The receptor tyrosine kinases: role in cancer progression

The last two decades have witnessed significant progress in the understanding of the basic mechanisms underlying tumor growth and metastasis. Receptor tyrosine kinases play a central role in cell proliferation and differentiation, cell survival, cell motility, invasion, and angiogenesis, all of which contribute to tumor progression. Alterations at the level of the receptor and its ligand lead to the activation of a number of signaling pathways, each of which may contribute to cancer progression. The dissection of the molecular changes associated with neoplastic growth have provided pharmaceutical companies with a range of targets for drug intervention. This article highlights the deregulation of receptor tyrosine kinases in human cancers and their involvement in metastasis.     

A Case-Control Assessment of Risk Factors for Gallbladder Carcinoma

Gallbladder carcinoma is an uncommon, but highlyfatal disease. Its symptoms frequently mirror those ofgallstone disease, and in most instances, diagnosis isan incidental finding at surgery. While risk factors have been suggested for this cancer,many may in reality simply be a consequence of the olderage of the population. This study is one of the few toapproach this question by using a case-control study design comparing gallbladder carcinomapatients with a gallstone population, coupled withmultivariate analysis to determine age-independent riskfactors. Univariate analyses showed gallbladdercarcinoma patients to be older than gallstone patientsand to have many age-associated diseases. Followingmultiple regression adjustment for age, this disease wasassociated with female gender and with a previous history of gallstone symptoms. Carcinomapatients were less likely to have cholesterol gallstonesin their gallbladders at surgery. A previous history ofsmoking was a substantial risk but of borderline statistical significance. Previous studiesreport associations that may be due to the older age ofthe gallbladder carcinoma patient. Our results show thatafter adjusting for age with multivariate analysis, gallbladder cancer subjects were predominantlyfemale, more likely to report previous gallstonesymptomology, and to smoke. While gallstones were notuniversally isolated from carcinoma patients atcholecystectomy, when present, they were less frequentlyclassified as cholesterol gallstones based on visualinspection. Further cohort studies which target thesepopulations will allow us to gain a more solid consensus on the risk factors for this disease.     

Multipotential neural precursors transplanted into the metachromatic leukodystrophy brain fail to generate oligodendrocytes but contribute to limit brain dysfunction

Neural stem cells appear to be best suited for regenerative therapy in neurological diseases. However, the effects of high levels of potentially toxic substances such as sulfatides--which accumulate in metachromatic leukodystrophy (MLD)--on this regenerative ability are still largely unclear. To start addressing this question, in vitro and in vivo experiments were used to examine the behavior of multipotential neural precursors exposed to abnormally high levels of sulfatides. Following transplantation of dissociated neurospheres into the brain of presymptomatic MLD pups, the majority of donor-derived cells were distributed in a caudal to rostral direction, with higher numbers in the cortex. Most if not all of the donor cells acquired an astroglial phenotype. We found no evidence of oligodendrocyte or neuronal commitment of transplanted cells in long-term-treated MLD mice (e.g. up to 1.5 years of age). This was in line with our in vitro findings of sulfatides blocking oligodendrocyte formation after induction of differentiation in sulfatide-treated epidermal growth factor/fibroblast growth factor responsive neurospheres. Transplanted MLD mice showed an improved arylsulfatase A (ARSA) activity and a significant amelioration of sulfatide metabolism, neurodegeneration and motor-learning/memory deficits. Furthermore, transplanted cells were shown to act as a source of ARSA enzyme that accumulated in endogenous brain cells, indicating the occurrence of enzyme cross-correction between transplanted and host cells. These results provide a first insight into the effect of sulfatides on the stemness properties of neural stem cells and on the effects of the MLD environment on the in vivo expectations of using neural stem cells in cell therapy.     

A novel, immortal, and multipotent human neural stem cell line generating functional neurons and oligodendrocytes

The discovery and study of neural stem cells have revolutionized our understanding of the neurogenetic process, and their inherent ability to adopt expansive growth behavior in vitro is of paramount importance for the development of novel therapeutics based on neural cell replacement. Recent advances in high-throughput assays for drug development and gene discovery dictate the need for rapid, reproducible, long-term expansion of human neural stem cells (hNSCs). In this view, the complement of wild-type cell lines currently available is insufficient. Here we report the establishment of a stable human neural stem cell line (immortalized human NSCs [IhNSCs]) by v-myc-mediated immortalization of previously derived wild-type hNSCs. These cells demonstrate three- to fourfold faster proliferation than wild-type cells in response to growth factors but retain rather similar properties, including multipotentiality. By molecular biology, biochemistry, immunocytochemistry, fluorescence microscopy, and electrophysiology, we show that upon growth factor removal, IhNSCs completely downregulate v-myc expression, cease proliferation, and differentiate terminally into three major neural lineages: astrocytes, oligodendrocytes, and neurons. The latter are functional, mature cells displaying clear-cut morphological and physiological features of terminally differentiated neurons, encompassing mostly the GABAergic, glutamatergic, and cholinergic phenotypes. Finally, IhNSCs produce bona fide oligodendrocytes in fractions up to 20% of total cell number. This is in contrast to the negligible propensity of hNSCs to generate oligodendroglia reported so far. Thus, we describe an immortalized hNSC line endowed with the properties of normal hNSCs and suitable for developing the novel, reliable assays and reproducible high-throughput gene and drug screening that are essential in both diagnostics and cell therapy studies.     

Effect of dietary cholesterol and indomethacin on cholelithiasis and gallbladder motility in guinea pig

This study examines the effects of dietary cholesterol and subcutaneous indomethacin on gallstone formation, gallbladder motility, and bile composition in guinea pigs. Guinea pigs on cholesterol diets developed gallstones which were not primarily composed of cholesterol and were not prevented by indomethacin. Animals receiving cholesterol diets showed significant gallbladder enlargement which was inhibited by indomethacin. Cholesterol did not alter gallbladder pressure-volume relationships or the response to CCK, while indomethacin diminished gallbladder tone. Although cholesterol feeding did not appear to alter smooth muscle contractility in the guinea pig gallbladder, it caused significant gallbladder enlargement by a mechanism which may be dependent on prostaglandins.This study was supported by National Institutes of Health grant AM 15304.     

Teaching surgical decision-making: an interactive, web-based approach

BACKGROUND: Skillful surgical care demands proper patient assessment and decision-making. These skills are honed through long hours and years of clinical practice. A decrease in work hours is reducing the number of cases managed by medical students and residents. We have developed a set of interactive, web-based teaching modules to help fill this gap. MATERIALS AND METHODS: The modules aim to teach surgical decision-making in a convenient, nonthreatening manner. Surgical case material is presented in a graphically rich environment, including video and sound to enhance realism. At the end of each web-page, the user must make a management decision. The correct answer is subsequently provided with immediate feedback. Medical students used and evaluated the modules during their surgical clerkships. Additionally, students took a pretest and 1-week delayed posttest after completing the modules to assess the program's efficacy. RESULTS: Eight modules involving pediatric and general surgery have been completed. Medical students gave high ratings to the quality of the modules and found the interactive format both engaging and educationally effective. Eighty-seven percent of medical students rated the program's educational value as above average to excellent. On pre- and posttest analysis, students' scores improved an average of 24.8% (P < 0.001). CONCLUSION: Students enjoy web-based educational material. Additional modules covering a range of surgical topics are in development. Web-based modules appear to be an effective clinical teaching tool, well-suited for integration into the clinical curriculum.     

Preclinical Profile of BI 224436, a Novel HIV-1 Non-Catalytic-Site Integrase Inhibitor

BI 224436 is an HIV-1 integrase inhibitor with effective antiviral activity that acts through a mechanism that is distinct from that of integrase strand transfer inhibitors (INSTIs). This 3-quinolineacetic acid derivative series was identified using an enzymatic integrase long terminal repeat (LTR) DNA 3′-processing assay. A combination of medicinal chemistry, parallel synthesis, and structure-guided drug design led to the identification of BI 224436 as a candidate for preclinical profiling. It has antiviral 50% effective concentrations (EC₅₀s) of <15 nM against different HIV-1 laboratory strains and cellular cytotoxicity of >90 μM. BI 224436 also has a low, ∼2.1-fold decrease in antiviral potency in the presence of 50% human serum and, by virtue of a steep dose-response curve slope, exhibits serum-shifted EC₉₅ values ranging between 22 and 75 nM. Passage of virus in the presence of inhibitor selected for either A128T, A128N, or L102F primary resistance substitutions, all mapping to a conserved allosteric pocket on the catalytic core of integrase. BI 224436 also retains full antiviral activity against recombinant viruses encoding INSTI resistance substitutions N155S, Q148H, and E92Q. In drug combination studies performed in cellular antiviral assays, BI 224436 displays an additive effect in combination with most approved antiretrovirals, including INSTIs. BI 224436 has drug-like in vitro absorption, distribution, metabolism, and excretion (ADME) properties, including Caco-2 cell permeability, solubility, and low cytochrome P450 inhibition. It exhibited excellent pharmacokinetic profiles in rat (clearance as a percentage of hepatic flow [CL], 0.7%; bioavailability [F], 54%), monkey (CL, 23%; F, 82%), and dog (CL, 8%; F, 81%). Based on the excellent biological and pharmacokinetic profile, BI 224436 was advanced into phase 1 clinical trials.     

Lung ultrasound in diagnosing and monitoring pulmonary interstitial fluid

Chronic heart failure is a complex clinical syndrome often characterised by recurrent episodes of acute decompensation. This is acknowledged as a major public health problem, leading to a steadily increasing number of hospitalisations in developed countries. In decompensated heart failure, the redistribution of fluids into the pulmonary vascular bed leads to respiratory failure, a common cause of presentation to the emergency department. The ability to diagnose, quantify and monitor pulmonary congestion is particularly important in managing the disease. Lung ultrasound (US) is a relatively new method that has gained a growing acceptance as a bedside diagnostic tool to assess pulmonary interstitial fluid and alveolar oedema. The latest developments in lung US are not because of technological advance but are based on new applications and discovering the meanings of specific sonographic artefacts designated as B-lines. Real-time sonography of the lung targeted to detection of B-lines allows bedside diagnosis of respiratory failure due to impairment of cardiac function, as well as quantification and monitoring of pulmonary interstitial fluid. Lung US saves time and cost, provides immediate information to the clinician and relies on very easy-toacquire and highly reproducible data.     

Functional consequences of a novel uromodulin mutation in a family with familial juvenile hyperuricaemic nephropathy

Background. Familial juvenile hyperuricaemic nephropathy (FJHN)is an autosomal-dominant disorder featuring hyperuricaemia,low fractional urate excretion, interstitial nephritis and chronicrenal failure. The responsible gene UMOD was recently identified.UMOD encodes for uromodulin or Tamm–Horsfall glycoprotein,the most abundant protein in normal urine. We encountered afamily with FJHN and identified a novel UMOD mutation in exon6. Methods. We sequenced the gene in all family members, identifiedthe mutation, and verified its presence in the affected members.We next performed functional studies of the mutant protein byimmunofluorescence and FACS analysis on transfected cells. Results. The mutation p.C347G (c.1039T>G) results in a conservedcysteine to glycine amino acid substitution in the uromodulinzona pellucida (ZP) domain. The cell studies showed that thenovel uromodulin mutation causes a delay in protein export tothe plasma membrane due to its retention in the endoplasmicreticulum. Conclusions. We describe the first reported mutation mappingin the ZP uromodulin domain. Our data provide further evidenceshowing why the excretion of uromodulin is reduced in this syndrome.