Effect of substrate-free vascular perfusion upon cochlear potentials and glycogen of the stria vascularis

The effect of vascular perfusion of the anterior inferior cerebellar artery with synthetic blood containing no metabolic substrates upon the endolymphatic potential (EP) and the cochlear microphonics (CM) was determined in the guinea pig. In substrate-free perfusion the potentials were maintained for an average of 84 min. Subsequently, the EP declined at an average rate of 1.4 mV/min until a new steady-state level was temporarily established when the potential had dropped to about 30 mV. The decline of the CM appeared to be accounted for largely by the decline of the EP. During substrate-free perfusion prior to the onset of the decline of the potentials, the level of strial glycogen remained unchanged; glycogen decreased significantly only after the potentials had started to decline. When substrate-free vascular perfusion was accompanied by simultaneous substrate-free perilymphatic perfusion, the potentials started to decline immediately. On the basis of these data, we conclude that strial glycogen plays no role in the prolonged maintenance of the EP during substrate-free perfusion; rather, the potential seems to be maintained by entry of glucose (and presumably other substrates) from perilymph into the stria vascularis.     

EGF-induced redistribution of erbB2 on breast tumor cells: flow and image cytometric energy transfer measurements

The effects of the CCK(B) antagonists, CAM1028 and CI988 and a CCK(A) antagonist, CAM1481, were studied on the anxiety-related behaviour produced by withdrawal from chronic ethanol treatment, using the elevated plus maze. Cessation of chronic ethanol administration produced a profile, in both mice and rats, consistent with increase in anxiety-related behaviour. In mice, SC administration of CAM1028 or CI988 reduced the decrease in the time spent on the open arms, the number of entries into these arms and the increases in the latencies to first open arm entry, after withdrawal from the ethanol treatment. The increases in stretched attend postures and head dips from the closed arms and the central square seen during the withdrawal phase, were also decreased by the CCK(B) antagonists, but the decreases in the number of rears and in general activity were unaffected. The doses of CAM1028 and CI988 tested were 0.1 and 1 mg/kg; for some of the withdrawal-induced changes in behaviour only the 1 mg/kg dose was effective. In contrast, the CCK(A) antagonist, CAM1481, at the same doses, had little effect on the anxiety-related behaviour produced by withdrawal from chronic ethanol treatment, although it did decrease the changes in the number of rears and the head dipping behaviour. In rats, the majority of the changes produced by withdrawal from chronic ethanol treatment were decreased by CAM1028 at 1 mg/kg, although the decreases in open arm entries, rearing behaviour and in overall activity were unaffected. CAM1028, CI988 and CAM1481 had no effects on the behaviour of control mice or rats in the plus-maze. The results show that CCK(B) antagonists were effective in decreasing the majority of the anxiogenic effects of withdrawal from chronic ethanol treatment.     

Phenytoin penetration into brain after administration of phenytoin or fosphenytoin

Paraneoplastic pemphigus (PNP) is an autoimmune blistering disease that occurs in association with underlying neoplasms. PNP patients develop characteristic autoantibodies directed against multiple antigens, mostly identified as members of the plakin family of cytoplasmic proteins (desmoplakin I and II, bullous pemphigoid antigen I, envoplakin, and periplakin). HD1/plectin, another member of the plakin family, has not previously been detected in the characteristic PNP antigen complex, which may relate to practical difficulties associated with its large size (molecular weight approximately 500 kDa). In this study, a combination of immunoprecipitation and immunoblot is used to demonstrate that HD1/plectin is also recognized by sera from PNP patients. Thirteen of 16 PNP sera tested were positive for HD1/plectin compared with none of 43 control sera (11 pemphigus vulgaris, 11 pemphigus foliaceus, 11 bullous pemphigoid, and 10 normal individuals). Combined with our recent finding that desmoglein 3 and desmoglein 1 are cell surface target antigens in PNP, this demonstration of plectin/HD1 as another component of the antigen complex in PNP confirms that PNP is an autoimmune disease against desmoglein and plakin family molecules.     

Isolation, purification, and alteration of some functional groups of major milk proteins: a review

This review covers selected methods of isolation and purification of mainly alpha s-casein, beta-casein, kappa-casein, beta-lactoglobulin, and alpha-lactalbumin. Selected methods of alteration of some functional groups of these proteins also were reviewed. Isolation and purification of milk proteins per se are methods of modifying the individual milk proteins. Gram quantities of these proteins can now be purified in a relatively short time using ion-exchange resins. Due to the prominent use of non-food-grade reagents in the procedures for preparation of these milk proteins, individual proteins are not maximally utilized for the manufacture of food/feed and pharmaceutical products. Therefore, intensive research efforts are needed to obviate the problems associated with underutilization of milk proteins.     

Adrenomedullin, amylin, calcitonin gene-related peptide and their fragments are potent inhibitors of gastric acid secretion in rats

A release of radio-immunoassayable LHRH from the stalk-median eminence of neonatal piglets and prepubertal gilts was measured using an in vitro incubation system. The stalk-median eminence was collected from one-week-old male (n = 19) and female (n = 21) piglets and from 6-month-old prepubertal ovariectomized gilts given oestradiol benzoate (20 micrograms/kg b.w.; n = 52) or left untreated (control; n = 25) 30 or 68 h before slaughter. Each vial, containing the stalk-median eminence in 2 ml of Krebs-Ringer bicarbonate buffer, was incubated for 30 min, followed by 30 min incubations during which either basal release or the effect of adrenoreceptor antagonists and agonists on LHRH output was evaluated. There were no differences between the basal release of LHRH (x +/- SEM; pg/ml) from the stalk-median eminence of male (65.5 +/- 9.8) and female (66.3 +/- 9.6) newborn piglets. The addition of propranolol (10(-6) M) caused a 250% increase in LHRH release from the stalk-median eminence explants of neonatal males (p = 0.08) and females (p < 0.05). Neither norepinephrine nor phentolamine affected LHRH release from the stalk-median eminence of newborn males and females. The basal release of LHRH (pg/ml) from the stalk-median eminence explants collected from ovariectomized gilts given oestradiol benzoate 30 and 68 h before slaughter or left untreated was similar (147.5 +/- 36.1, 236.4 +/- 77.7 and 202.0 +/- 41.6, respectively). Propranolol evoked a significant increase in LHRH secretion from the stalk-median eminence in the control group, but not in the groups given oestradiol benzoate. Norepinephrine (10(-6) M) increased LHRH release from the stalk-median eminence collected from the control animals, 30 h and 68 h after oestradiol benzoate treatment by 48, 78 and 73 percent, respectively. Phentolamine (10(-6) M) did not affect LHRH release from the stalk-median eminence in control animals and ovariectomized gilts primed with oestradiol benzoate. Urapidil (10(-6) M, alpha 1-adrenoreceptor antagonist) did not affect the basal LHRH release from the stalk-median eminence of gilts from the control group and group slaughtered 30 h after oestradiol benzoate treatment, but caused a rapid increase of LHRH release from the stalk-median eminence 68 h after oestradiol benzoate treatment. Phenylephrine (10(-6) M) did not affect LHRH output from the stalk-median eminence collected at various time periods after oestradiol benzoate administration in vivo. These results suggest that in pigs, nerve terminals releasing LHRH at the stalk-median eminence level are sensitive to adrenergic stimulation or inhibition and that the adrenergic system can be modulated by estrogens in the prepubertal gilts.     

Divergent prolactin and pituitary-adrenal activity in rats selectively bred for different dopamine responsiveness

The present study explores the significance of brain dopamine phenotype for individual variation in the neuroendocrine stress response of the rat. For this purpose, we used two Wistar rat lines previously selected for high or low responsiveness of the dopamine system to apomorphine using the gnawing response as the selection criterion. Systemic administration of the drug evoked in apomorphine-susceptible (apo-sus) rats a vigorous gnawing response, whereas apomorphine-unsusceptible (apo-unsus) rats did not gnaw under these conditions. These two rat lines represent individuals displaying extreme differences in gnawing behavior that otherwise coexist in a normal Wistar population. In this study basal and stress-induced hypothalamic-pituitary-adrenal activity and PRL release were measured in chronically cannulated, freely moving rats that endured a conditioned emotional response. Tyrosine hydroxylase messenger RNA (mRNA), corticosteroid receptor mRNA, and in vivo retention of [3H]corticosterone were measured in rat brain sections using in situ hybridization and in vivo autoradiography. The result show that 1) apo-sus rats had a markedly reduced PRL response to stress compared to apo-unsus animals, whereas basal levels were not significantly different. A12 dopaminergic neurons in the arcuate nucleus expressed significantly higher levels of tyrosine hydroxylase mRNA in apo-sus rats, suggesting that the reduced stress-induced PRL release could be due to an increased inhibitory control by dopaminergic neurons; 2) in apo-sus rats, stress resulted in a sustained elevation of ACTH and free corticosterone levels, whereas the total corticosterone levels were not different between the two rat lines; 3) under basal morning conditions, apo-sus rats had significantly higher plasma ACTH, but, in contrast, lower free corticosterone than apo-unsus rats; total plasma corticosterone levels were not different; 4) the basal evening ACTH level was elevated in apo-sus rats; after removal of the adrenals in the morning, this increased ACTH level in apo-sus rats persisted into the afternoon 6 h postadrenalectomy; and 5) hippocampal mineralocorticoid (MR), but not glucocorticoid (GR), receptor capacity for the ligand comparable between the groups; the MR of apo-sus rats displayed an increased retention of [3H]corticosterone in all hippocampal cell fields measured 24 h adrenalectomy; MR and GR mRNA in hippocampus as well as GR mRNA in the paraventricular nucleus were not significantly different in the two rat lines. In conclusion, the data suggest a common genetic background for individual variation in stress responsiveness and dopamine phenotype. High dopamine reactivity is linked to a reduced PRL and an increased ACTH response after stress. These high dopamine responders display a hyporesponsive adrenal cortex and corticosteroid feedback resistance associated with altered brain corticosteroid receptor properties.     

Role of monensin PLGA polymer nanoparticles and liposomes as potentiator of ricin A immunotoxins in vitro

Monensin is a carboxylic ionophore which can potentiate the activity of ricin based immunotoxins (IT) in vitro and in vivo against a variety of human tumours. Monensin was encapsulated into nanoparticles (NP) by using biodegradable poly(DL-lactide-co-glycolide) (PLGA, 50:50). The NP were prepared by modified emulsification-solvent evaporation method. High shear homogenization followed by simultaneous stirring and bath sonication were used for preparing NP. The size of NP was determined by photon correlation spectroscopy using a BI 90 particle sizer (Brookhaven Instruments). The average size of NP could be decreased from 567 nm to 163 nm by increasing the concentration of polyvinyl alcohol from 10% to 100% of PLGA. The NP were spherical in shape as observed by Atomic Force Microscopy. The concentration of monensin in the NP was analyzed by HPLC and the entrapment efficiency was found to be more than 12%. The zeta potential of NP was -25.8 (+/- 1.3) mv, which did not change significantly after resuspension of the freeze dried sample. The NP were tested against HL-60 and HT-29 human tumour cell lines in vitro. Monensin NP potentiated the activity of IT by 40 to 50 times against these cell lines. There was however, no difference between the NP and liposomes for their potentiating affect of IT against the two tumour cell lines.     

A new animal model for molecular biological analysis of the implant-tissue interface: spatial expression of type XII collagen mRNA around a titanium oral implant

The objective of this study was to develop an animal model to investigate the molecular biological healing events at the tissue-implant surface occurring in the alveolar bone. Newly designed mini-titanium implants (2mm in length and 1 mm in diameter) were placed in the maxilla of retired-breeder male Sprague-Dawley rats. The implants were placed in freshly drilled holes in the maxillary bone, or in an area close to the roots of the maxillary first molar. The healing phase in each group was studied histologically at 28 days and at 56 days by means of non-decalcified polymethylmethacrylate-embedded sections and decalcified paraffin-embedded sections. Initial osseointegration was observed at 28 days, with mature osseointegration seen at 56 days. Specimens with implants placed immediately adjacent to the root showed fibrous healing at the implant-tissue surface. As a pilot study, the expression of type XII collagen, a molecular marker specific to the mature periodontal ligament (PDL), was studied by in situ hybridization. There was an absence of type XII expression close to the implant surface, whereas there was a zone of type XII collagen expression closest to the bony wall. Our preliminary results indicated a significant molecular variation in the fibrous-implant interface. This model will be useful in studies of the wound-healing patterns of the extracellular matrix around oral implants specifically relevant to alveolar bone osseointegration and potential formation of PDL.