THE IMPACT OF GUN CONTROL (BILL C-51) ON SUICIDE IN CANADA

Suicide is a multiply determined behavior, calling for diverse prevention efforts. Gun control has been proposed as an important component of society's response, and an opportunity for studying the effects of legislative gun control laws on suicide rates was provided by Canada's Criminal Law Amendment Act of 1977 (Bill C-51). This article reviews previous studies of the impact of this act on the total population of Canada and subpopulations by age and gender and, in addition, presents the results of 2 new studies: a different method of analysis, an interrupted time-series analysis, and the results of a multiple regression analysis that controls for some social variables. It appears that Bill C-51 may have had an impact on suicide rates, even after controls for social variables.     

Genetic control of immunity to Heligmosomoides polygyrus: fixed H-2 E positive but not H-2 negative cells can present antigen to a parasite-specific T cell hybridoma

A number of T cell hybridomas were produced to adult worm homogenate (AWH) antigen of the nematode parasite Heligmosomoides polygyrus. All of the hybridomas were of the H-2^d haplotype and could potentially accept antigen in the context of either the A^d or E^d, H-2 molecules. Three types of antigen presentation were observed, with some of the T cell hybridomas accepting antigen in the context of the E and some in the context of the A molecule. A third type of hybridoma responded to antigen presented by paraformaldehyde fixed APC, but only when APCs were Epositive. These same hybridomas, were however, stimulated by A WH, when the antigen was presented by syngeneic but unfixed, E positive or E negative A PC. Therefore these data indicate that certain H. polygyrus-specfic T cell hybridomas can accept parasite antigen when presented in the context of either the H-2 A or E molecule, but the presentation of antigen by the two different MHC Class II molecules, can apparently utilize differing processing mechanisms.,     

Gastric and oesophageal emptying in insulin-dependent diabetes mellitus

Abstract Gastric emptying of a digestible solid and liquid meal and oesophageal emptying of a solid bolus were measured with scintigraphic techniques in 45 randomly selected insulin-dependent diabetics and in 22 control subjects. In the diabetics, the relationships between oesophageal emptying, gastric emptying, age, duration of diabetes mellitus, upper gastrointestinal symptoms, glycaemic control and the complications, autonomic neuropathy, peripheral neuropathy and retinopathy were examined. The lag period before solid food left the stomach was not significantly different in diabetics compared with control subjects, but the percentage retention of solid food at 100 min was greater ( P < 0.001) in the diabetic subjects. Both the early phase (percentage retention at 10 min) and the 50% emptying time for liquid gastric emptying were delayed ( P < 0.001) in the diabetic subjects. Of the diabetics, 58% had delayed gastric emptying of either the solid and/or the liquid meal; oesophageal emptying was delayed in 42%. Upper gastrointestinal symptoms correlated poorly with both gastric and oesophageal emptying. Oesophageal emptying, solid gastric emptying and the liquid 50% emptying time correlated with the severity of autonomic nerve dysfunction ( P < 0.05). The early phase of liquid emptying (retention at 10 min) was significantly slower ( P < 0.05) in patients with mean plasma glucose concentrations of > 15 mmol/l during the gastric emptying test and the lag period for solid emptying correlated with both the glycosylated haemoglobin and mean plasma glucose concentrations.     

Effect of interferon gamma on intrahepatic haemodynamics of the cirrhotic rat liver

Sublethal injury of the liver with carbon tetrachloride (CCI₄) induces the modulation of hepatic stellate cells to their myofibroblast (MFB) phenotype. Pretreatment or concomitant treatment with interferon gamma (IFNγ) has been shown to inhibit this phenomenon. The aim of this study was to investigate the influence of IFNγ treatment (50 000 IU s.c. each day for 5 days) in rats with an established cirrhosis. Cirrhosis was induced with nine doses of CCI⁴. Comparison of biopsies before and after treatment with IFNγ showed that the number of MFB present, identified by their α-smooth muscle actin immunoreactivity, was markedly reduced. Pressure-flow curves were constructed in isolated perfused liver preparations from IFNγ-treated and saline-treated cirrhotic rats and analysed to obtain the extrapolated zero-flow intercept (P⁰, an index of hepatic vascular distensibility) and the vasodilator-induced change in resistance at a flow rate of 1 mL/min per g (ΔR₁ an indication of the level of intrinsic vascular tone). In IFNγ-treated rats, portal venous pressure measured in vivo was significantly reduced compared with controls (11.9±1.2 vs 16.0 ± 0.5 mmHg, P < 0.05), P₀ was lower (2.03 ± 0.18 vs 2.87 ± 0.32 mmHg, P < 0.05) and ΔR₁ was decreased (0.39 ± 0.15 vs 1.02 ± 0.19 mmHg/mL per min per g, P < 0.05). The findings indicate that treatment with IFNγ is effective in reducing MFB density in established CCI₄-cirrhosis in the rat and results in a marked improvement in intrahepatic haemodynamics.     

Ventricular Tachycardia/Ventricular Fibrillation Ablation in the Setting of Ischemic Heart Disease

Recurrent ventricular tachycardia (VT) in the setting of coronary artery disease is frequently a life-threatening electrophysiologic emergency. Even in patients with an implantable defibrillator, recurrent VT is frequently accompanied by repeated and disabling shock therapy. Catheter ablative therapy offers the ability to provide immediate control of recurrent VT. Long-term elimination of VT should be anticipated in most patients. This article reviews the strategies, tools, techniques, and expected outcome for catheter ablation of stable and unstable ventricular arrhythmias in the setting ischemic heart disease.     

Electrophysiologic Spectrum of Atrioventricular Nodal Behavior in Patients with Atrioventricular Nodal Reentrant Tachycardia Undergoing Selective Fast or Slow Pathway Ablation

AV Nodal Behavior After Ablation. Introduction; The objective of this report is to delineate the atrioventricular (AV) nodal electrophysiologic behavior in patients undergoing fast or slow pathway ablation for control of their AV nodal reentrant tachycardia (AVNRT).
Methods and Results: One hundred sixteen consecutive patients with symptomatic AVNRT were included. Twenty-two patients underwent fast pathway ablation with complete abolition of AVNRT in all and development of complete AV block in five patients. Of 17 patients with intact AV conduction postablation, 12 had demonstrated antegrade dual pathway physiology during baseline study, which was maintained in three and lost in nine patients postablation. Two patients with successful fast pathway ablation developed uncommon AVNRT necessitating a slow pathway ablation. Twenty-one patients demonstrated both common and uncommon forms of AV nodal reentry during baseline study. The earliest site of atrial activation was close to the His-bundle recording site (anterior interatrial septum) during common variety and the coronary sinus ostium (posterior interatrial septum) during the uncommon AV nodal reentry in all 21 patients. Ninety-six patients underwent successful slow pathway ablation. Among these, the antegrade dual pathway physiology demonstrable during baseline study (60 patients) was maintained in 25 and lost in 35 patients postablation.
Conclusion: These data suggest that: (1) dual pathway physiology may persist after successful ablation, which might be a reflection of multiple reentrant pathways in patients with AVNRT: and (2) the retrograde pathways during common and uncommon AVNRT have anatomically separate atrial breakthroughs. These findings have important electrophysiologic implications regarding the prevailing concept of the AV nodal physiology in patients with AVNRT.