Reversed Holocene temperature-moisture relationship in the Horn of Africa

Anthropogenic climate change is predicted to severely impact the global hydrological cycle1, particularly in tropical regions where agriculture-based economies depend on monsoon rainfall2. In the Horn of Africa, more frequent drought conditions in recent decades3,4 contrast with climate models projecting precipitation to increase with rising temperature5. Here we use organic geochemical climate-proxy data from the sediment record of Lake Chala (Kenya and Tanzania) to probe the stability of the link between hydroclimate and temperature over approximately the past 75,000 years, hence encompassing a sufficiently wide range of temperatures to test the 'dry gets drier, wet gets wetter' paradigm6 of anthropogenic climate change in the time domain. We show that the positive relationship between effective moisture and temperature in easternmost Africa during the cooler last glacial period shifted to negative around the onset of the Holocene 11,700 years ago, when the atmospheric carbon dioxide concentration exceeded 250 parts per million and mean annual temperature approached modern-day values. Thus, at that time, the budget between monsoonal precipitation and continental evaporation7 crossed a tipping point such that the positive influence of temperature on evaporation became greater than its positive influence on precipitation. Our results imply that under continued anthropogenic warming, the Horn of Africa will probably experience further drying, and they highlight the need for improved simulation of both dynamic and thermodynamic processes in the tropical hydrological cycle.

The global coverage of prevalence data for mental disorders in children and adolescents

AIMS

Children and adolescents make up almost a quarter of the world's population with 85% living in low- and middle-income countries (LMICs). Globally, mental (and substance use) disorders are the leading cause of disability in young people; however, the representativeness or 'coverage' of the prevalence data is unknown. Coverage refers to the proportion of the target population (ages 5-17 years) represented by the available data.

METHODS

Prevalence data for conduct disorder (CD), attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), eating disorders (EDs), depression, and anxiety disorders were sourced from systematic reviews conducted for the Global Burden of Disease Study 2010 (GBD 2010) and 2013 (GBD 2013). For each study, the location proportion was multiplied by the age proportion to give study coverage. Location proportion was calculated by dividing the total study location population by the total study location population. Age proportion was calculated by dividing the population of the country aged within the age range of the study sample by the population of the country aged within the age range of the study sample. If a study only sampled one sex, study coverage was halved. Coverage across studies was then summed for each country to give coverage by country. This method was repeated at the region and global level, and separately for GBD 2013 and GBD 2010.

RESULTS

Mean global coverage of prevalence data for mental disorders in ages 5-17 years was 6.7% (CD: 5.0%, ADHD: 5.5%, ASDs: 16.1%, EDs: 4.4%, depression: 6.2%, anxiety: 3.2%). Of 187 countries, 124 had no data for any disorder. Many LMICs were poorly represented in the available prevalence data, for example, no region in sub-Saharan Africa had more than 2% coverage for any disorder. While coverage increased between GBD 2010 and GBD 2013, this differed greatly between disorders and few new countries provided data.

CONCLUSIONS

The global coverage of prevalence data for mental disorders in children and adolescents is limited. Practical methodology must be developed and epidemiological surveys funded to provide representative prevalence estimates so as to inform appropriate resource allocation and support policies that address mental health needs of children and adolescents.

Gender-related patterns and determinants of recent help-seeking for past-year affective, anxiety and substance use disorders: findings from a national epidemiological survey

AIMS

To examine: (1) gender-specific determinants of help-seeking for mental health, including health professional consultation and the use of non-clinical support services and self-management strategies (SS/SM) and; (2) gender differences among individuals with unmet perceived need for care.

METHOD

Analyses focused on 689 males and 1075 females aged 16-85 years who met ICD-10 criteria for a past-year affective, anxiety or substance use disorder in an Australian community-representative survey. Two classifications of help-seeking for mental health in the previous year were created: (1) no health professional consultation or SS/SM, or health professional consultation, or SS/SM only, and; (2) no general practitioner (GP) or mental health professional consultation, or GP only consultation, or mental health professional consultation. Between- and within-gender help-seeking patterns were explored using multinomial logistic regression models. Characteristics of males and females with unmet perceived need for care were compared using chi-square tests.

RESULTS

Males with mental or substance use disorders had relatively lower odds than females of any health professional consultation (adjusted odds ratio [AOR] = 0.46), use of SS/SM only (AOR = 0.59), and GP only consultation (AOR = 0.29). Notably, males with severe disorders had substantially lower odds than females of any health professional consultation (AOR = 0.29) and GP only consultation (AOR = 0.14). Most correlates of help-seeking were need-related. Many applied to both genders (e.g., severity, disability, psychiatric comorbidity), although some were male-specific (e.g., past-year reaction to a traumatic event) or female-specific (e.g., past-year affective disorder). Certain enabling and predisposing factors increased the probability of health professional consultation for both genders (age 30+ years) or for males (unmarried, single parenthood, reliance on government pension). Males with unmet perceived need for care were more likely to have experienced a substance use disorder and to want medicine or tablets or social intervention, whereas their females peers were more likely to have experienced an anxiety disorder and to want counselling or talking therapy. For both genders, attitudinal/knowledge barriers to receiving the types of help wanted (e.g., not knowing where to get help) were more commonly reported than structural barriers (e.g., cost).

CONCLUSIONS

Findings suggest a need to address barriers to help-seeking in males with severe disorders, and promote GP consultation. Exploring gender-specific attitudinal/knowledge barriers to receiving help, and the types of help wanted, may assist in designing interventions to increase consultation. Mental health promotion/education efforts could incorporate information about the content and benefits of evidence-based treatments and encourage males to participate in other potentially beneficial actions (e.g., physical activity).

Excess mortality from mental, neurological and substance use disorders in the Global Burden of Disease Study 2010

AIMS

Mortality-associated burden of disease estimates from the Global Burden of Disease 2010 (GBD 2010) may erroneously lead to the interpretation that premature death in people with mental, neurological and substance use disorders (MNSDs) is inconsequential when evidence shows that people with MNSDs experience a significant reduction in life expectancy. We explore differences between cause-specific and excess mortality of MNSDs estimated by GBD 2010.

METHODS

GBD 2010 cause-specific death estimates were produced using the International Classification of Diseases death-coding system. Excess mortality (all-cause) was estimated using natural history models. Additional mortality attributed to MNSDs as underlying causes but not captured through GBD 2010 methodology is quantified in the comparative risk assessments.

RESULTS

In GBD 2010, MNSDs were estimated to be directly responsible for 840 000 deaths compared with more than 13 million excess deaths using natural history models.

CONCLUSIONS

Numbers of excess deaths and attributable deaths clearly demonstrate the high degree of mortality associated with these disorders. There is substantial evidence pointing to potential causal pathways for this premature mortality with evidence-based interventions available to address this mortality. The life expectancy gap between persons with MNSDs and the general population is high and should be a focus for health systems reform.

The epidemiology and global burden of autism spectrum disorders

BACKGROUND

Autism spectrum disorders (ASDs) are persistent disabling neurodevelopmental disorders clinically evident from early childhood. For the first time, the burden of ASDs has been estimated for the Global Burden of Disease Study 2010 (GBD 2010). The aims of this study were to develop global and regional prevalence models and estimate the global burden of disease of ASDs.

METHOD

A systematic review was conducted for epidemiological data (prevalence, incidence, remission and mortality risk) of autistic disorder and other ASDs. Data were pooled using a Bayesian meta-regression approach while adjusting for between-study variance to derive prevalence models. Burden was calculated in terms of years lived with disability (YLDs) and disability-adjusted life-years (DALYs), which are reported here by world region for 1990 and 2010.

RESULTS

In 2010 there were an estimated 52 million cases of ASDs, equating to a prevalence of 7.6 per 1000 or one in 132 persons. After accounting for methodological variations, there was no clear evidence of a change in prevalence for autistic disorder or other ASDs between 1990 and 2010. Worldwide, there was little regional variation in the prevalence of ASDs. Globally, autistic disorders accounted for more than 58 DALYs per 100 000 population and other ASDs accounted for 53 DALYs per 100 000.

CONCLUSIONS

ASDs account for substantial health loss across the lifespan. Understanding the burden of ASDs is essential for effective policy making. An accurate epidemiological description of ASDs is needed to inform public health policy and to plan for education, housing and financial support services.

The global burden of anxiety disorders in 2010

BACKGROUND

Despite their high prevalence, the global burden of anxiety disorders has never been calculated comprehensively. The new Global Burden of Disease (GBD) study has estimated burden due to morbidity and mortality caused by any anxiety disorder.

METHOD

Prevalence was estimated using Bayesian meta-regression informed by data identified in a systematic review. Years of life lived with disability (YLDs) were calculated by multiplying prevalent cases by an average disability weight based on severity proportions (mild, moderate and severe). Disability-adjusted life years (DALYs) were then calculated and age standardized using global standard population figures. Estimates were also made for additional suicide mortality attributable to anxiety disorders. Findings are presented for YLDs, DALYs and attributable burden due to suicide for 21 world regions in 1990 and 2010.

RESULTS

Anxiety disorders were the sixth leading cause of disability, in terms of YLDs, in both high-income (HI) and low- and middle-income (LMI) countries. Globally, anxiety disorders accounted for 390 DALYs per 100,000 persons [95% uncertainty interval (UI) 191-371 DALYs per 100,000] in 2010, with no discernible change observed over time. Females accounted for about 65% of the DALYs caused by anxiety disorders, with the highest burden in both males and females experienced by those aged between 15 and 34 years. Although there was regional variation in prevalence, the overlap between uncertainty estimates means that substantive differences in burden between populations could not be identified.

CONCLUSIONS

Anxiety disorders are chronic, disabling conditions that are distributed across the globe. Future estimates of burden could be further improved by obtaining more representative data on severity state proportions.

Global prevalence of anxiety disorders: a systematic review and meta-regression

BACKGROUND

The literature describing the global prevalence of anxiety disorders is highly variable. A systematic review and meta-regression were undertaken to estimate the prevalence of anxiety disorders and to identify factors that may influence these estimates. The findings will inform the new Global Burden of Disease study. Method A systematic review identified prevalence studies of anxiety disorders published between 1980 and 2009. Electronic databases, reference lists, review articles and monographs were searched and experts then contacted to identify missing studies. Substantive and methodological factors associated with inter-study variability were identified through meta-regression analyses and the global prevalence of anxiety disorders was calculated adjusting for study methodology.

RESULTS

The prevalence of anxiety disorders was obtained from 87 studies across 44 countries. Estimates of current prevalence ranged between 0.9% and 28.3% and past-year prevalence between 2.4% and 29.8%. Substantive factors including gender, age, culture, conflict and economic status, and urbanicity accounted for the greatest proportion of variability. Methodological factors in the final multivariate model (prevalence period, number of disorders and diagnostic instrument) explained an additional 13% of variance between studies. The global current prevalence of anxiety disorders adjusted for methodological differences was 7.3% (4.8-10.9%) and ranged from 5.3% (3.5-8.1%) in African cultures to 10.4% (7.0-15.5%) in Euro/Anglo cultures.

CONCLUSIONS

Anxiety disorders are common and the substantive and methodological factors identified here explain much of the variability in prevalence estimates. Specific attention should be paid to cultural differences in responses to survey instruments for anxiety disorders.

Global variation in the prevalence and incidence of major depressive disorder: a systematic review of the epidemiological literature

BACKGROUND

Summarizing the epidemiology of major depressive disorder (MDD) at a global level is complicated by significant heterogeneity in the data. The aim of this study is to present a global summary of the prevalence and incidence of MDD, accounting for sources of bias, and dealing with heterogeneity. Findings are informing MDD burden quantification in the Global Burden of Disease (GBD) 2010 Study.

METHOD

A systematic review of prevalence and incidence of MDD was undertaken. Electronic databases Medline, PsycINFO and EMBASE were searched. Community-representative studies adhering to suitable diagnostic nomenclature were included. A meta-regression was conducted to explore sources of heterogeneity in prevalence and guide the stratification of data in a meta-analysis.

RESULTS

The literature search identified 116 prevalence and four incidence studies. Prevalence period, sex, year of study, depression subtype, survey instrument, age and region were significant determinants of prevalence, explaining 57.7% of the variability between studies. The global point prevalence of MDD, adjusting for methodological differences, was 4.7% (4.4-5.0%). The pooled annual incidence was 3.0% (2.4-3.8%), clearly at odds with the pooled prevalence estimates and the previously reported average duration of 30 weeks for an episode of MDD.

CONCLUSIONS

Our findings provide a comprehensive and up-to-date profile of the prevalence of MDD globally. Region and study methodology influenced the prevalence of MDD. This needs to be considered in the GBD 2010 study and in investigations into the ecological determinants of MDD. Good-quality estimates from low-/middle-income countries were sparse. More accurate data on incidence are also required.

Haemoperitoneum associated with ovulation in women with bleeding disorders: the case for conservative management and the role of the contraceptive pill

Haemoperitoneum secondary to ruptured corpus luteum is a rare complication for women on anticoagulants and with certain congenital bleeding disorders. A surgical approach is often taken, leading to oophorectomy in many cases. We describe three patients presenting with haemoperitoneum in association with factor VII deficiency, factor X deficiency and sitosterolaemia. In two of the patients, recurrent episodes occurred prior to introduction of the oral contraceptive pill. Conservative management with blood product and factor concentrate support was successful in avoiding surgery in three of the five episodes of bleeding. These cases demonstrate that preservation of ovarian function is possible with a conservative approach and recurrent episodes may be prevented by suppression of ovulation.

Beta blockers in older persons with heart failure: tolerability and impact on quality of life

OBJECTIVE

To determine tolerability and symptom changes associated with the introduction of bisoprolol treatment in older patients with heart failure.

DESIGN

Prospective observational cohort study.

SETTING

Geriatric medicine outpatient department of a university hospital.

PATIENTS

51 patients (mean age 78 years, range 70-89 years) with stable symptomatic heart failure caused by left ventricular systolic dysfunction.

INTERVENTIONS

Bisoprolol tablets, 1.25-10.0 mg.

MAIN OUTCOME MEASURES

Tolerability; changes in symptoms and exercise tolerance.

RESULTS

69% of patients tolerated bisoprolol. Mean tolerated dose was 7.6 mg. There was no change in symptoms or exercise capacity in those who tolerated bisoprolol. Perceived health status and symptoms of anxiety and depression improved during the titration period.

CONCLUSIONS

The rate of withdrawal from bisoprolol treatment in older patients with congestive heart failure was twice that previously reported in younger patients. The mean tolerated dose was similar to that found in trials reporting clinical efficacy. There was no evidence of a negative impact on symptoms or exercise capacity in patients who tolerated bisoprolol.

Diastolic heart failure in older people--myth or lost tribe?

Left ventricular diastolic dysfunction occurs due to a variable combination of abnormal myocardial relaxation and reduced ventricular compliance. The diagnosis of diastolic congestive heart failure is controversial. Some studies suggest that up to one-third of older people with symptomatic congestive heart failure (CHF) have echocardiograph evidence of diastolic dysfunction. Other authors have suggested the comorbid diseases often found in persons with suspected diastolic CHF explain the patient's symptoms and hence diastolic CHF is a misdiagnosis in many cases. Many of the characteristic echo features of diastolic dysfunction occur in normal ageing hearts. Unlike in systolic CHF, evidence for disease modifying treatment is lacking. Clinical trials currently in progress to determine the effectiveness of ACE inhibitors and angiotensin II receptor antagonists in the management of diastolic CHF may clarify the prognosis and management of this condition.

Synthesis and antiviral activity of prodrugs of the nucleoside 1-[2',3'-dideoxy-3'-C-(hydroxymethyl)-beta-D-erythropentofuranosyl] cytosine

The synthesis and antiviral evaluation of 21 prodrugs of 1-[2',3'-dideoxy-3'-C-(hydroxymethyl)-beta-D-erythropentofuranosyl ] cytosine 1 is reported. Cytosine N4-imine analogues were prepared by condensation of 1 with selected formamide dimethyl acetals. Amino acid substituted prodrugs were prepared from 1 or imine prodrug 2 by coupling with either N-tert-butoxycarbonyl (t-Boc)-L-valine or N-t-Boc-L- phenylalanine in the presence of dicyclohexycarbodiimide (DCC) and 4-dimethylaminopyridine (4-DMAP). Deprotection of the t-Boc protecting group was achieved with trifluoroacetic acid (TFAA) in methylene chloride. Cytosine N4-amide analogues were prepared by reaction of 1 with appropriate anhydrides in aqueous dioxane. Triacylated analogue 22 was prepared by reaction of 1 with four equivalents of benzoyl chloride in pyridine. Prodrugs were evaluated for activity against duck hepatitis B virus, herpes simplex virus types 1 and 2, human cytomegalovirus, and human immunodeficiency virus. A number of analogues were found comparable in activity to 1 with the cytosine N4-imine series more active than the amino acid substituted and cytosine N4-amide prodrugs. Slight to moderate cellular toxicity was observed with some analogues.

Peptidomimetic aminomethylene ketone inhibitors of interleukin-1 beta-converting enzyme (ICE)

Pyridone-based peptidomimetic inhibitors of recombinant human Interleukin-1 beta-converting enzyme (ICE, caspase-1) with an aminomethylene ketone activating group in the P1' position are described. Several analogues with sub-nanomolar Ki's versus ICE and improved aqueous solubility are reported.

A single sequence change destabilizes the influenza virus neuraminidase tetramer

A single change (E119G) in the influenza A virus N9 neuraminidase (NA) results in resistance of the enzyme to the NA inhibitor 4-Guanidino-Neu5Ac2en (4-GuDANA). This change causes a salt link between Glu119, which sits in a pocket in the bottom of the active site of the enzyme, and the 4-guanidinium moiety of the inhibitor to be lost. NA "heads" of the resistant enzyme produced only a few small crystals under conditions in which the wild-type enzyme readily formed large crystals. These small crystals were of sufficient quality to yield X-ray crystallographic data which confirmed the E119G change and demonstrated the presence of electron density representing either a strong structural-water molecule or an anionic species in place of the glutamate carboxylate. NA heads of the resistant enzyme also have greatly reduced NA activity per milligram of total protein. We have now found that the mutant NA heads consist predominantly of monomers with a few dimers and tetramers, as determined by electron microscopic analysis of the protein. The low level of enzymatic activity as well as the small number of crystals obtained were probably from the few tetramers remaining intact in the preparation. The purified wild-type and 4-GuDANA-resistant enzymes were treated with the homobifunctional NHS-ester cross linker, DTSSP. SDS-PAGE analysis of the treated enzymes clearly revealed cross-linked dimers of the wild-type enzyme. In contrast, only a small proportion of the 4-GuDANA-resistant neuraminidase was cross-linked. An examination of the known X-ray crystallographic structure of the wild-type NA reveals a salt bridge between Glu119 and Arg156 of the same monomer. Arg156 is a conserved amino acid that is situated at the interface between monomers, and a salt link between this amino acid and Glu119 may contribute to the stability of enzyme tetramers. It is suggested that the E119G alteration in the 4-GuDANA-resistant NA leads to the abrogation of this interaction and thus to the instability of the NA tetramers.

Differential effects of the incorporation of 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodouracil (FIAU) on the binding of the transcription factors, AP-1 and TFIID, to their cognate target DNA sequences

The thymidine analog, 1-(2-deoxy-2-fluoro-beta-D-arabino-furanosyl)-5-iodouracil (FIAU), is incorporated into DNA in cell culture and in vivo. To investigate the effect of incorporation of FIAU into DNA on the binding of transcription factors, oligonucleotide duplexes which bind specifically to activator protein 1 (AP-1) or to TFIID were synthesized and binding of these oligonucleotides to their respective proteins was studied using gel-shift analysis. When thymidine at position -3, -1, 1 or 7 (relative to the first thymidine of the core binding sequence) was replaced with FIAU, binding to AP-1 was approximately 82, 28, 86 and 51%, respectively, of the binding to the non-substituted oligonucleotide to AP-1. When thymidine at position 3 or 5 (each adjacent to the center of dyad symmetry) was replaced with FIAU, binding to AP-1 was abrogated. Oligonucleotides containing FIAU at positions -1, 3 or 5, were much less able to compete with radiolabeled wild-type oligonucleotides for binding to AP-1. In contrast, the presence of FIAU, depending on its location, resulted in the increased binding of TFIID to its consensus target DNA sequence. These results indicate that incorporation of FIAU into DNA may induce local conformational changes resulting in the altered ability of transcriptional factors to bind to their cognate DNA sequences. Additional studies demonstrated that the presence of FIAU at a position 5' to the cleavage site in the consensus sequence T*TAA (where * is the cleavage site) inhibited restriction of the oligomeric duplex by MseI.

Potent human immunodeficiency virus type 1 protease inhibitors that utilize noncoded D-amino acids as P2/P3 ligands

Noncoded D-amino acids have been designed to replace the quinaldic amide-asparaginyl moiety (P2/P3 ligand) found in several potent human immunodeficiency virus (HIV) protease inhibitors such as LY289612. The substituted nitrogen, optimally an N-methanesulfonyl moiety, served as a CH2CONH2 (asparagine side chain mimic), while the amino acid side chain became the backbone and P3 ligand of these novel inhibitors. Compounds derived from S-aryl-D-cysteine proved to be potent HIV protease inhibitors which also exhibited potent whole cell antiviral activity. Oxidation of the cysteines to the sulfoxide or sulfone oxidation states resulted in significant improvements in potency. For example, the compound derived from N-(methyl-sulfonyl)-2-S-naphthylcysteine sulfone, 17c, was a 3.5 nM inhibitor of HIV protease which inhibited the spread of virus in MT4 cells with an IC50 = 4.3 nM. Compounds 17c,g,i were found to be orally bioavailable in a rat model.

Molecular basis for the resistance of influenza viruses to 4-guanidino-Neu5Ac2en

We report the selection and characterization of influenza A/NWS-G70c and B/HK/8/73 (HG) viruses which are resistant to the potent influenza neuraminidase inhibitor, 4-guanidino-Neu5Ac2en. Viruses were selected which replicated in MDCK cells in the presence of 20 micrograms/ml inhibitor. The neuraminidase of resistant viruses was > 200-fold more resistant to 4-guanidino-Neu5Ac2en than was the neuraminidase of the parent viruses. Although amounts of neuraminidase protein were similar in resistant and parent viruses, the enzyme activity of the resistant neuraminidase heads was reduced by > 95% for the substrates used. Relative to parent viruses, the resistant viruses replicated to equal or greater titers in tissue culture and in embryonated chicken eggs. Sequence analysis revealed a single nucleotide mutation in the neuraminidase gene of each virus resulting in the change of the conserved Glu 119 (which lies in a pocket beneath the active site of the enzyme) to Gly thus eliminating an electrostatic interaction with the C-4 guanidinium moiety of the inhibitor. Mutations (Asn-->Ser) at amino acids 145 and 150 were also found in the hemagglutinin gene of the B/HK/8/73 (HG) virus resistant to 4-guanidino-Neu5Ac2en. No changes were found in the hemagglutinin gene of the resistant A/NWS-G70c virus.

Mechanisms of resistance to Onchocerca infection in blackflies

In this article Peter Ham, Hans Hagen, Andrea Baxter and Jorg Grunewald focus on the susceptibility of blackflies to parasitic filarial infection (particularly Onchocera spp, most of the vectors of which belong to the genus Simulium). They outline what is known about, as well as speculating on, the various defence mechanisms of these insects. Investigations have involved the use of natural and surrogate vectors of bovine onchocerciasis as models for the human vector-parasite relationship.

Approaches to vector control: new and trusted. 1. Humoral immune responses in blackfly and mosquito vectors of filariae

The vectors of filariasis, mosquitoes and blackflies, are capable of mounting a defence response to the infection. This selective review describes the molecules that are involved in these immune systems. Several antibacterial peptides are known to be induced and secreted into the haemolymph by the fat body and the circulating haemocytes. In addition, haemagglutinating lectins with carbohydrate specificities to the surface of the developing filarial larvae appear. Activation of a range of proteases occurs rapidly as does activation of the prophenoloxidase pathway. The possible roles of these and other molecules is discussed, together with mention of a working hypothesis as to how these molecules may be regulated.

Discovery and synthesis of methyl 2,5-dimethyl-4-[2- (phenylmethyl)benzoyl]-1H-pyrrole-3-carboxylate (FPL 64176) and analogues: the first examples of a new class of calcium channel activator

Methyl 2,5-dimethyl-4-[2-(phenylmethyl)benzoyl]-1H-pyrrole-3-carboxylate, FPL 64176 (1), is the first example of a new class of calcium channel activator (CCA) that does not act on any of the well-defined calcium channel modulator receptor sites, as typified by verapamil, diltiazem, and the dihydropyridines. The potent activity of 1, having the 2-(phenylmethyl)benzoyl substituent, was predicted using QSAR on an initial set of less potent benzoylpyrroles. When compared to the CCA Bay K 8644, 1 has similar potency on calcium uptake into GH3 cells (both have EC50 approximately 0.015 microM) but is appreciably more potent functionally at increasing contractility in a guinea pig atria preparation (1 has EC50 = 0.049 microM vs Bay K 8644 EC50 = 1.95 microM). 1 is an achiral, pharmacologically clean agonist with no demonstrable partial agonist properties and possesses appreciably higher efficacy than Bay K 8644. It should therefore become a useful biochemical and pharmacological tool for the study of calcium channels in many cell types.

Effect of bile acid on anorectal function in man

The effects of rectal infusions (500 ml) of deoxycholic acid (1 mmol/l, 3 mmol/l) or normal saline on basal anorectal motility and responses to rectal distension were studied in 11 normal volunteers. Deoxycholic acid (1 mmol/l) did not alter anorectal motor patterns under basal conditions but reduced the rectal volumes required to induce a desire to defecate (deoxycholic acid 76 (12) ml v saline 123 (12) ml; mean (SEM) p less than 0.01), and to produce anal relaxation (deoxycholic acid 83 (14) ml v saline 152 (24) ml; p less than 0.05) and perception of the rectal balloon (deoxycholic acid 56 (10) ml v saline 104 (17) ml; p less than 0.01) that were sustained for the period of distension (1 min). Seven of 10 subjects could not tolerate an infusion of 3 mmol/l deoxycholic acid. Between two and 30 minutes after the start of the infusion they experienced an extreme urge to defecate which was associated with large amplitude pressure waves in the rectal channels (amplitude 30 (5) mmHg, duration 0.7 (0.1) min, frequency 1.7 (0.4)/min). Such contractions were never seen during saline infusion. Thus, rectal infusion of deoxycholic acid at physiological concentrations increases the sensitivity of the rectum to distension, and promotes an urgent desire to defecate in normal subjects.

Evaluation of applied potential tomography as a new non-invasive gastric secretion test

Applied potential tomography (APT) is a new, non-invasive technique that can yield sequential images of changes in the resistivity of gastric contents. Studies were performed to investigate the application of APT to measure gastric acid secretion. Experiments in 20 normal volunteers showed that changes in gastric resistivity were closely correlated with changes in the volume (r = 0.80), the acidity (r = 0.83) and the total conductivity of gastric contents (r = 0.87). Studies in 13 patients referred for a pentagastrin test showed that changes in gastric resistivity before pentagastrin were closely correlated with basal acid output measured on a separate occasion (r = 0.85, p less than 0.001), while changes in gastric resistivity after pentagastrin were correlated with maximal acid output (r = 0.58, p less than 0.05). Ingestion of alcohol by six normal subjects decreased gastric resistivity markedly, probably due to alcohol induced gastric acid secretion as it was prevented by cimetidine. Applied potential tomography is a safe non-invasive method of measuring gastric acid secretion. The equipment is simple to use, and the test is comfortable and acceptable to patients.

The effect of two alpha 2-adrenoreceptor agonists and an antagonist on gastric emptying and mouth to caecum transit time in humans

Experiments were performed to investigate the effect of two alpha 2-adrenoreceptor agonists, clonidine and lidamidine, and a specific alpha 2-adrenoreceptor antagonist, idazoxan, on gastric emptying and mouth to caecum transit time (MCTT) of a radiolabelled meal in 27 healthy male subjects. Lidamidine (20 mg p.o.) and clonidine (0.3 mg p.o.), given alone had no significant effect on gastric emptying or MCTT suggesting that the anti-diarrhoeal action of clonidine and lidamidine are unlikely to be explained by a slowing of small intestinal transit. Idazoxan (20 mg p.o.) reversed the effect of clonidine in 10 subjects, who showed a delay in MCTT after taking clonidine, but did not alter MCTT under basal conditions. These results suggest that although the sympathetic nervous system can influence upper gastrointestinal motility by an action on alpha 2-adrenoreceptors, this action does not exert a tonic influence on upper gastrointestinal motility under basal conditions.

Applied potential tomography: a new non-invasive technique for assessing gastric function

Applied potential tomography is a new, non-invasive technique that yields sequential images of the resistivity of gastric contents after subjects have ingested a liquid or semi-solid meal. This study validates the technique as a means of measuring gastric emptying. Experiments in vitro showed an excellent correlation between measurements of resistivity and either the square of the radius of a glass rod or the volume of water in a spherical balloon when both were placed in an oval tank containing saline. Altering the lateral position of the rod in the tank did not alter the values obtained. Images of abdominal resistivity were also directly correlated with the volume of air in a gastric balloon. Profiles of gastric emptying of liquid meals obtained using APT were very similar to those obtained using scintigraphy or dye dilution techniques provided that acid secretion was inhibited by cimetidine. Profiles of emptying of a mashed potato meal using APT were also very similar to those obtained by scintigraphy. Measurements of the emptying of a liquid meal from the stomach were reproducible if acid secretion was inhibited by cimetidine. Thus, APT is an accurate and reproducible method of measuring gastric emptying of liquids and particulate food. It is inexpensive, well tolerated, easy to use and ideally suited for multiple studies in patients, even those who are pregnant. A preliminary study is also presented that assesses the technique as a means of measuring gastric acid secretion. Comparison of resistivity changes with measured acid secretion following the injection of pentagastrin shows good correlations. APT might offer a non-invasive alternative to the use of a nasogastric tube and acid collection.

Effect of naloxone, domperidone and idazoxan on the delay in gastric emptying induced by ileal lipid

Studies were carried out on 22 healthy male volunteers to investigate whether intravenous administration of either the opiate antagonist, naloxone, or the dopamine antagonist, domperidone, or the alpha 2-adrenoreceptor antagonist, idazoxan, could reverse the delay in gastric emptying induced by ileal infusion of lipid emulsion. Ileal infusion of 50% lipid emulsion significantly delayed the rate of gastric emptying compared with ileal infusion of isotonic saline (P less than 0.01). Intravenous infusion of naloxone (20 micrograms kg-1 hour-1) or prior administration of either intravenous domperidone (20 mg) or idazoxan (0.2 mg kg-1) did not inhibit the delay in gastric emptying induced by ileal infusion of lipid emulsion. These observations indicate that feedback regulation of gastric emptying by ileal lipid does not appear to be mediated by either dopaminergic or enkephalinergic neurons, nor by alpha 2-adrenoreceptors.

Swallowing food without chewing; a simple way to reduce postprandial glycaemia

1. The degree to which disruption by mastication affects the glycaemic response to four different carbohydrate foods was investigated in healthy human volunteers; each food was eaten by six subjects. 2. Subjects ate meals of sweetcorn, white rice, diced apple or potato on two occasions; on one occasion they chewed the food thoroughly, on the other occasion they swallowed each mouthful without chewing it. 3. When the foods were chewed the postprandial blood glucose levels rose to levels which varied according to the food ingested. 4. Swallowing without chewing reduced the glycaemic response to each food, achieving a similar effect as administration of viscous polysaccharides or 'slow-release' carbohydrates.