mexican pediatric primary-care providers who were given an intensive otitis media lecture and otoscopy skills workshop in 1990 were evaluated. To test immediate cognitive impact, an anonymous written examination was given both before and after the teaching session. Average test scores after the educational sessions improved 24% (p < 0.001) over baseline scores before the sessions. To evaluate long-term impact on clinical practice, a follow-up telephone survey 2 years later was conducted. The use of an otoscope to diagnose otitis media had increased from 40% to 93% of respondents. We conclude that pediatric primary-care providers in rural Mexico possess a baseline level of knowledge about otitis media that can be significantly enhanced with one educational session. Further, this teaching effort produces an impact on practice pattern that lasts at least 2 years.

[Detection of TEM-beta-lactamase in strains of Haemophilus influenzae resistant to ampicillin using the polymerase chain reaction (PCR)]

With the purpose of determining the type of beta-lactamases that mediate ampicillin resistance to in Haemophilus influenzae strains in the Hospital Infantil de México "Federico Gómez", we determined the minimum inhibitory concentration of 180 strains, isolated from different sources, to ampicillin, amoxicillin-clavulanic acid and ampicillin-sulbactam. All ampicillin resistant strains (29) were beta-lactamase positive as determined by nitrocephin hydrolysis. Using PCR with the primers from pBR322, we detected the presence of the gene for the TEM-beta-lactamase in 100% of the ampicillin resistant strains.

Effects of oral soy phosphatidylcholine on phagocytosis, arachidonate concentrations, and killing by human polymorphonuclear leukocytes

A dietary supplement of linoleic acid (LA) as soy phosphatidylcholine (PC) or as triglyceride on polymorphonuclear leukocyte (PMNL) functions, arachidonate (AA) concentrations, AA release, and leukotriene B4 (LTB4) generation was studied in normal adults. Study 1: Eight subjects were fed PC (27 g) or placebo for 3 d in a blinded crossover experiment with PMNL assays at baseline and 4, 7, and 14 d. Study 2: Subjects were fed equal quantities of LA as PC (18 g, n = 8), safflower (SF, n = 4), or soybean oil (SY, n = 4) with PMNL assays at baseline and 48 h. Study 1: PC increased PMNL phagocytosis and killing of Candida albicans twofold (P less than 0.001) and PMNL phospholipid AA content threefold (P less than 0.001); AA release after Candida albicans stimulation increased 5.3-fold, correlating with PMNL killing (r = 0.932) and phagocytosis (r = 0.872). Study 2: PC, but not SF or SY, produced changes similar to those of study 1. With PMNL exposure to calcium ionophore A23187 or N-formyl-methionyl-leucyl-phenylalanine, PC increased LTB4 generation. Phospholipid LA, in contrast to triglyceride LA, enhanced PMNL phospholipid AA, phagocytosis, and killing.

In vitro and in vivo effects of clindamycin on polymorphonuclear leukocyte function

The effects of clindamycin on polymorphonuclear leukocytes (PMNLs) were evaluated in vitro and in vivo in an experimental model and in immunocompromised patients with and without infection. Chemotaxis, chemiluminescence, and bactericidal capacity were evaluated using PMNLs preincubated with clindamycin in different concentrations. In the three phases of the study, clindamycin at a concentration of 2 mg/L significantly increased PMNL function. In contrast, when higher concentrations were used, PMNL function was not modified and in some cases it was decreased. Our findings suggest that clindamycin, in concentrations of 2 mg/L, positively modifies PMNL function.

Evidence of preferential female prevalence of HTLV-I associated tropical spastic paraparesis in Bahia-Brazil

In order to evaluate the prevalence of HTLV-I infection and its association with tropical spastic paraparesis (TSP) in Bahia, a Northeastern State of Brazil, CSF and sera from TSP patients and CSF and/or sera from some selected groups of individuals were studied. The results seem to indicate a higher prevalence of HTLV-I infection in women than men with TSP and among individuals of HIV risk groups. Some alterations of routine analysis of CSF can suggest HTLV-I infection in TSP patients.

[Recurrent respiratory infection in children: its clinical and laboratory evaluation]

Respiratory infections comprise the main cause of medical consultations, and one of two of the first causes of morbidity and mortality in children under five in developing countries. Epidemiological studies have shown that preschool children contract between four and six respiratory infections in the course of a year without this causing any alarm as a deviation from "normality". Yet, the general practitioner and the pediatrician are frequently faced with the dilemma of deciding whether the child who is "always ill" the use of the recurrent infections is, normal or has predisposing conditions to the infections. Among the predisposing conditions for recurrent respiratory infections in children are several host factors, such as immune defense mechanisms and non-immune mechanisms as well as the infections agent and/or the environment. This article is an overview of the clinical and laboratory evaluation findings of children with recurrent respiratory infections.

Ceftizoxime disposition in neonates and infants during the first six months of life

The single-dose pharmacokinetics of ceftizoxime sodium were studied in 52 neonates and infants between 0.1 and 189 days of age. Subjects received ceftizoxime 25 or 50 mg/kg iv over 15-30 minutes. The drug was administered q8-12h for five days to permit tolerance evaluation on repetitive dosing. No differences were observed in ceftizoxime pharmacokinetic parameter estimates relative to dose. However, marked differences were observed in ceftizoxime pharmacokinetic characteristics relative to infant age; ceftizoxime half-life and mean residence time decreased, whereas body clearance increased with infant age. Ceftizoxime volume of distribution remained relatively constant over infant age. No adverse effects associated with ceftizoxime administration were observed. These data suggest that ceftizoxime 50 mg/kg q12h be used for infants less than or equal to 2 weeks of age (less than or equal to 40 weeks postconceptional age) and that 50 mg/kg q8h be administered for older infants.

[Neonatal meningitis: observations on its etiology, mortality and sequelae]

A retrospective study was carried out on all cases diagnosed with neonatal meningitis at the Hospital Infantil de México Federico Gómez. A rate of 9.6 cases per 1,000 discharged patients was found as well as 6.7% association with sepsis. In 50 of the cases analyzed, an etiologic agent was identified in 23 children; the main bacteria identified were Escherichia coli (24%), Klebsiella pneumoniae (14%), Enterobacter (4%), Proteus mirabilis and Pseudomonas sp (2%), respectively. The mortality rate was 60% and sequelae were seen in 13 of the surviving 20 patients. The unfavorable prognosis of neonates with meningitis forces us to establish an early diagnosis, make every effort to identify the causing agent and try new medications as well as co-adjuvant treatments.

[Guidelines for vaccination against measles in children]

After the introduction of massive immunization campaigns in Mexico, started in 1973, the measles mortality rate has been reduced in children under five years of age from 2.8% in 1989 to a level of 1.6% in 1985. Two epidemics occurred in 1985 and 1989 with 19,460 and 20,076 reported cases respectively. In the first quarter of 1990 a total of 22,906 cases were reported. The age distribution has been: patients greater than 1 year 26.3%; 1-4 years 24.8%; 5-14 years 35.5% and greater than 15 years 18.2%. The vaccination coverage, between 1987 and 1988, ranges from 34% to 75% in outbreaks studies and in the National Health Survey. The vaccine efficacy in those outbreaks has been estimated from 63% to 89%. The epidemics have been primary related to low vaccination coverage during the last 15 years. The conglomeration of a cumulative number of non vaccinated persons could explain the distribution of cases in all age groups. The strategy based on two doses as has been recommended in the US, is useful in programs addressed to eradicate measles, but the low resources and limited access to health services in rural communities of Mexico have made these control measures in feasible. The measles control in Mexico, must be based in vaccinate each child at the first anniversary, this strategy could be enough to take off the measles epidemics.

[Complications in children with measles]

Ongoing immunization campaigns have significantly reduced the incidence of measles. To evaluate the efficacy of vaccination policies, however, it is necessary to analyze disease indicators of mortality and of morbidity such as medical complications and sequelae. We reviewed the hospital experience at Hospital Infantil de Mexico regarding children with measles who necessitated hospitalization between January 1976 and December 1989. During this 14 year period, 176 patients with measles were hospitalized; the majority of the cases corresponded to the period between 1985 and 1989. Fifty five percent of the cases corresponded to children under one year of age. Of those older than 12 months, 81% lacked an immunization history. Eighty percent were from Mexico city or from the neighboring state of Mexico. The mayor complications included: respiratory tract infections such as pneumonia (50.8%), diarrhea (18.2%), and less frequent: laringotracheitis, otitis media, myocarditis and pyodermitis. More than 70% were significantly (grade II or III) malnourished. Twenty three patients died, for a mortality of 13%. The factors more likely related to measles mortality were; age less than two years, undernutrition, and more than two medical complications associated. This report emphasizes that medical complications and mortality are more likely to occur in very young unimmunized, malnourished children.

[Nosocomial measles: a proposal for its control in hospitals]

The transmission of measles in medical settings has become increasingly recognized. Due to the lack of information on nosocomial measles in Mexico we performed a 14 year retrospective study at the Hospital Infantil de México Federico Gómez. The objectives of our study were: a) to determine the frequency of the disease in our hospital; b) to determine the association between nutritional status and risk of acquiring nosocomial measles and c) to establish the relationship between nutritional status and complications in morbidity and mortality due to nosocomial measles. Eighty nine children with nosocomial measles were identified. We observed that patients with severe malnutrition had a greater risk of acquiring nosocomial measles developing complication and dying. The most frequent complication was pneumonia.

[Educational and research program on diagnosis and treatment of otitis media in Latin America]

Otitis media in Latin America is an important cause of hearing impairment and infectious complications which can be prevented without an inordinate effort or investment of resources. The Latin American Otitis Media Research and Training Program is a multidisciplinary, international project designed to improve the detection an treatment of otitis media in Latin America. Over 200 health care providers have already participated in pilot seminars presented in Brazil, Costa Rica, and Mexico. These sessions were highlighted by audiovisual presentations emphasizing pneumatic otoscopy. We conclude that this focused program of medical education can significantly contribute to improve primary health care in the region.

[Capacity of opsonic recognition of polymorphonuclear neutrophils in malnourished children]

The opsonic recognition capacity of polymorphonuclear neutrophils (PMNs) was evaluated in 19 noninfected children (13 eutrophic and 6 malnourished) and 22 infected children (10 eutrophic and 12 malnourished) by determining the rosette-formation capacity of the PMNs with sheep erythrocytes. After evaluating the percentage of rosette-forming neutrophils (RFN), we did not observe significant differences between the PMNs from eutrophic children and those from noninfected malnourished children (70.2 +/- 5% vs 67 +/- 3% respectively, P greater than 0.5). In contrast, the opsonic recognition capacity of PMNs from children with acute bacterial infections was significantly lower in the eutrophic (54.4 +/- 5.8%, P less than 0.05) and even more accentuated in the malnourished children (42.8 +/- 5%, P less than 0.01) when compared to the noninfected children. These results indicate that the opsonic recognition capacity of the PMNs decreases during bacterial infections. Due to the critical role of the PMNs as a mechanism of defense against infection, the greater decrease of the opsonic recognition capacity of the PMNs observed in infected malnourished children could be yet another explanation for the greater morbidity and mortality from the infectious processes observed in malnourished children.

In vitro and in vivo effects of subinhibitory concentrations of clindamycin on experimental Klebsiella pneumoniae sepsis

We studied the effect of subinhibitory doses of clindamycin on the course of experimental Klebsiella pneumoniae sepsis. Wistar rats were injected intraperitoneally with an inoculum containing 5 x 10(6) colony-forming units of K. pneumoniae resistant to clindamycin (minimum inhibitory concentration greater than 128 micrograms/ml) and then distributed to receive clindamycin 10 mg/kg/day or placebo for 10 days. All animals were bacteremic at 3 h. When the magnitude of bacteremia was compared, no difference was seen during the first 24 h; however, by 72 h the clindamycin-treated group had a significant decrease in the number of colony-forming units per milliliter blood (p less than 0.01). The mortality rate showed a tendency to decrease in the treated group (0%) as compared with the control group (30%). By 120 h, 3 of the 9 (33%) surviving animals from the control group were still bacteremic versus 0 of 11 (0%) in the clindamycin-treated group. These results suggest that subinhibitory clindamycin therapy can improve bacterial clearance and survival during the course of experimental K. pneumoniae sepsis.

[Impact of infections on mortality in children with cancer]

A study of the role infections play in the death of 29 children with cancer was conducted from 1983 to 1988. An infection was the main cause of death in twelve patients and was associated with hemorrhage in nine. Five of the patients were free of infection at the time of their death. The most frequently found etiological agents found in hemocultures taken while still alive were: Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus viridans, Salmonella enteritidis, Escherichia coli, Enterobacter sp and Candida spp. A retrospective study on the role of infections in the death of children with cancer was conducted. The clinical and autopsy records of 29 children who died between 1983 and 1988 were reviewed. Infection was the main cause of death in twelve patients and was associated with hemorrhage in nine. Five of the patients were free of infection at the time of death. The most frequent etiologic agents found in blood cultures taken while still alive were: Staphylococcus epidermidis.