Seabird diving behaviour reveals the functional significance of shelf-sea fronts as foraging hotspots

Oceanic fronts are key habitats for a diverse range of marine predators, yet how they influence fine-scale foraging behaviour is poorly understood. Here, we investigated the dive behaviour of northern gannets Morus bassanus in relation to shelf-sea fronts. We GPS (global positioning system) tracked 53 breeding birds and examined the relationship between 1901 foraging dives (from time-depth recorders) and thermal fronts (identified via Earth Observation composite front mapping) in the Celtic Sea, Northeast Atlantic. We (i) used a habitat-use availability analysis to determine whether gannets preferentially dived at fronts, and (ii) compared dive characteristics in relation to fronts to investigate the functional significance of these oceanographic features. We found that relationships between gannet dive probabilities and fronts varied by frontal metric and sex. While both sexes were more likely to dive in the presence of seasonally persistent fronts, links to more ephemeral features were less clear. Here, males were positively correlated with distance to front and cross-front gradient strength, with the reverse for females. Both sexes performed two dive strategies: shallow V-shaped plunge dives with little or no active swim phase (92% of dives) and deeper U-shaped dives with an active pursuit phase of at least 3 s (8% of dives). When foraging around fronts, gannets were half as likely to engage in U-shaped dives compared with V-shaped dives, independent of sex. Moreover, V-shaped dive durations were significantly shortened around fronts. These behavioural responses support the assertion that fronts are important foraging habitats for marine predators, and suggest a possible mechanistic link between the two in terms of dive behaviour. This research also emphasizes the importance of cross-disciplinary research when attempting to understand marine ecosystems.

Determination of risperidone and enantiomers of 9-hydroxyrisperidone in plasma by LC-MS/MS

A robust and validated liquid-liquid extraction LC-MS/MS method was developed for population pharmacokinetic analysis and therapeutic drug monitoring of risperidone and the enantiomers of its major active metabolite (+)-and (-)9-hydroxyrisperidone in pediatric patients. The method was rapid, sensitive and used a low sample amount (200 microL), which is very desirable for the pediatric population. The assay was validated from 0.2 to 50 ng/mL in plasma for all analytes. LLOQ for all analytes was 0.2 ng/mL. The extracts were analyzed by normal phase LC-MS/MS. The sample run time was 8 min. Intra- and interday precision for all analytes was < or =6%; method accuracy was between 89 and 99%. Additional experiments were performed to analyze matrix effects and identify a proper internal standard for each analyte. The validated method was used to study risperidone and its enantiomer metabolites in plasma as part of a population pharmacokinetic study in pediatric patients with pervasive developmental disorder (PDD).

Comparison of the effects of in vitro and in situ storage on the viability of mouse ovarian tissue collected after death

Ovarian tissues, collected or salvaged from endangered species at the time of gonadectomy or following their death, are being transported to genebanks for storage with the assumption that they will (subsequently) yield sufficient numbers of germ cells to help preserve the species. The present study aimed to quantify the impact of delays in collecting and/or processing ovarian tissue on the number of follicles in this tissue that remained normal after grafting. The study compared the viability of ovarian tissue stored in vitro (in phosphate-buffered saline) versus in situ (in the body) either on ice or at room temperature for 0 (non-stored fresh grafts), 3, 6, 12, 24 or 48 h. The conditions of storage had significant effects on the total number of morphologically normal follicles, with significantly more follicles in grafts developing from in vitro-stored tissue than in situ-stored tissue. Storage temperature and duration of storage, but not the storage temperature alone, influenced follicle survival. Tissue that was grafted immediately after collection (0 h) was best, but normal follicles were recovered in grafts stored in vitro (on ice or at room temperature) or in situ (on ice only) for up to 48 h before grafting. The rate of follicle loss over time was very rapid, with approximately 50% fewer follicles in grafts derived from tissue stored for only 3 h compared with non-stored fresh grafts (0 h). The results show that viable ovarian tissue can be salvaged from animals up to 48 h after death; however, in order to best protect the follicle population, the ovaries should be removed from the animal's body as soon as possible.

Postnatal development of presynaptic receptors that modulate noradrenaline release in mice

The objective of the study was to clarify the postnatal development of the following transmitter release-modulating receptors of noradrenergic neurons in mice: alpha2-adrenoceptors, muscarinic, opioid and cannabinoid receptors (inhibitory), beta-adrenoceptors and receptors for angiotensin II and bradykinin (facilitatory). Wildtype (NMRI) and in some cases alpha2A/D-adrenoceptor-deficient mice aged 1 day (P1) or 8-16 weeks (adults) were used. Hippocampal and occipito-parietal cortex slices and sympathetically innervated tissues (atria and vas deferens) were preincubated with [3H]-noradrenaline and then superfused and stimulated electrically. Stimulation led to distinct increases in tritium efflux which were abolished by tetrodotoxin or removal of calcium. Concentration-response curves of appropriate agonists and in the case of alpha2-autoreceptors antagonists were determined. For beta-adrenoceptors and angiotensin receptors, the interaction of agonists with antagonists was also examined. Results demonstrate that alpha2A/D-autoreceptors operate already at P1 whereas nonalpha2A/D-autoreceptors, presumably alpha2C, develop later. Of the various heteroreceptors, those of brain noradrenergic neurons (OP3 and ORL1) modulate the release of [3H]-noradrenaline at least as effectively at P1 as in adults. Those of peripheral sympathetic neurons (muscarinic, probably mainly M2, OP1, OP2, OP3, CB1, AT1 and B1), in contrast, operate less effectively or not at all at P1, with one exception: beta2-adrenoceptors increase the release of [3H]-noradrenaline (atria) to the same extent, irrespective of age. Overall, results indicate that brain and peripheral noradrenergic neurons release their transmitter already shortly after birth. Presynaptic receptor mechanisms mature differentially in the brain and the periphery. Moreover, the various presynaptic receptors differ in their postnatal development and may play differential roles at different ages.

Stimulation of mouse cultured sympathetic neurons by uracil but not adenine nucleotides

Cultured neurons from the paravertebral sympathetic chain of rats possess excitatory P2X as well as excitatory uracil nucleotide-sensitive P2Y receptors. Preliminary observations had indicated that the analogous neurons of mice lacked P2X receptors. This difference was now investigated. Thoracolumbar sympathetic neurons from one- to three-day-old mice were cultured for seven days. When the neurons were preincubated with [3H]noradrenaline and then superfused, ATP failed to cause any change in tritium outflow. UTP (3-300 microM) and UDP (30-100 microM), in contrast, caused marked increases, and so did nicotine (3-100 microM). The effect of UTP was not changed by suramin but abolished by tetrodotoxin and in the absence of calcium. The effect of nicotine was antagonized by hexamethonium and also abolished by tetrodotoxin and in the absence of calcium. Pre-exposure to UDP prevented the effect of UTP. In neurons studied by means of whole-cell patch-clamp techniques under current clamp, ATP lacked any effect. UTP (100 microM), UDP (100 microM) and nicotine (10 microM) caused depolarization accompanied by action potentials. Pre-exposure to UDP prevented the effect of UTP. In neurons studied under voltage clamp, ATP, UTP and UDP failed to cause any detectable current. Nicotine (10 microM), in contrast, elicited inward currents. Neither UTP nor UDP reduced the M-type potassium outward current. These results demonstrate a pronounced difference between cultured sympathetic neurons from the mouse and the rat paravertebral chain. Neurons from both species possess the nicotinic acetylcholine receptor. Neurons from both species also possess uracil nucleotide-sensitive P2Y receptors which, when activated, mediate depolarization, action potential firing and noradrenaline release; these effects are not due to inhibition of M-type potassium channels. Only the rat but not the mouse neurons, however, possess P2X receptors which, when activated, mediate cation entry, depolarization, action potential generation and transmitter release. The absence of functional P2X receptors makes the mouse neurons suitable for further study of the uracil nucleotide-sensitive P2Y receptors.

Temperature compensation of postsynaptic currents from the extraocular muscle of temperate teleost fishes

Miniature end plate currents were recorded from white inferior oblique extraocular muscle fibres of one temperate marine teleost (Aldrichetta forsteri, Family Mugilidae) and two temperate freshwater teleosts (Galaxias fasciatus, Family Galaxiidae and Oncorhynchus mykiss, Family Salmonidae). Miniature end plate currents were digitised and averaged over a temperature range of 5-25 degrees C. For each species, decay of miniature end plate currents was exponential and exhibited a strong temperature dependence. Lower temperatures resulted in prolonged decay phases, which decreased exponentially as a function of absolute temperature. Although values of the exponential time constant tau (tau) obtained for each species at 5 degrees C, 15 degrees C and 25 degrees C were significantly different, at any given temperature, there were no significant differences between tau values for the three species, despite differences in phylogeny (different families) and habitat (marine versus freshwater). At their normal temperature of 15 degrees C, mean values of tau for the three species ranged from 840 micros to 940 micros, and apparent activation energies ranged from -41 kJ mol(-1) deg(-1) to 50 kJ mol(-1) deg(-1). These observations confirm earlier reports that teleost miniature end plate currents are consistently shorter than those of other vertebrates.

Cryopreservation of mouse ovarian tissue following prolonged exposure to an Ischemic environment

In cases in which ovarian tissue is to be cryopreserved for tissue or gene banking it is important to maintain its integrity and viability. This study examined how delays between the death of an animal and the collection/cryopreservation of its ovarian tissue influenced follicle viability. Mouse ovaries were placed in PBS+antibiotic (in vitro) or left within the body (in situ) at room temperature for 0, 3, 6, 12, or 24 h following the death of the donor. These ovaries were cryopreserved at 1 degrees C/min on dry ice or in a -84 degrees C freezer using a passive cooling device or by conventional slow cooling (0.3 degrees C/min). The ovaries were grafted under the kidney capsule of ovariectomized recipient mice and collected 2 weeks later, and the size and number of follicles were determined. Cryopreserved ovarian tissue grafted immediately after the death of the donor contained numerous viable and healthy follicles independent of the cooling procedure (dry ice, 134 +/- 32; -84 degrees C, 165 +/- 54; slow, 214 +/- 55 follicles per half ovary). Tissues stored in vitro before cryopreservation retained viable follicles up to 12 h after death (dry ice, 30 +/- 15; -84 degrees C, 86 +/- 45; slow, 93 +/- 33), whereas tissue left in situ had significantly reduced follicle numbers within 3 h of death (dry ice, 36 +/- 12; -84 degrees C, 19 +/- 6; slow, 28 +/- 7). No significant difference was found between the cooling rates tested, indicating that a passive cooling container which cools at 1 degrees C/min is a suitable alternative to conventional slow cooling. We conclude that ovarian tissues for cryobanking should be cryopreserved as soon as possible after collection or death of the animal to ensure maximal follicular survival.

Follicular development in cryopreserved Common Wombat ovarian tissue xenografted to Nude rats

The Northern Hairy-nosed Wombat (Lasiorhinus krefftii) is a highly endangered marsupial species and every possible option for sustaining the species needs to be explored. One important approach may be the development of assisted reproductive technologies in the non-endangered Common Wombat (Vombatus ursinus) and Southern Hairy-nosed Wombat (Lasiorhinus latifrons) for application in breeding the Northern Hairy-nosed Wombat. In this study, it was examined whether cryopreserved Wombat ovarian tissue would develop following xenografting to immunologically deficient rats. Ovarian tissue was collected from Common Wombats (n = 3) and cryopreserved as small cortical pieces. After thawing the cortical pieces were grafted underneath the kidney capsule of Nude rats (n = 16). The grafts were recovered at 2, 4, and 10 weeks after transplantation and their gross and histological appearance investigated. Two weeks after grafting (n = 2), the tissue was revascularized and healthy primordial follicles were present. At week 4 (n = 2), some follicular development was present. At week 10, six rats received human chorionic gonadotrophin (hCG) to trigger follicle and oocyte maturation while another six rats were not given any treatment. The administration of hCG did not induce preovulatory follicles and oocyte maturation although type 5 follicles were present in ovarian tissue collected 10 weeks posttransplantation in both treated and untreated groups. This study demonstrates for the first time that Wombat ovarian tissue can survive and function when grafted into immunocompromized rats and that Wombat ovarian follicles can be recruited to growth and development in an ovarian xenograft. This model system has the potential to produce mature oocytes from endangered species for use in assisted reproductive technologies such as in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), and mature oocytes from non-endangered species for nuclear transfer which may be necessary for the preservation of critically endangered species.

Electrically evoked release of [(3)H]noradrenaline from mouse cultured sympathetic neurons: release-modulating heteroreceptors

Cultured neurons from the thoracolumbar sympathetic chain of newborn mice are known to possess release-inhibiting alpha(2)-autoreceptors. The present study was carried out in a search for release-modulating heteroreceptors on these neurons. Primary cultures were preincubated with [(3)H]noradrenaline and then superfused and stimulated by single pulses, trains of 8 pulses at 100 Hz, or trains of 36 pulses at 3 Hz. The cholinergic agonist carbachol reduced the evoked overflow of tritium. Experiments with antagonists indicated that the inhibition was mediated by M(2) muscarinic receptors. The cannabinoid agonist WIN 55,212-2 reduced the evoked overflow of tritium through CB(1) receptors. Prostaglandin E(2), sulprostone, and somatostatin also caused presynaptic inhibition. The inhibitory effects of carbachol, WIN 55,212-2, prostaglandin E(2), and somatostatin were abolished (at the highest concentration of WIN 55, 212-2 almost abolished) by pretreatment of the cultures with pertussis toxin (250 ng/ml). Several drugs, including the beta(2)-adrenoceptor agonist salbutamol, opioid receptor agonists, neuropeptide Y, angiotensin II, and bradykinin, failed to change the evoked overflow of tritium. These results demonstrate a distinct pattern of presynaptic inhibitory heteroreceptors, all coupled to pertussis toxin-sensitive G proteins. The lack of operation of several presynaptic receptors known to exist in adult mice in situ may be due to the age of the (newborn) donor animals or to the culture conditions.

Gonadotrophin administration can benefit ovarian tissue grafted to the body wall: implications for human ovarian grafting

Ovarian grafting provides a strategy for clinical infertility treatment and is starting to be used in conjunction with ovarian tissue storage for patients at risk of early ovarian failure. As patients are starting to return for their frozen stored tissue we need to ascertain how to maximise follicle survival when this tissue is grafted back to the patient. For research purposes ovarian tissue is commonly grafted to the kidney capsule as the rich capillary bed at this site favours rapid graft revascularization. This is however not an ideal site for natural conceptions or for the harvest of mature oocytes for in vitro fertilization. While oocytes would be relatively easy to recover from grafts on the abdominal wall or subcutaneous tissue graft revascularization at these sites is slower and evidence indicates that fewer follicles survive. As gonadotropins can upregulate angiogenic growth factors in the ovary this study was designed to test whether the administration of exogenous gonadotropins would increase the number of surviving follicles in grafts placed at less vascularised sites. We showed that exogenous gonadotrophins, given to either the donor or the recipient, could increase the number of developing follicles but the magnitude of this effect was influenced by the timing of the injections relative to the time of grafting.

Modulation of (3)H-noradrenaline release by presynaptic opioid, cannabinoid and bradykinin receptors and beta-adrenoceptors in mouse tissues

Release-modulating opioid and cannabinoid (CB) receptors, beta-adrenoceptors and bradykinin receptors at noradrenergic axons were studied in mouse tissues (occipito-parietal cortex, heart atria, vas deferens and spleen) preincubated with (3)H-noradrenaline. Experiments using the OP(1) receptor-selective agonists DPDPE and DSLET, the OP(2)-selective agonists U50488H and U69593, the OP(3)-selective agonist DAMGO, the ORL(1) receptor-selective agonist nociceptin, and a number of selective antagonists showed that the noradrenergic axons innervating the occipito-parietal cortex possess release-inhibiting OP(3) and ORL(1) receptors, those innervating atria OP(1), ORL(1) and possibly OP(3) receptors, and those innervating the vas deferens all four opioid receptor types. Experiments using the non-selective CB agonists WIN 55,212-2 and CP 55,940 and the CB(1)-selective antagonist SR 141716A indicated that the noradrenergic axons of the vas deferens possess release-inhibiting CB(1) receptors. Presynaptic CB receptors were not found in the occipito-parietal cortex, in atria or in the spleen. Experiments using the non-selective beta-adrenoceptor agonist isoprenaline and the beta(2)-selective agonist salbutamol, as well as subtype-selective antagonists, demonstrated the occurrence of release-enhancing beta(2)-adrenoceptors at the sympathetic axons of atria and the spleen, but demonstrated their absence in the occipito-parietal cortex and the vas deferens. Experiments with bradykinin and the B(2)-selective antagonist Hoe 140 showed the operation of release-enhancing B(2) receptors at the sympathetic axons of atria, the vas deferens and the spleen, but showed their absence in the occipito-parietal cortex. The experiments document a number of new presynaptic receptor locations. They confirm and extend the existence of marked tissue and species differences in presynaptic receptors at noradrenergic neurons.

Evaluation of the long-term function of cryopreserved ovarian grafts in the mouse, implications for human applications

Ovarian tissue storage has several potentially very valuable clinical applications, including the management of young female patients that are at risk of premature menopause. Ovarian tissue collection, used alone or in combination with oocyte and embryo cryopreservation, may help these patients safeguard their own future fertility. All available evidence from animal studies indicates that grafting of frozen ovarian tissue should be feasible in the human. This study on the mouse shows that frozen thawed ovarian tissue grafts can restore long term fertility to previously ovariectomised recipients. This, and other available evidence, indicates that ovarian tissue collection and storage, used alone or in combination with oocyte or embryo collection, may help safeguard the fertility of patients at risk of premature menopause.

Enhancement of noradrenaline release by angiotensin II and bradykinin in mouse atria: evidence for cross-talk between G(q/11) protein- and G(i/o) protein-coupled receptors

1. The interaction between alpha(2)-autoreceptors and receptors for angiotensin (AT(1)) and bradykinin (B(2)) was studied in mouse isolated atria. The preparations were labelled with [(3)H]-noradrenaline and then superfused with desipramine-containing medium and stimulated electrically. 2. Angiotensin II (10(-11) - 10(-7) M), angiotensin III (10(-10) - 10(-6) M) and bradykinin (10(-11) - 10(-7) M) enhanced the evoked overflow of tritium when preparations were stimulated with conditions that led to marked alpha(2)-autoinhibition (120 pulses at 3 Hz), but not when stimulated with conditions that led to little alpha(2)-autoinhibition (20 pulses at 50 Hz). 3. Blockade of alpha-adrenoceptors by phentolamine (1 or 10 microM) reduced or abolished the effect of angiotensin II and bradykinin on the overflow response to 120 pulses at 3 Hz. 4. Addition of the delta-opioid agonist [D-Ser(2)]-leucine enkephalin-Thr (DSLET, 0.1 microM), or of neuropeptide Y (0.1 microM), together with phentolamine, restored the effect of angiotensin II and bradykinin. 5. The beta-adrenoceptor agonist terbutaline (10(-9) - 10(-4) M) enhanced the evoked overflow of tritium irrespective of the degree of autoinhibition. 6. The experiments show that (i) a marked prejunctional facilitatory effect of angiotensin and bradykinin in mouse isolated atria requires prejunctional alpha(2)-autoinhibition; (ii) in the absence of alpha(2)-autoinhibition, activation of other prejunctional G(i/o) protein-coupled receptors, namely opioid and neuropeptide Y receptors, restores a marked effect of angiotensin II and bradykinin; and (iii) the facilitatory effect of terbutaline is not dependent upon the degree of alpha(2)-autoinhibition. The findings indicate that the major part of the release-enhancing effect elicited through prejunctional G(q/11) protein-coupled receptors is due to disruption of an ongoing, alpha(2)-autoreceptor-triggered G(i/o) protein mediated inhibition.

Noradrenaline release from cultured mouse postganglionic sympathetic neurons: autoreceptor-mediated modulation

The possible existence of alpha2-autoreceptors, P2-autoreceptors, and adenosine A1- or A2A-receptors was studied in cultured thoracolumbar postganglionic sympathetic neurons from mice. The cells were preincubated with [3H]noradrenaline and then superfused. The selective alpha2-adrenoceptor agonist UK 14,304 reduced the electrically evoked overflow of tritium. When the cultures were stimulated by trains of increasing pulse number, ranging from a single pulse to 72 pulses at 3 Hz, the concentration-inhibition curve of UK 14,304 was shifted progressively to the right and the maximal inhibition obtainable became progressively smaller. Six alpha-adrenoceptor antagonists shifted the concentration-inhibition curve of UK 14,304 in a parallel manner to the right. Neither ATP (3-300 microM), adenosine (0.01-100 microM), the selective A1-receptor agonist cyclopentyladenosine (1-1,000 nM), nor the selective A2A-receptor agonist CGS-21680 (1-10,000 nM) changed the basal or the electrically evoked overflow of tritium. It is concluded that the cultured neurons possess presynaptic, release-inhibiting alpha2-autoreceptors. As in intact tissues, the effectiveness of presynaptic alpha2-adrenergic inhibition depends on the "strength" of the releasing stimulus. The pK(D) values of the six antagonists against UK 14,304 indicate that the autoreceptors belong to the pharmacological alpha2D and hence the genetic alpha(2A/D) subtype of alpha2-adrenoceptor. Neither P2-autoreceptors nor receptors for adenosine, the degradation product of ATP, were detected.

Mouse postganglionic sympathetic neurons: primary culturing and noradrenaline release

Basic properties of noradrenaline release were studied in primary cultures of thoracolumbar postganglionic sympathetic neurons taken from 1-3-day-old NMRI mice. After 7 days in vitro, the cultures were preincubated with [3H]noradrenaline and then superfused and stimulated electrically. Conventional trains of pulses (for example, 36 pulses at 3 Hz) as well as single pulses and brief high-frequency trains (for example, four pulses at 100 Hz) elicited a well-measurable overflow of tritium, which was abolished by 0.3 microM tetrodotoxin or omission of Ca2+, but not changed by 1 microM rauwolscine. In trains of one, two, four, six, eight, or 10 pulses at 3 Hz, the evoked overflow of tritium remained constant from pulse to pulse at 1.3 mM Ca2+, but declined slightly at 2.5 mM Ca2+. Tetraethylammonium at 10 mM selectively increased the overflow elicited by small pulse numbers and especially by a single pulse. In trains of 10 pulses delivered at 0.3, 1, 3, 10, 30, or 100 Hz, the evoked overflow of tritium increased from 0.3 to 30 Hz and then declined at 100 Hz. This relationship was particularly pronounced at low Ca2+ concentrations (for example, 0.3 mM). Tetraethylammonium at 10 mM selectively increased the overflow elicited by low frequencies of stimulation. It is concluded that primary cultures of mouse postganglionic sympathetic neurons can be used to investigate release of [3H]noradrenaline. The release is well measurable, even upon a single electrical pulse. It agrees with release in intact sympathetically innervated tissues in a number of fundamental properties, including the pulse number and frequency dependence. The preparation may be of special interest in conjunction with genetic manipulations in the donor animals.

Prejunctional angiotensin receptors involved in the facilitation of noradrenaline release in mouse tissues

The effect of angiotensin II, angiotensin III, angiotensin IV and angiotensin-(1-7) on the electrically induced release of noradrenaline was studied in preparations of mouse atria, spleen, hippocampus, occipito-parietal cortex and hypothalamus preincubated with [3H]-noradrenaline. The prejunctional angiotensin receptor type was investigated using the non-selective receptor antagonist saralasin (AT1/AT2) and the AT1 and AT2 selective receptor antagonists losartan and PD 123319, respectively. In atrial and splenic preparations, angiotensin II (0.01 nM-0.1 microM) and angiotensin III (0.01 and 0.1 nM-1 microM) increased the stimulation-induced overflow of tritium in a concentration-dependent manner. Angiotensin IV, only at high concentrations (1 and 10 pM), enhanced tritium overflow in the atria, while angiotensin-(1-7) (0.1 nM-10 microM) was without effect in both preparations. In preparations of hippocampus, occipito-parietal cortex and hypothalamus, none of the angiotensin peptides altered the evoked overflow of tritium. In atrial and splenic preparations, saralasin (0.1 microM) and losartan (0.1 and 1 microM), but not PD 123319 (0.1 microM), shifted the concentration-response curves of angiotensin II and angiotensin III to the right. In conclusion, in mouse atria and spleen, angiotensin II and angiotensin III facilitate the action potential induced release of noradrenaline via a prejunctional AT1 receptor. Only high concentrations of angiotensin IV are effective in the atria and angiotensin-(1-7) is without effect in both preparations. In mouse brain areas, angiotensin II, angiotensin III, angiotensin IV and angiotensin-(1-7) do not modulate the release of noradrenaline.

Pharmacological characterization of endothelin receptor subtypes in the guinea-pig prostate gland

Experiments have been conducted to investigate the actions of endothelins on the guinea-pig prostate gland. Saturation experiments with [125I]-endothelin-1 (2-800 pM) in guinea-pig prostatic homogenates indicated the presence of high affinity binding sites with an equilibrium dissociation constant (KD) of 230+/-50 pM, a maximum number of binding sites (Bmax) of 52+/-16 fmol mg(-1) protein or 269+/-61 fmol g(-1) tissue and a Hill coefficient (nH) of 1.01+/-0.03 (n = 3). Competition experiments revealed that binding of [125I]-endothelin-1 (20 pM) was inhibited with the following order of potency: endothelin-1 >>BQ-788 (N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methyl-Leu-D-Trp[1-+ ++CO2CH3-D-Nle-ONa])> BQ-123 (cyclo-D-Asp-L-Pro-D-Val-Leu-D-Trp) > or = sarafotoxin S6c. At concentrations with negligible influence on smooth muscle tone, endothelin-1, endothelin-2 and sarafotoxin S6b (1 nM-0.1 microM) produced concentration-dependent potentiation of the contractions evoked by electrical field stimulation with trains of 20 pulses at 10 Hz every 50 s, 0.5 ms pulse width and a dial setting of 60 V. In contrast, the endothelin ET(B) receptor-preferring agonist endothelin-3 (1 nM- 1 microM) was much less potent, and the endothelin ET(B) receptor-selective agonists sarafotoxin S6c and BQ-3020 (Ac-[Ala11,15]-endothelin-1 (6-21)), up to 1 microM, were without effect. The endothelin ET(A) receptor antagonist BQ-123 (1 microM) markedly inhibited the potentiation induced by endothelin-1, endothelin-2 and sarafotoxin S6b while the endothelin ET(B) receptor antagonist BQ-788 (1 microM) was less effective. While our binding data indicates the presence of ET(A) and ET(B) binding sites in the guinea-pig prostate, the endothelin-induced facilitation of neurotransmission to the prostatic smooth muscle is mediated largely via activation of endothelin receptors of the ET(A) subtype.

They cannot sit properly or move around: seating and mobility during treatment for developmental dysplasia of the hip in children

Children diagnosed with Developmental Dysplasia of the Hip (0.2% of live births) are often treated by splintage to hold the head of the femur in the acetabulum during early joint development. Whilst clinically effective, this can create difficulties for the parents in handling the child and affects the mobility of the family, which subsequently creates emotional and social difficulty resulting from the disruption of the family routine. To identify these problems and their order of priority, a survey of 113 recently affected families was carried out in England and Northern Ireland. Parents identified mobility, emotional and social problems. Splintage size and shape was the fundamental problem from which the other difficulties arose. Solutions to the basic difficulties of transporting and seating a child in splintage would largely alleviate the feelings of frustration felt by the families and enable more normal activities of daily living.

Multiple prejunctional actions of angiotensin II on noradrenergic transmission in the caudal artery of the rat

1. Angiotensin II produced concentration-dependent enhancement of both stimulation-induced (S-I) efflux of [3H]-noradrenaline and stimulation-evoked vasoconstrictor responses in isolated preparations of rat caudal artery in which the noradrenergic transmitter stores had been labelled with [3H]-noradrenaline. The threshold concentrations of angiotensin II for enhancement of S-I efflux (between 0.03 and 0.1 microM) and of the stimulation-evoked vasoconstrictor responses (about 0.3 microM) were 10-1000 times higher than those that have been found for several other vascular preparations. 2. The AT1 angiotensin II receptor antagonist losartan (0.01 and 0.1 microM), reduced or abolished the enhancement of S-I efflux by 1 and 3 microM angiotensin II and the enhancement of vasoconstrictor responses by 1 microM angiotensin II. Surprisingly, the combination of 0.01 microM losartan and 0.1 microM angiotensin II enhanced S-I efflux to a much greater extent than did 0.1 microM angiotensin II alone. Moreover, the combination of 0.01 microM losartan and 0.1 microM angiotensin II enhanced stimulation-evoked vasoconstrictor responses, in contrast to the lack of effect of 0.1 microM angiotensin II alone. 3. In a concentration of 0.01 microM, the angiotensin II AT2 receptor antagonist PD 123319 did not affect the enhancement of either S-I efflux or vasoconstrictor responses by angiotensin II. However, in a higher concentration (0.1 microM), PD 123319 antagonized the enhancement of both the S-I efflux and vasoconstrictor responses by angiotensin II. 4. In concentrations of 0.01 and 0.1 microM, PD 123319 prevented the marked enhancement of both S-I efflux and stimulation-evoked vasoconstrictor responses produced by the combination of 0.1 microM angiotensin II and 0.01 microM losartan. 5. The potentiation by losartan (0.01 microM) of the facilitatory effect of 0.1 microM angiotensin II on S-I efflux and on stimulation-evoked vasoconstriction was still observed in the presence of either the cyclooxygenase inhibitor indomethacin (3 microM), or the nitric oxide synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME, 100 microM). 6. The findings confirm our previous suggestion that, in the rat caudal artery, angiotensin II receptors similar to the AT1B subtype subserve enhancement of transmitter noradrenaline release. 7. The synergistic prejunctional interaction of 0.01 microM losartan and 0.1 microM angiotensin II may be due to either the unmasking by losartan of a latent population of angiotensin II receptors also subserving facilitation of transmitter noradrenaline release, or alternatively, losartan may block an inhibitory action of angiotensin II on transmitter noradrenaline release which normally opposes its facilitatory effect.

Angiotensin II receptors involved in the enhancement of noradrenergic transmission in the caudal artery of the spontaneously hypertensive rat

1. The effects of the AT1 receptor antagonist losartan and the AT2 receptor antagonist PD 123319, on actions of angiotensin II in isolated caudal arteries of spontaneously hypertensive (SH) and age-matched normotensive (Wistar-Kyoto) rats were compared. 2. Angiotensin II (0.1-3 microM) produced concentration-dependent increases in perfusion pressure in artery preparations from both SH and Wistar-Kyoto (WKY) rats, the maximal increase in the SH rat being significantly greater than the increase in WKY rats. The increase in perfusion pressure in preparations from both strains of rats was prevented by losartan (0.1 microM) and unaffected by PD 123319 (0.1 microM), indicating that the vasoconstrictor action of angiotensin II is subserved by AT1 receptors. 3. Angiotensin II (0.1-3 microM) produced concentration-dependent enhancement of both stimulation-induced (S-I) efflux of [3H]-noradrenaline and stimulation-evoked vasoconstrictor responses in isolated preparations of caudal artery from both SH and WKY rats, in which the noradrenergic transmitter stores had been labelled with [3H]-noradrenaline. The maximum enhancement of S-I efflux produced by angiotensin II (1 microM) was significantly greater in artery preparations from WKY rats than in preparations from SH rats, whereas the maximum enhancement of stimulation-evoked vasoconstrictor responses was greater in preparations from SH rats than in those from WKY rats. 4. In artery preparations from both WKY and SH rats, the AT1 angiotensin II receptor antagonist, losartan (0.01 and 0.1 microM), reduced or abolished the enhancement of both S-I efflux and vasoconstrictor responses by 1 microM angiotensin II. 5. The combination of 0.01 microM losartan and 0.1 microM angiotensin II enhanced both the S-I efflux and stimulation-evoked vasoconstrictor response in caudal artery preparations from WKY rats, whereas 0.1 microM angiotensin alone was ineffective. The AT2 receptor antagonist PD 123319 (0.01 and 0.1 microM) prevented the enhancement of both S-I efflux and stimulation-evoked vasoconstrictor responses by the combination of angiotensin II and losartan. 6. In contrast to findings in WKY preparations and those previously obtained for arteries from another normotensive strain (Sprague-Dawley), in artery preparations from SH rats there was no synergistic interaction between losartan and angiotensin II. Rather, combinations of 0.1 microM angiotensin II and PD 123319 (both 0.01 and 0.1 microM) enhanced S-I [3H]-noradrenaline efflux, whereas 0.1 microM angiotensin II alone was without effect. Moreover, losartan (0.1 microM) prevented the enhancement of S-I efflux by the combination of angiotensin II and PD 123319. 7. The present findings indicate that in the caudal artery of WKY and SH rats, and as previously found in Sprague-Dawley preparations, angiotensin II receptors similar to the AT1B subtype subserve enhancement of transmitter noradrenaline release. 8. As previously suggested for Sprague-Dawley caudal artery preparations, the synergistic prejunctional interaction of losartan and 0.1 microM angiotensin II in caudal artery preparations from WKY rats may be due to either the unmasking by losartan of a latent population of angiotensin II receptors subserving facilitation of transmitter noradrenaline release, or blockade by losartan of an inhibitory action of angiotensin II on transmitter release. 9. The synergistic interaction of PD 123319 and 0.1 microM angiotensin II in caudal arteries of SH rats may also be explained by either of the mechanisms proposed for the normotensive strains, but the involvement of different receptor subtypes would need to be postulated for each of the proposed mechanisms.

Transplantation of cryopreserved fetal ovarian tissue to adult recipients in mice

Sixteen-day-old fetal mouse ovaries were slowly frozen in 1.5 mol dimethylsulfoxide ml-1 and subjected to one of two thawing procedures--fast thaw or slow thaw. Fresh and frozen-thawed fetal ovaries were transplanted orthotopically (to the bursal cavity) to either bilaterally or unilaterally ovariectomized adult female recipients. Fresh fetal ovaries were also transplanted heterotopically (under the kidney capsule) to intact, bilaterally or unilaterally ovariectomized adult females. Transplantation of fetal ovaries to bilaterally ovariectomized adult recipients resulted in restoration of cyclic activity within 20.5 +/- 4.7 (mean +/- SEM) days or 23.4 +/- 0.8 days in orthotopic and heterotopic groups, respectively. Developing follicles and corpora lutea were observed within 4 weeks after transplantation of fetal ovaries to heterotopic sites and within 6 weeks after transplantation to orthotopic sites. After orthotopic transplantation, 33% of the recipients became pregnant. Orthotopic or heterotopic transplantation to intact of unilaterally ovariectomized recipients resulted in quiescence of the fetal ovary. After cryopreservation, transplantation of fetal ovaries to bilaterally ovariectomized recipients resulted in restoration of cyclic activity within 19.3 +/- 2.1 days and 23.4 +/- 5.1 days after transplantation in slow thaw and fast thaw groups, respectively. Fertility was restored to 86% of fast thawed and 25% of slow thawed fetal ovary transplants to bilaterally ovariectomized adult recipients. No ovarian tissue was observed on the side of the fetal graft in unilaterally ovariectomized recipients that received frozen-thawed fetal ovaries. These results demonstrate that cryopreserved fetal ovarian tissue can be transplanted to adult recipients with subsequent restoration of fertility and that this process is dependent on the absence of the ovaries of the recipients.

Evidence for the involvement of different receptor subtypes in the pre- and postjunctional actions of angiotensin II at rat sympathetic neuroeffector sites

1. The effects of the nonpeptide angiotensin II receptor (AT) antagonists losartan and PD 123319 on actions of angiotensin II in the rat caudal artery and rat vas deferens preparations were investigated. 2. Angiotensin II (1.0 microM) increased perfusion pressure in isolated segments of the rat caudal artery. This increase in perfusion pressure was prevented by the AT1-antagonist, losartan (0.1 microM) but was not affected by the AT2-antagonist, PD 123319 (0.1 microM). 3. Angiotensin II (0.1-3.0 microM) produced a concentration-dependent enhancement of the stimulation-induced (S-I) efflux of [3H]-noradrenaline from isolated segments of rat caudal artery in which the noradrenergic transmitter stores had been labelled with [3H]-noradrenaline. The maximum enhancement of S-I efflux was approximately 60% with 1.0 microM angiotensin II. 4. Losartan (0.01 and 0.1 microM) reduced the enhancement of S-I efflux produced by 1.0 microM angiotensin II in the caudal artery. 5. PD 123319 (0.01 microM) did not affect the enhancement of S-I efflux produced by angiotensin II (1.0 microM) in the caudal artery. However, in a higher concentration (0.1 microM), PD 123319 reduced the enhancement of S-I efflux produced by 1.0 microM angiotensin II. 6. Angiotensin II produced concentration-dependent enhancement of the purinergic twitch responses (1 pulse/60 s) in the rat vas deferens. 7. Losartan (0.03 microM) and PD 123319 (0.03 microM) each reduced the angiotensin II-induced enhancement of the twitch responses in the rat vas deferens. 8. These findings indicate that the enhancement of sympathetic neuroeffector transmission in both the caudal artery and vas deferens of the rat involves angiotensin receptor subtype(s) sensitive to both losartan and PD 123319. In contrast, the direct vasoconstrictor effect of angiotensin II in the rat caudal artery involves activation of a receptor subtype sensitive only to losartan.

Human ornithine transcarbamylase. Purification and characterization of the enzyme from normal liver and the liver of a Reye's syndrome patient

Ornithine transcarbamylase was purified and characterized from normal human liver. The properties of this enzyme were compared to those of ornithine transcarbamylase purified from the liver of a patient with Reye's syndrome. The enzyme isolated from both sources appeared virtually identical for a variety of biochemical characteristics. The native molecular weight of ornithine transcarbamylase is 110,000 as determined by gel filtration. Electrophoresis of the enzyme, dissociated by sodium dodecyl sulfate, indicated that the enzyme exists as a trimer of identical or similar subunits of 36,500 daltons. Ornithine transcarbamylase from normal liver has an isoelectric point of 7.95, and the value for the enzyme from the Reye's syndrome liver was 8.05. No evidence of multiple species was found during the purification or subsequent characterization of the enzyme. The enzyme exhibited normal Michaelia-Menten kinetics, and the apparent Michaelis constants for L-ornithine and carbamyl phosphate are 0.20 mM and 0.09 mM, respectively. Inhibitor studies established the structural requirements for L-ornithine antagonists. L-Norvaline is the best competitive inhibitor of the enzyme with respect to L-ornithine. This study indicated that the reduced level of ornithine transcarbamylase activity commonly observed in Reye's syndrome is not necessarily due to structural or functional alterations of the enzyme.