Single-cell analysis of prenatal and postnatal human cortical development

We analyzed >700,000 single-nucleus RNA sequencing profiles from 106 donors during prenatal and postnatal developmental stages and identified lineage-specific programs that underlie the development of specific subtypes of excitatory cortical neurons, interneurons, glial cell types, and brain vasculature. By leveraging single-nucleus chromatin accessibility data, we delineated enhancer gene regulatory networks and transcription factors that control commitment of specific cortical lineages. By intersecting our results with genetic risk factors for human brain diseases, we identified the cortical cell types and lineages most vulnerable to genetic insults of different brain disorders, especially autism. We find that lineage-specific gene expression programs up-regulated in female cells are especially enriched for the genetic risk factors of autism. Our study captures the molecular progression of cortical lineages across human development.

A CRISPR-engineered isogenic model of the 22q11.2 A-B syndromic deletion

22q11.2 deletion syndrome, associated with congenital and neuropsychiatric anomalies, is the most common copy number variant (CNV)-associated syndrome. Patient-derived, induced pluripotent stem cell (iPS) models have provided insight into this condition. However, patient-derived iPS cells may harbor underlying genetic heterogeneity that can confound analysis. Furthermore, almost all available models reflect the commonly-found ~ 3 Mb "A-D" deletion at this locus. The ~ 1.5 Mb "A-B" deletion, a variant of the 22q11.2 deletion which may lead to different syndromic features, and is much more frequently inherited than the A-D deletion, remains under-studied due to lack of relevant models. Here we leveraged a CRISPR-based strategy to engineer isogenic iPS models of the 22q11.2 "A-B" deletion. Differentiation to excitatory neurons with subsequent characterization by transcriptomics and cell surface proteomics identified deletion-associated alterations in proliferation and adhesion. To illustrate in vivo applications of this model, we further implanted neuronal progenitor cells into the cortex of neonatal mice and found potential alterations in neuronal maturation. The isogenic models generated here will provide a unique resource to study this less-common variant of the 22q11.2 microdeletion syndrome.

Simplified risk-prediction for benchmarking and quality improvement in emergency general surgery. Prospective, multicenter, observational cohort study

BACKGROUND AND AIMS

Emergency General Surgery (EGS) conditions account for millions of deaths worldwide, yet it is practiced without benchmarking-based quality improvement programs. The aim of this observational, prospective, multicenter, nationwide study was to determine the best benchmark cutoff points in EGS, as a reference to guide improvement measures.

METHODS

Over a 6-month period, 38 centers (5% of all public hospitals) attending EGS patients on a 24-h, 7-days a week basis, enrolled consecutive patients requiring an emergent/urgent surgical procedure. Patients were stratified into cohorts of low (i.e., expected morbidity risk <33%), middle and high risk using the novel m-LUCENTUM calculator.

RESULTS

A total of 7258 patients were included; age (mean ± SD) was 51.1 ± 21.5 years, 43.2% were female. Benchmark cutoffs in the low-risk cohort (5639 patients, 77.7% of total) were: use of laparoscopy ≥40.9%, length of hospital stays ≤3 days, any complication within 30 days ≤ 17.7%, and 30-day mortality ≤1.1%. The variables with the greatest impact were septicemia on length of hospital stay (21 days; adjusted beta coefficient 16.8; 95% CI: 15.3 to 18.3; P < .001), and respiratory failure on mortality (risk-adjusted population attributable fraction 44.6%, 95% CI 29.6 to 59.6, P < .001). Use of laparoscopy (odds ratio 0.764, 95% CI 0.678 to 0.861; P < .001), and intraoperative blood loss (101-500 mL: odds ratio 2.699, 95% CI 2.152 to 3.380; P < .001; and 500-1000 mL: odds ratio 2.875, 95% CI 1.403 to 5.858; P = .013) were associated with increased morbidity.

CONCLUSIONS

This study offers, for the first time, clinically-based benchmark values in EGS and identifies measures for improvement.

[Epidemiology and risk factors of patients with intra-abdominal postsurgical infection treated with tigecycline: a cohort study]

OBJECTIVE

To study a cohort of patients with intra-abdominal postsurgical infection treated with tigecycline to analyze its effectiveness and mortality related factors.

METHODS

Prospective study of patients with intra-abdominal postsurgical infection with microbiological isolation and treated with tigecycline.

RESULTS

Out of 103 patients only 61 full fit inclusion criteria. Mean age was 67 year-old and 72% were male. Charlson score was ≥ 3 in 65.5%, being diabetes and colon cancer the most prevalent diseases. Cancer surgery was the most frequent procedure (n=44, 72%) and previous antibiotic administration was present in 43 cases (69%). Pitt score was ≥ 3 in 69% and most prevalent bacteria were Escherichia coli (38 %), Enterococcus spp. (34%; mainly Enterococcus faecium) and Klebsiella pneumoniae together with Enterobacter cloacae (28%). Tigecycline was prescribed alone (17; 28%) or in combination with other antibiotics (44; 72%), mainly meropenem (25; 57%) or amikacin (19, 43%). 11 patients died (18%), all of which suffered extended cancer surgery and isolation of extended-spectrum betalactamase producing Enterobacteriaceae. Factors statistically associated to death in univariate analysis were Charlson score >3, pH <7.3 and leucocyte count >20.000 cells/mm3.

CONCLUSIONS

As being a cohort of patients treated with tigecycline, E. faecium isolation was very frequent. Non-fatal evolution was achieved in 82% cases, being tigecycline a potentially good option in the empiric treatment of very severe infections.

Encephalitis and AMPA receptor antibodies: Novel findings in a case series of 22 patients

OBJECTIVE

We report the clinical features, comorbidities, and outcome of 22 newly identified patients with antibodies to the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR).

METHODS

This was a retrospective review of patients diagnosed between May 2009 and March 2014. Immunologic techniques have been reported previously.

RESULTS

Patients' median age was 62 years (range 23-81; 14 female). Four syndromes were identified: 12 (55%) patients presented with distinctive limbic encephalitis (LE), 8 (36%) with limbic dysfunction along with multifocal/diffuse encephalopathy, one with LE preceded by motor deficits, and one with psychosis with bipolar features. Fourteen patients (64%) had a tumor demonstrated pathologically (5 lung, 4 thymoma, 2 breast, 2 ovarian teratoma) or radiologically (1 lung). Additional antibodies occurred in 7 patients (3 onconeuronal, 1 tumor-related, 2 cell surface, and 1 tumor-related and cell surface), all with neurologic symptoms or tumor reflecting the concurrent autoimmunity. Treatment and outcome were available from 21 patients (median follow-up 72 weeks, range 5-266): 5 had good response to immunotherapy and tumor therapy, 10 partial response, and 6 did not improve. Eventually 5 patients died; all had a tumor or additional paraneoplastic symptoms related to onconeuronal antibodies. Coexistence of onconeuronal antibodies predicted a poor outcome (p = 0.009).

CONCLUSION

Anti-AMPAR encephalitis usually manifests as LE, can present with other symptoms or psychosis, and is paraneoplastic in 64% of cases. Complete and impressive neurologic improvement can occur, but most patients have partial recovery. Screening for a tumor and onconeuronal antibodies is important because their detection influences outcome.

Persistent abdominal symptoms in US adults after short-term stay in Mexico

BACKGROUND

Postinfectious irritable bowel syndrome (PI-IBS) has been reported as a complication of bacterial diarrhea including travelers' diarrhea (TD). This study assessed the role of TD among US students in Mexico in triggering the onset of persistent abdominal symptoms (PAS) and IBS.

METHODS

We conducted a 6-month follow-up of a cohort of 817 US students in Mexico as short-term study to assess the frequency of PAS and IBS. Using Rome II criteria for IBS, groups of students with PAS were then categorized as PI-IBS if they met the symptom criteria for IBS or as suffering from functional abdominal disorder (FAD) if they did not meet the criteria.

RESULTS

FAD and IBS were commonly found in US students 6 months after leaving Mexico. Important variables in their development were younger adult age, longer stays in Mexico and occurrence of acute diarrhea while in Mexico. Diarrhea while in Mexico occurred more commonly for those later diagnosed with FAD, 101/196 (52%), relative risk (RR) = 1.5 [confidence interval (CI) 1.2-1.8; p = 0.001]; IBS, 20/32 (63%), RR = 2.5 (CI 1.2-5.0; p = 0.007); and PAS (FAD + IBS), 121/228 (53%), RR = 1.5 (CI 1.2-1.8; p < 0.001) compared with subjects who had experienced diarrhea while in Mexico but were not diagnosed with PAS at 6 months, 227/589 (39%). Diarrhea caused by heat-labile enterotoxin-producing enterotoxigenic Escherichia coli or Providencia ssp. demonstrated a greater risk of developing PAS.

CONCLUSIONS

PAS occurred commonly in a subset of younger adult travelers who stayed longer in Mexico and experienced acute diarrhea while there. Further studies with this cohort will focus on host genetic associations with the development of PAS.

Pre- and posttransplant monitoring of alloantibodies by complement-dependent cytotoxicity and luminex methodologies in liver transplantation

BACKGROUND

This study evaluated the influence of circulating anti-HLA antibodies on outcomes of 97 liver allografts from deceased donors.

METHODS

Human leukocyte antigen (HLA) antibody screening was performed by both complement-dependent cytotoxicity (CDC) and multiparameter Luminex microsphere-based assays (Luminex assay).

RESULTS

The agreements between T- and B- cell CDC and Luminex assays were 67% and 77% for pre- and posttransplant specimens, respectively. Graft dysfunction was not associated with either positive pretransplant CDC or Luminex panel-reactive antibody (PRA) values. Likewise, positive posttransplant T- or B- cell CDC PRA values were not associated with graft dysfunction. In contrast, posttransplant Luminex PRA values were significantly higher among patients with graft dysfunction compared with subjects with good outcomes (P = .017).

CONCLUSION

Posttransplant monitoring of HLA antibodies with Luminex methodology allowed identification of patients at high-risk for poor graft outcomes.

Neurological manifestation of colonic adenocarcinoma

Paraneoplastic neurologic disorders are extremely rare in cancer patients and are most commonly associated with certain tumors, such as ovarian cancer, small cell lung cancer, and breast cancer. We report here a paraneoplastic neurological syndrome in a 53-year-old man with colonic adenocarcinoma with a solitary liver metastasis. His paraneoplastic syndrome was successfully treated by methylprednisolone and primary oncologic therapies including neoadjuvant chemotherapy and definitive surgery. This is also the first documented case of simultaneous manifestation of a sensory neuropathy and limbic encephalitis with colon cancer.

A randomized, double-blind, pilot study of rifaximin 550 mg versus placebo in the prevention of travelers' diarrhea in Mexico during the dry season

BACKGROUND

Rifaximin has been shown to be effective in treating and preventing travelers' diarrhea (TD) during the summer season.

METHODS

The goal of this double-blinded multicenter trial was to assess the efficacy and safety of rifaximin 550 mg administered once daily for 14 days compared with placebo in the prevention of TD during the dry season in Mexico.

RESULTS

There were 101 participants randomized. Overall, 25 participants developed TD during the 3 weeks of the study: 22% from the rifaximin group and 29% from the placebo group (p = 0.4). Mild diarrhea (defined as only one or two unformed stools during a 24-h period plus at least one abdominal symptoms) developed in only 3 (6%) participants taking rifaximin compared with 10 (21%) taking placebo during the first week of study (p = 0.03). No clinically significant or serious adverse events were reported.

CONCLUSIONS

Antibiotic prophylaxis of TD in Mexico during the dry season needs to be further studied and its benefits weighed against the benefits of self-treatment.

Campylobacter jejuni is not an important pathogen as a cause of diarrhea in US travelers to Mexico

Campylobacter jejuni is an unusual cause of travelers' diarrhea acquired in Mexico, but previous studies have relied only on stool culture for diagnosis. We conducted a cohort study to determine if antibody seroconversion to C jejuni would better reflect the occurrence of infection acquired in Mexico. Serum IgG, IgA, and IgM antibodies to Campylobacter seroconverted in only 2 of 353 participants (0.6%). These data further support that C jejuni infection is an unusual cause of travelers' diarrhea in US visitors to Mexico.

Impact of education, income and chronic disease risk factors on mortality of adults: does 'a pauper-rich paradox' exist in Latin American societies?

OBJECTIVES

To test the hypothesis that an inverse association exists between socio-economic position and all-cause mortality in a developing country in Latin America.

STUDY DESIGN

Prospective cohort study carried out in Chile using data from a simple random sample of 920 apparently healthy subjects (weighted population 11,600 aged 30-89 years) followed for 8 years.

METHODS

Education level (0-8 years, 9-12 years and > or = 13 years) and income quartiles were established at the outset of the study, along with behavioural and biological risk factors for chronic diseases: smoking, alcohol use, obesity, diabetes, hypertension, lipids and family history of death by cardiovascular disease. Relative risks of all-cause mortality were estimated using age-adjusted Cox regression models.

RESULTS

During the follow-up period, 46 deaths were observed. Adjusting for age, gender, and behavioural and biological risk factors, the mortality risk for increasing categories of education after controlling for income was 1.0, 0.76 and 0.33 (P for trend<0.01). In contrast, the relative risk for increasing levels of income after controlling for education was 1.0, 0.98, 1.33 and 1.17 (P for trend=0.07).

CONCLUSION

While education level had a protective effect on mortality risk of Chilean adults, income had a slightly unfavourable effect on survival. This finding is described as suggestive of a 'pauper-rich paradox', since the higher income quantiles in this study correspond with the lower income levels in most developed countries. Nevertheless, due to the small number of deaths, additional research is required to assess the validity of these findings.

Impact of parity on anthropometric measures of obesity controlling by multiple confounders: a cross-sectional study in Chilean women

AIM

To find out whether there is an association between parity and obesity, evaluated through body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) in Chilean women after controlling for sociodemographic characteristics, health risk and gynaeco-obstetric factors.

DESIGN

Cross-sectional study, using baseline data of the San Francisco Project.

SETTING

San Francisco de Mostazal, located in the central region of Chile, 6512 Chilean-Hispanic women (Spanish heritage with a variable indigenous component).

METHODS

A weighted random sample of 508 women who had their first pregnancy inside the primary child-bearing ages. Data were collected between 1997 and 1999. Statistical associations between parity and different anthropometric measurements of adiposity in multiple linear (MLnR) and logistic regression models (MLtR) were evaluated.

RESULTS

In MLnR a modest parity-related increment in BMI and practically null increment in WC, WHR and WHtR was observed. Covariates that showed a statistically significant association with anthropometric measures of adiposity were age, low education, marital status, employment, smoking, smoking cessation, hypertension, diabetes, dyslipidaemia, parent's obesity, menarche and fetal macrosomia. Crude odds ratio (OR) showed a strong association between parity and anthropometric markers of obesity. Nevertheless, after adjustments in MLtR models, the association remained only for BMI. All the measures of abdominal obesity related to parous women showed OR smaller than 1 (95% confidence intervals 0.57 to 0.96).

CONCLUSIONS

Parity modestly influences BMI, but does not seem to be related to WC, WHR and WHtR after controlling by confounders. Parity can increase adiposity but not necessarily following an abdominal pattern.

Enterotoxigenic Escherichia coli heat-labile toxin seroconversion in US travelers to Mexico

BACKGROUND AND AIMS

Enterotoxigenic Escherichia coli (ETEC) is the most common bacterial pathogen isolated from travelers suffering of diarrhea. Exposure to heat-labile toxin (LT) produces a high rate of seroconversion. However, the role of LT-producing ETEC (LT-ETEC) as a cause of diarrhea is controversial. We conducted a cohort study in US students traveling to Mexico to assess the ETEC-LT seroconversion rate after natural exposure.

METHODS

Participants provided a serum sample on arrival and departure and a stool sample when ill. ETEC-LT immunoglobulin G antibodies were measured by enzyme-linked immunosorbent assay, and LT-ETEC were detected by means of polymerase chain reaction done on fecal DNA.

RESULTS

A total of 422 participants with a mean age of 34.5 years were followed a mean of 19.9 days; 304 were females (72.0%), and 319 (75.6%) traveled during the summer months. In total, 177 individuals (41.9%) developed travelers' diarrhea and 33.9% had LT-ETEC identified in their stools. Among individuals having an LT-ETEC strain, 74% seroconverted compared to 11% of those not having diarrhea (p < 0.0001). When analyzed with a logistic regression model, the odds of seroconversion were significantly reduced in participants not having LT-ETEC in their stool (odds ratio = 0.1, p < 0.0001) after adjusting for season, length of stay, age, gender, race, and ethnicity.

CONCLUSION

In US young adults traveling to Mexico, ETEC-LT seroconversion reliably identifies individuals naturally exposed to ETEC and correlates with symptomatic illness, length and season of travel.

Hilar mossy cells share developmental influences with dentate granule neurons

Mossy cells are the major class of excitatory neurons in the dentate hilus. Although mossy cells are involved in a range of physiological and pathological conditions, very little is known about their ontogeny. To gain insight into this issue, we first determined the developmental stage at which mossy cells can be reliably identified with the molecular markers calretinin and GluR2/3 and found that hilar mossy cells were first identifiable around the end of the 1st postnatal week. Birthdating studies combined with staining for these markers revealed that the appearance of mossy cells coincided with the first wave of dentate granule cell production during mid-gestation. Since mossy cells are born as the first granule cells are produced and it is believed that mossy cells originate from the neuroepithelium adjacent to the dentate progenitor zone, we examined to what extent the development of mossy cells is controlled by the same molecular pathways as that of granule cells. To do this, we analyzed the production of mossy cells in Lef1 and NeuroD mutant animals, in which granule cell production is disrupted during precursor proliferation or neuronal differentiation, respectively. The production of mossy cells was almost entirely lost in both mutants. Collectively, these data suggests that hilar mossy cells, unlike CA subfield pyramidal cells, are influenced by many of the same developmental cues as dentate granule cells.

Diversidad genética de 12 LOCI microsatelitales utilizados en pruebas de paternidad equina en Chile

Se investigó la diversidad genética de 12 loci microsatelitales (HMS2, HMS3, HMS6, HMS7, HTG4, HTG6, AHT4, AHT5, VHL20, ASB2, HTG7 y HTG10) utilizados en pruebas de filiación equina en Chile en una muestra poblacional de 45 caballos Criollos chilenos por medio del contenido de información polimórfica, heterocigosis y exceso o déficit de heterocigotos. Además, se estimó la probabilidad de exclusión de paternidad por locus y general considerando los 12 loci. Los resultados indican que la variabilidad genética de los microsatélites analizados es significativamente elevada en la población estudiada. Todos los loci analizados resultaron polimórficos. El número de alelos por locus, varió entre 4 y 10. La heterocigosis esperada promedio (He), considerando todos los loci, fue de 0,76, con un rango que osciló entre 0,52 y 0,88. El promedio de la heterocigosis observada (Ho) sobre el conjunto de todos los marcadores fue de 0,65. La probabilidad de exclusión de paternidad por locus osciló entre 14 a 59%. Al considerar los 12 loci en conjunto, la exclusión de paternidad se puede atribuir con 99,7% de certeza.

Expression of SDF-1 and CXCR4 during reorganization of the postnatal dentate gyrus

Previous studies have demonstrated that stromal cell-derived factor 1 (SDF-1) is crucial for early dentate development; however, the mouse mutants for this chemokine and its only receptor, CXCR4, are neonatally lethal, making conclusions about the role of these molecules in postnatal development difficult to sustain. Previous expression analyses have used single labeling, but the distribution of CXCR4 is complex and to determine the cell types expressing CXCR4 requires multiple marker labeling. In this study, we examined the distribution of SDF-1 and CXCR4 mRNAs during the first postnatal weeks, combining these markers with several other cell-type-specific markers. We found that SDF-1 has three sites of expression: (1) continuation of prenatal expression in the meninges; (2) expression in Cajal-Retzius cells occupying the molecular layer of the upper and lower blades of the dentate, and (3) the maturing dentate granule neurons themselves. The timing of expression in these three sites corresponds to alterations in the distribution of the primary cell types expressing CXCR4 during the same periods, notably the expression of CXCR4 in radial-glial-like GFAP-expressing dentate precursors and immature dentate granule neurons. Taken together, our data suggest potential ongoing roles for SDF-1/CXCR4 signaling in the dentate gyrus during the early postnatal period that will be tested in the future with more precise genetic approaches.

High genetic diversity in Chilean populations of wheat yellow rust (Puccinia striiformis f. sp. tritici West.) assessed by RAPD and AFLP

Wheat yellow rust (Puccinia striiformis f. sp. tritici West. PST) is one of the main fungal diseases that causes major yield losses in the central and southern wheat production area of Chile. Chilean plant breeding programs have been using specific resistance genes to control this disease and resistance was frequently lost due to the appearance of new pathotypes of this pathogen. This resulted in a frequent change of wheat cultivars in the country. The objective of this work was to determine the genetic polymorphism among PST samples collected in wheat fields throughout the country, using randomly amplified polymorphic DNA (RAPD), and amplified fragment length polymorphism (AFLP). Twenty-nine PST populations from 5 locations were analysed with 64 RAPD primers and 6 combinations of AFLP primers. The coefficients of similarity (53% for RAPD and 14% for AFLP) indicated that the populations of yellow rust in Chile are highly diverse, in contrast with similar studies performed in other countries. This observation is supported by the virulence spectrum of PST population. This stressed the need to pyramid 2 or more major genes in commercial cultivars. Alternatively, the deployment of adult plant resistance gene combinations should be conducted. AFLP technique was more robust for analysis of the genetic diversity of PST compared with RAPD, because of its reproducibility and high level of polymorphism. The analysis of genetic similarity data among yellow rust populations grouped most of the PST population according to their geographic origin.

Analysis of body fluid mixtures by mtDNA sequencing: An inter-laboratory study of the GEP-ISFG working group

The mitochondrial DNA (mtDNA) working group of the GEP-ISFG (Spanish and Portuguese Group of the International Society for Forensic Genetics) carried out an inter-laboratory exercise consisting of the analysis of mtDNA sequencing patterns in mixed stains (saliva/semen and blood/semen). Mixtures were prepared with saliva or blood from a female donor and three different semen dilutions (pure, 1:10 and 1:20) in order to simulate forensic casework. All labs extracted the DNA by preferential lysis and amplified and sequenced the first mtDNA hypervariable region (HVS-I). Autosomal and Y-STR markers were also analysed in order to compare nuclear and mitochondrial results from the same DNA extracts. A mixed stain prepared using semen from a vasectomized individual was also analysed. The results were reasonably consistent among labs for the first fractions but not for the second ones, for which some laboratories reported contamination problems. In the first fractions, both the female and male haplotypes were generally detected in those samples prepared with undiluted semen. In contrast, most of the mixtures prepared with diluted semen only yielded the female haplotype, suggesting that the mtDNA copy number per cell is smaller in semen than in saliva or blood. Although the detection level of the male component decreased in accordance with the degree of semen dilution, it was found that the loss of signal was not consistently uniform throughout each electropherogram. Moreover, differences between mixtures prepared from different donors and different body fluids were also observed. We conclude that the particular characteristics of each mixed stain can deeply influence the interpretation of the mtDNA evidence in forensic mixtures (leading in some cases to false exclusions). In this sense, the implementation of preliminary tests with the aim of identifying the fluids involved in the mixture is an essential tool. In addition, in order to prevent incorrect conclusions in the interpretation of electropherograms we strongly recommend: (i) the use of additional sequencing primers to confirm the sequencing results and (ii) interpreting the results to the light of the phylogenetic perspective.

Embryonic and early postnatal abnormalities contributing to the development of hippocampal malformations in a rodent model of dysplasia

While there are many recent examples of single gene deletions that lead to defects in cortical development, most human cases of cortical disorganization can be attributed to a combination of environmental and genetic factors. Elucidating the cellular or developmental basis of teratogenic exposures in experimental animals is an important approach to understanding how environmental insults at particular developmental junctures can lead to complex brain malformations. Rats with prenatal exposure to methylazoxymethanol (MAM) reproduce many anatomical features seen in epilepsy patients. Previous studies have shown that heterotopic clusters of neocortically derived neurons exhibit hyperexcitable firing activity and may be a source of heightened seizure susceptibility; however, the events that lead to the formation of these abnormal cell clusters is unclear. Here we used a panel of molecular markers and birthdating studies to show that in MAM-exposed rats the abnormal cell clusters (heterotopia) first appear postnatally in the hippocampus (P1-2) and that their appearance is preceded by a distinct sequence of perturbations in neocortical development: 1) disruption of the radial glial scaffolding with premature astroglial differentiation, and 2) thickening of the marginal zone with redistribution of Cajal-Retzius neurons to deeper layers. These initial events are followed by disruption of the cortical plate and appearance of subventricular zone nodules. Finally, we observed the erosion of neocortical subventricular zone nodules into the hippocampus around parturition followed by migration of nodules to hippocampus. We conclude that prenatal MAM exposure disrupts critical developmental processes and prenatal neocortical structures, ultimately resulting in neocortical disorganization and hippocampal malformations.

Brain armadillo protein delta-catenin interacts with Abl tyrosine kinase and modulates cellular morphogenesis in response to growth factors

delta-Catenin associates with adhesive junctions and facilitates cellular morphogenesis (Lu et al., 1999). Here we show that delta-catenin colocalizes with actin filaments and Abl tyrosine kinase in the growth cones of cultured hippocampal neurons. PC12 cells induced to express delta-catenin show accelerated neurite extension upon nerve growth factor (NGF) stimulation. STI571, an Abl family kinase inhibitor, further accentuates these stimulatory effects. delta-Catenin is a potent substrate for Abl in vitro using an immunocomplex assay and most of the Abl-induced tyrosine phosphorylation within cells is present in the N-terminus of delta-catenin. When delta-catenin-expressing epithelial cells are induced to scatter in response to hepatocyte growth factor (HGF), STI571 leads to the rapid redistribution of delta-catenin and changes in cellular morphology. We suggest that delta-catenin is a possible Abl substrate and acts downstream of Abl to orchestrate actin-based cellular morphogenesis.

Environmental contaminants in prey and tissues of the peregrine falcon in the Big Bend Region, Texas, USA

Peregrine falcons (Falco peregrinus) have been recorded nesting in Big Bend National Park, Texas, USA and other areas of the Chihuahuan Desert since the early 1900s. From 1993 to 1996, peregrine falcon productivity rates were very low and coincided with periods of low rainfall. However, low productivity also was suspected to be caused by environmental contaminants. To evaluate potential impacts of contaminants on peregrine falcon populations, likely avian and bat prey species were collected during 1994 and 1997 breeding seasons in selected regions of western Texas, primarily in Big Bend National Park. Tissues of three peregrine falcons found injured or dead and feathers of one live fledgling also were analyzed. Overall, mean concentrations of DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene], a metabolite of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane], were low in all prey species except for northern rough-winged swallows (Stelgidopteryx serripennis, mean = 5.1 microg/g ww). Concentrations of mercury and selenium were elevated in some species, up to 2.5 microg/g dw, and 15 microg/g dw, respectively, which upon consumption could seriously affect reproduction of top predators. DDE levels near 5 microg/g ww were detected in carcass of one peregrine falcon found dead but the cause of death was unknown. Mercury, selenium, and DDE to some extent, may be contributing to low reproductive rates of peregrine falcons in the Big Bend region.

Maternal variables related to sexually abused children's functioning

OBJECTIVE

The purpose of this study was to explore how mothers' developmental history and current functioning affects their sexually abused children's functioning and recovery.

METHOD

A sample of 67 African-American mothers and their sexually abused children participated in this study. Interviews and a range of adult and child measures were administered in order to assess maternal developmental history and current functioning, and child functioning.

RESULTS

Mothers' past experiences as children were associated with their children's behavior and general functioning following the sexual abuse. Mothers who experienced more discontinuity of childhood care, who were sexually abused as children, and/or had more problems in their family of origin had children who showed poorer functioning and more behavioral symptomatology. In addition, mothers who currently were experiencing more trauma symptomatology, reported substance abuse, and/or were less able to provide support to their children, had children with more behavior problems and poorer functioning.

CONCLUSIONS

The findings from this study point to the impact of mothers' developmental history and current functioning upon the symptomatology of their sexually abused children.

[Reproduction of the bird Mimus gilvus (Passeriformes: Mimidae) in Maracaibo, Venezuela]

Four pairs of the poorly understood tropical mockingbird Mimus gilvus were captured and color banded at a grassland in Maracaibo, Venezuela in June 1997. Throughout the following 8 months, individuals were observed two days per week for 4 hours each. We recorded courtship behaviour, nest construction, incubation, parental care, territory defense and timing of reproductive cycle. Pairs lived in defined territories defended primarily by the male. Both sexes participated in nest building which began at the start of two rainy seasons: April and October. Between April and June, 80% of nests were parasited by the shiny cowbird (Molothrus bonariensis). No parasitism was recorded in the later nesting season. Consequently, breeding success for the April and October seasons was 20% and 83% respectively. Only the female incubated and the mean clutch size was 2.2 eggs.

Reliability and validity of a chronic care facility adaptation of the Clinical Dementia Rating scale

OBJECTIVE

This study investigated the reliability and validity of a chronic care facility adaptation of the Clinical Dementia Rating scale (CDR-CC).

METHOD

Sixty-two residents in a chronic care facility participated in an inter-rater and 1 month test-retest reliability study. The instrument was validated against the Mini-Mental State Examination (MMSE).

RESULTS

Inter-rater and 1 month test-retest reliability for the global CDR-CC score were excellent (intraclass correlation coefficients 0.99 and 0.92, respectively). The CDR-CC domain and global scores were negatively correlated with the MMSE.

CONCLUSIONS

The CDR-CC is a global assessment tool that reliably and validly measures cognitive and functional impairment in a chronic care setting.

[Streptococcus pneumoniae: evolution of antibiotic resistance in a pediatric hospital in Córdoba, Argentina]

The wide variety of prevalence of antimicrobial resistant Streptococcus pneumoniae in different countries confirms the importance of determining local patterns of resistance. From 1992 to 2000, we studied the pattern of antimicrobial resistance in S. pneumoniae and its evolution along the years, using 468 strains isolated in the Hospital de Niños de Córdoba. A total of 177 isolates (37.8%) were not susceptible to penicillin, with 19% intermediate and 18.8% resistant strains. High and intermediate resistance levels to cefotaxime were 4.9% and 10.9%, respectively. Decreased susceptibility to trimethoprim/sulfamethoxazole (TMS), erythromycin, chloramphenicol, and rifampin was found in 194 isolates (41.5%), 32 (6.8%), 13 (2.8%) and 3 (0.6%), respectively. No isolates resistant to vancomycin were detected. The most commonly combined resistance patterns were: penicillin/TMS (35.6%) and penicillin/TMS/cefotaxime (11.8%). This study highlights the increased rate of drug resistant S. pneumoniae during the last years, and the importance of antimicrobial resistance surveillance of adequate empirical therapy involving local and regional susceptibility patterns.

Mitochondrial DNA sequences for 118 individuals from northeastern Spain

A population database was generated from 118 unrelated Caucasoid individuals living in Spain. Sequence polymorphisms of the mitochondrial DNA (mtDNA) control region, hypervariable regions I and II (HVRI and HVRII) were determined using the polymerase chain reaction (PCR) and direct sequencing. A total of 102 different sequences were found as defined by 105 variable positions. The most common sequence occurred six times, and this sequence is also the most frequent in other European populations such as Austria, Germany and Britain. The mean pair-wise difference for the two HVR regions taken together was 7.74. The study revealed that transitions made up the majority of the variations (88%), whereas we observed a significantly lower frequency of transversions (8%). Also one individual in this study was observed with two positions of heteroplasmy at nucleotides 150 (C/T) and 153 (G/A). A statistical estimate of the results for this population showed a genetic diversity of 0.99. The probability of two random individuals showing identical mtDNA haplotypes is 1.3%. In order to use the mtDNA analysis in forensic casework, we consider that it is of crucial importance to know the frequency of the different sequences of mtDNA, and this data base study could be a useful tool to statistically evaluate the results.

Evidence of a sex-dependent association between the MSX1 locus and nonsyndromic cleft lip with or without cleft palate in the Chilean population

Prior studies have implicated an involvement of the Msx1 homeobox gene in cleft palate in mice and its homolog in humans (called MSX1 in the HOX7 gene, located on chromosome 4). In this study we present evidence of a sex-dependent association between MSX1 and non-syndromic cleft lip/palate (NSCLP) in the Chilean population. The sample included 73 NSCLP cases, 37 from multiplex families (Mx), 36 from simplex families (Sx), and 87 controls. Polymerase chain reaction amplification of the MSX1 intragenic microsatellite (CA)n-sequence shows significant (p = 0.035) differences in the allele frequencies between NSCLP-Mx males and control males. These differences are mainly due to frequency differences in allele *2 (173 base pairs) among cases (21.9%) and controls (13.2%). When the NSCLP cases are subdivided by sex and positive family history (Mx versus Sx), the Mx males (27.8%) as well as the total NSCLP-Mx cases (25.7%) showed significantly higher frequencies of allele *2, compared to controls (11.4% and 13.2%, respectively). Analysis of the genotype data indicates that the relative risk for NSCLP is greater for persons carrying allele *2 (i.e., odds ratio [OR] larger than 1), reaching significance for all Mx cases (OR = 2.67; 95% confidence interval [CI], 1.10 to 6.52) and even more pronounced for Mx males (OR = 3.33; 95% CI, 1.08 to 10.32). Taken together, these findings support the hypothesis that the genetic variation at the MSX1 locus is a predisposing gene involved in sex-dependent susceptibility to clefting and that it also differentiates simplex from multiplex families.

[Antimicrobial resistance of Shigella spp. in Córdoba, Argentina, during the period 1990-1997]

This study analyzed the evolution of antimicrobial resistance in 771 isolates of Shigella spp. obtained from a total of 9,195 feces cultures done between 1990 and 1997 in a children's hospital in Córdoba, Argentina. S. flexneri, which was responsible for 73% of the Shigella infections, was the species with the greatest resistance. The frequency of S. flexneri resistance to the three antibiotics most used (ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol) increased from 10% in 1990 to 58% in 1997 (P < 0.001). Considering each of the drugs individually, the resistance to ampicillin increased from 60% to 100% (P < 0.001), the resistance to chloramphenicol from 13% to 71% (P < 0.001), and the resistance to trimethoprim-sulfamethoxazole from 79% to 84% (P = 0.22). For S. sonnei, the increase in resistance to ampicillin (from 36% in 1990 to 54% in 1997) was not statistically significant (P = 0.20), nor was the reduction in resistance to trimethoprim-sulfamethoxazole, which went from 82% in 1990 to 55% in 1997 (P = 0.08). Only two S. sonnei isolates were found that were resistant to chloramphenicol, one in 1995 and another in 1997; two S. sonnei isolates were found with resistance to all three antibiotics. We consider it essential to carry out susceptibility tests of each Shigella clinical isolate, to detect changes in the resistance profile and thus modify empiric treatment.

[Association between nonsyndromic cleft lip/palate and microsatellite markers located in 4q]

BACKGROUND

Nonsyndromic cleft lip with or without cleft palate (NSCLP) is a common craniofacial defect. Association studies have suggested that a clefting locus is located on chromosome 4q at or near two microsatellite markers D4S175 and D4S192.

AIM

To test the hypothesis on the possible presence of a clefting locus on chromosome 4q.

MATERIAL AND METHODS

We carried out an association study on a sample of unrelated NSCLP patients, of their unaffected relatives and in controls. Both probands and relatives were further analyzed depending if they originated from simplex or multiplex families. DNA was analyzed with two PCR markers close to the putative NSCLP locus, dinucleotide repeats D4S175 and D4S192. PCR products were resolved by PAGE and visualized by silver staining. Statistical analysis was performed by means of chi 2 log ratio.

RESULTS

Significant differences between NSCLP and controls were observed when comparing the allele frequency distribution of D4S192 both in the total sample as well as in NSCLP-multiplex and simplex cases. No significant differences for D4S175 were observed in any of the comparisons. Unaffected relatives showed significant differences with controls both for D4S175 and D4S192.

CONCLUSIONS

Our results support the hypothesis that a NSCLP locus maps on chromosome 4q close to the microsatellite marker D4S192. No differences were observed between NSCLP multiplex and simplex cases versus controls, implying that they do not represent different etiologic entities. The results of the present and previous studies in the same group of patients support the hypothesis that several major interacting genes participate in the etiology of NSCLP.

[Association of non-syndromic cleft lip and cleft palate with microsatellite markers located in 6p]

BACKGROUND

Nonsyndromic cleft lip with or without cleft palate (NSCLP) is a common craniofacial developmental defect. Association studies have suggested that a clefting locus is located on chromosome 6p at or near two possible loci, Factor 13A (FI3A) in the region 6p 25-24 and HLA at 6p 21.3.

AIM

To test the hypothesis on the possible presence of a major gene on chromosome 6p associated with NSCLP.

PATIENTS AND METHODS

We carried out an association study on a sample of unrelated NSCLP patients from multiplex (Mx) and simplex (Sx) families, of their unaffected relatives and in control individuals. DNA was analyzed with three PCR markers close to the putative NSCLP locus, dinucleotide repeats at loci D6S89, D6S109 and D6S105. PCR products were resolved by PAGE and visualized by silver staining. Statistical analysis was performed by means of chi 2 log ratio.

RESULTS

Significant differences were observed when comparing the allele frequency distribution of D6S89 in patients with NSCLP and controls and in patients with NSCLP-Mx and controls. No significant differences were observed for patients with NSCLP-Sx. D6S109 and D6S105 showed no significant differences in any of the comparisons.

CONCLUSIONS

Our results support the hypothesis that a NSCLP locus maps on 6p23 very close to D6S89. Results for D6S109 and D6S105 do not show a clear association. Differences observed between NSCLP-MX and Sx families seem to represent different etiologic entities. The results of the present study, plus those already published for candidate loci, TGFA and MSX1, support the hypothesis that several interacting major genes participate in the etiology of NSCLP.

delta-catenin, an adhesive junction-associated protein which promotes cell scattering

The classical adherens junction that holds epithelial cells together consists of a protein complex in which members of the cadherin family linked to various catenins are the principal components. delta-catenin is a mammalian brain protein in the Armadillo repeat superfamily with sequence similarity to the adherens junction protein p120(ctn). We found that delta-catenin can be immunoprecipitated as a complex with other components of the adherens junction, including cadherin and beta-catenin, from transfected cells and brain. The interaction with cadherin involves direct contact within the highly conserved juxtamembrane region of the COOH terminus, where p120(ctn) also binds. In developing mouse brain, staining with delta-catenin antibodies is prominent towards the apical boundary of the neuroepithelial cells in the ventricular zone. When transfected into Madin-Darby canine kidney (MDCK) epithelial cells delta-catenin colocalized with cadherin, p120(ctn), and beta-catenin. The Arm domain alone was sufficient for achieving localization and coimmunoprecipitation with cadherin. The ectopic expression of delta-catenin in MDCK cells altered their morphology, induced the elaboration of lamellipodia, interfered with monolayer formation, and increased scattering in response to hepatocyte growth factor treatment. We propose that delta-catenin can regulate adhesion molecules to implement the organization of large cellular arrays necessary for tissue morphogenesis.

A prospective, randomized, double-blind trial evaluating the efficacy of ursodeoxycholic acid in prevention of liver transplant rejection

Acute cellular rejection (ACR) after orthotopic liver transplantation occurs in 50% to 80% of patients despite the recent advances in immunosuppressive therapy. Adjuvant use of ursodeoxycholic acid (UDCA) is theoretically attractive, but studies have shown conflicting results. In this randomized, controlled study, we evaluated the efficacy of UDCA in reduction of the incidence of ACR. Thirty patients were randomized to receive either UDCA (15 mg/kg) or placebo in addition to the standard triple-drug regimen; 14 patients received UDCA, and the rest received placebo, for 3 to 6 months. The diagnosis of ACR was based on histologic criteria. Three patients withdrew from the study within 1 month of therapy, all because of capsule size. There was no difference in the total incidence of ACR between the placebo and UDCA groups, with 12 and 11 episodes within 6 months, respectively; the overall incidence of rejection was 77%. There were also no differences in the incidence of recurrent rejection, in the number of rejection episodes occurring after 5 days of therapy, or in the use of OKT3. There was no difference in 1-year survival between groups. This study shows that adjuvant therapy with UDCA in addition to standard triple-drug immunosuppressive therapy does not reduce the incidence of ACR.

Basal extracellular signal-regulated kinase activity modulates cell-cell and cell-matrix interactions

Suppression of the basal extracellular signal-regulated kinase (ERK) activity in PC12 cells markedly altered their phenotype. Wild-type cells grew in a dissociated pattern adherent to the substrate. The stable expression of an ERK inhibitory mutant resulted in the formation of calcium-dependent aggregates which were less adherent to the substrate. Concomitantly, the cells reorganized their actin cytoskeleton and increased their expression of several adherens junction proteins, particularly cadherin. Metabolic labeling demonstrated an increased synthesis of cadherin and beta-catenin in these cells. Nontransfected PC12 cells and a ras-transformed MDCK cell line also formed aggregates and increased their expression of adherens junction proteins following treatment with the selective MEK inhibitor PD98059. A peptide containing the HAV cadherin recognition sequence attenuated the aggregation. These studies suggest that in PC12 and epithelial cells, ERKs are pivotally positioned to enhance substrate interactions when active or to release homotypic interactions when suppressed.

Differential clinical and epidemiological features in children with Campylobacter diarrhoea, mixed-agent diarrhoea and Campylobacter diarrhoea plus parenteral infections

A prospective study of 111 young Peruvian children with Campylobacter jejuni diarrhoea showed that it behaves as an endemic enterotoxigenic-like, waterborne, milkborne, and zoonotic disease. Although there were no definite differential features between pure C. jejuni diarrhoea, mixed-agent diarrhoea, and C. jejuni diarrhoea plus parenteral infections, children with C. jejuni diarrhoea plus parenteral infections were all inpatients, were more frequently malnourished and more frequently exhibited systemic symptoms. Campylobacter jejuni associated with other enteric pathogens did not seem to act synergistically as the disease was not particularly severe in this group.

[Trichinosis outbreak in Purranque County, X Region, Chile. October-November, 1992]

An outbreak of trichinosis occurred in Purranque County, X Region, Chile, between october and november of 1992, which involved 36 persons. The incubation period, determined by the clinical picture and laboratory assays, fluctuated between 10 and 12 days. Myalgias (88.9%) and palpebral oedema (86.1%), were the most important symptoms, followed by fever (44.4%) and headache (33.3%). Eosinophils count ranged from two to 42% the first week, and this value raised to 55% the second week of the outbreak. Anti-Trichinella spiralis antibodies were determined by some serological tests such as: precipitin test (PT), bentonite flocculation test (BFT) and indirect hemagglutination test (IHAT) in sera from 28 patients at the beginning of the outbreak. PT was positive in 46.4% of the cases, followed by IHAT (21.4%) and BFT (3.6%). After 15 days, the three tests were performed in sera from 12 patients. At that time, the positivity was elevated in all of them: PT (100.0%), BFT (66.7%) and IHAT (91.7%). It is believed that the outbreak had its origin in infected pork meat that was consumed raw or insufficiently cooked without a previous veterinary inspection.

Occult blood and fecal leukocytes as screening tests in childhood infectious diarrhea: an old problem revisited

During a 24-month period 446 children with diarrhea and 16 controls had examination of their stools for leukocytes and for occult blood. Fecal leukocytes were found in 36, 16 and 18% of children with Salmonella-Shigella-Campylobacter, rotavirus or enterotoxigenic Escherichia coli, or cryptosporidial diarrhea, respectively. Similarly 43, 39 and 38% of these groups, respectively, as well as 13% of controls had occult blood. Notably 70% of 10 Shigella cases had fecal leukocytes. In 166 children with mixed pathogens leukocytes were seen in 27 and 8% of children with Salmonella-Shigella-Campylobacter or noninvasive pathogen, respectively. Likewise 44 and 18% of these groups had occult blood. Agreement between both tests being positive was poor, the highest result being 50% for Shigella. Dysentery combined with both tests positive was associated with 15 (88%) cases of invasive agents present in stool cultures, and combination of dysentery with fecal leukocytes was associated with 21 (72%) cases of invasive agents recovered. The results of these tests should be interpreted in the context of the clinical situation. A combined clinical-epidemiologic and screening tests-based approach to infectious diarrhea of childhood is suggested.

Forensic determination of pregnancy hormones in human bloodstains

When different bloodstains are encountered at the scene of crime, it is possible to discriminate those from a pregnant woman from others. Human chorionic gonadotrophin, human placental lactogen, total oestriol and progesterone in the stains may be determined with radioimmunoassay techniques using commercial kits. Only 1 cm2 of bloodstain is needed for the determination of all four parameters, which gives information about the state of pregnancy. More than 100 stains of blood from women in all stages of pregnancy, normal menstruating women, menopausal and post-menopausal women and male subjects, and of menstrual blood were analysed. Bloodstains from pregnant women were easy to evaluate with the four determinations, only very early pregnancies being undetected. Stains from non-pregnant women were negative or below the cut-off level. Two case examples are also described.

Effect of Somatostatin on TSH levels in non-toxic sporadic goiter

Somatostatin (SS-14; growth hormone-release inhibiting hormone) was infused into eight patients with non-toxic sporadic goiter and into eleven normal control subjects. Each patient was given 150 microgram(s) of somatostatin as an intravenous bolus and 350 microgram(s) by infusion over a period of 60 minutes. Somatostatin did not lower the basal TSH levels as compared to the pre-infusion levels in this type of goiter, but produced a decrease in the TSH response to TRH during and after the infusion.