Migratory paths and phenotypic choices of clonally related cells in the avian optic tectum

We used retrovirus-mediated gene transfer to study the migration of clonally related cells in the developing chicken optic tectum. Clonal cohorts initially form radial arrays in the ventricular zone (approximately E5), but eventually divide into three separate migratory streams. In the first migration, a minor population of cells migrates tangentially along axon fascicles in medio-laterally directed files (approximately E6-E7); these eventually differentiate into multipolar efferent cells. After E7, the majority of cells in each clone migrate radially along fascicles of radial glia to form the tectal plate, wherein they differentiate into neurons and astrocytes. Around E9, a set of small cells leaves the radial arrays in superficial layers to form a second tangential migration; at least some of these differentiate into astrocytes. Thus, as the tectum develops, cells derived from a single multipotential precursor migrate along three separate pathways, follow separate guidance cues, and adopt distinct phenotypes.

Migratory patterns of clonally related cells in the developing central nervous system

Neurons and glioblasts that arise in the ventricular zone migrate to form discrete nuclei and laminae as the central nervous system develops. By stably labeling precursor cells in the ventricular zone, pathways taken by different cells within an individual clone can be described. We have used recombinant retroviruses to label precursor cells with a heritable marker, the E. coli lacZ gene; clones of lacZ-positive cells are later mapped histochemically. Here we review results from three regions of the chicken central nervous system--the optic tectum, spinal cord, and forebrain--and compare them with previous results from mammalian cortex and other regions of the vertebrate CNS. In particular, we consider the relationship between migratory patterns and functional organization, the existence of multiple cellular sources of migratory guidance, and the issue of whether a cell's choice of migratory pathway influences its ultimate phenotype.

Can total parenteral nutrition reverse hypoalbuminemia in oncology patients?

To determine if hypoalbuminemia is a consequence of protein-energy malnutrition rather than an associated feature of cancer, we reviewed results when vigorous nutritional support was given to 13 men and 9 women who had solid tumors (head and neck [10], gastrointestinal [8], other [4]) and an initial serum albumin less than 3.5 g/dl. Patients had received a minimum of 21 days of nutritional support with total parenteral nutrition (TPN) supplying an average daily energy intake of at least 1.5 x basal energy expenditure (BEE). The TPN was started at a dosage commensurate with the patient's estimated postoperative caloric requirements, and patients had received an average of 2358 kcal/day (1.97 x BEE) and 1.54 g of protein/kg of body weight. Patient body weights increased by an average of 2.75 kg during the 21 days of TPN, but there was no statistically significant change in serum albumin, suggesting that factors other than malnutrition were primarily responsible for the hypoalbuminemia. Although TPN is useful as an adjunct in patients with cancer, it may not reverse the hypoalbuminemia commonly seen in this population.

Neurons and glia arise from a common progenitor in chicken optic tectum: demonstration with two retroviruses and cell type-specific antibodies

We used a recombinant retrovirus to study cell lineage in the chicken optic tectum. The virus inserts the Escherichia coli lacZ (beta-galactosidase) gene into the genome of an infected cell; a histochemical stain marks the progeny of infected cells with a blue precipitate. We had previously shown that individual clones frequently contain diverse neuronal types. Now we asked whether individual clones contain glia as well as neurons. To this end, we constructed a virus in which lacZ is fused to a nuclear localization signal sequence from the simian virus 40 large tumor antigen. Cells infected with this virus are marked with blue nuclei instead of blue somata. In embryos injected with a mixture of the two retroviruses, individual clusters contained cells with only one label type (nuclear or cytoplasmic), thus verifying that clusters of cells were clones. Furthermore, it was possible to immunostain the somata of cells that had blue nuclei, whereas the blue cytoplasmic precipitate hampered immunostaining. Together, these methods allowed us to show that some clones contained neurons (neurofilament-positive) and two types of glia (glutamine synthetase-positive and glial fibrillary acidic protein-positive). This result demonstrates the existence of a common progenitor for neurons and glia in optic tectum.

Nutrition and dementia

The nutritional consequences of dementia and the role of diet in the etiology, treatment, and prevention of dementia are the subjects of this review. The major cause of dementia is Alzheimer's disease. Although it has been suggested that aluminum intake may cause this disease, the bulk of scientific evidence suggests that this is unlikely. Dietary supplements of choline and lecithin have been used to treat Alzheimer's disease but are ineffective. Alzheimer's disease patients are at risk of developing protein-energy malnutrition because of poor food intake and increased energy requirements. The second most common cause of dementia is multi-infarct dementia, caused by multiple strokes. Diet may play a role in the prevention of this form of dementia through effects on blood pressure and other risk factors. Control of risk factors may also prevent further progression of the dementia. Patients with multi-infarct dementia often have dysphagia. The third most common cause of dementia appears to be excessive alcohol intake, due both to the direct neurotoxic effects of alcohol and to the effects of alcohol on nutritional status. Alcoholic dementia may be at least partially reversible with abstinence and good nutrition. Other causes are vitamin B-12 and folate deficiencies; these are reversible dementias. In all types of dementia, adequate nutrition may improve physical well-being, help maximize the patient's functioning, and improve the quality of life.

Nutritional aspects of psychiatric disorders

As most diet therapy texts provide little information about psychiatric illnesses and their treatment, this article is intended as a brief introduction for dietitians. Several psychiatric illnesses, including schizophrenia, mood disorders, eating disorders, and substance abuse, may adversely affect food intake and nutritional status. The drugs used to treat those disorders similarly have effects on appetite and gastrointestinal function and interact with food and nutrients. Antipsychotics, antidepressants, and monoamine oxidase inhibitors (MAOIs) cause dry mouth, constipation, and weight gain. Lithium may cause nausea, vomiting, diarrhea, polydipsia, and weight gain. MAOIs have well-known interactions with foods containing tyramine. Lithium interacts with dietary sodium and caffeine; decreasing dietary intakes of those substances may produce lithium toxicity. Despite claims to the contrary, major psychiatric illnesses cannot be cured by nutritional therapies alone. Dietitians can, however, play an important role as part of a multidisciplinary team in the treatment of patients with psychiatric illness. Such a role includes nutrition assessment and monitoring, nutrition interventions, patient and staff education, and some forms of psychotherapy, including supportive and behavioral therapies for patients with eating disorders.

Assaults by patients against psychiatric residents at a public psychiatric hospital

Forty-six psychiatric residents at a county hospital were surveyed about their exposure to patient violence. The overall incidence of assaults was 2.8 per 100 resident-months at risk. Statistically significant differences were found in the rates of assaults on different services; the rates were highest on the child and adolescent services and lowest on the adult outpatient service. Most of the assaults were committed by psychotic, male, young adults, but only male sex and age less than 13 years were statistically associated with increased risk of assaultiveness. Diagnosis and race were not associated with assaultiveness. The usual means of attack involved hitting or kicking and seldom resulted in serious injury.

Radial arrangement of clonally related cells in the chicken optic tectum: lineage analysis with a recombinant retrovirus

A recently described method for lineage analysis in rodents uses a recombinant retrovirus to insert a foreign gene into the genome of a precursor cell; the gene's product is later detected histochemically in the infected cell's progeny. We have adapted this method for use in chicken embryos and used it to study the disposition of clonally related cells in the optic tectum. We report that descendants of a single precursor form narrow, radially oriented columns that span the thickness of the developing tectum. Analysis of embryos injected with virus at different stages suggests a developmental scheme in which early-born progeny are displaced laterally, late-born progeny are displaced radially, and cell mixing is limited. Many clones remain radially arrayed as laminae form and contribute neurons of diverse types of several laminae. In light of previous studies showing physiological relationships among vertically arrayed neurons, our results suggest that neurons descended from a single precursor are richly interconnected and functionally related.

Androgen regulation of muscle fiber type in the sexually dimorphic larynx of Xenopus laevis

We used histochemical techniques [assays for adenine triphosphatase (ATPase) and succinate dehydrogenase (SDHase) activity] to identify muscle fiber types in the larynx of Xenopus laevis. Male muscle is made up of one fiber type, medium-sized fibers (approximately 9 microns2) that stain lightly for acid-stable ATPase and intensely for SDHase activity. In contrast, the female has 3 fiber types: small fibers (approximately 6 microns2) that stain intensely for ATPase and SDHase, medium-sized fibers (approximately 13 microns2) with moderate staining for ATPase and dark staining for SDHase, and large fibers (approximately 15 microns2) with little SDHase or ATPase activity. Long-term castration (6 months) has no effect on histochemical staining of adult male fibers. Long-term testosterone treatment (5 months) increases the proportion of medium-sized, moderately staining fibers in adult females, and reduces the proportion of both the small, darkly staining fibers and the large, lightly staining fibers. At metamorphosis, both males and females have 3 fiber types whose ATPase activity is similar to that of the adult female. However, no SDHase activity is observed. Treatment of juveniles for 3 weeks with testosterone results in nearly complete masculinization of muscle fibers, as judged by increased cross-sectional area, homogeneous ATPase staining, and a marked increase in SDHase activity. Thus, juvenile muscle is considerably more responsive to testosterone than is adult female muscle. We propose that the uniform metabolic properties of male laryngeal muscle contribute to the production of the rapid (66 Hz) mate call vocalizations characteristic of this species. Further, our results suggest that androgens direct the masculinization of laryngeal muscle fibers during postmetamorphic development.

Vitamin supplement use in a Southern California retirement community

Vitamin supplement were taken regularly by 62% of men and 69% of women surveyed in a Southern California retirement community. Supplement use was associated with more frequent use of health screening procedures and with several other health-related habits. A substantial proportion of residents consumed high levels of vitamins C and E, and 3.2% consumed potentially toxic doses of vitamin A.

Vitamin A and cancer incidence in a retirement community

The use of vitamin A supplements and the risk of cancer was examined in a cohort of 11,888 residents of a retirement community near Los Angeles, California. After 2 1/2 years of follow-up, 445 incident cancers occurred in 435 of the study participants. Overall, the relative risk of cancer for supplement users versus nonusers was 1.0. In a subset of 32 randomly selected individuals, the 14 supplement users had a significantly higher mean serum retinol level (86 micrograms/dl) than did the 18 nonusers (74 micrograms/dl).

Assessment of three brief methods of estimation of vitamin A and C intakes for a prospective study of cancer: comparison with dietary history

Three methods of estimating vitamin A and C intakes from food frequency data obtained in June 1981 were compared with estimates obtained from dietary histories taken in September 1982, in 50 elderly residents of a Southern California retirement community. The first method of estimating vitamin A and C intakes (Af and Cf) was to add the products of the frequency of use of foods and the vitamin content of an average serving. The second method of estimating the intakes of these vitamins (Ai and Ci) was to develop an index based on the sum of frequencies of consumption of foods rich in these vitamins. This was then converted to absolute amounts using a regression equation. The third method (Ar and Cr) was to use stepwise multiple regression with the estimated intakes from the history (Ah and Ch) as dependent variables and to develop an equation with a small number of foods as the independent variables. When intakes from food alone were examined, the Spearman correlations between Ah and Af, Ai, and Ar, respectively, were 0.03, 0.16, and 0.43; the correlations between Ch and Cf, Ci, and Cr were 0.29, 0.36, and 0.38. When supplemental vitamin intakes were included, the correlations were between 0.35 and 0.44 for vitamin A and between 0.62 and 0.64 for vitamin C. The results demonstrated the importance of including the contribution of supplemental vitamins in estimating total vitamin A and C intake and suggested that the index and regression approaches may be superior to Af and Cf for estimating dietary vitamin intakes from food frequency questionnaires.

Dietary intake and nutrient supplement use in a Southern California retirement community

Dietary histories and information concerning the use of nutritional supplements were obtained from 51 randomly selected residents of an Orange County, CA, retirement community. The nutrients for which dietary intakes were most apt to fall below 100% of the 1980 Recommended Dietary Allowance were: calcium, in both sexes; energy, in males; and iron, thiamin, riboflavin, and niacin in females. With the exception of calcium, few subjects had intakes below two-thirds of the Recommended Dietary Allowances. These findings are similar to those reported in previous dietary surveys of the elderly. Vitamin and mineral supplements were consumed by 72% of the subjects; such consumption was unrelated to dietary intake. Supplemental vitamin C was consumed by 67% of the subjects in amounts ranging from 30 to 5200 mg daily; supplemental vitamin E was taken by 51%, with amounts ranging from 8 to 1000 IU daily. Supplement use by this population is one of the highest reported among the elderly, an effect that may result from the affluence of the community, its geographic location, and from a high level of nutritional consciousness among its residents.