PubMed · 8641942
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E V Swihart. 1996-05-15. Practicing part time--a growing trend?. https://pubmed.ncbi.nlm.nih.gov/8641942/
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In mammalian species studied to date, the first-born neocortical cells normally form two layers, one above and one below the cortical plate, called the marginal zone (future layer 1) and the subplate. In primates and carnivores, many of these first-born cells die early in postnatal life. Whether this also occurs in rodents is highly controversial. In this study, we injected pregnant mice with bromodeoxyuridine on embryonic days (E) 11-14 to label the earliest generated neocortical cells, and examined their fates between birth and postnatal day 21. At birth, most cells born on embryonic day 11 were below the cortical plate, and a smaller proportion were above it. Very few of these cells remained by postnatal day 3 and there were none at any depth in the neocortex at older ages. At birth, the largest proportion of cells born on embryonic days 12 and 13 were in the subplate and smaller proportions were in the cortical plate and marginal zone. At older ages, almost all of these cells had disappeared from the marginal zone and from below the cortical plate, although some were retained in the cortical plate. The density of the remaining E12- and E13-born cells decreased more than could be explained by neocortical expansion alone. As a control, we studied cells born on embryonic day 14. These cells were restricted to the cortical plate at birth. By postnatal day 21, their density had decreased by an amount that could be explained by neocortical expansion alone. We conclude that, as in other species, many of the earliest generated cells of the murine neocortex die.
A total of 847 inbred Lewis rats of mixed sex were used in this pancreaticoduodenal (Pd) donor aging study. Pd grafts were taken from 9- to 12-month-old donors and transplanted into 3-month-old recipients (thus, the first generation Pd graft, or 1 Pd). After 9 to 12 months, the same Pd grafts were again harvested and transplanted into 3-month-old rats (thus the 2 Pd generation). This cycle was repeated to obtain the 3, 4, and 5 Pd series. Sequential transplantation was able to extend the Pd grafts' mean survival time to 32 months for fourteen 4 Pd grafts, and to 39.2 months for four 5 Pd grafts (the longest lived graft survived for 42 months). The pancreas and duodenal sections of the grafts remained normal throughout the entire study. However, the aortic sections of the grafts (which were harvested to include the superior mesenteric and celiac arteries) all exhibited moderate to massive atherosclerotic changes by the 5 Pd mean survival age of 39.2 months. Such histological changes commenced even before 21 months of Pd graft age in some animals, gradually progressing to dilation of the aorta (and subsequent narrowing of aortic tributaries), as well as formation of an eggshell-like inner membrane shielding the aortic intima, by 42 months. Such atherosclerotic changes precluded transplantations beyond the 5 Pd series.
OBJECTIVES: To describe functional outcomes of seriously III patients who survived 2 months after in-hospital cardiopulmonary resuscitation (CPR) and to identify patient and clinical characteristics associated with worse functional status after CPR. METHODS: Multicenter prospective observational analysis of 162 seriously ill hospitalized patients who survived 2 months after CPR. Analysis of clinical characteristics associated with worse functional outcome. RESULTS: Among 162 survivors of in-hospital CPR, 56% had the same or improved function and 44% had worse function at 2 months compared with functional status before CPR. Patients with worse function deteriorated by a mean of 3.9 activities of daily living and were less likely to survive to hospital discharge (P < .001) or to 6 months after study entry (P < .001). Worse functional outcome was associated with greater age and longer hospital stay before CPR. CONCLUSIONS: More than half of CPR survivors had preserved functional status 2 months after CPR. However, patients with worse function are profoundly disabled. In anticipation of possible severe disability after CPR, preferences for care in such health states should be discussed with patients before the need for CPR, particularly among older patients and those with long hospital stays.