Towards the physical map of the Trypanosoma cruzi nuclear genome: construction of YAC and BAC libraries of the reference clone T. cruzi CL-Brener

Strategies to construct the physical map of the Trypanosoma cruzi nuclear genome have to capitalize on three main advantages of the parasite genome, namely (a) its small size, (b) the fact that all chromosomes can be defined, and many of them can be isolated by pulse field gel electrophoresis, and (c) the fact that simple Southern blots of electrophoretic karyotypes can be used to map sequence tagged sites and expressed sequence tags to chromosomal bands. A major drawback to cope with is the complexity of T. cruzi genetics, that hinders the construction of a comprehensive genetic map. As a first step towards physical mapping, we report the construction and partial characterization of a T. cruzi CL-Brener genomic library in yeast artificial chromosomes (YACs) that consists of 2,770 individual YACs with a mean insert size of 365 kb encompassing around 10 genomic equivalents. Two libraries in bacterial artificial chromosomes (BACs) have been constructed, BACI and BACII. Both libraries represent about three genome equivalents. A third BAC library (BAC III) is being constructed. YACs and BACs are invaluable tools for physical mapping. More generally, they have to be considered as a common resource for research in Chagas disease.     

Injection of chemoattractants into normal cornea: a model of inflammation after alkali injury

PURPOSE: The objective of this study was to establish and characterize the invasion of polymorphonuclear leukocytes (PMNs) into a normal cornea after intrastromal injection of the tripeptide chemoattractants generated from alkali-degraded corneas. METHODS: The following samples were injected into the midstroma of normal rabbit corneas: ultrafiltered tripeptide chemoattractants (N-acetyl-proline-glycine-proline and N-methyl-proline-glycine-proline) generated from alkali-degraded corneas, synthetic N-acetyl-PGP, positive control (leukotriene B4 [LTB4]), or negative control (Hanks' balanced salt solution [HBSS]). Timed responses of PMN infiltration were established for effective concentrations of LTB4 or the ultrafiltered chemoattractants. RESULTS: All intrastromal injections resulted in the immediate development of an edematous disc that was 10 mm in diameter. The lesion essentially had cleared in the HBSS-injected eyes by 8 hours, and histologic sections revealed minimal numbers of PMNs in the cornea or limbal tissue. The injection of LTB4 or the ultrafiltered tripeptide chemoattractants induced peak numbers of PMNs within the stroma at 8 hours, subsiding by 16 hours. Seventy units of ultrafiltered chemoattractants yielded a strong PMN response, similar to 1 X 10(-5) M LTB4. The highest concentration of ultrafiltered chemoattractants (350 U) produced a severe PMN response that was characterized by a solid sheet of neutrophils surrounding the injection site. The injection of synthetic N-acetyl-PGP (2 X 10(-4) M) produced a marked PMN response. CONCLUSIONS: PMN invasion of the normal cornea after the injection of the ultrafiltered tripeptide chemoattractants or the synthetic N-acetyl-PGP mimicked early PMN infiltration in the alkali-injured eye, confirming the importance of this chemoattractant as an inflammatory mediator.     

Internal validity of Project MATCH treatments: discriminability and integrity

Project MATCH (Matching Alcoholism Treatments to Client Heterogeneity) is a multisite collaborative project designed to evaluate patient-treatment interactions in alcoholism treatment. To evaluate whether major threats to the internal validity of the independent (treatment) variable in Project MATCH could be ruled out, we investigated several aspects of treatment integrity and discriminability. In this study, 1,726 alcohol-dependent participants at 10 sites were randomized to 3 treatments: cognitive-behavioral treatment (CBT), motivational enhancement therapy (MET), and 12-step facilitation (TSF). Participants received treatment either as outpatients or as aftercare following a more intensive inpatient or day hospital treatment. For both the outpatient and aftercare arms of the study, treatments were discriminable in that therapists implemented each of the treatments according to manual guidelines and rarely used techniques associated with comparison approaches. Participants received a high level of exposure to their study treatments, and the intended contrast in treatment dose between MET and the 2 more intensive treatments (CBT and TSF) was obtained. Alcoholics Anonymous involvement was significantly higher for participants assigned to TSF versus MET or CBT, whereas the treatments did not differ in utilization of other nonstudy treatments. Nonspecific aspects of treatment such as therapist skillfulness and level of the therapeutic alliance were comparable across treatment conditions.     

Xrcc3 is required for assembly of Rad51 complexes in vivo

Rad51 is a member of a family of eukaryotic proteins related to the bacterial recombinational repair protein RecA. Rad51 protein localizes to multiple subnuclear foci in Chinese hamster ovary cells. Subnuclear Rad51 foci are induced by ionizing radiation or the DNA cross-linking agent cisplatin. Formation of these foci is likely to reflect assembly of a multimeric form of Rad51 that promotes DNA repair. Formation of damage-induced Rad51 foci does not occur in the Chinese hamster ovary cell line irs1SF, which is sensitive to DNA damaging agents. The Rad51 focus formation defect of irs1SF cells is corrected by a construct that encodes the repair protein Xrcc3. Xrcc3 is a human homolog of Rad51 previously isolated by virtue of its ability to correct the radiation sensitivity of irs1SF cells. Changes in the steady state level of Rad51 protein do not account for the irs1SF defect nor do they account for the appearance of foci following DNA damage. These results suggest that Xrcc3 is required for the assembly or stabilization of a multimeric form of Rad51 during DNA repair. Cell lines defective in two different components of DNA protein kinase formed Rad51 foci in response to damage, indicating DNA protein kinase is not required for damaged-induced mobilization of Rad51.     

Determinants of heart rate variability during deep breathing: basic findings and clinical applications

Clinical laboratory evaluation of congenital hemoglobin disorders requires both the accurate identification of major and minor hemoglobin variants, and precise quantitation of these variants over a wide range of concentrations. Capillary isoelectric focusing is an automated, microanalytical technique that produces diagnostic information comparable to that obtained from multiple conventional assays now used by most hospital laboratories. This report describes the advantages of capillary isoelectric focusing for the routine primary assessment of hemoglobinopathies and thalassemias. The use of capillary isoelectric focusing for the identification of unusual hemoglobinopathies, including an extremely rare doubly heterozygous disorder (hemoglobin C/E disease), is described. Application of the technique for rapid (< 4 minutes) neonatal hemoglobinopathy screening, and for the analysis of Hb A1c to monitor glycemic control in diabetic subjects is also discussed. In an increasingly competitive and cost-conscious clinical diagnostic market, capillary isoelectric focusing is a rapid, specific, precise, and low-cost method for comprehensive primary analysis of hemoglobin variants.     

Does the presence of a pre-ileostomy closure asymptomatic pouch-anastomotic sinus tract affect the success of ileal pouch-anal anastomosis?

Ileal pouch-anal anastomosis (IPAA) is the procedure of choice for patients with ulcerative colitis and familial adenomatous polyposis. This two-stage procedure with a temporary diverting ileostomy avoids the catastrophic consequences of anastomotic leakage. We set out to determine the incidence and effect of asymptomatic pouch sinuses detected prior to ileostomy closure on the outcome of IPAA. A total 1600 IPAAs performed at the Mayo Clinic were reviewed. Forty-one (2.6%) asymptomatic sinuses were treated expectantly. There were 22 males and 19 females who had a median age of 32 years (range 14 to 58 years). The median time to ileostomy closure was 5.9 months (range 4 to 11 months). Five patients required further surgery following closure of ileostomy. The pouch function in these five patients was similar to that in the remainder of the group. Patients with a persistent sinus at the time of ileostomy closure had the same function as the main cohort. This group had a median of five (range 2 to 12) stools during the day and two (range 0 to 4) at night. The total number of stools per 24 hours was seven (range 2 to 14). Frequent incontinence occurred in 9.7% and 7.3% during the day and at night, respectively. Only 2.4% (1/41) were disappointed with the results of the operation and 80.4% (33/41) found their quality of life improved. Functional outcomes were comparable to those achieved with uncomplicated IPAA. Radiologically detected asymptomatic sinuses can be treated expectantly with a low rate of pouch loss and subsequent surgery. This is not considered a serious setback inasmuch as long-term function and quality of life are comparable to that achieved with IPAA without sinus tracts.     

A dinucleotide deletion results in defective membrane anchoring and circulating soluble glycoprotein Ib alpha in a novel form of Bernard-Soulier syndrome

The platelet membrane glycoprotein (GP)Ib-V-IX complex is the receptor for von Willebrand factor and is composed of four membrane-spanning polypeptides: GPIb alpha, GPIb beta, GPIX, and GPV. A qualitative or quantitative deficiency in the GPIb-V-IX complex on the platelet membrane is the cause of the congenital platelet disorder Bernard-Soulier syndrome (BSS). We describe the molecular basis of a novel variant BSS in a patient in which GPIb alpha was absent from the platelet surface but present in a soluble form in the plasma. DNA sequence analysis showed a homozygous dinucleotide deletion in the codon for Tyr 508 (TAT) in GPIb alpha. This mutation (GPIb alpha deltaAT) causes a frame shift that alters the amino acid sequence of GPIb alpha within its transmembrane region. The hydrophobic nature of the predicted transmembrane region and the cytoplasmic tail at the COOH terminal are altered before reaching a new premature stop codon 38 amino acids short of the wild-type peptide. Although GPIb alpha deltaAT was not detectable on the platelet surface, immunoprecipitation of plasma with specific monoclonal antibodies (MoAbs) identified circulating GPIb alpha. Transient expression of recombinant GPIb alpha deltaAT in 293T cells also generated a soluble form of the protein. Moreover, when a plasmid encoding GPIb alpha deltaAT was transiently transfected into Chinese hamster ovary (CHO) cells stably expressing the GP beta-IX complex, it failed to be expressed on the cell surface. Thus, a dinucleotide deletion in the codon for Tyr 508 causes a frameshift that alters the amino acid sequence of GPIb alpha starting within its transmembrane region, changes the hydrophobicity of the normal transmembrane region, and truncates the cytoplasmic domain affecting binding to the cytoskeleton and cytoplasmic proteins. This mutation affects anchoring of the GPIb alpha polypeptide in platelets and causes the observed BSS phenotype with circulating soluble GPIb alpha.     

Psychiatric disorder among American Indian adolescents: prevalence in Northern Plains youth

This article presents data on the prevalence of psychiatric disorders among American Indian adolescents, using DSM-III-R criteria. OBJECTIVE: To generate current prevalence data using a structured diagnostic instrument, the Diagnostic Interview Schedule for Children, Version 2.1C (DISC-2.1C). METHODS: Youths from a Northern Plains tribe who had participated in an earlier study comprised the sample. At reinterview, respondents were between 14 and 16 years of age, when Indian adolescents are thought to be at particularly high risk for manifesting emotional disorders. One hundred nine of the original sample of 251 were still in schools on the reservation. Trained indigenous lay interviewers administered the DISC-2.1C to respondents in a private setting within the school. RESULTS: The findings indicate that rates of some psychiatric problems (e.g., disruptive behavior disorders, substance-related disorders, and their comorbidity) are high among these high school students. CONCLUSIONS: These data, as well as national statistics, suggest that, compared with non-Indian populations, a greater percentage of Northern Plains adolescents manifest significant psychiatric symptoms which warrant treatment.     

Effects of botulinum neurotoxin type A on abducens motoneurons in the cat: ultrastructural and synaptic alterations

The synaptic alterations induced in abducens motoneurons by the injection of 3 ng/kg of botulinum neurotoxin type A into the lateral rectus muscle were studied using ultrastructural and electrophysiological techniques. Motoneurons identified by the retrograde transport of horseradish peroxidase showed a progressive synaptic stripping already noticeable by four days post-injection which increased over the study period. By 35 days post-injection, the normal coverage of motoneurons by synaptic boutons (66.4 +/- 4.0%) significantly decreased to 27.2 +/- 4.0%. Synaptic boutons detached by a widening of the subsynaptic space but remained apposed by synaptic contacts and desmosomes to the motoneuron. Detachment did not affect equally flat and round vesicle-containing boutons. The control motoneuron had almost equal numbers of both types of boutons, but after 35 days post-injection the ratio of round to flat vesicle-containing boutons was 1.20 +/- 0.01. Synaptic boutons impinging on motoneurons showed signs of alterations in membrane turnover, as indicated by an increase in the number of synaptic vesicles and a decrease in the number of coated vesicles and synaptic vesicles near the active zone. Abducens motoneurons had a transient increase in soma size by 15 days that returned to normal at 35 days, but no signs of chromatolysis or organelle degeneration were seen. Accompanying the swelling of motoneurons, a 15-fold increase in the number of spines, very infrequent in controls, was observed. Spines located in the soma and proximal dendritic trunk received synaptic contacts from both flat and round vesicle-containing boutons that could be either partly detached or completely attached to the motoneuron. An increased turnover of the plasmatic membrane of the motoneuron was observed, as indicated by a four-fold increase in the number of somatic coated vesicles. Animals were implanted with bipolar electrodes in the ampulla of both horizontal semicircular canals for evoking contralateral excitatory and ipsilateral inhibitory postsynaptic potentials. Motoneurons were antidromically identified from the lateral rectus muscle. Synaptic potentials of vestibular origin were recorded in abducens motoneurons. In the period between two and six days post-injection, a complete abolition of inhibitory synaptic potentials was observed. By contrast, excitatory synaptic potentials remained, but were reduced by 82%. The imbalance between excitatory and inhibitory inputs to motoneurons induced a progressive increase of firing frequency within a few stimuli applied to the contralateral canal. Between 7 and 15 days post-injection, both excitatory and inhibitory postsynaptic potentials were virtually abolished and remained so up to the longest time checked (105 days). Some motoneurons recorded beyond 60 days post-injection showed signs of recovery of excitatory postsynaptic potentials. During the whole time-span studied, presynaptic wavelets were present, indicating no affecting of the conduction of afferent volleys to the abducens nucleus. Taken together, these data indicate that botulinum neurotoxin at high doses causes profound synaptic alterations in motoneurons responsible for the effects seen in the behavior of motoneurons recorded in alert animals.     

Noninvasive perfusion MRI in Alzheimer's disease: a preliminary report

We performed functional MRI using the echo-planar imaging and signal targeting with alternating radio frequency (EPISTAR) technique in 11 patients with Alzheimer's disease (AD) and 8 age-matched control subjects. Seven of the AD patients had qualitatively apparent focal areas of hypoperfusion in the posterior temporoparietal-occipital regions. At the earliest inversion time producing cortical enhancement, the ratios of parieto-occipital and temporo-occipital to whole slice signal intensity were significantly lower in the AD patients than in the controls. Parieto-occipital hypoperfusion correlated with dementia severity as measured by the Blessed Dementia Scale. EPISTAR may prove to be a rapid, noninvasive alternative to other functional neuroimaging modalities in the evaluation of patients with dementia.