Analysis of receptor-G protein interactions in permeabilized cells

Receptor-induced binding of the stable GTP analogue, guanosine 5-[-thio]triphosphate (GTP [S]), to guanine nucleotide-binding regulatory proteins (G proteins) was measured in various permeabilized cells. In myeloid differentiated human leukemia (HL-60) cells, permeabilized with either digitonin, streptolysin O or Staphylococcus aureus -toxin, binding of GTP [S] induced by three distinct chemoattractant receptors was observed. The extent of receptor-stimulated GTP [S] binding (maximally about 2-fold) was independent of the type of permeabilizing agent used. In human erythroleukemia cells permeabilized with digitonin, agonist activation of thrombin and neuropeptide Y receptors increased GTP [S] binding by 1.8- and 1.5-fold, respectively. Finally, in adherently grown human embryonic kidney cells permeabilized with digitonin, activation of the stably expressed human muscarinic m3 receptor increased GTP[S] binding by about 1.6-fold. In digitonin-permeabilized HL-60 cells, a quantitative analysis of formyl peptide receptors and interacting G proteins was performed. About 50,000 formyl peptide receptors per cell were detected. Agonist binding to these receptors was fully sensitive to regulation by guanine nucleotides and pertussis toxin. The number of high-affinity GTP [S] binding sites, most likely representing heterotrimeric G proteins, was calculated to be about 670,000 per cell. Stimulation of formyl peptide receptors led to the activation of about 130,000 of high-affinity GTP [S] binding sites, indicating a ratio of about three activated G proteins per one agonist-activated receptor.Overall, this study indicates that receptor-stimulated GTP [S] binding to G proteins in permeabilized cells is a sensitive and rapid method for analyzing receptor-G protein interactions, which can be applied to a variety of cultured cells and for various receptor systems.     

Birth Outcomes of Immigrant Women in the United States,France, and Belgium

Objectives: To compare maternal characteristics and birth outcomes of Mexico-born and native-born mothers in the United States and those of North African mothers living in France and Belgium to French and Belgian nationals. Methods: We examined information from single live birth certificates for 285,371 Mexico-born and 3,131,632 U.S.-born mothers (including 2,537,264 U.S.-born White mothers) in the United States, 4,623 North African and 103,345 Belgian mothers in Belgium, and a French national random sample consisting of 632 North African and 11,185 French mothers. The outcomes were mean birthweight, low birthweight, and preterm births. Differences between native/nationals and foreign-born mothers in each country were assessed in bivariate and multivariate analyses controlling for maternal risk factors. Results: The adjusted odds for low birthweight were lower for immigrants than native/nationals by 32% in the United States, by 32% in Belgium, and by 30% in France. The adjusted odds for preterm births were lower for immigrants compared with native/nationals by 11% in the United States and by 23% in Belgium. In France, the odds for preterm births were comparable for immigrants and naturalized mothers. Infants of immigrant mothers also had higher mean birthweights in all three countries. Conclusion: Despite their disadvantaged status, Mexico-born and North African-born women residing in the United States, France, and Belgium show good birth outcomes. These cannot be explained solely by traditional risk factors. Protective factors and selective migration may offer further clues.     

The effect of ultra-high molecular weight polyethylene wear debris on MG63 osteosarcoma cells in vitro

BACKGROUND: Focal osteolysis due to ultra-high molecular weight polyethylene wear debris involves effects on both bone resorption and bone formation. METHODS: The response of MG63 osteoblast-like osteosarcoma cells to ultra-high molecular weight polyethylene wear debris isolated by enzymatic digestion of granulomatous tissue obtained from the sites of failed total hip arthroplasties was examined. Scanning electron microscopy, particle-size analysis, and Fourier transform infrared spectroscopy were used to characterize the number, morphology, size distribution, and chemical composition of the particles. Cell response was assessed by adding particles at varying dilutions to confluent cultures and measuring changes in cell proliferation (number of cells and [3H]-thymidine incorporation), osteoblast function (alkaline-phosphatase-specific activity and osteocalcin production), matrix production (collagen production and proteoglycan sulfation), and local cytokine production (prostaglandin-E2 production). RESULTS: The mean size of the particles was 0.60 micrometer, and 95 percent of the particles had a size of less than 1.5 micrometers. The number of particles per gram of tissue ranged from 1.39 to 3.38x10(9). Three of the four batches of particles were endotoxin-free. Exposure of the cells to particles of wear debris significantly increased the number of cells (p<0.05) and the [3H]-thymidine incorporation (p<0.05) in a dose-dependent manner. In contrast, the addition of particles decreased alkaline-phosphatase-specific activity and osteocalcin production. Collagen production and proteoglycan sulfation were also decreased, while prostaglandin-E2 synthesis was increased by the addition of particles. CONCLUSIONS: Ultra-high molecular weight polyethylene particles isolated from human tissue stimulated osteoblast proliferation and prostaglandin-E2 production and inhibited cell differentiation and matrix production. These results indicate that particles of wear debris inhibit cell functions associated with bone formation and that osteoblasts may produce factors in response to wear debris that influence neighboring cells, such as osteoclasts and macrophages. CLINICAL RELEVANCE: Particles of wear debris, especially ultra-high molecular weight polyethylene, have been implicated in the loosening of implants and the development of osteolysis. The present study shows that particles of ultra-high molecular weight polyethylene isolated from human tissue inhibit osteoblast functions associated with bone formation. In addition, particles of wear debris induced osteoblasts to secrete factors capable of influencing neighboring cells, such as osteoclasts and macrophages. These results suggest that osteoblasts may play a role in the cascade of events leading to granuloma formation, osteolysis, and failure of orthopaedic implants.     

Research utilization models: frameworks for implementing evidence-based occupational therapy practice

Evidence-based practice is an important step in the professional evolution of occupational therapy and also provides the means for state-of-the-art innovative clinical service for clients. An essential step in incorporating innovations and developments into clinical practice is through research utilization. Nine models of research utilization developed in the literature are reviewed and critiqued. These are: (1) the Conduct and Utilization of Research in Nursing (CURN) Project; (2) the Stetler-Marram Model; (3) the University of North Carolina Approach; (4) the Innovation Diffusion Process Model; (5) Killeen's Matrix of Research Activity; (6) the Iowa Model of Research In Practice; (7) the Western Interstate Commission for Higher Education In Nursing Project; (8) the Nursing Child Assessment Satellite Training Project; and (9) the Linkage Model. Research utilization models provide a framework for collaboration and the necessary conditions for research utilization activities to be successful. Copyright © 1999 Whurr Publishers Ltd.     

Histological and quantitative effects of sublethal cyanide exposure on oocyte development in rainbow trout

Sexually maturing female rainbow trout were exposed in the laboratory to 0.01 mg/L and 0.02 mg/L hydrogen cyanide (HCN) for 20 days at 10 ±0.5C. Histological sections of ovaries from these fish indicated abnormal cytoplasmic features among oocytes during their early development. Oocytes exposed to cyanide during late development exhibited altered patterns of secondary yolk deposition. Quantitative observations similarly confirm delays in secondary yolk deposition. Exposure of females to 0.02 mg/L HCN during early summer ovarian growth resulted in delayed secondary yolk deposition among 93% of the oocytes when compared with controls. When fish were exposed during mid-summer, the effects were evident at both concentrations with approximately 60% of the oocytes failing to reach the secondary yolk deposition stage at the completion of the experiment. This was further substantiated by potential growth studies which indicated a complete absence of oocytes in the final stages of secondary yolk deposition at both cyanide concentrations as compared with controls which contained 27%. The high frequency of atresia at both concentrations suggested that oocytes unable to produce secondary yolk were resorbed by the ovary through a unique form of atresia. It is also suggested that levels of cyanide as low as 0.01 mg/L have a critical effect upon the process of secondary yolk deposition within the ovary and thus significantly reduce the number of viable eggs.     

Pharmacy residency training in academic medical centers.

PURPOSE: A survey of U.S. academic medical centers (AMCs) was conducted to identify the most important and challenging issues in pharmacy residency training. METHODS: A questionnaire addressing program characteristics and residency training concerns was sent electronically to pharmacy directors at 130 AMCs that are members or associate members of the University HealthSystem Consortium (UHC). Residency coordinators for both pharmacy practice and specialized programs were asked to complete the questionnaire, with input from other pharmacists involved in the residency program. Respondents were asked to rate the importance and degree of challenge for all issues on a 5-point Likert scale, where 1 = least important or least challenging and 5 = most important or most challenging. RESULTS: Responses were received from hospitals representing over 60% of all residency positions offered by UHC member hospitals. Recruitment was rated the most important issue (mean importance score, 4.8) facing residency programs in AMCs, but with over 85% of budgeted positions filled, programs appear to be successful in overcoming this concern. The most challenging issue (mean challenge score, 4.2) was compliance with the evaluation and documentation elements of the ASHP Residency Learning System (RLS), a system often used to meet requirements for pharmacy practice residency accreditation. The completion of resident research requirements was ranked as both an important and a challenging issue (mean importance score, 4.5; mean challenge score, 3.9). CONCLUSION: A survey of AMCs showed that they offered a wide variety of pharmacy residency programs and filled most budgeted resident positions. Resident recruitment, the RLS, and research requirements are the most important and challenging residency concerns facing the respondents.     

Antitumor alkylating agents: in vitro cross-resistance and collateral sensitivity studies

Cell lines resistant to five antitumor alkylating agents (CDDP, PAM, 4-HC, HN2, and BCNU) were developed from five parental human tumor lines representative of solid tumors with a range of sensitivities to antitumor alkylating agents. The parental cell lines were SCC-25 squamous carcinoma of the head and neck, MCF-7 breast carcinoma, SW2 small-cell lung cancer, SL6 non-small-cell lung carcinoma, and G3361 melanoma. Survival curves using colony formation as the endpoint were generated for each of the 25 cell lines to each of the five alkylating agents. Comparison of the drug concentrations that reduced the survival of the alkylating agent-resistant cell lines by 90% (IC₉₀ values) with the IC₉₀ values obtained for the corresponding parental cell lines was used as a measure of the resistance/sensitivity of the alkylating agent-resistant lines to each drug tested. Although cross-resistance among the alkylating agents was generally uncommon, several patterns of response emerged. Cross-resistance occurred in 27 of the 105 determinations and occurred most frequently in the cell lines in which resistance was developed to PAM (57%) or BCNU (38%). Cross-resistance to HN2 occurred most frequently. Collateral sensitivity was equally as common, occurring in 25 of the 105 determinations. Collateral sensitivity occurred most frequently in the cell lines made resistant to 4-HC. The 4-HC-resistant cell lines were most frequently collaterally sensitive to PAM and to BCNU. Cross-resistance developed most frequently in the MCF-7 breast carcinoma and SCC-25 squamous-cell carcinoma cell lines, whereas collateral sensitivity developed most frequently in the SW2 small-cell lung cancer line and the G3361 melanoma cell line and least frequently in the MCF-7 breast carcinoma cell line and the SL6 non-small-cell lung cancer cell line. The implication of these findings for the development of strategies for clinical treatment are discussed.Abbreviations AAs antitumor alkylating agents - CDDP cisplatin,cis-diamminedichloroplatinum(II) - HN2 nitrogen mustard - BCNU N,N-bis(2-chloroethyl)-N-nitrosourea - PAM l-phenylalanine mustard, melphalan - 4-HC 4-hydroxyperoxycyclophosphamide - CPA cyclophosphamide - THIO trimethyleneiminethiophosphoramide - DME Dulbecco's modified Eagle's medium - IC₉₀ 90% inhibitory concentration - PBS phosphate-buffered 0.9% saline - FBS fetal bovine serum - GSH glutathione - GST glutathione-S-transferase This work was supported by NIH grant PO1-38493, by a grant from the Mathers Foundation, by a grant from Bristol-Myers-Squibb, Inc., Wallingford, Connecticut, and by ACS grant CH-487