A mouse model of spinal and bulbar muscular atrophy

Spinal and bulbar muscular atrophy (SBMA) is an adult-onset motor neuron disease, caused by the expansion of a trinucleotide repeat (TNR) in exon 1 of the androgen receptor (AR) gene. This disorder is characterized by degeneration of motor and sensory neurons, proximal muscular atrophy, and endocrine abnormalities, such as gynecomastia and reduced fertility. We describe the development of a transgenic model of SBMA expressing a full-length human AR (hAR) cDNA carrying 65 (AR(65)) or 120 CAG repeats (AR(120)), with widespread expression driven by the cytomegalovirus promoter. Mice carrying the AR(120) transgene displayed behavioral and motor dysfunction, while mice carrying 65 CAG repeats showed a mild phenotype. Progressive muscle weakness and atrophy was observed in AR(120) mice and was associated with the loss of alpha-motor neurons in the spinal cord. There was no evidence of neurodegeneration in other brain structures. Motor dysfunction was observed in both male and female animals, showing that in SBMA the polyglutamine repeat expansion causes a dominant gain-of-function mutation in the AR. The male mice displayed a progressive reduction in sperm production consistent with testis defects reported in human patients. These mice represent the first model to reproduce the key features of SBMA, making them a useful resource for characterizing disease progression, and for testing therapeutic strategies for both polyglutamine and motor neuron diseases.     

Candida-specific cell-mediated immunity is demonstrable in mice with experimental vaginal candidiasis.

Women with recurrent vulvovaginal candidiasis often demonstrate a down-regulation of cell-mediated immunity (CMI) to Candida albicans detected by a lack of cutaneous delayed-type hypersensitivity (DTH) to Candida antigens. However, the role of systemic CMI as a host defense mechanism against recurrent vulvovaginal candidiasis is not well understood, in part because of the lack of a well-defined murine model of vaginal candidiasis. The present study was undertaken to determine: (i) whether soluble Candida culture filtrate antigens (CaCF) could be used to induce and detect Candida-specific CMI in mice and (ii) whether these antigens would be useful in detecting systemic CMI in mice given an experimental Candida vaginal infection. To this end, mice were immunized subcutaneously with CaCF in complete Freund's adjuvant, and within 7 days they developed Candida-specific DTH reactivity detected by footpad swelling (increase in footpad thickness, 0.36 mm) 24 h after footpad challenge with CaCF. Adoptive transfer studies showed that the DTH responsiveness was elicited by CD4+ DTH T cells. In mice given a vaginal inoculum of C. albicans blastoconidia (5 x 10(5)), footpad challenge with CaCF resulted in positive DTH responses (0.24 mm) as early as 1 week, responses similar to immunization in 2 to 3 weeks (0.33 mm), and sustained low levels of DTH reactivity (0.15 mm) through 10 weeks of vaginal infection. Vaginal lavage cultures revealed that peak vaginal Candida burden occurred 1 week post-vaginal inoculation (10(5) CFU) and declined 16-fold by week 10. These results provide evidence that Candida-specific systemic CMI is generated and can be detected longitudinally in mice with Candida vaginitis by a multiantigen preparation of Candida organisms which both initiates and detects Candida-specific CMI.     

H-Y antigen expression in patients with X-autosomal translocations and gonadal dysgenesis

Cells from three patients with early gonadal failure and a balanced reciprocal translocation involving the long arm of the X chromosome and an autosome were studied. Fibroblasts from a patient with a similar balanced reciprocal translocation but normal reproductive capabilities were also studied. Two of the four patients were found to have serologically detectable H-Y antigen on their cells. Since H-Y antigen has been found on the cells of other patients with X chromosome abnormalities but without a Y chromosome, it is thought that the X chromosome plays a role in the regulation of H-Y antigen expression. This study suggests that the long arm of the X chromosome may be involved but the location of a regulatory gene cannot be identified in these studies. These cases do not permit us to implicate H-Y antigen as a cause of gonadal dysgenesis and early gonadal failure in females who have structurally abnormal X chromosomes.     

Discrimination of human pathogenic subspecies of Francisella tularensis by using restriction fragment length polymorphism

We describe the use of two insertion sequence elements (ISFtu1 and ISFtu2) in Francisella tularensis to type strains by restriction fragment length polymorphism (RFLP). The RFLP profiles of 17 epidemiologically unrelated isolates were determined and compared. Our results showed that RFLP profiles can be used to assign F. tularensis strains into five main groups corresponding to strains of F. tularensis subsp. tularensis, F. tularensis strain ATCC 6223, strains of F. tularensis subsp. holarctica, strains of F. tularensis subsp. holarctica from Japan, and F. tularensis subsp. mediaasiatica. The results confirm the genetic identities of these subspecies and also support the suggestion that strains of F. tularensis subsp. holarctica from Japan should be considered members of a separate biovar. These findings should support future studies to determine the genetic differences between strains of F. tularensis at the whole-genome level.     

Cloning and expression of the major secreted cathepsin B-like protein from juvenile Fasciola hepatica and analysis of immunogenicity following liver fluke infection

The functions of the cathepsin B-like proteases in liver flukes are unknown and analysis has been hindered by a lack of protein for study, since the protein is produced in small amounts by juvenile flukes. To circumvent this, we isolated and characterized a cDNA encoding the major secreted cathepsin B from Fasciola hepatica. The predicted preproprotein is 339 amino acids in length, with the mature protease predicted to be 254 amino acids long, and shows significant similarity to parasite and mammalian cathepsin B. Only one of the two conserved histidine residues required for cathepsin B exopeptidase activity is predicted to be present. Recombinant preproprotein was produced in yeast, and it was shown that the recombinant proprotein can undergo a degree of self-processing in vitro to the mature form, which is active against gelatin and synthetic peptide substrates. The recombinant protein is antigenic in vaccinated rats, and antibodies to the protein are detected early after infection of rats and sheep with F. hepatica. The kinetics of the response to cathepsin B and cathepsin L after infection of sheep and rats confirm the temporal expression of these proteins during the life cycle of the parasite.     

Development of neural processes mediating rhyme judgments: Phonological and orthographic interactions

Development of neural processes underlying integration of phonological and orthographic information were assessed by measuring event-related brain potentials (ERPs), judgment accuracies and reaction times (RTs) in 20 children (9-10 years) and 20 adults performing visual rhyme judgments. Half the trials were phonologically and orthographically congruent across the prime-target pairs (e.g., thrown-own, cake-own), and half were incongruent (e.g., gown-own, cone-own). For both children and adults, behavioral performance was most affected when different phonological representations had to be encoded from similar orthographic representations (e.g., gown-own), and the amplitudes of the N350 reflected effects of both rhyme and phonological/orthographic congruency. Latencies of the N350 were shorter over the left hemisphere only in adults, and phonological/orthographic incongruence produced greater delays in children's processing. Therefore, it appears that neural systems mediating rhyming judgments develop early; however, adults exhibit increased efficiency for left-hemisphere processing and are less affected by interference from incongruent phonological and orthographic codes.     

Variance in practice emergency medical admission rates: can it be explained?

BACKGROUND: Emergency admission rates have been rising steadily in recent years, with the majority of the increase owing to emergency medical admissions. Possible causative factors include changing demography, incidence of disease, admission thresholds, multiple admissions, and appropriateness of admission. AIM: To investigate the impact of patient and practice factors on variance in general practices' emergency medical admissions rates. DESIGN OF STUDY: Multiple regression analysis relating emergency medical admission rates of general practices to patient and practice characteristics. SETTING: The study was conducted between 1996 and 1997 in the acute hospital trust serving the study area, Dundee, Scotland. METHOD: Scottish Morbidity Record 1 (SMR1) data, which contains details of all hospital consultant episodes, was used to calculate individual practices emergency medical admission rates. These rates were then standardised to an expected value of 100. Forward selection was used to find a suitable multiple regression model to predict each practice's emergency medical admission rate from practice and patient variables. RESULTS: Crude emergency medical admission rates for general practices showed a 1.8-fold variation between the top and bottom deciles. The deprivation status and age of patients explained 42% of the variance in admission rates (64% with the exclusion of one practice that had a poor fit to the model). After correcting for age and deprivation there was a 1.2-fold variation in general practices' emergency medical admission rates. CONCLUSION: The most important factors in explaining variance in general practices' emergency medical admission rates are socio-demographic, with age and deprivation explaining a large proportion of the variation. We found no evidence to support the contention that general practice factors were linked with admission rates.     

Factors associated with BMI, weight perceptions and trying to lose weight in African-American smokers

This study examined sociodemographic, behavioral and psychosocial factors associated with BMI, weight perceptions and trying to lose weight among African-American smokers (N=600, M=44.2 years, 70% female). Sixty-eight percent of the sample were overweight or obese (sample BMI M=28.0, SD=6.7). Three separate, simultaneous multivariable regression models were used to determine which factors were associated with BMI, weight perceptions and trying to lose weight. Poorer health, female gender and high-school education or higher were significantly associated with higher BMIs (p<0.05). Being female (OR=5.8, 95% CI=3.6-9.3) and having a higher BMI (OR=0.6, 95% CI=0.5-0.6) was associated with perception of overweight and smoking more cigarettes per day (OR=1.0, 95% CI=1.0-1.1), and perceiving oneself as overweight (OR=14.1, 95% CI=8.2-24.2) was associated with trying to lose weight. Participants somewhat underestimated their BMI in their weight perceptions. Those who perceived themselves as overweight were more likely to be trying to lose weight; therefore, increasing participant awareness of actual BMI status may lead to improved weight-control efforts in African-American smokers. Several expected associations with outcomes were not found, suggesting that BMI and weight constructs are not well-understood in this population.     

Use of the MGB Eclipse system and SmartCycler PCR for differentiation of Mycobacterium chelonae and M. abscessus

Although accurate in the identification of Mycobacterium species, partial 16S rRNA gene sequencing does not distinguish Mycobacterium chelonae from M. abscessus. Thus, we designed a SmartCycler PCR assay targeting the 16S-to-23S internal transcribed spacer (ITS) region with use of MGB Eclipse probes to distinguish each species. Comparison with PCR-restriction enzyme analysis of a 441-bp fragment of the hsp65 gene resulted in 100% correlation with 25 isolates of M. chelonae and 25 isolates of M. abscessus. ITS PCR performed on 90 consecutive isolates identified by partial 16S rRNA gene sequencing (26 isolates of the M. chelonae-M. abscessus complex and 64 remaining isolates, including Mycobacterium species, Nocardia species, and other aerobic actinomycetes) showed 100% specificity and sensitivity. The ITS PCR assay is accurate and specific, easy to perform, and a good supplemental test when using partial 16S rRNA gene sequencing to identify M. chelonae and M. abscessus.     

Intact perceptual and conceptual priming in temporal lobe epilepsy: neuroanatomical and methodological implications

Explicit memory appears to be supported by medical temporal lobe structures, whereas separate neocortical regions may mediate perceptual and conceptual implicit memory. Children and adults with temporal lobe epilepsy (TLE) and matched controls were administered experimental verbal memory tests. Performance on implicit tests--word identification and word generation--was contrasted with explicit recognition and recall. Encoding conditions emphasized either conceptual or perceptual aspects of study words and were crossed with presentation modality. The priming performance of participants with TLE did not differ from controls, but participants with TLE did show deficits on recognition and recall measures. Thus, intact left temporal cortex does not appear to be necessary for normal implicit memory performance, even when conceptual processing is emphasized at study or test.