Ventricular repolarization time, location of pacing stimulus and current pulse amplitude conspire to determine arrhythmogenicity in mice.

AIM: In this study, we investigate the impact of altered action potential durations (APD) on ventricular repolarization time and proarrhythmia in mice with and without genetic deletion of the K+ -channel-interacting protein 2 (KChIP2-/- and WT respectively). Moreover, we examine the interrelationship between the dispersion of repolarization time and current pulse amplitude in provoking ventricular arrhythmia. METHODS: Intracardiac pacing in anesthetized mice determined refractory periods and proarrhythmia susceptibility. Regional activation time (AT), APD and repolarization time (=AT + APD) were measured in isolated hearts using floating microelectrodes. RESULTS: Proarrhythmia in WT and KChIP2-/- was not sensitive to changes in refractory periods. Action potentials were longer in KChIP2-/- hearts compared to WT hearts. Isolated WT hearts had large apico-basal dispersion of repolarization time, whereas hearts from KChIP2-/- mice had large left-to-right ventricular dispersion of repolarization time. Pacing from the right ventricle in KChIP2-/- mice in vivo revealed significant lower current pulse amplitudes needed to induce arrhythmias in these mice. CONCLUSION: Large heterogeneity of repolarization time is proarrhythmic when pacing is delivered from the location of earlier repolarization time. Ventricular repolarization time, location of the pacing stimulus and the amplitude of the stimulating current pulse are critical parameters underlying arrhythmia vulnerability.

Anoctamin 6 differs from VRAC and VSOAC but is involved in apoptosis and supports volume regulation in the presence of Ca2+.

Anoctamin 6 (ANO6), also known as TMEM16F, has been shown to be a calcium-activated anion channel with delayed calcium activation. The cellular function of ANO6 is under debate, and different groups have come to different conclusions about ANO6's physiological role. Although it is now quite well established that ANO6 is distinct from the volume-regulated anion channel, it is still unclear whether ANO6 or other anoctamins can be activated by cell swelling. In this study, we suggest that ANO1, ANO6, and ANO10 do not contribute to the volume-activated current in ANO-overexpressing HEK293 cells. Furthermore, knock-down of ANO6 in Ehrlich ascites tumor cells (EATC) and Ehrlich-Lettre ascites (ELA) did not decrease but instead significantly increased swelling-activated membrane currents. Knock-down of ANO6 in EATC did not reduce regulatory volume decrease (RVD) in the absence of extracellular calcium, whereas it significantly reduced RVD in the presence of calcium. Interestingly, we found that knock-down of ANO6 in ELA cells resulted in a decrease in cisplatin-induced caspase-3 activity, confirming earlier findings that ANO6 is involved in apoptosis. Finally, knock-down of ANO1 and ANO6 did not affect the volume-sensitive release of taurine in ELA cells. Thus, our data provide evidence that ANO6 cannot be activated directly by cell swelling unless Ca(2+) is present. We also conclude that ANO6 carries a current during RVD, provided extracellular calcium is present. Thus, swelling activation of ANO6 requires the presence of free calcium.

Contamination skin doses and attenuation of radiation by clothing.

The potential operating environment following an attack using CBRN (chemical, biological, radiological, nuclear) materials has led to design work aiming to reduce the physiological burden of protective clothing, while maintaining satisfactory levels of chemical protection. In this paper, we review the radiological protection provided by these lighter, thinner clothing options. Monte Carlo modelling has been used to determine the contribution to skin dose from both beta and gamma radiation from four sources, each with different emission characteristics. The protection factors for eight materials have been characterised in terms of the surface density of each material (ranging from 50 to 482 g m⁻²). As protective clothing is made lighter and more breathable, the radiological protection is significantly reduced. This work has provided quantitative analysis of the magnitude of this reduction. A simple algorithm has been derived which can be used to estimate the protection factor for any clothing, on the basis of the surface density of the material (within the range of materials studied). These results show the need for skin radiation exposure to be considered by protective suit designers and CBRN response planners.

A novel magnetic approach to enhance the efficacy of cell-based gene therapies.

Attempts have been made to use various forms of cellular vectors to deliver therapeutic genes to diseased tissues like malignant tumours. However, this approach has proved problematic due to the poor uptake of these vectors by the target tissue. We have devised a novel way of using magnetic nanoparticles (MNPs) to enhance the uptake of such 'therapeutically armed' cells by tumours. Monocytes naturally migrate from the bloodstream into tumours, so attempts have been made to use them to deliver therapeutic genes to these sites. However, transfected monocytes injected systemically fail to infiltrate tumours in large numbers. Using a new in vitro assay for assessing monocyte extravasation, we show that the ability of transfected human monocytes to migrate across a human endothelial cell layer into a 3D tumour spheroid is markedly increased when cells are pre-loaded with MNPs and a magnetic force is applied close to the spheroid. Furthermore, systemic administration of such 'magnetic' monocytes to mice bearing solid tumours led to a marked increase in their extravasation into the tumour in the presence of an external magnet. This new magnetic targeting approach could be used to increase the targeting, and thus the efficacy, of many cell-based gene therapies in vivo.

Cervical discography: clinical implications from 12 years of experience.

STUDY DESIGN: Positive pain responses provoked in an inclusive series of cervical discograms performed over a 12-year period were categorized by level and reviewed. OBJECTIVES: To report the prevalence of cervical pathology over an entire series of patients, to determine whether a reproducible pattern of concordant pain could be associated with each symptomatic level identified, and to calculate the rate of complications. SUMMARY OF BACKGROUND DATA: Cloward wrote the first articles explaining the technique of cervical discography and reported on the pain responses induced. Currently, the technique is viewed as an invaluable diagnostic tool, but it also is criticized for failing to contribute unique information beyond that available from imaging studies despite the inherent risks. METHODS: A series of 173 cervical discograms performed over 12 years was examined. Pain responses provoked and recorded during discography were grouped by disc level and examined for recurring patterns. The prevalence of disc pathology was calculated. RESULTS: In all, 807 discs were injected, and 404 concordant pain responses (50%) were elicited. Three or more abnormal disc levels were identified in more than half of the patients. Complications developed in four patients (2.3%). No further complications were reported. Surgical treatment was indicated as viable in only 35 studies. CONCLUSIONS: Discography is a safe and valuable diagnostic procedure showing characteristic pain patterns that may have clinical significance. In more than half of the studies, three or more levels were identified as pain generators, suggesting that treatment decisions based on information from fewer discs injected during discography may be tenuous.

Results of surgical treatment of painful adult scoliosis.

STUDY DESIGN: In a consecutive clinical series, using before and after treatment measures, outcome was evaluated in adults with pain and scoliosis who underwent spinal fusion. OBJECTIVE: This outcome study tested the hypothesis that adult scoliosis patients with chief complaints of pain can have good results, reflected in decreased pain and increased activity postoperatively, when surgical intervention is based not only on analysis of structural deformity, but also on comprehensive evaluation of pain-producing pathology. METHODS: Twenty-eight adults with idiopathic scoliosis and 25 adults with degenerative scoliosis treated with spinal fusion were followed prospectively for 2 to 7 years. All patients had chief complaints of pain and underwent comprehensive evaluations of pain-producing pathology, as well as evaluations of structural deformity. Before initial evaluations, patients completed questionnaires including pain rating, activity level specifically related to standing, sitting, and walking tolerances, ability to work, and period of disability. At a minimum of 24 months postop, patients completed confidential questionnaires seeking report of pain, activity, and work status. These data were compared to responses obtained before surgery. Pseudoarthroses were assessed by superimposed flexion/extension films. RESULTS: The pseudoarthrosis rate was 17.5%, all occurring in patients fused to the sacrum in single posterior procedures. Pain relief was associated with solid fusion (P = .02). Reported pain reduction was 80% among patients with idiopathic scoliosis and 70% among patients with degenerative scoliosis. Improved sitting and walking tolerances were seen in patients with idiopathic scoliosis, and improved standing and walking were seen in patients with degenerative scoliosis.

Diagnostic findings in painful adult scoliosis.

The purpose of this study was to document the diagnostic findings in a group of adult patients presenting with both scoliosis and pain. Fifty-five adults were evaluated by medical history, physical examination, radiography, myelography followed by computed tomography, discography followed by computed tomography, and single- and dual-photon densitometry. Curves were 49% adult degenerative onset, 44% idiopathic. The older degenerative patients had myelographic defects most commonly within the primary curve and multiple abnormal, not necessarily painful, discs throughout the lumbar spine on discography. The idiopathic group had myelographic defects most commonly in a compensatory lumbar or lumbosacral curve. On discography, all idiopathic patients had at least one abnormal, painful disc, and 88% had their pain reproduced. Pain-producing pathology was frequently identified in areas that would not have been included in the fusion area according to accepted rules for treatment of idiopathic scoliosis.

Results of lumbosacral fusion for degenerative disc disease with and without instrumentation. Two- to five-year follow-up.

Functional and surgical outcomes are reported in two consecutive groups of patients who underwent one- and two-level lumbosacral fusion. The first group underwent standard posterolateral lumbosacral fusion, and the second group underwent lumbosacral fusion with compression U-rod instrumentation. Fusions were carried out over all painful, abnormal levels documented by discography. the pseudarthrosis rate without instrumentation was 35%, in contrast to 6% with instrumentation. In both groups of patients with chronic low-back pain secondary to degenerative disc disease, solid lumbosacral fusion was associated with decreased pain and higher return to work rates. Poorest results were associated with prolonged periods of preoperative disability and long-term disability claims.

Monocytic origin of fibroblasts: spontaneous transformation of blood monocytes into neo-fibroblastic structures in osteomyelosclerosis and Engelmann's disease.

We describe here two pathological situations, osteomyelosclerosis and Engelmann's disease, in which HLA-DR blood monocytes modulate to the fibroblastic class, in long-term culture. Monocytes/macrophages were identified by immunofluorescence, using monoclonal antibodies against surface markers (Leu M3, CD 68, and HLA-DR) and the neo-fibroblasts by electron microscopy and immunofluorescence using monoclonal antibodies against a cytoplasmic enzyme specifically involved in the synthesis of collagen (5B5). Macrophages makers were found on the neo-fibroblasts, whereas HLA-DR macrophages expressed the cytoplasmic marker 5B5. Since osteoblasts are classically derived from fibroblasts, the significance of the in vitro differentiation of monocytes/macrophages into fibroblasts to the in vivo mechanism leading to excessive osteoblastic proliferation in both osteomyelosclerosis and Engelmann's disease, is discussed. The possible involvement of this pathway leading from monocytes to fibroblasts and osteoblasts in the normal process of bone modeling and remodeling in questioned.

Effectiveness of low-dose lovastatin in lowering serum cholesterol. Experience with 56 patients.

This study reviews the progress of 56 consecutive patients with type IIa and IIb hyperlipoproteinemia following treatment with lovastatin. Lovastatin, a potent inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, has been shown to have a cholesterol-lowering effect in doses ranging from 10 to 80 mg/d. Thus far, however, no large study has been performed to show the effectiveness of low-dose lovastatin (20 mg/d) for more than a 6-week duration. Fifty-six patients with known coronary artery disease were prospectively studied, with fasting lipid values being measured at baseline and after 6, 12, 18, and 24 weeks of 20-mg/d lovastatin therapy given as a single evening dose. The total cholesterol level fell 26% from a mean baseline of 8.12 mmol/L (314 mg/dL) and triglyceride levels fell by 12% from a mean baseline of 2.46 mmol/L. The high-density lipoprotein levels increased 7.6%. One patient with known preexisting liver disease was withdrawn from the study owing to an asymptomatic significant rise in liver function test results; one subject complaining of proximal muscle weakness was also withdrawn. The maximal decrease in total cholesterol level occurred within 6 weeks of initiation of therapy. We conclude that low-dose (20-mg/d) lovastatin was effective in lowering serum cholesterol levels in patients with primary type IIa or IIb hyperlipoproteinemia with minimal short-term side effects. Further studies are needed to establish the long-term safety and effectiveness of this drug.

Colorimetric enumeration of Escherichia coli based on beta-glucuronidase activity.

A medium containing a chromogenic substrate was developed for the enumeration of Escherichia coli on the basis of beta-glucuronidase activity. In this medium there was an inverse linear relationship between the log initial E. coli concentration and the time taken for the color to reach a threshold optical density of 0.05. This relationship applied even when the E. coli population contained 5% beta-glucuronidase-negative cells. Incubation at 44 degrees C reduced the time taken for color development and allowed the procedure to be used in the presence of a competitive microflora that outnumbered the E. coli population by a factor of 10(4). Sodium lauryl sulfate as an additional selective agent gave no significant improvement. In the analysis of environmental water samples, the technique gave a good correlation with a standard cultural method. The procedure shows promise as a simple method for testing the compliance of environmental samples with microbiological criteria for E. coli.

Spinal bone density following spinal fusion.

Spinal bone densities were assessed in 25 patients following lumbar fusion and bracing, in an attempt to study bone remodeling by noninvasive methods. Dual-photon densitometry was used to study specific areas of autologous bone grafts and adjacent vertebrae above the fusion mass. Measurements were made preoperatively and at 6-week intervals postoperatively. The data for the first 12 months postoperatively are reported here. In all patients there was at first a consistent loss in density in the vertebrae above the fusion mass, averaging 15.7%. This was followed by a gradual density increase such that by 1 year postoperatively, in 60% of the subjects, the density of these vertebrae was higher than the preoperative level. In the grafted areas, bone changes were cyclical, demonstrating a remodeling pattern consistent with that described in animal literature for graft healing and also consistent with modern bone remodeling theory. There was a general tendency toward a gradual increase in the density of the fusion mass.

Degenerative adult onset scoliosis.

There are people who have no history of scoliosis who develop spinal deformity of a progressive nature as adults, associated with severe degenerative disc disease. The clinical syndrome associated with this deformity is not well documented. In an attempt to describe this clinical syndrome more precisely, 21 patients with the diagnosis of degenerative scoliosis were identified and reviewed. Review included history with pain drawings when available, physical examination, bone densities, and standing spinal roentgenograms. Patients with spinal compression fractures, spondylolyses, prior history of scoliosis or radiographic findings consistent with an idiopathic scoliosis were excluded. Our review shows that these patients can develop, along with progressive scoliosis, loss of lumbar lordosis with a resulting flat back deformity. These patients commonly present in the sixth decade with a predominantly stenotic symptom complex, but often lack the classic feature of relief in a sitting posture. The number of male and female patients was approximately equal. Roentgenogram findings show a high angle deformity over a short number of spinal segments and an absence of bony features associated with idiopathic scoliosis such as lateral vertebral wedging and alterations of the lamina. The incidence of this condition remains to be established.

The relative value of lumbar roentgenograms, metrizamide myelography, and discography in the assessment of patients with chronic low-back syndrome.

This prospective study evaluated the relative value of lumbar roentgenograms, metrizamide myelography, and discography in identifying structural sources for chronic low-back syndrome. One hundred and eight patients with chronic low-back syndrome were evaluated. Patients had not previously had pathology identified which could explain their pain. On discography, 83 patients (78%) had their pain reproduced at least one abnormal level, identifying a structural component to their pain. Only 22 patients (21%) had all levels of pathology identified by roentgenograms and an additional 17 (16%) had pathology appropriately identified by a combination of myelograms and roentgenograms. Using roentgenograms, myelography, and discography, organic pathology was identified which could explain the patient's symptoms in 100 of 108 patients (93%). Based on this study, we think discography is an important diagnostic tool for use in evaluating patients with chronic low-back syndrome. Discography is essential to adequately identify abnormal levels in patients being considered for fusions. Roentgenograms and myelograms are inadequate evaluation in this chronic pain group in that lack of organic pathology cannot be assumed in the presence of normal roentgenograms and myelograms.

Health variables and school achievement.

Students who failed the Cognitive Skills Assessment Battery (CSAB) at the beginning of first grade were compared to those who passed on health factors, health history, family characteristics, socioeconomic factors, health ratings by the classroom teacher and the school nurse, and achievement on the Basic Skills Assessment Program (BSAP) at the end of first grade. Significant differences were found on family characteristics, birth history, and health ratings. Only ear problems were significantly related to the academic variables. Health problems were found to be moderately related to academic variables. This relationship is influenced by family socioeconomic variables.

Bone density in women: a modified procedure for measurement of distal radial density.

This is a cross-sectional study of bone densitometry in greater than 700 normal healthy white women ranging in age from 18 to 98 years. A modified procedure for single-photon bone density analysis of the distal radius is described and compared with dual-photon densitometric measurements of the second through fourth lumbar vertebrae. The distal radial site measured was separated from the ulna by 5 mm. This "5 mm" site was characterized according to trabecular and cortical bone content, measurement reproducibility, positioning precision, and the effects of wrist pronation or supination. The radial site demonstrated a bone density loss of less than 0.1%/year for normal women 25-50 years of age, increasing to 0.7%/year after 50 years of age. In contrast to the variability and inconsistency obtained by us and others utilizing the standard "9/10" site, bone loss with age at the new "5 mm" site correlated closely with generalized bone mineral loss of the axial skeleton. We suggest that there is a unique role for single-beam densitometric measurements of the radius, permitting the rapid and relatively inexpensive evaluation of large populations of women without requiring a visit to a medical center. Such a process can select those requiring further evaluation or medical attention.

Bone density in osteopenic women: a modified distal radius density measurement procedure to develop an "at risk" value for use in screening women.

This study measured radial and lumbar spine bone density in postmenopausal white female patients with nontraumatic fractures and their age-matched controls. Bone density measurements were made with a single-beam densitometer. Distal radial bone density measurements were made at the site at which the radius and ulna are separated by 5 mm, which is approximately 5 mm from the distal radioulnar joint. Lumbar spine density was obtained using a dual-beam densitometer. Density at the commonly used "2/3" site near the midradius was also measured. Forty-six crush fracture osteoporotic patients, 35 hip fracture patients, and 20 osteopenic patients referred to the clinic for back pain or excessive bone loss but with no history of nontraumatic fracture were studied. Bone density values at all sites in the patient populations were statistically reduced from control values (p less than 0.01). At a mean age of 62 years, density of the midradius was 12% below the control value. However, both vertebral and distal radial densities ("5 mm" site) were 25% below control values. The spine/distal radius ratio remained constant. It was demonstrated that bone density at the modified distal radial site could be used to predict vertebral density in osteopenic patients. An "at risk" value useful in screening procedures was determined as that distal radius density value greater than or equal to 95% of all values from fracture patients--325 mg/cm2. It is concluded that distal radial density at the new "5 mm" site can be used in conjunction with midradius density as a preliminary test for both generalized and trabecular bone mass loss in women.