Pharmacokinetic model driven infusion of propofol in children

A computer controlled infusion device for propofol was used to induce and maintain general anaesthesia in 20 children undergoing minor surgical procedures. The device was programmed with an adult pharmacokinetic model for propofol. During and after anaesthesia, blood samples were taken for measurement of propofol concentrations and it was found that the values obtained were systematically overpredicted by the delivery system algorithm. New pharmacokinetic microconstants were derived from our data which reflected more accurately the elimination and distribution of propofol in a prospective study involving another 10 children.

Role of substrates and products of PI 3-kinase in regulating activation of Rac-related guanosine triphosphatases by Vav

Mitogen stimulation of cytoskeletal changes and c-jun amino-terminal kinases is mediated by Rac small guanine nucleotide-binding proteins. Vav, a guanosine diphosphate (GDP)-guanosine triphosphate (GTP) exchange factor for Rac that stimulates the exchange of bound GDP for GTP, bound to and was directly controlled by substrates and products of phosphoinositide (PI) 3-kinase. The PI 3-kinase substrate phosphatidylinositol-4,5-bisphosphate inhibited activation of Vav by the tyrosine kinase Lck, whereas the product phosphatidylinositol-3,4,5-trisphosphate enhanced phosphorylation and activation of Vav by Lck. Control of Vav in response to mitogens by the products of PI 3-kinase suggests a mechanism for Ras-dependent activation of Rac.

Comparison of candesartan, enalapril, and their combination in congestive heart failure: randomized evaluation of strategies for left ventricular dysfunction (RESOLVD) pilot study. The RESOLVD Pilot Study Investigators

BACKGROUND

We investigated the effects of candesartan (an angiotensin II antagonist) alone, enalapril alone, and their combination on exercise tolerance, ventricular function, quality of life (QOL), neurohormone levels, and tolerability in congestive heart failure (CHF).

METHODS AND RESULTS

Seven hundred sixty-eight patients in New York Heart Association functional class (NYHA-FC) II to IV with ejection fraction (EF) <0.40 and a 6-minute walk distance (6MWD) <500 m received either candesartan (4, 8, or 16 mg), candesartan (4 or 8 mg) plus 20 mg of enalapril, or 20 mg of enalapril for 43 weeks. There were no differences among groups with regard to 6MWD, NYHA-FC, or QOL. EF increased (P=NS) more with candesartan-plus-enalapril therapy (0.025+/-0.004) than with candesartan alone (0.015+/-0.004) or enalapril alone(0.015+/-0.005). End-diastolic (EDV) and end-systolic (ESV) volumes increased less with combination therapy (EDV 8+/-4 mL; ESV 1+/-4 mL; P<0.01) than with candesartan alone (EDV 27+/-4 mL; ESV 18+/-3 mL) or enalapril alone (EDV 23+/-7 mL; ESV 14+/-6 mL). Blood pressure decreased with combination therapy (6+/-1/4+/-1 mm Hg) compared with candesartan or enalapril alone (P<0.05). Aldosterone decreased (P<0.05) with combination therapy (23.2+/-5.3 pg/mL) at 17 but not 43 weeks compared with candesartan (0.7+/-7.8 pg/mL) or enalapril (-0.8+/-11. 3 pg/mL). Brain natriuretic peptide decreased with combination therapy (5.8+/-2.7 pmol/L; P<0.01) compared with candesartan (4. 4+/-3.8 pmol/L) and enalapril alone (4.0+/-5.0 pmol/L).

CONCLUSIONS

Candesartan alone was as effective, safe, and tolerable as enalapril. The combination of candesartan and enalapril was more beneficial for preventing left ventricular remodeling than either candesartan or enalapril alone.

Common elements in growth factor stimulation and oncogenic transformation: 85 kd phosphoprotein and phosphatidylinositol kinase activity

The phosphorylation of proteins on tyrosine in vivo and in vitro was examined in 3T3 cells stimulated by platelet-derived growth factor (PDGF) and transformed by polyoma middle T antigen (MTAg) by using an antibody directed against phosphotyrosine (P-tyr). Two common events were observed upon PDGF stimulation or MTAg transformation of cells: the appearance in the immunoprecipitates of an 85 kd phosphoprotein, and increased phosphatidylinositol (PI) kinase activity. In PDGF-stimulated cells, the 85 kd phosphoprotein and PI kinase activity appeared rapidly, within 1 min of growth factor addition. The PI kinase activity and 85 kd phosphorylation were also increased in anti-P-tyr immunoprecipitates from cells transformed by v-fms and v-sis, but not by SV40 T antigen. The presence of the tyrosine-phosphorylated 85 kd protein correlated with PI kinase activity during several purification steps. These results suggest that the 85 kd phosphoprotein, a putative PI kinase, is a substrate for both the PDGF receptor and MTAg/pp60c-src tyrosine kinase activities.

Multiple Ras functions can contribute to mammalian cell transformation

We have developed a generalized approach, using two hybrid interactions, to isolate Ha-Ras effector loop mutations that separate the ability of Ha-Ras to interact with different downstream effectors. These mutations attenuate or eliminate Ha-ras(G12V) transformation of mammalian cells, but retain complementary activity, as demonstrated by synergistic induction of foci of growth-transformed cells, and by the ability to activate different downstream components. The transformation defect of Ha-ras(G12V, E37G) is rescued by a mutant, raf1, that restores interaction. These results indicate that multiple cellular components, including Raf1, are activated by Ha-Ras and contribute to Ha-Ras-induced mammalian cell transformation.

Epigenetic inactivation of RASSF1A in lung and breast cancers and malignant phenotype suppression

BACKGROUND

The recently identified RASSF1 locus is located within a 120-kilobase region of chromosome 3p21.3 that frequently undergoes allele loss in lung and breast cancers. We explored the hypothesis that RASSF1 encodes a tumor suppressor gene for lung and breast cancers.

METHODS

We assessed expression of two RASSF1 gene products, RASSF1A and RASSF1C, and the methylation status of their respective promoters in 27 non-small-cell lung cancer (NSCLC) cell lines, in 107 resected NSCLCs, in 47 small-cell lung cancer (SCLC) cell lines, in 22 breast cancer cell lines, in 39 resected breast cancers, in 104 nonmalignant lung samples, and in three breast and lung epithelial cultures. We also transfected a lung cancer cell line that lacks RASSF1A expression with vectors containing RASSF1A complementary DNA to determine whether exogenous expression of RASSF1A would affect in vitro growth and in vivo tumorigenicity of this cell line. All statistical tests were two-sided.

RESULTS

RASSF1A messenger RNA was expressed in nonmalignant epithelial cultures but not in 100% of the SCLC, in 65% of the NSCLC, or in 60% of the breast cancer lines. By contrast, RASSF1C was expressed in all nonmalignant cell cultures and in nearly all cancer cell lines. RASSF1A promoter hypermethylation was detected in 100% of SCLC, in 63% of NSCLC, in 64% of breast cancer lines, in 30% of primary NSCLCs, and in 49% of primary breast tumors but in none of the nonmalignant lung tissues. RASSF1A promoter hypermethylation in resected NSCLCs was associated with impaired patient survival (P =.046). Exogenous expression of RASSF1A in a cell line lacking expression decreased in vitro colony formation and in vivo tumorigenicity.

CONCLUSION

RASSF1A is a potential tumor suppressor gene that undergoes epigenetic inactivation in lung and breast cancers through hypermethylation of its promoter region.

Absence of cancer-associated changes in human fibroblasts immortalized with telomerase

The ectopic expression of telomerase in normal human cells results in an extended lifespan, indicating that telomere shortening regulates the timing of cellular senescence. As telomerase expression is a hallmark of cancer, we investigated the long-term effects of forced expression of human telomerase catalytic component (hTERT) in normal human fibroblasts. In vitro growth requirements, cell-cycle checkpoints and karyotypic stability in telomerase-expressing cells are similar to those of untransfected controls. In addition, co-expression of telomerase, the viral oncoproteins HPV16 E6/E7 (which inactivate p53 and pRB) and oncogenic HRAS does not result in growth in soft agar. Thus, although ectopic expression of telomerase in human fibroblasts is sufficient for immortalization, it does not result in changes typically associated with malignant transformation.

Invasive aspergillosis. Disease spectrum, treatment practices, and outcomes. I3 Aspergillus Study Group

A review of representative cases of invasive aspergillosis was conducted to describe current treatment practices and outcomes. Eighty-nine physicians experienced with aspergillosis completed case forms on 595 patients with proven or probable invasive aspergillosis diagnosed using modifications of the Mycoses Study Group criteria. Pulmonary disease was present in 56%, with disseminated infection in 19%. The major risk factors for aspergillosis were bone marrow transplantation (32%) and hematologic malignancy (29%), but patients had a variety of underlying conditions including solid organ transplants (9%), AIDS (8%), and pulmonary diseases (9%). Overall, high antifungal failure rates occurred (36%), and complete antifungal responses were noted in only 27%. Treatment practices revealed that amphotericin B alone (187 patients) was used in most severely immunosuppressed patients while itraconazole alone (58 patients) or sequential amphotericin B followed by itraconazole (93 patients) was used in patients who were less immunosuppressed than patients receiving amphotericin B alone. Response rate for patients receiving amphotericin B alone was poor, with complete responses noted in only 25% and death due to or with aspergillosis in 65%. In contrast, patients receiving itraconazole alone or following amphotericin B had death due to or with Aspergillus in 26% and 36%, respectively. These results confirm that mortality from invasive aspergillosis in severely immunosuppressed patients remains high even with standard amphotericin B. Improved responses were seen in the less immunosuppressed patients receiving sequential amphotericin B followed by itraconazole and those receiving itraconazole alone. New approaches and new therapies are needed to improve the outcome of invasive aspergillosis in high-risk patients.

The Biomolecular Interaction Network Database and related tools 2005 update

The Biomolecular Interaction Network Database (BIND) (http://bind.ca) archives biomolecular interaction, reaction, complex and pathway information. Our aim is to curate the details about molecular interactions that arise from published experimental research and to provide this information, as well as tools to enable data analysis, freely to researchers worldwide. BIND data are curated into a comprehensive machine-readable archive of computable information and provides users with methods to discover interactions and molecular mechanisms. BIND has worked to develop new methods for visualization that amplify the underlying annotation of genes and proteins to facilitate the study of molecular interaction networks. BIND has maintained an open database policy since its inception in 1999. Data growth has proceeded at a tremendous rate, approaching over 100 000 records. New services provided include a new BIND Query and Submission interface, a Standard Object Access Protocol service and the Small Molecule Interaction Database (http://smid.blueprint.org) that allows users to determine probable small molecule binding sites of new sequences and examine conserved binding residues.

Relationship between plasma levels of lipopolysaccharide (LPS) and LPS-binding protein in patients with severe sepsis and septic shock

Plasma endotoxin and lipopolysaccharide-binding protein (LBP) levels were measured in a group of 253 patients at the onset of severe sepsis and/or septic shock. Endotoxin levels were significantly greater than control levels (n=33; mean +/- SD, 5.1+/-7.3 pg/mL) in 78.3% of patients. Median endotoxin levels in patients with sepsis were 300 pg/mL (25%-75% interquartile range, 110-726 pg/mL). LBP levels were elevated in 97% of patients compared with normal control values of 4.1+/-1.65 microgram/mL. Median LBP levels in patients with sepsis were 31.2 microgram/mL (interquartile range, 22.5-47.7 microgram/mL). Median endotoxin levels at study entry were more highly elevated (515 vs. 230 pg/mL; P<.01), and LBP levels were less highly elevated (28.0 vs. 33.2 microgram/mL; P<.05) in nonsurvivors than survivors over the 28-day study period. No correlation was found between endotoxin and LBP levels. The quantitative level of both endotoxin and LBP may have prognostic significance in patients with severe sepsis.

Functional requirement of p23 and Hsp90 in telomerase complexes

Most normal human diploid cells have no detectable telomerase; however, expression of the catalytic subunit of telomerase is sufficient to induce telomerase activity and, in many cases, will bypass normal senescence. We and others have previously demonstrated in vitro assembly of active telomerase by combining the purified RNA component with the reverse transcriptase catalytic component synthesized in rabbit reticulocyte extract. Here we show that assembly of active telomerase from in vitro-synthesized components requires the contribution of proteins present in reticulocyte extracts. We have identified the molecular chaperones p23 and Hsp90 as proteins that bind to the catalytic subunit of telomerase. Blockade of this interaction inhibits assembly of active telomerase in vitro. Also, a significant fraction of active telomerase from cell extracts is associated with p23 and Hsp90. Consistent with in vitro results, inhibition of Hsp90 function in cells blocks assembly of active telomerase. To our knowledge, p23 and Hsp90 are the first telomerase-associated proteins demonstrated to contribute to telomerase activity.

A secreted serine-threonine kinase determines virulence in the eukaryotic pathogen Toxoplasma gondii

Toxoplasma gondii strains differ dramatically in virulence despite being genetically very similar. Genetic mapping revealed two closely adjacent quantitative trait loci on parasite chromosome VIIa that control the extreme virulence of the type I lineage. Positional cloning identified the candidate virulence gene ROP18, a highly polymorphic serine-threonine kinase that was secreted into the host cell during parasite invasion. Transfection of the virulent ROP18 allele into a nonpathogenic type III strain increased growth and enhanced mortality by 4 to 5 logs. These attributes of ROP18 required kinase activity, which revealed that secretion of effectors is a major component of parasite virulence.

Heterogeneity of coronary heart disease risk factors in Indian, Pakistani, Bangladeshi, and European origin populations: cross sectional study

OBJECTIVE

To compare coronary risk factors and disease prevalence among Indians, Pakistanis, and Bangladeshis, and in all South Asians (these three groups together) with Europeans.

DESIGN

Cross sectional survey.

SETTING

Newcastle upon Tyne.

PARTICIPANTS

259 Indian, 305 Pakistani, 120 Bangladeshi, and 825 European men and women aged 25-74 years.

MAIN OUTCOME MEASURES

Social and economic circumstances, lifestyle, self reported symptoms and diseases, blood pressure, electrocardiogram, and anthropometric, haematological, and biochemical measurements.

RESULTS

There were differences in social and economic circumstances, lifestyles, anthropometric measures and disease both between Indians, Pakistanis, and Bangladeshis and between all South Asians and Europeans. Bangladeshis and Pakistanis were the poorest groups. For most risk factors, the Bangladeshis (particularly men) fared the worst: smoking was most common (57%) in that group, and Bangladeshis had the highest concentrations of triglycerides (2.04 mmol/l) and fasting blood glucose (6.6 mmol/l) and the lowest concentration of high density lipoprotein cholesterol (0.97 mmol/l). Blood pressure, however, was lowest in Bangladeshis. Bangladeshis were the shortest (men 164 cm tall v 170 cm for Indians and 174 cm for Europeans). A higher proportion of Pakistani and Bangladeshi men had diabetes (22.4% and 26.6% respectively) than Indians (15.2%). Comparisons of all South Asians with Europeans hid some important differences, but South Asians were still disadvantaged in a wide range of risk factors. Findings in women were similar.

CONCLUSION

Risk of coronary heart disease is not uniform among South Asians, and there are important differences between Indians, Pakistanis, and Bangladeshis for many coronary risk factors. The belief that, except for insulin resistance, South Asians have lower levels of coronary risk factors than Europeans is incorrect, and may have arisen from combining ethnic subgroups and examining a narrow range of factors.

IRS-1: essential for insulin- and IL-4-stimulated mitogenesis in hematopoietic cells

Although several interleukin-3 (IL-3)-dependent cell lines proliferate in response to IL-4 or insulin, the 32D line does not. Insulin and IL-4 sensitivity was restored to 32D cells by expression of IRS-1, the principal substrate of the insulin receptor. Although 32D cells possessed receptors for both factors, they lacked the IRS-1--related protein, 4PS, which becomes phosphorylated by tyrosine in insulin- or IL-4--responsive lines after stimulation. These results indicate that factors that bind unrelated receptors can use similar mitogenic signaling pathways in hematopoietic cells and that 4PS and IRS-1 are functionally similar proteins that are essential for insulin- and IL-4--induced proliferation.

International Conference for the Development of a Consensus on the Management and Prevention of Severe Candidal Infections

Because of the rapidly increasing incidence of serious candidal infections, a consensus conference of 22 investigators from the United States, Europe, and Japan was held to discuss strategies for the prevention and treatment of deep-organ infections caused by Candida species. Commonly asked questions concerning the management of candidal infections were selected for discussion by the participating investigators. Possible answers to the questions were developed by the investigators, who then voted anonymously for their preferences. In certain instances, unanimity or a strong consensus was the result. In all cases, the full spectrum of responses was recorded and is presented in this report. The forms of candidal infection addressed included candidemia, candiduria, hepatosplenic candidiasis (chronic systemic candidiasis), candidal endophthalmitis, and candidal peritonitis. Prevention and treatment strategies were considered for patients who have undergone surgery, for neutropenic and nonneutropenic patients, and for patients who have undergone bone marrow and solid organ transplantation. The therapeutic roles of amphotericin B (standard and lipid formulations) and the azoles were considered.

Stimulation of membrane ruffling and MAP kinase activation by distinct effectors of RAS

The RAS guanine nucleotide binding proteins activate multiple signaling events that regulate cell growth and differentiation. In quiescent fibroblasts, ectopic expression of activated H-RAS (H-RASV12, where V12 indicates valine-12) induces membrane ruffling, mitogen-activated protein (MAP) kinase activation, and stimulation of DNA synthesis. A mutant of activated H-RAS, H-RASV12C40 (where C40 indicates cysteine-40), was identified that was defective for MAP kinase activation and stimulation of DNA synthesis, but retained the ability to induce membrane ruffling. Another mutant of activated H-RAS, H-RASV12S35 (where S35 indicates serine-35), which activates MAP kinase, was defective for stimulation of membrane ruffling and induction of DNA synthesis. Expression of both mutants resulted in a stimulation of DNA synthesis that was comparable to that induced by H-RASV12. These results indicate that membrane ruffling and activation of MAP kinase represent distinct RAS effector pathways and that input from both pathways is required for the mitogenic activity of RAS.

Epithelial wound healing enhanced by transforming growth factor-alpha and vaccinia growth factor

Epidermal regeneration following middermal injuries to skin requires both proliferation and migration of keratinocytes. Epidermal growth factor (EGF) stimulates the proliferation of keratinocytes in culture, and topical administration of EGF accelerates epidermal regeneration of partial thickness burns or split-thickness incisions in vivo. Transforming growth factor-alpha (TGF-alpha) and vaccinia growth factor (VGF) have substantial sequence homology with EGF, and all appear to bind to the same receptor protein. Whether TGF-alpha or VGF can affect epidermal wound healing in vivo is not known. The present studies show that topical administration of TGF-alpha or VGF in antibiotic cream to partial thickness burns (second degree) accelerated epidermal regeneration in comparison with untreated or vehicle-treated burns. Low levels of both TGF-alpha and VGF (0.1 microgram per milliliter) appeared to be more effective than EGF in stimulating epidermal regeneration. Regenerated epithelium from burns treated with TGF-alpha or VGF appeared normal histologically. This finding suggests that topical application of selected growth factors may be useful in accelerating healing of partial thickness injuries.

Oncogenic Ras activation of Raf/mitogen-activated protein kinase-independent pathways is sufficient to cause tumorigenic transformation

Substantial evidence supports a critical role for the activation of the Raf-1/MEK/mitogen-activated protein kinase pathway in oncogenic Ras-mediated transformation. For example, dominant negative mutants of Raf-1, MEK, and mitogen-activated protein kinase all inhibit Ras transformation. Furthermore, the observation that plasma membrane-localized Raf-1 exhibits the same transforming potency as oncogenic Ras suggests that Raf-1 activation alone is sufficient to mediate full Ras transforming activity. However, the recent identification of other candidate Ras effectors (e.g., RalGDS and phosphatidylinositol-3 kinase) suggests that activation of other downstream effector-mediated signaling pathways may also mediate Ras transforming activity. In support of this, two H-Ras effector domain mutants, H-Ras(12V, 37G) and H-Ras(12V, 40C), which are defective for Raf binding and activation, induced potent tumorigenic transformation of some strains of NIH 3T3 fibroblasts. These Raf-binding defective mutants of H-Ras induced a transformed morphology that was indistinguishable from that induced by activated members of Rho family proteins. Furthermore, the transforming activities of both of these mutants were synergistically enhanced by activated Raf-1 and inhibited by the dominant negative RhoA(19N) mutant, indicating that Ras may cause transformation that occurs via coordinate activation of Raf-dependent and -independent pathways that involves Rho family proteins. Finally, cotransfection of H-Ras(12V, 37G) and H-Ras(12V, 40C) resulted in synergistic cooperation of their focus-forming activities, indicating that Ras activates at least two Raf-independent, Ras effector-mediated signaling events.

The influence of surgical operations on components of the human immune system

Surgical operations have been shown to cause a variety of immunological disturbances in man both in vivo and in vitro. With few exceptions the overall picture is one of a generalized state of immunodepression in the postoperative period. The implications of these observations are that host defences may be compromised by surgical procedures, thus providing a 'fertile soil' for bacterial invasion and tumour cell metastasis at the very time when risks from invading pathogens and viable tumour cells are maximal. We have studied the effects of surgical operations on the immune system in 35 patients with benign disease. Surgical procedures were classified as either minor (n = 15) or major (n = 20). A panel of monoclonal antibodies was used to identify peripheral blood lymphocyte subpopulations and analysis was performed using flow cytometry. Simultaneous estimations of plasma alpha-1 proteinase inhibitor (alpha-1-PI), alpha-2-macroglobulin (alpha-2-M), alpha-2-pregnancy-associated glycoprotein (alpha-2-PAG) and plasma suppressive activity (PSA) on stimulated allogeneic lymphocytes were performed before operation and on postoperative days 1, 3, 7, 17 and 21. Circulating numbers of all lymphocyte subpopulations fell significantly following surgery, except for B lymphocytes which did not change. The magnitude, and duration of the reduction in cell numbers and the subpopulation affected was significantly related to the degree of surgical trauma, and returned to pre-operative values by postoperative day 7. Changes in alpha-1-PI, alpha-2-M, alpha-2-PAG and PSA were also significantly related to the degree of surgical trauma, and these plasma changes persisted longer than the cellular disturbances. Surgical operations induce a reversible depression of cellular immunity which precedes plasma suppressive activity in its return to pre-operative levels. Immunostimulating agents such as interferon and the interleukins deserve evaluation as prophylactic agents pre-operatively.

Comparative hemodynamic, left ventricular functional, and antiadrenergic effects of chronic treatment with metoprolol versus carvedilol in the failing heart

BACKGROUND

The basic pharmacology of the third-generation beta-blocking agent carvedilol differs considerably from second-generation compounds such as metoprolol. Moreover, carvedilol may produce different, ie, more favorable, clinical effects in chronic heart failure. For these reasons, we compared the effects of carvedilol and metoprolol on adrenergic activity, receptor expression, degree of clinical beta-blockade, hemodynamics, and left ventricular function in patients with mild or moderate chronic heart failure.

METHODS AND RESULTS

The effects of carvedilol versus metoprolol were compared in two concurrent placebo-controlled trials with carvedilol or metoprolol that had common substudies focused on adrenergic, hemodynamic, and left ventricular functional measurements. All subjects in the substudies had chronic heart failure resulting from idiopathic dilated cardiomyopathy. Carvedilol at 50 to 100 mg/d produced reductions in exercise heart rate that were similar to metoprolol at 125 to 150 mg/d, indicating comparable degrees of beta-blockade. Compared with metoprolol, carvedilol was associated with greater improvement in New York Heart Association functional class. Although there were no significant differences in hemodynamic effects between the carvedilol and metoprolol active-treatment groups, carvedilol tended to produce relatively greater improvements in left ventricular ejection fraction, stroke volume, and stroke work compared with changes in the respective placebo groups. Carvedilol selectively lowered coronary sinus norepinephrine levels, an index of cardiac adrenergic activity, whereas metoprolol did not lower coronary sinus norepinephrine and actually increased central venous norepinephrine levels. Finally, metoprolol was associated with an increase in cardiac beta-receptor density, whereas carvedilol did not change cardiac beta-receptor expression.

CONCLUSIONS

The third-generation beta-blocking agent carvedilol has substantially different effects on left ventricular function, hemodynamics, adrenergic activity, and beta-receptor expression than dose the second-generation compound metoprolol. Some or all of these differences may explain the apparent differences in clinical results between the two compounds.

Receiving social support online: implications for health education

Online support groups are expanding as the general public becomes more comfortable using computer-mediated communication technology. These support groups have certain benefits for users who may not be able to or do not have the desire to attend face-to-face sessions. Online support groups also present challenges when compared to traditional face-to-face group communication. Communication difficulties may arise resulting from lack of visual and aural cues found in traditional face-to-face communication. Online support groups have emerged within health care as a result of the need individuals have to know more about health conditions they are confronting. The proliferation of these online communities may provide an opportunity for health educators to reach target populations with specific messages. This paper reviews the development of health-related online support groups, examines research conducted within these communities, compares their utility with traditional support groups and discusses the implications of these groups for health education.

Structure, expression, and T cell costimulatory activity of the murine homologue of the human B lymphocyte activation antigen B7

Following occupancy of the T cell receptor by antigen, T cell proliferation and lymphokine production are determined by a second costimulatory signal delivered by a ligand expressed on antigen presenting cells. The human B cell activation antigen B7, which is expressed on antigen presenting cells including activated B cells and gamma interferon treated monocytes, has been shown to deliver such a costimulatory signal upon attachment to its ligand on T cells, CD28. We have cloned and sequenced the murine homologue of the human B7 gene. The predicted murine protein has 44% amino acid identity with human B7. The greatest similarity is in the Ig-V and Ig-C like domains. Murine B7 mRNA was detected in murine hematopoietic cells of B cell but not T cell origin. Cells transfected with murine B7 provided a costimulatory signal to human CD28+ T lymphocytes. These results demonstrate the costimulatory activity of murine B7 and provide evidence that the ligand attachment site is conserved between the two species.

An IL-4 receptor region containing an insulin receptor motif is important for IL-4-mediated IRS-1 phosphorylation and cell growth

Interleukin-4 (IL-4) treatment of 32D cells overexpressing insulin receptor substrate 1 (IRS-1) causes prompt tyrosine phosphorylation of IRS-1. Transfection of truncation mutants of the human IL-4 (huIL-4) receptor into 32D-IRS-1 cells demonstrated that the region from amino acid 437-557 is important for IL-4 signaling. This region of the IL-4 receptor (IL-4R) contains the motif 488PL-X4-NPXYXSXSD502 (insulin/IL-4R [I4R]) found in the insulin and insulin-like growth factor 1 receptors. Mutation of Y497 to F yielded receptors that caused little or no IRS-1 phosphorylation in response to huIL-4 when expressed in 32D-IRS-1 cells. Most cell lines expressing Y497F also failed to proliferate in response to huIL-4. Furthermore, a glutathione-S-transferase fusion protein containing the I4R motif-bound IRS-1, tyrosine kinase(s), and other unidentified phosphoproteins with molecular sizes of 140, 80, and 55 kd. Thus, the central tyrosine of the I4R motif has a major role in IL-4-mediated signal transduction in 32D cells.

A constitutively active and nuclear form of the MAP kinase ERK2 is sufficient for neurite outgrowth and cell transformation

BACKGROUND

Mitogen-activated protein (MAP) kinases are ubiquitous components of many signal transduction pathways. Constitutively active variants have been isolated for every component of the extracellular-signal-regulated kinase 1 (ERK1) and ERK2 MAP kinase pathway except for the ERK itself.

RESULTS

To create an activated ERK2 variant, we fused ERK2 to the low activity form of its upstream regulator, the MAP kinase kinase MEK1. The ERK2 in this fusion protein was active in the absence of extracellular signals. Expression of the fusion protein in mammalian cells did not activate endogenous ERK1 or ERK2. It was sufficient, however, to induce activation of the transcription factors Elk-1 and AP-1, neurite extension in PC12 cells in the absence of nerve growth factor, and foci of morphologically and growth-transformed NIH3T3 cells, if the fusion protein was localized to the nucleus. A cytoplasmic fusion protein was without effect.

CONCLUSIONS

Activation of ERK2 is sufficient to cause several transcriptional and phenotypic responses in mammalian cells. Nuclear localization of activated ERK2 is required to induce these events.

Second malignancies after Ewing's sarcoma: radiation dose-dependency of secondary sarcomas

BACKGROUND

An excess risk of second malignancies has been reported in survivors of Ewing's sarcoma. We examined a multiinstitutional data base to reevaluate the risk among survivors of Ewing's sarcoma and to identify possible causal factors.

METHODS

Information was derived from a data base that included 266 survivors of Ewing's sarcoma. Cumulative incidence rates of second malignancies were calculated. Contributions of clinical features, type and dose of chemotherapy, and cumulative radiation dose to the risk of second malignancies were evaluated.

RESULTS

After a median follow-up duration of 9.5 years (range, 3.0 to 30), 16 patients have developed second malignancies, which included 10 sarcomas (five osteosarcomas, three fibrosarcomas, and two malignant fibrous histiocytomas) and six other malignancies (acute myeloblastic leukemia, acute lymphoblastic leukemia, meningioma, bronchioalveolar carcinoma, basal cell carcinoma, and carcinoma-in-situ of the cervix). The median latency to the diagnosis of the second malignancy was 7.6 years (range, 3.5 to 25.7). The estimated cumulative incidence rates at 20 years for any second malignancy and for secondary sarcoma were 9.2% (SD = 2.7%) and 6.5% (SD = 2.4%), respectively. The cumulative incidence rate of secondary sarcoma was radiation dose-dependent (P = .002). No secondary sarcomas developed among patients who had received less than 48 Gy, while the absolute risk of secondary sarcoma was 130 cases per 10,000 person-years of observation among patients who had received > or = 60 Gy.

CONCLUSION

The overall risk of second malignancies after Ewing's sarcomas is similar to that associated with treatment for other childhood cancers. The radiation dose-dependency of secondary sarcomas justifies modification in therapy to reduce radiation doses.