Biological characterization of Trypanosoma cruzi stocks from Chilean insect vectors

Fifty-seven Trypanosoma cruzi stocks isolated from Triatoma infestans and Triatoma spinolai of the five different geographic endemic areas of Chile were studied by schizodeme and molecular karyotype analysis. Four different genotypes are found in the sylvatic T. spinolai vector and five in the T. infestans domiciliary vector. Of these genotypes, two common genotypes overlap on both transmission cycles exclusively in the extreme northern endemic areas of Chile. Metacyclic trypomastigotes obtained in vitro or cell-derived trypomastigotes proved to be infective in gamma-irradiated Balb/c mice for the study of the immune response and biological behavior. Of a total of 57 T. cruzi stocks obtained, 19 of them, representing all the different genotypes found in Chile, were tested on a murine experimental model and then fully studied. Female compared with male animals demonstrated greater resistance to Chagas disease with all the T. cruzi stocks tested. The immune response was assessed by lytic antibodies that were studied by the in vitro antibody-dependent complement-mediated lytic assay with the use of bloodstream trypomastigotes as target cells. In one unique parasite genotype the elicited lytic antibodies reacted in a genotype-specific manner, in contrast with lytic antibodies generated by other T. cruzi genotypes. Parasitemias were high, moderate, and low, with mortality ranges of 6-50%, 0-45%, and 0-10%, respectively. No association was found between specific infective genotypes and virulence or mortality. Independently of the T. cruzi strain studied, each population displayed a characteristic parasitemia curve and prepatent period. A considerable number of the parasite stocks proved to be mixed populations, according to molecular karyotype patterns obtained before and after differentiation and amplification of the parasites. This fact created difficulty in assessing the identity of the genotype really infective to mice.

Lytic antibodies in Trypanosoma cruzi-infected persons with low parasitemia

An antibody-dependent, complement-mediated lysis test performed with three Chilean trypomastigote strains used as target cells revealed strain dependence in the detection of lytic antibodies in chronic chagasic sera. The highest percentage of lytic sera was observed when MF or V115 strains were used as target cells (90% and 71%, respectively) in the chronic chagasic group with negative xenodiagnosis results. No significant statistical association was observed between lytic activity in chronic chagasic sera and the presence or absence of cardiopathy (P > 0.01). Western blot analysis showed that lytic sera recognize different antigens depending on the strain used and nonlytic sera had a weaker capacity to detect them.

Study of the behavioral effects of bilateral nucleus accumbens lesions on amphetamine and apomorphine in adult cats

The aim of the present work was to study the effects of three different types of bilateral lesions performed on the nucleus accumbens, upon the behaviors elicited in adult cats by parenteral administration of amphetamine and apomorphine, and to obtain an understanding of the functional role played by the cited structure. To this end, 10 cats received bilateral injections of 6-OHDA, 18 microg in each accumbens; 8 cats received a similar treatment with ibotenic acid (20 microg), and 11 cats were submitted to bilateral electrolytic damage. Before and after performing these lesions, in separate sessions, amphetamine (2.5 mg/kg SC) and apomorphine (2.0 mg/kg SC) were administered and their respective behaviors were compared. Besides, in a group of 10 cats, 6 of them were bilaterally injected with the above cited dose of 6-OHDA into the accumbens to determine dopamine concentration and the other four served as control. In three cats, ibotenic acid (20 microg) was unilaterally injected into the accumbens for histological analysis. The contralateral structure served as control. Finally, four cats were sham operated. The results obtained show that the accumbens in cats participates in locomotion, in stereotyped motor behaviors, and in emotional fear-like behavior. Its role in the production of motor behaviors apparently is not as important as has been reported in rodents.

Does intelligence account for the link between maternal literacy and child survival?

The strong and consistent correlation between maternal education and child health is now well known, and numerous studies have shown that wealth and income cannot explain the link. Policy-makers have therefore assumed that the relationship is causal and explicitly advocate schooling as a child health intervention. However, there are other factors which could account for the apparent effect of maternal education on child morbidity and mortality, one of which is intelligence. This paper examines the effect of maternal intelligence on child health and looks at the degree to which it can explain the literacy associations with child survival and risk of malnutrition. The data are from a retrospective cohort study of 1294 mothers and their 7475 offspring, of whom 454 were women who had learned to read and write as adults in Nicaragua's literacy programme, 457 were illiterate, and 383 had become literate as young girls attending school. The women's intelligence was tested using Raven's Coloured Progressive Matrices. Acquisition of literacy was strongly related to intelligence. Statistically significant associations with maternal literacy were found for under five mortality, infant mortality, and the risk of low mid-upper-arm circumference (MUAC) for age, before and after controlling for a wide range of socio-economic factors. Under five, child (one to four years), infant and post-neonatal mortality plus the risk of low height for age were significantly correlated with intelligence, but only with infant and under mortality rates did the association remain significant after controlling for socio-economic factors. A significant interaction between intelligence and literacy for under five mortality was due to literacy having a strong effect in the women of low intelligence, and a negligible effect among those of high intelligence. This study provides evidence that intelligence is an important determinant of child health among the illiterate, and that education may have the greatest impact on child health for mothers of relatively low intelligence.

Accumulation of defective viral genomes in peripheral blood mononuclear cells of human immunodeficiency virus type 1-infected individuals

Human immunodeficiency virus type 1 (HIV-1) genomes present in peripheral blood mononuclear cells (PBMCs) of infected persons or in lymphocytes infected in vitro were studied by long-distance PCR (LD-PCR) using primers localized in the HIV-1 long terminal repeats. The full-length 9-kb DNA was the only LD-PCR product obtained in peripheral and cord blood lymphocytes from seronegative donors infected in vitro. However, a high proportion (27% to 66%) of distinct populations of extensively deleted HIV-1 genomes of variable size was detected in PBMCs of 15 of 16 HIV-1-infected persons. Physical mapping of defective genomes showed that the frequency of deletions is proportional to their proximity to the central part of HIV-1 genome, which is consistent with a deletion mechanism involving a single polymerase jump during reverse transcription. Sequencing of deletion junctions revealed the presence of short direct repeats of three or four nucleotides. The number of defective HIV-1 genomes decreased after in vitro activation of PBMCs. Persistence of full-length and deleted genomes in in vitro activated PBMCs correlated with isolation of an infectious virus. Our results represent the first quantitative assessment of intragenomic rearrangements in HIV-1 genomes in PBMCs of infected persons and demonstrate that, in contrast to in vitro infection, defective genomes accumulate in PBMCs of infected persons.

Renal tubular acidosis in children with vesicoureteral reflux

PURPOSE

We evaluated renal tubular acidosis in children with primary vesicoureteral reflux.

MATERIALS AND METHODS

We studied 18 children 4 to 15 years old to determine age at onset, reflux intensity, and renal scars and volume as possible associated factors of renal tubular acidosis. Patients had normal glomerular filtration rates and no urinary infections for the last 12 weeks, and they had not undergone urological surgery. Urine acidification and alkalization tests were done, and the Mann-Whitney U test was used to assess differences between the groups with and without renal tubular acidosis.

RESULTS

A total of 14 patients had unilateral and 4 had bilateral reflux, which varied in severity. All children except 2 had renal scarring. Bilateral renal volume was smaller in the renal tubular acidosis group. Nine patients had distal renal tubular acidosis, including 4 with short stature.

CONCLUSIONS

Several patients with vesicoureteral reflux had renal tubular acidosis and some had growth failure. Grades of reflux and renal scarring were similar in patients with and without renal tubular acidosis. A single evaluation of reflux is of slight value for predicting future functional tubular impairment, and the duration of reflux and other associated factors may be more important. Renal tubular acidosis was the main explanation for growth failure in these patients.

Omeprazole in the long-term treatment of gastro-oesophageal reflux disease. A double-blind randomized dose-finding study

BACKGROUND

Omeprazole is effective in the treatment of reflux oesophagitis, and it is important to determine the lower dose limit with still appropriate clinical efficacy.

METHODS

Patients with endoscopic oesophagitis grade 1-4 (N = 220) were randomized to double-blind treatment with 20 mg or 40 mg omeprazole daily for 4-8 weeks. Those healed after this initial treatment phase were re-randomized to double-blind treatment with 20 mg omeprazole daily (n = 67), 10 mg omeprazole daily (n = 68), or placebo (n = 33) for 6 months. Remission was defined as the absence of any endoscopic sign of oesophagitis.

RESULTS

Healing rates were increased with 40 mg omeprazole, the therapeutic gain compared with the 20-mg dose being 15% after 4 and 8 weeks. The proportion of patients in remission after 6 months was 59% with 20 mg omeprazole, 35% with 10 mg omeprazole, and 0% with placebo.

CONCLUSION

Maintenance treatment with 10 mg omeprazole can prevent recurrence of oesophagitis in about one-third of patients with all grades of oesophagitis, and 20 mg omeprazole in about twice as many.

Lack of cross-reactivity of lytic antibodies with bloodstream forms of Trypanosoma cruzi zymodemes generated in a mouse experimental model

Immune sera from mice infected with specific Zymodemes of Trypanosoma cruzi parasites displayed preferential in vitro complement-mediated trypanolytic activity with homologous or genetically related bloodstream trypomastigotes. Culture-derived and metacyclic trypomastigotes were more susceptible to lytic antibodies than bloodstream trypomastigote forms when the same serum panel was tested. Different levels of maximal trypanolytic reaction were observed when several parasites and sera were tested, suggesting that T. cruzi stocks are dissimilar in their efficiency to evade the lytic reaction, probably by capping and shedding mechanisms. A discussion based on the heterogeneity of surface antigens able to elicit the lytic response among different T. cruzi populations is presented.

Aminoacyl-RNA synthesis catalyzed by an RNA

An RNA has been selected that rapidly aminoacylates its 2'(3') terminus when provided with phenylalanyl-adenosine monophosphate. That is, the RNA accelerates the same aminoacyl group transfer catalyzed by protein aminoacyl-transfer RNA synthetases. The best characterized RNA reaction requires both Mg2+ and Ca2+. These results confirm a necessary prediction of the RNA world hypothesis and represent efficient RNA reaction (> or = 10(5) times accelerated) at a carbonyl carbon, exemplifying a little explored type of RNA catalysis.

How parents cope with the experience of neonatal intensive care

Thirty-two mothers and 25 fathers described their coping efforts during the initial weeks of their preterm infants' hospitalization in a neonatal intensive care unit. Utilizing procedures developed by Lazarus and Folkman (1984) in which coping is linked with a specific stressful event, parents reported what they did to cope with the stressor they perceived to be the most stressful. They also completed the Ways of Coping Questionnaire (Folkman & Lazarus, 1988). Results showed that there were similarities and differences in the types of coping strategies used by mothers and fathers. In addition, factors such as neonatal morbidity and appraisal of control were differentially associated with the use of certain types of coping strategies. Implications for future research and clinical practice are discussed.

Human nasal mucosal changes after exposure to urban pollution

Millions of people worldwide are living in areas where ozone (O3) concentrations exceed health standards (an hourly average of 235 micrograms/m3/0.12 ppm, not to be exceeded more than once per year). Ozone induces acute nasal inflammatory responses and significant epithelial lesions in experimental animals and humans. To determine the nasal effects of a 15-day exposure to an urban polluted atmosphere with O3 as the main pollutant, we studied a population of healthy, young males newly arrived to southwest metropolitan Mexico City (SWMMC). The study included 49 non-smoking residents in an unpolluted port, Veracruz City; 14 subjects stayed in the port and served as controls, while 35 subjects traveled to SWMMC and had serial nasal lavages at different times after arriving in SWMMC. Subjects had exposures to ambient O3 an average of 10.2 hr/day, with a total cumulative O3 exposure of 10.644 ppm.hr. Nasal inflammatory responses, polymorphonuclear leukocyte PMN-CD11b surface expression, rhinoscopic changes, and respiratory symptoms were evaluated. Exposed subjects had massive nasal epithelial shedding and significant responses in PMN nasal influx (p < 0.00001) and in PMN-CD11b expression (p < 0.05). Cumulative O3 exposure correlated with respiratory symptoms, PMNs (rs = 0.2374, p < 0.01), and CD11b (rs = 0.3094, p < 0.01); 94% of exposed subjects experienced respiratory symptoms, and 97% left the city with an abnormal nasal mucosa by rhinoscopy. Nasal epithelial changes persisted 2 weeks after the exposed subjects returned to their nonpolluted environment. Exposure to an urban polluted atmosphere induces significant and persistent nasal epithelial alterations in healthy subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of abasic sites on bacteriophage T7 protein synthesis

We have examined protein synthesis directed by bacteriophage T7 which had been alkylated with methyl methanesulfonate so as to produce apurinic sites in its DNA in vivo. Both repair-proficient and repair-deficient (xth nfo mutant) strains of Escherichia coli served as host cells. In repair-proficient cells, all three classes of phage proteins were synthesized, although with significant delays. In mutant cells, only class I proteins were produced and their synthesis was delayed and reduced, demonstrating a perturbation of protein synthesis and providing the first in vivo indication that transcription is inhibited by abasic sites. However, the proposed effects of abasic sites on transcription appear to be weaker than those on replication.

Angiographic diagnosis and management of gastrointestinal hemorrhage. Current concepts

Gastrointestinal bleeding is now seen less often by the angiographer than in the past, owing to advances in pharmacology, endoscopy, and nuclear medicine. When patients with gastrointestinal bleeding are referred, it is often for therapy as well as diagnosis. Therapeutic options include infusion of vasoconstrictors and selective embolization, which is usually faster and more definitive. Depending on the agent used, embolization is generally quite safe and effective. The risk of ischemia is significant only in the colon or when collateral pathways have been previously interrupted. The management of variceal bleeding has changed significantly due to the advent of TIPS and the increasing availability of liver transplantation.

Transcription by T7 RNA polymerase of DNA containing abasic sites

The effects of abasic (AP) sites on RNA synthesis were studied in vitro, using T7 RNA polymerase and a plasmid template containing a T7 promoter. The presence of increasing numbers of AP sites caused a progressive decline in RNA synthesis. The average RNA chain length, calculated from the ratio of initiation to chain elongation, decreased with increasing numbers of AP sites, revealing that complete blocks must occur during synthesis. The probability that RNA polymerase would be blocked at an AP site in the DNA template strand was estimated to be 0.3 in our experimental conditions. These results demonstrate that RNA synthesis by T7 RNA polymerase is inhibited by AP sites and that readthrough of the lesion occurs more frequently than premature chain termination. Chemical reduction of AP sites in the template did not change the block/bypass pattern.

The use of perfluorocarbon liquids in the repositioning of posteriorly dislocated intraocular lenses

PURPOSE

Removal of intraocular lenses (IOLs) dislocated into the vitreous cavity can be hazardous and result in severe complications and visual loss. Recognizing limitations in current management, the authors developed a new, safer surgical technique to reduce intraoperative and postoperative complications.

METHODS

The authors report eight eyes of eight patients with posteriorly dislocated IOLs in which perfluorocarbon liquids were injected into the eye after vitrectomy to float the IOL off the retina. The IOL haptics were repositioned in the residual capsular bag or ciliary sulcus, and the positioning holes of the optic were sutured to the sclerotomies under a scleral flap.

RESULTS

With a minimum follow-up of 8 months (average, 12 months), all eight eyes improved in Snellen visual acuity, and six of them achieved a final Snellen visual acuity of 20/40 or better. Complications did not occur in any of the eight eyes. Preoperative cystoid macular edema resolved in three of four eyes, and the retina has remained attached in the one eye with a preoperative retinal detachment.

CONCLUSION

Application of vitreoretinal microsurgical techniques and the use of liquid perfluorocarbons allow for the safer management of eyes with posteriorly dislocated IOLs.

Expression of unusual immunophenotype combinations in acute myelogenous leukemia

Immunophenotypes for 272 patients with acute myelogenous leukemia (AML) were analyzed using a panel of 22 antibodies. Numerical evidence for unusual coexpressions (present in normal marrow at < or = 0.1%) of surface markers on > or = 10% of the blast cells was found in 85% of all cases. Asynchronous expression of myeloid differentiation antigens occurred in 70% of the cases. Unusual coexpression of T-lymphoid, B-lymphoid, or natural killer (NK) markers with myeloid markers occurred in 38%, 13%, and 21%, respectively, of all AML cases. Two- and three-color analyses confirmed coexpression in 15 of 15 cases, and indicated that these percentages are an underestimate, because coexpression can be demonstrated in cases without numerical overlap. These data indicate that the unusual coexpression of normal differentiation antigens is a common occurrence in AML. Markers in 12 of 13 patients were similar between presentation and relapse, and in two patients, unusual phenotypes detected at first relapse were shown at second relapse, indicating these immunophenotypes are stable in the majority of AML patients. Significant correlations were found between t(8;21) cytogenetics and coexpression of CD19 with CD15 or CD34, t(9;22) and coexpression of CD19 and CD34, and t(15;17) and coexpression of CD2 and myeloid antigens. Multiparameter fluorescence analysis allows detection of unusual phenotypes when the blast counts are < 5% (classical remission). Analysis of 16 patients in remission indicated the presence of presentation phenotypes in 0.2% to 7.9% of the lymphocyte + blast light scatter region, representing 0.03% to 1.4% of the total nucleated marrow cells. Of the 16 patients with > or = 4 months follow-up after detection of these cells, 6 of 6 patients with > or = 0.2% unusual presentation phenotypic marrow cells have relapsed, while 9 of 10 patients with < 0.2% remain in remission. The detection of cells with the unusual presentation phenotype may reflect residual AML cells, and their increase may predict relapse.

Development of T7 phage and T7 phage containing apurinic sites in an exonuclease III, endonuclease IV double mutant of Escherichia coli

The development of bacteriophage T7 was examined in an Escherichia coli double mutant defective for the two major apurinic, apyrimidinic endonucleases (exonuclease III and endonuclease IV, xth nfo). In cells infected with phages containing apurinic sites, the defect in repair enzymes led to a decrease of phage survival and a total absence of bacterial DNA degradation and of phage DNA synthesis. These results directly demonstrate the toxic action of apurinic sites on bacteriophage T7 at the intracellular level and its alleviation by DNA repair. In addition, untreated T7 phage unexpectedly displayed reduced plating efficiency and decreased DNA synthesis in the xth nfo double mutant.

Impaired atrial natriuretic factor systemic clearance contributes to its higher levels in uremia

To evaluate the interaction between plasma levels and the systemic uptake of atrial natriuretic factor (ANF) with thyroid hormone levels during acute renal failure (ARF), seven groups of rats were analyzed: Group 1, Controls (C); Group 2, ARF; Group 3, filtering kidney with uremia; Group 4, ARF with thyroxine (T4) supplement (ARF + T4); Group 5, thyroidectomy (Tx); Group 6, ARF on Tx rats (Tx + ARF); Group 7, Tx + ARF supplemented with T4 (Tx + ARF + T4). Plasma creatinine (Cr), urea, T4, blood volume, and ANF were measured; ANF half-life (ANF t1/2; expressed in seconds) was calculated. Rats with ARF developed uremia (Cr, 377 +/- 58 versus 41 +/- 5 mumol/L), significant reduction in T4 (40 +/- 4 versus 89.2 +/- 6 nmol/L). elevation of ANF (287.7 +/- 35 versus 60.9 +/- 8 fmol/mL), and lengthening of ANF t1/2 (69.7 +/- 8 versus 37.2 +/- 6 s) compared with C (P less than 0.01). T4 supplements to ARF rats resulted in a lesser degree of uremia (Cr, 283 +/- 27; P less than 0.05) and normalization of ANF t1/2 (31.4 +/- 5); however, ANF levels remained higher than C (100.4 +/- 11.4 versus 60.9 +/- 8; P less than 0.01). Tx by itself did not change either parameter. The filtering kidney with uremia group developed mild uremia (Cr, 199 +/- 8), T4 fell (58 +/- 8), ANF levels rose (83.4 +/- 5.4), and ANF t1/2 was prolonged (54.5 +/- 12). Tx before ARF doubled the ANF level and lengthened ANF t1/2 similarly than in ARF. T4 addition (Tx + ARF + T4) normalized ANF t1/2 (29.8 +/- 3) in spite of a persistently high ANF (145.7 +/- 21). Blood volume did not change in any group.(ABSTRACT TRUNCATED AT 250 WORDS)

A rare case of a multicentric peripheral ameloblastoma of the gingiva. A light and electron microscopic study

A rare case of a multicentric peripheral ameloblastoma of the gingiva in a 54-year-old male patient is described along with a light and electron microscopic study of the excised tumors. The peripheral ameloblastoma is considered to be the gingival counterpart of the more common intraosseous ameloblastoma. Although both tumors have similar histomorphologic characteristics, their clinical appearance and behavior are completely different. The peripheral ameloblastoma is slow growing and non-invasive, and recurrence is uncommon following excision. The more common central ameloblastoma, is locally invasive and can destroy large segments of the jaw. The histogenesis of the peripheral ameloblastoma and several other odontogenic tumors of the gingiva serves to illustrate the proliferative potential of the basal cell layer of gingival epithelium.

Reactivity patterns and infection status of serum samples with indeterminate Western immunoblot tests for antibody to human immunodeficiency virus type 1

Serum samples with indeterminate Western blot (WB) tests from 61 individuals whose sera were positive by enzyme-linked immunosorbent assay (ELISA) were studied in order to characterize their putative reactions with the human immunodeficiency virus (HIV) proteins and to resolve the HIV infection status of these individuals. The reaction observed by WB could not be confirmed either by radioimmunoprecipitation assay and subsequent electrophoresis (RIPA) or by use of LiaTek (Organon Teknika, Turnbout, The Netherlands) in 28% of the samples. Of the 86 samples that were indeterminate by WB, 66 reacted with p24 by WB; this reaction was confirmed by RIPA in only 21 (32%) and by LiaTek in 49 (74%) of the 66 samples. On the other hand, none of the indeterminate samples that reacted with HIV envelope proteins by WB did so by LiaTek, while 50% precipitated at least some of these proteins in the RIPA. The sensitivities of the three methods for detecting the antibody reaction with the different HIV proteins, which were studied with serial dilutions of positive serum samples, were similar. Thus, a lower sensitivity of RIPA or LiaTek does not seem to be the cause for the lack of reaction of the WB-indeterminate samples by these two methods. Sequential samples from individuals whose serum samples reacted by the three methods gave reproducible results, but all showed low antibody titers. Peripheral blood mononuclear cells obtained from three of the four individuals with sequential samples that reacted with HIV env proteins by WB and RIPA were negative for HIV provirus DNA after amplification by the polymerase chain reaction.