Cardiac pacing in Canada in 1998: working towards optimal pacing therapy. Canadian Working Group on Cardiac Pacing

The Canadian Working Group on Cardiac Pacing (CWGCP) was formed in 1996 with the primary goal of promoting optimal pacing therapy in Canada. In 1997, the CWGCP conducted a survey of pacing practices across Canada. Ninety-two of 125 implanting programs (74%) responded. Implant rates vary by province--from 39 per 100,00 population in Ontario to 63 per 100,000 population in Nova Scotia and Prince Edward Island. Variations in regional implant rates persist even after correcting for the age of the population. Physiological pacing was used for 35% of all implants in Canada in 1996/97. There were marked differences across Canada in the mode of pacing selected. In western Canada, 39.5% of pacing systems implanted were physiological compared with 18.2% in Atlantic Canada and 29% in Quebec. There were also differences in follow-up practices. Approximately 40% of centres follow patients with single chamber pacemakers annually, whereas most other centres still follow these patients every six months. Economic constraints, the size of pacing programs and the involvement of committed pacing physicians are factors that may influence the regional differences in cardiac pacing across Canada.     

Neuronal nitric oxide synthase in the canine prostate: aging, sex steroid, and pathology correlations

OBJECTIVE: To clarify some anatomical controversies of the fascial structures and lymph node development of the inguinal region through an embryological study in relation to the surgical techniques of groin lymphadenectomy. METHODS: Sections of the femoral triangle belonging to four fetuses whose crown-rump (CR) length ranged from 70 to 310 mm, corresponding to a developmental age of 11 and 35 weeks, were studied. RESULTS: The femoral fascia is formed of one layer and is not divided into superficial and deep layers. The cribriform fascia has a morphogenetic origin different from that of the femoral fascia and it is defined by the thickening of the connective tissue filling the fossa ovalis and therefore would be more correctly named lamina cribrosa. The deep inguinal lymph nodes originate directly from the superficial lymphatic tissue located in the fossa ovalis. This last observation supports the fact that no lymph nodes are present beneath the femoral fascia distal to the lower margin of the fossa ovalis. CONCLUSIONS: The results of this study, from a surgical point of view, support the technique of total or radical inguinal-femoral lymphadenectomy with preservation of the femoral fascia and, from an anatomical point of view, resolve some of the contradictory statements reported in the anatomical literature regarding morphogenesis and terminology of the structures of the Scarpa's triangle. In addition, the present study provides useful anatomic and terminological landmarks to those surgical oncologists (gynecologist, urologist, dermatologist, etc.) dealing with malignant diseases requiring groin dissection practices. In addition, it could represent a useful background for a future more precise surgical terminology which represents a vital issue for institutional studies with multiple surgeons as well as for large multi-institutional studies.     

Home health care

Home health care is the fastest-growing expense in the Medicare program because of the aging population, the increasing prevalence of chronic disease and increasing hospital costs. Patients and families are choosing the option of home care more frequently. Medicare's regulations are often considered the standard of care for all home health agency interactions, even when a patient does not have Medicare insurance. These regulations require patients who receive home health care services to be under the care of a physician and to be homebound. The patient must have a documented need for skilled nursing care or physical, occupational or speech therapy. The care must be part time (28 hours or less per week, eight hours or less per day) and occur at least every 60 days except in special cases. A detailed referral and specific care plan maximize the care to the patient and the reimbursement received by the physician.     

Intraarterial vs intravenous administration of antivenin for the treatment of Crotalidae atrox envenomation: a pilot study

OBJECTIVE: Standard therapy for significant snake envenomation includes antivenin. i.v. administration is currently the only recommended route. Intraarterial (i.a.) administration has potential advantages over i.v. that could improve outcome. To study this, the authors compared i.v. and i.a. antivenin administrations for the treatment of experimental snake envenomations. METHODS: 14 adult female swine were anesthetized and prepared with femoral artery and ear vein catheters, and baseline hoof, forearm, and thigh circumference and volume displacement measurements were taken. Crotalidae atrox venom was injected into the subcutaneous tissue of the hoof. The doses of venom were 4.75, 9.50, 19.00, 37.90, 47.30, 56.90, and 66.40 mg. Immediately following injection of venom, polyvalent antivenin (Crotalidae) (0.285 mg/10 mL saline) was infused over 30 minutes into the femoral artery (i.a. group) or ear vein (i.v. group). As a control, 10 mL of saline was infused into the ear vein (i.a. group) or femoral artery (i.v. group). Measurements were recorded up to 48 hours. Linear mixed-effect regression models were used for each measurement and to compare the i.a. and i.v. groups. RESULTS: Venom dose and time after administrations were associated with increased circumferences and increased volumes (p < 0.05). i.v. administration was associated with larger hoof (1.26 cm) and forearm (0.42 cm) sizes and volume displacement (21.71 mL) when compared with i.a. administration ( p < 0.05). CONCLUSION: i.a. antivenin results in a modest but significant decrease in tissue edema when compared with i.v..     

Inhibition of lipolysis reduces beta1-adrenoceptor-mediated thermogenesis in man

The purpose of the study was to investigate whether the increase in energy expenditure and lipid oxidation during beta1-adrenergic stimulation is caused by the concomitant increase in lipolysis. Twelve healthy male subjects participated in three trials: no-LIP/-, inhibition of lipolysis by pretreatment with acipimox followed by saline infusion; -/BETA, no pretreatment, with dobutamine infusion to stimulate beta1-adrenoceptors; and no-LIP/BETA, pretreatment with acipimox followed by dobutamine infusion. Inhibition of lipolysis did not affect baseline energy expenditure, but decreased lipid oxidation and increased carbohydrate oxidation. Energy expenditure and lipid oxidation increased significantly during beta1-adrenergic stimulation, but this increase was significantly smaller when lipolysis was inhibited ([baseline v infusion period] energy expenditure: -/BETA, 5.15 +/- 0.16 v 6.11 +/- 0.26 kJ/min, P < .001; no-LIP/BETA, 5.28 +/- 0.17 v 5.71 +/- 0.19 kJ/min, P < .01; lipid oxidation: -/BETA, 0.059 +/- 0.004 v 0.073 +/- 0.006 g/min, P < .01; no-LIP/BETA, 0.034 +/- 0.005 v 0.039 +/- 0.006 g/min, P < .05). Baseline plasma glycerol and nonesterified fatty acid (NEFA) concentrations decreased after inhibition of lipolysis. Glycerol and NEFA increased significantly during beta1-adrenergic stimulation alone (glycerol, 65.0 +/- 5.3 v 117.0 +/- 10.9 micromol/L; NEFA, 362 +/- 24 v 954 /- 89 micromol/L; both P < .001). Concomitant administration of acipimox prevented a substantial part of the increase in lipolysis during beta1-adrenergic stimulation, but the increase in plasma glycerol and NEFA remained significant (glycerol, 40.4 +/- 2.2 v 44.8 +/- 2.2 micromol/L; NEFA, 118 +/- 18 v 160 +/- 19 micromol/L; both P < .05). In conclusion, a reduced availability of plasma NEFA was associated with a reduced increase in energy expenditure and lipid oxidation during beta1-adrenergic stimulation in man.     

Microsatellite instability of genome in cells of sporadic and hereditary carcinoma of the gastrointestinal tract

Prostaglandins have been reported to mediate the effects of ovariectomy on bone loss. We studied the effect of naproxen, an inhibitor of production of prostaglandins, on ovariectomy-induced bone loss. One hundred forty female Wistar rats 4.5 months of age were divided into groups of baseline, sham operation (sham), sham treated with naproxen at 10 mg/kg per day (in food), and ovariectomy treated with naproxen or estrogen as intramuscular injection of estradiol at 0.2 mg/kg body weight per week. They were killed 3, 6, and 9 months postsurgery. Bone mineral density (BMD) of the lumbar spine (L1-4), femoral neck, midshaft, and distal metaphysis was determined using dual-energy X-ray absorptiometry (DXA) in vitro. The compressive test of the L1 vertebral body and torsional test of the left femur were performed. The right femoral neck and femoral midshaft were processed undecalcified for determining cross-sectional moments of inertia. Naproxen treatment partially prevented ovariectomy-induced loss or less gain in BMD, in a significant manner, in the femoral neck cortical area, and also in L1 compressive strength and stiffness. Estrogen fully prevented these ovariectomy-induced effects. Naproxen showed no effect on ovariectomy-induced improvement in femoral torsional strength and stiffness and cross-sectional moments of inertia. No statistically significant difference was found between naproxen-treated sham rats and untreated sham rats. The data suggest that naproxen partially prevents ovariectomy-induced osteopenia.     

Synaptic and glial localization of the integrin alphavbeta8 in mouse and rat brain

Integrins are a large family of cell adhesion receptors mediating cell-extracellular matrix (ECM) interactions and are widely distributed in tissues. The beta8 integrin subunit mRNA has been shown to be expressed at higher levels in the central nervous system (CNS) than in other organs [M. Moyle, M.A. Napier, J.W. McLean, Cloning and expression of a divergent integrin subunit beta8, J. Biol. Chem. 266 (29) (1991) 19650-19658] but its cellular and subcellular localization in the CNS are unknown. In this report, we demonstrate that beta8 pairs exclusively with the alphav subunit in the CNS to form the alphavbeta8 heterodimer. Immunohistochemical analysis of the distribution of beta8 in adult mouse and rat brains revealed that the protein is expressed in several regions of the hippocampal formation and in the molecular layer and glomeruli of the granular cell layer of the cerebellum. Punctate and diffuse immunolabeling was observed occasionally surrounding neuronal pericarya and extensively throughout dendritic fields suggesting both pre- and post-synaptic localization and/or expression in non-neuronal cells. By immunoelectron microscopy, beta8 immunoreactivity was detected in dendritic spines where it was often localized at post-synaptic densities, occasionally in axon terminals and in glial processes. Association of beta8 with synaptic membranes was further supported by its enrichment in synaptosomal preparations as detected by immunoblotting. These results demonstrate that alphavbeta8 is present in mature synapses and therefore may play a role in synaptic function.     

Exposure to toxic air contaminants in environmental tobacco smoke: an assessment for California based on personal monitoring data

The contribution of environmental tobacco smoke (ETS) to the exposure of adult nonsmoking Californians was determined for selected toxic air contaminants (TACs). The assessment was based on published measurements of ETS emission factors and personal exposures to volatile organic compounds. The human exposure studies were conducted in three California areas--Los Angeles, Pittsburgh/Antioch, and Woodland--between 1984 and 1990. We derived unexposed and passive population exposure distributions by randomly sampling the monitoring results for individuals classified according to exposure status (active smoker, passively exposed or unexposed to ETS during monitoring). The differences between the unexposed and passive distributions were used to estimate the ETS-only contribution for exposure to benzene, styrene, o-xylene, and m,p-xylene. Emission factors were then employed to infer the ETS-caused exposure to thirteen other compounds. The estimated arithmetic mean increments of 24-hour exposure attributable to ETS for the nonsmoking Californian population (age > or = 7) exposed to ETS are as follows (results in units of microgram m-3 exposure concentration; results using two different emission factors presented as a range): acetaldehyde 11-15; acetonitrile 7.0; acrylonitrile 0.49; benzene 1.02; 1,3-butadiene 0.75-2.3; 2-butanone 1.4; o-cresol 0.17; m,p-cresol 0.41; ethyl acrylate < 0.015; ethylbenzene 0.49-0.64; formaldehyde 6.5-8.2; n-nitrosodimethylamine 0.0028; phenol 1.4; styrene 0.36; toluene 3.1-3.2; o-xylene 0.77; m,p-xylene 0.99. The 90% confidence limits on these estimates due to the limited sample size in the studies are roughly x/ divided by 6. For four widely studied compounds, ETS is estimated to contribute the following percentages to the total inhalation exposure of all nonsmoking Californians: o-xylene 5%; m,p-xylene 3%; benzene 5%; and styrene 8%.     

Dental laminates: which technique?

A direct laboratory technique for fabricating dental laminate restorations is described; the method provides good soft tissue compatibility and esthetic appearance with reduced chair time and enhanced patient comfort.