Preventing tuberculosis in the foreign-born population of Canada: a mathematical modelling study

BACKGROUND

Foreign-born persons in Canada contribute 67% of all tuberculosis (TB) cases annually, but represent only 21% of the total population. Molecular epidemiological studies suggest that most foreign-born TB cases result from the reactivation of latent tuberculous infection (LTBI) acquired before immigration.

OBJECTIVE

To estimate the effect on incidence of a prevention strategy that would screen selected immigrants at arrival for LTBI and offer preventive treatment to those who test positive.

DESIGN

A deterministic model was developed to quantify the incidence of active TB in immigrants to Canada and validated with national immigration and TB case data.

RESULTS

Model simulations suggested that it would be optimal to screen and treat LTBI in new immigrants from countries of birth with an estimated TB incidence rate in excess of 50 per 100 000 person-years. If this strategy had been implemented in 1986, the national TB incidence rate would have fallen by 18.5%, from 5.4 to 4.4 cases per 100 000 population by 2002.

CONCLUSION

This study suggests that screening and treating LTBI in foreign-born persons from high TB incidence countries is the most effective strategy in terms of total persons screened and treated and percentage reduction in national incidence.

Sustained response to deep brain stimulation in LRRK2 parkinsonism with the Y1699C mutation

Although effective deep brain stimulation of the subthalamic nucleus (STN-DBS) is reported in G2019S leucine-rich repeat kinase 2 (LRRK2) parkinsonism, response to surgery in other LRRK2 mutations has not been previously reported. We present an affected individual from the Lincolnshire pedigree (Y1699C), on whom bilateral STN-DBS was performed to control severe motor fluctuations and dyskinesias. He showed a marked improvement in Unified Parkinson's Disease Rating Scale (UPDRS) Part III scores in the "on" and "off" states, sustained for more than three years. Bilateral STN-DBS in LRRK2-parkinsonism with the Y1699C mutation can be as effective as in sporadic PD.

The cardioprotectant 3',4'-dihydroxyflavonol inhibits opening of the mitochondrial permeability transition pore after myocardial ischemia and reperfusion in rats

The study aimed to determine the effect of 3',4'-dihydroxyflavonol (DiOHF) on mitochondrial function, in particular opening of the mitochondrial permeability transition pore (mPTP), respiratory function and reactive oxygen species (ROS) production, in isolated cardiac mitochondria after coronary artery occlusion and reperfusion in vivo. Opening of the mPTP, oxygen consumption and ROS production (assessed by measurement of H2O2) was determined in mitochondria isolated from normal hearts or from the ischemic zone of rat hearts subjected to 30min coronary artery occlusion and 15min reperfusion. Treatment of sham rats with DiOHF (10mgkg(-1) iv) significantly increased the concentration of Ca(2+) required to stimulate mPTP opening. This was accompanied by increased state 3 oxygen consumption and decreased H2O2 release. Ischemia and reperfusion (IR) significantly decreased the concentration of Ca(2+) required to stimulate mPTP opening, decreased state 3 oxygen consumption and increased H2O2 release, when pyruvate plus malate was provided as a substrate. Treatment with DiOHF prevented IR-induced changes in mPTP opening, state 3 oxygen consumption and H2O2 release so that there was no difference compared to sham. In isolated cardiac mitochondria from normal rats DiOHF had no effect on mPTP opening or on state 3 respiration but caused a small increase in state 4 respiration and decreased the respiratory control ratio. DiOHF, administered during ischemia just before reperfusion, inhibits mPTP opening and preserves mitochondrial function through a mechanism likely to be independent of its antioxidant activity or any direct effect on the mPTP.

Transcriptome profiling of UPF3B/NMD-deficient lymphoblastoid cells from patients with various forms of intellectual disability

The nonsense-mediated mRNA decay (NMD) pathway was originally discovered by virtue of its ability to rapidly degrade aberrant mRNAs with premature termination codons. More recently, it was shown that NMD also directly regulates subsets of normal transcripts, suggesting that NMD has roles in normal biological processes. Indeed, several NMD factors have been shown to regulate neurological events (for example, neurogenesis and synaptic plasticity) in numerous vertebrate species. In man, mutations in the NMD factor gene UPF3B, which disrupts a branch of the NMD pathway, cause various forms of intellectual disability (ID). Using Epstein Barr virus-immortalized B cells, also known as lymphoblastoid cell lines (LCLs), from ID patients that have loss-of-function mutations in UPF3B, we investigated the genome-wide consequences of compromised NMD and the role of NMD in neuronal development and function. We found that ~5% of the human transcriptome is impacted in UPF3B patients. The UPF3B paralog, UPF3A, is stabilized in all UPF3B patients, and partially compensates for the loss of UPF3B function. Interestingly, UPF3A protein, but not mRNA, was stabilised in a quantitative manner that inversely correlated with the severity of patients' phenotype. This suggested that the ability to stabilize the UPF3A protein is a crucial modifier of the neurological symptoms due to loss of UPF3B. We also identified ARHGAP24, which encodes a GTPase-activating protein, as a canonical target of NMD, and we provide evidence that deregulation of this gene inhibits axon and dendrite outgrowth and branching. Our results demonstrate that the UPF3B-dependent NMD pathway is a major regulator of the transcriptome and that its targets have important roles in neuronal cells.

A population-based study of tuberculosis epidemiology and innovative service delivery in Canada

OBJECTIVE

To compare and interpret tuberculosis (TB) incidence rates in a Canadian population across two decennials (1989-1998 and 1999-2008) as a benchmark for World Health Organization targets and the long-term goal of TB elimination. The population under study was served by two urban clinics in the first decennial and two urban and one provincial clinic in the second.

METHODS

TB rates among Status Indians, Canadian-born 'others' and the foreign-born were estimated using provincial and national databases. Program performance was measured in on-reserve Status Indians in each decennial.

RESULTS

In each decennial, the incidence rate in Status Indians and the foreign-born was greater than that in the Canadian-born 'others'; respectively 27.7 and 33.0 times in Status Indians, and 8.0 and 20.9 times in the foreign-born. Between decennials, the rate fell by 56% in Status Indians, 58% in Canadian-born 'others', and 18% in the foreign-born. On-reserve Status Indians had higher rates than off-reserve Status Indians, and the three-clinic model out-performed the two-clinic model among those on-reserve. Rates in the foreign-born varied by World Bank region, and were highest among those from Africa and Asia.

CONCLUSION

Status Indians and the foreign-born are at increased risk of TB in Canada. Significant progress towards TB elimination has been made in Status Indians but not in the foreign-born.

Common functional polymorphisms of DISC1 and cortical maturation in typically developing children and adolescents

Disrupted-in-schizophrenia-1 (DISC1), contains two common non-synonymous single-nucleotide polymorphisms (SNPs)--Leu607Phe and Ser704Cys--that modulate (i) facets of DISC1 molecular functioning important for cortical development, (ii) fronto-temporal cortical anatomy in adults and (iii) risk for diverse psychiatric phenotypes that often emerge during childhood and adolescence, and are associated with altered fronto-temporal cortical development. It remains unknown, however, if Leu607Phe and Ser704Cys influence cortical maturation before adulthood, and whether each SNP shows unique or overlapping effects. Therefore, we related genotype at Leu607Phe and Ser704Cys to cortical thickness (CT) in 255 typically developing individuals aged 9-22 years on whom 598 magnetic resonance imaging brain scans had been acquired longitudinally. Rate of cortical thinning varied with DISC1 genotype. Specifically, the rate of cortical thinning was attenuated in Phe-carrier compared with Leu-homozygous groups (in bilateral superior frontal and left angular gyri) and accelerated in Ser-homozygous compared with Cys-carrier groups (in left anterior cingulate and temporal cortices). Both SNPs additively predicted fixed differences in right lateral temporal CT, which were maximal between Phe-carrier/Ser-homozygous (thinnest) vs Leu-homozygous/Cys-carrier (thickest) groups. Leu607Phe and Ser704Cys genotype interacted to predict the rate of cortical thinning in right orbitofrontal, middle temporal and superior parietal cortices, wherein a significantly reduced rate of CT loss was observed in Phe-carrier/Cys-carrier participants only. Our findings argue for further examination of Leu607Phe and Ser704Cys interactions at a molecular level, and suggest that these SNPs might operate (in concert with other genetic and environmental factors) to shape risk for diverse phenotypes by impacting on the early maturation of fronto-temporal cortices.

Piecing the puzzle together: foreign-born tuberculosis in an immigrant-receiving country

In major immigrant-receiving countries, annual foreign-born tuberculosis (TB) case counts and rates are relatively constant. Why this is so, and who might be a high-yield target for screening for latent TB infection, remain open questions. Foreign-born TB in Canada during 1986-2002 was retrospectively examined using national TB and immigration data as well as census data. Case counts and rates were analysed in relation to demographics, immigration period and time since arrival. Pre-1986 immigrants (n=3,860,853) and 1986-2002 immigrants (n=3,463,283) contributed 8,662 and 9,613 TB cases, respectively. Immigrants arriving ≤ 5 yrs ago and those arriving >10 yrs ago contributed almost equally to the annual foreign-born TB case count despite a 3.5-fold difference in in-country person-yrs. Remarkably stable and relatively low TB incidence was observed among immigrants >10 yrs post-arrival. Conversely, TB incidence within 5 yrs of arrival was dynamic, demonstrating a strong inverse association with time since arrival and higher sensitivity to changes in immigration level than shifts toward higher incidence source countries. Relative constancy in foreign-born TB incidence is explained by a complex convergence of several factors. Immigrants born in high-incidence countries who arrived ≤ 2 yrs ago and were aged 15-34 yrs upon arrival constitute high-yield targets for preventive therapy.

Impact of pharmacotherapy on the incidence of transurethral prostatectomy for benign prostatic hyperplasia and the implications for surgical training

Medical therapy has become first line treatment for Benign Prostatic Hypertrophy (BPH) and in many cases TURP may no longer be required. Proof and quantification of this evolution in practice has been somewhat elusive and provided the principle impetus for this study. This is a retrospective study of BPH management in Republic of Ireland from 1995 to 2008. National treatment databases were sourced for numbers undergoing TURP and pharmacotherapy prescribing data was obtained from individual pharmaceutical companies. A total of 28,240 TURP's were performed nationally between 1995 and 2008. TURP's performed annually, decreased by 1,494 (51%), alpha-blocker prescriptions increased from 8,710 to 302,159 units and the number of urology trainees increased by 10 (60%). Clear association between decreases in TURP's and increases in pharmacotherapy for BPH is demonstrated. Implications on training likely exist and will require proper evaluation in order to maintain future standards in this surgical practice.

Factors associated with treatment adherence in a randomised trial of latent tuberculosis infection treatment

SETTING

Randomised controlled trial of latent tuberculosis infection (LTBI) treatment in 10 clinics in Canada, Saudi Arabia and Brazil.

OBJECTIVE

To identify early predictors of LTBI treatment adherence, including pre-treatment characteristics.

DESIGN

Patients randomised to 4 months of rifampicin (RMP; n = 420) or 9 months of isoniazid (n = 427) were monitored for adherence using an electronic device. Outcomes were 1) treatment completion, defined as intake of >or=80% of the prescribed doses, and further categorised as completed within the allotted time or not; and 2) treatment regularity, measured by the time interval between doses. Relative risk (RR) and adjusted odds ratios (aOR) of patients' pre-treatment characteristics and adherence at first follow-up visit were calculated.

RESULTS

Completion of treatment was higher with RMP (aOR 4.3, 95%CI 2.7-6.8). Early predictors (first follow-up visit) of non-adherence were late first visit attendance (RR for completion in time 0.9, 95%CI 0.8-0.98), >20% of missed doses (RR 0.4, 95%CI 0.3-0.6) and greater variation of hours between doses (0.209 vs. 0.131, P < 0.001). Serious adverse events were not associated with irregularity of treatment.

CONCLUSION

The shorter RMP regimen was associated with better adherence. Patients with poor adherence could be identified at the first follow-up visit from their punctuality in follow-up, missed doses and variability of pill-taking.

Morphological adaptations of yak (Bos grunniens) tongue to the foraging environment of the Qinghai-Tibetan Plateau

Using light and scanning electron microscopy, the morphological adaptations of the yak (Bos grunniens) tongue to its foraging environment in the Qinghai-Tibetan Plateau were studied. The tongue of the yak was compared with that of cattle (Bos taurus). Compared with cattle, yak tongues are on average 4 cm shorter (P < 0.001), and yak consume forages using the labia oris, rather than by extending the tongue into the harsh environment. The lingual prominence of yak is greater (P < 0.001) and more developed than in cattle. The conical papillae on the prominence surface of yak are slightly larger (diameter: P = 0.068 and height: P = 0.761) and more numerous (P < 0.001) than in cattle. The lenticular papillae on the prominence surface of yak are larger (diameter: P = 0.002 and height: P = 0.115) and more numerous (P = 0.007) than in cattle. Such characteristics may improve the digestibility of forage by the grinding of food between the tongue and the upper palate. Filiform, conical, lenticular, fungiform, and vallate papillae were observed on the dorsal surface of the tongues studied; no foliate papillae were observed. The papillae were covered by keratinized epithelium, which was thicker (P < 0.001) in the yak than in cattle. It is suggested that the development of characteristic filiform papillae, and more numerous lingual gland ducts and mucus-secreting pores in the lenticular, fungiform and vallate papillae, fungiform papillae, probably having mechanical functions, are all morphological adaptations by yak to diets with greater fiber and DM content as provided by the plants within the Qinghai-Tibetan Plateau environment. On average, yak has 26 vallate papillae and cattle have 28. In the vallate papillae of the yak, the taste buds are arranged in a monolayer within the epithelium, whereas they are multilayered (2 to 4) in those papillae in cattle. The number of taste buds in each vallate papillae was less (P < 0.001) in the yak than in cattle. Therefore, the gustatory function of the yak was weaker than in cattle. Yaks graze throughout the year on diverse natural grasslands and have evolved morphological characteristics enabling them to consume a wide variety of plant species, thereby better adapting them to the typically harsh characteristics of their pastures.

Fluoroquinolone resistance in renal isolates of Mycobacterium tuberculosis

SETTING

Alberta, Canada, 1990-2003.

OBJECTIVE

Monotherapy of active tuberculosis (TB) promotes drug resistance. Given the common practice of empiric fluoroquinolone (FQ) therapy for urinary tract infections (UTI) and frequent delayed diagnosis of renal TB, we assessed urine Mycobacterium tuberculosis isolates for FQ resistance.

DESIGN

Retrospective study. Urine M. tuberculosis isolates underwent FQ susceptibility testing. Records were reviewed for evidence of FQ exposure and diagnostic delay.

RESULTS

Among 78 culture-positive renal TB patients between 1990 and 2003, initial isolates of M. tuberculosis were available from 74 (94.9%). Three (4.1%) were FQ-resistant. Previous FQ use was confirmed in nine cases (12.2%). FQ-exposed isolates were more likely than non-exposed isolates to be FQ-resistant (2/9, 22.2% vs. 1/65, 1.5%, P = 0.037). Among 41 cases (55.4%) with signs or symptoms of UTI, eight (19.5%) had previous FQ exposure, of which seven (87.5%) had delayed diagnosis. Only 15/33 (45.5%) UTI symptomatic cases without prior FQ exposure had delayed diagnosis (P = 0.050). In 2/8 (25%) UTI symptomatic cases with prior FQ exposure, the M. tuberculosis isolate was FQ-resistant.

CONCLUSION

FQ monotherapy of unsuspected renal TB may delay diagnosis and lead to FQ resistance.

Bronchial anthracofibrosis and tuberculosis in immigrants to Canada from the Indian subcontinent

BACKGROUND

Bronchial anthracofibrosis is a condition of proximal airway narrowing or obliteration and hyperpigmentation in persons with or without a history of occupational dust exposure. It is a bronchoscopic finding that is not uncommonly associated with pulmonary tuberculosis (PTB) in residents of South Korea, Iran and India. It is largely unrecognized in the Western world.

METHODS

We report the frequency of anthracofibrosis in foreign-born PTB patients who underwent bronchoscopy in two cities of Canada. We describe the composition of the pigment in the lungs of patients and speculate on the pathogenesis of anthracofibrosis-associated PTB.

RESULTS

Anthracofibrosis was present in 10/60 (16.7%) foreign-born patients who underwent bronchoscopy and had PTB between 2002 and 2006. Compared to patients from other Asian countries, patients from the Indian subcontinent were more likely to have anthracofibrosis (9/18, 50.0% vs. 1/26, 3.7%, P < 0.001). Carbonaceous particles, silica and silicates predominated in tissue specimens. Proximal airway narrowing appeared to be secondary to mixed dust- and smoke-related anthracofibrosis, PTB, or both.

CONCLUSIONS

Anthracofibrosis is not uncommon in immigrants to Canada from the Indian subcontinent with PTB. PTB may be a responsible or complicating condition in patients with anthracofibrosis.

Clinical spectrum of SIX3-associated mutations in holoprosencephaly: correlation between genotype, phenotype and function

BACKGROUND

Holoprosencephaly (HPE) is the most common structural malformation of the human forebrain. There are several important HPE mutational target genes, including the transcription factor SIX3, which encodes an early regulator of Shh, Wnt, Bmp and Nodal signalling expressed in the developing forebrain and eyes of all vertebrates.

OBJECTIVE

To characterise genetic and clinical findings in patients with SIX3 mutations.

METHODS

Patients with HPE and their family members were tested for mutations in HPE-associated genes and the genetic and clinical findings, including those for additional cases found in the literature, were analysed. The results were correlated with a mutation-specific functional assay in zebrafish.

RESULTS

In a cohort of patients (n = 800) with HPE, SIX3 mutations were found in 4.7% of probands and additional cases were found through testing of relatives. In total, 138 cases of HPE were identified, 59 of whom had not previously been clinically presented. Mutations in SIX3 result in more severe HPE than in other cases of non-chromosomal, non-syndromic HPE. An over-representation of severe HPE was found in patients whose mutations confer greater loss of function, as measured by the functional zebrafish assay. The gender ratio in this combined set of patients was 1.5:1 (F:M) and maternal inheritance was almost twice as common as paternal. About 14% of SIX3 mutations in probands occur de novo. There is a wide intrafamilial clinical range of features and classical penetrance is estimated to be at least 62%.

CONCLUSIONS

Our data suggest that SIX3 mutations result in relatively severe HPE and that there is a genotype-phenotype correlation, as shown by functional studies using animal models.

Use of the QuantiFERON-TB Gold test to confirm latent tuberculosis infection in a Canadian tuberculosis clinic

SETTING

Capital Health Tuberculosis (TB) Clinic, Edmonton, Alberta, Canada.

OBJECTIVE

To analyze the QuantiFERON-TB Gold In-Tube test (QFT) results after implementation as a routine test for tuberculin skin test (TST) positive patients.

DESIGN

From November 2004 until January 2007, patients who were TST-positive and were eligible for preventive treatment based on Canadian guidelines, were offered a QFT.

RESULTS

Of 1446 TST-positive patients, only 566 (39.6%) were QFT-positive. Categorized by reason for TST testing, 43.1% of 304 contacts, 32.8% of 348 employment screens and 24.2% of 298 post secondary school screens were QFT-positive. In contrast, 59.7% of 290 immigration screens were QFT-positive. A multivariate analysis found that QFT positivity was associated with older age, larger TST size, high-incidence TB region of birth, history of TB and chest X-ray findings suggestive of previous TB.

CONCLUSION

Implementation of the QFT as a secondary test for latent TB infection (LTBI) can significantly reduce the number of patients given LTBI treatment in a low-incidence country such as Canada.

A comparative study on urinary purine derivative excretion of yak (Bos grunniens), cattle (Bos taurus), and crossbred (Bos taurus x Bos grunniens) in the Qinghai-Tibetan plateau, China

Two experiments were conducted to determine the urinary purine derivative (PD) excretion rates and to analyze potential variations in PD excretions between yak, Tibetan indigenous cattle, and their crossbreds under similar ecological environment, and to develop prediction equations based on PD excretion for estimating rumen microbial protein supply. Three Tibetan castrated male yaks, and similar numbers of indigenous cattle and their crossbreds, were used in a fasting trial followed by a feeding trial, using three 3 x 3 Latin squares (1 for each breedtype), to measure responses of PD excretion to different feeding levels. The results showed that i) daily endogenous PD excretion for yak, indigenous cattle, and their crossbreds was 134, 163, and 138 micromol/kg of BW(0.75) (P = 0.38), respectively; and ii) crossbreds have greater PD excretion rate per unit digestible OM intake than indigenous cattle (P = 0.03). However, there were no significant differences between yaks and the crossbreds (P = 0.24) or between yaks and the indigenous cattle (P = 0.25). The proportion of allantoin to total PD in urine ranged from 0.83 to 0.88, with the crossbreds having greater values compared with the 2 parents (P = 0.03). Daily glomerular filtration rate, calculated using endogenous creatinine as an internal marker, for the above animals was 3.85, 4.23, and 3.61 L/kg of BW(0.75), respectively, in fasting trial (P = 0.59). The alpine animals may develop special regulating mechanisms in the kidney in terms of glomerular filtration rate and PD excretion, which would help the animals in adapting to the harsh environment of the Qinghai-Tibetan plateau.

Multiple frequency modulation for low-light atom measurements in an optical cavity

We present a frequency modulation scheme to detect atoms dispersively in a high-finesse optical cavity at low-light levels with immunity to cavity length fluctuations. We use multiple cavity resonances to provide common mode noise rejection, keeping the high intensity carrier off-resonant from all cavity modes. The method has applications in atomic squeezed state generation and quantum metrology.