Enkephalinergic involvement in periaqueductal gray control of hypothalamically elicited predatory attack in the cat.

The effects of central infusion of naloxone into the midbrain periaqueductal gray (PAG) upon predatory attack behavior in the cat were studied in 12 cats. Initially, quiet biting attack was elicited by electrical stimulation of sites within the lateral hypothalamus using monopolar electrodes. Then cannula-electrodes were implanted into sites within the PAG from which electrical stimulation facilitated or suppressed the attack response. Following identification of modulatory sites within the PAG, naloxone (1.0 micrograms/0.5 microliter) was microinjected into those sites and the effects upon hypothalamically elicited attack were assessed. At nine of twelve sites in the PAG where suppression was obtained, administration of naloxone served to block those effects. Similarly, at six of eight facilitatory sites within the PAG, naloxone also blocked the modulatory effects of PAG stimulation. However, vehicle (isotonic saline) alone did not alter the modulatory effects of PAG stimulation. Administration of DAME (250 ng/0.3 microliter) into PAG modulatory sites in four cats, two which facilitated and two that suppressed the attack response, reversed the effects of naloxone at these sites. These results demonstrate that opioid peptides within the PAG play a complex role in the expression of predatory attack behavior in the cat.     

Chemistry of maduramicin. II. Decarboxylation, abnormal ketalization and dehydration

The behavior of the free acid and ammonium salt of maduramicin towards heat and alcohols is examined. In refluxing lower alcohols the free acid material is decarboxylated. In addition a bisketal decarboxylated compound as well as an A-ring monoketal decarboxylated derivative are formed. Heating the ammonium salt of the ionophores in suspension in water, or dissolved in inert solvents such as heptane or xylene can cause decarboxylation as well as concomitant dehydration of the F-ring. Reaction of dansyl chloride with the free acid of maduramicin can cause dehydration of the B-ring under very mild conditions.     

Developing Conceptions of Chronic Disease: A Comparison of Disease Experience

We predicted that children's conceptions of various self-care behaviors and social relations would be related to their degree of experience with insulin dependent diabetes mellitus (IDDM). A total of 55 children were recruited for this study in three experience groups: children with IDDM (high experience), children having a sibling with IDDM (low experience), and normal healthy children (no experience). In line with our model, children with IDDM had a more developed and sophisticated understanding of concepts associated with disease management than did either siblings of children with diabetes or the comparison group; surprisingly, experience with the disease (children with IDDM) was associated with more complex conceptions of social relations as well.     

Ophthalmologic manifestations of genitourinary diseases

There are several urologic disorders which also involve the eye and orbit. We have compiled examples of these and reviewed the literature. Metastasis from genitourinary malignancy (including neuroblastoma), Wilms tumor, Reiter syndrome, tuberous sclerosis, von Hippel-Lindau disease, and oxalosis may all have ophthalmologic manifestations. Urologists need to be aware of these and obtain appropriate consultation in order to fully care for patients with these diseases.     

Variability of the pattern electroretinogram

Conflicting results have been obtained concerning the parametric properties of the pattern electroretinogram. These discrepancies may be due to the large amount of variability inherent in recording amplitudes. We have found the variability within a single stimulus condition to be so large (ranging from 30% to 67% of the mean value) that it could mask any underlying spatial frequency tuning. Changing the stimulus conditions failed to significantly reduce the observed variability, although changing recording conditions produced some reduction. The use of a narrower rejection band, a greater number of sweeps, and placement of the reference electrode on the ipsilateral ear (as opposed to the ipsilateral temple) combined to decrease variability of the pattern electroretinogram within a single recording session; however, intersession variability remained high. Therefore one must be careful in evaluating data from this technique, and caution is advised in its clinical use.     

The role of surgery in abdominal non-Hodgkin's lymphoma: experience from the Childrens Cancer Study Group.

To determine the appropriate role of surgical intervention in non-Hodgkin's lymphoma primary to the abdomen, we analyzed the effect of multiple prognostic determinants on event-free survival for patients entered into the CCG-551 study. Eighty-four patients were identified with abdominal lymphoma and of these adequate data for analysis was available on 68 (81%). Variables of interest included: extent of disease at diagnosis, completeness of resection, use of bowel resection, radiation to the primary site, and sex/age/race. The median age on study was 8 years; 79% of patients were white and 85% were male. Thirty-three patients (49%) presented with localized disease. Laparotomy was performed in 67 children (99%) with complete gross resection in 28 (42%). Of the 10 reported surgical complications, 8 occurred in those with extensive disease who were incompletely resected. Radiation to the primary site was given in 60% of patients with median dose of 2,000 cGy. Analysis was performed both for the overall group and for the subgroup receiving optimal chemotherapy for histopathology. Variables with significant predictive effect on event-free survival in univariate analysis included extent of disease (P less than or equal to .001), complete resection (P less than or equal to .002), and use of bowel resection (P less than or equal to .004). However, in multivariate analysis, only extent of disease was an independent predictor of outcome. The data support a role for complete operative excision of localized lymphomas especially when accomplished with bowel resection. Aggressive attempts at debulking extensive retroperitoneal or mesenteric lymphomas are contraindicated.     

Bone marrow stromal cell bioactivation and detoxification of the benzene metabolite hydroquinone: comparison of macrophages and fibroblastoid cells

Bone marrow stroma consists predominately of two cell types, macrophages and fibroblastoid stromal cells, which regulate the growth and differentiation of myelopoietic cells via the production of growth factors. We have previously shown that macrophages are more sensitive than fibroblastoid stromal cells (LTF cells) to the toxic effects of the benzene metabolite hydroquinone. In this study, the role of selective bioactivation and/or deactivation in the macrophage-selective effects of hydroquinone was examined. LTF and macrophage cultures were incubated with 10 microM [14C]hydroquinone to examine differential bioactivation. After 24 hr, the amount of 14C covalently bound to acid-insoluble macromolecules was determined. Macrophages had 16-fold higher levels of macromolecule-associated 14C than did LTF cells. Additional experiments revealed that hydroquinone bioactivation to covalent-binding species was hydrogen peroxide dependent in macrophage homogenates. Covalent binding in companion LTF homogenates was minimal, even in the presence of excess hydrogen peroxide. These data suggest that a peroxidative event was responsible for bioactivation in macrophages and, in agreement with this, macrophages contained detectable peroxidase activity whereas LTF cells did not. Bioactivation of [14C]hydroquinone to protein-binding species by peroxidase was confirmed utilizing purified human myeloperoxidase in the presence of hydrogen peroxide and ovalbumin as a protein source. High performance liquid chromatographic analysis of incubations containing purified myeloperoxidase, hydroquinone, and hydrogen peroxide showed that greater than 90% of hydroquinone was removed and could be detected stoichometrically as 1,4-benzoquinone. 1,4-Benzoquinone was confirmed as a reactive metabolite formed from hydroquinone in macrophage incubations using excess GSH and trapping the reactive quinone as its GSH conjugate, which was measured by high performance liquid chromatography with electrochemical detection. The activity of DT-diaphorase, a quinone reductase that has been invoked as a protective mechanism in quinone-induced toxicity, was 4-fold higher in LTF cells than macrophages. These data suggest that the macrophage-selective toxicity of hydroquinone results from higher levels of peroxidase-mediated bioactivation and/or lower levels of DT-diaphorase-mediated detoxification.