Genetic and transgenic approaches to dissecting muscle development and contractility using the Drosophila model system

Both genetic and transgenic analyses of Drosophila melanogaster, the common fruit fly, are providing important insights into the mechanisms of muscle cell determination and development, myofibril assembly, and muscle contraction. This model system affords tremendous advantages such as ease of isolating mutants defective in these processes, determining the identity of affected genes, and analyzing protein function by transformation with in vitro mutagenized versions of such genes. These approaches have identified a series of proteins that are critical to mesoderm and muscle determination, many of which are likely to serve similar roles in vertebrates. The effects of mutating structural protein genes upon myofibril assembly and function in Drosophila help to define the differential roles of contractile protein isoforms and the importance of proper protein stoichiometry for physiologic function. These studies may also provide insight into the role of structural proteins in vertebrate contractility.     

Epidemiology of Crohn's disease and ulcerative colitis in a central Canadian province: a population-based study.

The aim of this study was to assess the accuracy and utility of administrative health data in identifying persons with inflammatory bowel disease on a population basis and to determine the incidence and prevalence of this disease in the Canadian province of Manitoba. The data from Manitoba Health (the province's single insurer) were used to identify residents with physician and/or hospital contacts for Crohn's disease or ulcerative colitis based on International Classification of Diseases, Ninth Revision, Clinical Modification, codes between 1984 and 1995. Of 5,182 eligible individuals, 4,514 were mailed questionnaires and 2,725 responded. Cases were defined as individuals with five or more separate medical contacts with one of these diagnoses or three or more such contacts if they were resident for less than 2 years. The accuracy of the study case definitions was high when compared with either self-report or chart review. The 1989-1994 age- and sex-adjusted annual incidence was 14.6/100,000 for Crohn's disease and 14.3/100,000 for ulcerative colitis. The prevalence of Crohn's disease in 1994 was 198.5/100,000, and that of ulcerative colitis was 169.7/100,000. In conclusion, the authors have successfully established and validated a population-based database of inflammatory bowel disease based on administrative data. The high incidence rates and dynamic epidemiology of inflammatory bowel disease in Manitoba indicate the presence of important environmental risk factors, which warrants further investigation.     

A time-saving technique for the treatment of simple phobias

Two cases are presented in detail and two in summary fashion to illustrate a technique that can frequently be used instead of systematic desensitization to reduce the time needed to treat simple phobias. This method combines techniques developed by Strategic Therapy and Critical Incident Debriefing. Symptoms that the patient experiences as out of control are prescribed by the therapist and then normalized. For example, a 26-year-old woman with a fear of social situations learns that it is not unusual for people to feel somewhat awkward and anxious as they try to reestablish themselves with friends after being away from them for a long period of time. Therapy taught her to accept rather than fight her initial anxiety in these situation. Another client with claustrophobia was taught to imagine himself getting anxious and telling himself, "yes, this is exactly what I expect. I am going to get anxious, and my anxiety will increase, but it isn't going to get higher than a '5' (on a 1-10 scale), and I can handle that." When these interventions are successful, the anxiety initially experienced in a phobic situation as a signal for panic is reinterpreted in new situations as expectable. This reframing renders the anxiety manageable. The treatment of two additional patients is briefly presented to further illustrate the application of this approach. Their phobias included a fear of sweating in public and a fear of sleep.     

Depression, illness perception and coping in rheumatoid arthritis

This study aimed to establish the relationship between depression, illness perception, coping strategies, and adverse childhood events in rheumatoid arthritis patients. Sixty-two out-patients with rheumatoid arthritis (RA) completed the Hospital Anxiety and Depression Scale, Illness Perception Questionnaire, London Coping with Rheumatoid Arthritis Questionnaire, and Childhood Development Questionnaire, and underwent a clinical assessment of their physical state. Depressed patients were more disabled than the nondepressed, had a more negative view of their illness, and used more negative coping strategies. There was no association between depression and childhood adversity. Once disability was controlled for, there continued to be a significant correlation between depression and: (i) viewing the consequences of the illness negatively (Spearman's correlation coefficient [r]=0.37, p=0.003); and (ii) the perceived ability to control the illness (r= -0.26, p=0.04). The relationship between depression and negative coping strategies became insignificant. This study indicates the close relationship between depression and a negative view of the illness.     

Vascularization of human glioma spheroids implanted into rat cortex is conferred by two distinct mechanisms

Aim of this study was to develop and characterize an applicable in vivo model to investigate angiogenesis of human gliomas. An established glioblastoma spheroid model was used to investigate the neovascularization of a standardized avascular solid tumor mass. Spheroids of two human glioma cell lines were labeled with an in vivo fluorescent dye. Single spheroids were implanted into the cortex of athymic rats. After 1, 3, 7, 14, and 21 days, brain sections containing the spheroid were immunostained for endothelial cells or vascular endothelial growth factor (VEGF). The dye-stained glioma spheroid and the endothelial cells were visualized by confocal microscopy. Two distinct mechanisms of tumor vascularization could be observed. (1) "Classical" angiogenesis with new vessels sprouting from existing host vessels into the spheroid was seen. (2) Individual endothelial cells were found to migrate towards and into the center of the spheroid where they coalesced to form new vessels. This process occurred as early as 24 hr after spheroid implantation. Spheroid vascularization was accompanied by an increase of VEGF expression, which peaked 7 days after implantation and returned to normal patterns by 14-21 days. Besides the "classical" angiogenesis by angiogenic blood vessels, the recruitment of individual endothelial cells seems to be an additional mechanism in early glioma vascularization. Our model proves to be a reliable, reproducible system to study in vivo angiogenesis of human gliomas.     

SYMPOSIUM: Experimental Biology 1995 Role of Mesangial Cell Ion Transport in Glomerular Physiology and Disease: ANGIOTENSIN II-INDUCED TYROSINE PHOSPHORYLATION IN MESANGIAL AND VASCULAR SMOOTH MUSCLE CELLS

• 1 Angiotensin II (AngII)-induced, activation of phospholipase C (PLC) and Ca²⁺-dependent Cl^? channels is an important signal transduction pathway for the regulation of vascular smooth muscle cell (VSMC) and glomerular mesangial cell contraction and growth. While AT receptors are traditionally thought to be G-protein coupled to the β isoform of PLC, recent evidence suggests that in some tissues AT receptors may also activate the PLC-γ isoform via tyrosine phosphorylation.
• 2 By western analysis, we identified PLC-γ1 in the above cell types. We found that within 3 min of exposure to 10^?7 mol/L AngII, tyrosine phosphorylation of PLC-γ1 was observed; however, peak response (> 3-fold increase) occurred within 0.5 min. In addition, pre-incubation of these cells with the tyrosine kinase inhibitor genistein blocked the tyrosine phosphorylation of PLC-γ1 by AngII. In contrast, preincubation with the tyrosine phosphatase inhibitor sodium vanadate increased the levels of tyrosine phosphorylation of PLC-γ1. Similar results were found when intracellular levels of 1,4,5-IP₃ were measured after AngII exposure.
• 3 By using patch clamp techniques on cultured rat mesangial cells exposed to AngII, we found that the release of 1,4,5-IP₃-sensitive intracellular Ca²⁺ stores stimulated low conductance Cl^? channels. Preincubation with genistein, abolished the usual 10-fold increase in Cl^? channel activity observed with AngII.
• 4 Therefore, we conclude that in VSMC and glomerular mesangial cells (i) AngII transiently stimulates PLC activity via tyrosine phosphorylation of the γ1 isoenzyme, (ii) tyrosine phosphorylation of PLC-γ1 and production of 1,4,5-IP₃ in response to AngII is dramatically inhibited by tyrosine kinase inhibition and stimulated by tyrosine phosphatase inhibition, (iii) activation of Ca²⁺-dependent Cl^? channels by AngII-induced release of 1,4,5-IP₃-dependent intracellular Ca²⁺ stores is also abolished by tyrosine kinase inhibition. In summary, this AngII-induced signal transduction cascade provides a possible mechanism for both the contractile and growth-stimulating effects of AngII on VSMC and glomerular mesangial cells.

     

DNA-protein crosslinks as a biomarker of cis-platinum activity in cancer patients

We have developed a new method to assess the amount of DNA-protein crosslinks (DNA-PC) in peripheral lymphocytes, based on the selective precipitation of the DNA crosslinked to proteins. We assessed the amount of DNA-PC in peripheral lymphocytes of 18 cancer patients who underwent chemotherapy with cis-platinum for the first time. Since the chemotherapy was administered over a two-day period, blood samples were drawn at baseline (before starting the therapy), 4 h after the infusion of the first dose of cis-platinum, the next day (24 h after the first dose, and immediately before the infusion of the second dose), and 2 days later (48 h after the first dose). The mean change of DNA-PC 4 h after therapy was 0.8+/-0.8% (p=0.006), 0.5+/-0.6% after 1 day (p=0.007), and 0.1+/-0.5% after two days (ns). The correlation between DNA-PC changes and cumulative dose of cis-platinum was -0.22 at 4 h, -0.19 after 1 day, and -0.68 at 2 days (p=0.005). The crosslinking effect of cis-platinum seems to vary among individuals and with dose; the DNA-PC may be used to define sub-populations of patients with various degree of sensitivity to the pharmacologic action of this chemotherapeutic agent, and thus to adjust the dosage on an individual basis.     

Linking evaluation and program development. The case of AHCPR-supported clinical practice guidelines

Within a research organization such as the Agency for Health Care Policy and Research (AHCPR), the process of evaluating program performance must often be integrated with a larger research and development agenda. The blending of evaluation and program development (research and development activities undertaken to build expertise and knowledge in a specific programmatic area) can both strengthen the quality of a program and enhance the science of evaluation research. This article describes AHCPR's evaluation strategy and highlights evaluation activities for the agency's clinical practice guideline program. A case study is presented to illustrate the unique methodological challenges in guideline evaluation, the creation of new tools and approaches for evaluating clinical quality, and the benefits of linking evaluation research with program development.     

"Masked" Ph1 chromosome abnormalities in CML: a report of two unique cases

Two patients with chronic myeloid leukemia (CML) showed previously undescribed variants of a "masked" Ph1 abnormality. The first patient had the karyotype 46,XY, + 21, -9, -22, +mar9,mar18 at presentation in the chronic phase. The dicentric marker 9 was interpreted as representing the usual translocation of 22q11 to 9q34, followed by translocation of the Ph1 chromosome (the deleted 22) to 9p and probable translocation of 9p to the distal long arm of the marker. The patient developed clones containing 2 and 3 copies of the "Ph1-containing" marker 9 concomitant with the metamorphosis of his disease to a more aggressive phase. The second case presented with the karyotype 46,XY,- 9,-22,+two D-group markers. A complex rearrangement of chromosomes 9 and 22 is postulated, with interstitial insertion of either 9p or distal 9q into chromosome 22q11. This patient is still in the chronic phase of his disease 9 mo after presentation. The common denominator in these unusual "masked" cases is the 22q11 breakpoint. The paucity of published reports of duplication of 9q + without concurrent duplication of the Ph1 chromosome, supported by the findings in our first case, leads us to conclude that the amplification of genes on the Ph1 chromosome are more important for the evolution of the abnormal stem cell in CML than the chromosome 9 derivative.