Linking ATP and allosteric sites to achieve superadditive binding with bivalent EGFR kinase inhibitors

Bivalent molecules consisting of groups connected through bridging linkers often exhibit strong target binding and unique biological effects. However, developing bivalent inhibitors with the desired activity is challenging due to the dual motif architecture of these molecules and the variability that can be introduced through differing linker structures and geometries. We report a set of alternatively linked bivalent EGFR inhibitors that simultaneously occupy the ATP substrate and allosteric pockets. Crystal structures show that initial and redesigned linkers bridging a trisubstituted imidazole ATP-site inhibitor and dibenzodiazepinone allosteric-site inhibitor proved successful in spanning these sites. The reengineered linker yielded a compound that exhibited significantly higher potency (~60 pM) against the drug-resistant EGFR L858R/T790M and L858R/T790M/C797S, which was superadditive as compared with the parent molecules. The enhanced potency is attributed to factors stemming from the linker connection to the allosteric-site group and informs strategies to engineer linkers in bivalent agent design.

Abstract 1426: Sox-based sensor phosphopeptides for continuous, homogeneous and quantitative monitoring of protein phosphatase activity

Introduction: The aberrant activation of oncogenic signaling pathways can drive tumorigenesis and malignant transformation, where deregulation of the activity of protein kinases or phosphatases can play a critical role. Several protein tyrosine phosphatases (PTPs) that are overexpressed in human cancers have recently been shown to activate signaling pathways and promote tumor development and progression (Sivaganesh et al., 2021. Protein Tyrosine Phosphatases: Mechanisms in Cancer. Int J Mol Sci. 22(23):12865). This reinforces the need for protein phosphatase inhibitors for cancer therapy, which requires robust assays to monitor PTP activity.

Experimental Procedures: We harnessed chelation-enhanced fluorescence by combining next generation sulfonamido-oxine (Sox) chromophore technology with high-throughput solid-phase peptide synthesis methods to identify optimized sequences based on known physiological substrates. PTP enzyme activity was monitored using the PhosphoSens® platform in kinetic mode (a progress curve in every well) using fluorescence intensity (Ex/Em 360/485 nm) or in endpoint mode with Europium and time-resolved fluorescence (Ex/Em 360/620 nm).

Results: Using commercially available phosphatases, we demonstrated the ability to rapidly identify novel Sox-based phosphopeptide substrates for each phosphatase. Performance measures included initial reaction rates, Km's, signal/background, linear reaction kinetics, absence of initial lags, assay sensitivity and specificity. Final optimized assay conditions were established for 28 different phosphatases. Each phosphatase was titrated to determine the lowest optimal assay concentration, demonstrating linearity and detection of low nM enzyme. Potency assessments using a set of compounds revealed sub nM inhibitor IC50 values and this included using sodium orthovanadate as a positive control. Finally, we demonstrated the ability to profile a range of novel phosphatase inhibitors to determine selectivity.

Conclusions: The generation of robust activity-based Sox-sensor phosphopeptide substrates opens new areas for effective drug discovery with protein phosphatases as an emerging target class. The PhosphoSens-Kinetic assay format is ideal for assessing enzyme regulation and elucidating drug mechanism of action, potency, and profiling. The PhosphoSens-Red endpoint format is ideal for HTS and high-throughput SAR. Together, these formats can be applied across the entire target discovery and drug development workflow, providing a dramatic improvement in performance and productivity needed to address the challenges and opportunities of next generation protein kinase and phosphatase inhibitors.

Citation Format: Susan Cornell-Kennon, Erik Schaefer, Earl May, Matthew Hakar. Sox-based sensor phosphopeptides for continuous, homogeneous and quantitative monitoring of protein phosphatase activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1426.

Abstract 2766: Automation of linear range determination: Enzymatic progress curve applications

To characterize modulators of enzymatic activity, a continuous assay format will quantify with confidence the initial reaction velocity far better than an end point assay. When the progress curve is linear from the start and remains linear throughout the experiment, a single end point reading can approximate the reaction rate, but a kinetic assay will provide the rate more accurately. However, if there is a delay in the onset of the reaction, or there are other changes in reaction rate over time, then a single end point reading is insufficient. Thus, important information about the reaction can be missed or mischaracterized. While visual inspection is the most common way to determine the range of the progress curve from which to extract rate information, this method is not practical when thousands of progress curves are generated in an experimental day. We have developed an automated protocol to streamline and optimize the process. The heuristic algorithm analyzes the progress curve to identify different regions for characterization (e.g. lag, primary rate, secondary rate, final plateau) and then extract rates of interest for each of these regions. These rates are subsequently used to measure the specific activity of the enzyme under various assay conditions, and to characterize the modulation of that activity: simple dose-response testing, mode of inhibition analysis, time-dependent inhibition determination, reversibility testing, determination of residence time for reversible inhibitors, and kinact/KI analysis for irreversible inhibitors. We describe the algorithm and several applications as they apply to protein kinases using the PhosphoSens assay platform from AssayQuant within the Analyze module of the Scigilian data analysis package.

Citation Format: Earl William May, Daniel Urul, Susan Cornell-Kennon, Zhibing Lu, Erik Schaefer, Sam Hoare, France Laliberté, Quay Vong, Paul Payette, Jean Marois. Automation of linear range determination: Enzymatic progress curve applications [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2766.

Wiedemann-Steiner syndrome as a major cause of syndromic intellectual disability: A study of 33 French cases

Wiedemann-Steiner syndrome (WSS) is a rare syndromic condition in which intellectual disability (ID) is associated with hypertrichosis cubiti, short stature, and characteristic facies. Following the identification of the causative gene (KMT2A) in 2012, only 31 cases of WSS have been described precisely in the literature. We report on 33 French individuals with a KMT2A mutation confirmed by targeted gene sequencing, high-throughput sequencing or exome sequencing. Patients' molecular and clinical features were recorded and compared with the literature data. On the molecular level, we found 29 novel mutations. We observed autosomal dominant transmission of WSS in 3 families and mosaicism in one family. Clinically, we observed a broad phenotypic spectrum with regard to ID (mild to severe), the facies (typical or not of WSS) and associated malformations (bone, cerebral, renal, cardiac and ophthalmological anomalies). Hypertrichosis cubiti that was supposed to be pathognomonic in the literature was found only in 61% of our cases. This is the largest series of WSS cases yet described to date. A majority of patients exhibited suggestive features, but others were less characteristic, only identified by molecular diagnosis. The prevalence of WSS was higher than expected in patients with ID, suggesting than KMT2A is a major gene in ID.

Molecular, clinical and neuropsychological study in 31 patients with Kabuki syndrome and KMT2D mutations

Kabuki syndrome (KS-OMIM 147920) is a rare developmental disease characterized by the association of multiple congenital anomalies and intellectual disability. This study aimed to investigate intellectual performance in children with KS and link the performance to several clinical features and molecular data. We recruited 31 children with KMT2D mutations who were 6 to 16 years old. They all completed the Weschler Intelligence Scale for Children, fourth edition. We calculated all indexes: the Full Scale Intellectual Quotient (FSIQ), Verbal Comprehension Index (VCI), Perceptive Reasoning Index (PRI), Processing Speed Index (PSI), and Working Memory Index (WMI). In addition, molecular data and several clinical symptoms were studied. FSIQ and VCI scores were 10 points lower for patients with a truncating mutation than other types of mutations. In addition, scores for FSIQ, VCI and PRI were lower for children with visual impairment than normal vision. We also identified a discrepancy in indexes characterized by high WMI and VCI and low PRI and PSI. We emphasize the importance of early identification and intensive care of visual disorders in patients with KS and recommend individual assessment of intellectual profile.

An algebraic model to determine substrate kinetic parameters by global nonlinear fit of progress curves

We propose that the time course of an enzyme reaction following the Michaelis-Menten reaction mechanism can be conveniently described by a newly derived algebraic equation, which includes the Lambert Omega function. Following Northrop's ideas [Anal. Biochem.321, 457-461, 1983], the integrated rate equation contains the Michaelis constant (K_M) and the specificity number (k_S≡k_cat/K_M) as adjustable parameters, but not the turnover number k_cat. A modification of the usual global-fit approach involves a combinatorial treatment of nominal substrate concentrations being treated as fixed or alternately optimized model parameters. The newly proposed method is compared with the standard approach based on the "initial linear region" of the reaction progress curves, followed by nonlinear fit of initial rates to the hyperbolic Michaelis-Menten equation. A representative set of three chelation-enhanced fluorescence EGFR kinase substrates is used for experimental illustration. In one case, both data analysis methods (linear and nonlinear) produced identical results. However, in another test case, the standard method incorrectly reported a finite (50-70 μM) K_M value, whereas the more rigorous global nonlinear fit shows that the K_M is immeasurably high.

Genetic counselling difficulties and ethical implications of incidental findings from array-CGH: a 7-year national survey

Microarray-based comparative genomic hybridization (aCGH) is commonly used in diagnosing patients with intellectual disability (ID) with or without congenital malformation. Because aCGH interrogates with the whole genome, there is a risk of being confronted with incidental findings (IF). In order to anticipate the ethical issues of IF with the generalization of new genome-wide analysis technologies, we questioned French clinicians and cytogeneticists about the situations they have faced regarding IF from aCGH. Sixty-five IF were reported. Forty corresponded to autosomal dominant diseases with incomplete penetrance, 7 to autosomal dominant diseases with complete penetrance, 14 to X-linked diseases, and 4 were heterozygotes for autosomal recessive diseases with a high prevalence of heterozygotes in the population. Therapeutic/preventive measures or genetic counselling could be argued for all cases except four. These four IF were intentionally not returned to the patients. Clinicians reported difficulties in returning the results in 29% of the cases, mainly when the question of IF had not been anticipated. Indeed, at the time of the investigation, only 48% of the clinicians used consents mentioning the risk of IF. With the emergence of new technologies, there is a need to report such national experiences; they show the importance of pre-test information on IF.

[Workplace Health Promotion in Small, Medium-Sized and Large Enterprises of the Health-Care Sector - Frequency, Reasons for the Company Management to Take Action and Barriers to Implementation]

PURPOSE

The aim of this study was to gain insight into worksite health promotion in small and medium-sized companies compared to large concerns in Middle Franconia. Action in worksite health promotion, obstacles and demand for networks for workplace health promotion were determined.

METHOD

A standardised telephone interview served for collecting data for this cross-sectional study. The interviewee was always the manager or their proxy. 106 companies were contacted. The results of this study were analysed via qualitative and quantitative methods in SPSS(®) 20.

RESULTS

It was possible to reach and interview 80 companies, a return rate of 75.5%. More than half the companies (68.8%) implemented at least one activity for worksite health promotion, especially ergonomic measures and measures to promote physical activity. Taking the size of the company into consideration when analysing the results, previous study results are confirmed. With an increasing size of the company, the relative frequency of measures for workplace health promotion rises. The motivation for worksite health promotion ranges from keeping the employees healthy (38.2%) to worksite health promotion as part of the business culture (9.1%). 81.1% of the companies consider their activity in worksite health promotion to be successful. Furthermore, 80.0% of the firms that implemented worksite health promotion were supported by a partner like a health insurance (43.2%). Those companies that did not implement any activities for worksite health promotion, state as a prime reason that they did not think about it as yet (44.0%). Besides, 44.0% of the companies without any worksite health promotion would like to implement measures. 65.5% of the companies that already took action in worksite health promotion and 56.0% of the companies that did not would like to cooperate with other firms in a network for workplace health promotion. Mutual exchange is the most important factor for them.

CONCLUSION

The results of this study show that almost half of the companies that did not implement measures for worksite health promotion as yet would like to take action in this regard. For a bigger establishment of worksite health promotion, networks are predestinated and are best accompanied and supported by external professionals like health insurances, mutual indemnity associations or universities.

Mesoaxial polydactyly is a major feature in Bardet-Biedl syndrome patients with LZTFL1 (BBS17) mutations

Ciliopathies are heterogeneous disorders sharing different clinical signs due to a defect at the level of the primary cilia/centrosome complex. Postaxial polydactyly is frequently reported in ciliopathies, especially in Bardet-Biedl syndrome (BBS). Clinical features and genetic results observed in a pair of dizygotic twins with BBS are reported. The following manifestations were present: retinitis pigmentosa, bilateral insertional polydactyly, cognitive impairment and renal dysfunction. X-rays of the hands confirmed the presence of a 4th mesoaxial extra-digit with Y-shaped metacarpal bones. The sequencing of LZTFL1 identified a missense mutation (NM_020347.2: p.Leu87Pro; c.260T>C) and a nonsense mutation (p.Glu260*; c.778G>T), establishing a compound heterozygous status for the twins. A major decrease of LZTFL1 transcript and protein was observed in the patient's fibroblasts. This is the second report of LZTFL1 mutations in BBS patients confirming LZTFL1 as a BBS gene. Interestingly, the only two families reported in literature thus far with LZTFL1 mutations have in common mesoaxial polydactyly, a very uncommon feature for BBS. This special subtype of polydactyly in BBS patients is easily identified on clinical examination and prompts for priority sequencing of LZTFL1 (BBS17).

Mutations in SDCCAG8/NPHP10 Cause Bardet-Biedl Syndrome and Are Associated with Penetrant Renal Disease and Absent Polydactyly

The ciliopathies are an expanding group of disorders caused by mutations in genes implicated in the biogenesis and function of primary cilia. Bardet-Biedl syndrome (BBS) is a model ciliopathy characterized by progressive retinal degeneration, obesity, polydactyly, cognitive impairment, kidney anomalies and hypogonadism. Mutations in SDCCAG8(NPHP10) were described recently in patients with nephronophthisis and retinal degeneration (Senior-Loken syndrome; SLS). Given the phenotypic and genetic overlap between known ciliopathy genes, we hypothesized that mutations in SDCCAG8 might also contribute alleles to more severe, multisystemic ciliopathies. We performed genetic and phenotypic analyses of 2 independent BBS cohorts. Subsequent to mutation screening, we made a detailed phenotypic analysis of 5 families mutated for SDCCAG8 (3 homozygous and 2 compound heterozygous mutations) and conducted statistical analyses across both cohorts to examine possible phenotype-genotype correlations with mutations at this locus. All patients with mutations in SDCCAG8 fulfilled the diagnostic criteria for BBS (retinal degeneration, obesity, cognitive defects, renal failure, hypogonadism). Interestingly, none of the patients with primary SDCCAG8 mutations had polydactyly, a frequent but not obligatory BBS feature. In contrast, the same patients displayed early-onset renal failure, obesity, as well as recurrent pulmonary and ENT infections. Comparison of the phenotypes of these families with our entire BBS cohort indicated that renal impairment and absent polydactyly correlated significantly with causal SDCCAG8 mutations. Thus, SDCCAG8 mutations are sufficient to cause BBS in 1-2% of our combined cohorts, and define this gene as the sixteenth BBS locus (BBS16). The absence of polydactyly and the concomitant, apparently fully penetrant association with early kidney failure represents the first significant genotype-phenotype correlation in BBS that potentially represents an indicator for phenotype-driven priority screening and informs specific patient management.

Confirmation of the role of diabetes in the local recurrence of surgically resected non-small cell lung cancer

PURPOSE

We recently demonstrated that diabetes mellitus was an independent risk factor for local recurrence (LR) for patients undergoing resection of non-small cell lung cancer (NSCLC). This investigation was performed to confirm or refute this finding in a different patient cohort.

MATERIALS AND METHODS

Patients were eligible if they did not have a second primary cancer within 5 years of the original diagnosis, had at least 3-month follow-up, and did not receive radiotherapy. There were 373 and 168 patients in the original (P1) and confirmatory (P2) cohorts, respectively, with 66 and 30 patients with diabetes.

RESULTS

The median follow-up was 33 months (range, 3-98 months). Diabetes was an independent risk factor for LR in a Cox model in both the P2 (p=0.05, hazard ratio [HR] 2.15) and P1 (p=0.008, HR 1.90) cohorts, separately from BMI, glucose control, and the presence of the metabolic syndrome. The rates of LR in the patients with diabetes after combining the cohorts at 2, 3, and 5 years were 23%, 33%, and 56%, respectively; these rates were 15%, 19%, and 26% in non-diabetics. In multivariate Cox regression and competing risk analysis of the combined cohorts, the HRs for LR in patients with diabetes exceeded those of more established risk factors for LR including a 1-cm increase in tumor size and lymphovascular invasion.

CONCLUSIONS

Diabetes was confirmed to be an independent predictor of the risk of LR following resection of NSCLC.

Development and improvement of a serum-free suspension process for the production of recombinant adenoviral vectors using HEK293 cells

Human Embryonic Kidney 293 (HEK293) cells were adapted into a serum-free suspension medium through steps of gradual serum weaning for the production of adenoviral (AdV) gene therapy vectors. The presence of sodium heparin in the medium formulation reduced cell clumping dramatically in suspension culture. The adapted cells were ready to grow either in serum-containing medium as an attached culture or in serum-free medium in suspension culture. A scalable production process was developed in shake flasks and was then evaluated in stirred tank bioreactors. This process includes a growth phase in batch-mode followed by a production phase involving medium perfusion and supplementation. Fortification with calcium chloride post viral inoculation resulted in an increase in virus production by at least one fold. Addition of stimulating agents such as sodium butyrate, N-acetyl-L-cysteine (NAC), dimethyl sulfoxide(DMSO), or ethyl alcohol post infection was shown to further improve virus production in a dose-dependent manner. The serum-free suspension process described here should be suitable for the manufacturing of other E1-deleted AdV vectors and could potentially be used for the production of recombinant proteins by HEK293 cells.

Bayesian methods for meta-analysis of causal relationships estimated using genetic instrumental variables

Genetic markers can be used as instrumental variables, in an analogous way to randomization in a clinical trial, to estimate the causal relationship between a phenotype and an outcome variable. Our purpose is to extend the existing methods for such Mendelian randomization studies to the context of multiple genetic markers measured in multiple studies, based on the analysis of individual participant data. First, for a single genetic marker in one study, we show that the usual ratio of coefficients approach can be reformulated as a regression with heterogeneous error in the explanatory variable. This can be implemented using a Bayesian approach, which is next extended to include multiple genetic markers. We then propose a hierarchical model for undertaking a meta-analysis of multiple studies, in which it is not necessary that the same genetic markers are measured in each study. This provides an overall estimate of the causal relationship between the phenotype and the outcome, and an assessment of its heterogeneity across studies. As an example, we estimate the causal relationship of blood concentrations of C-reactive protein on fibrinogen levels using data from 11 studies. These methods provide a flexible framework for efficient estimation of causal relationships derived from multiple studies. Issues discussed include weak instrument bias, analysis of binary outcome data such as disease risk, missing genetic data, and the use of haplotypes.

Drug treatment of chronic-intermittent abdominal cramping and pain: a multi-national survey on usage and attitudes

BACKGROUND

Data on drug treatment of abdominal cramping and pain are sparse.

AIM

To compare treatment of abdominal cramping and pain across countries worldwide.

METHODS

A multi-national survey was conducted in the USA, Mexico, Brazil, Argentina, Germany, Belgium, Italy and the UK. In each country, approximately 210 people were interviewed on various aspects of drug treatment of their complaints.

RESULTS

In total, 1717 participants were interviewed. Respondents from the Americas used more medication (approximately 90%) than those from Europe (approximately 70%). Over-the-counter remedies were much more used than prescription drugs (except for Mexico). Medication was mainly taken on demand to relieve a pain episode. In the Latin American countries, antispasmodics were most popular (up to 73%), in Germany antacids, and in the UK antacids and analgesics. Regarding expectations of treatment, 'fast onset of action' ranked the highest, followed by 'highly effective' and 'well tolerated'.

CONCLUSIONS

A majority of people afflicted by abdominal cramping and pain use medication and take them on demand. Consequently, rapid onset of action is mentioned as most important. Antispasmodics are the class most frequently used with considerable variation from country to country.

New perspectives on community-acquired pneumonia in 388 406 patients. Results from a nationwide mandatory performance measurement programme in healthcare quality

BACKGROUND

The database of the German programme for quality in healthcare including data of every hospitalised patient with community-acquired pneumonia (CAP) during a 2-year period (n = 388 406 patients in 2005 and 2006) was analysed.

METHODS

End points of the analysis were: (1) incidence; (2) outcome; (3) performance of the CRB-65 (C, mental confusion; R, respiratory rate >or=30/min; B, systolic blood pressure <90 mm Hg or diastolic blood pressure or=65 years) score in predicting death; and (4) lack of ventilatory support as a possible indicator of treatment restrictions. The CRB-65 score was calculated, resulting in three risk classes (RCs).

RESULTS

The incidence of hospitalised CAP was 2.75 and 2.96 per 1000 inhabitants/year in 2005 and 2006, respectively, higher for males (3.21 vs 2.52), and strongly age related, with an incidence of 7.65 per 1000 inhabitants/year in patients aged >or=60 years over 2 years. Mortality (13.72% and 14.44%) was higher than reported in previous studies. The CRB-65 RCs accurately predicted death in a three-class pattern (mortality 2.40% in CRB-65 RC 1, 13.43% in CRB-65 RC 2 and 34.39% in CRB-65 RC 3). The first days after admission were consistently associated with the highest risk of death throughout all risk classes. Only a minority of patients who died had received mechanical ventilation during hospitalisation (15.74%).

CONCLUSIONS

Hospitalised CAP basically is a condition of the elderly associated with a higher mortality than previously reported. It bears a considerable risk of early mortality, even in low risk patients. CRB-65 is a simple and powerful tool for the assessment of CAP severity. Hospitalised CAP is a frequent terminal event in chronic debilitated patients, and a limitation of treatment escalation is frequently applied.

Association between polymorphisms of endothelial nitric oxide synthase gene (NOS3) and left posterior wall thickness (LPWT) of the heart in Fabry disease

Fabry disease is an X-chromosomal storage disorder due to loss-of-function mutations of the GLA gene encoding the lysosomal enzyme α-galactosidase A. Accumulating glycosphingolipid deposits disturb the function of various cells, in particular that of myocytes, arterial smooth-muscle cells, and vascular endothelium. Hypertrophic cardiomyopathy, for example measured by left posterior wall thickness (LPWT) of the heart, represents a major component of Fabry disease morbidity in adult patients. Endothelium-derived nitric oxide (eNO), produced by eNO synthase (eNOS), is a key regulator of vessel wall function and cardiovascular homeostasis. We analysed the effect of the polymorphisms c.894G > T (p.Glu298Asp) in exon 7 and the 27 bp tandem repeat (VNTR; allele a: 4 and allele b: 5 repeats) in intron 4 of the NOS3 gene, encoding eNOS, on LPWT of 102 patients with Fabry disease. For the association analysis, the distance of each patient's LPWT value from the cohort-specific, age-dependent regression line point (expected values) was used. In the cohort of 46 male patients, LPWT mean value of the group with GG genotype at position c.894 was smaller by 1 mm than that of (GT + TT) (p = 0.058). LPWT of patients with bb was thicker by 1.4 mm than that of (ab + aa) (p = 0.022). In patients with haplotype Ga, a thinner LPWT was seen than in those with Tb (p = 0.006). While no correlation was found between the GLA genotype and LPWT, the difference of 2.44 mm between the relative LPWT mean values of the two extreme NOS3 groups corresponds to the absolute LPWT increase that an average male patient with Fabry disease experiences during about 12 years. These are the first data showing a significant association of non-GLA-derived sequence variants with the cardiac phenotype in Fabry disease that may in part explain the great phenotypic variability of the disease.

Myocardial induction of nucleostemin in response to postnatal growth and pathological challenge

Stem cell-specific proteins and regulatory pathways that determine self-renewal and differentiation have become of fundamental importance in understanding regenerative and reparative processes in the myocardium. One such regulatory protein, named nucleostemin, has been studied in the context of stem cells and several cancer cell lines, where expression is associated with proliferation and maintenance of a primitive cellular phenotype. We find nucleostemin is present in young myocardium and is also induced following cardiomyopathic injury. Nucleostemin expression in cardiomyocytes is induced by fibroblast growth factor-2 and accumulates in response to Pim-1 kinase activity. Cardiac stem cells also express nucleostemin that is diminished in response to commitment to a differentiated phenotype. Overexpression of nucleostemin in cultured cardiac stem cells increases proliferation while preserving telomere length, providing a mechanistic basis for potential actions of nucleostemin in promotion of cell survival and proliferation as seen in other cell types.

Evolution of the c-kit-positive cell response to pathological challenge in the myocardium

Cumulative evidence indicates that myocardium responds to growth or injury by recruitment of stem and/or progenitor cells that participate in repair and regenerative processes. Unequivocal identification of this population has been hampered by lack of reagents or markers specific to the recruited population, leading to controversies regarding the nature of these cells. Use of a transgenic mouse expressing green fluorescent protein driven by the c-kit promoter allows for unambiguous identification of this cell population. Green fluorescent protein (GFP) driven by the c-kit promoter labels a fraction of the c-kit+ cells recognized by antibody labeling for c-kit protein. Expression of GFP by the c-kit promoter and accumulation of GFP-positive cells in the myocardium is relatively high at birth compared with adult and declines between postnatal weeks 1 and 2, which tracks in parallel with expression of c-kit protein and c-kit-positive cells. Acute cardiomyopathic injury by infarction prompts increased expression of both GFP protein and GFP-labeled cells in the region of infarction relative to remote myocardium. Similar increases were observed for c-kit protein and cells with a slightly earlier onset and decline relative to the GFP signal. Cells coexpressing GFP, c-kit, and cardiogenic markers were apparent at 1-2 weeks postinfarction. Cardiac-resident c-kit+ cell cultures derived from the transgenic line express GFP that is diminished in parallel with c-kit by induction of differentiation. The use of genetically engineered mice validates and extends the concept of c-kit+ cells participating in the response to myocardial injury.

Prevalence and management of abdominal cramping and pain: a multinational survey

BACKGROUND

Though functional gastrointestinal complaints are recognised as being common throughout the world, there have been few comparative studies of prevalence.

AIM

To compare the prevalence and management of abdominal cramping/pain in nine countries.

METHODS

In a two-stage community survey, approximately 1000 subjects were interviewed in each of nine countries to establish the demographics of individuals with abdominal cramping/pain (stage 1) followed by market research-driven interviews with >or=200 sufferers per country (stage 2).

RESULTS

9042 subjects were interviewed in stage 1. Mexico (46%) and Brazil (43%) had the highest prevalence of abdominal cramping/pain; Japan the lowest (10%). Abdominal cramping/pain was more common in women (12-55%) than in men (7-38%). About 1717 subjects participated in stage 2; 65% were women and the average age at symptom onset was 29 years. The frequency of episodes differed between countries, being highest in the US (61% suffered at least once in a week). Sufferers in the US and Latin America reported a higher usage of medications (around 90%) than those in Europe (around 72%). In most countries over-the-counter drugs were principally used. Antispasmodic drugs were most popular in Latin America and Italy, antacids in Germany and the UK. Drug therapy decreased the duration of episodes (by up to 81% in Brazil).

CONCLUSIONS

The community prevalence, severity, healthcare seeking and medication usage related to abdominal cramping/pain are high overall, but vary considerably between countries.

Akt promotes increased cardiomyocyte cycling and expansion of the cardiac progenitor cell population

Activation of Akt is associated with enhanced cell cycling and cellular proliferation in nonmyocytes, but this effect of nuclear Akt accumulation has not been explored in the context of the myocardium. Cardiac-specific expression of nuclear-targeted Akt (Akt/nuc) in transgenics prolongs postnatal cell cycling as evidenced by increased numbers of Ki67+ cardiomyocytes at 2 to 3 weeks after birth. Similarly, nuclear-targeting of Akt promotes expansion of the presumptive cardiac progenitor cell population as assessed by immunolabeling for c-kit in combination with myocyte-specific markers Nkx 2.5 or MEF 2C. Increases in pro-proliferative cytokines, including tumor-necrosis superfamily 8, interleukin-17e, and hepatocyte growth factor, were found in nuclear-targeted Akt myocardial samples. Concurrent signaling mediated by paracrine factors downstream of Akt/nuc expression may be responsible for phenotypic effects of nuclear-targeted Akt in the myocardium, including enhanced cell proliferation and expansion of the stem cell population.