Sex ratio of multiple sclerosis in persons born from 1930 to 1979 and its relation to latitude in Norway

A remarkable increase in female to male ratio of multiple sclerosis (MS) is recognised in high incidence areas. Norway is a high-risk area for MS, spanning latitudes 58–71°N. We studied whether the sex ratio has changed over time and whether it differs by clinical phenotype or by latitude. Population-based epidemiological data and data from the Norwegian MS Registry on patients born from 1930 to 1979 were combined in this study. Place of birth was retrieved from the Norwegian Population Registry and information on clinical subtypes was obtained from the Norwegian MS Registry. The female to male ratio ranged from 1.7 to 2.7 (median 2.0) in 5,469 patients born in Norway, and increased slightly by 5-year blocks of year of birth (p = 0.043). The sex ratio was 2.6:1 in 825 patients born 1970–1979, which is significantly higher than in those born 1930–1969 (p < 0.001). In patients with relapsing remitting onset, the sex ratio was 2.4:1, while it was 1.1:1 in those with primary progressive disease. The sex ratio did not differ between the south, the middle and the north of the country. The overall sex ratio of MS is strongly determined by cases with relapsing remitting onset. We did not observe the remarkable increase in sex ratios of MS reported from other high-risk areas. The high sex ratio in the youngest birth cohorts may change as an increasing proportion of cases in this age group is being diagnosed. Sex ratio was not associated with latitude.     

Hyperosmotic perfusion of the beating rat heart and the role of the Na+/K+/2CI− co-transporter and the Na+/H+ exchanger

The aim of the present study was to investigate the role of the Na⁺/K⁺/2CI⁻ co-transporter and the Na⁺/H⁺ exchanger on contractile function and electrolyte regulation during hyperosmotic perfusion of the heart. Langendorff perfused rat hearts were subjected to hyperosmolal perfusion in 10-min intervals. Perfusates were made hyperosmotic by adding mannitol to the buffer (370, 450 and 600 mOsmol/kg H₂O). Cardiac contractile function was monitored with a balloon in the left ventricle (LV) coupled to a pressure transducer. Cardiac effluent was sampled repeatedly throughout and after hyperosmotic perfusion and analyzed for content of Na⁺, K⁺ and CI⁻. All three hyperosmotic perfusates initially reduced LV developed pressure (LVDP), but for 370 and 450 mOsmol/kg H₂, LVDP recovered to baseline within 4 min of perfusion. With 600 mOsmol/kg H₂, LVDP recovered slowly and was 50% below baseline after 10 min of hyperosmotic perfusion. Inhibition of the Na⁺/H⁺ exchanger with 5-(N-ethyl-N-isopropyl) amiloride (EIPA) and 3-methyl-sulfonyl-4-piperidinobenzoyl-guanidine methanesulfonate (HOE 694) abolished the recovery of LVDP to the 600 mOsmol/kg H₂ perfusate, whereas inhibition of the Na⁺/K⁺/2CI⁻ co-transporter had no impact on LVDP. Potassium was taken up by the heart during hyperosmotic perfusion and this uptake was significantly reduced with inhibition of the Na⁺/H⁺ exchanger. Intracellular pH was assessed with ³¹P magnetic resonance spectroscopy and hyperosmolality induced a significant alkalosis that was dependent upon the Na⁺/H⁺ exchanger. The rat heart responds to moderate elevations in osmolality with a transient reduction in contractile function, whereas an elevation of 300 mOsmol/kg H₂ persistently reduces contractile function. The Na⁺/H⁺ exchanger, but not the Na⁺/K⁺/2CI⁻ co-transporter, is of importance in contractile recovery and electrolyte regulation during hyperosmotic perfusion in the rat heart. Received: 10 December 1998, Returned for revision: 18 January 1999, Revision received: 1 July 1999, Accepted: 19 July 1999     

Combined effect of blood pressure and physical activity on cardiovascular mortality

BACKGROUND: High blood pressure increases cardiovascular mortality, but whether the effect is counteracted by physical activity is not clear. METHODS: The combined association of blood pressure and physical activity on cardiovascular mortality was assessed in a cohort of 30 597 women and 30 508 men, using standardized blood pressure measurements and information on usual frequency, duration, and intensity of physical exercise. RESULTS: During 16 years of follow-up, 1942 women and 2824 men with no history of cardiovascular disease or diabetes, who had never used blood pressure medication, died from cardiovascular causes. Cardiovascular mortality increased continuously with increasing blood pressure, and, at each blood pressure level, risk was higher in men and women with no physical activity compared with those who reported high physical activity. High activity combined with increasing pressure, however, yielded higher risk than high activity combined with normotensive pressure. Compared with the reference (systolic pressure 120-129 mmHg and high activity), the relative risk of cardiovascular death for systolic pressure of 140-159 mmHg combined with high activity was 1.21 (95% confidence interval, 0.97-1.52), compared with a relative risk of 1.73 (95% confidence interval, 1.37-2.19) in men with no activity. For women, the corresponding relative risks were 1.47 (95% confidence interval, 1.04-2.09) in the high activity group and 1.93 (95% confidence interval, 1.39-2.69) for no activity. The combined results for diastolic pressure and physical activity displayed similar patterns. CONCLUSIONS: The results support the hypothesis that cardiovascular health of individuals with moderate hypertension will benefit from regular physical exercise.     

Familial aggregation in Crohn's disease and ulcerative colitis in a Norwegian population-based cohort followed for ten years

Background and aimsTo explore the change in risk among 1st degree relatives of ulcerative colitis (UC) and Crohn's disease (CD) for development of concordant disease in an incidence cohort followed for ten years. Furthermore, we wanted to compare familial and sporadic cases regarding clinical characteristics and the course of the disease.MethodsThis population-based study included 421 patients with UC and 197 with CD enrolled from 1990 to 1994. Clinical characteristics and the number of 1st degree relatives of the patients were recorded continuously during ten years.ResultsAge at diagnosis in CD patients (OR = 0.95, 95% CI: 0.93–0.98) and cumulative relapse rate in UC patients (OR = 4.91, 95% CI = 1.16, 20.75) were significantly associated to familial clustering. Based on the calculated population prevalence of CD (262/100 000) and UC (505/100 000), the age-adjusted risk for development of concordant disease was 25.9 and 8.6 among siblings and parents of CD, respectively. In UC, the corresponding risks were 8.6 and 1.5. In the course of ten years the increase in risk was observed only among siblings (28%) and parents (97%) of UC, in contrast to no increase in CD. Moreover, the concordance for UC was high in three generations.ConclusionsOur study confirmed the importance of genetic influence on the development of CD. Within an observation period of ten years, the increased concordance and relapse rate in familial UC, might point to a larger genetic component in UC than previously suggested.