Lysosomal and cytosolic ferritins A biochemical and electron-spectroscopic study

Summary Cytosolic and lysosomal ferritin and haemosiderin were isolated from rat livers which had been iron-loaded by four intraperitoneal injections of iron-dextran. The cytosolic and lysosomal ferritins, prepared in a phosphate-free medium, were subjected to gel-filtration chromatography on Sepharose 613, yielding four fractions: a cytosolic monomeric (CMF) and void-volume ferritin fraction (CVVF), and a lysosomal monomeric (LMF) and void-volume ferritin fraction (LVVF). Of each fraction the following aspects were examined: (a) immunoreactivity against specific antiserum; (b) the Fe/P mass ratio and the effect of dialysis on this ratio using electron probe micro-analysis (EPMA); (c) morphology and Fespecific imaging using electron spectroscopic imaging (ESI) and electron energy loss spectroscopy (EELS). For haemosiderin one aspect, the Fe/P ratio, was determined before and after extensive purification. The following results were obtained (a) All ferritin fractions reacted with anti- (rat liver ferritin). (b) The Fe/P ratios as determined in CMF in an haemosiderin were not affected by dialysis or extensive purification, respectively. The Fe/P ratio in CWF was affected by dialysis. In the lysosomal fractions, only a trace of phosphorus (LVVF) or no phosphorus (LMF) was detected. (c) Morphologically, CMF and CVVF were found to be rather homogeneous; the iron core diameters of both fractions were in the known size range. LMF and LVVF were of rather heterogeneous composition; the core diameters of these fractions were different. In conclusion: the phosphorus in ferritin and haemosiderin is firmly bound; Haemosiderin, when derived from ferritin, has to take up phosphorus in the lysosomes.     

The influence of blinding, olfactory bulbectomy and pinealectomy on plasma and anterior pituitary prolactin levels and on uterine and anterior pituitary weights in normal and neonatally androgenized rats

Lactating Sprague-Dawley rats had their litters adjusted to 8-10 pups on day 3 of lactation favoring females and some litters were injected with 1.25 mg of testosterone propionate to neonatally androgenize (NA) them. At 22-25 days of age both normal and NA animals were ovariectomized (OVX) and subjected to either sham olfactory bulbectomy (ANOS) + sham pinealectomy (PX), blinding (BLD) + ANOS or BLD + ANOS + pinealectomy (PX). At 13 weeks of age all animals were injected with 0.5 mg of polyestradiol phosphate. At 15 weeks of age the animals were fitted with atrial catheters and at 16 weeks of age blood samples (0.3 ml) were obtained every 3 hours over a 24 hour period. Uterine and anterior pituitary (AP) weights were recorded at sacrifice. Plasma and AP were assayed for prolactin (PRL) by RIA and AP were also assayed for PRL using the Nb2 lymphoma cell PRL bioassay. In both normal and NA animals, BLD + ANOS suppressed plasma PRL levels and PX partially prevented this response. Uterine weights were similar among groups while AP weights were significantly lower for sensory deprived animals. Anterior pituitaries extracted at pH 7.6 had a PRL concentration that was higher for the BLD + ANOS groups when estimated by either RIA or BA, a result that was not observed when the AP were extracted at pH 10.6. The amount of PRL extracted at pH 10.6 was twice that obtained at pH 7.6. Sensory deprived animals that were OVX prepubertally and administered estrogen as adults had a small but significant increase in mean plasma prolactin at 1700 hr. Both normal and NA animals responded in a similar manner to experimental manipulation.     

Metabolic and thermal physiology of pigeons and doves

Pigeons and doves (Columbidae) are an interesting group to examine for physiological adaptations to climate and diet because this cosmopolitan family comprises more than 300 species that are mostly granivores, although some are specialized frugivores. We determined allometric and phylogenetic effects on body temperature (T(b)), basal metabolic rate (BMR; J h(-1)), and wet thermal conductance (C(wet); J h(-1) C(-1)), and we examined mass (M) and phylogenetically corrected residuals for further effects of climate, diet, and landmass size (mainland or island). Independent contrasts, correlograms, autoregression, and phylogenetic eigenvector regression (PVR) were used to examine phylogenetically related effects. We found a small but significant phylogenetic pattern for body mass of columbids. For T(b), there was no significant effect of mass or phylogeny. There was a significant effect of climate on T(b) and no significant effects of diet or landmass without mass or phylogenetic correction, but after mass and phylogenetic correction, there were no effects of climate, diet, or landmass. For BMR, there was a strong allometric effect, and residuals were significantly lower for arid and tropical species but not for temperate species, compared to predictions for nonpasserine birds. There was a nearly significant autoregressive phylogenetic relationship for BMR parl0;r=0.44), and the strong allometry of BMR remained for independent contrasts (slope=0.731), autoregressive residuals (0.698), and PVR (0.705). Residuals, from regression of autoregression and PVR residuals of M and BMR, were significantly associated with climate: arid pigeons had a lower BMR residual than tropical and temperate pigeons. PVR residuals were significantly affected by landmass (island columbids had a smaller residual than mainland columbids), but autoregression residuals were not. There was no association of autoregression or PVR residuals with diet. For C(wet), there was a strong allometric effect, and residuals for columbids were significantly higher compared to other birds. There was no significant relationship for C(wet) of columbids to climate, diet, or landmass. There was no significant autoregressive or PVR relationship for C(wet), and the strong allometry remained after phylogenetic analysis by independent contrasts (slope=0.501), autoregression (0.509), and PVR (0.514). Residuals from autoregression and PVR were not significantly correlated with climate, diet, or landmass (mainland/island).     

Serum and Hair Nickel Levels and Breast Cancer: Systematic Review and Meta-Analysis

Several studies have investigated the relationship between serum and hair nickel (Ni) concentration and breast cancer, but the results were inconsistent. Thus, we conducted a systematic review and meta-analysis to evaluate the association between serum and hair nickel levels and breast cancer. Nine studies determining the serum nickel levels and six studies evaluating the hair nickel levels were identified in a systematic search of PubMed, China Knowledge Resource Integrated Database, Wanfang, and China Biomedical Literature Service System databases. Based on a random-effects model, standard mean differences (SMD) and the corresponding 95% confidence intervals (CI) were pooled to compare the nickel levels between different groups. Compared with healthy controls, the serum nickel levels in breast cancer were significantly higher (SMD (95% CI) 1.76 (0.82, 2.70)), as well as in those post-treated cases (SMD (95% CI) 2.56 (1.18, 3.94)). For breast cancer cases, the treatment made no significant decrease in serum nickel levels (SMD (95% CI) ?0.29 (?1.17, 0.59)). In hair, the nickel levels in breast cancer were slightly higher than in controls, but not significant (SMD (95% CI) 0.16 (?1.08, 1.40)). In conclusion, high serum nickel levels were associated with breast cancer, and nickel exposure might be a risk factor for breast cancer.     

Purification and properties of soluble and bound gamma-glutamyltransferases from radish cotyledon

Soluble and cell wall bound gamma-glutamyltransferases (GGTs) were purified from radish (Raphanus sativus L.) cotyledons. Soluble GGTs (GGT I and II) had the same M(r) of 63,000, and were composed of a heavy subunit (M(r), 42,000) and a light one (M(r), 21,000). The properties of GGT I and II were similar. Bound GGTs (GGT A and B) were purified to homogeneity from the pellet after the extraction of soluble GGTs. GGT A and B were monomeric proteins with an M(r) of 61,000. The properties of GGT A and B were similar. Thus, bound GGTs were distinguished from soluble GGTs. The optimal pHs of soluble and bound GGTs were about 7.5. Both soluble and bound GGTs utilized glutathione, gamma-L-glutamyl-p-nitroanilide, oxidized glutathione and the conjugate of glutathione with monobromobimane as substrates, and were inhibited by acivicin, but soluble GGTs were also distinguished from bound GGTs with regard to these properties.     

Metal and metal-ATP interactions with brain and cardiac adenylate cyclases.

Metal (Me) and MeATP interactions with adenylate cyclases associated with rabbit ventricular particles and with a detergent-dispersed preparation from rat cerebellum have been studied. data were simulated to fit kinetic models in which an inhibitor (HATP or ATP) is added in constant proportion to the variable substrate (MeATP). The specific models considered were that the enzyme binds (a) MeATP as the substrate; (b) MeATP as the substrate and HATP or ATP as an inhibitor; (c) MeATP as the substrate and free Me as an activator; and (d) MeATP as the substrate, free Me as an activator, and HATP or ATP as an inhibitor. Both equilibrium-ordered and random (rapid equilibrium assumption) types of sequential kinetic models were considered. The various models were tested using cardiac particulate adenylate cyclase in the presence of either a phosphoenolpyruvate-pyruvate kinase or a creatine phosphate-creatine kinase ATP-regeneration system. Although the enzyme with either system appeared to bind Mg2+ as an activator, one or both ATP-regeneration systems also seemed to interact directly with adenylate cyclase, making clear interpretations difficult. With the phosphoenolpyruvate-pyruvate kinase system, kinetic patterns on double reciprocal plots were linear as a function of MgATP, but with creatine phosphate-creatine kinase, kinetic patterns were concave downward. The kinetic models were further tested using the detergent-dispersed cerebellar enzyme, a preparation with low adenosine triphosphatase activity and not requiring the addition of an ATP-regeneration system. Reciprocal plots were linear and intersecting as a function of either MeATP or Me (Me = Mg2+ or Mn2+), and secondary replots of slopes and intersecting as function of either MeATP or Me (Me = Mg2+ or Mn2+), and secondary replots of slopes and intercepts also were linear. These data indicate that the brain detergent-dispersed enzyme conforms to a bireactant, sequential mechanism where free cation is a required activator and free ATP is not a potent inhibitor.     

Boron deficiency decreases growth and photosynthesis, and increases starch and hexoses in leaves of citrus seedlings

Seedlings of sweet orange (Citrus sinensis) were fertilized for 14 weeks with boron (B)-free or B-sufficient (2.5 or 10muM H(3)BO(3)) nutrient solution every other day. Boron deficiency resulted in an overall inhibition of plant growth, with a reduction in root, stem and leaf dry weight (DW). Boron-starved leaves showed decreased CO(2) assimilation and stomatal conductance, but increased intercellular CO(2) concentrations. Activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), NADP-glyceraldehyde-3-phosphate dehydrogenase (NADP-GAPDH) and stromal fructose-1,6-bisphosphatase (FBPase) were lower in B-deficient leaves than in controls. Contents of glucose, fructose and starch were increased in B-deficient leaves while sucrose was decreased. Boron-deficient leaves displayed higher or similar superoxide dismutase (SOD), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR) and glutathione reductase (GR) activities, while dehydroascorbate reductase (DHAR) and catalase (CAT) activities were lower. Expressed on a leaf area or protein basis, B-deficient leaves showed a higher ascorbate (AsA) concentration, but a similar AsA concentration on a DW basis. For reduced glutathione (GSH), we found a similar GSH concentration on a leaf area or protein basis and an even lower content on a DW basis. Superoxide anion (O(2)(-)) generation, malondialdehyde (MDA) concentration and electrolyte leakage were higher in B-deficient than in control leaves. In conclusion, CO(2) assimilation may be feedback-regulated by the excessive accumulation of starch and hexoses in B-deficient leaves via direct interference with chloroplast function and/or indirect repression of photosynthetic enzymes. Although B-deficient leaves remain high in activity of antioxidant enzymes, their antioxidant system as a whole does not provide sufficient protection from oxidative damage.     

Boar sperm velocity and motility patterns under capacitating and non-capacitating incubation conditions

This study compares the velocity and motility of boar sperm under capacitating and non-capacitating incubation conditions. Aliquots of pooled, washed boar sperm were incubated in either Tyrode's complete medium (TCM; a capacitating medium), Ca2+-free TCM (TCM-Ca2+), or Ca2+ and NaHCO3-free TCM (Tyrode's basal medium [TBM]; a non-capacitating medium). Motility patterns were determined every hour over a 3h period of incubation at 38 degrees C. Capacitation status was assessed by the chlortetracycline assay after 1 and 3h of incubation. Experiments were repeated five times. Compared to the TBM control, a significant increase was seen in the percentage of capacitated sperm after 1h of incubation in TCM: the kinematics of these sperm cells were favorably modified. However, the motility patterns of sperm cells incubated in TCM and TCM-Ca2+ were very similar. Under capacitating conditions (TCM), the coefficients of linearity (LIN) and straightness (STR) significantly increased over time (LIN values were significantly different after 3h of incubation, while STR values were significantly different after only 2 h). Significant correlations were seen between LIN and the percentage of cells showing the B pattern (r = 0.334, P < 0.05) and the number of acrosome reacted spermatozoa (r = 0.301, P < 0.05). This suggests that capacitated boar spermatozoa may have a species-specific motility pattern.     

In vitro embryo production and embryo transfer in domestic and non-domestic cats

Over a 5-year interval, multiple laparoscopic oocyte retrievals were done in fishing cats (Prionailurus viverrinus), caracals (Caracal caracal) and domestic cats after ovarian stimulation with gonadotropins. From 21 retrievals in five fishing cats, 579 preovulatory oocytes (mean = 27.6) were recovered and 348 embryos were produced in vitro (mean = 16.6). A total of 452 preovulatory oocytes (mean = 25.1) were recovered from 18 of 24 retrievals in six caracals and 297 (mean = 16.6) embryos were produced. An additional 16 caracal embryos (19%) were produced after in vitro maturation of 83 oocytes, 59 of which came from six retrievals producing only immature oocytes. The presence of corpora lutea at oocyte retrieval occurred in each species (1) at a similar frequency (33%) and (2) more frequently during January through May (11 of 15 retrievals) than during the latter half of the year (4 of 30 retrievals). Of the 12 embryo transfer procedures done in fishing cats, one pregnancy (8%) was obtained and one live kitten born after the auto-transfer of 10 Day-6 embryos. In caracals, a total of 46 Day-4 or Day-5 embryos were auto-transferred to six recipients, one of which delivered two live kittens. Then, 109 caracal embryos were cryopreserved before thawing and transferring to nine recipients (mean = 12.1) on Days 5 or 6. From three pregnancies established (33%), a total of three kittens were born. Two to six gonadotropin treatments/oocyte retrievals were done in domestic cats during 1999 through 2003; an average of 24.9, 23.5, 22.0, 23.1, 23.5 and 40.9 oocytes (P > 0.05) were recovered at the first through the sixth treatment cycles from 138, 138, 97, 49, 22, and seven retrievals, respectively.     

Distribution of prepubertal and adult goat oocyte cortical granules during meiotic maturation and fertilisation: ultrastructural and cytochemical study

The aim of this study was evaluate cortical granule (CG) distribution during in vitro maturation (IVM) and fertilisation of prepubertal goat oocytes compared to CG distribution of ovulated and in vitro fertilised oocytes from adult goats. Oocytes from prepubertal goats were recovered from a slaughterhouse and were matured in M199 with hormones and serum for 27 hr. Ovulated oocytes were collected from gonadotrophin treated Murciana goats. Frozen-thawed spermatozoa were selected by centrifugation in percoll gradient and were capacitated in DMH with 20% steer serum for 1 hr. Ovulated and IVM-oocytes were inseminated in DMH medium with steer serum and calcium lactate for 20 hr. Oocytes and presumptive zygotes were stained with FITC-LCA (Lens culinaris agglutinin labelled with fluorescein isothiocyanate) and observed under a confocal laser scanning microscope. Ultrastructure morphology of oocytes and presumptive zygotes were analysed by transmission electron microscopy (TEM). Prepubertal goat oocytes at germinal vesicle stage show a homogeneous CG distribution in the cytoplasm. IVM-oocytes at Metaphase II (MII) and ovulated oocytes presented CGs located in the cortex with the formation of a monolayer beneath to the plasma membrane. At 20 hr postinsemination (hpi), zygotes from IVM-oocytes showed a complete CG exocytosis whereas zygotes from ovulated oocytes presented aggregates of CGs located at the cortical region. Images by TEM detected that CGs were more electrodense and compacts in oocytes from prepubertal than from adult goats.     

High-light stress and photoprotection in Umbilicaria antarctica monitored by chlorophyll fluorescence imaging and changes in zeaxanthin and glutathione

The effect of high light on spatial distribution of chlorophyll (Chl) fluorescence parameters over a lichen thallus (Umbilicaria antarctica) was investigated by imaging of Chl fluorescence parameters before and after exposure to high light (1500 micro mol m (-2) s (-1), 30 min at 5 degrees C). False colour images of F (V)/F (M) and Phi (II) distribution, taken over thallus with 0.1 mm (2) resolution, showed that maximum F (V)/F (M) and Phi (II) values were located close to the thallus centre. Minimum values were typical for thallus margins. After exposure to high light, a differential response of F (V)/F (M) and Phi (II) was found. The marginal thallus part exhibited a loss of photosynthetic activity, manifested as a lack of Chl fluorescence signal, and close-to-centre parts showed a different extent of F (V)/F (M) and Phi (II) decrease. Subsequent recovery in the dark led to a gradual return of F (V)/F (M) and Phi (II) to their initial values. Fast (30 min) and slow (1 - 22 h) phase of recovery were distinguished, suggesting a sufficient capacity of photoprotective mechanisms in U. antarctica to cope with low-temperature photoinhibition. Glutathione and xanthophyll cycle pigments were analyzed by HPLC. High light led to an increase in oxidized glutathione (GSSG), and a conversion of violaxanthin to zeaxanthin, expressed as their de-epoxidation state (DEPS). The responses of GSSG and DEPS were reversible during subsequent recovery in the dark. GSSG and DEPS were highly correlated to non-photochemical quenching (NPQ), indicating involvement of these antioxidants in the resistance of U. antarctica to high-light stress. Heterogeneity of Chl fluorescence parameters over the thallus and differential response to high light are discussed in relation to thallus anatomy and intrathalline distribution of the symbiotic alga Trebouxia sp.     

Fever and behavioral thermoregulation in young and old rats

At standard laboratory ambient temperatures (T(a)) of 20-24 degrees C, peripheral injections of lipopolysaccharide (LPS) reliably produce fever in young rats. In contrast, old rats may show a blunted fever, no fever, or even hypothermia after LPS. In the present study we hypothesized that old rats might use behavioral thermoregulation to help them develop a fever. Young and old rats were implanted with temperature transmitters. At least 1 wk postoperatively they were placed in a thermally graded alleyway (T(a) 10-40 degrees C). On the third and sixth day they were taken out of the gradient, placed at an T(a) of 23 degrees C, injected intraperitoneally with LPS or saline, and left at 23 degrees C for 3 h. At the end of that time, all young rats had become febrile, whereas the old rats had not. When the rats were replaced in the thermal gradient, the young animals continued to develop a fever that was similar to fever in young rats left at 23 degrees C. The old animals chose significantly warmer positions in the thermal gradient than did the young animals and only then became febrile. Although there was a tendency for the young rats to prefer higher T(a) after LPS than after saline, these differences were not significant. However, the differences in the old rats were significant. These results suggest that the LPS had increased the thermal set point in the old rats, but they could develop febrile responses only at the warm T(a) they selected.     

Tetra- and hexahydro derivatives of aldosterone and 18-hydroxycorticosterone by chemical and microbial reductions

Preparative methods were developed for reduction with NaBH4 at 0 of 3 beta, 5 alpha- and 3 alpha, 5 beta-tetrahydroaldosterone (1) and (12) to their respective 20 alpha-ol derivatives 2a and 13a. Corroboration of structures was obtained by periodate oxidations to the lactols 3b and 14b and thence, by further oxidation, to the lactones 4 and 15 respectively; these lactones were also independently obtained from 1 and 12. Reduction with NaBH4 at 80 degrees C converted 1 and 12 into 18-hydroxy-3 beta, 5 alpha, 20- and 18-hydroxy-3 alpha, 5 beta, 20-hexahydrocorticosterone 6a and 17a respectively, which were mixtures of epimers at C-20. Compound 17a could also be prepared by reduction of the lactone 21 with sodium aluminum bis-(methoxyethoxy) hydride. Again, periodate oxidations of 6a and 17a gave the lactols 7b and 22b and thence, by Jones oxidation, the diketolactones 8 and 23, which were also prepared from 18-hydroxy-11-dehydrocorticosterone (10) and 18-hydroxycorticosterone (24) respectively. Improved conditions for reduction with Clostridium paraputrificum permitted convenient conversion of aldosterone (11), the corresponding 18 leads to 11 lactone 18a and 18-hydroxycorticosterone (24) into their 3 alpha, 5 beta-tetrahydro derivatives.     

SARS病毒N蛋白、E蛋白在大肠杆菌中的表达与鉴定

本研究通过RT-PCR反应获得了SARS冠状病毒核衣壳蛋白(N)和膜蛋白(E)基因,将n基因和e基因克 隆到大肠杆菌表达载体pGEX-KG上,并在大肠杆菌中以可溶形式获得高效表达,表达产物经亲和层析纯化。重 组蛋白N与SARS病毒抗体呈现特异性的反应,为进一步研究SARS病毒感染免疫应答机制和早期诊断奠定基础     

Diel and distributional abundance patterns of fish embryos and larvae in the lower Columbia and Deschutes rivers

Diel and distributional abundance patterns of free embryos and larvae of fishes in the lower Columbia River Basin were investigated. Ichthyoplankton samples were collected in 1993 during day and night in the main-channel and a backwater of the lower Columbia River, and in a tributary, the Deschutes River. Fish embryos and larvae collected in the main-channel Columbia River were primarily (85.6%) of native taxa (peamouth Mylocheilus caurinus, northern squawfish Ptychocheilus oregonensis, suckers Catostomus spp., and sculpins Cottus spp.), with two introduced species (American shad Alosa sapidissima and common carp Cyprinus carpio) comprising a smaller percentage of the catch (13.3%). Similarly, in the Deschutes River native taxa [lampreys (Petromyzontidae), minnows (Cyprinidae), and suckers Catostomus spp.] dominated collections (99.5% of the catch). In contrast, 83.5% of embryos and larvae in the Columbia River backwater were of introduced taxa [American shad, common carp, and sunfishes (Centrarchidae)]. In all locations, all dominant taxa except sculpins were collected in significantly greater proportions at night. Taxon-specific differences in proportions of embryos and larvae collected at night can in some instances be related to life history styles. In the main-channel Columbia River, northern squawfish and peamouth were strongly nocturnal and high proportions still had yolksacs, suggesting that they had recently hatched and were drifting downriver to rearing areas. In contrast, sculpin abundances were similar during day and night, and sculpins mostly had depleted yolksacs, indicating sculpins were feeding and rearing in offshore limnetic habitats. Taxon-specific diel abundance patterns and their causes must be considered when designing effective sampling programs for fish embryos and larvae.     

Differential effects of haloperidol and olanzapine on the expression of erythropoietin and its receptor in rat hippocampus and striatum

Compared with first-generation antipsychotics (FGAs), second-generation antipsychotics (SGAs) seem to be neuroprotective and trigger neuroplasticity. Because neuroplasticity is regulated by a variety of neurotrophic factors we studied differential effects of haloperidol (HAL, a FGA) and olanzapine (OLZ, a SGA) on temporal expression of erythropoietin (EPO), a potent neuroprotective factor and its receptor (EPOr) in rat brain. Rats (8-10/group) were treated with HAL or OLZ for 14 days (HAL-14 or OLZ-14) or 45 days (HAL-45 or OLZ-45). Animals were killed by decapitation or by perfusion to collect brains for immunoblotting and immunohistochemical analysis respectively. In hippocampus, the levels of both EPO and EPOr were significantly increased in HAL-14 (p < 0.001) and OLZ-14 (p < 0.001) groups. Their levels decreased in HAL-45 compared with levels in HAL-14 (EPO, p < 0.001; EPOr, p < 0.05), whereas the levels were further increased (EPO, p < 0.05) in OLZ-45 compared with OLZ-14. In striatum, the levels of both EPO and EPOr were unchanged in HAL-14 and EPO levels significantly decreased in HAL-45 (p < 0.05), whereas their levels were significantly increased in OLZ-14 and OLZ-45 compared with the vehicle-treated control (p < 0.001). Both EPO and EPOr were primarily expressed by neurons and endothelial cells. These data suggest that SGAs such as OLZ may have neuroprotective effects through expression of EPO that may be clinically relevant for long-term safe and beneficial management of psychotic patients.     

Paradoxical effects of oxytocin and vasopressin on basal prolactin secretion and the estrogen-induced prolactin surge

The roles of oxytocin (OT) and vasopressin (AVP) on both basal and estrogen-induced prolactin (PRL) secretion were examined. Adult female Sprague-Dawley rats that were ovariectomized for 3 weeks and received estrogen treatment for 1 week were used. Intravenous administration of hormones and serial blood sampling were accomplished through indwelling intraatrial catheters which were implanted two days before. Plasma PRL levels were measured by radioimmunoassay. Oxytocin at a dose of 20 micrograms/rat stimulated a moderate PRL release in the morning and lower doses (5 and 10 micrograms) were without effect. Vasopressin was most effective at a dose of 5 micrograms/rat in stimulating PRL release, while consecutive injections of higher doses (10 and 20 micrograms) were less effective. In contrast, TRH, ranging from 1 to 8 micrograms/rat, induced a dose-dependent increases in PRL secretion. Using the effective dosages determined from the morning studies, repeated injections of either OT, AVP or their specific antagonists MPOMeOVT [( 1-(beta-mercapto-beta, beta-cyclopentamethylene propanoic acid), 2-(O-methyl)tyrosine, 8-ornithine]-vasotocin) and d (CH2)5Tyr(Me)AVP ([1-(beta-mercapto-beta, beta-cyclo-pentamethylene propionic acid), 2-(O-methyl)tyrosine, 8-arginine]-vasopressin), were given hourly between 1300 to 1800 h and blood samples were obtained hourly from 1100 to 1900 h. It was found that either OT or AVP significantly reduced the afternoon PRL surge, while their antagonists were not as effective. When OT or AVP were administered together with their specific antagonists, the inhibitory effects of either hormone on PRL surge were reversed. Thus it is concluded that both OT and AVP assume a non-specific stress-like effect on PRL release, in which basal secretion is stimulated and surge secretion is inhibited.     

Chemical composition and biological activity of Nepeta parnassica oils and isolated nepetalactones

Essential oils of Nepeta parnassica, collected at different developmental stages, were analyzed by means of GC/MS. From the fifty-five identified constituents in samples A and B, representing 94.8% and 98.7% of the oils respectively, 4a(alpha),7alpha,7alpha(beta)-nepetalactone (22.0%), 1,8-cineole (21.1%), alpha-pinene (9.5%) and 4a(alpha),7,beta,7alpha(beta)-nepetalactone (7.9%) were the major components of sample A (vegetative stage), whereas in sample B (flowering stage) the main contributors were 1,8-cineole (34.6%), 4a(alpha),7alpha,7a(alpha)-nepetalactone (17.3%), alpha-pinene (11.4%) and 4a(alpha),7alpha,7alpha(beta)-nepetalactone (8.9%). The oils were tested on human health important insects such as the Pogonomyrmex sp. ants and the Culex pipiens molestus mosquitoes with promising results on insect repellency/toxicity.     

Preparation and some properties of giant liposomes and proteoliposomes

Optimal conditions for formation of giant liposomes and proteoliposomes were investigated. A suspension of small unilamellar vesicles made of various phospholipids in a buffer of 0-3 M KCl, 0.1 mM EDTA, and 20 mM MOPS (pH 7.0) was subjected to a freeze-thaw treatment. Giant multilamellar liposomes of diameter ranging from 10 to 60 microns were found to form from phospholipid mixtures containing phosphatidylethanolamine as a major component and phosphatidylserine as a minor component. The concentration of KCl optimal for the giant vesicle formation was 30-500 mM. By applying a patch-pipette to a giant liposome, suitable conditions for obtaining a high-resistance (giga-ohm) seal were sought. It was found that use of a patch-pipette of relatively small tip diameter (less than 1 micron), the presence of divalent metal cations in the suspension medium and inflation of vesicles in a hypotonic solution facilitated giga-seal formation. In a suspension of asolectin (soybean phospholipid) vesicles which had been subjected to the freeze-thaw treatment, giant unilamellar vesicles were found. They could be held on the tip of a suction pipette and impaled with a microelectrode filled with an EGTA solution. Small unilamellar proteoliposomes were prepared by the cholate-dialysis method from asolectin and sarcoplasmic reticulum vesicles, and were subjected to a freeze-thaw cycle. When the ratio of exogenous phospholipid to protein was larger than 10, giant multilamellar vesicles were formed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Diminished mesenteric vaso- and venoconstriction and elevated plasma ANP and BNP with simulated microgravity.

Diminished constriction of arteries and veins following exposure to microgravity or bed rest is associated with a reduced ability to augment peripheral vascular resistance (PVR) and stroke volume during orthostasis. We tested the hypothesis that small mesenteric arteries and veins, which are not exposed to large pressure shifts during simulated microgravity via head-down tail suspension (HDT), will exhibit decrements in adrenergic constriction after HDT in rats. Small mesenteric arteries and veins from control (Con; n = 41) and HDT (n = 35) male Sprague-Dawley rats were studied in vitro. Vasoactive responsiveness to norepinephrine (NE) in arteries (10(-9) to 10(-4) M) and veins (pressure-diameter responses from 2 to 12 cmH(2)O after incubation in 10(-6) or 10(-4) M NE) were evaluated. Plasma concentrations of atrial (ANP) and NH(2)-terminal prohormone brain (NT-proBNP) natriuretic peptides were also measured. In mesenteric arteries, sensitivity and maximal responsiveness to NE were reduced with HDT. In mesenteric veins there was a diminished venoconstriction to NE at any given pressure in HDT. Plasma concentrations of both ANP and NT-proBNP were increased with HDT, and maximal arterial and venous constrictor responses to NE after incubation with 10(-7) M ANP or brain natriuretic peptide (BNP) were diminished. These data demonstrate that, in a vascular bed not subjected to large hydrodynamic differences with HDT, both small arteries and veins have a reduced responsiveness to adrenergic stimulation. Elevated levels of circulating ANP or NT-proBNP could adversely affect the ability of these vascular beds to constrict in vivo and conceivably could alter the intrinsic constrictor properties of these vessels with long-term exposure.