Habenular modulation of raphe indoleamine metabolism

Anatomical and neurophysiological findings have demonstrated neuronal connections between the diencephalic habenular nuclei and brain stem serotonergic raphe nuclei. Therefore we examined some neurochemical consequences of habenular lesions. Sixteen hours and one week after bilateral lesions serotonin metabolism (as reflected by concentrations of its metabolite, 5-hydroxyindoleacetic acid) was significantly increased in the dorsal but not the median raphe nuclei. Unilateral lesions produced a proportionally smaller augmentation. Motron locomotor activity was enhanced during the light and dark illumination phases in lesioned animals but only attained statistical significance during the day.     

ENVIRONMENTAL INFLUENCES ON NECTAR PRODUCTION IN MILKWEEDS (ASCLEPIAS SYRIACA AND A. EXALTATA)

Cross-comparisons of nectar production data are complicated because different workers use bags made of various materials to exclude animal visitors. Using clonal populations of Asclepias syriaca and A. exaltata in northern Virginia, we carefully measured the effects of four bagging treatments (bridal veil, pellon, paper, plastic) on microenvironment (temperature, relative humidity) and nectar production (volume, concentration, sucrose amount) over the course of a day. In general, bridal veil bags changed the microenvironment least relative to unbagged controls. Plastic bags resulted in higher temperatures and constantly higher relative humidities. Temperature and relative humidity were also elevated, though less dramatically, in paper and pellon bags. Under more humid conditions, flowers contained larger volumes of more dilute nectar. Therefore, researchers who wish to obtain nectar production data that reflect natural field conditions should use bridal veil, or a material with similar properties, to bag inflorescences. We also performed a watering experiment, involving the addition of the equivalent of a 10-cm rain to the A. syriaca plot. After watering, nectar volumes and sucrose amounts were increased approximately twofold.     

Leukoencephalomalacia in a white-tailed deer from North Carolina

Leukoencephalomalacia similar to equine leukoencephalomalacia occurred in a white-tailed deer (Odocoileus virginianus) from North Carolina. The deer was recumbent and stuporous when presented for examination. It was believed that the disease resulted from ingestion of moldy field corn, infected with Fusarium moniliforme.     

Relation of R Factor and Chromosomal β-Lactamase with the Periplasmic Space

The release of several R factor and chromosomal beta-lactamases by osmotic shock treatment was studied. It was found that those beta-lactamases with a molecular weight of about 20,000 were released, but those with a molecular weight of about 30,000 to 44,000 were not released during osmotic shock. This differential release did not depend on whether the structural genes were on the chromosome or on the genome of an R factor. The release or retention of the beta-lactamases appeared to be a characteristic of the enzyme rather than the host cell since the same results were obtained when the R factors were harbored by a variety of host bacteria. Studies with bacteria which produced more than one beta-lactamase showed that each enzyme reacted independently to the presence of other beta-lactamases produced by the host bacterium.     

Quantification of concentration changes in neonatal human cerebral oxidized cytochrome oxidase.

The oxygenation of cerebral cytochrome oxidase in vivo was investigated in eight newborn preterm infants. Near-infrared spectroscopy was used to quantify changes in the concentration of oxidized cytochrome oxidase ([CytO2]) observed during alterations in arterial oxygen saturation (SaO2) in the range of 85-99% and of carbon dioxide tension (PaCO2) in the range of 4.3-9.6 kPa. No relation was found between changes in SaO2 and [CytO2]. Alterations in PaCO2 were positively related both to changes in [CytO2] and total cerebral hemoglobin concentration [( Hb]t). The changes in [CytO2] ranged from 0.09 to 0.33 (median 0.21) mumol.l-1.kPa-1. The ratio [CytO2]/[Hb]t ranged from 0.06 to 0.12 (median 0.08). The relation of delta [CytO2] to the change in cerebral blood volume (delta CBV) was calculated: delta [CytO2]/delta CBV ranged from 0.09 to 0.18 (median 0.11) mumol/ml. These results define a fraction of cerebral cytochrome oxidase in the newborn infant that is oxidized after an increase in PaCO2 but demonstrate that a change in SaO2 in the range studied was not sufficient by itself to change [CytO2]. They differ from results of studies in adults; this may reflect significant differences between adult and neonatal brain.     

RNA pseudoknots. Stability and loop size requirements.

The effects of ionic conditions, loop size and loop sequence on the formation of pseudoknots by RNA oligonucleotides have been investigated using biochemical and biophysical methods. An oligonucleotide with the sequence 5' GCGAUUUCUGACCGCUUUUUUGUCAG 3' and oligonucleotides with variations in the sequences of the two loop regions, denoted by bold face type, were studied. Each sequence with the potential to form a pseudoknot can also form two stable hairpins. The pseudoknot structure is stabilized relative to the hairpins by addition of Mg2+. Even in the presence of Mg2+, the pseudoknots formed by the sequences investigated are only marginally more stable (1.5 to 2 kcal mol-1 in free energy at 37 degrees C) than either of the constituent hairpins. The pseudoknot structure is the stable conformation in the presence of Mg2+ when the first loop region is at least three nucleotides and the second is at least four nucleotides. Further deletion of nucleotides from the loop regions stabilizes possible hairpin structures relative to the pseudoknot and equilibria among secondary and tertiary structures result.     

Complement phenotypes in patients with psoriasis

Phenotype frequencies for the complement proteins C4A, C4B, Bf (factor B) and C3 were performed for 49 Caucasian patients with psoriasis. The C4*A6 allele was present in 26.6% of the patients as compared to 5.4% of healthy regional Caucasian controls, p less than 0.001, relative risk = 6.28. The C4*A6 allele is known to be in linkage disequilibrium with the HLA B17 allele and to produce a non-functional gene product when it occurs with the B17 allele. HLA B17 is known to be associated with psoriasis in many Caucasian populations. Additional findings in the present study were a significant reduction in the C4B*2 allele frequency, a non-significant increase in the Bf*F allele frequency and no difference for Bf or C3 phenotype frequencies in the patients with psoriasis as compared to the controls.     

Human monocytes selectively bind to cells expressing the tumorigenic phenotype

Summary The characteristics of the binding of human monocytes to tumor cells were studied by a newly developed microassay. First, we determined the kinetics and optimal conditions of the binding. Monocytes recognized and bound to tumor cells very rapidly within 10–20 min of cellular interaction. Binding was also more efficient at 37°C suggesting that active metabolism of monocytes is required. Second, we determined that selective binding of monocytes to cells with tumorigenic phenotypes occurs. For this purpose, lymphocytic leukemia cell lines versus normal lymphocytes, and tumorigenic versus nontumorigenic hybrids from the same parental lines were compared as the targets of the binding assay. In both cases, neoplastic cells were selectively bound by monocytes. Although tumor cells were bound rapidly and selectively by monocytes, initial recognition and binding did not necessarily lead to subsequent tumor cell lysis. This is based on the observation that some tumorigenic parental and hybrid lines were avidly bound by monocytes yet not subsequently killed in a cytotoxicity assay.This work was supported in part by a grant from the National Institutes of Health CA42992 and a grant from the Kleberg foundation Abbreviations used: [¹²⁵I]IdUrd [¹²⁵I]iododeoxyuridine; rIFN-, recombinant human interferon ; IL-1, interleukin 1; rTNF, recombinant human tumor necrosis factor