Evidence for a cholecystokinin gut-brain axis with modulation by bombesin

The relationship between cerebrospinal fluid and plasma cholecystokinin (CCK) levels was investigated by simultaneous withdrawal of CSF and blood from anesthetized mongrel dogs and measurement of CCK immunoreactivity by radioimmunoassay. A significant correlation occurred between CSF and plasma levels of CCK. During a CCK IV infusion, a statistically significant inverse correlation was noted between CSF and plasma values, while no significant relationship was noted during a bombesin (BBS) IV infusion. When infusion data were analyzed together with the appropriate baseline data, polynomial analysis revealed significant biphasic relationships for both CCK and BBS infusion studies. Intraventricular infusion of CCK did not alter plasma levels. These data suggest the existence of a mechanism relating CSF to plasma CCK levels (a gut to brain axis) with possible modulation or suppression by BBS.     

Purification of rat liver monoamine oxidase by octyl glucoside extraction and reconstitution

Catalytically active isoenzymes of rat liver monoamine oxidase have been copurified from the outer mitochondrial membrane by a novel method involving repetitive solubilization with octyl-β-d-glucopyranoside followed by reconstitution into lipid vesicles. As analyzed using sodium dodecyl sulfate-gel electrophoresis, the purified enzyme migrates as a single band of protein of molecular weight 60,000. The preparation is capable of metabolizing 576 nmol serotonin and 777 nmol β-phenylethylamine/min/mg protein. Apparent K_m values and sensitivity to the inhibitor clorgyline are very similar for the purified and outer mitochondrial membrane-bound enzyme when determined with the substrates β-phenylethylamine, serotonin, and tyramine.     

Expression of the human papillomavirus E7 oncogene during cell transformation is sufficient to induce susceptibility to lysis by activated macrophages.

Human papillomaviruses (HPV), and in particular HPV type 16, are etiologic agents in the development of cervical cancer, which is the second most common form of cancer in women worldwide. Mammalian cells are susceptible to transformation in vitro by the E6 and E7 oncogenes derived from the HPV-16 genome. NIH-3T3 cells transfected with the HPV-16 E7 oncogene were found to exhibit cytolytic susceptibility to murine-activated macrophages. In comparison, E6 oncogene-expressing cells were not susceptible to lysis by activated macrophages. The E7 oncoprotein is multifunctional, being capable of complexing with the retinoblastoma tumor suppressor gene (anti-oncogene) product, stimulating DNA synthesis, and causing cell transformation in vitro. Macrophage killing assays performed on cell lines expressing E7 mutants revealed that the ability to complex the retinoblastoma tumor suppressor gene product and stimulate DNA synthesis did not induce susceptibility to activated macrophages, whereas the ability of E7 to cause transformation was required to induce susceptibility to activated macrophages. These data suggest that cell transformation is a more important prerequisite for inducing susceptibility to activated macrophages than is the loss of tumor suppressor gene function. This study also provides an initial link between HPV-16 oncogene expression and the ability of activated macrophages to selectively recognize and destroy HPV-16-associated neoplastic cells.     

Bacterial species dominance within a binary culture biofilm.

Studies with two species of bacteria, Pseudomonas putida and Hyphomicrobium sp. strain ZV620, were carried out to evaluate the overall net rate of accumulation of biofilm, the biofilm species composition, and individual species shear-related removal rates. Bacterial cells of either or both species were deposited onto glass or biofilm surfaces to initiate multispecies biofilms. Subsequent biofilm development was carried out under known conditions of nutrient concentration and laminar flow. Establishment of a depositing organism in a biofilm composed of another species was found to be a function of the relative growth rates of the bacterial species. In the case of simultaneous species deposition and subsequent binary culture development, the faster-growing organisms rapidly became the dominant biofilm species, but the slower-growing organisms remained established within the biofilm and continued to increase in numbers over time. The results also indicated that the rate of cell removal by fluid shear for a species was a function of biofilm cell number only if the species concentration was uniform with depth; in essence, only the upper layers of the biofilm were sheared off.     

The Development of Pre- and Postsynaptic Components of the Noradrenergic System in the Rat Cerebellum

Abstract: Evidence based on the ability to accumulate [³H]noradrenaline by a mechanism sensitive to desmethylimipramine suggests that there is a period of hyperinnervation of the cerebellum by noradrenergic fibres around the beginning of the second postnatal week. Different developmental profiles for specific noradrenaline uptake and noradrenaline content indicate that invasion of the tissue by noradrenergic fibres precedes their full acquisition of transmitter. Developmental increases in the density of β-receptors and adenyl cyclase responsiveness to isoproterenol lags behind those of the presynaptic components and does not begin until the hyperinnervation is declining around day 12.     

The effects of cross-fostering on the behaviour of two species of North American lemmings, Dicrostonyx groenlandicus and Lemmus trimucronatus: I. Olfactory preferences

To determine the role of the maternal environment in the development of adult olfactory preferences, the young of two species of North American lemmings (Dicrostonyx groenlandicus and Lemmus trimucronatus) were reciprocally cross-fostered shortly after birth. In-fostered (reared by foster conspecific females) and non-fostered animals served as controls. When adult, subjects were tested for olfactory preferences in a free-choice Y-maze olfactometer. When compared to controls, cross-fostered animals showed increased preference for heterospecific odour. This effect was stronger for males than for females. These results suggest that adult species-specific odour preferences are learned during the neonatal period.     

The primary structure of a major polypeptide component from the venom of Naja melanoleuca.

The venom of the forest cobra, Naja melanoleuca, contains a number of homologous polypeptides containing between 60 and 71 amino acid resides. The primary structure of a major component (approx. 10% by weight of the crude venom) has been determined unambiguously. The molecule contians 61 amino acid residues and four disulphide bridges. It has not effect on neuromuscular transmission or the excitatory or inhibitory responses to acetylcholine of molluscan neurons. The molecule is similar to, but not identical with, the so-called cytotoxins VII2 and VII3 isolated, by others, from the same venom but reported to be minor components.     

The behavioral and somatic effects of ovariectomy and replacement therapy in female collared lemmings (Dicrostonyx groenlandicus)

Reproductive behavior and organ weights in intact estrous and diestrous, and in ovariectomized treated and untreated female collared lemmings (Dicrostonyx groenlandicus) were examined. Sexual behavior of intact diestrous and untreated ovariectomized females was similar, and females in both groups behaved differently from intact estrous females in scores for lordosis and mounting the male. Receptivity was observed in some females within 3 days after the first daily dose of as little as 0.1 μg of estradiol benzoate (EB) and in 83% of all females treated with 0.1 μg or more of EB for 5 days. Vaginal perforation and cornification were related to the dose of EB and length of treatment. The doses of EB used were not related to the lordosis quotient. Ovariectomy and subsequent EB treatment influenced uterine but not preputial gland weight. Adrenal weight was not influenced by ovariectomy or EB treatment, but the increased adrenal weights observed may have been related to the daily pairing of females with males.