The periaqueductal gray matter mediates opiate-induced immunosuppression

The periaqueductal gray matter of the mesencephalon (PAG) subserves a variety of diverse autonomic functions and also appears to be a site for opiate action in the induction of immunosuppression. Microinjections of morphine into the PAG, but not into other opiate receptor-containing neuroanatomical sites, result in a rapid suppression of natural killer (NK) cell activity. The NK cell suppression can be blocked by prior peripheral administration of the opiate antagonist naltrexone. These findings demonstrate that certain central actions of opiates that produce changes in NK cell function are mediated through opiate receptors in the PAG and identify a brain region involved in opiate regulation of immune function.     

Efficacy of murine malaria sporozoite vaccines: implications for human vaccine development

As part of a study of potential vaccines against malaria, the protective efficacy of sporozoite subunit vaccines was determined by using the Plasmodium berghei murine malaria model. Mice were immunized with recombinant DNA-produced or synthetic peptide-carrier subunit vaccines derived from the repetitive epitopes of the Plasmodium berghei circumsporozoite gene, or with radiation-attenuated sporozoites. Immunization with subunit vaccines elicited humoral responses that were equivalent to or greater than those elicited by irradiated sporozoites, yet the protection against sporozoite challenge induced by either of the subunit vaccines was far less than that achieved by immunization with attenuated sporozoites. Passive and adoptive transfer studies demonstrated that subunit vaccines elicited predominantly antibody-mediated protection that was easily overcome whereas irradiated sporozoites induced potent cell-mediated immunity that protected against high challenge doses of sporozoites. These studies indicate that new strategies designed to induce cellular immunity will be required for efficacious sporozoite vaccines.     

Methionine and leucine enkephalin in rat neurohypophysis: different responses to osmotic stimuli and T2 toxin

Specific radioimmunoassays were used to measure the effects of hypertonic saline (salt loading), water deprivation, and trichothecene mycotoxin (T2 toxin) on the content of methionine enkephalin (ME), leucine enkephalin (LE), alpha-neoendorphin, dynorphin A, dynorphin B, vasopressin, and oxytocin in the rat posterior pituitary. Concentrations of vasopressin and oxytocin decreased in response to both osmotic stimuli and treatment with T2 toxin, but the decrease was greater with osmotic stimulations. Similarly, concentrations of LE and dynorphin-related peptides declined after salt loading and water deprivation; LE concentrations also decreased after treatment with T2 toxin. The concentration of ME decreased after water deprivation, did not change after salt loading, and increased after T2 toxin treatment. The differentiating effects of these stimuli on the content of immunoreactive LE and ME are consistent with the hypothesis that LE and ME may be localized in separate populations of nerve endings with different roles in the posterior pituitary.     

Intercellular spaces enhance potato tuber elasticity

Summary The intercellular volume within tuber tissue increases with tuber maturation. At the same time, both tuber injury after mechanical load and lentical perforation after water uptake by tubers in wet peat decreases. The degree of tuber injury is correlated with intercellular space (r=−0.667,n=16) and with water saturation of tissue (r=0.697,n=16). The tubers lose water during storage. In wet soil wilted tubers take up significantly higher amounts of water than turgid tubers, and lenticel perforation is much more frequent. Tuber maturation in autumn and low water loss during storage enhance the cushioning effect of the intercellular gas volume of tuber tissue against outside mechanical load and internal tension after water uptake.     

Mineral binding capacity of dephytinized insoluble fiber from extruded wheat,oat and rice brans

Insoluble fiber fractions from raw and extruded oat, rice and wheat brans were isolated and phytate removed. In vitro mineral binding studies were performed utilizing copper (Cu²⁺), calcium (Ca²⁺) and zinc (Zn²⁺) ions, which were added individually to enzymatically treated (Prosky et al., 1985), acid washed insoluble fiber residues from oat, rice and wheat brans. The enzymatic digestion step with alpha-amylase, protease and amyloglucosidase served to remove protein and starch from the samples. Mineral binding studies were performed on the insoluble fiber residue. Mineral content was determined by flame atomic absorption spectroscopy. Raw brans served as controls. A twin-screw extruder Model DNDG-62/20D, manufactured by Bühlerag (CH-9240, Uzwil, Switzerland) was utilized. The objectives of the study were to determine the total Cu²⁺, Ca²⁺ and Zn²⁺binding capacity of the dephytinized insoluble fiber from each bran; and to determine if extrusion screw speed affected the brans' insoluble fiber mineral binding capacity. Although dephytinized, the brans' insoluble fiber fraction bound Cu²⁺, Ca²⁺ and Zn²⁺ions. Oat bran bound more Cu²⁺, Ca²⁺ and Zn²⁺ than wheat bran, which bound more than rice bran. Extrusion processing did not affect the brans' insoluble fiber binding capacity to bind Cu²⁺. However, it increased the binding capacity of Ca²⁺ and Zn²⁺ of the insoluble fiber fraction from rice and oat brans.     

Induced maturation and spawning: opportunities and applications for research on oogenesis

Broodstock management requires the ability to detect and regulate oocyte growth, acquisition of maturational competence, maturation of oocytes, and onset of ovarian atresia. Our research on temperate basses (genus Morone) has supported development of these capabilities. These investigations have revealed that accumulation of neutral lipid droplets and deposition of vitellogenin-derived yolk proteins in growing oocytes are independent processes with different sensitivities to changing day length and water temperature. In these fishes, completion of oocyte growth is marked by disappearance of vitellogenin from ovarian biopsy samples. Competence of females for induced spawning is predicted by the ability of biopsied follicles to initiate oocyte meiosis in vitro in response to insulin-like growth factor I. Cytoplasmic maturation of the oocytes is triggered by the maturation-inducing steroid hormone and can be monitored by evaluating degradation of the yolk proteins. Onset of ovarian atresia is indicated by the appearance of edema in the granulosa cell layer of biopsied follicles, and can be delayed for months by holding gravid females at abnormally low temperature (`cold banking'). These novel findings hold strong promise for application to other farmed fishes.