TB PCR in the early diagnosis of tuberculous meningitis: evaluation of the Roche semi-automated COBAS Amplicor MTB test with reference to the manual Amplicor MTB PCR test

SETTING

Cecilia Makiwane Hospital, Mdantsane, Eastern Cape, Republic of South Africa.

OBJECTIVE

To assess the role of the semi-automated Roche COBAS AMPLICOR(TM)Mycobacterium tuberculosis PCR test in the diagnosis of tuberculous meningitis (TBM).

DESIGN

Eighty-three specimens of cerebrospinal fluid (CSF) were collected prospectively from 69 patients with suspected TBM. The COBAS AMPLICOR TB PCR test was compared with the manual AMPLICOR(TM)TB PCR test, clinical and cerebrospinal fluid (CSF) findings, direct ZN smear and radiometric TB culture.

RESULTS

CSF from 7/40 (17.5%) patients treated for TBM were positive by TB COBAS AMPLICOR(TM). The sensitivity of the test was not significantly different (p=0.375) from the manual TB AMPLICOR(TM)PCR test. The comparative sensitivities of the TB COBAS AMPLICOR(TM)PCR and the manual AMPLICOR PCR for detecting cases of definite and probable TBM from CSF collected within 9 days of commencing antituberculosis treatment were 40% and 60% respectively. All 29 patients not treated for TBM were negative by COBAS AMPLICOR(TM), giving a specificity of 100%.

CONCLUSION

The COBAS AMPLICOR(TM)TB PCR test is a rapid and highly specific diagnostic test for TBM. However, there was a non-significant trend favouring slightly greater sensitivity using the manual AMPLICOR(TM)TB PCR test.

A family genetic study of autism associated with profound mental retardation

We sought to determine if the family loading for either the broader autism phenotype or for cognitive impairment differed according to whether or not autism was accompanied by severe mental retardation. The sample comprised 47 probands with autism meeting ICD-10 criteria, as assessed by the Autism Diagnostic Interview and the Autism Diagnostic Observation Schedule. Family history interview and findings were compared with those for the higher IQ autism and Down syndrome samples in the Bolton et al. (1994) study. The familial loading for autism and for the broader phenotype was closely comparable to that in the study of higher IQ autism, and different from that for Down syndrome. The family loading for scholastic achievement difficulties was slightly, but significantly, higher when autism was accompanied by severe retardation.

Re-entrant cardiac arrhythmias in computational models of long QT myocardium

The long QT syndrome (LQTS) is an inherited disorder in which repolarization of cardiac ventricular cells is prolonged. Patients with the LQTS are at an increased risk of ventricular cardiac arrhythmias. Two phenotypes of the inherited LQTS are caused by defects in K(+)channels (LQT1 and LQT2) and one by defects in Na(+)channels (LQT3). Patients with LQT1 are more likely to have self-terminating arrhythmias than those with LQT3. The aim of this computational study was to propose an explanation for this finding by comparing the vulnerability of normal and LQT tissue to re-entry, and estimating the likelihood of self-termination by motion of re-entrant waves to an inexcitable boundary in simulated LQT1, LQT2 and LQT3 tissue. We modified a model of mammalian cardiac cells to simulate LQT1 by reducing maximal I(K(s))conductance, LQT2 by reducing maximal I(K(r))conductance, and LQT3 by preventing complete inactivation of I(Na)channels. Each simulated phenotype was incorporated into a computational model of action potential propagation in one- and two-dimensional homogeneous tissue. Simulated LQT tissue was no more vulnerable to re-entry than simulated normal tissue, but the motion of re-entrant waves in simulated LQT1 tissue was between 2 and 5 times greater than the motion of re-entrant waves in simulated LQT2 and LQT3 tissue. These findings suggest that LQT arrhythmias do not result from increased vulnerability to re-entry, and that re-entry once initiated is more likely to self-terminate by moving to an inexcitable tissue boundary in LQT1 than in LQT2 and LQT3. This finding is consistent with clinical observations.

Nontuberculous mycobacterial disease following hot tub exposure

Nontuberculous mycobacteria (NTM) have been recognized as an important cause of disease in immunocompromised hosts. Pulmonary disease caused by NTM is increasingly recognized in previously healthy persons. Investigation of pulmonary disease affecting a family of five identified an indoor hot tub as the source of NTM-related disease.

Genetic clues to the biological basis of autism

Autism, the prototypical pervasive developmental disorder, is characterized by impaired communication and social interaction, and by repetitive interests and behaviours. The core disorder probably affects around 5:10 000 individuals, of whom some three-quarters are male. Onset is in the first three years of life, and the disorder is associated with lifelong disabilities. Because of the clear evidence that idiopathic autism has a strong genetic basis, many groups are undertaking whole genome screens to identify susceptibility loci. We review the first results, and briefly consider the implications of molecular genetic findings for future research, diagnosis and management.

Ornithine decarboxylase of Stagonospora (Septoria) nodorum is required for virulence toward wheat

A knockout strain of Stagonospora (Septoria) nodorum lacking the single ornithine decarboxylase (ODC) allele has been created by targeted gene replacement. A central region of the S. nodorum ODC gene was isolated by polymerase chain reaction using degenerate oligonucleotides and used to probe a lambda genomic library. The gene was sequenced and the encoded ODC protein sequence was shown to be similar to those from other fungi. The functionality of the S. nodorum ODC was confirmed by complementation of an Aspergillus nidulans mutant (puA) strain devoid of ODC activity, restoring growth in the absence of exogenous polyamines. Sporulation of the transformants was reduced suggesting abberant regulation of the S. nodorum gene in A. nidulans. Transformation-mediated gene replacement was used to create strains which were auxotrophic for putrescine and lack ODC coding sequences. Pathogenicity studies on these mutants showed that they are greatly reduced in virulence compared with non-disrupted transformants. This confirms that the strains carrying an ODC disruption cannot obtain sufficient polyamines from the host plant for normal growth and, thus, that fungal ODC may be a suitable target for chemical intervention.

Variable expression of the autism broader phenotype: findings from extended pedigrees

Factors influencing the rate, form, and severity of phenotypic expression among relatives of autistic probands are examined. Family history data on 3095 first- and second-degree relatives and cousins from 149 families with a child with autism and 36 families with a child with Down syndrome are studied. The results provide further evidence of an increased risk among autism relatives for the broadly defined autism phenotype. Of proband characteristics, severity of autism and obstetric optimality were confirmed as being related to familial loading for probands with speech. There was little variation in loading among probands lacking speech. The type of phenotypic profile reported in relatives appeared little influenced by characteristics of the relative or the proband, except for variation by degree of relative, parental status of relative, and perhaps proband's birth optimality score. Phenotypic rates among parents suggested reduced fitness for the severest and more communication-related forms of expression but not for the more mild and social forms of expression. Patterns of expression within the families did not support a simple X-linked nor an imprinted X-linked mode of inheritance. The basis for sex differences in rates of expression is discussed.

Autism: recent molecular genetic advances

Autism (MIM 209850) is a severe neuropsychiatric disorder of unknown aetiology with profound consequences for patients and their families. Strong evidence from twin and family studies indicates the importance of genetic factors in the development of idiopathic autism, although it is clear that these influences are complex. This review focuses on recent molecular investigations to identify susceptibility loci implicated in autistic disorder.

Immunogenicity of porcine transmissible gastroenteritis virus spike protein expressed in plants

Transgenic plants expressing recombinant proteins from pathogenic microorganisms provide an inexpensive edible vaccine for induction of local immunity. Three transgenic plant lines were generated expressing the spike (S) protein of transmissible gastroenteritis virus (TGEV), a protein crucial for establishing mucosal immunity. All three of them were driven by a strong plant promoter. One construct contained the 3.7 kb 5' end of the native S gene sequence. In the second construct part of the S gene, from nucleotide 49 to 1785, was modified for optimal plant recognition and was fused to a plant signal peptide coding sequence. The third construct contained the D epitope-coding region of the S gene, from nucleotide 1201 to 1591, which was fused to the alfalfa beta-amylase gene. The S gene products were detected by enzyme-linked immunosorbent assay (ELISA) and Western blotting. Antigens from all three transgenic plant lines induced TGEV-specific immune responses in pigs as determined by virus neutralization and ELISA, and the resultant antibody titers for all three constructs were similar.

A group of expressed cDNA sequences from the wheat fungal leaf blotch pathogen, Mycosphaerella graminicola (Septoria tritici)

A group of expressed sequence tags (ESTs) from the wheat fungal pathogen Mycosphaerella graminicola utilizing ammonium as a nitrogen source has been analyzed. Single pass sequences of complementary DNAs from 986 clones were determined. Contig analysis and sequence comparisons allowed 704 unique ESTs (unigenes) to be identified, of which 148 appeared as multiple copies. Searches of the nrdb95 protein database at EMBL using the BLAST2x algorithm revealed 407 (57.8%) sequences that generated high to moderate high scoring pairs with proteins of known and unknown function. The rest of the sequences (297) showed either weak or no similarities to database entries. Among the unigenes with assigned function, 26.7% were involved in primary metabolism and 17.9% were associated with protein and RNA metabolism. Fewer clones were ascribed roles in signal transduction (4.9%), transport and secretion (6.1%), cell structure (3.1%), and cell division (3.6%). Approximately 18.1% of the identities found were to hypothetical or unknown proteins mainly from the yeasts Saccharomyces cerevisiae and Schizosaccaromyces pombe. Comparison of the 297 sequences with no clear function to other fungal ESTs in the public domain revealed 12 sequences that had high to moderate similarity to Neurospora crassa, Emericella (Aspergillus) nidulans, or Magnaporthe grisea sequences.

Association analysis of the vitamin D receptor gene, the type I collagen gene COL1A1, and the estrogen receptor gene in idiopathic osteoarthritis

OBJECTIVE

Evidence has accumulated supporting a role for genes in the etiology of osteoarthritis (OA). Several candidates have been targeted as potential susceptibility loci including genes that are involved in the regulation of bone density. Genetic association analysis has suggested a role for the vitamin D receptor gene (VDR) and the estrogen receptor gene (ER) in susceptibility. Such findings must be tested in additional independent cohorts. We tested for association of these 2 genes, plus a third gene implicated in bone density, COL1A1, with idiopathic OA.

METHODS

A case-control cohort of 371 affected probands and 369 unaffected spouses was used. Association was tested using 4 intragenic single nucleotide polymorphisms (SNP), one each for the VDR and COL1A1 genes, and 2 for the ER gene. The VDR and ER SNP are the same SNP that have been associated with OA. All 4 SNP affect restriction enzyme sites and were genotyped using polymerase chain reaction and enzyme digestion. Allele and genotype distributions for each SNP were compared between cases and controls and analyzed using Fisher's exact test.

RESULTS

There was no evidence of association of the VDR or the ER gene SNP to OA. There was weak evidence of association of the COL1A1 SNP in female cases (p = 0.017), reflected by a difference in the distribution of genotypes at this SNP between female cases and controls (p = 0.027). However, when corrected for multiple testing, these results were not significant.

CONCLUSION

If the VDR, ER, or COL1A1 genes do encode predisposition to OA then the 4 SNP tested are not associated with major susceptibility alleles at these 3 loci.

Properties of the adenovirus type 40 E1B promoter that contribute to its low transcriptional activity

The adenovirus type 5 (Ad5) E1B promoter contains two elements essential for maximal activity, a TATA box and a GC box. The enteric adenovirus type 40 (Ad40) E1B promoter has a TATA box sequence identical to that of Ad5 and a GC box that fits the Sp1 binding site consensus. Nevertheless, Ad40 E1B RNA synthesis is severely impaired in HeLa cells, attributable in part at least to the weak transactivating activity of Ad40 E1A. However, the responsiveness of Ad40 early promoters to E1A transactivation has not been directly demonstrated. Using a transient expression assay with a chloramphenicol acetyl transferase (CAT) reporter gene, the Ad40 E1B promoter was very poorly transactivated by E1A of both Ad40 and Ad5 and showed only a limited response to the promiscuous varicella zoster virus transactivator p140. Construction of Ad5 recombinant viruses expressing the CAT gene under the control of the Ad5 or Ad40 E1B promoter allowed detection and measurement of expression from the Ad40 E1B promoter in a well-defined background and showed that overall activity is some 100-fold lower than for the Ad5 E1B promoter. Deletion analysis revealed that sequences upstream of the Sp1 binding site down-modulated Ad40 E1B promoter responsiveness, and two protein binding sites, identified by DNase footprinting and gel retardation assay, may be implicated in this effect. Gel shift analysis also showed that the Ad40 Sp1 binding site had a reduced affinity for Sp1 protein, relative to the Ad5 site, and that the context as well as the core sequence had an influence on Sp1 recognition.

Autism screening questionnaire: diagnostic validity

BACKGROUND

Good interview and diagnostic measures for autism and other pervasive developmental disorders (PDDs) are available but there is a lack of a good screening questionnaire.

AIMS

To develop and test a screening questionnaire based on items in the best available diagnostic interview--the Autism Diagnostic Interview--Revised (ADI-R).

METHOD

A 40-item scale, the Autism Screening Questionnaire (ASQ), was developed and tested on a sample of 160 individuals with PDD and 40 with non-PDD diagnoses.

RESULTS

The ASQ has good discriminative validity with respect to the separation of PDD from non-PDD diagnoses at all IQ levels, with a cut-off of 15 proving most effective. The differentiation between autism and other varieties of PDD was weaker.

CONCLUSIONS

The ASQ is an effective screening questionnaire for PDD.

Depressive symptoms in schizophrenia

OBJECTIVE

The authors assessed the presence and severity of depressive symptoms, as well as their associations with other clinical measures, in a group of mid- to late-life patients with schizophrenia who were not in a major depressive episode or diagnosed with schizoaffective disorder.

METHOD

Sixty outpatients with schizophrenia between the ages of 45 and 79 years and 60 normal comparison subjects without major neuropsychiatric disorders, proportionally matched for age and gender, were studied. Depressive symptoms were rated primarily with the Hamilton Depression Rating Scale. Standardized instruments were also used to measure global psychopathology, positive and negative symptoms, abnormalities of movement, and global cognitive status.

RESULTS

Depressive symptoms were more frequent and more severe in schizophrenic patients than in normal comparison subjects; 20% of the women with schizophrenia had a Hamilton depression scale score of 17 or more. Severity of depressive symptoms correlated with that of positive symptoms but not with age, gender, negative symptoms, extrapyramidal symptoms, or neuroleptic dose.

CONCLUSIONS

Depressive symptoms are common in older patients with schizophrenia. They may be an independent, core component of the disorder or, alternatively, may be a by-product of severe psychotic symptoms.

Serotonin transporter (5-HTT) and gamma-aminobutyric acid receptor subunit beta3 (GABRB3) gene polymorphisms are not associated with autism in the IMGSA families. The International Molecular Genetic Study of Autism Consortium

Previous studies have suggested that the serotonin transporter (5-HTT) gene and the gamma-aminobutyric acid receptor subunit beta3 (GABRB3) gene, or other genes in the 15q11-q13 region, are possibly involved in susceptibility to autism. To test this hypothesis we performed an association study on the collection of families from the International Molecular Genetic Study of Autism (IMGSA) Consortium, using the transmission disequilibrium test. Two polymorphisms in the 5-HTT gene (a functional insertion-deletion polymorphism in the promoter and a variable number tandem repeat in the second intron) were examined in 90 families comprising 174 affected individuals. Furthermore, seven microsatellite markers spanning the 15q11-q13 region were studied in 94 families with 182 affected individuals. No significant evidence of association or linkage was found at any of the markers tested, indicating that the 5-HTT and the GABRB3 genes are unlikely to play a major role in the aetiology of autism in our family data set.

Semiquantitative polymerase chain reaction enzyme immunoassay for the diagnosis of pertussis

The two most commonly used targets for diagnosis of pertussis by the polymerase chain reaction have been the pertussis toxin promoter and the repeated insertion sequence IS481. A comparative assessment of these primers was performed on routinely collected nasopharyngeal swabs, stored at -20 C, using novel semiquantitative enzyme immunoassays. Both sets of primers behaved similarly with bacterial suspensions, and the 17 culture-positive nasopharyngeal swabs were also positive with the pertussis toxin promoter primers, with one exception, which had been subject to prolonged storage. Significantly more of the 69 culture-negative swabs were positive with the pertussis toxin promoter primers (n = 36) than with the IS481 primers (n = 18). To determine the effect of inhibitors, a comparative assessment of three primer pairs against human DNA (beta-globin and glyceraldehyde-3-phosphate dehydrogenase) was also performed.

High throughput detection of retrovirus-associated reverse transcriptase using an improved fluorescent product enhanced reverse transcriptase assay and its comparison to conventional detection methods

The development and application of a novel, sensitive TaqMan fluorescent probe-based product enhanced RT test (F-PERT) for the detection of retrovirus are described. The assay allows discrimination between the amplification signals generated by genuine positive signals that result from retroviral RT activity and the RT-like activity from DNA polymerases. The RT-like activity from DNA polymerases was suppressed by the addition of activated calf-thymus DNA with no reduction in the RT activity. A linear relationship between threshold cycle (C(T)) and the number of virus particles was demonstrated, allowing quantification of retroviruses in unknown samples. The F-PERT assay was able to detect a wide range of retroviral RT activities, including that from porcine endogenous retrovirus (PoERV), murine leukaemia virus (MLV), simian foamy virus (SFV), simian immunodeficiency virus (SIVmac) and squirrel monkey retrovirus (SMRV). The detection limit of SMRV, MLV and PoERV was approximately 100 virion particles and the test was able to detect at least 10(2) molecules of purified RT enzyme. RT activity was not detected in cellular lysates and supernatants from MRC-5, BT, VERO, or Raji cells, whereas RT activity was detected in C1271, Mus dunni, K-Balb, BHK-21, CHO-K1, SP2/0-Ag14 and NSO cell supernatants. RT activity was also detected in the Spodoptera cell line Sf9.

A comparative evaluation of a fibromyalgia rehabilitation program

OBJECTIVE

To compare an evidence-based clinical fibromyalgia program, referred to as Fibro-Fit, with results of controlled clinical trials.

METHODS

An interdisciplinary group education and exercise program with 36 sessions over 12 weeks was used. Demographic, clinical, and outcome variables were collected on 149 participants, of whom 71% completed the program. Outcomes included measures of self-efficacy, pain, physical fitness, function, and coping skills.

RESULTS

Results of the prospective before-after evaluation showed statistically significant (P < 0.005) improvements in all outcomes except for grip strength. These results were comparable with controlled clinical trials found in the literature. Data suggest that smoking, fibromyalgia support groups, and medications may be important modifiable factors.

CONCLUSIONS

Results suggest that Fibro-Fit was effective in improving physical impairments and function. Further investigation is required to refine the effective components of these programs and determine how modifiable factors can be used to improve outcomes.

Lower incidence of tardive dyskinesia with risperidone compared with haloperidol in older patients

OBJECTIVE

To compare the 9-month cumulative incidence of tardive dyskinesia (TD) with risperidone to that with haloperidol in older patients.

DESIGN

A prospective longitudinal study.

SETTING

An outpatient psychiatric clinic.

PARTICIPANTS

Subjects were middle-aged and older (mean age 66 years) patients with schizophrenia, dementia, mood disorders, or other conditions with psychotic symptoms or severe behavioral disturbances. Sixty-one patients on risperidone were matched with 61 patients from a larger sample of haloperidol-treated patients in regard to age, diagnosis, and length of pre-enrollment neuroleptic intake to create clinically comparable groups. The median daily dose of each medication was 1.0 mg.

MEASUREMENTS

Abnormal Involuntary Movement Scale, modified Simpson-Angus' scale for extrapyramidal symptoms, Brief Psychiatric Rating Scale, and Mini-Mental State Examination were administered at baseline, 1 month, and 3, 6, and 9 months. The diagnosis of TD was based on specific research criteria. The raters were blind to the patient's medication status.

RESULTS

Life table analysis revealed that patients treated with haloperidol were significantly more likely to develop TD than patients treated with risperidone (P < .05, Peto-Prentice).

CONCLUSIONS

The atypical antipsychotic risperidone is significantly less likely to result in TD than the conventional neuroleptic haloperidol in a high-risk group of older patients, at least over a 9-month period.