Rating norms should be calculated from cumulative link mixed effects models

Studies which provide norms of Likert ratings typically report per-item summary statistics. Traditionally, these summary statistics comprise the mean and the standard deviation (SD) of the ratings, and the number of observations. Such summary statistics can preserve the rank order of items, but provide distorted estimates of the relative distances between items because of the ordinal nature of Likert ratings. Inter-item relations in such ordinal scales can be more appropriately modelled by cumulative link mixed effects models (CLMMs). In a series of simulations, and with a reanalysis of an existing rating norms dataset, we show that CLMMs can be used to more accurately norm items, and can provide summary statistics analogous to the traditionally reported means and SDs, but which are disentangled from participants' response biases. CLMMs can be applied to solve important statistical issues that exist for more traditional analyses of rating norms.

Multigroup invariance of the DAS across a random and an internet-sourced sample

It is well established that angry and, subsequently, aggressive drivers pose a problem for road safety. Over recent years, there has been an increase in the number of published studies examining driver anger, particularly using the Driving Anger Scale (DAS). The DAS measures six broad types of situations likely to provoke anger while driving (i.e., police presence, illegal driving, discourtesy, traffic obstructions, slower drivers, and hostile gestures). The majority of the recent studies have moved away from traditional paper-and-pencil methodologies, using the internet to collect data, for reasons of convenience. However, it is not yet completely clear whether data obtained from this methodology differs from more traditional methods. While research outside of the driving arena has not found substantial differences, it is important to establish whether this also applies to driving-related research and measures, such as the DAS. The present study used Multigroup Confirmatory Factor Analysis (MGCFA) to investigate the invariance of the DAS across a random sample from the electoral roll (n = 1,081: males = 45%) and an internet sourced sample (n = 627; males = 55%). The MGCFA showed the same six-factor solution was supported in both datasets. The relationships between the DAS factors and age, sex, trait anger, and annual mileage were broadly similar, although more significant differences were identified in the internet sample. This research demonstrates that driving measures administered over the internet produce similar results to those obtained using more traditional methods.

Addressing Prescription Discrepancies in Renal Patients: A Prospective Audit

Background

Management of chronic renal failure requires complex medication regimens to manage hypertension, hyperlipidaemia, diabetes, phosphate, anaemia and acidosis. Patient engagement in medicine management is essential to avoid potential harm.

Methods

We prospectively audited the rate of discrepancies between our hospital record of patient medications and their current prescription. We investigated whether changes to appointment letters reduced the number of discrepancies.

Results

The proportion of patients attending renal outpatient clinics failing to bring a list or unable to recall their medications fell over a 3-year period following changes to appointment letters (median proportion: 0.45 in 2014, 0.36 in 2015, 0.30 in 2016, Chi-sq = 46.94, p < 0.001); percentage of patients forgetting to bring a list with significant prescription discrepancies fell from 10.9% in 2014 to 3.9% in 2016).

Conclusion

Changes to appointment letters can potentially improve prescribing safety in an outpatient setting.

Discovery and characterization of taspoglutide, a novel analogue of human glucagon-like peptide-1, engineered for sustained therapeutic activity in type 2 diabetes

AIM

Glucagon-like peptide-1 (GLP-1) receptor agonists for the treatment of type 2 diabetes are administered by daily injection because of short plasma half-lives, which result partly from the biochemical instability of these peptides. There is a medical need for GLP-1 analogues that can be administered less frequently for patient convenience.

METHODS

We synthesized a series of human GLP-1 (hGLP-1(7-36)NH(2) ) derivatives containing α-aminoisobutyric acid (Aib) substitutions, analysed their enzymatic stabilities and evaluated their secondary structures using circular dichroism (CD) and nuclear magnetic resonance (NMR).

RESULTS

Plasma stability experiments showed that only the analogue containing Aib substitutions in both the N-terminus (position 8) and the C-terminus (position 35), [Aib⁸(,)³⁵]hGLP-1(7-36)NH₂ (BIM-51077), was fully resistant to enzymatic cleavage. Incubation with human plasma kallikrein or plasmin confirmed that the Aib substitution at position 35 prevented protease cleavage around this residue, which contributes to the significantly enhanced plasma stability and increased plasma half-life. CD revealed increased C-terminal α-helicity in Aib³⁵-substituted analogues compared with both hGLP-1(7-36)NH₂ and analogues containing only Aib⁸ substitutions. Based on NMR studies, the secondary structure of BIM-51077 is similar to hGLP-1(7-36)NH₂ with a slight increase in α-helicity in the C-terminus. Compared with hGLP-1(7-36)NH₂, BIM-51077 had similar binding affinity for the human GLP-1 receptor and activated this receptor with similar potency.

CONCLUSIONS

We have discovered an Aib⁸(,)³⁵-substituted analogue of native hGLP-1(7-36)NH₂ (BIM-51077) that retains the structure of the native peptide, and has similar activity and enhanced stability. A sustained-release formulation of this molecule (taspoglutide) is in phase-3 clinical development.

Two Unusual Cases Of Calcific Uraemic Arteriolopathy

Calcific uraemic arteriolopathy is a small vessel vasculopathy occurring almost exclusively in patients with renal failure. Violaceous mottling of the lower limbs, buttocks or lower abdomen precedes the development of painful, necrotic, non-healing ulcers. We report two atypical manifestations of calcific uraemic arteriolopathy and highlight a condition which is seen increasingly frequently as the number of patients undertaking dialysis continues to rise.

Effects of selective somatostatin analogs and cortistatin on cell viability in cultured human non-functioning pituitary adenomas

Clinically "non-functioning" human pituitary adenomas (NFPA) constitute about 35% of pituitary adenomas. Somatostatin receptors (SSTR) expression in these adenomas has previously been described both in vitro and in vivo, without evidence for a correlation with tumor volume or the therapeutic efficacy of somatostatin analogs. This study was performed on 13 surgically removed pituitary macroadenomas, diagnosed before surgery as "non-functioning". In addition, 3 growth hormone (GH)-secreting adenomas served as controls. A specimen from each tumor was dispersed and digested to isolate and culture the tumor cells, and the in vitro effects of SSTR2 and SSTR5 selective analogs and Cortistatin (CST) (100nM) on cell viability were studied. The quantity of viable cells was estimated using the XTT method. RNA purification of tumor samples and subsequent RT-PCR studies for SSTR2 and SSTR5 expression were performed. Somatostatin analog with high affinity for SSTR2 reduced cell viability by 20-80% in 8 of 13 NFPAs studied, all expressing the SSTR2. The inhibitory effect on cell viability of SSTR5-selective analog was 15-80% in 10 of 13 NFPAs studied, all but three expressing the SSTR5. CST, however, effectively reduced cell viability in only 6 NFPAs. Cell viability was inhibited by all peptides studied in 2 out of 3 GH-secreting adenomas, expressing both receptors. The third adenoma responded to SSTR2 analog and expressed only SSTR2. These results suggest the involvement of SSTR2 and SSTR5 in the anti-proliferative effects of somatostatin; however, CST is less potent in reducing cell viability in these tumors.

In vitro antiangiogenic activity of selective somatostatin subtype-1 receptor agonists

BACKGROUND

Endothelial cells of human blood vessels (arteries and veins) show high levels of somatostatin subtype-1 receptor (sst(1)). The aim of the present study is to investigate the inhibitory effects of novel somatostatin analogs, highly selective for human sst(1), on in vitro angiogenesis and their modulation of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-2 (VEGFR-2) expression.

MATERIALS AND METHODS

Somatostatin analogs BIM-23745 and BIM-23926 were tested for their ability to prevent proliferation and migration of human endothelial HMEC-1 cells, to modulate VEGF and VEGFR-2 expression and to inhibit sprouting of microvessels from cultured human placental vessel explants in fibrin matrix for 28 days.

RESULTS

The somatostatin sst(1 )receptor-selective agonists, BIM-23745 and BIM-23926 showed a suppression of endothelial proliferation (e.g. 10(-6) M BIM-23475, 40.0 +/- 2.1% vs. 100% of controls; 10(-7) M BIM-23926, 55.3 +/- 3.3% vs. 100% of controls), migration (e.g. 10(-7) M BIM-23475, 35.0 +/- 1.56% vs. 100% of controls; 10(-7) M BIM-23926, 53.7 +/- 1.77% vs. 100% of controls) and microvessel sprouting (e.g. 10(-8) M BIM-23475, 42.8 +/- 5.6% vs. 100% of controls; 10(-7) M BIM-23926, 17.2 +/- 11.8% vs. 100% of controls). A small but significant percentage of cells exposed to BIM-23745 and BIM-23926 for 24 h and for 72 h presented typical apoptotic morphology. Moreover, both the analogs significantly inhibit VEGF and VEGFR-2 gene expression in endothelial cells grown for 144 h in a fibrin matrix and the VEGF secretion in conditioned media.

CONCLUSIONS

The inhibition of endothelial activities suggests potential therapeutic utility for administration of somatostatin sst(1 )receptor-selective agonists in the proliferative diseases involving angiogenesis.

Regulation of insulin and glucagon secretion from rat pancreatic islets in vitro by somatostatin analogues

Somatostatin is an inhibitor of hormone secretion through specific receptors (sst1-5). The aim of this study was to investigate the putative regulatory role of somatostatin analogues on the secretion of insulin and glucagon by rat pancreatic islets. After 48 h exposure only the non-selective agonists (somatostatin, octreotide and SOM-230) inhibited insulin accumulation. The inhibition of insulin secretion was accompanied by increased islet insulin contents. None of the analogues showed a consistent effect on the glucagon accumulation in the medium after 48 h. Since we observed a difference in the regulatory effect between the non-selective and selective analogues, combinations of selective analogues were studied. Combination of sst2+sst5 agonists inhibited the medium insulin accumulation, while combination of sst1+sst2 analogues caused a decrease in glucagon accumulation. After removal of somatostatin a rebound effect with increased insulin secretion were observed. This effect was reversed after 6 h. For SOM-230 insulin secretion continued to be suppressed even after the analogue was removed and returned to control values after 3 h. As for glucagon secretion there was an initial decline after culture with octreotide, while the other substances failed to induce any changes. In summary, non-selective somatostatin analogues or combinations of receptor selective analogues may cause inhibition of hormone secretion from rat pancreatic islets. For insulin and glucagon, combinations of sst2+sst5 and sst1+sst2, respectively may exert this effects. Thus, our data suggest that more than one sst must be involved to down-regulate islet glucagon and insulin secretion.

Increased platelet activation in renal transplant patients

BACKGROUND

Patients with functioning renal transplants are at risk of graft thrombosis in the postoperative period, and of fistula thrombosis and other thrombotic events thereafter. Investigation and therapeutic manipulation of haemostasis in these patients offers a means to counter this thrombotic tendency.

METHODS

Platelet aggregation in whole blood, plasma von Willebrand factor and plasma fibrinogen levels were measured in 32 stable renal transplant patients (creatinine <200 micromol/litre, age of graft >4 months) and in 32 age, sex and smoking-habit matched normal controls.

RESULTS

In both patient and control groups, seven patients were smokers and the remaining 25 were non-smokers. There was no significant difference in age between patients and controls [patients, median: 39 (20-64) years; controls: 38 (24-60) years]. Spontaneous platelet aggregation was significantly higher in the patients at all time points studied [30s-6 min; at 4 min: patients median (interquartile range) 19.4 (11.3-27.3)%; controls, 8.0 (5.1-15.0)%, P < 0.0005]. ADP-induced aggregation was also increased at a concentration range of 0.1-3 microM (at 1 microM, 1 min, patients median (interquartile range) was 52.4 (30.5-70.0)%; controls was 16.5 (1.4-31.4)%, P < 0.0001). Transplant patients had significantly higher von Willebrand factor and fibrinogen levels compared with the controls (von Willebrand factor, patients median (range): 158 (13-269)%; controls: 85 (43-223)%, P < 0.00001; fibrinogen, patients: 3.29 (2.12-7.39) g/litre; controls: 2.81 (1.84-4.65) g/litre, P < 0.0002).

CONCLUSION

Patients with stable renal transplants have in vitro evidence of enhanced platelet activation, and increased plasma von Willebrand factor and fibrinogen levels.

Does metabolic syndrome mitigate weight loss in overweight Mexican American women treated for 1-year with orlistat and lifestyle modification?

AIMS

To investigate the effects of a pharmacotherapy (orlistat) plus lifestyle management (OLM) intervention on weight loss in Mexican American women with and without metabolic syndrome (MS).

METHODS

One hundred and seven female participants aged 21-65 years and of Mexican origin were randomized to either OLM or a wait-list control group (WLC) for one year. The lifestyle interventions were tailored to exhibit features of the Mexican culture. Within each group, subjects with MS were compared to those without MS to assess whether its presence mitigates weight loss. Risk factors for MS also were assessed.

RESULTS

Participants with MS in the OLM group experienced significant decreases in weight and body mass index (BMI) as compared to participants without MS. Participants with MS in the OLM group and who completed the study lost 9.3+/-7.5 kg (20.5+/-16.5 lb) as compared to participants with MS in the WLC group, who only lost 0.2+/-3.1 kg (0.4+/-6.8 lb). Further, participants with MS in the OLM group who completed the study experienced a 3.1+/-3.9 kg/m2 decrease in BMI whereas participants with MS in the WLC group only experienced a 0.1+/-1.2 kg/m2 decrease in BMI. No changes in other MS risk factors were significant.

CONCLUSIONS

Patients with MS experienced significant weight loss and decreases in BMI as a result of a lifestyle and pharmacotherapy intervention.

Detecting fMRI activation allowing for unknown latency of the hemodynamic response

Several authors have suggested allowing for unknown latency of the hemodynamic response by incorporation of hemodynamic derivative terms into the linear model for the statistical analysis of fMRI data. In this paper, we show how to use random field theory to provide a P value for local maxima of two test statistics that have been recently proposed for detecting activation based on this analysis.

Brain-derived neurotrophic factor promotes bovine oocyte cytoplasmic competence for embryo development

The ability of an oocyte to support early embryonic development requires both nuclear and cytoplasmic maturation. We have investigated the effects of brain-derived neurotrophic factor (BDNF) on maturation of the bovine oocyte and embryo development after parthenogenetic activation. By RT-PCR and immunohistochemistry, cumulus and oocytes were shown to express mRNA and protein for BDNF and the p75 common neurotrophin receptor. However, mRNA for the BDNF-specific full length and truncated isoforms of the TrkB receptor are only detected in cumulus, suggesting that oocytes and cumulus differ in their capacity to respond to neurotrophin signalling. Inin vitromaturation experiments, the proportion of cumulus oocyte complexes maturing to metaphase II was not altered by BDNF in groups lacking fetal calf serum (FCS), but was significantly lower than the positive control containing 10% FCS (P< 0.01). However, after maturation, the proportion of parthenogenetically activated oocytes forming blastocysts was highest for 10 ng/ml BDNF (24%,n= 95) followed by 100 ng/ml BDNF (18%,n= 91) and 10% FCS (15%,n= 103), which in turn were greater than no serum (10%,n= 83;P< 0.01). Maturation in the presence of a BDNF blocking antibody resulted in a blastocyst yield that was comparable to the absence of serum, and lower than in the presence of BDNF (P< 0.01). Similar effects on progression to metaphase II and blastocyst formation were observed using oocytes matured without cumulus. Together, these results provide the first evidence for a role for neurotrophins in promoting oocyte cytoplasmic competence to support embryonic development, despite being insufficient in the absence of serum to enhance nuclear maturation.

Novel ghrelin analogs with improved affinity for the GH secretagogue receptor stimulate GH and prolactin release from human pituitary cells

OBJECTIVE

Ghrelin, a recently identified 28-amino acid peptide is a potent GH secretagogue (GHS) produced predominantly by the stomach. Ghrelin stimulates GH secretion through binding to the GHS receptor in the hypothalamus and pituitary. In addition to the GH-releasing action, ghrelin has been found to be a powerful orexigenic factor. To assess the direct in vitro effects of ghrelin on human pituitary hormone secretion we have produced a panel of novel ghrelin analogs (molecular weight, 3323-3384; human native ghrelin, 3371) with enhanced affinity for the human GHS receptor (IC(50) 0.38-1.09 nM; human ghrelin, 1.2-2.2 nM).

METHODS

The peptidic analogs were tested for their effect on GH secretion using dispersed human fetal pituitaries (21 to 23 weeks of gestation) and cultured GH- and prolactin (PRL)-secreting adenomas. The expression of the GHS receptor in normal (fetal and adult) human pituitary tissues, GH- and PRL-cell adenomas was established using RT-PCR.

RESULTS

The effects of ghrelin, its analogs and GH-releasing hormone (GHRH) alone or in combination on GH and PRL secretion were compared at various concentrations. The ghrelin analogs stimulated GH release by 35-60% from human fetal pituitary cells (1-10 nM; P<0.05) and by 50-75% from cultured pituitary adenomas (10 nM; P<0.05). This releasing effect was dose-dependent, achieving maximal stimulation with analog concentrations at 100 nM. Human ghrelin was less potent as compared with its analogs in stimulating human GH, in keeping with the improved binding affinity of the analogs for the GHS-1a receptor. The ghrelin analogs and GHRH had comparable effects on GH secretion from both normal and adenomatous cells, and in combination produced an additive stimulatory effect on GH (150%; P<0.0001). In contrast, ghrelin and its analogs induced a comparable increase in PRL release ranging between 25 and 40% (P<0.05) from fetal cells and 30 and 70% (P<0.001) from cultured PRL-cell and mixed GH-PRL adenomas.

CONCLUSIONS

Our results have demonstrated for the first time that ghrelin analogs with enhanced affinity for the GHS receptor are potent stimulators of GH secretion from human pituitary cells, and thus may possess potential clinical therapeutic benefits.

Life-saving skills training for midwives: report on the Ghanaian experience

The shortage of rural-based physicians in Ghana has led to a decision to provide short term courses to rural midwives on the treatment of those obstetric conditions that are the main causes of maternal mortality. A description of this ongoing training is provided.

Expression and function of somatostatin receptor subtype 1 in human growth hormone secreting pituitary tumors deriving from patients partially responsive or resistant to long-term treatment with somatostatin analogs

The role of somatostatin (SS) receptor subtype 1 (SSTR(1)) in mediating the inhibitory effect of SS on growth hormone (GH) secreting pituitary tumors has been recently demonstrated. In the present study, we evaluated the effect of the selective SSTR(1) agonist BIM-23745 on in vitro GH secretion in GH-secreting pituitary tumor cells, deriving from patients resistant or partially responsive to octreotide long-acting release (octreotide-LAR) or lanreotide therapy in vivo and expressing SSTR(1) mRNA. In addition, the inhibiting effect of BIM-23745 on the GH secretion was compared with that of octreotide. Our data demonstrate that (1) SSTR(1) receptor was present in 56.25% (9/16) of the GH-secreting adenomas examined; (2) in all GH-secreting pituitary tumors that expressed SSTR(1), BIM-23745 significantly inhibited GH secretion in vitro, and (3) when SSTR(1) subtype was present in tumors from patients resistant to octreotide-LAR or lanreotide therapy, BIM-23745 was able to inhibit the in vitro GH secretion. In conclusion, the results of the current study suggest that SS analogs selective for the SSTR(1) may represent a further useful approach for the treatment of acromegaly in patients resistant or partially responsive to octreotide-LAR or lanreotide treatment in vivo.

Weight loss in obese Mexican Americans treated for 1-year with orlistat and lifestyle modification

OBJECTIVE

To evaluate the effectiveness of a culturally appropriate lifestyle intervention combined with orlistat in producing weight loss with obese Mexican-American women.

SUBJECTS

Mexican-American women (N=108), aged 21-65 y, with a body mass index (BMI) > or =27 kg/m(2) were randomized to 1 y of treatment with orlistat and a culturally tailored lifestyle modification intervention (OLM; n=56) or a wait-list control group (WLC; n=52).

DESIGN

A randomized, controlled, open-label 12-month study. Orlistat was dosed at 120 mg, three times per day. The OLM intervention included behavior modification, a low-fat (< or =30% of total daily calories) diet, and moderate physical activity (> or =150 min/week).

MEASUREMENT

Primary outcomes included changes in body weight (kg), BMI, waist circumference, blood pressure, glucose, and lipids.

RESULTS

A total of 72 (37 OLM, 35 WLC) and 66 participants (32 OLM, 34 WLC) completed the 6- and 12-month follow-ups, respectively. Repeated-measures ANOVA demonstrated a significant time x treatment interaction (Wilks' lambda=12.61; P<0.001), indicating that OLM-treated patients achieved significant weight loss relative to the WLC group during the study (mean percentage weight loss+/-s.e.m.; -8.1%+/-1.2 vs -1.6%+/-0.7 at 6 months and -8.8%+/-1.5 vs -0.2%+/-1.0 at 12 months, respectively). OLM-treated patients also experienced significant reductions in waist circumference, low-density-lipoprotein, and total cholesterol.

CONCLUSIONS

This study demonstrates the effectiveness of an intervention combining orlistat and lifestyle modification with Mexican-American women, a population with substantial risk for obesity.

Psychometric characteristics of the General Well-Being Schedule (GWB) with African-American women

The General Well-Being Schedule (GWB) is a brief, reliable, and valid instrument used in population studies to assess psychological well-being, although its validity with African-Americans has yet to be established. This study evaluated the reliability, validity, and factor structure of the GWB in a sample of 599 overweight African-American women who participated in multicenter weight loss trial. The results of the factor analysis indicate that the GWB is primarily unidimensional and that the existence of the six hypothesized subscales was not supported. The GWB demonstrated evidence of concurrent and construct validity when examined in association with measures of self-concept, depression, and several health behaviors. The results of this study suggest that the GWB is a reliable and valid measure of psychological well-being in African-American women.

Structural requirements at the N-terminus of urotensin II octapeptides

Urotensin II is the latest of a growing list of peptides exhibiting potent cardiovascular effects. It is an extremely potent vasoconstrictor in primates; its excretion is elevated in hypertensive patients thus suggesting therapeutic potential for urotensin II analogues, particularly receptor antagonists. In the present study, a number of interesting structural features pertaining to the N-terminus of urotensin II have been evaluated for binding to cloned human and rat urotensin II receptors and functional effects on rat upper thoracic aorta smooth muscle preparations. Shortened octapeptides retained full binding affinities and functional activities, did not require a free N-terminal amino group, and could tolerate an amidated C-terminus. The N-terminal Asp residue present in the octapeptides did not require a negatively charged side chain, merely one which contained a hydrogen bond acceptor CO group which could be present at a variety of positions on the side chain. The side chain could be constrained into a trans-olefinic configuration with full retention of potency, but potency was lost in the cis configuration. N-terminal aromatic amino substituted with polar groups such as OH and NO(2) also resulted in high affinity analogues. Overall, the correlation between binding affinities for the human and rat receptors was quite good. These findings could be of value in the development of more potent urotensin II receptor antagonists based on the previously identified somatostatin antagonist octapeptides which we have recently found, function as relatively weak urotensin II antagonists.

Demonstration of enhanced potency of a chimeric somatostatin-dopamine molecule, BIM-23A387, in suppressing growth hormone and prolactin secretion from human pituitary somatotroph adenoma cells

In acromegaly, the combination of somatostatin (SS) and dopamine (DA) agonists has been shown to enhance suppression of GH secretion. In the present study, a new chimeric molecule, BIM-23A387, which selectively binds to the SS subtype 2 receptor (sst(2); K(i) = 0.10 nM) and to the DA D2 receptor (D2DR; K(i) = 22.1 nM) was tested in cultures prepared from 11 human GH-secreting tumors for its ability to suppress GH and prolactin (PRL) secretion. The chimeric compound was compared with individual sst(2) and D2DR agonists of comparable activity at the individual receptors. All tumors expressed both sst(2) and D2DR mRNAs (0.8 +/- 0.2 and 4.7 +/- 0.7 copy/copy beta-glucuronidase mRNA, respectively). In cell cultures from seven octreotide-sensitive tumors, the maximal inhibition of GH release induced by the individual sst(2) and D2DR analogs and by BIM-23A387 was similar. However, the mean EC(50) for GH suppression by BIM-23A387 (0.2 pM) was 50 times lower than that of the individual sst(2) and D2DR analogs, either used individually or combined. Similar data were obtained in four tumors that were only partially responsive to octreotide. The inhibition of GH release by BIM-23A387 was only partially reversed by the D2R2 antagonist, sulpiride, or by the sst(2) antagonist, BIM-23454. Only when both antagonists were combined was the GH suppressive effect of BIM-23A387 totally reversed. Finally, BIM-23A387 produced a mean 73 +/- 6% inhibition of PRL in six mixed GH plus PRL tumors. These data demonstrate an enhanced potency of the chimeric molecule, BIM-23A387, in suppressing GH and PRL secretion from acromegalic tumors, which cannot be explained merely on the basis of binding affinity for SS and/or DA receptors.

Somatostatin, but not somatostatin receptor subtypes 2 and 5 selective agonists, inhibits calcitonin secretion and gene expression in the human medullary thyroid carcinoma cell line, TT

Somatostatin (SRIH) analogs are commonly used to treat symptoms in medullary thyroid carcinoma (MTC), that expresses SRIH receptors (SSTR1 to SSTR5), as does the human MTC cell line TT. The aim of this work was to evaluate whether SRIH, SSTR2 and SSTR5-selective agonists influence calcitonin (CT) secretion and gene expression in the TT cell line. CT secretion was evaluated by chemiluminescence, and gene expression was analyzed by Northern blot. TT cell line proliferation was also assessed by [(3)H] thymidine ([(3)H]thy) incorporation and viable cell number count. SRIH significantly (p < 0.05) reduced [(3)H]thy incorporation (approx. 50 %), viable cell number (approx. 20 %), CT secretion (-30 %) and CT gene expression (approx. 2-fold). Exposure to the SSTR2-selective agonist, BIM-23 120, and to the SSTR5-selective agonist, BIM-23 206, did not modify CT secretion and mRNA levels in TT cells. Thus, SRIH inhibits DNA synthesis, cell proliferation, CT secretion and CT gene expression in the TT cell line, while SSTR2 and 5 selective agonists, although influencing DNA synthesis and cell proliferation, do not modify CT gene expression, suggesting that SRIH may influence gene expression acting through SSTRs other than subtypes 2 and 5. Furthermore, these findings may explain the erratic response of MTC patients in terms of CT plasma levels to treatment with SRIH analogs, like octreotide and lanreotide, which interact mainly with SSTR2 and 5.

Characterization of new selective somatostatin receptor subtype-2 (sst2) antagonists, BIM-23627 and BIM-23454. Effects of BIM-23627 on GH release in anesthetized male rats after short-term high-dose dexamethasone treatment

We here report a pharmacological characterization of two new somatostatin (SS) receptor subtype-2 (sst2) selective antagonists by evaluating their GH-releasing activity when administered, by different routes, in anesthetized adult rats and in freely moving 10-d-old rats. Moreover, we describe the effect of these SS antagonists on the GH response to GHRH after short-term high-dose dexamethasone (DEX) treatment in young male rats. BIM-23454 and BIM-23627, given iv, were able to counteract the SS-induced inhibition of GH secretion occurring after urethane anesthesia in a dose-dependent manner. In DEX-treated animals, the GH response to GHRH was partially blunted (5-min peak values, 270 +/- 50 ng/ml in saline-treated vs. 160 +/- 10 ng/ml in DEX-treated, P < 0.05); however, the simultaneous administration of BIM-23627 (0.2 mg/kg, iv) restored higher amplitude GH pulse, leading to a significantly higher overall mean GH response (area under the curve, 4200 +/- 120 ng/ml/30 min vs. 2800 +/- 100 ng/ml/30 min after GHRH alone; P < 0.05). The SS antagonists showed a reduced GH-releasing effect when administered sc or ip, likely attributable to decreased bioavailability, as compared with the iv route. SS antagonist administration also increased plasma glucagon, insulin, and glucose levels. Based on prior reports that sst2 tonically suppresses glucagon secretion, the antagonist most likely increased glucagon secretion from the pancreatic alpha-cells, with resultant increases in plasma glucose and then insulin.

Somatostatin receptor subtypes: targeting functional and therapeutic specificity

Somatostatin is a regulatory peptide involved in a wide variety of biological functions throughout the body. A key physiological question, as well as the challenge to developing somatostatin-based therapeutics, is how functional specificity can be conferred in such a widespread, multifunctional hormonal system. With the discovery of distinct subtypes of the somatostatin receptor, we have attempted to elucidate the manner in which somatostatin selectively regulates specific biological functions using panels of somatostatin analogs that have been fully characterized for their unique selectivity and specificity for the various receptor subtypes. By testing these selective analogs in well-established biological assay systems, we and our collaborators have revealed functional interactions between the somatostatin receptor subtypes that can either potentiate or antagonize the cellular response to somatostatin. These observations have resulted in several novel concepts for treating acromegaly that should offer greater efficacy to a larger percentage of patients than current therapeutic options. Further, these studies are providing evidence of interaction between the somatostatin receptor subtypes and receptors of other G-protein-coupled receptor families. These various levels of interaction provide a means by which the cellular response to somatostatin can be exquisitely controlled and modified by both physiological status and disease. Greater understanding of these interactions will provide the conceptual basis for future therapeutics with enhanced efficacy and with greater cellular and functional specificity.

Sexual network structure as an indicator of epidemic phase

Ascertaining epidemic phase for a sexually transmitted disease (STD) has depended on secular trend data which often contain significant artefacts. The usefulness of sexual network structure as an indicator of STD epidemic phase is explored in an analysis of community wide genital chlamydia reports, with network analysis of interviewed cases and linked sexual partners, in Colorado Springs, USA, 1996 to 1999. In this period, the chlamydia case rate per 100,000 increased by 46%. Three quarters of cases (n=4953) were interviewed, nominating 7365 partners; these, combined with index cases, made up the 9114 persons in the network. Epidemiologic analysis of cases suggests that secular trend increases are artefactual. Network analysis supports this view: overall network structure is fragmented and dendritic, notably lacking the cyclic (closed loops) structures associated with network cohesion and thus with efficient STD transmission. Comparison of network structure with that of an intense STD outbreak (characterised by numerous cyclic structures) suggests low level or declining endemic rather than epidemic chlamydia transmission during the study interval. These observations accord with intuitive and stochastic predictions.

Rash, abdominal pain and hyponatraemia

Hypertriglyceridaemia is a rare precipitant of acute pancreatitis. We present a patient with acute pancreatitis and hyponatraemia in association with severe hyperlipidaemia, predominantly hypertriglyceridaemia. The patient was successfully treated with plasma exchange therapy.

The interaction of culture with general job stressors in air traffic controllers

Elements of the job of Air Traffic Controllers perceived as being stressful were rated for degree of stressfulness by a group of Singaporean controllers. The results were compared with those from earlier studies in Canada and New Zealand. It was hypothesized that the international nature of the job would be reflected in findings from all three groups of controllers. It was further hypothesized, however, that environmental and cultural factors would produce differences among the groups and that these would be greater between the Asian and the two "Western" cultures than between the two earlier samples studied. Results showed that the two Western cultures share 56% common variance in their perceptions of stressfulness, but this changes to 35% between the New Zealand and Singapore groups and only 21% between Canada and Singapore. Although comparison of the factor structure of the stress ratings of the Singapore and New Zealand samples again confirmed a general pattern of underlying stressors related to air traffic control (which fits general occupational models of stress), it also revealed culturally specific components. The nature of these suggests that they are emhedded in the context of Asian environments and cultures. The conclusion is that stress in Air Traffic Controllers is related both to generic occupation stressors and to others that are both organizationally and culturally specific.

GI side-effects of a possible therapeutic GRF analogue in monkeys are likely due to VIP receptor agonist activity

Growth hormone (GH) is used or is being evaluated for efficacy in treatment of short stature, aspects of aging, cardiac disorders, Crohn's disease, and short bowel syndrome. Therefore, we synthesized several stable growth hormone-releasing factor (GRF) analogues that could be therapeutically useful. One potent analog, [D-Ala(2),Aib(8, 18,)Ala(9, 15, 16, 22, 24-26,)Gab(27)]hGRF(1-27)NH(2) (GRF-6), with prolonged infusion caused severe diarrhea in monkeys; however, it had no side-effects in rats. Because GRF has similarity to VIP/PACAP and VIPomas cause diarrhea, this study investigated the ability of this and other GRF analogues to interact with the VIP/PACAP receptors. Rat VPAC(1)-R (rVPAC(1)-R), human VPAC(1)-R (hVPAC(1)-R), rVPAC(2)-R and hVPAC(2)-R stably transfected CHO and PANC 1 cells were made and T47D breast cancer cells containing native human VPAC(1)-R and AR4-2J cells containing PAC(1)-R were used. hGRF(1-29)NH(2) had low affinity for both rVPAC(1)-R and rVPAC(2)-R while VIP had a high affinity for both receptors. GRF-6 had a low affinity for both rVPAC(1)-R and rVPAC(2)-R and very low affinity for the rPAC(1)-R. VIP had a high affinity, whereas hGRF(1-29)NH(2) had a low affinity for both hVPAC(1)-R and hVPAC(2)-R. In contrast GRF-6, while having a low affinity for hVPAC(2)-R, had relatively higher affinity for the hVPAC(1)-R. In guinea pig pancreatic acini, all GRF analogues were full agonists at the VPAC(1)-R causing enzyme secretion. These results demonstrate that in contrast to native hGRF(1-29)NH(2,) GRF-6 has a relatively high affinity for the human VPAC(1)-R but not for the human VPAC(2)-R, rat VPAC(1)-R, rat VPAC(2)-R or rat PAC(1)-R. These results suggest that the substituted GRF analog, GRF-6, likely causes the diarrheal side-effects in monkeys by interacting with the VPAC(1)-R. Furthermore, they demonstrate significant species differences can exist for possible therapeutic peptide agonists of the VIP/PACAP/GRF receptor family and that it is essential that receptor affinity assessments be performed in human cells or from a closely related species.

Somatostatin receptor subtypes 2 and 5 differentially affect proliferation in vitro of the human medullary thyroid carcinoma cell line tt

Somatostatin and its receptors (SSTR1 to SSTR5) are expressed in normal human parafollicular C cells and medullary thyroid carcinoma (MTC), but the role of SSTR subtypes in cell growth regulation is still not clear. The present study demonstrates that the human MTC cell line TT stably expresses all the SSTR subtypes and responds to SSTR2 and SSTR5 activation by subtype-selective agonists with two different patterns in terms of [(3)H]thymidine ([(3)H]thy) incorporation and cell number. The SSTR2 preferential agonists (BIM-23120, BIM-23197, BIM-23190, and BIM-23014; 10(-9)-10(-6) M), significantly suppressed [(3)H]thy incorporation (58-13%) and reduced cell proliferation (50-28%), whereas the SSTR5-selective agonist, BIM-23206 (10(-9)-10(-6) M), significantly increased [(3)H]thy incorporation in TT cells (80-175%), but failed to influence cell proliferation. SSTR2 antagonist (BIM-23627) counteracted the action of SSTR2 preferential agonists on TT cells. Furthermore, increasing concentrations of SSTR5-selective agonists, BIM-23206, dose-dependently prevented the suppression of TT cell [(3)H]thy incorporation and proliferation produced by SSTR2 preferential agonist, BIM-23120, showing an antagonism between these compounds. The following conclusions were reached: 1) the human MTC cell line TT expresses all SSTR subtypes; 2) SSTR2 activation inhibits DNA synthesis and cell proliferation, whereas SSTR5 activation increases DNA synthesis; and 3) SSTR2 preferential agonist (BIM-23120) can antagonise SSTR5-selective agonist (BIM-23206) action and vice versa. These findings suggest a tissue-specific function and a tissue-specific interaction between the two receptors.

The role of calcium in ABA-induced gene expression and stomatal movements

There is much interest in the transduction pathways by which abscisic acid (ABA) regulates stomatal movements (ABA-turgor signalling) and by which this phytohormone regulates the pattern of gene expression in plant cells (ABA-nuclear signalling). A number of second messengers have been identified in both the ABA-turgor and ABA-nuclear signalling pathways. A major challenge is to understand the architecture of ABA-signalling pathways and to determine how the ABA signal is coupled to the appropriate response. We have investigated whether separate Ca2+-dependent and -independent ABA-signalling pathways are present in guard cells. Our data suggest that increases in [Ca2+]i are a common component of the guard cell ABA-turgor and ABA-nuclear signalling pathways. The effects of Ca2+ antagonists on ABA-induced stomatal closure and the ABA-responsive CDeT6-19 gene promoter suggest that Ca2+ is involved in both ABA-turgor signalling and ABA-nuclear signalling in guard cells. However, the sensitivity of these pathways to alterations in the external calcium concentration differ, suggesting that the ABA-nuclear and ABA-turgor signalling pathways are not completely convergent. Our data suggest that whilst Ca2+-independent signalling elements are present in the guard cell, they do not form a completely separate Ca2+-independent ABA-signalling pathway.

N-Methyl scan of somatostatin octapeptide agonists produces interesting effects on receptor subtype specificity

The search for synthetic analogues of somatostatin which exhibit selective affinities for the five receptor subtypes is of considerable basic and therapeutic interest and has generated a large number of potent agonist analogues with a wide spectrum of binding profiles. In the past, conformational restriction of side chain groups and the peptide backbone has yielded the most interesting results. Under the latter category and as part of the present study, we were interested in the potential effects of N-methylation of peptide bond NH groups on binding affinity since this approach had not been systematically examined with these peptides. This was aided by new chemistries for introducing an N-Me group during regular solid-phase peptide synthesis using Boc protection. A number of interesting effects were noted on relative binding affinities of the two series of agonist sequences chosen, DPhe(5)(or Tyr(5))-c[Cys(6)-Phe(7)-DTrp(8)-Lys(9)-Thr(10)-Cys(11)]Thr(12)-NH(2) (SRIF numbering), at the five known human somatostatin receptors transfected into and stably expressed by CHO cells. N-Methylation of residues 7 (Phe), 10 (Thr), 11 (Cys), and 12 (Thr) largely destroyed affinities for all five receptors. N-Methylation of DTrp in the DPhe series gave an analogue with extraordinarily high affinity for the type 5 receptor for which it was also quite selective. N-Methylation of Lys in both series resulted in retention of type 2 affinity despite this residue constituting the "active center" of somatostatin peptides. N-Methylation of either the N-terminal Tyr residue or of Cys(6) in the Tyr series resulted in analogues with extraordinarily high affinity for the type 3 receptor, also with a degree of specificity. N-Methylation of the peptide bond constrains the conformational space of the amino acid and eliminates the possibility of donor hydrogen bond formation from the amide linkage. The beta-bend conformation of the agonists around DTrp-Lys is stabilized by a transannular intramolecular hydrogen bond(s) between Phe(7) and Thr(10) so methylation of these residues eliminates this source of stabilization. It is expected that several of these analogues will provide additional tools for determining some of the physiological roles played by type 3 and 5 somatostatin receptors which are still far from being fully elucidated.

Highly potent and subtype selective ligands derived by N-methyl scan of a somatostatin antagonist

The search for synthetic peptide analogues of somatostatin (SRIF) which exhibit selective affinities for the five known receptor subtypes (sst1-5) has generated a large number of potent agonists. Some of these agonists display good subtype selectivities and affinities for the subtypes 1, 2, 3, and 5, including analogues created by N-methyl amino acid substitutions in a standard octapeptide analogue format. We have now extended this peptide backbone N-methylation approach to a potent somatostatin receptor antagonist series using the antagonist Cpa-cyclo(DCys-Pal-DTrp-Lys-Thr-Cys)-Nal-NH2 9 reported from this laboratory as the lead structure. Synthetic analogues were tested for their ability to inhibit somatostatin-stimulated GH release from rat pituitary cells in culture and to displace 125I-labeled somatostatin from CHO cells transfected with the five known human somatostatin receptors. Several interesting observations resulted from the study. N-Methylation at the Lys(9) residue (5) increased the rat GH release inhibitory potency nearly 4-fold to 0.73 nM but resulted in little change in the binding affinity for human type 2 receptor. This analogue also had a high affinity of 5.98 nM for sst5 receptor (compared to 1.4 nM for somatostatin itself) and is the first antagonist analogue to be reported with high affinity for sst5. It also had high potency on in vitro inhibition of sst5 mediated intracellular calcium mobilization. These results were considered surprising, since the Lys(9) residue has long been considered to constitute the active center of somatostatin, important both for receptor binding and activation, and suggests important conformational differences between D-Cys(9) somatostatin antagonists and normal agonist structures. More modifications were carried out on this analogue with the aim of improving antagonist potency and/or specificity. Tyr(7) substitution of 5 resulted in an analogue, which had the highest affinity in the series for hsst2 (K(I) 5.51 nM) and an extraordinarily low IC50 of 0.53 nM in the rat pituitary cell assay. However, this analogue lost considerable affinity for sst5 relative to analogue 5. Analogue 16 with DTrp(12) at C-terminus had the highest affinity for hsst2, however, the IC50 in the rat GH release assay was only 11.6 nM. Replacement of Lys(9) in 9 with Dab(9) gave 11 which displayed high binding affinity for sst3, and it was also quite selective for that receptor. Both the sst3 and sst5 antagonists should be of value in assigning the physiological roles to type 3 and 5 receptor, respectively.

Selective stimulation of somatostatin receptor subtypes: differential effects on Ras/MAP kinase pathway and cell proliferation in human neuroblastoma cells

In previous studies we have showed that somatostatin (SST) inhibits cell division, mitogen-activated protein (MAP) kinase and Ras activity in the human neuroblastoma cell line SY5Y. In the present study, we have assessed the role of a series of SST analogs, three of which were selective for SSTR1, SSTR2 or SSTR5, in these cellular events. All the analogs inhibited forskolin-induced cAMP accumulation. Selective stimulation of SSTR1 or SSTR2 but not of SSTR5 inhibited platelet-derived growth factor (PDGF)-induced [(3)H]thymidine incorporation. The three analogs inhibited PDGF-stimulated MAP kinase activity, at least at an early time. In contrast, none of the analogs used individually was able to inhibit PDGF-stimulated Ras activity. A combined stimulation of SSTR2 and SSTR5 was necessary to obtain a significant inhibitory effect, suggesting the possibility of receptor heterodimerization. These results indicate that SST inhibition of Ras and MAP kinase activities takes place via different pathways and that SST inhibition of PDGF-induced cell proliferation occurs via a Ras-independent pathway.

Structure-activity studies including a Psi(CH(2)-NH) scan of peptide YY (PYY) active site, PYY(22-36), for interaction with rat intestinal PYY receptors: development of analogues with potent in vivo activity in the intestine

Peptide YY (PYY) is a gut hormone that inhibits secretion and promotes absorption and growth in the intestinal epithelium. We have performed structure-activity studies with the active site, N-alpha-Ac-PYY(22-36)-NH(2), for interaction with intestinal PYY receptors. Investigation of aromatic substitutions at position 27 resulted in analogues that exhibited potent in vitro antisecretory potencies with N-alpha-Ac-[Trp(27)]PYY(22-36)-NH(2) exhibiting even greater potency than intact PYY. In vivo studies in dogs revealed that this analogue also promoted intestinal absorption of water and electrolytes during continuous intravenous and intraluminal infusion. Investigations carried out to identify features that would enhance stability revealed that incorporation of Trp(30) increased affinity for PYY receptors. A "CH(2)-NH" scan revealed that incorporation of reduced bonds at position 28-29 or 35-36 imparted greater receptor affinity. In general, disubstituted analogues designed based on the results of single substitutions exhibited good receptor affinity with N-alpha-Ac-[Trp(27),CH(2)-NH(35-36)]PYY(22-36)-NH(2) having the greatest affinity (IC(50) = 0.28 nM). Conservative multiple substitutions with Nle-->Leu and Nva-->Val also imparted good affinity. An analogue designed to encompass most of the favored substitutions, N-alpha-Ac-[Nle(24,28),Trp(30),Nva(31), CH(2)-NH(35-36)]PYY(22-36)-NH(2), exhibited a proabsorptive effect in dogs comparable to, but longer lasting than, that of intact hormone. Selected analogues also exhibited good antisecretory potencies in rats with N-alpha-Ac-[Trp(30)]PYY(22-36)-NH(2) being even more potent than PYY. However, the potencies did not correlate well with the PYY receptor affinity or the proabsorptive potencies in dogs. These differences could be due to species effects and/or the involvement of multiple receptors and neuronal elements in controlling the in vivo activity of PYY compounds. PYY(22-36) analogues exhibited good affinity for neuronal Y2 receptors but poor affinity for Y1 receptors. Also, crucial analogues in this series hardly bound to Y4 and Y5 receptors. In summary, we have developed PYY(22-36) analogues which, via interacting with intestinal PYY receptors, promoted potent and long-lasting proabsorptive and antisecretory effects in in vivo models. These compounds or analogues based on them may have useful clinical application in treating malabsorptive disorders observed under a variety of conditions.

Determining the focus of driving fears

Fear of driving has been recognized as a complex diagnostic entity. Studies on flying phobia have drawn similar conclusions, although increasing clarity has been gained through research that indicates that there may be subtypes of flying phobia based on the focus of fear. However, it is unclear if similar subtypes exist for fear of driving. The aim of the present study was to conduct a preliminary investigation of driving fear subtypes and to clarify further whether there were differences between driving-fearful respondents who had been in a motor vehicle accident (MVA) and those who had not. Eighty-five driving-fearful, media-recruited respondents completed a questionnaire that assessed anxiety, avoidance, and concerns related to their driving fears. The sample had high expectations of negative events while driving. There were no significant differences between those who had experienced an MVA and those who had not on various measures of fear severity. Cluster analysis revealed two main foci of fear, one characterized by danger expectancies and the other based on anxiety expectancies and unpleasant driving situations. This emphasizes the importance of assessing both internal and external foci of fear. Although this finding is consistent with the results obtained for flying phobia, more research is required to replicate and extend these results and to develop and evaluate differential treatment programs.

Coping with multiple enemies: an integration of molecular and ecological perspectives

How plants respond to attack by the range of herbivores and pathogens that confront them in the field is the subject of considerable research by both molecular biologists and ecologists. However, in spite of the shared focus of these two bodies of research, there has been little integration between them. We consider the scope for such integration, and how greater dialogue between molecular biologists and ecologists could advance understanding of plant responses to multiple enemies.

Chemical synthesis and receptor binding of catfish somatostatin: a disulfide-bridged beta-D-Galp-(1-->3)-alpha-D-GalpNAc O-glycopeptide

The glycopeptide hormone catfish somatostatin (somatostatin-22) has the amino acid sequence H-Asp-Asn-Thr-Val-Thr-Ser-Lys-Pro-Leu-Asn-Cys-Met-Asn-Tyr-Phe-Trp-Lys-Se r-Arg-Thr-Ala-Cys-OH; it includes a cyclic disulfide connecting the two Cys residues, and the major naturally occurring glycoform contains D-GalNAc and D-Gal O-glycosidically linked to Thr5. The linear sequence was assembled smoothly starting with an Fmoc-Cys(Trt)-PAC-PEG-PS support, using stepwise Fmoc solid-phase chemistry. In addition to the nonglycosylated peptide, two glycosylated forms of somatostatin-22 were accessed by incorporating as building blocks, respectively, Nalpha-Fmoc-Thr(Ac3-alpha-D-GalNAc)-OH and Nalpha-Fmoc-Thr(Ac4-beta-D-Gal-(1-->3)-Ac2-alpha-D-GalNAc)-O H. Acidolytic deprotection/cleavage of these peptidyl-resins with trifluoroacetic acid/scavenger cocktails gave the corresponding acetyl-protected glycopeptides with free sulfhydryl functions. Deacetylation, by methanolysis in the presence of catalytic sodium methoxide, was followed by mild oxidation at pH 7, mediated by Nalpha-dithiasuccinoyl (Dts)-glycine, to provide the desired monomeric cyclic disulfides. The purified peptides were tested for binding affinities to a panel of cloned human somatostatin receptor subtypes; in several cases, presence of the disaccharide moiety resulted in 2-fold tighter binding.

Chlamydia transmission: concurrency, reproduction number, and the epidemic trajectory

To identify factors that influence individual and group transmission of Chlamydia, the authors conducted community-wide contact tracing of chlamydia cases in Colorado Springs, Colorado, from mid-1996 to mid-1997. Case patients identified persons with whom they had had contact during the 6 months preceding diagnosis; contacts were actively sought and offered DNA amplification testing. Sexual contact networks were used to identify "source cases" and "spread cases," permitting estimation of the basic reproduction number (R0) for individuals and groups. Network and epidemiologic factors influencing R0 were assessed using univariate and multivariate procedures. Of 1,309 case patients, 1,131 (86%) were interviewed, and 2,409 contacts were identified. The 1,131 interviewed cases yielded 623.9 computed spread cases, for an overall R0 of 0.55. Few subgroups analyzed yielded a mean R0 exceeding unity-an observation in keeping with routine surveillance information which suggests that chlamydia incidence is declining in Colorado Springs. Concurrency, a network measure of simultaneous partnerships, was the most powerful predictor of transmission. Direct estimation of basic reproduction numbers for chlamydia using contact tracing techniques is feasible and can produce useful data with which to prioritize control efforts, evaluate interventions, and gauge the place of chlamydia on the epidemic continuum.

Determination of eletriptan in plasma and saliva using automated sequential trace enrichment of dialysate and high-performance liquid chromatography

The use of the system, automated sequential trace enrichment of dialysates (ASTED), to prepare plasma and saliva prior to high pressure liquid chromatography of eletriptan (HPLC) is described. Chromatographic identification of one metabolite, UK-135,800 was also established. Using this technique the procedure was observed to be specific and linear over the range 0.50-250 ng/ml. The intra-batch imprecision (C.V.) of the method ranged from 0.56 to 5.70% at plasma eletriptan concentrations from 5.00 to 200 ng/ml, and the corresponding inter-batch imprecision ranged from 1.44 to 6.36%. At these plasma analyte concentrations, the overall inaccuracy (% bias) of the procedure ranged from -5.00 to 1.50%. Similar performances were observed for the estimation of eletriptan in saliva using near identical assay conditions. The application of the assay to a pharmacokinetic investigation during a clinical study is presented.

Stability of driving fear acquisition pathways over one year

The present study was conducted in response to increasing concerns about the potential unreliability of retrospective accounts in assessing the origins of fears and phobias. Some investigators [e.g. Menzies, R.G., & Clarke, J.C. (1993). The etiology of fear of heights and its relationship to severity and individual response patterns. Behaviour Research and Therapy, 31, 355-365; Kirkby, K.C., Menzies, R.G., Daniels, B.A., & Smith, K.L. (1995). Aetiology of spider phobia: Classificatory differences between two origins instruments. Behaviour Research and Therapy, 33, 955-958; King, N.J., Gullone, E., & Ollendick, T.H. (1998). Etiology of childhood phobias: current status of Rachman's three pathways theory. Behaviour Research and Therapy, 36, 297-309.] have questioned the reliability of retrospective reports at a single assessment point, although the test-retest reliability of such accounts has yet to be examined. The aim of the present study was to conduct a one-year follow-up of the subclinical driving-fearful sample studied by Taylor and Deane [Taylor, J. E., & Deane, F. P. (1999). Acquisition and severity of driving-related fears. Behaviour Research and Therapy, 37, 435-449.] to primarily investigate, the stability of fear onset ascriptions and fear severity over time. 85 respondents completed a questionnaire which assessed fear origins, anxiety response patterns, and additional fear-relevant events occurring over the year. The results suggest that retrospective accounts of fear onset may be quite unstable over time, although this instability does not clearly appear to be related to intervening events, and limitations of the study make these results inconclusive. Fear-relevant negative thinking worsened over time, while physiological reactions and general anxiety remained relatively stable. The theoretical, methodological and clinical implications of the findings are discussed, along with suggestions for future research.

Highly potent cyclic disulfide antagonists of somatostatin

The search for synthetic analogues of somatostatin (SRIF) which exhibit selective affinities for the five known receptor subtypes (sst1-5) has generated a large number of potent agonist analogues. Many of these agonists display good subtype selectivities and affinities for the subtypes 2, 3, and 5, with very few selective for sst1 or sst4. Until the recent report by Bass and co-workers (Mol. Pharmacol. 1996, 50, 709-715; erratum Mol. Pharmacol. 1997, 51, 170), no true antagonists of somatostatin had been discovered, let alone any displaying differential receptor subtype selectivity. In this present study, we further explore the effect of this putative L,5D6 antagonist motif on somatostatin octapeptide analogues with a cyclic hexapeptide core. The most potent antagonist found to date is H-Cpa-cyclo[DCys-Tyr-DTrp-Lys-Thr-Cys]-Nal-NH2, PRL-2970 (21), which has an IC50 of 1.1 nM in a rat pituitary growth hormone in vitro antagonist assay versus SRIF (1 nM). This analogue bound to cloned human somatostatin subtype 2 receptors with a Ki of 26 nM. The highest hsst2 affinity analogue was H-Cpa-cyclo[DCys-Pal-DTrp-Lys-Tle-Cys]-Nal-NH2, PRL-2915 (15), with a Ki of 12 nM (IC50 = 1.8 nM). This analogue was also selective for hsst2 over hsst3 and hsst5 by factors of 8 and 40, respectively, and had no agonist activity when tested alone at concentrations up to 10 microM. Regression analysis of the binding affinities versus the observed antagonist potencies revealed high correlations for hsst2 (r = 0.65) and hsst3 (r = 0.52) with a less significant correlation to hsst5 (r = 0.40). This is quite different from the somatostatin agonist analogues which show a highly significant correlation to hsst2 (r > 0.9). Receptor-selective somatostatin antagonists should provide valuable tools for characterizing the many important physiological functions of this neuropeptide.

First Report of Dothistroma septospora on Native Limber and Whitebark Pine in Montana

Dothistroma septospora (Doroguine) Morelet (= Dothistroma pini Hulbary), the anamorph of Mycosphaerella pini Rostr. in Munk, has been reported to cause needle blight in 29 Pinus species and hybrids in North America, including limber pine (P. flexilis James) in plantings in Kansas, Nebraska, and Ohio. We are unaware of any reports of D. septospora on limber or whitebark pine (P. albicaulis Engelm.) growing within their native ranges in the western United States. In June 1997, limber and whitebark pine in Montana were observed with severe defoliation and symptoms typical of those caused by D. septospora: affected second- and third-year needles were green at the base with brown tips or reddish-brown spots or bands, and black fruiting bodies in discolored portions of needles. Symptomatic needles were collected in natural stands of limber pine at 22 locations representing 15 counties in central, south-central, and southwestern Montana, and whitebark pine at three locations representing two counties in the Crazy Mountains in south-central Montana. Approximately 20 needles and five stromata from each location were examined with dissecting and compound microscopes to observe morphological features. Stromata were black, linear, 150 to 1450 μm (average 650 μm) by 65 to 450 μm (average 190 μm), subepidermal, and erumpent. Conidiophores were hyaline and unbranched. Conidia were 16.0 to 23.5 μm (average 18.5 μm) by 3.0 to 4.1 μm (average 3.4 μm), hyaline, 3 to 5 septate, blunt at the ends, and slightly falcate. The fungus described above was found at all sample locations. The teleomorph, M. pini, was not observed. Symptom expression and mycological characteristics were consistent with Hulbary's lectotype (1) of D. pini (= D. septospora). This is the first report of D. septospora on limber and whitebark pine within the hosts' native ranges. Reference: (1) R. L. Hulbary. Ill. Nat. Hist. Surv. Bull. 21:231, 1941.

Inhibition of human pancreatic islet insulin release by receptor-selective somatostatin analogs directed to somatostatin receptor subtype 5

Somatostatin (SS)-14 and SS28 are produced by pancreatic D cells and gut mucosa and inhibit pancreatic islet insulin and glucagon release. There are five distinct SS receptor (SSTR) subtypes, namely SSTR1-5, which show different affinities for SS14 and SS28. In order to identify the subtype responsible for inhibition of insulin release by human B cells, SSTR-selective SS analogs were tested in isolated human islets. Glucose-stimulated insulin secretion in human islets incubated for 1 hr at 20 mM glucose, and in islets cultured for 24 hr at a near-physiological (6.1 mM) glucose concentration, was inhibited (<50% of the control) by SSTR5-specific analogs and by SS14 and SS28. SS14, SS28, and different SSTR5 preferential analogs also inhibited islet amyloid polypeptide release during the 24-hr culture. On the other hand, a group of SSTR2-selective analogs failed to inhibit insulin release. Analysis by reverse transcription-polymerase chain reaction indicated that human islets express similar amounts of SSTR2 and SSTR5 mRNAs, while human pancreatic ductal cells express much lower levels of these mRNAs. In conclusion, our data suggest that SSTR5 is an important mediator of the insulin inhibitory action of SS in cultured human islets.

Acquisition and severity of driving-related fears

Rachman's theory of fear acquisition proposes that directly-conditioned fears will differ from indirectly-conditioned fears in magnitude and anxiety response patterns, however the theory has received inconsistent empirical support. The aim of the present study was to describe the fear acquisition pathways for a community sample who reported driving-related fears, and to test Rachman's theory of fear acquisition. One hundred and ninety participants completed a questionnaire which assessed a variety of driving-related situations, reactions to motor vehicle accidents (MVAs), and anxiety response patterns. Professional psychological helpseeking and perceived need for treatment for driving-related fears were also assessed. Results failed to support Rachman's predictions. However, it was confirmed that respondents who had been involved in an MVA were more likely to ascribe their fears to a directly-conditioned pathway. The theoretical and methodological implications of the findings are discussed, along with suggestions for assessment of those with driving-related fears.

Synthesis and binding properties of cyclohexapeptide somatostatin analogs containing naphthylalanine and arylalkyl peptoid residues

We report the synthesis, binding affinities to the recombinant human somatostatin receptors, and structure-activity relationship studies of compounds related to the cyclic hexapeptide, c-[Pro6-Phe7-D-Trp8Lys9-Thr10-Phe11], L-363,301 (the numbering in the sequence refers to the position of the residues in native somatostatin). The Pro residue in this compound is replaced with the arylalkyl peptoid residues Nphe (N-benzylglycine), (S)betaMeNphe [(S)-N-[alpha(-methyl)benzyl]glycine] or (R)betaMeNphe [(R)-N-[(alpha-methyl)benzyl]glycine] and L-1-naphthylalanine is incorporated into either position 7 or 11 of the parent compound. The synthesis and binding data of the Nnal6 ([N-naphthylmethyl]glycine) analog of L-363,301 is also reported. The incorporation of the Nnal residue into position 6 of L-363,301 resulted in an analog with weaker binding affinities to all hsst receptors but enhanced selectivity towards the hsst2 receptor compared with the parent compound. The other compounds bind effectively to the hsst2 receptor but show some variations in the binding to the hsst3 and hsst5 receptors resulting in different ratios of binding affinities to the hsst5 and hsst2 or hsst3 and hsst2, respectively. The incorporation of the Nphe residue into position 6 and the Nal residue into position 7 of L-363,301 led to a compound which binds potently to the hsst2 and has increased selectivity towards this receptor (weaker binding to hsst3 and hsst5 receptors) compared with the parent compound. The analogs with beta-methyl chiral substitutions in the aromatic peptoid side chain and Nal in position 7 or 11 bind effectively to the hsst2 and hsst5 receptors. They exhibit similar ratios of binding affinities to the hsst5 and hsst2 receptors as observed for L-363,301. There are however minor differences in binding to the hsst3 receptor among these analogs. These studies allow us to investigate the influence of additional hydrophobic groups on the binding activity to the isolated human somatostatin receptors and the results are important for the design of other somatostatin analogs.

Synthesis and binding potencies of cyclic hexapeptide analogs of somatostatin incorporating acidic and basic peptoid residues

The synthesis, binding affinity, and structure-activity relationships of compounds related to the cyclic hexapeptide, c[Pro6-Phe7-D-Trp8-Lys9-Thr10-Phe11], L-363,301 (the numbering in the sequence refers to the position of the residue in native somatostatin) is reported. The Pro residue in this compound is replaced with the peptoid residues Nasp [N-(2-carboxyethyl) glycine], Ndab [N-(2-aminoethyl) glycine] and Nlys [N-(4-aminobutyl) glycine]. This series of compounds enables us to draw conclusions about the influence of positively or negatively charged residues in the bridging region on the binding affinity towards the isolated human somatostatin receptors. A loss of binding to the recombinant human somatostatin (hsst) receptors in the Nasp analog compared with L-363,301 and compared with the Ndab and Nlys analogs clearly demonstrates that the presence of an acidic residue in the bridging region is unfavorable for binding to the hsst receptors. Comparison between the Ndab analog and the Nlys analog suggests that the presence of a basic residue in the bridging region might be advantageous for binding to the hsst5 receptor provided that the residue bearing the basic group extends far enough to allow for interaction with the receptor, while the length of the basic peptoid residue does not influence binding to the hsst2 receptor. These results are useful for the design of hsst5 selective somatostatin analogs.

Prenatal onset spinal muscular atrophy

Five patients with severe spinal muscular atrophy (SMA) type I, all of whom presented with reduced fetal movements in utero, severe weakness at birth, and short survival time were assessed to attempt to determine whether their phenotype could be explained by their genotype. The diagnosis was confirmed by clinical, electrophysiological and histopathological features. Polymerase chain reaction assays were used to define the molecular diagnosis. A gene-dosage assay was used to assess the quantity of centromeric survival motor neuron gene (SMNc) present. In all cases the telomeric survival motor neuron gene (SMNt) was absent. The SMNc gene was present but in reduced copy number compared with a control group of children with less severe type I SMA, so may be important in determining severity. In the differential diagnosis of reduced fetal movements, SMA should be considered. The clinical classification may in future be clarified by molecular genetic findings.

Establishing efficient partner notification periods for patients with chlamydia

OBJECTIVES

To delineate chlamydia partner notification periods with high proportions of infected, untreated sexual partners, and to evaluate relevant Centers for Disease Control (CDC) recommendations.

METHODS

Disease Intervention Specialists (DIS) offered contact tracing services to all chlamydia patients (N = 1,309) reported in Colorado Springs between July 1996 and June 1997. Patients were asked to identify sexual partners during the 180 days preceding treatment. Partners were actively sought by DIS and offered DNA amplification testing.

RESULTS

Of 1,309 patients, 1,109 were interviewed, resulting in 2,293 named partners. Two fifths of eligible partners were located; inability to examine partners was related to time of last exposure and to frequency of sexual exposure. Of located partners, 95% were tested with DNA amplification technology. Adherence to CDC criteria identified 88% of infected, untreated partners; the other 12% consisted mainly of epidemiologically important asymptomatic men whose infection is seldom identified by current public health interventions.

CONCLUSIONS

The chlamydia partner notification recommendations of the CDC are adequate, but miss men with long-standing infection. These men contribute to entrenched chlamydia endemicity; targeted programs to screen high-risk men merit serious consideration.