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Biomedical subjects

H Kennedy

Publications and source records attributed to H Kennedy.

130 records · Page 8Linked to original sources
PubMedDate not supplied

Predictors of ventricular fibrillation or cardiac arrest in patients hospitalized for acute myocardial infarction.

A community-wide study of patients hospitalized with acute myocardial infarction in metropolitan Baltimore was conducted to examine socio-demographic and clinical characteristics in association with ventricular fibrillation and cardiac arrest (VF/CA). Multivariate analyses revealed that variables significantly associated with occurrence of VF/CA included older age (60 years or older), male sex, and a history of cigarette smoking. These factors allow the identification of subgroups of patients hospitalized with acute myocardial infarction at high risk for the subsequent development of VF/CA, in whom prophylactic therapy and close surveillance are especially recommended.

Female↗
PubMedDate not supplied

Cortical specification of mice and men.

The developmental basis for the localization of function in the mammalian cortex remains a controversial issue. The newly formed rodent cortex displays a considerable uniformity in terms of its connectivity. This contrasts with the primate, where even the first formed connections can show a high degree of areal specificity. An important clue to understanding these species differences can be obtained by examining how and when the sensory periphery exerts its organizing influence on the developing cortex. In rodents the developmental timetable ensures that the organizational control of the periphery persists late in development, when neurons are forming their first connections. By contrast, in primates the late onset and prolonged duration of corticogenesis result in the periphery being able to exert its influence much earlier, during the phase of precursor proliferation. Differences and similarities between primate and rodent corticogenesis are highly informative. In rodents, recent results with molecular markers show that regional differences in developmental potential exist in the cerebral cortex before innervation from the periphery. Similar findings are predicted in primates. It is to be expected that a more complete understanding of the rules governing the emergence of distinct cortical areas will come from resolving how afferent specification acts within the confines of such regional specializations.

Animals↗
PubMedDate not supplied

Developmental remodeling of primate visual cortical pathways.

The pre- and postnatal developmental changes of the cortical afferents to area 17 were studied in the macaque monkey. Paired injections of the retrograde tracers fast blue and diamidino yellow were made in area 17. Quantitative techniques were used to examine the spatial patterns of labeling in three distinct locations of the extrastriate cortex that correspond to known visual areas. In the adult, each cortical region has a characteristic laminar distribution. In the fetus the proportion of supragranular layer neurons in all cortical regions was much higher than in the adult. The present study shows that despite the very high levels of labeled supragranular layer neurons, there is some early areal specialization so that the adult configuration does not emerge from a uniform distribution. The developmental decline in the proportion of labeled supragranular neurons is complete by 1 month after birth. Each injection of tracer gave rise in each cortical area to dense labeling in a restricted region (projection zone). Areal measurements of projection zones in the supra- and infragranular layers showed that the developmental decrease in the proportion of labeled supragranular layer neurons is accompanied by a relative change of the dimensions of supra- and infragranular projection zones: the supragranular projection zone in the fetus is larger than the infragranular projection zone and vice versa in the adult. In the fetus, the two projection zones corresponding to each of the two tracers overlap in the supragranular layers whereas they are largely separated in the infragranular layers. During development there is a progressive decrease in the overlap of the supragranular projection zones and an increase in the overlap in the infragranular layers. Again, the adult configuration is achieved 1 month after birth. This developmental inversion of the areal dimensions of the projection zones in supra- and infragranular layers is accompanied by a drastic decrease in the proportion of double-labeled neurons located in supragranular layers. These results clearly show that early in development, axonal projections to area V1 are modified in very different ways according to whether they originate from supra- or infragranular layers. This developmental process lasts for about 80 d. These findings show that in the primate there is a prolonged remodeling of axonal projections that is a highly characteristic feature of this species.

Amidines↗