Children in single-father families in demographic perspective

The purpose of this article is to examine single-parent families headed by fathers. "We use specially constructed child files from the 1960-1990 Public Use Microdata Samples data from the Census of Population to address two general questions: (a) To what extent has both the likelihood and the demographic characteristics of these families changed over time? (b) What are the consequences for children of living in different kinds of father-only families? We find that single-father families are comparatively rare, but increasing rapidly, especially since 1980. Increasingly, these families are formed by fathers who are young, never married, with low incomes, and fewer children. Analysis of the 1990 data reveals wide diversity in living arrangements among children in single-father families. Furthermore, the social capital of children's fathers, the availability of adults, and children's economic well-being vary markedly across these types of families."     

3H-Apomorphine interactions with dopamine receptors in calf brain

3H-apomorphine binds to membranes from areas of the corpus striatum and limbic system of calf brain saturable and with a drug specificity indicating that it labels dopamine receptors. In terms of drug specificity, log-logit displacement curve slopes and number of binding sites, 3H-apomorphine interacts with receptors in a manner more like 3H-dopamine than 3H-haloperidol. These properties of 3H-apomorphine binding are those of an apparently "pure" agonist in contrast to the partial agonist effects of apomorphine upon the dopamine-sensitive adenylate cyclase.     

The use of a computer to select optimized conditions for high-performance liquid chromatography separation.

Computer simulation allows the convenient prediction and optimization of HPLC separation as a function of various separation conditions. The use of retention and bandwidth relationships that have been validated for a broad range of chromatographic systems minimizes the number of experimental runs needed, especially for the new technique of restricted multi-parameter optimization. The chromatographer is free to use these procedures in a trial-and-error mode, or alternatively use can be made of resolution maps and other data summaries. "Gridding" experiments, based on the automated collection of chromatographic data, can be used to supplement predictions obtained from computer simulation.     

Protection by cyclosporin A of cultured hepatocytes from the toxic consequences of the loss of mitochondrial energization produced by 1-methyl-4-phenylpyridinium.

Cyclosporin A prevented the killing of cultured rat hepatocytes by 1-methyl-4-phenylpyridinium (MPP+). However, in the presence of both cyclosporin and atractyloside, there was no protection. Cyclosporin had no effect on the depletion of ATP or the loss of mitochondrial energization by MPP+. Cyclosporin, however, did prevent the increase in the molecular order of hepatocyte membranes produced by MPP+. These data suggest that mitochondrial de-energization produced by MPP+ is accompanied by a "permeability transition" analogous to that which occurs in vitro in the presence of calcium. By preventing this transition, cyclosporin protects the cells. By antagonizing this action of cyclosporin, atractyloside restores the cell killing. The mitochondrial transition is causally linked to cell killing by a mechanism that increases the molecular order of the hepatocyte plasma membrane.     

A novel neuronal messenger molecule in brain: the free radical, nitric oxide.

Understanding of the organization and function of a newly identified neuronal messenger molecule, nitric oxide, has progressed rapidly. Nitric oxide synthase has been purified and molecularly cloned from brain. Its localization is exclusively neuronal and endothelial. The catalytic activity of nitric oxide synthase accounts for the NADPH diaphorase staining of neurons that are uniquely resistant to toxic insults and neurodegenerative disorders. Nitric oxide has diverse functions. In platelets it inhibits their aggregation, in macrophages it mediates cytotoxicity, and in blood vessels it acts as a vasodilator. In the nervous system nitric oxide may be the retrograde transmitter in long-term potentiation. It is the "neurotransmitter" of cerebral vasodilator nerves and the inhibitory "neurotransmitter" of the motor neurons of the intestines. Nitric oxide in situations of excessive production may function as a neurotoxin, suggesting a role for nitric oxide in neurodegenerative disorders.     

Simulation of blood flow in microgravity.

Knowledge of venous, capillary, and arterial blood flow in microgravity is required to modify hemostatic techniques for control of bleeding in traumatic injuries or surgical procedures in space. To simulate human arterial, venous, and capillary bleeding, fresh whole bovine blood was injected by two operators at calculated flow rates (3.5, 7, and 14 mL for venous and 14 and 28 mL for arterial) in 10 seconds with empirical controls in a lucent glove box during zero gravity parabolic flight on NASA's KC-135 aircraft. A pig's foot was used to mimic capillary bleeding. Hemostasis with sponges and laerdal suction was evaluated by video and still photography. Evaluations of the arterial and venous bleeding were conducted at 3 rates x 3 parabolas, and capillary bleeding was evaluated with 5 parabolas x 2 methods (pig's foot and sponge). Influenced by surface tension, the slow venous bleeding coated syringe surfaces and formed a dome over the skin laceration bleeding site. Arterial and venous bleeders broke into uniform spheres with low-velocity spheres bouncing off an absorbent pad and suction tip. Conventional dabbing with gauze fragmented blood into small spheres. Capillary oozing was better controlled by "wicking" up blood with gauze. Repeated arterial bleeding opacified the glove box wall. This stimulation demonstrated unique characteristics of extracorporeal blood flow and inadequacies of common methods of hemostasis in microgravity.     

Abnormalities of cerebral oxidative metabolism in animal models of Parkinson disease

Abnormalities of cerebral oxidative metabolism were investigated in "animal models" of Parkinson disease by in situ optical measurements of local cerebral blood volume and cytochrome oxidase redox shifts in rats two weeks after unilateral 6-hydroxydopamine lesions of the substantia nigra with or without interruption of ascending noradrenergic pathways. The data demonstrate oxidative metabolic dysfunction of ipsilateral cerebral hemispheres caused by lesions that involve both dopaminergic and noradrenergic systems but not when dopaminergic neurons only are affected. We speculate that the dementia of Parkinson disease may be more prevalent when degeneration of catecholaminergic systems is widespread and not restricted to the dopaminergic system.     

Inability to demonstrate hydroxylation of tyrosine by murine melanoma "tyrosinase" (L-DOPA oxidase), using the tritiated water assay technique.

Validity of the tritiated water assay technique for tyrosine hydroxylase activity as a qualitative method was demonstrated with mushroom tyrosinase. Using this method, isolated murine melanoma "tyrosinase" (L-dopa oxidase) showed no tyrosine hydroxylase activity. This finding supports previous studies in our laboratory which used a variety of histochemical and biochemical methods. The nonenzymatic production of tritiated water caused by tritium exchange with hydrogen peroxide complicates the use of the tritiated water assay technique with crude systems, since hydrogen peroxide is generated by a variety of oxidase reactions. For this reason, previous studies using the tritiated water assay technique with crude systems are ambiguous.