The association between cervical degenerative MRI findings and self-reported neck pain, disability and headache: a cross-sectional exploratory study

BACKGROUND

Neck pain and headache are highly prevalent conditions and leading causes of disability worldwide. Although MRI is widely used in the management of these conditions, there is uncertainty about the clinical significance of cervical MRI findings in patients with neck pain or headache. Therefore, this study aims to investigate the association between cervical degenerative MRI findings and self-reported neck pain, neck disability, and headache.

METHODS

This study was a secondary analysis of a cohort of patients with low back pain aged 18-40 years recruited from a non-surgical outpatient spine clinic. The cervical MRI and outcome measures used in this analysis were collected at a four-year follow-up (2014-2017). Self-reported outcome measures included neck pain intensity, neck disability as measured by the Neck Disability Index, and headache as measured by a single NDI item. Cervical MRI findings included disc degeneration, disc contour changes, and vertebral endplate signal changes (VESC). Multivariable logistic regression analyses, adjusted for age and sex, were used to analyse the associations between MRI findings and neck pain, neck disability, and headache.

RESULTS

A total of 600 participants who underwent MRI and completed the relevant questionnaires at follow-up were included. The median age was 37 years (interquartile range 31-41) and 325 (54%) were female. Of the included participants, 181 (31%) had moderate or severe neck pain, 274 (59%) had moderate or severe neck disability, 193 (42%) reported headaches, and 211 (35%) had one or more cervical degenerative MRI findings. Cervical disc degeneration and disc contour changes were positively associated with moderate or severe neck pain with odds ratio 1.6 (95% CI 1.1-2.4) and 1.6 (1.1-2.3), respectively. VESC was associated with moderate or severe neck disability with odds ratio 3.3 (1.3-8.4). No statistically significant associations were found between the MRI findings assessed and headache.

CONCLUSIONS

In this cross-sectional exploratory study, we found that cervical disc degeneration and disc contour changes were associated with neck pain, and VESC was associated with neck disability. None of the MRI findings were associated with headache. The results suggest that cervical degenerative changes may contribute to the aetiology of neck symptoms, but the associations are modest and cannot guide clinical decisions.

Surgery rates for lumbar spinal stenosis in Denmark between 2002 and 2018: a registry-based study of 43,454 patients

BACKGROUND AND PURPOSE

Over the last decades, many countries have shown increased surgery rates for lumbar spinal stenosis (LSS), but little information is available from Denmark. We describe the development in diagnosis and surgery of LSS in Denmark between 2002 and 2018.

PATIENTS AND METHODS

We collected diagnostic ICD10-codes and surgical procedure codes from private and public hospitals in Denmark from the Danish National Patient Register. Patients diagnosed with LSS and those with surgical procedure codes for decompression surgery with or without fusion were identified. Annual surgery rates were stratified by age, sex, and type of surgery.

RESULTS

During these 17 years, 132,138 patients diagnosed with LSS and 43,454 surgical procedures for LSS were identified. The number of surgical procedures increased by 144%, from 23 to 56 per 100,000 inhabitants. The proportion of patients diagnosed with LSS who received surgery was about 33%, which was almost stable over time. Decompression without fusion increased by 128% from 18 to 40 per 100,000 inhabitants and decompression with fusion increased by 199%, from 5 to 15 per 100,000.

INTERPRETATION

Both the prevalence of LSS diagnoses and LSS surgery rates more than doubled in Denmark between 2002 and 2018. However, the proportion of patients diagnosed with LSS who received surgery remained stable. Decompression surgery with fusion increased at a higher rate than decompression without fusion, although recent evidence suggests no advantage of decompression plus fusion over decompression alone.

Beliefs about back pain and associations with clinical outcomes: a primary care cohort study

OBJECTIVE

To investigate associations between beliefs about low back pain (LBP) at baseline and pain intensity and disability at 2-week, 13-week and 52-week follow-up.

DESIGN

Observational cohort study.

SETTING

Primary care private chiropractic clinics in Denmark.

PARTICIPANTS

A total of 2734 adults consulting a chiropractor for a new episode of LBP, with follow-up data available from 71%, 61% and 52% of the participants at 2, 13 and 52 weeks, respectively.

OUTCOME MEASURES

Beliefs about LBP were measured by the Back Belief Questionnaire (BBQ) before consulting the chiropractor. Pain (Numerical Rating Scale 0-10) and disability (the Roland-Morris Disability Questionnaire) were measured at baseline and after 2, 13 and 52 weeks. Associations were explored using longitudinal linear mixed models estimating interactions between BBQ and time, and by estimating associations between single items of BBQ and 13-week outcomes.

RESULTS

More positive beliefs about LBP were weakly associated with a reduction in pain at 2 weeks (β interaction BBQ#Time=-0.02 (95% CI -0.04 to -0.001)), at 13 weeks (-0.03 (95% CI -0.05 to -0.01)) and at 52 weeks of follow-up (-0.03 (95% CI -0.05 to -0.01); p=0.003). For disability, the association was uncertain (p=0.7). The item 'Back trouble means periods of pain for the rest of one's life' had the strongest association with both reduction in pain (-0.29, 95% CI -0.4 to -0.19, p<0.001) and disability (-2.42, 95% CI -3.52 to -1.33, p<0.001) at 13-week follow-up.

CONCLUSION

Positive beliefs regarding LBP, measured by the BBQ, were associated with a reduction in pain intensity at both short-term and long-term follow-up. However, the association was weak, and the clinical relevance is therefore questionable. No clear association was demonstrated between beliefs and disability. This study did not show promise that back beliefs as measured by the BBQ were helpful for predicting or explaining the course of LBP in this setting.

Symptoms of lumbar spinal stenosis in people with knee or hip osteoarthritis or low back pain: a cross-sectional study of 10,234 participants in primary care

OBJECTIVE

The aims of this study were to evaluate: the proportion of people reporting symptoms associated with lumbar spinal stenosis (LSS) in primary care programs for knee or hip osteoarthritis (OA) or persistent low back pain (LBP) and; the prevalence of self-reported clinical LSS in these three cohorts, according to two sets of adapted criteria.

METHOD

A cross-sectional analysis of baseline data from the Good Life with osteoArthritis in Denmark primary care programs. Self-report LSS symptom questions were administered to participants with knee OA, hip OA, and persistent LBP. The prevalence of eleven LSS symptoms and clinical LSS were calculated for each cohort.

RESULTS

A total of 10,234 participants were included in the analysis. A similar proportion of participants in each cohort were female (69%), with a 6- and 7-year older mean age in the knee and hip cohorts compared to the back cohort. A greater proportion of participants with LBP reported LSS symptoms (range 11-71%) than in the hip (11-50%) and knee (8-40%) cohorts. This pattern was observed for all but one symptom. The same pattern was observed for the prevalence of clinical LSS with less than 10% of people in each cohort satisfying the clinical criteria.

CONCLUSION

Self-reported LSS symptoms are commonly reported by people treated in primary care for knee or hip OA, although not as frequently as reported by those with LBP. Despite symptoms of LSS being common, only a small proportion of people were classified as having self-reported clinical LSS.

Cognitive Functional Therapy for People with Nonspecific Persistent Low Back Pain in a Secondary Care Setting-A Propensity Matched, Case-Control Feasibility Study

BACKGROUND

Effective, inexpensive, and low-risk interventions are needed for patients with nonspecific persistent low back pain (NS-PLBP) who are unresponsive to primary care interventions. Cognitive functional therapy (CFT) is a multidimensional behavioral self-management approach that has demonstrated promising results in primary care and has not been tested in secondary care.

OBJECTIVE

To investigate the effect of CFT and compare it with usual care for patients with NS-PLBP.

DESIGN

Case-control study.

SETTING

A secondary care spine center.

SUBJECTS

Thirty-nine patients received a CFT intervention and were matched using propensity scoring to 185 control patients receiving usual care.

METHODS

The primary outcome was Roland Morris Disability Questionnaire (0-100 scale) score. Group-level differences at six- and 12-month follow-up were estimated using mixed-effects linear regression.

RESULTS

At six-month follow-up, a statistically significant and clinically relevant difference in disability favored the CFT group (-20.7, 95% confidence interval [CI] = -27.2 to -14.2, P < 0.001). Significant differences also occurred for LBP and leg pain, fear, anxiety, and catastrophizing in favor of CFT. At 12-month follow-up, the difference in disability was smaller and no longer statistically significant (-8.1, 95% CI = -17.4 to 1.2, P = 0.086). Differences in leg pain intensity and fear remained significantly in favor of CFT. Treatment satisfaction was significantly higher in the CFT group at six- (93% vs 66%) and 12-month (84% vs 52%) follow-up.

CONCLUSIONS

These findings support that CFT is beneficial for patients with NS-PLBP who are unresponsive to primary care interventions. Subsequent randomized controlled trials could incorporate booster sessions, which may result in larger effects at 12-month follow-up.

A critical appraisal of clinical practice guidelines for the treatment of lumbar spinal stenosis

OBJECTIVE

The aim of the review was to appraise clinical practice guidelines and their recommendations for the treatment of lumbar spinal stenosis.

METHODS

PubMed, Medline, CINAHL, Embase, and Cochrane Central Register of Controlled Trials were searched up until 25/01/2020 for clinical practice guidelines on the management of lumbar spinal stenosis with a systematic process to generate recommendations and were publicly available.

RESULTS

Ten guidelines were included, with a total of 76 recommendations for the treatment of lumbar spinal stenosis. Only 4 of the 10 guidelines were of satisfactory methodological quality according to the AGREE II instrument. Around three-quarters of recommendations (72.4%) were presented with poor evidence, with the remaining 21 presenting (27.6%) fair evidence. No recommendation presented good evidence. Recommendations were made on four types of interventions: surgery, injections, medications, and other nonsurgical treatments, with supporting evidence similar for all four treatment types. Positive recommendations were more common for injections (12/13=92.3%) and surgery (10/15=66%) than for nonsurgical treatments (6/21=28.6%) or medications (1/27=3.75%).

CONCLUSIONS

Ten guidelines on the management of lumbar spinal stenosis were identified in the systematic review, but only four were of adequate methodological quality. While the evidence underpinning the various types of interventions was similar, guidelines tended to endorse surgery and injections but not nonsurgical interventions and medicines. These results support the need for greater rigor and inclusion of steps to minimize bias in the production of guidelines.

Chiropractic conservatism among chiropractic students in Denmark: prevalence and consequences

Background

The chiropractic profession is split between those practicing evidence-based and those whose practice is honed by vitalism. The latter has been coined ‘chiropractic conservatism’. In Denmark, the chiropractic education program is university-based in close collaboration with a medical faculty. We wanted to investigate if such conservative attitudes were present in this environment.

Our objectives were to i) determine the level of chiropractic conservatism, ii) investigate if this was linked to academic year of study, iii) determine the level of clinical appropriateness, and iv) to investigate if this was affected by the level of conservatism among students in a chiropractic program, where the students are taught alongside medical students at the University of Southern Denmark (SDU).

Methods

A cross-sectional survey of 146 (response-rate 76%) 3rd to 5th year pre-graduate students and 1st year postgraduate clinical interns from the chiropractic degree course at the University of Southern Denmark was conducted during autumn of 2019. The students’ levels of conservatism were dichotomized into appropriate/inappropriate, summed up, and used in a linear regression model to determine the association with academic year of study. Thereafter, the conservatism score was categorized into four groups (from low -1- to high -4-). Conservatism groups were cross-tabulated with the ability to answer appropriately on nine cases concerning i) contra-indications, ii) non-indications, and iii) indications for spinal manipulation and analyzed using logistic regression.

Results

Generally, the Danish chiropractic students had low conservatism scores, decreasing with increasing academic year of study. Seventy percent of the students were placed in the two lowest conservative groups. The level of conservatism (categories 1–3) was moderately (but not statistically significantly) associated with an inability to recognize non-indications to treatment. Three outliers (category 4), however, revealed a highly inappropriate handling of the clinical cases.

Conclusions

Chiropractic students enrolled at a university-based course closely integrated with a medical teaching environment are not immune to chiropractic conservatism. However, the course appears to attenuate it and limit its effect on clinical decision-making compared to other educational institutions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12998-020-00352-3.

Prevalence of multimorbid degenerative lumbar spinal stenosis with knee and/or hip osteoarthritis: protocol for a systematic review and meta-analysis

BACKGROUND

Lumbar spinal stenosis (LSS) and knee and hip osteoarthritis (OA) are prevalent conditions in the aging population and published literature suggests they share many symptoms and often are present at the same time in patients. However, no prevalence estimates of multimorbid LSS and knee and/or hip OA are currently available. The primary objective of this systematic review is therefore to estimate the prevalence of multimorbid LSS with knee and/or hip OA using radiological, clinical, and combined case definitions.

METHODS

This systematic review protocol has been designed according to the guidelines from the Cochrane Collaboration and is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols. A comprehensive search will be performed in the following databases: MEDLINE, EMBASE, CENTRAL, and CINAHL. Forward citation tracking will be performed in Web of Science. No restriction for publication date and language will be applied in the literature search, but only articles in English will be included. The search strategy will include the following domains: LSS, knee OA, and hip OA. Retrieved citations will be screened by two authors independently. Disagreements will be discussed until consensus, and a third reviewer will be consulted if consensus cannot be reached. Data extraction and assessment of risk of bias assessment will be done by two authors independently, using a standardized data extraction form and a modified risk of bias tool for prevalence studies. Meta-analysis estimating prevalence with 95% CI will be performed using a random effects model. Meta-regression analyses will be performed to investigate the impact of the following covariates: LSS clinical presentations, sample population, healthcare setting, risk of bias, and other patient characteristics on prevalence estimates for multimorbid LSS and knee and/or hip OA.

DISCUSSION

The results of this review will provide the first estimates of the prevalence of multimorbid LSS and hip and knee OA based on various case definitions. The impact of covariates such as LSS clinical presentations, sample population, healthcare setting, risk of bias, and patient characteristics on prevalence estimates will also be presented.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, awaiting registration.

Exploratory study for clinical signs of MODIC changes in patients with low-back pain in the Netherlands armed forces

Background

Magnetic resonance imaging (MRI) is being used extensively in the search for pathoanatomical factors contributing to low back pain (LBP) such as Modic changes (MC). However, it remains unclear whether clinical findings can identify patients with MC. The purpose of this explorative study was to assess the predictive value of six clinical tests and three questionnaires commonly used with patients with low-back pain (LBP) on the presence of Modic changes (MC).

Methods

A retrospective cohort study was performed using data from Dutch military personnel in the period between April 2013 and July 2016. Questionnaires included the Roland Morris Disability Questionnaire, Numeric Pain Rating Scale, and Pain Self-Efficacy Questionnaire. The clinical examination included (i) range of motion, (ii) presence of pain during flexion and extension, (iii) Prone Instability Test, and (iv) straight leg raise. Backward stepwise regression was used to estimate predictive value for the presence of MC and the type of MC. The exploration of clinical tests was performed by univariable logistic regression models.

Results

Two hundred eighty-six patients were allocated for the study, and 112 cases with medical records and MRI scans were available; 60 cases with MC and 52 without MC. Age was significantly higher in the MC group. The univariate regression analysis showed a significantly increased odds ratio for pain during flexion movement (2.57 [95% confidence interval (CI): 1.08–6.08]) in the group with MC. Multivariable logistic regression of all clinical symptoms and signs showed no significant association for any of the variables. The diagnostic value of the clinical tests expressed by sensitivity, specificity, positive predictive, and negative predictive values showed, for all the combinations, a low area under the curve (AUC) score, ranging from 0.41 to 0.53. Single-test sensitivity was the highest for pain in flexion: 60% (95% CI: 48.3–70.4).

Conclusion

No model to predict the presence of MC, based on clinical tests, could be demonstrated. It is therefore not likely that LBP patients with MC are very different from other LBP patients and that they form a specific subgroup. However, the study only explored a limited number of clinical findings and it is possible that larger samples allowing for more variables would conclude differently.

The association between subgroups of MRI findings identified with latent class analysis and low back pain in 40-year-old Danes

Background

Research into the clinical importance of spinal MRI findings in patients with low back pain (LBP) has primarily focused on single imaging findings, such as Modic changes or disc degeneration, and found only weak associations with the presence of pain. However, numerous MRI findings almost always co-exist in the lumbar spine and are often present at more than one lumbar level. It is possible that multiple MRI findings are more strongly associated with LBP than single MRI findings. Latent Class Analysis is a statistical method that has recently been tested and found useful for identifying latent classes (subgroups) of MRI findings within multivariable datasets. The purpose of this study was to investigate the association between subgroups of MRI findings and the presence of LBP in people from the general population.

Methods

To identify subgroups of lumbar MRI findings with potential clinical relevance, Latent Class Analysis was initially performed on a clinical dataset of 631 patients seeking care for LBP. Subsequently, 412 participants in a general population cohort (the ‘Backs on Funen’ project) were statistically allocated to those existing subgroups by Latent Class Analysis, matching their MRI findings at a segmental level. The subgroups containing MRI findings from the general population were then organised into hypothetical pathways of degeneration and the association between subgroups in the pathways and the presence of LBP was tested using exact logistic regression.

Results

Six subgroups were identified in the clinical dataset and the data from the general population cohort fitted the subgroups well, with a median posterior probability of 93%–100%. These six subgroups described two pathways of increasing degeneration on upper (L1-L3) and lower (L4-L5) lumbar levels. An association with LBP was found for the subgroups describing severe and multiple degenerative MRI findings at the lower lumbar levels but none of the other subgroups were associated with LBP.

Conclusion

Although MRI findings are common in asymptomatic people and the association between single MRI findings and LBP is often weak, our results suggest that subgroups of multiple and severe lumbar MRI findings have a stronger association with LBP than those with milder degrees of degeneration.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-1978-x) contains supplementary material, which is available to authorized users.

The diagnostic value of three sacroiliac joint pain provocation tests for sacroiliitis identified by magnetic resonance imaging

OBJECTIVES

The aim of the current study was to investigate the diagnostic value of three sacroiliac (SI) joint pain provocation tests for sacroiliitis identified by magnetic resonance imaging (MRI) and stratified by gender.

METHOD

Patients without clinical signs of nerve root compression were selected from a cohort of patients with persistent low back pain referred to an outpatient spine clinic. Data from Gaenslen's test, the thigh thrust test, and the long dorsal sacroilia ligament test and sacroiliitis identified by MRI were analysed.

RESULTS

The median age of the 454 included patients was 33 (range 18-40) years and 241 (53%) were women. The prevalence of SI joints with sacroiliitis was 5%. In the whole study group, only the thigh trust test was associated with sacroiliitis, the area under the receiver operating characteristic (ROC) curve (AUC) was 0.58 [95% confidence interval (CI) 0.51-0.65], sensitivity 31% (95% CI 18-47), and specificity 85% (95% CI 82-87). In men, sacroiliitis was associated with all the SI joint tests assessed and multi-test regimens, with the greatest AUC found for at least one positive out of three tests [AUC 0.68 (95% CI 0.56-0.80), sensitivity 56% (95% CI 31-79), and specificity 81% (95% CI 77-85)]. In women, no significant associations were observed between the SI joint tests and sacroiliitis.

CONCLUSIONS

Only in men were the SI joint tests found to be associated with sacroiliitis identified by MRI. Although, the diagnostic value was relatively low, the results indicate that the use of SI joint tests for sacroiliitis may be optimized by gender-separate analyses.

Degenerative Pathways of Lumbar Motion Segments--A Comparison in Two Samples of Patients with Persistent Low Back Pain

Background

Magnetic resonance imaging (MRI) is used to identify spinal pathoanatomy in people with persistent low back pain. However, the clinical relevance of spinal degenerative MRI findings remains uncertain. Although multiple MRI findings are almost always present at the same time, research into the association with clinical outcomes (such as pain) has predominantly focused on individual MRI findings. This study aimed to: (i) investigate how multiple MRI lumbar spine findings cluster together within two different samples of patients with low back pain, (ii) classify these clusters into hypothetical pathways of degeneration based on scientific knowledge of disco-vertebral degeneration, and (iii) compare these clusters and degenerative pathways between samples.

Methods

We performed a secondary cross-sectional analysis on two dissimilar MRI samples collected in a hospital department: (1) data from the spinal MRI reports of 4,162 low back pain patients and (2) data from an MRI research protocol of 631 low back pain patients. Latent Class Analysis was used in both samples to cluster MRI findings from lumbar motion segments. Using content analysis, each cluster was then categorised into hypothetical pathways of degeneration.

Results

Six clusters of MRI findings were identified in each of the two samples. The content of the clusters in the two samples displayed some differences but had the same overall pattern of MRI findings. Although the hypothetical degenerative pathways identified in the two samples were not identical, the overall pattern of increasing degeneration within the pathways was the same.

Conclusions

It was expected that different clusters could emerge from different samples, however, when organised into hypothetical pathways of degeneration, the overall pattern of increasing degeneration was similar and biologically plausible. This evidence of reproducibility suggests that Latent Class Analysis may provide a new approach to investigating the relationship between MRI findings and clinically important characteristics such as pain and activity limitation.

Do MRI findings identify patients with chronic low back pain and Modic changes who respond best to rest or exercise: a subgroup analysis of a randomised controlled trial

BACKGROUND

No previous clinical trials have investigated MRI findings as effect modifiers for conservative treatment of low back pain. This hypothesis-setting study investigated if MRI findings modified response to rest compared with exercise in patients with chronic low back pain and Modic changes.

METHODS

This study is a secondary analysis of a randomised controlled trial comparing rest with exercise. Patients were recruited from a specialised outpatient spine clinic and included in a clinical trial if they had chronic low back pain and an MRI showing Modic changes. All patients received conservative treatment while participating in the trial. Five baseline MRI findings were investigated as effect modifiers: Modic changes Type 1 (any size), large Modic changes (any type), large Modic changes Type 1, severe disc degeneration and large disc herniation. The outcome measure was change in low back pain intensity measured on a 0-10 point numerical rating scale at 14-month follow-up (n = 96). An interaction ≥ 1.0 point (0-10 scale) between treatment group and MRI findings in linear regression was considered clinically important.

RESULTS

The interactions for Modic Type 1, with large Modic changes or with large Modic changes Type 1 were all potentially important in size (-0.99 (95 % CI -3.28 to 1.29), -1.49 (-3.73 to 0.75), -1.49 (-3.57 to 0.58), respectively) but the direction of the effect was the opposite to what we had hypothesized-that people with these findings would benefit more from rest than from exercise. The interactions for severe disc degeneration (0.74 (-1.40 to 2.88)) and large disc herniation (-0.92 (3.15 to 1.31)) were less than the 1.0-point threshold for clinical importance. As expected, because of the lack of statistical power, no interaction term for any of the MRI findings was statistically significant.

CONCLUSIONS

Three of the five MRI predictors showed potentially important effect modification, although the direction of the effect was surprising and confidence intervals were wide so very cautious interpretation is required. Further studies with adequate power are warranted to study these and additional MRI findings as potential effect modifiers for common interventions.

Can pathoanatomical pathways of degeneration in lumbar motion segments be identified by clustering MRI findings

Background

Magnetic Resonance Imaging (MRI) is the gold standard for detailed visualisation of spinal pathological and degenerative processes, but the prevailing view is that such imaging findings have little or no clinical relevance for low back pain. This is because these findings appear to have little association with treatment effects in clinical populations, and mostly a weak association with the presence of pain in the general population.

However, almost all research into these associations is based on the examination of individual MRI findings, despite its being very common for multiple MRI findings to coexist. Therefore, this proof-of-concept study investigated the capacity of a multivariable statistical method to identify clusters of MRI findings and for those clusters to be grouped into pathways of vertebral degeneration.

Methods

This study is a secondary analysis of data from 631 patients, from an outpatient spine clinic, who had been screened for inclusion in a randomised controlled trial. The available data created a total sample pool of 3,155 vertebral motion segments. The mean age of the cohort was 42 years (SD 10.8, range 18–73) and 54% were women.

MRI images were quantitatively coded by an experienced musculoskeletal research radiologist using a detailed and standardised research MRI evaluation protocol that has demonstrated high reproducibility. Comprehensive MRI findings descriptive of the disco-vertebral component of lumbar vertebrae were clustered using Latent Class Analysis. Two pairs of researchers, each containing an experienced MRI researcher, then independently categorised the clusters into hypothetical pathoanatomic pathways based on the known histological changes of discovertebral degeneration.

Results

Twelve clusters of MRI findings were identified, described and grouped into five different hypothetical pathways of degeneration that appear to have face validity.

Conclusions

This study has shown that Latent Class Analysis can be used to identify clusters of MRI findings from people with LBP and that those clusters can be grouped into degenerative pathways that are biologically plausible. If these clusters of MRI findings are reproducible in other datasets of similar patients, they may form a stable platform to investigate the relationship between degenerative pathways and clinically important characteristics such as pain and activity limitation.

Absence of low back pain in patients followed weekly over one year with automated text messages

BACKGROUND

In order to define the onset of a new episode of low back pain (LBP), the definition of a "non-episode" must be clear. De Vet et al reviewed the scientific literature but found no evidence-based definitions of episodes or non-episodes of LBP. However, they suggested that pain-based episodes should be preceded and followed by a period of at least one month without LBP. As LBP is an episodic disease, it is not clear whether a sufficient number of patients with LBP will be LBP-free for at least one month ("non-episode") to justify the use of this duration in the definition of pain free episode.

OBJECTIVES

Two clinical populations were followed weekly over one year making it possible 1) to determine the maximum numbers in a row of weeks without LBP, 2) to determine the prevalence of non-episodes throughout a one-year period, and 3) to find the prevalence of patients who reported to be in a non-episode of LBP at the end of the study.

METHODS

Secondary data were used from two recent clinical studies, in which weekly automated text messages (SMSes) had been collected on the number of days with LBP in the preceding week for one year. Weeks with 0 days of LBP were defined as "zero-weeks" and four zero-weeks in a row were defined as a period without LBP (a"non-episode") according to de Vet et al's suggestion. The study participants, all from the secondary care sector, consisted of: study 1) patients with LBP and Magnetic Resonance Imaging-identified Modic changes and study 2) patients without obvious acute disc problems, Modic changes or other pathologies, who therefore were assumed to have non-specific LBP. Both studies were two-armed intervention studies without a significant difference in outcome between intervention groups. The number of zero-weeks was identified in each participant. Thereafter the numbers of participants who reported at least one non-episode during the study period were identified. Finally, the numbers of participants who had a non-episode at the end of the study were counted. Estimates are reported with their 95% confidence intervals.

RESULTS

The numbers of participants included in the analyses were 80 and 209. Most commonly, no zero weeks were reported, by 65% (55-75) and 56% (49-63) of patients, respectively. The percentages of study participants with at least one non-episode at some time during the course of the study were 20% (11-29) and 18% (15-21. The percentages of participants who were identified as being in a non-episode at the time of the last week of the study were, 5% (95% CI: 0-10) and 4% (1-7) respectively.

CONCLUSIONS

The vast majority of these secondary care sector patients had a profile of more or less constant LBP. The estimates for non-episodes during the study period and at the end of the study were very similar for participants with LBP who also had Modic changes and those with non-specific LBP. It is possible that a definition of pain-free periods is pointless in patients seeking care in the secondary care sector.

Rest versus exercise as treatment for patients with low back pain and Modic changes. A randomized controlled clinical trial

BACKGROUND

Clinical experience suggests that many patients with Modic changes have relatively severe and persistent low back pain (LBP), which typically appears to be resistant to treatment. Exercise therapy is the recommended treatment for chronic LBP, however, due to their underlying pathology, Modic changes might be a diagnostic subgroup that does not benefit from exercise. The objective of this study was to compare the current state-of-the art treatment approach (exercise and staying active) with a new approach (load reduction and daily rest) for people with Modic changes using a randomized controlled trial design.

METHODS

Participants were patients from an outpatient clinic with persistent LBP and Modic changes. They were allocated using minimization to either rest therapy for 10 weeks with a recommendation to rest for two hours daily and the option of using a flexible lumbar belt or exercise therapy once a week for 10 weeks. Follow-up was at 10 weeks after recruitment and 52 weeks after intervention and the clinical outcome measures were pain, disability, general health and global assessment, supplemented by weekly information on low back problems and sick leave measured by short text message (SMS) tracking.

RESULTS

In total, 100 patients were included in the study. Data on 87 patients at 10 weeks and 96 patients at one-year follow-up were available and were used in the intention-to-treat analysis. No statistically significant differences were found between the two intervention groups on any outcome.

CONCLUSIONS

No differences were found between the two treatment approaches, 'rest and reduced load' and 'exercise and staying active', in patients with persistent LBP and Modic changes.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00454792.

Is the presence of modic changes associated with the outcomes of different treatments? A systematic critical review

Background

Modic changes (MCs) have been identified as a diagnostic subgroup associated with low back pain (LBP). The aetiology of MCs is still unknown and there is no effective treatment available. If MCs constitute a specific subgroup of LBP, it seems reasonable to expect different effects from different treatments. The objective of this systematic critical literature review was therefore to investigate if there is evidence in the literature that the presence of MCs at baseline is associated with a favourable outcome depending on the treatment provided for LBP.

Methods

The databases MEDLINE and EMBASE were searched for relevant articles from 1984 to December 2010. A checklist including items related to the research questions and quality of the articles was used for data extraction and quality assessment. Of the 1650 articles found, five (six studies) were included in this review but because the studies were so heterogeneous, the results have been reported separately for each study.

Results

The treatments studied were: lumbar epidural steroid injections (n = 1), lumbar intradiscal steroid injections (n = 2), lumbar disc replacement (n = 1), fusion surgery (n = 1) and exercise therapy (n = 1). One of the two studies investigating treatment with intradiscal steroid injections and the study investigating fusion surgery reported that MCs were positively associated with the outcomes of pain and disability. The other study on lumbar intradiscal steroid injections and the study on lumbar epidural steroid injections reported mixed results, whereas the study on lumbar disc replacement and the study on exercise therapy reported that MCs were not associated with the outcomes of pain and disability.

Conclusions

The available studies on the topic were too few and too heterogeneous to reach a definitive conclusion and it is therefore still unclear if MCs may be of clinical importance when guiding or prescribing the 'right' treatment for a patient with LBP.

Routine versus needs-based MRI in patients with prolonged low back pain: a comparison of duration of treatment, number of clinical contacts and referrals to surgery

Background

The routine use of radiology is normally discouraged in patients with low back pain (LBP). Magnetic Resonance Imaging (MRI) provides clinicians and patients with detailed knowledge of spinal structures and has no known physical side effects. It is possible that insight into the pathological changes in LBP patients could affect patient management. However, to our knowledge, this has never been tested. Until June 2006, all patients at our specialised out-patient public clinic were referred for MRI on the basis of clinical indications, economic constraints, and availability of MRI (the "needs-based MRI" group). As a new approach, we now refer all patients who meet certain criteria for routine up-front MRI before the clinical examination (the "routine MRI" group).

Objectives

The aims of this study were to investigate if these two MRI approaches resulted in differences in: (1) duration of treatment, (2) number of contacts with clinicians, and (3) referral for surgery.

Design

Comparison of two retrospective clinical cohorts.

Method

Files were retrieved from consecutive patients in both groups. Criteria for referral were: (1) LBP or leg pain of at least 3 on an 11-point Numeric Rating Scale, (2) duration of present symptoms from 2 to12 months and (3) age above 18 years. A comparison was made between the "needs-based MRI" and "routine MRI" groups on the outcomes of duration of treatment and use of resources.

Results

In all, 169 "needs-based MRI" and 208 "routine MRI" patient files were identified. The two groups were similar in age, sex, and severity of LBP. However, the median duration of treatment for the "needs-based MRI" group was 160 versus 115 days in the "routine MRI" group (p = 0.0001). The median number of contacts with clinicians for the "needs-based MRI" group was 4 versus 3 for the "routine MRI" group (p = 0.003). There was no difference between the two approaches in frequency of referral for back surgery (p = 0.81). When the direct clinical costs were compared, the "routine MRI" group was less costly but only by €11.

Conclusion

In our clinic, the management strategy of routinely performing an up-front MRI at the start of treatment did reduce the duration of treatment and number of contacts with clinicians, and did not increase the rate of referral for back surgery. Also, the direct costs were not increased.

[Oral ranula. A follow-up study]

Ranula is a cystic swelling of the floor of the mouth, which is usually unilateral and relatively uncommon. The cyst arises from the sublingual salivary gland. We reviewed 14 patients operated in the period 1976-April 1998. There was no recurrence after marsupialization and after extirpation of the sublingual gland. Fourteen percent of the patients had recurrence after extirpation of the cyst. At the follow-up time (average 8.1 years) 18.2% had complications. We suggest that marsupialization/extirpation of the cyst should be primary treatment. In case of recurrence the sublingual gland should be extirpated.

Gravity constraints in infant motor development

The effect of gravity in determining if and when during infancy movements eventuate and the rate at which they develop is unknown. In accordance with intersegmental relationships (Hof, 1992), a muscle moment during infancy would have to develop more rapidly than the gravitational moment before movement could occur. In this investigation, the effect of growth through the influence of gravity on the joint moments in the axial region when infants were in a prone or supine posture was examined. A mathematical model that considers the body to be composed of transverse elliptical cylinders, 1 cm deep and of known density, was used in estimating the mass of the 16 segments of the body. The gravitational moments about 3 joints within the axial region (C7-T1, T12-L1, and the hip) were determined by summation, using the radii from the joint transverse axis to the center of mass of the segments. Infants (N = 27) aged between 9 and 36 weeks at the beginning of the study were tested monthly 6 times, and the effect of growth on the gravitational moments was represented by first-order polynomials. Age x Joint analysis of variance (ANOVA) of the mean slopes of the regressions for the gravitational moments revealed significant main effects for age and joint. The means increased monotonically with the number of segments and decreased as infants aged. The mean slopes of the neck and trunk joints were significantly smaller than that of the hip joint. With increasing age, the gravitational slope was significantly smaller. The changes in the gravitational moments during infancy are seen as likely control parameters effecting phase shifts in motor patterns during development.

Changes in segment mass and mass distribution during pregnancy

The purpose of the study was to evaluate the rates of change in the estimated masses and principal moments of inertia of the body segments during the second and third trimesters of pregnancy. Fifteen subjects, on average 15.1 weeks pregnant, were tested monthly until term. The body was modelled as 16 segments consisting of 2 cm stacked elliptical cylinders sectioned in the transverse plane. Linear regressions were fitted to the segment inertias and regression coefficients determined for the individual growth curves. The mean rate of increase for the lower trunk mass was 0.29 kg per week and 0.0069 kg m2 per week for the transverse axis principal moment. Differences between the means of the segments for rates of change of mass and the three principal moments were then tested. All four ANOVAs used to test the differences were significant. The post hoc analysis established that over the second and third trimesters the lower trunk inertias increased at a greater rate than all other segments and there were no significant differences between the remaining segments. The effect of such changes in the trunk segment masses and principal moments was illustrated by an analysis of intersegmental dynamics during a sit to stand of one pregnant subject whose lower trunk mass increased from 21.6 kg to 28.4 kg. A knowledge of the differences in an individual's segment inertias should lead to a better understanding of how movements are affected during pregnancy.

The application of segment axial density profiles to a human body inertia model

The intention of this study was to construct segment density profiles and compare segment inertias calculated when uniform densities and profile densities are used in a mathematical model. Axial densities from computerized tomography (CT) slices for the body segments of a sample of Chinese females (Zheng et al., Proceedings of the Beijing Asian Games Scientific Congress, 1990) were used to form profiles which could be employed in body segment models. Polynomials based on proportion of segment length were fitted to the reported mean slice densities. These profiles were then used with five widely divergent samples (n = 10); young adult females, young adult males, infants, male children and elderly adults. The mathematical model used is based on an assumption that all segments can be represented by stacked elliptic cylinders. The results show that when the profile densities were substituted for average cadaver densities the increase in the estimated total body mass was less than 0.85%. For the individual segments, use of the profile rather than average density increased the average segment mass estimate by up to 2.7%. The centres of mass and the principal moments were affected by the variations in density along the axis as well as the magnitudes, by up to 0.54 and 3.8%, respectively. Although the effects of using the profiles appear to be small the differences for individual samples, segments and parameters ranged up to 22.5%. It is not possible to decide if average or profile densities produce more accurate estimates of inertia, but the profile allows for axial variation in density and is therefore recommended.

Distribution of mass to the segments of elderly males and females

The comprehensive study of the motion of elderly men and women requires the knowledge about the distribution of the body mass to the segments. Cadaver studies are of older subjects and should provide this information. However, the small samples are primarily male and do not represent the body mass of the elderly. In this study a mathematical model which utilizes the shape of the front and side outlines to calculate segment volume, and subsequently mass, is used. Substantive modifications were made to expedite the original technique [Jensen, J. Biomechanics 11, 349-358 (1978)] by using images from two cameras and digitizing software to determine cross-sectional axes as segments are outlined. The revised technique was used in a study of 12 females and seven males, each 63-75 yr. The mean error for body mass estimation was 0.05% (S.D. 2.96%). The calculated masses were compared to estimated masses based on Dempster [Technical Report 55-159, Wright-Patterson Air Force base, Ohio (1955)], and for females, the Dempster proportions overestimated head and forearm mass and underestimated arm and thigh mass (p > 0.05). For males, the head mass was overestimated. The differences between male and female segment masses were then evaluated. Differences for all segments were significant, with the exception of the upper trunk and thigh. When body mass was considered, the female thigh and foot proportions were larger and the lower trunk, forearm and hand proportions smaller.(ABSTRACT TRUNCATED AT 250 WORDS)

Human morphology: its role in the mechanics of movement

Growth across the lifespan of males and females produces change in the form and structure of the human body which must be recognized in biomechanical models. The different morphologies for age span, gender and racial groupings have been identified and quantified by anthropometrists working primarily with measuring sticks and tapes. These parameters are not the parameters used to solve the dynamics problems of human movement. Models of the body composed of joints and rigid links have been formed and the inertial properties of the segments are required. The research which has been conducted to estimate these segment inertias is incomplete, dispersed, often flawed and inconclusive. However, it is essential that we have a reasonable understanding of the differences in inertia between individuals and changes of inertia within the individual regardless of age, sex and race. Segment inertia parameters can provide valuable insight into growth and the differences between individuals and populations. Segment morphology ranges from embryonic to excessive and each stage of growth or development has potential for the investigation of relationships between shape, size, inertia, weight and movement. The purpose of this paper is to examine research into segment inertias which provides useful information about the differences and changes to be expected. Although some guidance is provided, particularly with respect to bench mark studies, the paper is not intended as a discussion of methodologies. The studies which are pertinent to changes and differences in inertia make it clear that there are many interesting differences between age spans and, within these, differences between males and females and between races. If, in place of the expediency of proportions, segment parameters were measured and integrated into all studies, we would have a more complete representation of morphological changes and differences.

Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis of Canine Urinary Proteins for the Analysis and Differentiation of Tubular and Glomerular Diseases

A preliminary investigation was performed to evaluate the use of a new, noninvasive technique for the localization of canine renal lesions by electrophoresis of urinary proteins. Urine specimens from six clinically healthy, nonproteinuric dogs and 12 dogs with persistent proteinuria were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE). Urine electrophoretic patterns of proteinuric dogs were classified as glomerular (n = 4), tubular (n = 2), or mixed (glomerular and tubular) (n = 6), based on the number and molecular weight of the silver-stained protein bands. Renal tissues from biopsies or necropsies were obtained from eight of the dogs with proteinuric disease. Interpretation of seven of eight electrophoretograms agreed with the histologic interpretation of renal lesions. We concluded SDS PAGE is a potentially valuable technique for detection and localization of renal lesions in dogs with proteinuric disease.

Effects of dietary retinyl acetate on the promotion of hepatic enzyme-altered foci by polybrominated biphenyls in initiated rats

Vitamin A inhibits the development of some chemically-induced tumours. Since polybrominated biphenyls (PBBs) are hepatic tumour promoters and they affect vitamin A homeostasis in rats, we put forward the hypothesis that dietary levels of vitamin A would influence tumour promotion by PBBs. In the study described here, female Sprague-Dawley rats were initiated on day 1 by ip administration of diethylnitrosamine. On day 7 after initiation, the rats were fed a vitamin A-deficient basal diet that was supplemented with either 2000 IU (low-vitamin A) or 200,000 IU (high-vitamin A) retinyl acetate/kg feed. From day 30 after initiation until the end of the study the following PBBs were added to the diets: Firemaster BP-6 (10 ppm), 2,4,5,2',4',5'-hexabromobiphenyl (10 ppm) or 3,4,5,3',4',5'-hexabromobiphenyl (1 ppm). The control animals received low- or high-vitamin A diets containing no PBBs. On day 180, the rats were necropsied, sections of various tissues were stained for histopathological examination and an evaluation of hepatic enzyme-altered foci was performed. Numbers of gamma-glutamyl transpeptidase-positive foci/cm3 liver and the mean volumes of these foci were lower in the high-vitamin A groups than those in the corresponding low-vitamin A groups, but these differences were not significant. The percentage of the liver volume occupied by foci was significantly greater in the low-vitamin A with 345-HBB group than in the corresponding high-vitamin A group. Thus, high dietary levels of vitamin A had some inhibitory effect on the promotion of hepatic-altered foci by 345-HBB in initiated rats.

Effect of hexachlorobiphenyl on vitamin A homeostasis in the rat

Vitamin A status and turnover were examined in rats that had been exposed to chronic dietary treatment of 3,4,5,3',4',5'-hexachlorobiphenyl (HCB), 1 mg/kg diet. HCB caused hepatic depletion and renal accumulation of vitamin A, and a 1.7-fold increase in the serum retinol concentration. Intravenously administered [3H]retinol bound to retinol binding protein-transthyretin complex (RBP-TTR complex) was used to study the dynamics of circulatory retinol in these rats. In HCB-treated rats, the plasma turnover rate of retinol was increased compared to vitamin A-adequate untreated controls. HCB caused a 50% reduction of total radioactivity in liver, and, except for 0.5 h after the [3H]retinol-RBP-TTR dose, the specific activity of the hepatic retinyl ester pool was greater compared to control rats. The kidneys of HCB-treated rats accumulated radioactivity in the retinyl ester fraction. HCB also caused a 50% reduction in adrenal radioactivity compared with control rats. Urinary and fecal excretion of radioactivity was 3-fold higher in HCB-treated rats as compared to controls. Our findings demonstrate that chronic HCB feeding results in expansion of plasma vitamin A mass, in changes of liver and kidney retinol and retinyl ester pool dynamics and in an increased metabolism of vitamin A.

Changes in segment inertia proportions between 4 and 20 years

Growth between 4 and 20 yr produces an increase in body mass and a redistribution of that mass throughout the body. It is the purpose of this investigation to describe changes in the segment mass, radius to the mass centre and radius of gyration for a sample of males, 4-20 yr and the potential effects of these changes on joint reaction forces and moments. The data were collected annually over 9 yr in a mixed longitudinal study completed in 1985. Elliptical zones 2 cm wide were used to model the 16 segments of the body. From these and reported segment densities, mass, the coordinates of the mass centre and the principal moments of inertia were determined for the segments and the body. The parameters reported are the inertia parameters suitable for a sagittal planar analysis with the head and neck considered one segment and values given for other fused segments. The accuracy of the method was judged against the total body mass, and other accuracy estimates from the literature were examined. The parameters are presented as proportions of total mass or segment length. It is clear from the polynomial regressions that there is a substantial redistribution of the mass between segments and this is consistent with the principles of cephalo-caudal and distal-to-proximal development. The proportions for radius and radius of gyration indicate that mass redistribution within segments is comparatively small. The parameters for a 6 yr-old were compared to the parameters expected at 18, 24 and 54 yr and substantial differences noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth of segment principal moments of inertia between four and twenty years

Although there have been numerous studies of the moments of inertia of the body segments using a variety of the techniques, few have reported the principal moments and none has considered the changes in the principal moments during childhood and adolescence. The purpose of this study was to use a mathematical model to determine the intraindividual changes and interindividual differences in the segment principal moments during growth. The body was modelled as 15 segments and composed of transverse elliptical zones of known density. Moments and products of inertia about the segment mass centroid were calculated and the principal moments and axes determined from the ellipsoid of inertia. A mixed longitudinal study of 12 boys over 9 yr for a total of 88 annual recordings covering the age range 4 to 20 yr was conducted. Polynomial regressions fitted to the intraindividual changes showed a similarity in the curves to 10 yr followed by a wide divergence of growth patterns. The changes in the principal moments across age follow the principles of cephalocaudad and distal to proximal development for all three axes. These changes are more accentuated than the changes for segment length, volume, or mass. The results were consistent with principal moments reported for cadavers and young male adult gamma radiation scans as well as estimates based on simplified models of the segments. The magnitude of the changes in principal moments with age makes it essential that appropriate parameters be used in the analysis or simulation of the movements of children and adolescents.

Effect of dietary retinoic acid on circulatory vitamin A homeostasis in polybrominated biphenyl-treated rats

Retinoic acid (RA) supplementation is known to lower the amount of retinol in circulation. In contrast, the feeding of polyhalogenated aromatic hydrocarbons results in an elevated level of circulatory retinol. We investigated the effect of short-term dietary exposure to RA on the amount of serum retinol in female Sprague-Dawley rats fed either a basal diet (control rats) or the basal diet containing 100 mg of polybrominated biphenyls (PBBs)/kg diet (PBB-treated rats). After feeding of the above diets for 137 d, RA (12 mg/kg diet) was included in both the control and PBB-containing diets. The rats were fed the RA-containing diet for 3 d and then killed (d 140). Blood samples were obtained before and after RA treatment. Chronic PBB treatment of rats resulted in lower hepatic vitamin A and higher kidney vitamin A than in control rats. Serum retinol concentration was significantly higher in rats treated with PBB for 137 d than in controls; the subsequent treatment with RA lowered serum retinol to a level that was not different from that of control rats treated with RA. Our observations agree with earlier findings that 1) PBB treatment alters vitamin A homeostasis, and 2) dietary RA lowers the amount of circulatory retinol. An important new observation is that serum retinol homeostasis in PBB-treated rats appears to be regulated by a mechanism similar to that of normal rats. Polyhalogenated aromatic hydrocarbons may thus be useful tools to study the control mechanisms of vitamin A homeostasis.

Vitamin A metabolism in rats chronically treated with 3,3',4,4',5,5'-hexabromobiphenyl

Chronic dietary administration of 3,3',4,4',5,5'-hexabromobiphenyl (HBB), 1 mg/kg diet, caused a decrease in retinol (20-fold) and retinyl esters (23-fold) in the livers of female rats, but resulted in a 6.4-fold increase in retinol and 7.4-fold increase in retinyl esters in the kidneys. Liver acyl-CoA:retinol acyltransferase and retinyl palmitate hydrolase activities were reduced while serum concentration of retinol was unaffected by HBB feeding. Metabolism of a physiological dose of [11-3H]retinyl acetate (10 micrograms), was examined in rats fed either vitamin A-adequate diet, or marginal amounts of vitamin A, or vitamin A-adequate diet containing HBB. A 13-fold greater amount of the administered vitamin A was found in kidneys of HBB-treated rats. In rats fed adequate or low amounts of vitamin A, kidney radioactivity was primarily in the retinol fraction, while in HBB-fed rats the radioactivity was associated mostly with retinyl esters. Fecal and urinary excretion of radioactivity was greatly increased in HBB-treated rats. Chronic HBB feeding results in a loss of ability of liver to store vitamin A, and severely alters the uptake and metabolism of vitamin A in the kidneys. We conclude that HBB causes major disturbances in the regulation of vitamin A metabolism.

Short-term oral administration of polybrominated biphenyls enhances the development of hepatic enzyme-altered foci in initiated rats

FireMaster BP-6 (FM), a commercial mixture of polybrominated biphenyls (PBB), has been shown to act as a tumor promoter in hepatocarcinogenesis assays in rats. Most hepatic tumor promoters must be administered for many weeks or months. Because FM is highly persistent in animal tissues, it was hypothesized that very short-term administration of FM would result in tumor promotion. Female Sprague-Dawley rats weighing 185-215 g were initiated by a two-thirds partial hepatectomy followed by 10 mg diethylnitrosamine/kg body weight (BW) 24 h later. Thirty days later, rats were gavaged with FM in corn oil, at total doses of 0, 13, or 130 mg FM/kg BW. Half the dose was given on d 30, and the remaining half was given 24 h later. At 120 d after gavage the rats were killed and necropsied. Five liver sections from each animal were histochemically stained for gamma-glutamyl transpeptidase-positive enzyme-altered foci (EAF). EAF were significantly increased over control values in initiated rats given 130 mg FM/kg. In animals given 13 mg FM/kg, EAF were increased to a lesser extent but not significantly above controls. Enhancement of these EAF in initiated rats reflects tumor-promoting activity. In this study, 24-h administration of FM in initiated rats was sufficient to enhance hepatic EAF measured 120 d later in an rats was sufficient to enhance hepatic EAF measured 120 d later in an initiation-promotion protocol, and a dose of 13 mg FM/kg was apparently close to a possible no-effect threshold level for enhancement of EAF.

Toxic effects of N-nitrosodiethylamine on nasal tissues of Sprague-Dawley rats and golden Syrian hamsters

The acute necrogenic effects of N-nitrosodiethylamine (NDEA) on nasal tissues of female Sprague-Dawley rats and golden Syrian hamsters were determined. Rats and hamsters were given a single ip dose of 0, 10, 20, 40, or 80 mg NDEA/kg body wt. After 24 hr, the rats and hamsters were killed and tissues were collected. Sections of nasal cavity and liver were evaluated histologically. All doses of NDEA caused inhibition of glycoprotein synthesis in cells of Bowman's glands in the olfactory region of rats and hamsters as determined by the loss of Alcian blue-periodic acid-Schiff staining material. Glycoprotein synthesis in other glands including the lateral nasal glands, maxillary glands, medial nasal glands, and the acinous glands near the vomeronasal organ was not affected by NDEA. Necrosis of Bowman's glands in the olfactory region of the nasal cavity occurred in rats given 20, 40, or 80 mg NDEA/kg body wt whereas the same cells were not necrotic in hamsters given NDEA. The results demonstrate the unique susceptibility of cells of the Bowman's glands to the toxic effects of NDEA given ip and indicate that nasal tissues of the rat are more susceptible to the necrogenic effects of NDEA than those of the hamster.

Sequential study on the synergistic effects of 2,2',4,4',5,5'-hexabromobiphenyl and 3,3',4,4',5,5'-hexabromobiphenyl on hepatic tumor promotion

A sequential study was completed to determine the effect of polybrominated biphenyl (PBB) congeners on the enhancement of gamma-glutamyl transpeptidase (GGT)-positive altered hepatic foci (AHF) and the development of hepatic nodules (HN) and carcinomas. Female Sprague-Dawley rats were given a single dose of N-nitrosodiethylamine (NDEA) 24 h following a 70% partial hepatectomy. Thirty days later, rats were randomly assigned to groups and fed a basal diet or the basal diet containing 10 p.p.m. 2,2',4,4',5,5'-hexabromobiphenyl (245-HBB), 0.1 p.p.m. 3,3',4,4',5,5'-hexabromobiphenyl (345-HBB) or 10 p.p.m. 245-HBB plus 0.1 p.p.m. 345-HBB for 140 days followed by a basal diet for up to another 310 days. Rats from each group were killed 170, 240 or 480 days after partial hepatectomy. Dietary exposure to 245-HBB and 245-HBB plus 345-HBB enhanced the development of AHF and HN whereas 345-HBB alone did not. The combination of 245-HBB and 345-HBB caused a synergistic effect on the development of AHF and HN. The number of hepatocellular carcinomas was low and evenly distributed among the groups of rats fed diets containing PBB.

The growth of children's moment of inertia

As children grow, their moments of inertia increase. The magnitude and timing of these changes can affect the rotations of the body. The present study evaluated inter-individual differences in the transverse centroidal moment of inertia for 12 boys between 5 and 16 yr, using intra-individual data from three successive years. Segmental masses and moments of inertia were estimated using the elliptical zone model and the model then repositioned into two configurations: a layout position from a back handspring and a tuck position from a back somersault. In each case, the mass centroid and the moment of inertia about the transverse axis were calculated. With growth indexed by age, it was shown that the rate of change increases with age. For the children 10 yr and younger, the rate of change of moment of inertia was approximately 30% of the rate for the older children. Also, at each age level, there was a wide range of moments of inertia. In order to improve the prediction of moment of inertia, height and mass were tried as predictors with a noticeable improvement in correlation and linearity. The best predictor, however, was found to be the product of mass and height squared (M X H2) with correlations of 0.99 and 0.97. It is suggested that, because of the effects of growth on the moment of inertia. M X H2 could be used in conjunction with age in order to better appreciate the potential effects of change of moment of inertia.

Body segment mass, radius and radius of gyration proportions of children

The segment inertial parameters of children are fundamental to the analysis and simulation of their movements. Generally it has been recognized that adult parameters cannot be extrapolated and most of the anthropometric data on children are of little or no use for determining inertias. Consequently, there have been few studies of children's kinetics. In response to this problem a longitudinal investigation, the Laurentian Study of Biomechanical Development, was launched and in this paper the effects of growth on selected segmental size and inertial parameters are reported for boys between the ages of 4 and 15 yr. The twelve subjects, representing heterogeneous body types were followed over 3 yr for a total of 36 observations. Elliptical zones 2 cm wide were used to model the body and segment inertias calculated using segment densities from the literature. These inertias were the mass, moment of inertia and mass centroid location for a fourteen segment planar representation of the body. The general accuracy mean error based on body mass was 0.203% which is consistent with reports from similar studies and techniques. Plots of segment mass proportions with respect to age showed a decrease in the head proportion balanced by increases in the thigh, shank, foot and upper arm proportions in particular. The trends for each segment were consistent with the trends for linear measures reported in the anthropometry literature. Radius proportions to the mass centroid and radius of gyration proportions were also plotted and showed smaller but consistent changes with respect to age. Linear regressions were then fitted to the distributions and standard errors calculated. The magnitude and slope of the regressions were for the most part consistent with a reported cross-sectional study of Japanese children. Where data were available, predicted parameters were compared with the reported parameters for a 12 yr old analyzed using a different mathematical model. Comparisons were also made between the predicted parameters at 15 yr and the reported parameters for healthy young adults who had been scanned using a gamma-radiation technique. For most parameters there was either good agreement or differences could be explained logically. The traditionally used parameters from older cadavers were quite inconsistent with the above. The variances of the 36 observations about the regression lines as indicated by the standard errors were small. As an illustration of the effect of these variances, the trunk parameters for a 10 yr old performing a standing jump for distance were decreased by 1 S.E. and this matched by increases for the thigh, shank and head.(ABSTRACT TRUNCATED AT 400 WORDS)

Chronic active hepatitis in 26 Doberman pinschers

Chronic active hepatitis with increased hepatic copper concentration was diagnosed in 25 female and 1 male Doberman Pinscher dogs. Common clinical signs included polyuria/polydipsia, weight loss, anorexia, icterus, and ascites. Increased liver enzyme activities and abnormal liver function test results were the most consistent clinicopathologic changes. The dogs were assigned to 3 groups on the basis of clinical course of the disease. Group 1 dogs (n = 12) had clinical signs of advanced liver failure and died within one week. Group 2 dogs (n = 7) had less severe clinical signs of liver disease and died within one month. Group 3 dogs (n = 5) did not have clinical signs of illness or had mild clinical signs of liver disease and died 1 to 42 months after initial evaluation. One dog could not be reevaluated and another dog was alive 3 months after initial examination. Treatments consisted of supportive care for dogs in group 1, and dietary manipulations and corticosteroids for dogs in groups 2 and 3. The association of increased liver copper concentration and chronic active hepatitis is not known.

A general Newtonian simulation of an n-segment open chain model

This paper presents a set of general Newtonian equations which govern the simulation of movement of a body represented by n open chain links. The input for the simulation consisted of the joint moment of force histories, lengths, masses and moments of inertia, the initial absolute angular displacements and velocities and, for the fixed or constrained axis of the nth segment, the acceleration history. Angular accelerations were then determined by solving n linear equations simultaneously, and angular velocities and displacements determined by integrating forwards. The final output was in the form of a graphical display of the linked figure. Applications of the simulation were demonstrated using three-segment representations of movements of the upper and lower extremities and a five-segment representation of a jump. Good agreement was achieved between the displayed angular displacements for the original and simulated movements. The potential for varying the input data has been examined and the implications of anticipating the effects of changed torques, inertial characteristics including attached prosthetic or sports implements and/or the initial conditions for a movement are discussed.

Effect of varying the length of exposure to polybrominated biphenyls on the development of gamma-glutamyl transpeptidase enzyme-altered foci

Female Sprague-Dawley rats were fed polybrominated biphenyls (PBBs) for 15 or 140 days after a 70% partial hepatectomy and diethylnitrosamine administration (10 mg/kg body weight) to determine the effect of varying the length of exposure to PBBs on the enhancement of gamma-glutamyl transpeptidase enzyme-altered foci. fireMaster BP-6R, a commercial mixture of PBBs, was fed to rats at a dietary concentration of 100 mg/kg for 15 days or 10 mg/kg for 140 days during the promotion phase of a two-stage hepatocarcinogenesis assay. Results indicate that short term exposure to PBBs is as effective as long term exposure in enhancing the development of enzyme-altered foci.

Hepatic tumor-promoting ability of 3,3',4,4',5,5'-hexabromobiphenyl: the interrelationship between toxicity, induction of hepatic microsomal drug metabolizing enzymes, and tumor-promoting ability

Female Sprague-Dawley rats were fed diets containing 0, 0.01, 0.1, or 1.0 mg/kg 3,3',4,4',5,5'-hexabromobiphenyl (345-HBB) for 140 days after a 70% partial hepatectomy and diethylnitrosamine administration (10 mg/kg body weight) to determine if 345-HBB had tumor-promoting ability in a two-stage hepatocarcinogenesis assay. Tumor-promoting ability was assessed by measuring enzyme-altered foci exhibiting gamma-glutamyl transpeptidase activity. Enhancement of enzyme-altered foci occurred only at a dietary concentration of 345-HBB (1.0 mg/kg) that was toxic. The toxic effects were decreased body weight gain, involution of the thymus, increased liver weight, histologic and ultrastructural alterations of the liver, and elevated serum concentrations of aspartate aminotransferase. 345-HBB is a strict 3-methylcholanthrene (MC) type of hepatic microsomal drug metabolizing enzyme inducer and caused a dose-related increase of cytochrome P-450. 345-HBB, at a dietary concentration of 0.1 mg/kg, caused a physiologic response in rats as determined by induction of hepatic microsomal drug metabolizing enzymes, but there was minimal evidence of toxicity and no evidence of tumor-promoting ability. Results indicate that there can be induction of MC type of hepatic microsomal drug-metabolizing enzymes without toxicity or tumor-promoting ability and that the tumor-promoting ability of 345-HBB was most likely the result of hepatic degeneration and necrosis. This finding is in contrast to previous studies in which a closely related congener, 2,2',4,4',5,5'-hexabromobiphenyl, enhanced the development of enzyme-altered foci at dietary concentrations that were not hepatotoxic.

Effect of combined antibiotic therapy on fertility in brood bitches infected with Brucella canis

Bitches with naturally occurring Brucella canis infection were treated with combined antibiotic therapy consisting of tetracycline, dihydrostreptomycin, and trimethoprim-sulfadiazine. After treatment, all but 1 bitch became abacteremic, and serologic titers declined for a variable length of time (3 months to 1 years). Abortion did not occur while these bitches were abacteremic. Although sequential antibiotic therapy for 6 weeks did not eradicate Brucella canis from affected bitches, it did not prevent abortion. The number of live pups whelped and weaned by treated bitches was comparable with that in bitches before they became infected.

Polybrominated biphenyls as promoters in experimental hepatocarcinogenesis in rats

Female Sprague Dawley rats were fed polybrominated biphenyls (PBB) for six months after a 70% partial hepatectomy and diethylnitrosamine administration (10 mg/kg body weight) to determine if PBB could serve as a tumor promoter in a two stage hepatocarcinogenesis test system. Firemaster BP-6, a commercial mixture of PBB, and its major congener, 2,2',4,4',5,5'-hexabromobiphenyl (HBB) were used in this study. Tumor promoting ability was assessed by measuring enzyme altered foci exhibiting gamma glutamyl transpeptidase activity. Dietary concentrations of 10 and 100 p.p.m. of the mixture of PBB and of HBB were found to be promoters of hepatocarcinogenesis. The mixture of PBB had a greater tumor promoting ability than HBB.

The effect of a 12-month growth period on the body moments of inertia of children

The effect of growth over a 12-month period on the principal moments of inertia for the body was investigated. The body was considered to be modelled as composed of elliptical zones 2 cm wide. Twelve children between the ages of 4 and 12 years and of different body types were tested and retested after 12 months. Moments of inertia for the three principal axes were calculated. A comparison of the results for the moment of inertia about the centroidal transverse axis showed increases from 12-57%. The results for the longitudinal centroidal axis ranged from 8-92%. For most of the children these percentage changes exceeded those in the traditional indicators of age, height, and mass. The product, mass times height squared (MH2), appeared to indicate the changes more accurately. Extreme changes were noted for a 12/13-year-old undergoing pubescent growth, a 6/7-year-old ectomorph, and a 4/5-year-old endomorph. It is suggested that the extreme changes, in particular, would make rotational movements difficult and there could be an extended adaptation period.