Gonadotropin-releasing hormone-stimulated phosphoinositide hydrolysis in the anterior pituitary. Modulation by protein kinase C but not by cyclic nucleotides

Gonadotropin-releasing hormone (GnRH) produces a rapid and concentration-dependent hydrolysis of polyphosphoinositides in rat anterior pituitary cells in culture. Evaluation of the action of the decapeptide by measurement of [3H]-inositol phosphates and of prelabeled phosphoinositides demonstrated an effect on phosphatidylinositol-4,5-bis-phosphate and phosphatidylinositol-4-phosphate earlier than on phosphatidylinositol. The receptor antagonist [D-pGlu1,D-Phe2,D-Trp3,6]-luteinizing hormone-releasing hormone blocked the effect of GnRH on [3H]-inositol phosphate production. Protein kinase C activators attenuated GnRH-induced phosphoinositide hydrolysis, while neither cyclic AMP analogs nor cyclic GMP analogs were effective. These results indicate that phosphoinositide hydrolysis represents an important postreceptor transducing mechanism for GnRH action at the gonadotroph and that protein kinase C (but not cyclic nucleotides) may exert a negative feedback control on GnRH receptor-coupling mechanisms.     

Evaluation of a novel mouse model of intracisternal strychnine-induced trigeminal allodynia

Purpose

Intractable neuropathic dynamic allodynia remains one of the major symptoms of human trigeminal neuropathy and is commonly accepted to be the most excruciatingly painful condition known to humankind. At present, a validated animal model of this disorder is necessary for efficient and effective development of novel drug treatments. Intracisternal strychnine in rats has been shown to result in localized trigeminal dynamic allodynia, thus representing a possible model of trigeminal neuralgia. The purpose of this study was to validate a mouse model of trigeminal glycinergic inhibitory dysfunction using established positive (carbamazepine epoxide) and negative (morphine) controls.

Methods

The actions of conventional first-line treatment (carbamazepine epoxide [CBZe]) and clinically ineffective morphine were tested for trigeminal dynamic mechanical allodynia produced by intracisternal strychnine. In mice under halothane anesthesia, we injected either strychnine (0.3 μg), strychnine with CBZe (4 ng), or artificial cerebrospinal fluid (aCSF) intracisternally (i.c.). In a separate set of experiments, subcutaneous morphine (3 mg·kg^?1 sc) was injected with intracisternal strychnine. Dynamic mechanical allodynia was induced by stroking the fur with polyethylene (PE-10) tubing. The response of each mouse was rated to determine its allodynia score, and scores of each group were compared. In addition, in a separate dichotomous disequilibrium study, pairs of mice were injected with strychnine/saline, strychnine/strychnine-CBZe, or strychnine/strychnine-morphine. A blinded observer recorded which mouse of each pair had the greater global pain behaviour.

Results

Strychnine (i.c.) produced higher quantitative allodynia scores in the trigeminal distribution (mean 81.5%; 95% confidence interval [CI] 76.4 to 86.6) vs the aCSF group (mean 11.3%; 95% CI 8.1 to 14.4) (P < 0.0001). Carbamazepine epoxide (i.c.) completely abolished allodynia when co-injected with strychnine (mean 83.2%; 95% CI 78.1 to 88.4) vs strychnine alone (mean 3.2%; 95% CI ?0.9 to 7.2) (P < 0.0001). Morphine co-injected with strychnine did not result in reduced allodynia (mean 65.7%; 95% CI 42.0 to 89.4) compared with strychnine alone (mean 87.6%; 95% CI 77.6 to 97.6) (P = 0.16). In a further global allodynia assessment, strychnine (i.c.) produced greater allodynia than both aCSF and strychnine administered with CBZe (P = 0.03). Morphine (ip) administered with strychnine did not result in reduced global allodynia compared with strychnine administered alone (P = 1.0).

Conclusion

In this study, we have developed and validated a novel murine model of trigeminal dynamic allodynia induced by intracisternal strychnine. The use of mice to study trigeminal allodynia has many benefits, including access to a vast repository of transgenic mouse variants, ease of handling, low cost, and minimal variance of results. The present model may have utility in screening drug treatments for dynamic mechanical allodynia resulting from trigeminal neuropathies.     

Baculovirus Expression and Antigenic Characterization of Classical Swine Fever Virus E2 Proteins

Genes encoding a major structural glycoprotein, E2, of classical swine fever viruses (CSFV) Brescia (subgroup 1.2), Paderborn (subgroup 2.1) and Kanagawa (subgroup 3.4) were constructed by removing the transmembrane domain and adding a C‐terminal 6 histidine (His) tag. All the E2 constructs were efficiently expressed in a baculovirus system as 53‐kDa glycosylated proteins that were identified in Western blots by their reaction with anti‐His and CSFV‐specific antibodies. These proteins were used as ELISA antigens to confirm the existence of an antigenic relationship between the viruses using group‐specific polyclonal antisera. Antigenic differences were identified by Western blot and ELISA reactivity of the E2 proteins with a panel of monoclonal antibodies. Specifically, one monoclonal antibody (WH303) reacted with all three proteins, two monoclonal antibodies (M1660 and M1665) reacted with only the Brescia E2 protein, and three monoclonal antibodies (M1654, M1664 and M1669) reacted equally well with only Brescia and Kanagawa E2 proteins. Therefore, antibody reactivity profiles, established using recombinant E2 proteins, could be used to quickly identify novel CSFV strains as illustrated in this report with only a limited number of monoclonal antibodies. These proteins could also have added utility in the production of monoclonal antibodies and as critical reagents in diagnostic assays.     

Generalized training subset selection for statistical estimation of epicardial activation maps from intravenous catheter measurements

Catheter-based electrophysiological studies of the epicardium are limited to regions near the coronary vessels or require transthoracic access. We have developed a statistical approach by which to estimate high-resolution maps of epicardial activation from very low-resolution multi-electrode venous catheter measurements. This technique uses a linear estimation model that derives a relationship between venous catheter measurements and unmeasured epicardial sites from a set of previously recorded, high-resolution epicardial activation-time maps used as a training data set based on the spatial covariance of the measurement sites. We performed 14 dog experiments with various interventions to create an epicardial activation-time map database. This database included a total of 592 epicardial activation maps which were recorded using a sock array placed on the ventricles of dog hearts. We present five approaches, which examined sequential addition and removal of maps to select a generalized training set for the estimation technique. The selection consisted of choosing a subset of epicardial ectopic activation-time maps from the database of beats which resulted in estimation accuracy levels better than or at least similar to using all the maps in database. Our aim was to minimize the redundancy in the database and to be able to guide the eventual procedures required to obtain training data from open-chest surgery patients. The results from this study illustrated this redundancy and suggested that by including an optimal subset (around 100 maps) of the full database the estimation technique was able to perform as well as and even in some cases better than including all the maps in the database. The results also suggest that such an approach is feasible for providing accurate reconstruction of complete epicardial activation-time maps in a clinical setting and with fewer maps we can obtain similar reconstruction accuracy levels.     

Rural residents' perspectives on the rural ‘good death’: a scoping review

The ‘good death’ is one objective of palliative care, with many ‘good death’ viewpoints and research findings reflecting the urban voice. Rural areas are distinct and need special consideration. This scoping review identified and charted current research knowledge on the ‘good’ rural death through the perspectives of rural residents, including rural patients with a life‐limiting illness, to identify evidence and gaps in the literature for future studies. A comprehensive literature search of English language articles (no date filter applied) was conducted in 2016 (2 January to 14 February) using five library databases. Reference lists of included articles, recent issues of eight relevant journals and three grey literature databases were also hand‐searched. Twenty articles (for 17 studies and one systematic review) were identified after a two‐phase screening process by two reviewers, using pre‐determined inclusion criteria. Data from each study were extracted and charted, analysed using a thematic analysis of the included articles' content, and with a quantitative analysis of the scoping review. These papers revealed data collected from rural patients with a life‐limiting illness and family caregivers, rural healthcare providers, the wider rural community, rural community leaders and rural health administrators and policy makers. Rural locations were heterogeneous. Residents from developed and developing countries believe a ‘good death’ is one that is peaceful, free of pain and without suffering; however, this is subjective and priorities are based on personal, cultural, social and religious perspectives. Currently, there is insufficient data to generalise rural residents' perspectives and what it means for them to die well. Given the extreme importance of a ‘good death’, there is a need for further studies to elicit rural patient and family caregiver perspectives.     

Fluorescence in situ hybridization mapping of translocations and deletions involving the short arm of human chromosome 12 in malignant hematologic diseases

Translocations and deletions of the short arm of chromosome 12 [t(12p) and del(12p)] are common recurring abnormalities in a broad spectrum of hematologic malignant diseases. We studied 20 patients and one cell line whose cells contained 12p13 translocations and/or 12p deletions using fluorescence in situ hybridization (FISH) with phage, plasmid, and cosmid probes that we previously mapped and ordered on 12p12-13. FISH analysis showed that the 12p13 translocation breakpoints were clustered between two cosmids, D12S133 and D12S142, in 11 of 12 patients and in one cell line. FISH analysis of 11 patients with deletions demonstrated that the deletions were interstitial rather than terminal and that the distal part of 12p12, including the GDI-D4 gene and D12S54 marker, was deleted in all 11 patients. Moreover, FISH analysis showed that cells from 3 of these patients contained both a del(12p) and a 12p13 translocation and that the affected regions of these rearrangements appeared to overlap. We identified three yeast artificial chromosome (YAC) clones that span all the 12p13 translocation breakpoints mapped between D12S133 and D12S142. They have inserts of human DNA between 1.39 and 1.67 Mb. Because the region between D12S133 and D12S142 also represents the telomeric border of the smallest commonly deleted region of 12p, we also studied patients with a del(12p) using these YACs. The smallest YAC, 964c10, was deleted in 8 of 9 patients studied. In the other patient, the YAC labeled the del(12p) chromosome more weakly than the normal chromosome 12, suggesting that a part of the YAC was deleted. Thus, most 12p13 translocation breakpoints were clustered within the sequences contained in the 1.39 Mb YAC and this YAC appears to include the telomeric border of the smallest commonly deleted region. Whether the same gene is involved in both the translocations and deletions is presently unknown.     

Release of Pituitary Growth Hormone by Prostaglandins and Dibutyryl Adenosine Cyclic 3′:5′-Monophosphate in the Absence of Protein Synthesis

Effects of prostaglandins on the incorporation of [4,5-(3)H]leucine into growth hormone and its subsequent release into the incubation medium were studied. Incubation of rat anterior pituitary glands with 10(-6) M prostaglandin PGE(1) in tissue culture medium 199 for 7 hr caused a 40-300% increase in the release of labeled growth hormone into the incubation medium. PGE(1) at 10(-8) M increased growth hormone synthesis but not release. At 10(-6) M, PGE(2) had effects similar to PGE(1); PGA(1) increased growth hormone synthesis but not release. PGF(2alpha) was without effect on either synthesis or release of growth hormone.Prolactin synthesis and release were not affected by prostaglandins. All of the prostaglandins, at 10(-4) M, increased adenyl cyclase activity in the pituitary gland but phosphodiesterase activity was unaltered. Dibutyryl cyclic AMP, with or without caffeine, caused an up to 300% increase in labeled growth hormone release. No consistent effect of prolactin was observed. If potassium concentration was increased 10-fold, a 215% increase in growth hormone release was observed. A combination of hypertonic potassium and 10(-6) M PGE(1) increased growth hormone release 325%, suggesting that potassium and prostaglandins act by independent mechanisms. Addition of theophylline to pituitary gland, incubated in vitro, increased both the synthesis and release of growth hormone. Although fluoride greatly stimulated growth hormone release, it completely inhibited the incorporation of leucine into the hormone. Similarly, puromycin inhibited synthesis of growth hormone but did not block release induced by prostaglandin, dibutyryl cyclic AMP, theophylline, or fluoride. Prostaglandins increase pituitary adenyl cyclase activity and, presumably via cyclic AMP, increase growth hormone release, independently of protein synthesis.