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At least 1,531 records · Page 85Linked to original sources
PubMed1979

Recent advances in programmable pacemakers. Consideration of advantages, longevity and future expectations.

The important electrical characteristics of conventional ventricular demand pacemakers currently widely employed are unable to be altered by noninvasive means after their implantation. However, a number of domestic pacemaker manufacturers have started to introduce a new modality for atraumatic modulation of these devices, the fully programmable pacemaker system, whereby the several variables regulating pacemaker operation may be optimized on an individual basis according to need. Such programmable pacemaker functions which can be varied include rate, energy output, refractory period and sensing threshold. The indications, significance and mechanisms for control of the various function programming are delineated for physician understanding at the present time.

Arrhythmias, Cardiac↗
PubMed1987

Age-related reductions in brain cholinergic and dopaminergic indices in two rat strains differing in longevity.

We have recently reported that inbred Wistar-Kyoto rats which are highly reactive to stressful stimuli, have a much shorter mean life-span (21.5) compared to the less reactive Brown-Norway rats (31.0 +/- 4.5 months). In the present study we found a reduction in forebrain cholinergic neurotransmission indices in 24-month-old Wistar-Kyotos but not in Brown-Norways as compared to their respective young (3-month-old) counterparts. Also only in Wistar-Kyotos dopamine uptake was reduced in the aged striatum, but in the septum it remained unchanged in both strains. In Brown-Norways, age-related changes were observed only in choline acetyltransferase activity and only in brain regions known to contain mainly cholinergic nerve cell bodies. We conclude that at 24 months of age, reductions in brain cholinergic and dopaminergic neurotransmission are more prominent in the highly stress-reactive and shorter-lived Wistar-Kyoto strain, and may be genetically determined.

Acetylcholine↗
PubMed1986

Ultrasound monitored hepatic cryosurgery: longevity study on an animal model.

Ultrasound imaging has been proposed to monitor the amount of frozen tissue during hepatic cryosurgery of primary and metastatic tumors. In this follow-up study, a cryolesion was produced in an adult pig under ultrasound monitoring. The animal was allowed to recuperate for 3 days before being sacrificed. Pathologic and histologic evaluation showed extremely close correlation with the ultrasound image. The necrotic region was clearly observable in the sonogram after 3 days. Ultrasonography can accurately represent the extent of the cryolesion both during as well as following cryosurgery.

Animals↗
PubMed1994

Apolipoprotein E and B polymorphisms--longevity factors assessed in nonagenarians.

To test if the prevalence of genetic risk factors for coronary heart disease (CHD) is low in individuals who have reached an extremely old age, the allele frequencies of apolipoprotein E (apo E) and B (apo B) polymorphisms and plasma lipoprotein(a) levels were investigated in nonagenarians and in younger control groups. The frequency of the epsilon 4 allele of apo E was significantly lower in the nonagenarians than in the middle-aged and young adults (P < 0.05). Also, the frequency of EcoRI allele R- of apo B was low in the nonagenarians, whereas the allele frequency for the XbaI polymorphism of apo B and plasma lipoprotein(a) concentrations did not differ between the nonagenarians and the younger groups. These findings strongly suggest that the presence of these potential genetic risk factors for CHD, namely the epsilon 4 allele of apo E and the R- allele of apo B, decreases the probability of an individual reaching an extremely old age.

Adult↗