Optimized quantification of intra-host viral diversity in SARS-CoV-2 and influenza virus sequence data

High error rates of viral RNA-dependent RNA polymerases lead to diverse intra-host viral populations during infection. Errors made during replication that are not strongly deleterious to the virus can lead to the generation of minority variants. However, accurate detection of minority variants in viral sequence data is complicated by errors introduced during sample preparation and data analysis. We used synthetic RNA controls and simulated data to test seven variant-calling tools across a range of allele frequencies and simulated coverages. We show that choice of variant caller and use of replicate sequencing have the most significant impact on single-nucleotide variant (SNV) discovery and demonstrate how both allele frequency and coverage thresholds impact both false discovery and false-negative rates. When replicates are not available, using a combination of multiple callers with more stringent cutoffs is recommended. We use these parameters to find minority variants in sequencing data from SARS-CoV-2 clinical specimens and provide guidance for studies of intra-host viral diversity using either single replicate data or data from technical replicates. Our study provides a framework for rigorous assessment of technical factors that impact SNV identification in viral samples and establishes heuristics that will inform and improve future studies of intra-host variation, viral diversity, and viral evolution. IMPORTANCE When viruses replicate inside a host cell, the virus replication machinery makes mistakes. Over time, these mistakes create mutations that result in a diverse population of viruses inside the host. Mutations that are neither lethal to the virus nor strongly beneficial can lead to minority variants that are minor members of the virus population. However, preparing samples for sequencing can also introduce errors that resemble minority variants, resulting in the inclusion of false-positive data if not filtered correctly. In this study, we aimed to determine the best methods for identification and quantification of these minority variants by testing the performance of seven commonly used variant-calling tools. We used simulated and synthetic data to test their performance against a true set of variants and then used these studies to inform variant identification in data from SARS-CoV-2 clinical specimens. Together, analyses of our data provide extensive guidance for future studies of viral diversity and evolution.

Childhood-Onset Lupus Nephritis in the Childhood Arthritis and Rheumatology Research Alliance Registry: Short-Term Kidney Status and Variation in Care

OBJECTIVE

The goal was to characterize short-term kidney status and describe variation in early care utilization in a multicenter cohort of patients with childhood-onset systemic lupus erythematosus (cSLE) and nephritis.

METHODS

We analyzed previously collected prospective data from North American patients with cSLE with kidney biopsy-proven nephritis enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry from March 2017 through December 2019. We determined the proportion of patients with abnormal kidney status at the most recent registry visit and applied generalized linear mixed models to identify associated factors. We also calculated frequency of medication use, both during induction and ever recorded.

RESULTS

We identified 222 patients with kidney biopsy-proven nephritis, with 64% class III/IV nephritis on initial biopsy. At the most recent registry visit at median (interquartile range) of 17 (8-29) months from initial kidney biopsy, 58 of 106 patients (55%) with available data had abnormal kidney status. This finding was associated with male sex (odds ratio [OR] 3.88, 95% confidence interval [95% CI] 1.21-12.46) and age at cSLE diagnosis (OR 1.23, 95% CI 1.01-1.49). Patients with class IV nephritis were more likely than class III to receive cyclophosphamide and rituximab during induction. There was substantial variation in mycophenolate, cyclophosphamide, and rituximab ever use patterns across rheumatology centers.

CONCLUSION

In this cohort with predominately class III/IV nephritis, male sex and older age at cSLE diagnosis were associated with abnormal short-term kidney status. We also observed substantial variation in contemporary medication use for pediatric lupus nephritis between pediatric rheumatology centers. Additional studies are needed to better understand the impact of this variation on long-term kidney outcomes.

Intraarticular steroids as DMARD-sparing agents for juvenile idiopathic arthritis flares: Analysis of the Childhood Arthritis and Rheumatology Research Alliance Registry

BACKGROUND

Children with juvenile idiopathic arthritis (JIA) who achieve a drug free remission often experience a flare of their disease requiring either intraarticular steroids (IAS) or systemic treatment with disease modifying anti-rheumatic drugs (DMARDs). IAS offer an opportunity to recapture disease control and avoid exposure to side effects from systemic immunosuppression. We examined a cohort of patients treated with IAS after drug free remission and report the probability of restarting systemic treatment within 12 months.

METHODS

We analyzed a cohort of patients from the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry who received IAS for a flare after a period of drug free remission. Historical factors and clinical characteristics and of the patients including data obtained at the time of treatment were analyzed.

RESULTS

We identified 46 patients who met the inclusion criteria. Of those with follow up data available 49% had restarted systemic treatment 6 months after IAS injection and 70% had restarted systemic treatment at 12 months. The proportion of patients with prior use of a biologic DMARD was the only factor that differed between patients who restarted systemic treatment those who did not, both at 6 months (79% vs 35%, p < 0.01) and 12 months (81% vs 33%, p < 0.05).

CONCLUSION

While IAS are an option for all patients who flare after drug free remission, it may not prevent the need to restart systemic treatment. Prior use of a biologic DMARD may predict lack of success for IAS. Those who previously received methotrexate only, on the other hand, are excellent candidates for IAS.

Optimized Quantification of Intrahost Viral Diversity in SARS-CoV-2 and Influenza Virus Sequence Data

High error rates of viral RNA-dependent RNA polymerases lead to diverse intra-host viral populations during infection. Errors made during replication that are not strongly deleterious to the virus can lead to the generation of minority variants. However, accurate detection of minority variants in viral sequence data is complicated by errors introduced during sample preparation and data analysis. We used synthetic RNA controls and simulated data to test seven variant calling tools across a range of allele frequencies and simulated coverages. We show that choice of variant caller, and use of replicate sequencing have the most significant impact on single nucleotide variant (SNV) discovery and demonstrate how both allele frequency and coverage thresholds impact both false discovery and false negative rates. We use these parameters to find minority variants in sequencing data from SARS-CoV-2 clinical specimens and provide guidance for studies of intrahost viral diversity using either single replicate data or data from technical replicates. Our study provides a framework for rigorous assessment of technical factors that impact SNV identification in viral samples and establishes heuristics that will inform and improve future studies of intrahost variation, viral diversity, and viral evolution.

IMPORTANCE

When viruses replicate inside a host, the virus replication machinery makes mistakes. Over time, these mistakes create mutations that result in a diverse population of viruses inside the host. Mutations that are neither lethal to the virus, nor strongly beneficial, can lead to minority variants that are minor members of the virus population. However, preparing samples for sequencing can also introduce errors that resemble minority variants, resulting in inclusion of false positive data if not filtered correctly. In this study, we aimed to determine the best methods for identification and quantification of these minority variants by testing the performance of seven commonly used variant calling tools. We used simulated and synthetic data to test their performance against a true set of variants, and then used these studies to inform variant identification in data from clinical SARS-CoV-2 clinical specimens. Together, analyses of our data provide extensive guidance for future studies of viral diversity and evolution.

Social determinants of health influence disease activity and functional disability in Polyarticular Juvenile Idiopathic Arthritis

BACKGROUND

Social determinants of health (SDH) greatly influence outcomes during the first year of treatment in rheumatoid arthritis, a disease similar to polyarticular juvenile idiopathic arthritis (pJIA). We investigated the correlation of community poverty level and other SDH with the persistence of moderate to severe disease activity and functional disability over the first year of treatment in pJIA patients enrolled in the Childhood Arthritis and Rheumatology Research Alliance Registry.

METHODS

In this cohort study, unadjusted and adjusted generalized linear mixed effects models analyzed the effect of community poverty and other SDH on disease activity, using the clinical Juvenile Arthritis Disease Activity Score-10, and disability, using the Child Health Assessment Questionnaire, measured at baseline, 6, and 12 months.

RESULTS

One thousand six hundred eighty-four patients were identified. High community poverty (≥20% living below the federal poverty level) was associated with increased odds of functional disability (OR 1.82, 95% CI 1.28-2.60) but was not statistically significant after adjustment (aOR 1.23, 95% CI 0.81-1.86) and was not associated with increased disease activity. Non-white race/ethnicity was associated with higher disease activity (aOR 2.48, 95% CI: 1.41-4.36). Lower self-reported household income was associated with higher disease activity and persistent functional disability. Public insurance (aOR 1.56, 95% CI 1.06-2.29) and low family education (aOR 1.89, 95% CI 1.14-3.12) was associated with persistent functional disability.

CONCLUSION

High community poverty level was associated with persistent functional disability in unadjusted analysis but not with persistent moderate to high disease activity. Race/ethnicity and other SDH were associated with persistent disease activity and functional disability.

Cryptosporidium parvum in diarrheic calves detected by microscopy and identified by immunochromatographic and molecular methods

Cryptosporidium is an important protozoan parasite that causes diarrhea in neonates and young bovines. The objective of the present study was to determine the frequency of Cryptosporidium infection in animals of dairy farms of the Metropolitan Region (Santiago), Chile. Fecal samples of 205 newborn calves with diarrhea were studied and used for comparing the efficiency of two microscopic staining methods for diagnosis of the parasite, the auramine (AU) and a modified Ziehl-Neelsen (ZN) procedure. Out of the 205 fecal samples, we detected oocysts in 115 (56.1%) with AU and 102 (49.8%) with ZN. Comparison of results obtained with the two microscopic techniques showed significant difference (p<0.05), AU being more sensitive. On the other hand, concordance between the two methods was almost perfect (kappa value of 0.83). The results with these two operator dependent methods were confirmed using an operator independent immunochromatographic (IC) method. The IC method also enabled us to determine the identity of the parasite species as that of Cryptosporidium parvum. Identification of the parasite species was further corroborated by performing a Cryptosporidium species-specific polymerase chain reaction (PCR) test on few samples taken at random. Overall, the results showed a high number of infected animals suggesting the parasite C. parvum as a major parasitic disease agent of neonatal calves with diarrhea in dairy farms of the Metropolitan Region (Santiago) of Chile.

Ectopic pregnancy early diagnosis markers

Ectopic pregnancy (EP) is a high-risk medical condition with an incidence of 1.9% in reported pregnancies, and has proven to be the most common cause of pregnancy-related deaths in the first trimester. The clinical symptoms can mimic non-EP conditions, thus creating a challenge for developing diagnostic criteria and new diagnostic tools. Early diagnosis of ectopic pregnancy is essential in order to minimize the morbidity and to assess the need for urgent surgical intervention. Currently, ultrasound and serum biomarkers are used by clinicians for early detection and diagnosis. This review summarizes and comments on the available literature on the various markers including their utility and their statistical parameters.

Comparison of bronchoscopic bronchoalveolar lavage vs blind lavage with a modified nasogastric tube in the etiologic diagnosis of ventilator-associated pneumonia

OBJECTIVE

Our objective was to compare the results of a blind lavage vs a bronchoscopic-guided bronchoalveolar lavage for the etiologic diagnosis of ventilator-associated pneumonia (VAP).

DESIGN

Prospective study in consecutive patients with high probability of VAP. Every patient underwent both procedures, in a formally randomized fashion. The interpretation of quantitative cultures was done in a blind fashion.

SETTING

Single center study, with a 20 bed medical and surgical Intensive Care Unit of the University Hospital in Monterrey, Mexico.

PATIENTS

Twenty-five patients with high probability of VAP.

INTERVENTIONS

Every patient underwent blind bronchoalveolar lavage with a modified nasogastric tube, and a bronchoscopic-guided bronchoalveolar lavage.

RESULTS

Twenty-one patients underwent both procedures. Four patients were excluded due to contamination of the cultures. The quantitative cultures were compared in a paired fashion. Only two patients had discordant cultures. The correlation coefficient between the number of colonies was very high, r=0.90 (95% confidence interval [CI], 0.77-0.96; p=0.0001).

CONCLUSIONS

The blind bronchoalveolar lavage with a modified nasogastric tube is a valuable tool for the identification of etiologic agent in VAP, particularly when trained bronchoscopists or the necessary resources for bronchoscopic-guided bronchoalveolar lavage are not readily available.

Microsurgical considerations of the anterior spinal and the anterior-ventral spinal arteries

BACKGROUND

There are few data describing the microanatomy of the anterior-ventral spinal (AVSA) and anterior spinal arteries (ASA) and discussing their clinical and surgical implications. We describe the anatomical features of this arterial complex, and highlight their use when planning and performing surgical approaches to lesions involving the ventral aspect of the medulla and the foramen magnum.

METHOD

The microsurgical anatomy and branching pattern of the AVSA and the ASA from fifty human cadaver brain stems is described using a surgical microscope.

RESULTS

We found one anterior-ventral spinal artery at each side in 30 of the brain stems (60%). The ASA was a direct branch emerging from the left vertebral artery (VA) in 15 (30%), from the right VA in 4 (8%), and from the basilar artery (BA) in one brain stem (2%). The previously described as "typical pattern" of the junction of the AVS arteries from both sides, was observed only in 9 brain stems (18%). The anterior communicating spinal artery (ACoSA) was observed in 15 brain stems (30%). Also multiple ACoS arteries were described in one brain stem. Both, the AVSA and the ASA were observed to send long circumferential branches that supplied irrigation to the olive in 42 (84%) brain stems.

CONCLUSIONS

This anatomical study gives important information for a better understanding of the clinical picture of ischemic lesions of the brain stem, such as the medial medullary syndrome, and highlights the remarkable role of the AVSA and ASA as anatomical landmarks during the surgical approaches to lesions involving the ventral aspect of the medulla and the foramen magnum.

Vascular anatomy of the foramen of Vicq d'Azyr: a microsurgical perspective

INTRODUCTION

The foramen of Vicq d'Azyr, is a triangular-shaped area located rostral to the ventral median fissure of the medulla oblongata. Its importance relies on the fact that it is penetrated by small vessels from the vertebrobasilar axis that nourish vital pontine nuclei and tracts. We described the microvascular anatomy of the perforating vessels of the foramen of Vicq d'Azyr (FVA).

MATERIALS AND METHODS

The vertebrobasilar junction arteries and the perforating arteries of the foramen of Vicq d'Azyr were examined using a surgical microscope in 21 formalin-fixed brain stems.

RESULTS

The total number of perforating branches found was 286 in the 21 brains, an average of 13.6 perforators per brain, range 7 to 22. They arose as distal branches of 73 main trunks, average of 3.5 per brain, range 2 to 5, originating mainly from the basilar artery in 41 (56.1 %); the left ventral spinal artery in 12 (16.4 %), and the left vertebral artery in 8 (11 %). The average outer diameters of the left and right vertebral arteries were 3.2 mm and 2.9 mm, 4.1 mm for the basilar artery, and 0.6 mm for the right and left ventral spinal arteries. The branching pattern and interesting anatomic variations of the main vessels of the vertebro-basilar junction are also described.

DISCUSSION

The vascular anatomy of the infratentorial compartment is highly variable. These variations should be kept in mind to avoid pitfalls during vascular or tumor surgery. In contrast, the entering locations of perforating vessels remain constant, referring to these zones as key areas when planning or doing surgical procedures in this region.

Human infection by Pseudoterranova decipiens (Nematoda, Anisakidae) in Chile: report of seven cases

From 1997 to 1999, we identified seven human cases of infection by fourth stage larvae of Pseudoterranova decipiens in Chile. All identified larvae were coughed up by the patients. Subjects were 10-55 years old; five were female. Some patients complained of coughing, expectoration, pharyngeal pain, nausea or anal and nasal pruritus. Larvae of three patients were coughed up from 36 h to 7 days after having eaten raw (cebiche or sushi) or lightly fried fish. P. decipiens has a marine life cycle. Infective third stage larva develop to adult stage in pinniped mammals. The nematode eggs are voided with the host faeces and develop and hatch releasing third stage larvae. Some crustaceans and fish act as hosts of third stage larvae. Man is an accidental host for third or fourth stage larvae.

Early programming of T cell populations responding to bacterial infection

The duration of infection and the quantity of Ag presented in vivo are commonly assumed to influence, if not determine, the magnitude of T cell responses. Although the cessation of in vivo T cell expansion coincides with bacterial clearance in mice infected with Listeria monocytogenes, closer analysis suggests that control of T cell expansion and contraction is more complex. In this report, we show that the magnitude and kinetics of Ag-specific T cell responses are determined during the first day of bacterial infection. Expansion of Ag-specific T lymphocyte populations and generation of T cell memory are independent of the duration and severity of in vivo bacterial infection. Our studies indicate that the Ag-specific T cell response to L. monocytogenes is programmed before the peak of the innate inflammatory response and in vivo bacterial replication.

[Environmental contamination with Toxocara sp. eggs in public squares and parks from Santiago, Chile, 1999]

Most of cases of visceral larva migrans syndrome are caused by Toxocara canis larvae. Man acquires the infection by accidental ingestion of ripe eggs of the helminth. In order to find out the frequency of the presence of Toxocara sp. eggs in dog fecal specimens from public places of Santiago city in 1999 july-september a study was carried out in 84 squares and 12 parks from 32 counties. Three fecal samples were collected in each of these places, making a total of 288. Each sample was processed according to a modified Telemann method and three smears of each were microscopically examined. Toxocara sp. eggs were found in 39 (13.5%) fecal specimens. In 28/84 (33.3%) squares and in 8/12 (66.7%) parks these eggs were detected. These results make necessary the control of dogs and cats populations with the aim of reduce the presence of animals without responsible owners. It should be advisable to prevent dogs and cats defecation in public areas grounds, trying to exclude these animals from recreation areas.

MHC class I restricted T cell responses to Listeria monocytogenes, an intracellular bacterial pathogen

Studies of the murine immune response to infection with the intracellular bacterial pathogen Listeria monocytogenes have provided a wealth of information about innate and acquired immune defenses in the setting of an infectious disease. Our studies have focused on the MHC class I restricted, CD8+ T cell responses of Balb/c mice to L. monocytogenes infection. Four peptides that derive from proteins that L. monocytogenes secretes into the cytosol of infected cells are presented to cytotoxic T lymphocyte (CTL) by the H2-Kd major histocompatibility complex (MHC) class I molecule. We have found that bacterially secreted proteins are rapidly degraded in the host cell cytosol by proteasomes that utilize, at least in part, the N-end rule to determine the rate of degradation. The MHC class I antigen processing pathway is remarkably efficient at generating peptides that bind to MHC class I molecules. The magnitude of in vivo T cell responses, however, is influenced to only a small degree by the amount of antigen or the efficiency of antigen presentation. Measurements of in vivo T cell expansion following L. monocytogenes infection indicate that differences in the sizes of peptide-specific T cell responses are more likely owing to differences in the repertoire of naive T cells than to differences in peptide presentation. This notion is supported by our additional finding that dominant T cell populations express a more diverse T cell receptor (TCR) repertoire than do subdominant T cell populations.

Regulation of glial Na+/K+-ATPase by serotonin: identification of participating receptors

The purpose of the present study was the characterization of the receptors participating in the regulatory mechanism of glial Na+/K+-ATPase by serotonin (5-HT) in rat brain. The activity of the Na+ pump was measured in four brain regions after incubation with various concentrations of serotoninergic agonists or antagonists. A concentration-dependent increase in enzyme activity was observed with the 5-HT1A agonist R (+)-2-dipropylamino-8-hydroxy-1,2,3, 4-tetrahydronaphthalene hydrobromide (8-OH-DPAT) in homogenates or in glial membrane enriched fractions from cerebral cortex and in hippocampus. Spiperone, a 5-HT1A antagonist, completely inhibited the response to 8-OH-DPAT but had no effect on Na+/K+-ATPase activity in cerebellum where LSD, a 5-HT6 agonist, elicited a dose-dependent response similar to that of 5-HT. In brainstem, a lack of response to 5-HT and other agonists was confirmed. Altogether, these results show that serotonin modulates glial Na+/K+-ATPase activity in the brain, apparently not through only one type of 5-HT receptor. It seems that the receptor system involved is different according to the brain region. In cerebral cortex, the response seems to be mediated by 5-HT1A as well as in hippocampus but not in cerebellum where 5-HT6 appears as the receptor system involved.

[Seasonal variation of intestinal protozoa infections in outpatients of the north section of Santiago, Chile. 1995-1996]

Formalin preserved fecal samples from 6,058 and 5,863 outpatients were examined for intestinal parasites during 1995 and 1996 respectively. Prevalence rates of infections by intestinal protozoa in both years were similar. By age group (0-9, 10-19 and > 20 years old) Blastocystis hominis was observed in 18.6-19.3, 37.0-31.1 and 25.3-25.4% in 1995-1996 respectively. Prevalence of Giardia intestinalis infections decreased from 16.6-17.4% in the 0-9 year-old children group to 4.1-4.5% in patients over 20 years. Overall percentages of infection by Entamoeba histolytica varied between 4.2 and 10.9. Rates of infections by G. intestinalis, E. histolytica, and Entamoeba coli observed during rainy-cold months (april-september) of the year versus drywarmy period (october-march) were the same. On the contrary, more cases of B. hominis infection 25.8% versus 18.2% (this difference being statistically significant, p > 0.001) were observed during rainy-cold months of the year.

Comparison in systemic hypertension of left ventricular mass and geometry with systolic and diastolic function in patients <65 to > or = 65 years of age

Previous studies have differed on the independent effect of age and gender to left ventricular (LV) mass. Data on ventricular remodeling in hypertensive patients > or = 65 years of age is lacking. Similarly, the systolic and diastolic interaction in older hypertensives is not well defined. In a prospective study, we examined the relation of LV mass, relative wall thickness, and systolic and diastolic interaction in 508 hypertensive patients between 50 and 80 years of age who were divided according to age (<65 and > or = 65 years) and gender. LV mass, geometric classification, systolic wall stress, and Doppler filling were obtained according to standard Doppler echocardiographic criteria. In men, most measurements were similarly distributed. However, women > or = 65 years of age had smaller LV systolic dimensions, thicker ventricular septums, higher endocardial and midwall fractional shortenings, and lower end-systolic wall stress. Although LV mass was higher in men, there was no age difference within the same sex. The most common LV geometric remodeling was increased relative wall thickness in the form of concentric hypertrophy or concentric remodeled. The predominant mitral flow pattern was "impaired relaxation"; however, older patients had even shorter E waves, taller A waves, and lower E/A ratios. Thus, patients > or = 65 years of age had an even higher prevalence of this pattern (men, 89% vs 73%, p <0.001, and women, 91% vs 77%, p <0.001). Delayed LV relaxation with preservation of systolic ejection indexes is an early abnormality in essential hypertension, which lasts an undetermined time with further progression as patients aged. As a result, hypertensive patients > or = 65 years of age had the most pronounced structural and functional changes, an observation particularly noted in women. In those > or = 65 years, data from the Doppler E wave and A wave do not distinguish the physiologic process of aging from the pathologic changes of pressure overload.

Serotonin modulation of low-affinity ouabain binding in rat brain determined by quantitative autoradiography

Previous results showed that Na+/K+-ATPase may have a functional relationship with the neurotransmitter serotonin which activates the glial sodium pump in the rat brain. Both the reaction rate (V) of Na+/K+-ATPase activity and [3H]ouabain binding were significantly increased in the presence of serotonin. It is not known, however, which alpha isoform is involved in the Na+/K+-ATPase response to serotonin and its regional distribution. Quantitative autoradiography of [3H]ouabain binding to rat brain slices was employed at different [3H]ouabain concentrations in order to gain information on both the distribution and the possible isoform involved. The results showed that 1500 nM [3H]ouabain binding was sensitive to serotonin 10(-3) M and significantly increased in the following brain regions: frontal cortex, areas CA1, CA2, and CA3 of the hippocampus, presubiculum, zona incerta, caudate putamen and the amygdaloid area, confirming and extending previous results. An effect of serotonin on brain but not kidney tissue at high, 1500 nM, and the lack of effect at low, 50 nM [3H]ouabain concentrations, strongly suggests the participation of the alpha2 isoform in the response of the pump to the neurotransmitter. Glial cells showed stimulation of ouabain binding by serotonin at ouabain concentrations above 350 nM. The present results open interesting questions related to the brain regions involved and the K+ handling by the glial alpha2 isoform of the pump.

Regulated release of serotonin from axonal growth cones isolated from the fetal rat brain

In the present work we propose an hypothetical model related to a molecular recognizing system for serotonin in isolated growth cone particles. This model is supported by previous results from our laboratory plus new ones which show that growth cones release serotonin tonically and such release can be stimulated by potassium in a calcium-dependent manner. The present results, together with other author's data, suggest a physiological basis for the putative role of serotonin as a trophic factor during nervous system development.

Pattern of deletions of the dystrophin gene in Mexican Duchenne/Becker muscular dystrophy patients: the use of new designed primers for the analysis of the major deletion "hot spot" region

We have analyzed 59 unrelated Mexican Duchenne/Becker muscular dystrophy patients (DMD/BMD) using PCR analysis of the 2 prone deletion regions in the DMD gene. Thirty one (52%) of the patients had a deletion of one or several of the exons. Most of the alterations (87%) were clustered in exons 44-52, this being the highest percentage reported until now. In order to improve the molecular diagnosis in the Mexican population, we designed a new multiplex assay to PCR amplify exons 44-52. This assay allowed for the identification of a greater number of deletions in this region compared with the 9 and 5-plex assays previously described and to determine most of the deletion end boundaries. This is a reliable alternative for the initial screening of the DMD patients in the Mexican population.

Human case of gastric infection by a fourth larval stage of Pseudoterranova decipiens (Nematoda, Anisakidae)

Only three cases of human infection by anisakid nematodes have been reported in Chile since 1976. In the present case, an anisakid worm, identified as a fourth-stage Pseudoterranova decipiens larva, was removed with a gastroendoscopic biopsy clipper from the stomach of a 45 year-old man from southern Chile. The patient, who presented acute epigastric pain and a continuous sensation of having an empty stomach, reported having eaten smoked fish. The worm was fixed in 70% ethanol and cleaned in lactophenol for morphological study. The morphometric characteristics of the worm are described and drawn. Anisakid larvae in fish flesh can be killed by freezing or cooking.

[Human infection by intestinal protozoa and helminths in Calbuco County, X Region, Chile, 1997]

By the performance of parasitological examination of one fecal sample per individual, a total of 256 persons from a rural county in the X Region (41 degrees 50 minutes South lat., 73 degrees 05 minutes West long.) were studied. The general rates of infection by intestinal parasite and/or commensal protozoa and helminths found were: Giardia intestinalis 14.1%, Entamoeba histolytica 11.7%, Blastocystis hominis 36.0%, Entamoeba coli 9.8%, Endolimax nana 16.4%, Iodamoeba buetschlii 1.2%, Chilomastix mesnili 0.8%, Ascaris lumbricoides 13.7% and Trichuris trichiura 9.8%. The prevalence rates of intestinal infection led us to conclude that environmental conditions favorable for its transmission remain and show that intestinal parasitoses are still a public health problem in this region, affecting mostly children.

[Various epidemiological aspects of Enterobius vermicularis infection inpatients served at public outpatient clinics and hospitals from the northern section of Santiago, Chile, 1995]

During 1995, we examined 2,666 Graham's tests (five perianal swabs with adhesive cellulose tape) prescribed to ambulatory patients attended in 14 public outpatient clinics and four hospitals from the north section of Santiago. The infection rates found by age groups were the following: 6.1% in infants (< 2 years old), 20.9% in pre-schoolchildren (2 < 6 years old), 35.2% in elementary schoolchildren (6 < 15 years old) and 15.2% in adults (> 15 years old). Similar percentages of E. vermicularis infections were observed in females and males patients. Frequency of infection in each month of the year varied between 17.4 and 26.8%, with no seasonal variation. This study and previous surveys are stressing that E. vermicularis is the most frequent helminthic agent found in Chile, specially in elementary school children.

Radiofrequency field surveys in hospitals

The authors surveyed levels of radiofrequency (RF) fields in the frequency range 0.1-1,000 MHz in four hospitals in the Philadelphia area, to obtain background information related to the possible interference of radiofrequency fields with medical equipment. Two large center-city hospitals, a regional county hospital, and two suburban hospitals were surveyed. Measurements were made at six to 12 sites in each hospital, in each of the three frequency bands. More limited additional measurements were conducted in a fifth hospital as well. Sites were selected to include areas where strong RF signals from transmitting antennas might be expected to be present (e.g., locations close to windows in upper stories of buildings near paging antennas) as well as other representative sites in the hospital. The median RF field strengths were quite low (0.1-0.5 V/m), but at specific locations the RF signals from broadcast sources exceeded 1 V/m. Much stronger fields were recorded close to electrosurgical units and hand-held transmitters (cellular telephones and UHF transceivers).

[Taenia sp and other intestinal cestode infections in individuals from public outpatient clinics and hospitals from the northern section of Santiago, Chile (1985-1994)]

During 1985-1994 period, 70,642 parasitological stool examinations were performed. The exam was made to each patient which presenting gastrointestinal symptoms or nutritional problems, specially in children. 59,960 out of the 70,642 examinations corresponded to 1 month--15 years old children, 4,280 to 16-30 years old individuals and 6.402 to up to 30 years old adults. The infection rates (x 100,000) were: Taenia sp., 86; Hymenolepis nana, 1,165; Diphyllobotrium sp., 4 and Hymenolepis diminuta, 1. In this period, 11 cases of infection by Taenia saginata were detected, and none Taenia sodium infection. Although infections rates by intestinal cesdodes were higher in males than females, in the Taenia sp. infection the difference was not statistical significative. Médico-veterinary control of animals slaughtered in abbatoirs and the improvement of sanitary conditions in the last two decades have contributed to the control of most of human intestinal cestodiases.

[Annual frequency of Cryptosporidium parvum infections in children and adult outpatients, and adults infected by HIV]

We report the analysis of 4892 parasitological stool samples coming from outpatients and patients of a nutritional recuperation center of north Santiago. Cryptosporidium parvum was detected in 21 samples (0.4%). The protozoan was detected in 6 of 1203 samples from children of less than 2 years old, 3 of 1.727 samples from children between 6 and 15 years, none of 776 samples from healthy adults and 2 of 13 samples from HIV infected patients. Nine of 97 children of less than 2 years old, hospitalized in the nutritional recuperation center, were infected with Cryptosporidium; this frequency was significantly higher than that of outpatients of the same age. Most infections were detected from May to August, a rainy and mildly cold period. It is concluded that Cryptosporidium infections are infrequent in healthy outpatients and that its prevalence increased in hospitalized children and HIV infected adults.

Biochemical properties of Na+/K(+)-ATPase in axonal growth cone particles isolated from fetal rat brain

Axonal growth cones (AGC) isolated from fetal rat brain have an important specific activity of N+/K(+)-ATPase. Kinetic assays of the enzyme in AGC showed that Km values for ATP or K+ are similar to those reported for the adult brain enzyme. For Na+ the affinity (Km) was lower. Vmax for the three substrates was several times lower in AGC as compared to the adult value. We also observed two apparent inhibition constants of Na+/K(+)-ATPase by ouabain, one of low affinity, possibly corresponding to the alpha 1 isoform and another of high affinity which is different to that described for the alpha 2 isoform of the enzyme. These results support an important role for the sodium pump in the maintainance of volume and cationic balance in neuronal differentiating structures. The functional differences observed also suggest that the enzymatic complex of Na+/K(+)-ATPase in AGC is in a transitional state towards the adult configuration.

[Asymptomatic cryptosporidiosis in an infant]

A two year-old male who presented lack of appetite, mild coughing and one episode of vomiting was assisted in a pediatrics outpatient clinic. The parasitological examination of three stool samples of the patient revealed the presence of Cryptosporidium parvum oocysts. Fecal parasitological examination of his mother and a one year-old sister showed oocysts of the same protozoon in this last patient, who was asymptomatic. With no pharmacological treatment, parasitological stool examination, performed one month later on the two children, resulted negative, being the boy without any symptom.

[Epidemiology of Chagas' disease in Chile. Serological follow-up of 1,906 inhabitants from an endemic rural area, IV Region, 1991-1993]

The IV Region (29 degrees 30'-32 degrees 13' south lat.) is located in the center of the geographical area of distribution of Chagas' disease in Chile. Triatoma infestans is the main and almost exclusive vector of Trypanosoma cruzi in this country. The mean prevalence rate of T. cruzi human infection in urban and periurban sections of IV Region is 24.7%. To assess the impact of anti-T. infestans activities, by means of health education and sprayings of dwellings with insecticides, carried out in the IV Region since 1980, during January-February (summer) a serological follow-up to residents from 46 rural chagasic localities was performed. An indirect hemagglutination test and an indirect immunofluorescence test were done to each of the surveyed persons. In 1991, 303 (15.9%) out of 1,906 examined people resulted serologically positive. In 1992, previous discarding the positive individuals found in 1991, 1,334 persons were examined resulting positive 9 (0.7%). In 1993, 1,398 persons were surveyed and 26 (1.9%) were positive. It is noteworthy that none of these 35 positive persons had been surveyed in 1991, being difficult to assert if any was positive before. Two infants, daughters of positive mothers, serologically positive at the beginning, changed to negative in the following survey, indicating that it was a passive transfer of maternal specific antibodies. According to the results of this study, it is concluded that dwelling spraying with persistent-activity insecticides against T. infestans and health education are good tools in the control of T. cruzi human infection, particularly when the involved community participates.

[A modified Strout test, used as a probe for the diagnosis of transplacental Chagas disease. I. Collection and preservation of the newborn's umbilical cord blood]

Two umbilical cord (UC) blood samples are routinarily taken from each newborn (NB) at the University of Chile Maternity Hospital, to determine blood grouping and for detecting syphilis infection respectively. In august-september 1993, an additional UC blood sample was collected from each of 116 NB (with volumes of whole blood ranging 2.7 - 24.5 ml and a mean of 13.5 ml). In order to determine the persistence of the mobility of Trypanosoma cruzi in blood samples stored at three different temperatures (-2 to -4 degrees C, 4 to 6 degrees C and environmental temperature from 16 to 23 degrees C), two experiments were performed: 1) In three centrifuge microtubes mouse blood (C3H strain) abundant T. cruzi trypomastigotes Tulahuen strain were put. 2) In an other similar number of microtubes, with the same concentration of parasites, human serum from UC was added. During the first 12 h in all the samples trypomastigotes with very active mobility were observed. At 72 h mobility persisted in samples with temperature between 4 and 6 degrees C and between 16 and 23 degrees C. Whereas in the samples maintained at -2 to -4 degrees C with parasites in blood plus serum, an important decrease of T. cruzi mobility was observed. The results of this study suggest that UC blood samples could be collected and maintained between 4 and 6 degrees C or at room temperature up to 48 h to be processed by the modified Strout concentration method (MSCM).(ABSTRACT TRUNCATED AT 250 WORDS)

A molecular recognizing system of serotonin in rat fetal axonal growth cones: uptake and high affinity binding

Axonal growth cone particles (AGCP) isolated from prenatal and postnatal rat brain had different high-affinity 5-HT uptake characteristics. In postnatal AGCP the uptake behaves as in the adult rat brain, while in the prenatal AGCP the uptake characteristics seem to be in a transitional stage. Also in prenatal AGCP we observed specific, high-affinity 5-HT binding sites. These results support the idea of an important role for 5-HT during axogenesis.

[Absorption of human serum antibodies against Toxoplasma gondii using Tachyzoites from the RH strain]

Absorption experiments to determine the number of T. gondii tachyzoites to extract the anti-Toxoplasma antibodies present in the human serum were carried out. The antibodies titer from each serum (n = 4) was determined by means of the Sabin-Feldman test (dye test). Ten millions of tachyzoites were sufficient to absorb the antibodies from sera presenting titer 1:16, 1:64 and 1:256. On the other side, the absorption of a 1:512 positive serum with 10 x 10(6) T. gondii decreased the titer to 1:64 and the dye test became negative when using 50 x 10(6) tachyzoites.

Regulatory role of a neurotransmitter (5-HT) on glial Na+/K(+)-ATPase in the rat brain

In the present work we studied the effect of serotonin (5-HT) on the kinetics of Na+/K(+)-ATPase in subcellular preparations of the cerebral cortex from male Wistar rats using various concentrations of ATP and K+ with and without added 5-HT. Also we studied the effect of 5-HT on the enzyme in glial or neuronal preparations. The results indicated that there was a significant increase (P < 0.05) of the Vmax in the presence of 5-HT in the whole tissue preparation (homogenate) but not in the subcellular fractions, suggesting that the interaction could be preferentially with the glial pump. Further results supported that this was the case since activation by 5-HT was mainly in the glial preparations. Kinetic data and the binding of [3H]ouabain supported that the enzyme is activated by 5-HT through the exposure of more enzymatic active sites.

Effect of myotonia induced by anthracene-9-carboxylic acid on mitochondrial calcium, plasma creatinine-phosphokinase and aldolase activity in the rat

The frequent association of myotonia with dystrophy and the knowledge that calcium is increased in injured skeletal muscle cells suggest a possible relationship between cell calcium and myotonic alterations. This investigation has been performed to study the role of calcium in experimental myotonia induced by anthracene-9-carboxylic acid (9-AC) in rats treated with several regimens of food and exercise. Thirty-two rats were divided into 4 groups of 8 rats each, one control and 3 experimental groups. The treatments included caffeine plus exercise (group 2), and a calcium-rich diet (group 3); these procedures were designed to increase intracellular calcium; another group was treated with 9-AC as a myotonia-inducer (group 4). The treatment for all groups lasted 60 days. No significant differences in plasma sodium, potassium, chloride and calcium between control and experimental groups were observed. Whole muscle calcium in wet tissue samples did no change with any treatment. On the contrary, mitochondrial calcium showed a significantly higher concentration in group 3 and 4. CPK and aldolase activities in groups 1, 2 and 3 were similar; but in group 4 these enzyme activities were significantly higher (p less than 0.05). The electrical and mechanical responses were not altered in any rat with any experimental treatment. Our data suggest that myotonia is a predisposing factor for an altered mitochondrial calcium homeostasis in this model; in addition, the enzyme activities of CPK and aldolase were increased in the rats of group 4 implicating that myotonia is a crucial factor in the development of enzymatic abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

[Epidemiological and diagnostic aspects of human Cryptosporidiosis in Chile]

Cryptosporidium sp. infections have been reported in different Chilean localities, both in healthy individuals and immunocompromised patients. Among the first, hospitalized and ambulatory children less than 3 years old are the age group more affected reaching frequencies from 3.1 up to 19.3%. In pre-school children, school children and adults the prevalence rates have been 1.1, 0.2 and 0.3% respectively. According to the epidemiological studies carried out, the routine laboratory diagnosis of this parasitosis should be emphasized in the parasitological stool examinations in children under 3 years of age, and selectively in the older ones.

[Application of a system of serological surveillance of Chagas disease in a region of high chagasic endemia. I. Prevalence of Trypanosoma cruzi infection in Salamanca]

A serologic study for prevalence of Chagas infection was performed in Salamanca, Northern Chile. Indirect immunofluorescence and indirect hemagglutination reactions were used in samples from 1529 females and 698 males representing 10% of the population. A total of 499 positive results were obtained. The incidence of infection increases at a mean rate of 1% per year up to age 30, declining slowly in older groups to reach a maximum of 39.7% for the population. These data will be used to implement appropriate serologic surveillance programs and sanitary control measures in this and other populations.

[Isolation of Cryptosporidium sp. oocysts from human fecal samples]

Experiments using two sequential discontinuous sucrose gradients, performed with 12%, 18%, 21% and 24% solutions, for the isolation of Cryptosporidium sp. oocysts from human fecal samples were undertaken. The sucrose gradients were centrifuged at 4000 rpm during 20 min. at 10 degrees C or room temperature. After that, 3 bands were observed. Oocysts were recovered mainly from the second band (75.5% after the first gradient, and 44.4% in the next). The two sequential discontinuous sucrose gradients would permit an efficient isolation of Cryptosporidium sp. oocysts from human fecal samples.

[Blastocystis hominis: frequency of infection in ambulatory patients from the northern section of Santiago, Chile]

In July 1989-July 1990 period, a coproparasitological study of 6,162 ambulatory patients from the northern section of Santiago, was undertaken. Out of the total number of the studied individual, 88.6% were children, (51.4% females and 48.6% males). The global frequency of infection by B. hominis was 30.4%. In relation to age. Blastocystis hominis was found in: 13.1% of the group of children (1 month-2 years); 34.1% of the pre-school children, 45.4% in the school-children and 43.0% in the adults. B. hominis was frequently detected in association with other parasites and/or commensals, and observed alone in the 6.0% of the studied patients.

[Detection of immunoreactive peptides of Fasciola hepatica, with sera from infected subjects, by enzyme immunoelectrotransfer]

In order to observe the immunoreactive peptides in a crude extract of adult Fasciola hepatica specimens, proteins were separated by 10% sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and transferred to nitrocellulose paper. Next, sera from 14 human cases of F. hepatica infection, parasitologically confirmed, which presented high titers of specific antibodies against F. hepatica detected by ELISA, were reacted with the blotted peptides and immunodetected by an anti-human IgG conjugated with horse-radish peroxidase. SDS-PAGE showed at least 18 bands ranging 96 to 14 Kd. Groups of peptides weighing 94-66 Kd, 43-36 Kd and 35-14 Kd reacted with serum antibodies of 12 fascioliasis patients. In the remaining two cases, reactive peptides were not clearly observed. The 94-66 Kd components were immunoreactive with 12 out of the 14 serum samples. On the other hand, 43-36 Kd peptides reacted with 4 of the 14 sera and only 3 out of the 14 sera of infected individuals showed reaction with 30-14 Kd. F. hepatica infection induces in humans diverse antibody responses, being 94-66 Kd bands the most immunoreactive peptides and would be potential serodiagnostic antigens.

[Incidence of infection by intestinal parasites among school children in Santiago, Chile, 1988-1989]

In December 1988-February 1989 period, a survey on enteroparasitic infections in children (mean age 8.7 years; males 54.4% and females 45.6%) from five schools located in Santiago, Chile, was undertaken. To each of these individuals, three samples were obtained in order to perform in them the following examinations: co-proparasitological study, modified Ziehl-Neelsen staining for detecting Cryptosporidium sp. and cellulose adhesive test for Enterobius vermicularis. Parasitic elements were found in the following percentages: Blastocystis hominis 51.8, Enterobius vermicularis 39.9, Giardia lamblia 32.1, Entamoeba histolytica 7.8, Hymenolepis nana 2.1 and Ascaris lumbricoides 0.4, Cryptosporidium sp. were not observed. The present study would be demonstrating that enteroparasites maintain their endemic condition among school children from Santiago, including B. hominis which had not been searched previously.