Long-Term Protective Effect of Tuberculosis Preventive Therapy in a Medium/High Tuberculosis Incidence Setting

BACKGROUND

The duration of the protective effect of tuberculosis preventive therapy (TPT) is controversial. Some studies have found that the protective effect of TPT is lost after cessation of therapy among people with human immunodeficiency virus (HIV) in settings with very high tuberculosis incidence, but others have found long-term protection in low-incidence settings.

METHODS

We estimated the incidence rate (IR) of new tuberculosis disease for up to 12 years after randomization to 4 months of rifampin or 9 months of isoniazid, among 991 Brazilian participants in a TPT trial in the state of Rio de Janeiro, with an incidence of 68.6/100 000 population in 2022. The adjusted hazard ratios (aHRs) of independent variables for incident tuberculosis were calculated.

RESULTS

The overall tuberculosis IR was 1.7 (95% confidence interval [CI], 1.01- 2.7) per 1000 person-years (PY). The tuberculosis IR was higher among those who did not complete TPT than in those who did (2.9 [95% CI, 1.3-5.6] vs 1.1 [.4-2.3] per 1000 PY; IR ratio, 2.7 [1.0-7.2]). The tuberculosis IR was higher within 28 months after randomization (IR, 3.5 [95% CI, 1.6-6.6] vs 1.1 [.5-2.1] per 1000 PY between 28 and 143 months; IR ratio, 3.1 [1.2-8.2]). Treatment noncompletion was the only variable associated with incident tuberculosis (aHR, 3.2 [95% CI, 1.1-9.7]).

CONCLUSIONS

In a mostly HIV-noninfected population, a complete course of TPT conferred long-term protection against tuberculosis.

Sustainability and impact of an intervention to improve initiation of tuberculosis preventive treatment: results from a follow-up study of the ACT4 randomized trial

Background

In a cluster randomized trial (clinicaltrials.gov: NCT02810678) a flexible but comprehensive health system intervention significantly increased the number of household contacts (HHC) identified and started on tuberculosis preventive treatment (TPT). A follow-up study was conducted one year later to test the hypotheses that these effects were sustained, and were reproducible with a simplified intervention.

Methods

We conducted a follow-up study from May 1, 2018 until April 30, 2019, as part of a multinational cluster randomized trial. Eight sites in 4 countries that had received the intervention in the original trial received no further intervention; eight other sites in the same countries that had not received the intervention (control sites in the original trial) now received a simplified version of the intervention. This consisted of repeated local evaluation of the Cascade of care for TB infection, and stakeholder decision making. The number of HHC identified and starting TPT were repeatedly measured at all 16 sites and expressed as rates per 100 newly diagnosed index TB patients. The sustained effect of the original intervention was estimated by comparing these rates after the intervention in the original trial with the last 6 months of the follow-up study. The reproducibility was estimated by comparing the pre-post intervention changes in rates at sites receiving the original intervention with the pre-post changes in rates at sites receiving the later, simplified intervention.

Findings

With regard to the sustained impact of the original intervention, compared to the original post-intervention period, the number of HHC identified and treated per 100 newly diagnosed TB patients was 10 more (95% confidence interval: 84 fewer to 105 more), and 1 fewer (95% CI: 22 fewer to 20 more) respectively up to 14 months after the end of the original intervention. With regard to the reproducibility of the simplified intervention, at sites that had initially served as control sites, the number of HHC identified and treated per 100 TB patients increased by 33 (95% CI: -32, 97), and 16 (-69, 100) from 3 months before, to up to 6 months after receiving a streamlined intervention, although differences were larger, and significant if the post-intervention results were compared to all pre-intervention periods.

Interpretation

Up to one year after it ended, a health system intervention resulted in sustained increases in the number of HHC identified and starting TPT. A simplified version of the intervention was associated with non-significant increases in the identification and treatment of HHC. Inferences are limited by potential bias due to other temporal effects, and the small number of study sites.

Funding

Funded by the Canadian Institutes of Health Research (Grant number 143350).

Gender Equality in Plastic Surgery Training: A Canadian Nationwide Cross-sectional Analysis

Introduction: One of the important factors in achieving gender equity is ensuring equitable surgical training for all. Previous studies have shown that females get significantly lower surgical exposure than males in certain surgical specialties. Gender gap in surgical exposure has never been assessed in plastic surgery. To that end, the goal of this study was to assess if there are any differences in plastic surgery training between male and female residents. Methods: A survey was sent to all plastic surgery residency programs in Canada to assess the No. of surgeries residents operated on as a co-surgeon or primary assistant during their training. The survey also assessed career goals, level of interest in the specialty, and subjective perception of gender bias. Results: A total of 89 plastic surgery residents (59.3% participation rate) completed the survey and were included in the study. The average No. of reconstructive cases residents operated on as a co-surgeon or primary assistant was 245 ± 312 cases. There was no difference in either reconstructive or aesthetic surgery case logs between male and female residents (p > .05). However, a significantly larger proportion of females (39%) compared to males (4%) felt that their gender limited their exposure to surgical cases and led to a worsening of their overall surgical training (p < .001). Finally, a larger proportion of male residents were interested in academic careers while a larger proportion of female residents were interested in a community practice (p = .024). Conclusion: While there is no evidence of differences in the volume of logged cases between genders, female surgical residents still feel that their respective gender limits their overall surgical training. Gender inequalities in training should be addressed by residency programs.

GeneXpert or chest-X-ray or tuberculin skin testing for household contact assessment (GXT): protocol for a cluster-randomized trial

Background

The World Health Organization recommends tuberculosis (TB) preventive treatment (TPT) for all people living with HIV (PLH) and household contacts (HHC) of index TB patients. Tests for TB infection (TBI) or to rule out TB disease (TBD) are preferred, but if not available, this should not be a barrier if access to these tests is limited for high-risk people, such as PLH and HHC under 5 years old. There is equipoise on the need for these tests in different risk populations, especially HHC aged over 5.

Methods

This superiority cluster-randomized multicenter trial with three arms of equal size compares, in Benin and Brazil, three strategies for HHC investigation aged 0–50: (i) tuberculin skin testing (TST) or interferon gamma release assay (IGRA) for TBI and if positive, chest X-Ray (CXR) to rule out TBD in persons with positive TST or IGRA; (ii) same as (i) but GeneXpert (GX) replaces CXR; and (iii) no TBI testing. CXR for all; if CXR is normal, TPT is recommended. All strategies start with symptom screening. Clusters are defined as HHC members of the same index patients with newly diagnosed pulmonary TBD. The main outcome is the proportion of HHC that are TPT eligible who start TPT within 3 months of the index TB patient starting TBD treatment. Societal costs, incidence of severe adverse events, and prevalence of TBD are among secondary outcomes. Stratified analyses by age (under versus over 5) and by index patient microbiological status will be conducted.

All participants provide signed informed consent. The study was approved by the Research Ethic Board of the Research Institute of the McGill University Health Centre, the Brazilian National Ethical Board CONEP, and the “Comité Local d’Éthique Pour la Recherche Biomédicale (CLERB) de l’Université de Parakou,” Benin. Findings will be submitted for publication in major medical journals and presented in conferences, to WHO and National and municipal TB programs of the involved countries.

Discussion

This randomized trial is meant to provide high-quality evidence to inform WHO recommendations on investigation of household contacts, as currently these are based on very low-quality evidence.

Trial registration

ClinicalTrials.gov NCT04528823.

A public health approach to increase treatment of latent TB among household contacts in Brazil

SETTING: Two consecutive trials were conducted to evaluate the effectiveness of a public health approach to identify and correct problems in the care cascade for household contacts (HHCs) of TB patients in three Brazilian high TB incidence cities.METHODS: In the first trial, 12 clinics underwent standardised evaluation using questionnaires administered to TB patients, HHCs and healthcare workers, and analysis of the cascade of latent TB care among HHCs. Six clinics were then randomised to receive interventions to strengthen management of latent TB infection (LTBI), including in-service training provided by nurses, work process organisation and additional clinic-specific solutions. In the second trial, a similar but streamlined evaluation was conducted in two clinics, who then received initial and subsequent intensive in-service training provided by a physician.RESULTS: In the evaluation phase of both trials, many HHCs were identified, but few started LTBI treatment. After the intervention, the number of HHCs initiating treatment per 100 active TB patients increased by 10 (95%CI - 11 to 30) in the first trial, and by 44 (95%CI 26 to 61) in the second trial.DISCUSSION: A public health approach with standardised evaluation, local decisions for improvements, followed by intensive initial and in-service training appears promising for improved LTBI management.

Effectiveness and cost-effectiveness of a health systems intervention for latent tuberculosis infection management (ACT4): a cluster-randomised trial

BACKGROUND

Reaching the UN General Assembly High-Level Meeting on Tuberculosis target of providing tuberculosis preventive treatment to at least 30 million people by 2022, including 4 million children under the age of 5 years and 20 million other household contacts, will require major efforts to strengthen health systems. The aim of this study was to evaluate the effectiveness and cost-effectiveness of a health systems intervention to strengthen management for latent tuberculosis infection (LTBI) in household contacts of confirmed tuberculosis cases.

METHODS

ACT4 was a cluster-randomised, open-label trial involving 24 health facilities in Benin, Canada, Ghana, Indonesia, and Vietnam randomly assigned to either a three-phase intervention (LTBI programme evaluation, local decision making, and strengthening activities) or control (standard LTBI care). Tuberculin and isoniazid were provided to control and intervention sites if not routinely available. Randomisation was stratified by country and restricted to ensure balance of index patients with tuberculosis by arm and country. The primary outcome was the number of household contacts who initiated tuberculosis preventive treatment at each health facility within 4 months of the diagnosis of the index case, recorded in the first or last 6 months of our 20-month study. To ease interpretation, this number was standardised per 100 newly diagnosed index patients with tuberculosis. Analysis was by intention to treat. Masking of staff at the coordinating centre and sites was not possible; however, those analysing data were masked to assignment of intervention or control. An economic analysis of the intervention was done in parallel with the trial. ACT4 is registered at ClinicalTrials.gov, NCT02810678.

FINDINGS

The study was done between Aug 1, 2016, and March 31, 2019. During the first 6 months of the study the crude overall proportion of household contacts initiating tuberculosis preventive treatment out of those eligible at intervention sites was 0·21. After the implementation of programme strengthening activities, the proportion initiating tuberculosis preventive treatment increased to 0·35. Overall, the number of household contacts initiating tuberculosis preventive treatment per 100 index patients with tuberculosis increased between study phases in intervention sites (adjusted rate difference 60, 95% CI 4 to 116), while control sites showed no statistically significant change (-12, -33 to 10). There was a difference in rate differences of 72 (95% CI 10 to 134) contacts per 100 index patients with tuberculosis initiating preventive treatment associated with the intervention. The total cost for the intervention, plus LTBI clinical care per additional contact initiating treatment was estimated to be CA$1348 (range 724 to 9708).

INTERPRETATION

A strategy of standardised evaluation, local decision making, and implementation of health systems strengthening activities can provide a mechanism for scale-up of tuberculosis prevention, particularly in low-income and middle-income countries.

FUNDING

Canadian Institutes of Health Research.

Effects of programmatic interventions to improve the management of latent tuberculosis: a follow up study up to five months after implementation

Background

Less than 19% of those needing tuberculosis (TB) preventive treatment complete it, due to losses in several steps of the cascade of care for latent TB infection. A cluster randomized trial of a programmatic public health intervention to improve management of latent TB infection in household contacts was conducted in Rio de Janeiro. Interventions included contact registry, initial and in-service training, and a TB booklet. We conducted a follow-up study starting one month after the conclusion of this trial, to measure the effect of interventions implemented, and to identify remaining barriers and facilitators to latent TB infection treatment, from different perspectives.

Methods

In two health clinics in Rio de Janeiro that received the interventions in the trial, data for the latent TB infection cascade of care for household contacts was collected over a five-month period. The number of household contacts initiating treatment per 100 index-TB patients was compared with the cascade of care data obtained before and during the intervention trial. Semi-structured open-ended questionnaires were administered to healthcare workers, household contacts and index-TB patients regarding knowledge and perceptions about TB and study interventions.

Results

In this follow-up study, 184 household contacts per 100 index-TB patients were identified. When compared to the intervention period, there were 65 fewer household contacts per 100 index-TB patients, (95% CI -115, − 15) but the number starting latent TB infection treatment was sustained (difference -2, 95% CI -8,5). A total of 31 index-TB patients, 22 household contacts and 19 health care workers were interviewed. Among index-TB patients, 61% said all their household contacts had been tested for latent TB infection. All health care workers said it was very important to test household contacts, and 95% mentioned that possessing correct knowledge on the benefits of latent TB infection treatment was the main facilitator to enable them to recommend this treatment.

Conclusion

In this follow-up study, we observed a sustained effect of interventions to strengthen the latent TB infection cascade of care on increasing the number of household contacts starting latent TB infection treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10195-z.

Solutions to improve the latent tuberculosis Cascade of Care in Ghana: a longitudinal impact assessment

Background

Loss of patients in the latent tuberculosis infection (LTBI) cascade of care is a major barrier to LTBI management. We evaluated the impact and acceptability of local solutions implemented to strengthen LTBI management of household contacts (HHCs) at an outpatient clinic in Ghana.

Methods

Local solutions to improve LTBI management were informed by a baseline evaluation of the LTBI cascade and questionnaires administered to index patients, HHCs, and health care workers at the study site in Offinso, Ghana. Solutions aimed to reduce patient costs and improve knowledge. We evaluated the impact and acceptability of the solutions. Specific objectives were to: 1) Compare the proportion of eligible HHCs completing each step in the LTBI cascade of care before and after solution implementation; 2) Compare knowledge, attitude, and practices (KAP) before and after solution implementation, based on responses of patients and health care workers (HCW) to structured questionnaires; 3) Evaluate patient and HCW acceptability of solutions using information obtained from these questionnaires.

Results

Pre and Post-Solution LTBI Cascades included 58 and 125 HHCs, respectively. Before implementation, 39% of expected < 5-year-old HHCs and 66% of ≥5-year-old HHCs were identified. None completed any further cascade steps. Post implementation, the proportion of eligible HHCs who completed identification, assessment, evaluation, and treatment initiation increased for HHCs < 5 to 94, 100, 82, 100%, respectively, and for HHCs ≥5 to 96, 69, 67, 100%, respectively. Pre and Post-Solutions questionnaires were completed by 80 and 95 respondents, respectively. Study participants most frequently mentioned financial support and education as the solutions that supported LTBI management.

Conclusion

Implementation of locally selected solutions was associated with an increase in the proportion of HHCs completing all steps in the LTBI cascade. Tuberculosis programs should consider prioritizing financial support, such as payment for chest x-rays, to support LTBI cascade completion.

Resource implications of the latent tuberculosis cascade of care: a time and motion study in five countries

BACKGROUND

The End TB Strategy calls for global scale-up of preventive treatment for latent tuberculosis infection (LTBI), but little information is available about the associated human resource requirements. Our study aimed to quantify the healthcare worker (HCW) time needed to perform the tasks associated with each step along the LTBI cascade of care for household contacts of TB patients.

METHODS

We conducted a time and motion (TAM) study between January 2018 and March 2019, in which consenting HCWs were observed throughout a typical workday. The precise time spent was recorded in pre-specified categories of work activities for each step along the cascade. A linear mixed model was fit to estimate the time at each step.

RESULTS

A total of 173 HCWs in Benin, Canada, Ghana, Indonesia, and Vietnam participated. The greatest amount of time was spent for the medical evaluation (median: 11 min; IQR: 6-16), while the least time was spent on reading a tuberculin skin test (TST) (median: 4 min; IQR: 2-9). The greatest variability was seen in the time spent for each medical evaluation, while TST placement and reading showed the least variability. The total time required to complete all steps along the LTBI cascade, from identification of household contacts (HHC) through to treatment initiation ranged from 1.8 h per index TB patient in Vietnam to 5.2 h in Ghana.

CONCLUSIONS

Our findings suggest that the time requirements are very modest to perform each step in the latent TB cascade of care, but to achieve full identification and management of all household contacts will require additional human resources in many settings.

Enhancing the public health impact of latent tuberculosis infection diagnosis and treatment (ACT4): protocol for a cluster randomised trial

INTRODUCTION

Treatment of latent tuberculosis (TB) infection (LTBI) is an important component of the End-TB strategy. However, the number of individuals who successfully complete LTBI treatment remains low as there are losses at all steps in the LTBI 'cascade-of-care'. The reasons for these losses are variable and highly dependent on the setting. We have planned a trial of a standardised public health approach to strengthen the management of household contacts (HHCs) of newly diagnosed patients with pulmonary TB. Assessing costs related to approach is a secondary objective of the study.

METHODS AND ANALYSIS

A cluster randomised trial will be conducted in 24 randomisation units (health facilities or groups of health facilities) in five countries. In Phase 1, at intervention sites, we will conduct a standardised assessment of the current LTBI programme, with a focus on cascade-of-care endpoints. Standardised open-ended questionnaires on practices, knowledge, attitudes and beliefs regarding TB prevention are then administered to key patient groups and healthcare workers. At each site, local stake-holders will review study findings and select solutions based on their acceptability, cost and effectiveness. In Phase 2, intervention clinics will implement the selected solutions, along with contact measurement registries and regular in-service LTBI management training. Control sites will continue their usual LTBI care with no explicit evaluation, strengthening or training activities. The primary study outcome is the number of HHC initiating LTBI treatment per newly diagnosed active TB patient, within 3 months of diagnosis of the index patient. An intention-to-treat analysis will be performed, using a Poisson regression approach.

ETHICS AND DISSEMINATION

Ethics approval from the MUHC ethical review board (ERB) was obtained in November 2015. During the study standardised tools will be developed and made publicly available. Key study findings and novel methodologic contributions will be detailed in publications and other dissemination activities.

TRIAL REGISTRATION NUMBER

NCT02810678; Pre-Results.

Four Months of Rifampin or Nine Months of Isoniazid for Latent Tuberculosis in Adults

BACKGROUND

A 9-month regimen of isoniazid can prevent active tuberculosis in persons with latent tuberculosis infection. However, the regimen has been associated with poor adherence rates and with toxic effects.

METHODS

In an open-label trial conducted in nine countries, we randomly assigned adults with latent tuberculosis infection to receive treatment with a 4-month regimen of rifampin or a 9-month regimen of isoniazid for the prevention of confirmed active tuberculosis within 28 months after randomization. Noninferiority and potential superiority were assessed. Secondary outcomes included clinically diagnosed active tuberculosis, adverse events of grades 3 to 5, and completion of the treatment regimen. Outcomes were adjudicated by independent review panels.

RESULTS

Among the 3443 patients in the rifampin group, confirmed active tuberculosis developed in 4 and clinically diagnosed active tuberculosis developed in 4 during 7732 person-years of follow-up, as compared with 4 and 5 patients, respectively, among 3416 patients in the isoniazid group during 7652 person-years of follow-up. The rate differences (rifampin minus isoniazid) were less than 0.01 cases per 100 person-years (95% confidence interval [CI], -0.14 to 0.16) for confirmed active tuberculosis and less than 0.01 cases per 100 person-years (95% CI, -0.23 to 0.22) for confirmed or clinically diagnosed tuberculosis. The upper boundaries of the 95% confidence interval for the rate differences of the confirmed cases and for the confirmed or clinically diagnosed cases of tuberculosis were less than the prespecified noninferiority margin of 0.75 percentage points in cumulative incidence; the rifampin regimen was not superior to the isoniazid regimen. The difference in the treatment-completion rates was 15.1 percentage points (95% CI, 12.7 to 17.4). The rate differences for adverse events of grade 3 to 5 occurring within 146 days (120% of the 4-month planned duration of the rifampin regimen) were -1.1 percentage points (95% CI, -1.9 to -0.4) for all events and -1.2 percentage points (95% CI, -1.7 to -0.7) for hepatotoxic events.

CONCLUSIONS

The 4-month regimen of rifampin was not inferior to the 9-month regimen of isoniazid for the prevention of active tuberculosis and was associated with a higher rate of treatment completion and better safety. (Funded by the Canadian Institutes of Health Research and the Australian National Health and Medical Research Council; ClinicalTrials.gov number, NCT00931736 .).

Safety and Side Effects of Rifampin versus Isoniazid in Children

BACKGROUND

The treatment of latent infection with Mycobacterium tuberculosis is important in children because of their vulnerability to life-threatening forms of tuberculosis disease. The current standard treatment - 9 months of isoniazid - has been associated with poor adherence and toxic effects, which have hampered the effectiveness of the drug. In adults, treatment with 4 months of rifampin has been shown to be safer and to have higher completion rates than 9 months of isoniazid.

METHODS

In this multicenter, open-label trial, we randomly assigned 844 children (<18 years of age) with latent M. tuberculosis infection to receive either 4 months of rifampin or 9 months of isoniazid. The primary outcome was adverse events of grade 1 to 5 that resulted in the permanent discontinuation of a trial drug. Secondary outcomes were treatment adherence, side-effect profile, and efficacy. Independent review panels whose members were unaware of trial-group assignments adjudicated all adverse events and progression to active tuberculosis.

RESULTS

Of the children who underwent randomization, 829 were eligible for inclusion in the modified intention-to-treat analysis. A total of 360 of 422 children (85.3%) in the rifampin group completed per-protocol therapy, as compared with 311 of 407 (76.4%) in the isoniazid group (adjusted difference in the rates of treatment completion, 13.4 percentage points; 95% confidence interval [CI], 7.5 to 19.3). There were no significant between-group differences in the rates of adverse events, with fewer than 5% of the children in the combined groups with grade 1 or 2 adverse events that were deemed to be possibly related to a trial drug. Active tuberculosis, including 1 case with resistance to isoniazid, was diagnosed in 2 children in the isoniazid group during 542 person-years of follow-up, as compared with no cases in the rifampin group during 562 person-years (rate difference, -0.37 cases per 100 person-years; 95% CI, -0.88 to 0.14).

CONCLUSIONS

Among children under the age of 18 years, treatment with 4 months of rifampin had similar rates of safety and efficacy but a better rate of adherence than 9 months of treatment with isoniazid. (Funded by the Canadian Institutes of Health Research and Conselho Nacional de Pesquisa; ClinicalTrials.gov number, NCT00170209 .).

Incidence of serious side effects from first-line antituberculosis drugs among patients treated for active tuberculosis

Major adverse reactions to antituberculosis drugs can cause significant morbidity, and compromise treatment regimens for tuberculosis (TB). Among patients treated for active TB we estimated the incidence, and risk factors, of major side effects from first-line anti-TB drugs. Side effects, resulting in modification or discontinuation of therapy, or hospitalization, were attributed on the basis of resolution after withdrawal, and/or recurrence with rechallenge. Among 430 patients treated between 1990 and 1999, the incidence of all major adverse effects was 1.48 per 100 person-months of exposure (95% confidence interval [95% CI], 1.31 to 1.61) for pyrazinamide, compared with 0.49 (95% CI, 0.42 to 0.55) for isoniazid, 0.43 (95% CI, 0.37 to 0.49) for rifampin, and 0.07 (95% CI, 0.04 to 0.10) for ethambutol. Occurrence of any major side effect was associated with female sex (adjusted hazard ratio, 2.5; 95% CI, 1.3 to 4.7), age over 60 years (adjusted hazard ratio, 2.9; 95% CI, 1.3 to 6.3), birthplace in Asia (adjusted hazard ratio, 2.5; 95% CI, 1.3 to 5.0), and human immunodeficiency virus-positive status (adjusted hazard ratio, 3.8; 95% CI, 1.05 to 13.4). Pyrazinamide-associated adverse events were associated with age over 60 years (adjusted hazard ratio, 2.6; 95% CI, 1.01 to 6.6) and birthplace in Asia (adjusted hazard ratio, 3.4; 95% CI, 1.4 to 8.3), whereas rifampin-associated adverse events were associated with age over 60 years (adjusted hazard ratio, 3.9; 95% CI, 1.02 to 14.9) and human immunodeficiency virus-positive status (adjusted hazard ratio, 8.0; 95% CI, 1.5 to 43). The incidence of pyrazinamide-induced hepatotoxicity and rash during treatment for active TB was substantially higher than with the other first-line anti-TB drugs, and higher than previously recognized.

The flexible contour backrest: a new design concept for wheelchairs

Studies have shown that the use of a conventional sling backrest in a wheelchair may have a negative impact on the posture and health of users. To avoid such problems, this backrest is often replaced by a back cushion on a rigid surface. However, the use of the latter deprives many wheelchair users of the advantages provided by the sling backrest (easy folding, lightweight, low cost, unobtrusive, simplicity of design). In an effort to maintain these features while providing adequate posture, a new backrest was designed according to specific criteria. The "flexible contour backrest" has been developed so that it can be adapted to a person's back contour with stays, adjustable straps, and curved back posts. Preliminary comparisons done by some experts with commercially available backrests showed that design criteria were reached at 62.9% by the back cushion on a rigid surface, at 64% by the sling backrest, and at 67.7% by the adjustable-tension backrest. On the other hand, design criteria were reached at 80% by the new flexible contour backrest because its design brings together most of the positive features provided by these other backrests (easy to fold, light weight, unobtrusive, airy) as well as providing adequate posture and better fit to the user's morphology.

[Training of interviewers in the utilization of standardized questionnaires in psychiatry: studies realized with the Present State Examination (PSE)]

Interview questionnaires offer more validity than self-administered format in exploring psychopathological or psychosocial phenomena of interest in psychiatric research. If used, special care needs to be paid to interviewers' training and ensuring that they maintain their reliability. No widespread training standards exist and each schedule may carry its own procedure. Our aims are to indicate how we trained interviewers with the French version of the Present State Examination (Wing, Cooper and Sartorius, 1974) and how we checked and kept acceptable interraters reliability during one study. We will provide data on the interraters reliability during the training and the study, as well as the test-retest reliability. These results will be used to support some guidelines when using this sort of psychiatric research questionnaires in order to ensure comparability both within the study and between studies.

Mastication in the rabbit: a description of movement and muscle activity

1. Mastication was studied in awake rabbits that had previously been prepared for chronic recording of jaw movement and jaw muscle electromyography (EMG) under general anesthesia. Data were stored on tape and replayed for computer-assisted analysis. Most data was taken from the mastication of rabbit chow, but the basic features described in the paper also apply to eating of other foods. The series of movements was divided into cycles, and the phases that compose them, using peaks in the vertical movement, velocity, and acceleration. 2. The whole series of movements from ingestion to swallowing was termed the masticatory sequence. We found, as have others, that the sequence can be divided into three consecutive periods, based on the form of the movements. These were named the preparatory, reduction, and preswallowing series of cycles. 3. The results of earlier studies suggest that the food is transported back to the molar teeth during the preparatory series, ground up during the reduction series, and that the bolus is formed for swallowing during the preswallowing series. 4. The typical cycle of the preparatory series was called type I; it had two phases: opening (O) and fast closing (FC). The jaw-opening muscles were very active during O, but EMG bursts from the closer muscles were small or undefinable during FC. There was not much movement away from the midline in either phase, and the cycles were the shortest in the sequence. 5. The reduction series was predominantly composed of type II cycles. These were of intermediate duration and had three phases [O, a short FC, and a slow closing phase (SC)], during which the pellets were crushed between the molar teeth. The jaw moved toward the working side during FC. At or soon after the start of SC, the closer muscles became very active and continued to contract as the teeth were drawn toward the midline and slightly backwards. 6. The preswallowing series was made up of five-phase cycles that we called type III. These were the longest of the sequence. Jaw opening now occurred in three stages: O1 was the fall from tooth contact to approximately the postural position, O2 was a pause, and O3 was defined as the final movement to maximum opening. The digastric burst occurred during O3. There were again two closing phases, FC and SC, but closer bursts were smaller than in type II, and SC was shorter.(ABSTRACT TRUNCATED AT 400 WORDS)

Activity during mastication of periodontal mechanosensitive neurons of the trigeminal subnucleus oralis of the rabbit

1. The activity of mechanosensitive neurons was examined before and during mastication. One hundred and seventy-eight neurons were recorded in the rostral parts of the trigeminal sensory nuclei of 20 rabbits anesthetized with urethan. Twenty-eight neurons received inputs from the periodontal mechanoreceptors, all on the ipsilateral side. Nineteen had receptive fields that were restricted to one tooth; 2 could be activated from more than 1 tooth, and 6 included parts of the mucosa. Only the latter were spontaneously active. 2. All periodontal neurons with a mandibular input responded to graded electrical stimulation of the inferior alveolar nerve at minimum latencies of less than or equal to 3.4 ms, and approximately half had inputs from the sensorimotor cortex. 3. Almost all periodontal units recorded were found to lie in, or just outside, the dorsal part of the most rostral subdivision of the spinal trigeminal nucleus (subnucleus oralis, pars gamma). None projected to the ipsi- or contralateral thalamus. 4. All periodontal neurons fired during mastication. Those without mucosal receptive fields fired during jaw closure, with almost all activity confined to the slow-closing phase when pressure is applied to the teeth. Injections of local anesthetic showed that input from mucosal fields was responsible for activating neurons in other phases of the cycle. 5. Possible roles in the control of mastication for these periodontal interneurons were discussed.

The role of biotransformation-detoxication in acetone-, 2-butanone-, and 2-hexanone-potentiated chloroform-induced hepatotoxicity

The hepatotoxicity of chloroform (CHCl3) is thought to require biotransformation, by the polysubstrate monooxygenase system (P-450), to a reactive intermediate(s). Therefore, the potentiation of CHCl3-induced hepatotoxicity, which occurs following exposure to certain ketones, may hypothetically be explained by a reduced capacity of the cell to form glutathione conjugates (detoxicate the intermediate) and (or) by an increased rate of reactive intermediate(s) generation secondary to a modification of the P-450 system. To test these hypotheses, liver damage, as indicated by elevation in plasma alanine aminotransferase and ornithine carbamyl transferase activities, was modulated in male Sprague-Dawley rats by varying the time interval (10, 18, 24, 48, 72, 96 h) between acetone, 2-butanone, or 2-hexanone (15 mmol/kg, p.o.) pretreatment and CHCl3 (0.5 mL/kg, p.o.) administration. These data were compared with hepatic glutathione and with various parameters of the polysubstrate monooxygenase system: cytochrome P-450, cytochrome c reductase, cytochrome b5, and microsomal binding of 14CHCl3-derived radiolabel. Reduced detoxication capacity does not appear to be involved as hepatic glutathione levels were not reduced. Globally, a relationship between modifications to the polysubstrate monooxygenase system and potentiation of CHCl3-induced hepatotoxicity appears to exist. The rank order of each ketone's ability to modify P-450 parameters was the same in most instances as that based on peak ability to potentiate CHCl3-induced hepatotoxicity: 2-hexanone greater than 2-butanone greater than or equal to acetone. Therefore, these results suggest that a general relationship exists between the ketone-induced potentiation of CHCl3-induced hepatotoxicity and increased CHCl3 reactive metabolite generation. However, other factors may also contribute to the phenomenon.

Evidence that periodontal pressoreceptors provide positive feedback to jaw closing muscles during mastication

1. Mastication was produced by stimulation of the right motor-sensory cortex of urethan-anesthetized rabbits with 15-s trains of shocks (1-ms duration) at 50 Hz. Movements of the lower jaw and jaw muscle electromyograms (EMGs) were recorded on magnetic tape for later computer analysis. 2. The stimulus site was chosen, and stimulus intensity adjusted, so that stereotyped movements were produced that included a wide swing of the mandible to the left side during jaw closure. 3. Control trials were alternated with trials in which a steel ball (2 mm diam) was thrust between the anterior molar teeth on the left side and left in place for several seconds. 4. When the obstruction was first introduced, a jaw opening reflex was sometimes evoked if the ball struck the buccal surface of the advancing mandibular molar teeth. Thereafter, when the ball was crushed between the occlusal surfaces of the teeth, no jaw opening reflex was seen. 5. Instead, the amplitude and duration of all the jaw closing EMGs increased, beginning at least 12 ms after contact with the ball. This caused a prolongation of the slow closing (SC) phase of the cycle that, coupled with a delay in the start of activity in the digastric muscle (jaw opener), prolonged the cycle by more than 60 ms. 6. During the SC phase of the obstructed trials, the medially directed grinding stroke was exaggerated because of an increase in the contraction of the contralateral zygomaticomandibular and anterior temporal muscles. 7. After collecting data, the sensory nerves to the maxillary and mandibular anterior molar teeth were cut to eliminate feedback from the periodontal pressoreceptors. Control and obstructed trials were repeated. 8. Following denervation, the obstructed cycles were of shorter duration. The mandible still moved to the right during SC in some animals, but the increase in closer muscle EMG activity was much reduced. 9. We conclude that periodontal receptors provide positive feedback to the jaw closing muscles during mastication. This is supplemented by input from other receptors, probably muscle spindles. In addition, an increase in periodontal feedback prolongs the SC phase and the early phases of the opening stroke.