Muscle fibre size and type distribution in thoracic and lumbar regions of erector spinae in healthy subjects without low back pain: normal values and sex differences

This study sought to investigate the normal muscle fibre size and type distribution of the human erector spinae, both in thoracic and lumbar regions, in a group of 31 young healthy male (n = 17) and female (n = 14) volunteers. Two percutaneous muscle biopsy samples were obtained under local anaesthesia, from the belly of the left erector spinae, at the levels of the 10th thoracic and 3rd lumbar vertebrae. Samples were prepared for routine histochemistry for the identification of fibre types. Fibre size (cross-sectional area (CSA) and narrow diameter (ND)) was quantified using computerised image analysis. The mean CSA/ND for each fibre type was greater in the thoracic than the lumbar region, but there was no difference between the 2 regions either for percentage type I (i.e. percentage distribution by number), percentage type I area (i.e. relative area of the muscle occupied by type I fibres) or the ratio describing the size of the type I fibre relative to that of the type II. Men had larger fibres than women, for each fibre type and at both sampling sites. In the men, each fibre type was of a similar mean size, whereas in the women the type I fibres were considerably larger than both the type IIA and type IIB fibres, with no difference between the latter two. In both regions of the erector spinae there was no difference between men and women for the proportion (%) of a given fibre type, but the percentage type I fibre area was significantly higher in the women. The erector spinae display muscle fibre characteristics which are clearly very different from those of other skeletal muscles, and which, with their predominance of relatively large type I (slow twitch) fibres, befit their function as postural muscles. Differences between thoracic and lumbar fascicles of the muscle, and between the muscles of men and women, may reflect adaptive responses to differences in function. In assessing the degree of any pathological change in the muscle of patients with low back pain, it seems clear that (1) sex cannot be disregarded and (2) 'atrophied' (using the criteria from other muscles) type II fibres are not necessarily abnormal for the erector spinae, particularly in women.

Optimization of liposome mediated transfection of a neuronal cell line

A cell line derived from sensory neurons was transfected with high efficiency using cationic liposomes, formulated from 3 beta [N-(N',N'-dimethylaminoethane)carbamoyl]-cholesterol (DC-Chol) and dioleoyl L-alpha-phosphatidylethanolamine (DOPE). This is the first time that cationic liposomes of this type have been reported to transfect a neuronal cell line. We used a reporter gene construct expressing beta-galactosidase under the control of the cytomegalovirus immediate early promoter and routinely observed transfection efficiencies > 40%. Parameters affecting transfection efficiency were examined and the ratio of DNA to liposome proved to be crucial. Liposome formulation procedures and cell transfection protocols devised here will be used as a basis for further in vivo and in vitro work.

New products: benchmarking the critical success factors

New-product development is emerging as the key strategic endeavour of companies in fields such as medical devices. Drawing on the findings of a recent study, the author suggests that the critical factors that influence the success of new products are process, strategy and resources. Process was found to have the strongest impact on the performance of a new product. This article describes a stage-gate process that provides companies with a template for driving new-product projects from idea through to launch.

Herniated intervertebral disc-associated periradicular fibrosis and vascular abnormalities occur without inflammatory cell infiltration

STUDY DESIGN

Prospective histologic comparison of perineural tissues from patients requiring decompression surgery for herniated intervertebral disc with those from cadaveric controls.

OBJECTIVES

To examine the significance of herniated intervertebral-disc-associated perineural vascular and fibrotic abnormalities with respect to back pain symptom generation.

SUMMARY OF BACKGROUND DATA

Previous cadaveric studies have demonstrated perineural vascular congestion, dilatation, and thrombosis and perineural and intraneural fibrosis occurring in association with herniated intervertebral disc. It was suggested that these neural abnormalities were the result of ischemia, due to venous outflow obstruction, and also represented a possible cause of ongoing back pain symptoms. Criticisms of such a conclusion arose, however, because the possibility could not be excluded that these abnormalities were the result of postmortem artifact.

METHODS

Histologic and immunohistochemical comparison of discal and peridiscal tissues removed from 11 patients with radiographically proven herniated intervertebral disc requiring decompressive surgery and from 6 fresh cadavers without history of back pain in life.

RESULTS

Histology and immunohistochemistry of perineural and extraneural tissues from patients revealed vascular congestion, neovascularization, and endothelial abnormalities including luminal platelet adhesion, in association with reductions in von Willebrand factor levels, together with perivascular and perineural fibrosis. Elevated fibrogenic cytokine concentrations were also detected in patients' tissues. These changes occurred without evidence of inflammation and were absent in cadaveric control tissues.

CONCLUSIONS

The vascular abnormalities detected in patients may represent an important etiopathologic factor predisposing to intraneural and perineural fibrosis, and hence to chronic pain symptoms, after disc herniation. It seems important to preserve the perineural microcirculation following disc herniation.

Relative contributions of HLA-DQA and complement C4A loci in determining susceptibility to systemic lupus erythematosus

The objective of this study was to reassess the role of C4A null alleles in systemic lupus erythematosus (SLE) susceptibility after taking into account the association of DQA*0501 with this disease. The frequency of C4A null alleles in 82 SLE patients and 59 controls was determined using both immunofixation and a TaqI RFLP method. HLA-DQA and DQB alleles were identified by sequence-specific oligonucleotide typing. Empirical logistic analysis was used to assess the interactive effects of C4 and DQA alleles. It was found that the strongest association with SLE was for the combination of DQA*0501 and C4A*Q0 [odds ratio (OR) = 5.4, 95% confidence interval (CI) 2.5-11.7]. Both DQA*0501 (P = 0.02) and C4A*Q0 (P = 0.03) appeared to have significant individual effects on SLE susceptibility, with a significant statistical interaction between the two loci (P = 0.01). However, when anti-La antibody negative patients were examined only C4A*Q0 had a significant individual effect (P = 0.04). A significant statistical interaction between DQA*0501 and C4A*Q0 was again detected (P = 0.02). These results support the hypothesis that susceptibility to SLE is influenced by several genes with differing functions: HLA-DQA*0501 may predispose to autoantibody formation while C4A*Q0 impairs immune complex clearance.

Load-induced inflexion of the surface electromyographic signal during isometric fatiguing activity of normal human paraspinal muscle

In twelve normal subjects (aged 21-57 years) changes in surface electromyographic (EMG) activity of the paraspinal muscles were examined during "unloaded" and "weight-loaded" fatigue tests. These comprised 60 second isometric holds against gravity with the upper body unsupported in a horizontal and prone position while the lower body was firmly secured to a couch. During one of the tests sand bags, representing 10% of subjects' body weight, were placed between the scapulae. Integrated EMG (IEMG) and the frequency power spectrum were monitored throughout each test. During both tests IEMG activity initially increased and then plateaued in the unloaded test but decreased in the loaded test. Since frequency changes in the power spectrum were similar during both fatigue tests, IEMG reductions in the loaded test appeared due to reductions in motor unit recruitment. Despite these IEMG reductions the horizontal position was maintained, suggesting the operation of intrinsic peripheral fatigue resistance mechanisms which were utilised to a greater extent during the loaded test.

HLA-DP does not contribute towards susceptibility to systemic lupus erythematosus

OBJECTIVES

To determine whether HLA-DP genes are involved in determining susceptibility to systemic lupus erythematosus (SLE).

METHODS

HLA-DPA1 and DPB1 genes were amplified by PCR of DNA samples from a panel of patients with SLE and normal controls. Amplified DNA was blotted on to nylon filters and probed with sequence-specific oligonucleotide (SSO) probes.

RESULTS

No DPA1 or DPB1 allele was significantly associated with SLE, or with any immunological or clinical subset of SLE. Evidence was found for only limited linkage disequilibrium between HLA-DP and HLA-DQ/DR variants, and none between HLA-DP and the TAP2 gene.

CONCLUSIONS

These data indicate that HLA-DP genes do not contribute towards determining susceptibility to SLE.

Measuring outcomes in care of the elderly

This observational study was designed to assess whether routine measurement of outcomes using standard instruments is possible as part of clinical routine in care of the elderly, and to establish if such instruments are responsive to clinical change. Indices of functional status, cognitive function and subjective health status were collected routinely on admission and discharge in 540 inpatients and 340 patients attending a day hospital. Data collection became integrated into clinical routine. Response rates were generally good and yielded acceptably complete data. For inpatients, outcome was reflected by measurement of survival, physical function (Barthel index) and social status, each of these indicators showing significant change between admission and discharge. For day hospital patients, neither these, nor the Nottingham ADL scale, nor a health status indicator proved sufficiently responsive to clinical change to merit recommendation as outcome indicators for routine use in older patients. In ambulatory care in older patients, such as those attending a day hospital, new approaches are needed to measure clinical outcomes.

HLA-DQ, DR and complement C4 variants in systemic lupus erythematosus

We have defined HLA-DQA, DQB, DR and complement C4 variants in 92 subjects with SLE and 73 controls. Subjects with SLE showed an increased frequency of HLA-DQA*0501 (P < 0.01 corrected, odds ratio (OR) = 4.97; 95% C.I. = 2.52-9.81), DR3 (P < 0.001, OR = 3.18; 95% C.I. = 1.67-6.04) and C4A*Q0 (P < 0.05, OR = 1.91; 95% C.I. = 0.999-3.65) vs controls. These increases were particularly marked in those subjects positive for antibodies to both Ro and La. HLA-DQB*0501 (P < 0.01 corrected, OR = 0.03), DQA*0101 (P = 0.0012 uncorrected, OR = 0.23) and DR7 (P = 0.0018 uncorrected, OR = 0.28) were decreased in frequency in SLE. SLE patients with disease onset prior to age 30 yr were more likely to possess a DR3-bearing haplotype (P < 0.05 corrected) than those with onset after age 30 yr. No significant associations were found in patients with circulating antibodies to double-stranded DNA, Ro alone, U1 RNP, Sm or in those SLE patients with renal disease or vasculitis. The different associations found in different clinical and immunological subsets of SLE support the concept that SLE contains a variety of immunogenetic subgroups. Analysis of the associations between SLE and DR3, DQA*0501 and C4A*Q0 using the empirical logistic test suggests that the association of SLE with HLA-DQA*0501 is likely to be primary to the associations with both DR3 and C4A*Q0 (P < 0.001). Our results therefore raise the possibility that genes within the HLA-DQ region may have a direct effect upon susceptibility to SLE.

HLA associations in subjects with rheumatoid arthritis and bronchiectasis but not with other pulmonary complications of rheumatoid disease

We have examined HLA-DR, DQA and DQB variants in 72 controls, 153 subjects with RA without extra-articular features and in subjects with the rheumatoid pulmonary complications of interstitial fibrosis (23) peripheral airways disease (13) and in 41 subjects with RA and bronchiectasis. Subjects with RA alone showed the expected association with HLA-DR4 (79%) but those with RA and co-existent pulmonary fibrosis were less likely to be DR4 positive (61%). No other HLA-DR variants were significantly increased in the different disease groups. HLA-DQB1*0501 which types serologically as DQw1 was increased in subjects with RA and peripheral airways disease as compared to rheumatoid subjects with normal lung function, but these differences were not statistically significant. DQB1*0601 was increased in subjects with bronchiectasis with or without RA (but only significantly so in RA-BR subjects) DQB1*0301, DQB1*0201 and DQA1*0501 frequencies were also increased in subjects with RA and bronchiectasis as compared to those with RA alone.

Normal paraspinal muscle electromyographic fatigue characteristics in patients with primary fibromyalgia

Paraspinal muscle fatigue mechanisms were compared in 14 primary fibromyalgia patients and 14 age and sex matched normal subjects using a standardized 60-s isometric endurance test of the paraspinal muscles, during which surface integrated electromyographic (IEMG) activity was recorded. Fatigue-induced IEMG increases were similar for both groups during the initial 40 s (up to 112 +/- 20% and 111 +/- 6% of initial values in patients and normal subjects respectively). Thereafter, IEMG fell significantly in patients (P < 0.05) but only slightly in controls, so that at 58 s IEMG was 102 +/- 13% in patients and 109 +/- 12% in controls. If patients were divided according to body mass index (BMI, range 19-25 in controls) those with a BMI < 26 (n = 5) showed IEMG changes similar to those of control subjects throughout the test, while obese patients with BMI > 26 (n = 9) showed greater IEMG declines after 40 s than either normal subjects or in the fibromyalgia group as a whole. Paraspinal muscle fatigue mechanisms appear normal in primary fibromyalgia patients. Isometric force maintenance in overweight patients, despite IEMG declines, illustrates the action of intrinsic fatigue resistance mechanisms which were presumably utilized to a greater extent in these patients to cope with the extra load.

Increased central drive during fatiguing contractions of the paraspinal muscles in patients with chronic low back pain

In low back pain patients the paraspinal muscles demonstrate excess fatigability. Whether the cause is "central" as could result from impaired motor unit recruitment due to poor motivation or fear of pain, or "peripheral", and caused by defects in the contractile apparatus, is unknown. Using surface electromyography in conjunction with a standardized isometric fatigue test, this study investigates the mechanisms causing paraspinal muscle dysfunction in patients with both nonsurgical and postsurgical chronic low back pain. During the fatigue test normal subjects and both patient groups exhibited electromyographic increases. These were significantly greater in both patient groups, indicating increased central drive to their muscles. These findings may suggest that patients' excess fatigue is peripheral in origin, with increased central drive arising secondary to muscle wasting or denervation, although a central activation defect has not been excluded. Impaired physical performance in low back pain patients does not seem to be caused by lack of central drive.

Cytokine inter-relationships and their association with disease activity in arthritis

In order to investigate the relationships between cytokine production and arthritic disease we have determined the concentrations of immunoreactive interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-6, tumour necrosis factor-alpha (TNF-alpha), interferon-alpha (IFN-alpha), IFN-gamma, and soluble IL-2-receptor (sIL-2R), as well as bioactive IL-1 and IL-6, in synovial fluids (SF) and plasma of patients with a variety of arthritides. Careful assay revealed only minimal concentrations of IL-1, particularly its biologically active form, in SF. No IL-1 was detectable in the plasma of patients that had IL-1 in their SF. Concentrations of both immunoreactive IL-1 beta and TNF-alpha in SF of rheumatoid arthritis (RA) patients were significantly higher than those in SF from patients with other inflammatory arthritides or osteoarthritis (OA). IL-6 and sIL-2R concentrations in both SF and plasma were higher in RA patients than in OA patients, and were significantly correlated. Approximately half of the SF from patients with all arthropathies contained detectable IFN-alpha, whilst IFN-Y was present in less than 10%. There were significant associations between IL-6, sIL-2R, IL-1 beta, TNF-alpha and IFN-alpha. The concentration of these cytokines, where detectable, was also related to leukocyte counts in the SF, as well as to parameters assessing local and systemic disease activity. Although IL-6 was the cytokine most clearly related to other cytokines, and to parameters assessing disease activity, the relationship between general articular disease activity and IL-6 was only evident in patients with arthropathies other than rheumatoid arthritis.

Abnormal temperature control suggesting sympathetic dysfunction in the shoulder skin of patients with frozen shoulder

In view of the possibility that sympathetically mediated pain could be responsible for frozen shoulder symptoms we compared shoulder skin vasomotor control in 11 patients with frozen shoulder and 17 similarly aged normal subjects without shoulder pain. Using computer-assisted thermography the shoulder skin temperature was assessed before and following a 'cold challenge' which consisted of a 15 degrees C cold pack being held against the skin for 60 sec. Both prior to and immediately following the cold challenge shoulder skin temperatures tended to be lower in the patients. During a 10-min rewarming phase, however, the between-group temperature difference increased and became significant at the 0.05 level. These abnormalities of temperature control in patients clearly suggest sympathetic dysfunction in the dermatome subserving pain sensation from the affected shoulder. Whether these abnormalities are primary or secondary remains unresolved.

Radiographic demonstration of paraspinal muscle wasting in patients with chronic low back pain

This study investigated whether paraspinal muscle wasting occurs in association with chronic low back pain (LBP). Cross-sectional areas (CSA) of spinal and paraspinal structures were measured radiographically, at the level of L4, in 43 patients with recent and 44 with chronic LBP. Crude anthropometry demonstrated no differences between the groups with regard to L4 and paraspinal and psoas muscle CSAs, but inter-individual differences were large. Since body weight correlated significantly with L4 CSA this dimension was used as an 'internal standard' and further inter-individual comparisons were made using paraspinal: L4 and psoas: L4 (i.e. muscle to bone) CSA ratios. Muscle assessments made in this 'relative' fashion revealed significant reductions in paraspinal and psoas dimensions in patients with chronic compared to recent onset LBP. These changes could cause paraspinal and psoas muscle weakness and thereby predispose to spinal instability and progressive dysfunction.

Gender variation of human spinal and paraspinal structures

To investigate the effects of gender on the dimensions of spinal and paraspinal structures, anthropometric assessments were made on 92 patients (39 female and 53 male, aged 20-55 years) suffering low back pain which required computerized tomography for further investigation. During routine scans cross-sectional areas (CSA) of L4 and paraspinal and psoas muscles were measured at the level of the upper table of L4. The results indicated significantly greater cross-sectional areas of all structures in males who were significantly heavier. For both sexes there were significant, linear relationships between L4 and paraspinal and psoas muscle cross-sectional areas and bodyweight. Gender differences were apparent since for each structure regression lines were, although parallel, separated according to sex, with males having significantly greater muscle and bone cross-sectional areas than females. The gender difference between the lines was much greater for psoas than for paraspinal muscles, suggesting the influence of biomechanical, in addition to hormonal, differences between the sexes.

Inhibition by prostaglandin E1 and E2 of 1,25-dihydroxyvitamin D3 synthesis by synovial fluid macrophages from arthritic joints

Previous work has shown that renal metabolism of 25-dihydroxyvitamin D3 (25(OH)D3) to the active metabolite, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) is stimulated by prostaglandin E2 and inhibited by acetylsalicylate (aspirin). As prostaglandins are primary inflammatory mediators and synovial fluid macrophages are known to synthesise 1,25(OH)2D3 in vitro, the effects of prostaglandin E1, prostaglandin E2, and aspirin on the metabolism of 25(OH)D3 by cells cultured from synovial fluid of patients with inflammatory arthritis were investigated. Most cultures contained non-proliferating macrophages which formed 1,25(OH)2D3; however, two of 13 cultures contained colonies of rapidly proliferating fibroblast-like cells which formed 24,25(OH)2D3 (24,25(OH)2D3). Prostaglandin E1 and prostaglandin E2 (0.01-10 mumol/l) induced marked inhibition of 1,25(OH)2D3 synthesis (up to 94%) in a dose dependent manner after preincubations of 24 hours but not over straightforward six hour incubations. Exposure of macrophages to aspirin (1 mumol/l-1 mmol/l) for 24 hours did not affect 1,25(OH)2D3 synthesis unless the cells had been pretreated with lipopolysaccharides, in which instance 1 mM aspirin increased 1,25(OH)2D3 synthesis. Lipopolysaccharide is a macrophage activating factor which stimulates macrophages to form 1,25(OH)2D3, and it also induces prostaglandin synthesis which would be inhibited by aspirin. Taken together these results suggest that prostaglandin E1 and prostaglandin E2 synthesised by macrophages may act in an autocrine manner to attenuate the ability of macrophage activating factors, such as lipopolysaccharide, to stimulate 1,25(OH)2D3 synthesis. Prostaglandins synthesised by other inflammatory cells may also inhibit 1,25(OH)2D3 synthesis in a paracrine manner. In contrast, prostaglandin E2 and aspirin had limited effects on fibroblast 24,25(OH)2D3 synthesis. This study shows that the effects of prostaglandin E1, prostaglandin E2, and aspirin in macrophages contrast with those previously reported for the renal 25(OH)D3-1alpha-hydroxylase, where prostaglandin E2 stimulated and aspirin inhibited enzyme activity. These results further emphasise that synthesis of 1,25(OH)2D3 in non-renal sites is independently regulated, which is consistent with it having an immunological role at a local level rather than playing a part in systemic calcium homeostasis.

Muscle sounds during voluntary and stimulated contractions of the human adductor pollicis muscle

The relationships between force, electromyography (EMG), and muscle sounds recorded by acoustic myography (AMG) were investigated for both voluntary and stimulated isometric contractions in the adductor pollicis muscle. Voluntary activity was performed at 10, 25, 50, 75, 85, and 100% of maximal voluntary contraction (MVC) force. Stimulated contractions were produced by supramaximal electrical stimulation of the ulnar nerve at the wrist at frequencies of 10, 20, 30, 50, 70, and 100 Hz. Contractions lasted for 4 s each, and were performed in random order with a 3-min rest between each. The voluntary and stimulation studies were performed in random order between subjects. Simultaneous recordings were obtained for force, force oscillation (from the differentiated force signal), and raw and integrated AMG (IAMG) and EMG (IEMG). During voluntary contractions, IAMG increased with force up to MVC (r2 = 0.99, P less than 0.001) in a curvilinear fashion and a similar relationship was seen between force and IEMG (r2 = 0.99, P less than 0.001). Conversely, during stimulated contractions as stimulation frequency increased, IAMG decreased in a fashion mirroring the frequency-force curve. The frequency of the AMG signal matched stimulation frequency and declines in total IAMG were due to reductions in amplitude of the AMG signal. The stimulation frequency-oscillation of force relationship was identical to that seen for stimulation frequency and IAMG. Integrated EMG increased linearly with stimulation frequency (r = 0.99). The stimulation results suggest that muscle sounds reflect oscillation of muscle fibers and that AMG signal characteristics are determined by motor control mechanisms rather than intrinsic contractile processes.

Bone abnormalities and severe arthritis in pachydermoperiostosis

Two patients with pachydermoperiostosis were studied in whom the predominant features at presentation were severe and disabling knee and ankle joint pain in association with distal long bone pain. Analysis of synovial fluid from the knee joints showed non-inflammatory changes. In one patient a bicortical iliac crest bone biopsy specimen, taken after labelling with demeclocycline, showed appositional rates which were increased in cortical bone but reduced in trabecular bone. This mismatching resulted in trabecular osteoporosis, which occurred in association with increased numbers of osteoclasts, findings which suggest differential functional changes affecting the two bony envelopes.

Differential metabolism of 25-hydroxyvitamin D3 by cultured synovial fluid macrophages and fibroblast-like cells from patients with arthritis

Differential metabolism of 25-hydroxyvitamin D3 (25(OH)D3) has been shown for macrophages and fibroblast-like cells (possibly synoviocytes) cultured for two to 50 days after isolation from the synovial fluid of 12 patients with various forms of inflammatory arthritis. Macrophages synthesised the active metabolite of vitamin D3, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the synthesis of which was increased by bacterial lipopolysaccharide, a known macrophage activating factor. In contrast, fibroblast-like cells formed 24, 25-dihydroxyvitamin D3 (24,25(OH)2D3), synthesis of which was stimulated by 1,25(OH)2D3 and inhibited by lipopolysaccharide. The synthesis of 1,25(OH)2D3 and 24,25(OH)2D3 by macrophages and fibroblast-like cells respectively was inhibited by ketoconazole, indicating that both hydroxylases are dependent on cytochrome P-450. Mean (SEM) synovial fluid and serum 25(OH)D3 concentrations were 16.7 (1.7) and 22.2 (2.6) ng/ml and those of 1,25(OH)2D3 were 29.4 (4.8) and 43.3 (4.0) pg/ml respectively. In most cases concentrations were lower in synovial fluid than in paired serum samples, but in two patients 1,25(OH)2D3 concentrations were greater in synovial fluid than in serum, suggesting local synthesis within the affected joints.

Electro and acoustic myography for noninvasive assessment of lumbar paraspinal muscle function

In 31 normal subjects (17 male), aged 19-48 years, and 8 patients with chronic low back pain (4 male), aged 37-55 years, the repeatability of surface recordings of acoustic myography (AMG) and electromyography (EMG) were examined in the lumbar paraspinal muscles. Five isometric test positions were examined. In 21 of the normal subjects, four positions tested were: quiet standing, half extension from prone lying, full extension from prone with and without resistance. In 10 of the normal subjects and the 8 back pain patients, a standardised, unsupported horizontal position with the upper body over the end of a couch was tested. The AMG and EMG signals were full-wave rectified and integrated (iAMG and iEMG). The variability of recordings during repeated 5-s isometric contractions was assessed by analysis of variance (ANOVA) and the coefficient of variation (CV) was calculated from the ANOVA. Both recording techniques produced the most repeatable results during the unsupported, horizontal hold position. In the normal subjects, CV were, iAMG 5.6%, iEMG 4.9%; and in the patients, iAMG 4.4%, iEMG 2.6%. The CV for the other four isometric test positions ranged from 15.3% to 29.4% for iAMG, and 8% to 15.7% for iEMG. These results demonstrated that a controlled test manoeuvre for examining AMG and EMG of the paraspinal muscles was vital for repeatable recordings. The CV for the standardised, horizontal position were lower than for previously published results.(ABSTRACT TRUNCATED AT 250 WORDS)

Paraspinal muscle fibrosis: a specific pathological component in ankylosing spondylitis

The histological appearance of percutaneous superficial paraspinal muscle biopsy specimens from eight patients with ankylosing spondylitis was compared with that of biopsy specimens from 13 control patients with similar degrees of disability and spinal immobility due to severe, chronic mechanical back pain. In both groups marked type II muscle fibre atrophy was shown. Additionally, in patients with ankylosing spondylitis there were obvious increases in perifibre connective tissue in association with central migration of cell nuclei but without evidence of inflammation. Qualitative electromyography failed to show denervation changes in either group. Paraspinal muscle fibrosis, occurring over and above atrophic changes due to disuse, seems to be a specific pathological component of ankylosing spondylitis which may be of particular importance in early disease as it may contribute towards back stiffness and weakness.

Relationships between local inflammation, interleukin-6 concentration and the acute phase protein response in arthritis patients

Interleukin-6 (IL-6) concentrations in knee joint synovial fluids and paired plasma samples of arthritis patients were examined with respect to each other and parameters of the inflammatory response. Synovial fluid and plasma IL-6 concentrations were significantly higher in patients with inflammatory arthritis than those detected in patients with osteoarthritis (P less than 0.001). The IL-6 concentrations in synovial fluids were considerably higher than, but significantly correlated with (r = 0.65; P less than 0.001), those of plasma. Furthermore, synovial fluid IL-6 concentrations in bilaterally inflamed knees were significantly correlated (r = 0.79; P less than 0.001) and there was a significant correlation with the extent of inflammatory cell infiltrate (r = 0.75; P less than 0.001). In unselected rheumatoid arthritis patients there was only a weak correlation between IL-6 and plasma C-reactive protein (CRP) concentration, and no correlation between IL-6 and erythrocyte sedimentation rate (ESR). However, both ESR and CRP concentration were highly correlated with plasma IL-6 concentration in patients with other inflammatory arthritides, particularly psoriatic and HLA B27 positive spondyloarthritis (r = 0.72-0.94; P less than 0.005). These relationships suggest that IL-6 production in inflammed knee joints can be a significant determinant of acute phase protein responses in arthritis patients, although the situation in patients with rheumatoid arthritis is more complex and may be influenced by other disease-related factors.

The role of epidural fibrosis and defective fibrinolysis in the persistence of postlaminectomy back pain

Clinical features, contrast-enhanced lumbar tomographic findings, and biochemical plasma fibrinolytic parameters were critically assessed in 70 patients suffering severe, chronic postsurgical low-back and radicular pain to determine the cause of their persisting symptoms. Patients exhibited gross functional disability and significant impairment of plasma fibrinolytic activity, compared with 84 normal control subjects. This fibrinolytic defect appeared attributable to disproportionate increases in circulating plasminogen activator inhibitor-1 levels. Clinical features were slightly worse in patients with radiologic epidural fibrosis, whereas the frequency of radiologic abnormalities, including epidural fibrosis, was higher in patients with fibrinolytic abnormalities. The results, however, demonstrated no significant associations between patients' symptoms and signs and their biochemical and radiologic abnormalities.

Elevated endothelial-cell-stimulating angiogenic factor activity in rodent glycolytic skeletal muscles

1. Capillary density is greater in skeletal muscles comprised of predominantly oxidative (type I) fibres than in those comprised of mainly glycolytic (type II) fibres. In order to investigate further the angiogenic mechanisms involved in muscle capillarization, endothelial-cell-stimulating angiogenic factor activities in various rodent skeletal muscles were compared. 2. Eleven untrained adult male Wistar rats were killed and the predominantly oxidative (type I) muscle,s soleus and heart, the predominantly glycolytic (type II) muscle, extensor digitorum longus, and the mixed-fibre muscle, gastrocnemius, were removed. Each sample was separately homogenized and centrifuged and the supernatants were diafiltered to isolate the low-molecular-mass fraction containing endothelial-cell-stimulating angiogenic activity. This was assayed for its ability to activate latent collagenase and was expressed as units, where 1 unit represents the percentage activation of the enzyme h-1 (mg of protein in the supernatant)-1. 3. The results (medians and ranges) demonstrated significantly greater endothelial-cell-stimulating angiogenic factor activity in extensor digitorum longus muscle (2.14 units, 0.62-2.87 units, n = 13) than in soleus (0.82 units, 0.59-1.79 units, n = 15), gastrocnemius (0.34 units, 0.28-0.40 units, n = 4) or heart (0.43 units, 0.16-0.52 units, n = 11) (P less than 0.01 for each) muscle. 4. These findings suggest that endothelial-cell-stimulating angiogenic activity in muscle is either inversely or not related to the local capillary density, which may be at or near a maximum in physiologically contracting, predominantly oxidative muscles.

Fibrinolytic enhancement with stanozolol fails to improve symptoms and signs in patients with post-surgical back pain

An open trial with the fibrinolytic enchancing agent stanozolol was completed by eighteen patients (14 male) with severe back and radicular pain, despite previous lumbar surgery for prolapsed intervertebral disc. Assessments of their pain, disability and plasma fibrinolytic activity were undertaken before and after 12 or 24 months of therapy. Prior to treatment patients exhibited significant fibrinolytic abnormalities when compared with 84 normal controls; euglobulin clot lysis time (ELT) 442 vs 157 mins and fibrin plate lysis area (FPLA) 61 vs 113 mm2 respectively (p less than 0.01 for both). Stanozolol therapy normalised patients' fibrinolytic activity within three months. Disappointingly there were no concomitant clinical improvements in spinal pain or mobility despite 12 or 24 months of treatment. These results may indicate that perineural fibrosis, once formed, is not amenable to such therapy.

DNA variants of alpha-1-antitrypsin in rheumatoid arthritis with and without pulmonary complications

Restriction fragment length polymorphisms (RFLPs) of alpha-1-antitrypsin were studied in 99 subjects with rheumatoid arthritis alone, 21 subjects with rheumatoid arthritis and pulmonary fibrosis, 26 subjects with rheumatoid arthritis and bronchiectasis, and 86 controls. No associations with either rheumatoid arthritis itself or with the associated pulmonary disorders were noted in this U.K. Caucasoid population.

The development of structural complexity in the child's concept of family: the effect of cognitive stage, sex, and intactness of family

Twenty-eight boys and 28 girls at each of the Piagetian preoperational, concrete operational, and formal operational cognitive stages were given an interview focusing on their concepts of family. Half of each group were from intact families, and half were from divorced families. Interviews were scored for two structural aspects of the concept of family: conceptual level, and use of dimensions that structure the concept. The complexity of children's concepts was strongly related to cognitive stage and, to a lesser degree, to sex. Frequency of use of concept dimensions was strongly affected by general developmental level, though not specifically cognitive stage, and by intactness of family, but to a lesser degree by sex. Specific information is provided on the effect of these factors on perceptions of family composition, parental roles, and breadth of family activities.

Effect of low frequency fatigue on human muscle strength and fatigability during subsequent stimulated activity

Fatiguing contractions of the adductor pollicis muscle were produced by intermittent supramaximal stimulation of the ulnar nerve in a set frequency pattern, in six normal subjects. At the end of an initial fatiguing contraction series, low frequency fatigue (LFF) had been induced and persisted at 15 min of recovery. Stimulated fatiguing activity was then repeated in an identical fashion to the initial series. At high frequencies, declines in force were similar for both series. At low frequencies, declines in force were greater during the second series despite similar changes in compound muscle action potential amplitude. This confirmation that LFF persists during subsequent stimulated activity, and reduces low but not high frequency fatigue resistance, suggests that the impaired endurance of fatigued muscle during voluntary activity primarily results from peripheral changes at low frequency. These findings also have implications for therapeutic electrical stimulation of muscle.

Myofibrillar activation failure in McArdle's disease

Contractile properties of the adductor pollicis muscle were examined in 9 normal volunteers and 7 patients with histochemically proven myophosphorylase deficiency (McArdle's disease). Fatiguing contractions were produced by supramaximal stimulation of the ulnar nerve, delivered over a range of frequencies, to allow further examination of the mechanisms responsible for the premature fatigue in patients. The excessive reductions in force, demonstrated in patients at all frequencies, were not associated at high frequencies (50 and 100 Hz) with excessive declines in excitation (measured as compound muscle action potential). These results demonstrate that, in patients, myofibrillar activation failure occurs over and above that due to excitation failure. Abnormal slowing of relaxation mechanisms was also confirmed. These findings appear consistent with the hypothesis of inhibition of various ATPases by metabolic products. The observed, clear differences between normal subjects and myophosphorylase-deficient patients constitute the basis of an objective screening procedure for this and other glycolytic disorders.

Evaluating clinical competence with the new Fieldwork Evaluation

The new Fieldwork Evaluation for the Occupational Therapist has been developed and tested through a series of field tests. With use, careful attention to issues arising from its application, and additional research, the Fieldwork Evaluation can be retained and updated to meet changes in clinical education and evaluation procedures.

Mechanisms resisting fatigue in isometrically contracting human skeletal muscle

Human adductor pollicis was fatigued during circulatory occlusion by supramaximal stimulation via the ulnar nerve using intermittent trains of stimuli in ascending (1, 10, 20, 50 and 100 Hz) and descending (100, 50, 20, 10 and 1 Hz) frequencies to investigate the contribution of relaxation rate slowing and post-tetanic potentiation (PTP) to fatigue resistance. At 50 and 100 Hz force was initially well maintained despite a marked loss of excitation as indicated by EMG, demonstrating the operation of a high-frequency 'safety factor' which appeared independent of the pattern of stimulation. At 10 Hz, force was initially potentiated before declining during both activity series. Potentiation was greater during the descending frequency series and the rate of decline of force, or fatigability, was reduced. The 'extra' low-frequency potentiation at 10 Hz was not simply the result of PTP of twitch force, since this declined more during the descending than during the ascending series, nor the result of maximal relaxation rate changes which were identical for both fatiguing series. It is hypothesized that the extra potentiation and reduced fatigability at low stimulation frequencies, when preceded by high frequency, is the result of increased myofibrillar Ca2+ availability and/or sensitivity. These findings may have important practical implications in relation to functional electrical stimulation techniques as used in paraplegia and in other areas of muscle research where fatigue is to be minimized.

Normal muscle strength and fatigability in patients with effort syndromes

To examine fatigue mechanisms in an unselected series of patients with excess fatigue ("effort syndromes") their muscle function was compared with that of normal subjects. Voluntary performance was assessed with a cycle ergometer to exhaustion and by maximal isometric contractions of the quadriceps femoris. The mean maximal heart rate in patients during ergometry was 89% of the predicted rate, and quadriceps strength was either normal or was inappropriate for the available muscle, which suggested submaximal effort. Contractile performance was examined in the absence of volition with stimulated contractions of the adductor pollicis. During stimulated fatiguing activity patients were neither weaker nor more fatigable than controls; thus the excess fatigue experienced by the patients was not due to a defect of the contractile apparatus. The increased perception of effort must therefore be due to impairment of central rather than peripheral mechanisms. The optimal approach to treatment of effort syndromes combines physical and psychological techniques.

Physiological characterisation of the "warm up" effect of activity in patients with myotonic dystrophy

Contractile properties of adductor pollicis muscle were examined over a range of stimulation frequencies in patients with myotonic dystrophy and normal subjects. In patients, fresh muscle demonstrated impaired relaxation, weakness at all frequencies and selective loss of force and excitation at high frequencies. During stimulated "fatiguing" activity, patients showed improvements in force and relaxation which appeared to result from normalisation of membrane excitation. Normal twitch potentiation also occurred during activity suggesting intact excitation-contraction coupling. These electrophysiological findings help to characterise and explain the "warm up" effect described by patients.

Technique for physiological examination of canine skeletal muscle in vivo

A technique is described for studying the physiological function of canine skeletal muscle in vivo. The contractile properties of the tarsal flexor muscles were examined in three beagle dogs under general anaesthesia. The force responses to electrical stimulation of the common peroneal nerve were measured at various frequencies to determine the frequency:force relationship for this muscle group. Fatigue characteristics were also examined during intermittent stimulated activity delivered in a set pattern of frequencies. The results provide quantitative characterisation of muscle function which is repeatable. The technique described could be applied to other animals and is a potentially powerful tool for evaluating the effects of drugs on muscle performance.

Adjuvant chemotherapy for breast cancer: 20 years experience using CVFMP chemotherapy

In late 1963, we embarked on a program that combined oral prednisone and oral cyclophosphamide (Cytoxan) with intravenous (IV) vincristine, fluorouracil, and methotrexate (CVFMP). The initial 60 patients had an 80% response. Since then, a multitude of different combinations and variations in drug dosage and timing have been used. Basically, patient responses have improved from single-agent remissions of 15% to 30%, which lasted only 3 to 4 months to remissions now achieved in as many as 80% of patients which last for more than 1 year. We initiated a pilot study of adjuvant CVFMP therapy in 100 women who had four or more positive nodes at original mastectomy. Chemotherapy alone was used in 73 patients, while 27 received radiotherapy and then chemotherapy. Chemotherapy consisted of oral doses of prednisone, 0.75 mg/kg/d, in three divided doses. This was reduced weekly by 50% and discontinued in the majority of patients. Cyclophosphamide, 2 mg/kg/d, was administered orally in two or three divided doses. Both methotrexate, 0.6 to 0.7 mg/kg, and 5-fluorouracil, 12 mg/kg, were administered IV once a week. Vincristine, at a dose of 25 micrograms/kg was administered IV once a week for 5 weeks or until significant neurologic defect was noted. Of the 73 patients who received only chemotherapy, 19 relapsed; 80% of those 73 patients were disease free at 14 years. Of the 27 patients who received radiotherapy before CVFMP, 23 relapsed; less than 10% were disease free at 13 years.

The enterohepatic circulation of perhexiline metabolites in the male Wistar rat

1. The biliary excretion of some perhexiline metabolites has been assessed in male Wistar rats with biliary cannulation. 2. After intragastric administration of perhexiline maleate (2 mg/kg body weight) multiple perhexiline metabolites were detected in bile. 3. When aliquots of this metabolite-laden bile were administered intraduoduodenally to further 'recipient' rats with biliary cannulation, similar metabolites were detected in the bile of these rats, but at reduced concentrations equivalent to 30-35% of those present in the bile of 'donor' rats. 4. These findings indicate that in the male Wistar rat, there may be substantial enterohepatic circulation of some perhexiline metabolites.

Absence of excess peripheral muscle fatigue during beta-adrenoceptor blockade

1. In eight normal volunteers, the adductor pollicis (AP) was fatigued using intermittent trains of programmed, supramaximal stimulation at 1, 10, 20, 50, 100 and 1 Hz. Activity protocols were performed both with and without circulatory occlusion, both without and during propranolol 80 mg thrice daily in order to investigate the effects of beta-adrenoceptor blockade on 'peripheral' fatigue mechanisms. 2. The degree of beta-adrenoceptor blockade was assessed by the reduction of exercise tachycardia during cycle ergometry, e.g. pulse rates at 210 watts were reduced from 190 +/- 15 to 127 +/- 5 beats min-1 (mean +/- 1 s.d.) indicating that beta-adrenoceptor blockade was substantial and highly significant (P less than 0.001). 3. Before, during and following fatiguing activity with circulatory occlusion force declines were identical during and without beta-adrenoceptor blockade. During and following activity without occlusion, there were slight declines in force which were questionably significantly different at 20 Hz (P less than 0.05). 4. The compound muscle action potential (CMAP) amplitude, measured from the skin surface over the muscle, was unaltered by beta-adrenoceptor blockade before, during or after activity whether with or without circulatory occlusion. 5. The maximal relaxation rate (MRR) was not significantly reduced in previously unfatigued muscle during beta-adrenoceptor blockade. During activity, both with and without circulatory occlusion, there was no evidence that MRR was reduced significantly more during beta-adrenoceptor blockade. 6. The absence of a convincing effect of beta-adrenoceptor blockade on peripheral fatigue mechanisms may indicate that central mechanisms are involved or that impairments of peripheral force production, of a specific nature or as a result of exacerbation of limitations of circulatory oxygen transport, though small are detected during voluntary exercise and give rise to increases in motor unit recruitment and/or firing rates, and hence increased perception of fatigue.

Human muscle fatigue: frequency dependence of excitation and force generation

1. Human adductor pollicis was fatigued using intermittent trains of programmed stimulation at 1, 10, 20, 50, 100 and 1 Hz, during activity with and without circulatory occlusion, to investigate the relationships between force generation, excitation and maximal relaxation rate (MRR). 2. The relationship between force generation and excitation was markedly dependent on stimulation frequency. Force loss was greatest at low frequencies, with little reduction in excitation, but as frequency increased force was well maintained despite marked loss of excitation. 3. Changes in MRR during activity and recovery were independent of stimulation frequency. 4. Marked increases of force at 1 Hz (pre-tetanic) and 10 Hz occurred, with little reduction in excitation, during activity with and without circulatory occlusion. This may be due to post-tetanic potentiation in addition to slowing of relaxation (MRR). 5. At high frequency a 'safety factor' may thus operate to maintain force, despite obvious loss of excitation, while at low frequencies there may be marked potentiation of force, despite unchanged excitation. These mechanisms could permit resistance to fatigue with muscle function remaining optimal over a range of conditions.

Studies on the metabolism of perhexiline in man

We have studied the disposition of perhexiline and its two major metabolites, M1 and M3, in healthy volunteers and in patients with biliary T-tube drains after cholecystectomy. In healthy volunteers the genetic control for impaired hepatic oxidation is identical for debrisoquine, sparteine, and perhexiline. Poor metabolizers demonstrate markedly reduced production and excretion of the major metabolite, M1. Their production of M3 is also reduced, but to a lesser degree than for M1, confirming substrate stereoselectivity by hepatic oxidases. Biphasic urinary elimination of M1 and M3 is seen in intact extensive oxidizers, whereas only the first phase is apparent in patients with biliary T-tube drainage. This suggests the possibility of enterohepatic recycling of these compounds, which may account for their prolonged elimination. More than 90% of an ingested dose of perhexiline maleate remains unaccounted for at 24 h after ingestion, even in extensive metabolizers. A careful, radiolabelled tissue-distribution study is warranted to elucidate the complicated metabolic fate of perhexiline.

Simultaneous determination of perhexiline and its monohydroxy metabolites in biological fluids by gas chromatography-electron-capture detection

A rapid and sensitive method for the simultaneous determination of perhexiline and its cis-4-axial and trans-4-equatorial monohydroxy metabolites (M1 and M3, respectively) in human plasma, urine and bile is described. The assay utilises a single diethyl ether extraction, heptafluorobutyric acid anhydride derivatisation and separation and detection by gas chromatography-electron-capture detection. The limits of detection are 0.1 microgram/ml for perhexiline and 0.025 microgram/ml for the M1 and M3 metabolites. This method has been used in a five-day kinetic study of three healthy adult males who ingested a single 300-mg dose of perhexiline maleate. One of these volunteer subjects exhibited elevated plasma perhexiline and markedly reduced plasma and urinary M1 concentrations together with profoundly prolonged plasma and urinary M1 elimination times when compared with the other two subjects. These differences are thought to be of genetic origin. There were also obvious differences in urinary M3 concentrations which were discussed.

Aspiration of oral contents in Parkinson's disease. A case report

A patient with Parkinson's disease developed a non-ketotic hyperosmolar diabetic coma precipitated by chest infection. Initial improvement from treatment with intravenous insulin, ampicillin and fluid therapies was followed by severe deterioration and hypovolaemic shock. Further improvement occurred only when therapy directed against Gram-negative sepsis was added. A barium examination later demonstrated aspiration of oral contents with pulmonary soilage. The differences between the easily recognized early fulminating 'aspiration syndrome' caused by aspiration of gastric contents of low pH and the aspiration of oral contents, which may remain occult for many hours, is highlighted. Life-threatening Gram-negative or anaerobic infection may then occur but remain undiagnosed because the original aspiration of foreign material is unsuspected.

Acid and gastrin responses during intragastric titration in normal subjects and duodenal ulcer patients with G-cell hyperfunction

Amino acid induced acid and gastrin responses during intragastric titration at pH 2.5 and 5.5 were compared in normal subjects and duodenal ulcer patients with G-cell hyperfunction. The latter were identified on the basis of raised basal or maximal acid outputs and increased gastrin responses to feeding. In normal subjects the mixed amino acid meal stimulated only modest increases in serum gastrin, and the highest observed increase was about 30% that after a standard meal. In contrast, in the G-cell hyperfunction group the highest gastrin concentrations were similar to those after a standard meal. In the G-cell hyperfunction group the increment in serum gastrin at pH 2.5 expressed as a proportion of that at pH 5.5 was 0.29 indicating that the capacity of acid to inhibit gastrin release was well established in these patients. Acid secretory rates were close to maximal at both pH 2.5 and 5.5 during intragastric titration in the ulcer patients, but in normal subjects acid output was about 50% maximal at 2.5 and close to maximal at 5.5. The results suggest that the enhanced gastrin response to feeding in G-cell hyperfunction patients is because of increased sensitivity to amino acid stimulation rather than to diminished acid-inhibitory mechanisms.