Ambulatory transcutaneous carbon dioxide monitoring for children with neuromuscular disease.

OBJECTIVE: Early screening and diagnosis of nocturnal hypoventilation can slow progression to diurnal hypercapnia and mortality in children with neuromuscular disease (NMD). However, gold standard, laboratory-based polysomnography (PSG) testing is a limited resource. Therefore, we evaluated the diagnostic accuracy of ambulatory transcutaneous carbon dioxide (tcCO2) monitoring used in the home compared to PSG in children with NMD. METHODS: Prospective, cross-sectional study in children 0-18 years old with a confirmed diagnosis of NMD and a clinically indicated need for PSG. Ambulatory tcCO2 was assessed by a respiratory therapist in participant's homes. Demographics, and PSG (including tcCO2). RESULTS: We enrolled 39 children with NMD; 3 had unusable ambulatory tcCO2 data because of failure of drift correction on the machine (n = 2) or an air bubble (n = 1). The remaining 36 patients aged 11 months to 16 years (median (IQR) 12.5 years (6.0-15.8)) had ambulatory tcCO2 and outpatient level 1 PSG data. Ambulatory tcCO2 monitoring had a sensitivity of 20.0% (95% confidence interval [CI] 0.5-71.6%) and a specificity of 93.5% (95% CI 78.6-99.2%). Almost all children and/or parents (34/36, 94%) preferred ambulatory monitoring over in-hospital PSG. CONCLUSIONS: Ambulatory transcutaneous carbon dioxide monitoring was not sufficiently accurate as a clinical tool for the diagnosis of nocturnal hypoventilation our cohort of children with neuromuscular disease despite being preferred over PSG by both children and parents.

The Canadian Neuromuscular Disease Registry 2010-2019: A Decade of Facilitating Clinical Research Througha Nationwide, Pan-NeuromuscularDisease Registry.

We report the recruitment activities and outcomes of a multi-disease neuromuscular patient registry in Canada. The Canadian Neuromuscular Disease Registry (CNDR) registers individuals across Canada with a confirmed diagnosis of a neuromuscular disease. Diagnosis and contact information are collected across all diseases and detailed prospective data is collected for 5 specific diseases: Amyotrophic Lateral Sclerosis (ALS), Duchenne Muscular Dystrophy (DMD), Myotonic Dystrophy (DM), Limb Girdle Muscular Dystrophy (LGMD), and Spinal Muscular Atrophy (SMA). Since 2010, the CNDR has registered 4306 patients (1154 pediatric and 3148 adult) with 91 different neuromuscular diagnoses and has facilitated 125 projects (73 academic, 3 not-for-profit, 3 government, and 46 commercial) using registry data. In conclusion, the CNDR is an effective and productive pan-neuromuscular registry that has successfully facilitated a substantial number of studies over the past 10 years.

Enhancing human aspects of care with young people with muscular dystrophy: Results from a participatory qualitative study with clinicians.

BACKGROUND: Most research into clinical care of Duchenne or Becker dystrophinopathies (MD) has focused on slowing progressive muscular weakness and extending lifespan. Scarce attention has been paid to the "human" aspects of care such as psychosocial health, living a fulfilling life, or dealing with disability stigma. This study partnered with clinicians to identify and address local and systemic barriers to these human aspects of care. METHODS: We employed a participatory qualitative design at a multidisciplinary MD clinic using 2 methods: (a) ethnographic observations over a 6-month period of clinic visits of children with MD and families, involving 12 clinicians, and (b) 3 "dialogues" (2-way discussions) with these clinicians to collaboratively analyze practices and co-produce recommendations for change. RESULTS: Our methods produced rich data that, when coanalyzed with clinicians and in consultation with a family advisor, provided deep insights into the practices and underlying assumptions of a neuromuscular clinic. Staff recognized the importance of the human aspects of care but, in reviewing the observational data, identified that it was given insufficient attention in (a) routine clinical processes, (b) clinician-family patterns of interaction, and (c) staffing allocations. CONCLUSION: Although the human aspects of care were important to clinicians in the MD clinic, the routines and nature of the clinic meant these were frequently sidelined for biomedical objectives. We present collaboratively produced practical recommendations toward addressing this disjunction between ideals and practice including developing flexibility to tailor appointment frequency, composition, and length; providing time and physical space for psychosocial aspects of care; and clinician skill building to support child/family expression of "negative" emotions; and discussion of sociopolitical aspects of MD such as living with disability stigma. The study offers a set of considerations that, taking into account individual differences, offer insights for similar clinics elsewhere.

Bone health in boys with Duchenne Muscular Dystrophy on long-term daily deflazacort therapy.

Quality of life in Duchenne Muscular Dystrophy (DMD) has improved significantly with corticosteroid treatment. However, corticosteroids decrease bone mass and increase vertebral fragility fracture risk. We report on bone health in 39 boys with DMD on long-term deflazacort (0.9 mg/kg/day) therapy. Bone health was defined by lumbar (L(1)-L(4)) bone mineral density (BMD), long-bone and/or symptomatic vertebral fractures. Lumbar BMD was reported as height-adjusted Z-scores at initiation of deflazacort (T(0)) and 1-2 year intervals thereafter. Subcapital body fat percentage and ambulatory status were recorded. At T(0), 39 boys, aged 6.6 ± 1.6 years had height-adjusted BMD Z-score -0.5 ± 0.8, and 23.5 ± 5.0% body fat. Height-adjusted Z-scores remained stable with years of deflazacort until loss of ambulation and accrual of body fat. Nine long-bone fractures occurred in eight ambulating boys, two before T(0). Seven vertebral fractures occurred in six non-ambulatory boys after ≥ 5 years of deflazacort with height-adjusted Z-score -1.8 ± 0.7, and 47.8 ± 12% body fat. Bone health in DMD is influenced by disease progression, corticosteroids, BMD Z-scores and fat mass accumulation. Adjustments for short stature must be considered during BMD interpretation. Percent body fat and ambulatory status are useful bone health indicators. Routine use of height adjusted Z-scores is advocated for use in routine clinical practice.

Isobolographic analysis of the interactions between midazolam and propofol at GABA(A) receptors in embryonic mouse neurons.

BACKGROUND: Clinical studies suggest that midazolam and propofol interact synergistically to induce hypnosis, but these drugs do not interact synergistically to prevent movement in response to noxious stimuli. The mechanisms underlying these interactions are not certain but may occur at the level of the gamma-aminobutyric acid A (GABA(A)) receptor. METHODS: The authors evaluated the interactions between propofol and midazolam in modulating GABA(A) receptor activity in embryonic hippocampal neurons. The effects of midazolam and propofol on peak current evoked by submaximal concentrations of GABA were studied using the patch clamp method. Isobolographic analysis was undertaken by constructing concentration-response curves for midazolam and propofol alone and then evaluating the potency of combinations of midazolam and propofol. In other experiments, the concentration of GABA was increased and flurazepam was substituted for midazolam. RESULTS: Isobolographic analysis confirmed that midazolam and propofol interact synergistically to enhance currents evoked by low concentrations of GABA (1 microM). However, when the concentration of GABA was increased to 3 microM, the interaction was additive. The interaction between flurazepam and propofol was also additive for enhancement of currents evoked by 3 microM GABA. CONCLUSIONS: The interaction between midazolam and propofol was critically dependent on the concentration of GABA: Synergism was evident at low concentrations of GABA, but an additive interaction was apparent when the concentration of GABA was increased. Changes in GABA(A) receptor function may underlie the synergistic interaction between propofol and midazolam for clinical effects such as hypnosis. The clinical implication of the results is that the benefits of synergism observed at one concentration ratio of these drugs may not be apparent at another.

Autocrine secretion of TGF-beta 1 and TGF-beta 2 by pre-adipocytes and adipocytes: a potent negative regulator of adipocyte differentiation and proliferation of mammary carcinoma cells.

We have developed an in vitro system to examine the influence of adipocytes, a major mammary stromal cell type, on the growth of a murine mammary carcinoma, SP1. Previously, we have shown that 3T3-L1 adipocytes release a mitogenic factor, hepatocyte growth factor, which strongly stimulates proliferation of SP1 cells. We now show that 3T3-L1 pre-adipocytes secrete active inhibitory molecules which inhibit DNA synthesis in SP1 cells. In addition, latent inhibitory activity is present in conditioned media (CM) from both pre-adipocytes and adipocytes, and is activated following acid treatment. CM also inhibited DNA synthesis in Mv1Lu wild type epithelial cells, but not DR27 mutant epithelial cells which lack TGF-beta type II receptor. Inhibitory activity of CMs was partially abrogated by neutralizing anti-TGF-beta1 and anti-TGF-beta2 antibodies, and was removed following ultrafiltration through membranes of 10,000 Mr but not 30,000 Mr pore size. These results show that the inhibitory effect on DNA synthesis is mediated by TGF-beta1-like and TGF-beta2-like molecules. In addition, acid-treated CM as well as purified TGF-beta inhibited differentiation of pre-adipocytes. Untreated pre-adipocyte CM, but not mature adipocyte CM, spontaneously inhibited adipocyte differentiation. Together, these findings indicate that pre-adipocytes spontaneously activate their own secreted TGF-beta, whereas mature adipocytes do not, and suggest that activation of TGF-beta has a potent negative regulatory effect on adipocyte differentiation and tumor growth. Thus, TGF-beta may be an important modulator of tumor growth and adipocyte differentiation via both paracrine and autocrine mechanisms. These findings emphasize the importance of adipocyte-tumor interactions in the regulation of tumor microenvironment.

General anaesthetics and their effects on GABA(A) receptor desensitization.

1. Intravenous anaesthetics, including propofol and thiopental have at least three distinct effects on GABA(A) receptor function. 2. Low concentrations of these drugs enhance the amplitude of currents evoked by sub-saturating concentrations of GABA whereas higher concentrations directly activate the receptor in the absence of GABA. 3. Propofol and some barbiturates also decrease the rate and extent of desensitization as indicated by a prolongation in the decay of currents evoked by saturating concentrations of GABA. 4. In contrast, sedative benzodiazepines that lack general anaesthetic properties do not directly activate the GABA(A) receptor. 5. In addition, benzodiazepines such as midazolam, have no effect on desensitization when examined in the presence of saturating concentrations of GABA. 6. Here, we discuss the effects of intravenous general anaesthetic on desensitization of the GABA(A) receptor.

Identification of a hepatocyte growth factor autocrine loop in a murine mammary carcinoma.

Constitutive activation of growth factor receptors through autocrine/paracrine mechanisms occurs frequently in human cancers and is thought to play an important role in carcinogenesis. We have demonstrated previously that hepatocyte growth factor (HGF) is a potent mitogenic factor for murine mammary carcinoma (SP1) cells in vitro. We report here an autocrine HGF loop in SP1 cells. HGF receptor/Met is expressed in SP1 cells and is constitutively tyrosine phosphorylated. The phosphorylation of HGF receptor/Met is inhibited when cells are exposed to suramin or anti-HGF IgG. This finding suggests that constitutive tyrosine phosphorylation of HGF receptor/Met is sustained by an extracellular factor, most likely HGF. Using Northern blot and Western blot analysis, we detected expression of a 6-kb HGF mRNA in SP1 cells and a M(r) 85,000 HGF protein in SP1-conditioned medium, respectively. In vitro translation of mRNA from SP1 cells and metabolic labeling confirmed expression and synthesis of HGF by SP1 cells. SP1 cells also invade through Matrigel-coated transwell membranes in an in vitro invasion assay, and invasion of these cells was inhibited by neutralizing anti-HGF IgG. In addition, SP1-conditioned medium induced scatter activity of Madin-Darby canine kidney epithelial cells, and this activity was inhibited by neutralizing anti-HGF IgG. We have also shown that several signaling molecules including phosphatidylinositol 3-kinase, Src, focal adhesion kinase, and phospholipase C-gamma in SP1 cells are constitutively tyrosine phosphorylated, suggesting that coexpression of HGF and HGF receptor/Met may in part contribute to sustained tyrosine phosphorylation of these cytoplasmic proteins in SP1 cells. Our observations in the SP1 model suggest that HGF contributes to growth and invasive phenotypes of mammary carcinomas via both paracrine and autocrine mechanisms.

Immunologic abnormalities in hemodialysis patients: improvement after pyridoxine therapy.

8 male patients undergoing maintenance hemodialysis were studied to determine the effect of administering supplements of pyridoxine hydrochloride, 50 mg/day for 3-5 weeks, on tests of immune function. In the 3 patients who initially had abnormal nitroblue tetrazolium reduction tests, the values returned to normal with therapy (p less than 0.05). The generation of chemotactic factors from plasma was defective in all evaluated patients and improved after pyridoxine therapy in 4 of 5 patients (p less than 0.01). The lymphocyte subpopulations changed with a rise in the populations of null cells after supplementation with pyridoxine. In addition, lymphocyte transformation in response to mitogens improved in the 3 patients who initially showed low values in these assays. The improvements occurred with pyridoxine therapy even though some patients who responded had no evidence for vitamin B6 deficiency before therapy, as indicated by a normal erythrocyte glumatic-pyruvic transaminase index. We conclude that several parameters of immune function are improved with pyridoxine supplementation. Studies are necessary to establish the minimum daily intake of pyridoxine which will maintain improved values of these tests of immune function in hemodialysis patients.

Scleromyxedema myopathy. Histochemical and electron microscopic observations.

A biopsy-proven case of scleromyxedema (papular mucinosis) with IgG lambda light chain paraproteinemia, eosinophilia and severe proximal myopathy is presented. Muscle biopsy revealed an atypical necrotizing vacuolar myopathy. Histochemical studies of cryostat sections revealed fiber necrosis, severe type II fiber atrophy, and fiber vacuolization with NADH tetrazolium reductase hyperactivity. Electron microscopy showed myocytolysis, reduplication of the basement membrane, and unit membrane-lined vacuoles negative for acid mucopolysaccharide.

Papular mucinosis with myopathy, arthritis, and eosinophilia. A histopathologic study.

A patient with biopsy-proven papular mucinosis, plus the characteristic IgG lambda light chain paraproteinemia, also developed a severe proximal myopathy, seronegative inflammatory polyarthritis, and marked eosinophilia. Muscle enzymes were elevated, EMG was compatible with polymositis, and muscle biopsy revealed an atypical necrotizing vacuolar myopathy. Synovial biopsy revealed an inflammatory synovitis with Class II synovial fluid. No mucin deposition was detectable in muscle or synovium. During 7 years of observation, corticosteroids and various immunosuppressive agents were successively administered with little benefit. Recently, weekly intravenous methotrexate and low-dose oral corticosteroids have resulted in clinical and laboratory improvement. It is suggested that the pathology in papular mucinosis may include serious rheumatic manifestations in addition to the cutaneous involvement.

Acute gastric mucosal injury during continuous or interrupted aspirin ingestion in humans.

The effect of continuous versus interrupted high-dose aspirin (ASA) for 14 days was evaluated in a randomized double-blind study in 8 rheumatoid arthritis patients. Acute gastric mucosal injury was measured by serial gastroscopy and gastric biopsy. Significant gross mucosal damage was seen in all patients following 3 days of ASA (P less than 0.01) and persisted without significant change in severity to the end of the study. Histologic gastritis in areas free of hemorrhages and erosions was not increased significantly by ASA. In spite of gross mucosal injury, symptoms occurred infrequently. Serum pepsinogen I, but not serum gastrin, increased significantly following 3 days of ASA, and the elevation persisted to the end of the study. The extent of mucosal injury at 14 days was not significantly different in those receiving ASA continuously from those on an interrupted schedule. Thus, gastric mucosal adaptation to ASA in man was not demonstrated.

Clinical and radiological survey of the incidence of osteoarthrosis among obese patients.

Twenty-five grossly obese males were investigated for evidence of osteoarthrosis. A roentgenological survey of multiple joints obtained from 22 of these patients showed few significant degenerative changes. 6 patients (20%) had previously incurred traumatic rents in their menisci necessitating meniscectomy. Our results refute previous claims that obesity is a factor in the genesis of osteoarthrosis but do indicate that obese individuals are more predisposed to traumatic injury of the knee.

Relapsing polychondritis: prospective study of 23 patients and a review of the literature.

Relapsing polychondritis (RP) is not a totally rare rheumatic disease. We have seen 23 patients from 1960-1975, and there are now a total of 159 reported cases, which form the basis of this study. RP occurs equally in both sexes, and has a maximum frequency in the fourth decade. 2) Empirically defined diagnostic criteria are proposed, to include the most common clinical features: a) Bilateral auricular chondritis b) Nonerosive sero-negative inflammatory polyarthritis c) nasal chondritis d) Ocular inflammation e) Respiratory tract chondritis f) Audiovestibular damage The diagnosis is based primarly upon the unique clinical features, and is quite certain if three or more criteria are present together with histologic confirmation. 3) Fifty percent of patients present with either auricular chondritis or the arthropathy of RP; but with prolonged follow-up, a majority of patients develop four or more of the above mentioned criteria. 4) Approximately 30 percent of patients have a preceding or coexistent rheumatic or autoimmune disease, which can lead to initial diagnostic confusion. 5) Laboratory and radiographic investigations help mainly to rule out other diagnostic possibilities, with no characteristic abnormalities being present in a majority of patients. 6) On follow-up, three-fourths of our patients required chronic corticosteroid therapy with an average dose of 25 mg per day of prednisone. Corticosteroids decrease the frequency, duration, and severity of flares, but do not stop disease progression in severe cases. 7) The mortality rate has been 30 percent in our series and 22 percent in the other 136 reported cases. Of the 29 cases where the cause of death was known, 17 were from respiratory tract involvement and 9 from cardiac valvular or vasculitic involvement, emphasizing the need to search for critical involvement of either of these organ systems in each patient. 8) Detailed reports of selected cases are presented to illustrate the clinical diagnosis and differential diagnosis, and to demonstrate the need for careful prolonged follow-up. 9) Although the etiology remains unknown, there is a frequent association with, and clinical similarity to, other rheumatic diseases. 10) Careful clinicopathological study of our 23 patients leads us to postulate an underying systemic vascultis as an important pathologic mechanism in RP.

The arthropathy of relapsing polychrondritis.

Twenty-three adults (11 males and 12 females) with well-defined relapsing polychondritis (RP) are studied in order to characterize the arthropathy of RP. Arthritis was found in 19 patients-as the presenting feature in 8 and as a significant symptom in 11 others. The usual pattern of involvement was migratory, asymmetric, non-nodular, nonerosive, and seronegative, and affected large and small joints as well as parasternal articulations. In addition RP was seen in 3 patients with preexisting chronic polyarthritis or associated rheuamtic disease.