Back-mapping augmented adaptive resolution simulation

Concurrent multiscale techniques such as Adaptive Resolution Scheme (AdResS) can offer ample computational advantages over conventional atomistic (AT) molecular dynamics simulations. However, they typically rely on aphysical hybrid regions to maintain numerical stability when high-resolution degrees of freedom (DOFs) are randomly re-inserted at the resolution interface. We propose an Energy Minimized AT (DOF) Insertion (EMATI) method that uses an informed rather than random AT DOF insertion to tackle the root cause of the issue, i.e., overlapping AT potentials. EMATI enables us to directly couple AT and coarse-grained resolutions without any modifications of the interaction potentials. We exemplify AdResS-EMATI in a system of liquid butane and show that it yields improved structural and thermodynamic properties at the interface compared to competing AdResS approaches. Furthermore, our approach extends the applicability of the AdResS without a hybrid region to systems for which force capping is inadequate.

Abstract P3-01-23: Targeting of endocrine therapy-induced estrogen-receptor/HER2-cross-talk in circulating tumor cells from metastatic ER+/HER2- breast cancer: Implications for treatment of ER+/HER2- breast cancer

Background: Transient induction of HER2 expression upon inhibition of the estrogen-receptor (ERα) might be an underestimated rescue mechanism that enables ER+/HER2- breast cancer cells to survive and to grow in the presence of endocrine therapies. Besides protecting ER+/HER2- BC cells from endocrine treatment, transient HER2 expression is also considered to save circulating, disseminated and dormant ER+/HER2- BC cells from apoptotic cell death in hostile environments and might therefore be of importance for ER+ BC progression, metastasis formation and recurrence. Thus therapeutic strategies that efficiently target both ERα and HER2 simultaneously might improve treatment of patient with ER+/HER2- BCs.

Methods: Circulating tumor cells (CTCs) were originally isolated from a patient with bilateral ER+/HER2- metastatic BC. These cells have been treated with either the proteasome inhibitor (PI) carfilzomib or fulvestrant alone or with both drugs in combination. The consequences of these drugs upon ERα and HER2 expression were monitored by western blotting or qPCR. Induction of cell death upon treatment was measured by PARP and caspase cleavage or by quantification of SubG1 cells using propidium iodide staining or by the use of colony forming assays.

Results: Fulvestrant treatment of CTCs decreases the amount of ERα but immediately increases HER2 expression whereas carfilzomib markedly inhibits the expression of both ERα and HER2 simultaneously. Combined treatment of CTCs with carfilzomib + fulvestrant cause reduced expression of HER2 and lead to a much stronger decrease of ERα than carfilzomib or fulvestrant alone. Fulvestrant causes no significant reduction of proliferation and no induction of cell death. Conversely the combination of carfilzomib and fulvestrant causes a significant induction of apoptotic cell death and a massive reduction of colonies in colony forming assays.

Conclusion: These findings suggest that rapid and transient up-regulation of HER2 expression following endocrine treatment might be an important so far underestimated adaptive mechanism which enables ER+/HER2- BC cells to sustain proliferation in the presence of ERα-inhibitory drugs and to stay alive during the metastatic process. Furthermore these data also lead to the assumption that PIs such as carfilzomib in combination with ERα degraders could be a potential therapeutic strategy for efficient targeting of metastatic ER+/HER2- BC cells.

Citation Format: Thaler S, Roßwag S, Pantel K, Sleeman JP, Schmidt M, Cotarelo CL. Targeting of endocrine therapy-induced estrogen-receptor/HER2-cross-talk in circulating tumor cells from metastatic ER+/HER2- breast cancer: Implications for treatment of ER+/HER2- breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-23.

Seasonal forecasting of green water components and crop yield of summer crops in Serbia and Austria

A probabilistic crop forecast based on ensembles of crop model output estimates, presented here, offers an ensemble of possible realizations and probabilistic forecasts of green water components, crop yield and green water footprints (WFs) on seasonal scales for selected summer crops. The present paper presents results of an ongoing study related to the application of ensemble forecasting concepts in crop production. Seasonal forecasting of crop water use indicators (evapotranspiration (ET), water productivity, green WF) and yield of rainfed summer crops (maize, spring barley and sunflower), was performed using the AquaCrop model and ensemble weather forecast, provided by The European Centre for Medium-range Weather Forecast. The ensemble of estimates obtained was tested with observation-based simulations to assess the ability of seasonal weather forecasts to ensure that accuracy of the simulation results was the same as for those obtained using observed weather data. Best results are obtained for ensemble forecast for yield, ET, water productivity and green WF for sunflower in Novi Sad (Serbia) and maize in Groß-Enzersdorf (Austria) - average root mean square error (2006-2014) was <10% of observation-based values of selected variables. For variables yielding a probability distribution, capacity to reflect the distribution from which their outcomes will be drawn was tested using an Ignorance score. Average Ignorance score, for all locations, crops and variables varied from 1.49 (spring barley ET in Groß-Enzersdorf) to 3.35 (sunflower water productivity in Groß-Enzersdorf).

Abstract P5-10-01: Cellular senescence within HER2-amplified breast cancer: Potential implications for breast cancer immune surveillance and HER2-targeted therapy resistance

Background:Oncogene-induced senescence is considered as a barrier to tumor progression that arrests cells at risk for malignant transformation. Nevertheless, numerous findings demonstrate that senescent cells may also have the opposite function and promote tumor progression through the release of multiple factors called the senescence-associated secretory phenotype or senescence secretome. It is likely that the composition and the physiological consequences mediated by the senescence secretome are dependent on the oncogenes that trigger the senescence program. Breast cancer represents a heterogenous disease that can be divided into breast cancer subtypes caused by different subsets of genetic and epigenetic abnormalities. Therefore, tumor initiation and progression of breast cancer subtypes is triggered by variable oncogenic stimuli, and differences in the senescence secretomes within breast tumors might be responsible for tumor initiation, progression, metastasis and therapeutic response. Beside many studies concerning the role of senescence as a barrier to tumor progression using murine xenograft models very few investigations have been performed to elucidate how often senescent tumor cells appear within untreated human tumors, and if present whether these senescent tumor cells may play a role in disease progression, cancer immunosurveillance and therapy resistance.

Methode: In the present study we analysed the appearance of senescent cells within invasive human breast cancers from 129 untreated patients. Cellular senescence was detected by the use of SAβ-gal staining and by immunohistochemical detection of p16, p21, p53, Ki67 and lamin B1.

Results: Detection of cellular senescence by the use of SAβ-gal staining and detection of p16, p53, Ki67 and lamin B1 within invasive breast carcinomas indicate that senescent tumor cells varies strongly according to the breast cancer subtype. The highest percentages of senescent tumor cells exist within in the HER2-positive and luminal A breast carcinomas whereas no or very few senescent tumor cells were found in triple negative breast tumors. Based on these findings we suggest that the composition of secretomes released by senescent tumor cells from different breast cancer subtypes might be very distinct in respect to their ability to recruit immune cells, which can eliminate senescent tumor cells on one hand and regulate tumor growth, immune surveillance and therapy resistance on the other.

Conclusion: Further characterization of senescent secretomes from HER2 and other breast cancer subtypes and their potential role in tumor progression, immune surveillance and therapy response might be warranted for the understanding of cancer biology as well as prognostic and therapeutic applications.

Citation Format: Thaler S, Schad A, Kirkpatrick CJ, Sleeman JP, Springer E, Schmidt M, Cotarelo CL. Cellular senescence within HER2-amplified breast cancer: Potential implications for breast cancer immune surveillance and HER2-targeted therapy resistance [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-10-01.

Abstract P6-12-14: Proteasome inhibitors prevent bi-directional HER2/estrogen-receptor cross-talk leading to cell death in endocrine and lapatinib-resistant HER2+/ER+ breast cancer cells

Background:Aberrant signaling through HER2 and other members of the HER family has been identified as mediator of endocrine resistance in estrogen receptor alpha (ERα) positive breast cancer. On the other hand, ERα co-expression has been shown to attenuate the efficiency of anti-HER2 targeted therapies. These findings indicate that HER2 and ERα synergize to allow breast cancer cells to escape from both anti-ERα and anti-HER2-targeted therapies. Rationally designed clinical trials that combine endocrine therapy with anti-HER2 agents to interfere with HER2/ERα cross-talk have been conducted. However, the outcome of these trials suggests that novel therapeutic approaches are needed to further improve inhibition of HER2 and other HER family members in conjunction with a more efficient ERα blockade. We examined the ability of proteasome inhibitors (PIs) to disrupt HER2/ERα cross-talk in HER2+/ER+ breast cancer (BC) cells. Furthermore we investigated the potential of PIs to suppress the activity of a constitutively active HER2 variant resistant to trastuzumab and lapatinib.

Methode: HER2+/ER+ BC cells and fulvestrant resistant ER+ BC cells that overexpress a constitutively active HER2 variant resistant to trastuzumab and lapatinib have been treated with the PIs carfilzomib and bortezomib. The potential of these PIs to suppress ERα expression, to block HER2 activation and to inhibit the HER2 downstream pathways PI3K/Akt and Ras/MAPK was monitored by western blotting. Induction of cell death upon PI treatment was measured by quantification of SubG1 cells using propidium iodide staining or the use of colony formation assays.

Results: Carfilzomib and bortezomib markedly inhibit bi-directional HER2/ERα signaling pathways in HER2/ER+ BC cells. Both PIs suppress ERα expression, inhibit HER2 activity and subsequently suppress the HER2 downstream pathways PI3K/Akt and Ras/MAPK that are major executors for endocrine resistance. Furthermore we observed that both PIs stabilize the HER2 specific tyrosine phosphatase BDP1 (PTPN18), thereby suppressing the activity of even a constitutive active HER2 variant that cause resistance to trastuzumab and lapatinib. Based on these findings we hypothesize that PIs inhibits ERα and HER2 activity through different mechanisms as currently used therapeutic regiments.

Conclusion: These findings demonstrate that PIs disrupt the cross-talk between HER2 and ERα signaling pathways and therefore might have the potential to expand treatment opportunities for HER2+/ER+ and possibly also for other groups of BC patients.

Citation Format: Thaler S, Schmidt M, Thiede G, Schad A, Sleeman JP. Proteasome inhibitors prevent bi-directional HER2/estrogen-receptor cross-talk leading to cell death in endocrine and lapatinib-resistant HER2+/ER+ breast cancer cells [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-12-14.

In vivo biocompatibility of a new cyanine dye for ILM peeling

PURPOSE

To investigate the biocompatibility of the new cyanine dye: 3,3'-Di-(4-sulfobutyl)-1,1,1',1'-tetramethyl-di-1H-benz[e]indocarbocyanine (DSS) as a vital dye for intraocular application in an in vivo rat model and to evaluate the effects of this dye on retinal structure and function.

METHODS

DSS at a concentration of 0.5% was applied via intravitreal injections to adult Brown Norway rats with BSS serving as a control. Retinal toxicity was assessed 7 days later by means of retinal ganglion cell (RGC) counts, light microscopy, optical coherence tomography (OCT), and electroretinography (ERG).

RESULTS

No significant decrease in RGC numbers was observed. No structural changes of the central retina were observed either in vivo (OCT) or under light microscopy. ERGs detected a temporary reduction of retinal function 7 days after injection; this was no longer evident 14 days after injection.

CONCLUSIONS

DSS showed good biocompatibility in a well-established experimental in vivo setting and may be usable for intraocular surgery as an alternative to other cyanine dyes. In contrast to indocyanine green, it additionally offers fluorescence in the visual spectrum. Further studies with other animal models are needed before translation into clinical application.

[Using intracameral cefuroxime reduces postoperative endophthalmitis rate: 5 years experience at the University Eye Hospital Tübingen]

BACKGROUND

Cataract surgery is the most commonly performed surgical procedure in developed countries. The annual number of cataract surgeries in Germany is about 600,000. Acute postoperative endophthalmitis is a very severe and the most dreaded complication of cataract surgery. Various operative and non-operative measures have been suggested to prevent this serious complication. The European Society of Cataract & Refractive Surgeons (ESCRS) study of intracameral cefuroxime was the first prospective, randomised and partially placebo-controlled clinical trial showing the efficacy of antibiotic prophylaxis to prevent endophthalmitis in 2007. The aim of this retrospective study is to investigate a possible reduction of intracameral cefuroxime to prevent postoperative endophthalmitis at the University Eye Hospital Tübingen.

PATIENTS AND METHODS

During the period from January 2002 to August 2013, 2 time periods were determined based on the adoption of intracameral cefuroxime injections after cataract surgery. From January 2002 to May 2009 patients received at the end of cataract surgery a subconjunctival administration of 50 mg of mezlocillin and postoperative antibiotic eye drops (gentamicin) without intracameral injection. From June 2009 to August 2013, patients received an intracameral injection of cefuroxime while antibiotic drops (moxifloxacin) were used too. The rates of postoperative infectious endophthalmitis during these 2 periods were calculated.

RESULTS

31 cases of endophthalmitis occurred in 31,386 cataract surgeries. The overall cumulative incidence was 0.99 per 1000 patients. The incidence in the first period without intracameral cefuroxime injection was 1.38 (95 % confidence interval [CI]: 1.03-1.72) per 1000 patients and in the second period 0.44 (95 % CI: 0.34-0.54) per 1000 patients (p < 0.001).

CONCLUSION

Intracameral injection of cefuroxime reduces the rate of postoperative infectious endophthalmitis in cataract surgery significantly.

Considerations on methodological challenges for water footprint calculations

We have investigated how different approaches for water footprint (WF) calculations lead to different results, taking sugar beet production and sugar refining as examples. To a large extent, results obtained from any WF calculation are reflective of the method used and the assumptions made. Real irrigation data for 59 European sugar beet growing areas showed inadequate estimation of irrigation water when a widely used simple approach was used. The method resulted in an overestimation of blue water and an underestimation of green water usage. Dependent on the chosen (available) water quality standard, the final grey WF can differ up to a factor of 10 and more. We conclude that further development and standardisation of the WF is needed to reach comparable and reliable results. A special focus should be on standardisation of the grey WF methodology based on receiving water quality standards.

[Clinical results after cataract surgery in patients with Behçet's disease]

BACKGROUND

Behçet's disease is a systemic vasculitis disorder of unknown aetiology. Ocular involvement, especially with vasculitis, is detected in up to 80 % of the cases. Anterior segment involvement such as cataract is also seen in the follow-up of patients who are then treated surgically. In this study, we aimed to analyze the outcomes of cataract surgery in patients with Behçet's disease retrospectively.

PATIENTS AND METHODS

The records of 9 patients (12 eyes) with Behçet's disease who underwent phacoemulsification with IOL implantation in 11 eyes and extracapsular cataract extraction (ECCE) with IOL implantation in one eye between June 2001 and September 2009 were evaluated retrospectively. The visual outcome and complications were analysed.

RESULTS

The mean follow-up was 33.8 months (range 3 to 88 months). The mean preoperative LogMAR BCVA was 1.15 ± 0.53 (95 % CI: 0.81 - 1.49) and increased to 0.36 ± 0.32 (95 % CI: 0.15 - 0.56) at last medical visit (p < 0.001). The most frequent postoperative complication was posterior capsular opacification, which developed in 2 eyes (17 %). Other complications were mild fibrinous reaction in 1 eye (8 %).

CONCLUSIONS

The outcomes of cataract surgery in patients with Behçet's disease were satisfactory. The great majority of the patients regained and retained a good visual outcome and had fewer postoperative complications.

An in vivo evaluation of Brilliant Blue G in animals and humans

BACKGROUND/AIMS

To evaluate the retinal toxicity of Brilliant Blue G (BBG) following intravitreal injection in rat eyes and examine the biocompatibility and the staining properties in humans.

METHODS

BBG was injected into the 11 rat eyes to evaluate toxic effects with balanced salt solution (BSS) serving as control. Retinal toxicity was assessed by retinal ganglion cell (RGC) counts and by light microscopy 7 days later. In addition, BBG was applied during vitrectomy for macular hole (MH) (n = 15) or epiretinal membranes (ERM) (n = 3) in a prospective, non-comparative consecutive series of patients. Before and after surgery, all patients underwent a complete clinical examination including measurement of best corrected visual acuity (VA) and intraocular pressure, perimetry, fundus photography and optical coherence tomography. Patients were seen 1 day before surgery and then in approximately four weeks intervals.

RESULTS

No significant reduction in RGC numbers and no morphological alterations were noted. A sufficient staining of the internal limiting membrane (ILM) was seen in patients with MH, while the staining pattern in ERM cases was patchy, indicating that parts of the ILM were peeled off along with the ERM in a variable extent. All MHs could be closed successfully. VA improved in 10 eyes (56%; 8/15 MH patients, 2/3 ERM patients), was unchanged in four eyes (22%; all MH patients) and was reduced in four eyes (22%; 3/15 MH, 1/3 ERM). No toxic effects attributable to the dye were noted during patient follow-up. The ultrastructure of tissue harvested during surgery was unremarkable.

CONCLUSION

Brilliant Blue provides a sufficient and selective staining of the ILM. No retinal toxicity or adverse effects related to the dye were observed in animal and human studies. The long-term safety of this novel dye will have to be evaluated in larger patient series and a longer follow-up.

Staining and peeling of the internal limiting membrane using a fluorescent dye (Rhodamine 6 G)

AIM

To assess whether low concentrations of a fluorescent dye such as Rhodamine 6G would help the unaided human eye visualise the vitreous and the internal limiting membrane (ILM) under standard halogen illumination.

MATERIAL/METHODS

The UV/Vis absorption (E) and fluorescence (I) spectra of Rhodamine 6G in water were measured and compared with Indocyanine Green (ICG). Surgery was performed in two rhesus monkeys and consisted of standard pars plana vitrectomy with halogen light source used for illumination. Rhodamine 6G was diluted in balanced salt solution (BSS). A few drops of the dye in a concentration of 0.1% (307 mOsm) were applied over the posterior pole in the air-filled globe and washed out by irrigation after 1 min. Immediately after surgery, the globes were enucleated, fixated and prepared for histological evaluation.

RESULTS

In contrast to ICG, both the maximum of the absorption and emission of Rhodamin 6G are very much within the spectral sensitivity of the human eye. The Rhodamine 6G-BSS itself appears red in colour. Using a dye concentration of 0.1%, there was no visible red-staining of the ILM as such. As the dye was irrigated out with BSS, a marked green fluorescence of the fluid within the vitreous cavity was noted. With halogen illumination through a standard 20-gauge light pipe, the dye provided a sufficient green fluorescence to identify and safely remove the ILM and to clearly differentiate areas of peeled from non-peeled ILM. During light microscopy, eyes revealed a peeled ILM demarcation with no signs of acute retinal toxicity.

CONCLUSION

The findings indicate that a fluorescent dye can be used for ILM peeling. Assuming that the fluorophore provides a high enough fluorescence quantum yield after adsorption to the ILM, much lower dye concentrations could be used compared with absorbent dyes, thereby minimising toxic effects.

Inhibitors of apoptosis confer resistance to tumour suppression by adoptively transplanted cytotoxic T-lymphocytes in vitro and in vivo

Deregulation of apoptosis signalling is commonly found in cancer and results in resistance to cytotoxic therapies. Immunotherapy is a promising strategy to eliminate resistant cancer cells. The transfer of T-lymphocytes during allogeneic stem cell transplantation is clinically explored to induce a 'graft-versus-tumor' effect (GvT). Cytotoxic T-lymphocytes (CTL), which are major effectors of GvT, eliminate cancer cells by inducing apoptosis via multiple parallel pathways. Here, we study in vitro and in vivo the susceptibility of murine cancer cells engineered to express single antiapoptotic genes to CTL-mediated cytotoxicity. Interestingly, we find that single inhibitors of caspase activation, such as BCL-XL or dominant-negative mutants of FADD and caspase-9, protect cancer cells against antigen-specific CTL in vitro. Moreover, expression of BCL-XL impairs the growth suppression by adoptively transplanted CTL of established tumours in vivo. Hence, apoptosis defects that provide protection to cytotoxic cancer therapies can confer crossresistance to immunotherapy by tumour-reactive CTL.

A packaging cell line generating CD4-specific retroviral vectors for efficient gene transfer into primary human T-helper lymphocytes

Murine leukemia virus (MuLV) can be pseudotyped with a variant of the human immunodeficency virus (HIV) envelope gene encoding the surface glycoprotein gp120-SU and a carboxy-terminally truncated transmembrane (TM) protein with only seven cytoplasmic amino acids. MuLV/HIV-1 pseudotyped retroviral vectors selectively target gene transfer to human cells expressing both CD4 and CXCR4. To apply this vector system to gene therapy of human diseases, we generated a stable packaging cell line, FLY-HIV-87, expressing the MuLV gag and pol genes and the C-terminally truncated variant of the HIV-1 envelope gene, but no retroviral vector genome. Production of infectious vector particles was tested after the introduction of different vector genomes and was in the range of 5x10(5) IU/ml. The vector particles could be concentrated up to 25-fold. Specific and efficient gene transfer into CD4/CXCR4 expressing cell lines and stimulated primary human CD4+ peripheral blood lymphocytes was achieved. Thus the packaging cell line FLY-HIV-87 is highly suitable for gene therapy of disorders of human T-helper cells.

The Interdisciplinary Generalist Curriculum Project at the University of Wisconsin Medical School: the Generalist Partners Program

The Generalist Partners Program (GPP) provides all University of Wisconsin Medical School students with a comprehensive generalist core curriculum through early clinical experiences, interactive faculty presentations, and small-group discussions during the first two years of medical school. The GPP is the first component of a comprehensive, longitudinal generalist curriculum offered during all four years of medical education. Faculty members from family medicine, general internal medicine, and general pediatrics work together to develop the learning goals and provide the curriculum for the GPP courses. Each of the 145 entering first-year medical students is matched with a community-based physician, the generalist practice partner, and the students participate in early clinical experiences at this site throughout their first two years of medical education. Students' clinical experiences are presented and discussed in case-based small-group sessions led by the school's generalist faculty. A core lecture series on professionalism, communication skills, evidence-based medicine, and the organization of the health care system supplements the early clinical experiences.

Membrane-anchored peptide inhibits human immunodeficiency virus entry

Peptides derived from the heptad repeats of human immunodeficiency virus (HIV) gp41 envelope glycoprotein, such as T20, can efficiently inhibit HIV type 1 (HIV-1) entry. In this study, replication of HIV-1 was inhibited more than 100-fold in a T-helper cell line transduced with a retrovirus vector expressing membrane-anchored T20 on the cell surface. Inhibition was independent of coreceptor usage.

[Comparison of two different protocols on change of medication in central venous catheterization in patients with bone marrow transplantation: results of a randomized multicenter study]

Care of central venous catheter (CVC) in patients undergoing bone marrow transplantation (BMT) raises significant problems related to the high risk of local infections, to the immunodeficient status, which in itself is a predisposing factor for systematic blood stream infections. Although frequent changes of CVC dressing might theoretically reduce the incidence of infections, they are also accompanied by significant skin toxicity and patient discomfort. No study has yet addressed these points. The objective of this study was to compare two different time interval protocols for CVC dressing, in order to assess the effects on local infections and toxicity. In a multicentre study, 339 bone marrow transplant (BMT) patients with a tunnelled CVC (group A, 230 pts) or a non tunnelled one (Group B, 169 patients) were randomly allocated to receive CVC dressing changes every 5 or 10 days if belonging to group A or 2 or 5 days if in group B. Transparent impermeable polyurethane dressings were used for all patients. The rate of local infection at the site of CVC insertion was assessed by microbiological assay every 10 days, while severity of skin toxicity was measured according to the ECOG scale. Sixty-five per cent of enrolled patients were finally evaluable. Patients (in both groups) receiving CVC dressing changes at longer intervals did not show a significant increase in the rate of local infections, while those who received dressing every two days had a significant increase in local skin toxicity. Longer intervals were accompanied by a reduction in costs. The results of this study demonstrate that the increase in time interval between CVC dressing changes in BMT patients did not increment the risk of local infections, while significantly reducing patients discomfort and costs.

Comparison of two different time interval protocols for central venous catheter dressing in bone marrow transplant patients: results of a randomized, multicenter study. The Italian Nurse Bone Marrow Transplant Group (GITMO)

BACKGROUND AND OBJECTIVE

Care of central venous catheter (CVC) in patients undergoing bone marrow transplantation (BMT) raises significant problems related to the high risk of local infections due to the immunodeficient status, which in itself is a predisposing factor for systemic blood-stream infections. Although frequent changes of CVC dressing might theoretically reduce the incidence of infections, they are also accompanied by significant skin toxicity and patient discomfort. No study has yet addressed these points. The objective of this study was to compare two different time interval protocols for CVC dressing in order to assess the effects on local infections and toxicity.

DESIGN AND METHODS

In a multicenter study, 399 bone marrow transplant (BMT) patients with a tunneled CVC (Group A, 230 pts) or a non-tunneled one (Group B, 169 pts) were randomly allocated to receive CVC dressing changes every 5 or 10 days, if belonging to Group A, or 2 or 5 days, if in Group B. Transparent, impermeable polyurethane dressings were used for all patients. The rate of local infections at the site of CVC insertion was assessed by microbiological assays every 10 days, while the severity of skin toxicity was measured according to the ECOG scale.

RESULTS

Sixty-five per cent of enrolled patients were finally evaluable. Patients (in both Groups) receiving CVC dressing changes at longer intervals did not show a significant increase in the rate of local infections, while those who received dressing every 2 days had a significant increase in local skin toxicity. Longer intervals were accompanied by a reduction in costs.

INTERPRETATION AND CONCLUSIONS

The results of this study demonstrate that the increase in time interval between CVC dressing changes in BMT patients did not raise the risk of local infections, while significantly reducing patient discomfort and costs.

Truncation of the human immunodeficiency virus-type-2 envelope glycoprotein allows efficient pseudotyping of murine leukemia virus retroviral vector particles

The incorporation of human immunodeficiency virus-type-2 (HIV-2) envelope glycoprotein into murine leukemia virus (MuLV) particles was studied in a transient transfection packaging cell system. We observed that wild-type HIV-2 envelope protein or a frameshift mutant with 187 unrelated carboxyl-terminal residues did not allow the formation of infectious retroviral particles. In view of recent findings that an HIV-1 envelope protein variant with a shortened cytoplasmic domain was incorporated into MuLV particles, we constructed carboxyl-terminal truncations of the HIV-2 envelope protein. An envelope variant with 18 cytoplasmic amino acids formed only very few viral pseudotypes. The further removal of an additional 11 amino acids allowed the efficient pseudotyping of MuLV particles. As with the HIV-1 envelope protein, an HIV-2 envelope variant with 7 cytoplasmic amino acids was incorporated into functional MuLV particles. The pseudotyped vectors obtained are able to infect human CD4/CXCR4-expressing cells. Cell lines expressing human CD4 and other coreceptors could not be infected. This retroviral vector will prove useful for the study of HIV infection events mediated by the HIV-2 envelope glycoproteins, as well as for the targeting of CD4+ cells in the context of gene therapy of AIDS.

Suppression of smooth-muscle alpha-actin expression by platelet-derived growth factor in vascular smooth-muscle cells involves Ras and cytosolic phospholipase A2

Platelet-derived growth factor (PDGF), which is a potent mitogen for vascular smooth-muscle cells (VSMC), also inhibits the expression of specific smooth-muscle proteins, including smooth-muscle alpha-actin (SM-alpha-actin), in these cells. The goal of this study was to identify signalling pathways mediating these distinct effects. In rat aortic VSMC, PDGF caused a rapid activation of Ras and Raf, leading to the activation of mitogen-activated protein kinases (ERKs). Cells stably transfected with constitutively active Ras (H-Ras) expressed low levels of SM-alpha-actin protein. Arginine vasopressin, which stimulated SM-alpha-actin promoter activity in wild-type cells or controls (Neo; transfected with a plasmid lacking an insert), failed to do so in cells transiently expressing H-Ras. The effects of Ras on suppression of SM-alpha-actin expression were not mediated by the Raf/ERK pathway, since cells stably expressing constitutively active Raf (BxB-Raf) had normal levels of SM-alpha-actin protein, and stimulation of SM-alpha-actin promoter activity by vasopressin was unaffected in cells transiently expressing BxB-Raf. Furthermore a specific inhibitor of ERK activation had no effect on SM-alpha-actin expression. Exposure of wild-type VSMC to PDGF, or stable expression of Ras but not Raf, also resulted in constitutive increases in prostaglandin E2 production and cytosolic phospholipase A2 (cPLA2) activity, which was mediated by an increased expression of cPLA2 protein. Transient expression of cPLA2 in wild-type VSMC inhibited the stimulation of SM-alpha-actin promoter activity by vasopressin. These results suggest that PDGF-induced inhibition of SM-alpha-actin expression is mediated through a Ras-dependent/Raf independent pathway involving the induction of cPLA2 and eicosanoid production.

Induction of cytosolic phospholipase A2 by oncogenic Ras in human non-small cell lung cancer

Mutations in Ras family members that confer oncogenic potential are frequently observed in specific human cancers. We report that human non-small cell lung cancer (NSCLC) lines that harbor oncogenic mutations in Ki-Ras (H460, A549, H2122) synthesized high levels of prostaglandin E2 (PGE2) compared with NSCLC lacking Ras mutations or non-transformed lung epithelial cells (BEAS-2B). This increased PGE2 production was mediated by constitutively high expression of 85-kDa cytosolic phospholipase A2 (cPLA2) and cyclooxygenase 2 (COX-2). The increased expression of cPLA2 protein was mediated through elevated mRNA levels and activation of the cPLA2 promoter. Induction of cPLA2 promoter activity was blocked by expression of dominant-negative forms of Ras. Inhibition of Ras by the farnesyltransferase inhibitor BZA-5B inhibited prostaglandin synthesis in H2122 cells by decreasing expression of both cPLA2 and COX-2. Finally, inhibitors of eicosanoid synthesis blocked anchorage-independent growth of NSCLC lines exhibiting Ki-Ras mutations. These results identify cPLA2 as a novel Ras-inducible regulator of eicosanoid synthesis that participates in cellular transformation.

Effect of electromagnetic stimulation with different waveforms on cultured chick tendon fibroblasts

An energy efficient electromagnetic stimulator device for fracture healing was compared to a commercially available device in stimulating cell growth in tissue cultures. The energy efficient device, which conserves energy by using a bidirectional time-dependent magnetic wave form, and the commercially available stimulator, which uses a unidirectional time-dependent magnetic wave form, were tested on chick tendon fibroblasts in primary culture. Comparing non-stimulated control and cells electromagnetically stimulated with unidirectional and bidirectional waveforms showed that at the growth phase between days 2 and 3, both electrical stimulation techniques increased cell division as measured by DNA synthesis. When cells were dividing rapidly, collagen synthesis was reduced. When the cells reached the confluence there was no difference among the groups (control, unidirectionally stimulated, and bidirectionally stimulated) in terms of number of cells or collagen produced.

A portable pulsed electromagnetic field (PEMF) device to enhance healing of recalcitrant venous ulcers: a double-blind, placebo-controlled clinical trial

A prospective, randomized, double-blind, placebo-controlled multicentre study assessed the clinical efficacy and safety of pulsed electromagnetic limb ulcer therapy (PELUT) in the healing of recalcitrant, predominantly venous leg ulcers. The portable device was used at home for 3 h daily during this 8-week clinical trial as an adjunct to a wound dressing. Wound surface area, ulcer depth and pain intensity were assessed at weeks 0, 4 and 8. At week 8 the active group had a 47.7% decrease in wound surface area vs. a 42.3% increase for placebo (P < 0.0002). Investigators' global evaluations indicated that 50% of the ulcers in the active group healed or markedly improved vs. 0% in the placebo group, and 0% of the active group worsened vs. 54% of the placebo group (P < 0.001). Significant decreases in wound depth (P < 0.04) and pain intensity (P < 0.04) favouring the active group were seen. Patients whose ulcers improved significantly after 8 weeks were permitted to continue double-blind therapy for an additional 4 weeks. Eleven active and one placebo patient continued therapy until week 12, with the active treatment group continuing to show improvement. There were no reports of adverse events attributable to this device. We conclude that the PELUT device is a safe and effective adjunct to non-surgical therapy for recalcitrant venous leg ulcers.

Delayed hypersensitivity and local control of patients treated by radiotherapy for head and neck cancer

Delayed hypersensitivity of sixty-three patients with head and neck cancer treated by radiotherapy was correlated with short-term tumor control. Of eighteen patients with early disease, sixteen were DNCB-reactive and all were controlled and one of the two nonreactors was controlled. Thirty-three of forty-five patients with advanced tumors were reactive and nineteen were controlled. Only two of the twelve nonreactors were controlled.

Hepatoma induced by thorium dioxide

A 74-year-old man complained of anorexia and weight loss. Twenty-six years earlier he had received an injection of Thorotrast. A needle biopsy of the liver showed thorium dioxide granules and periportal fibrosis. On laparotomy, a hepatoma of the left lobe of the liver was discovered. Hepatic malignancy should be suspected in any patient with abnormal results of liver function tests, particularly an elevated level of alkaline phosphatase, who previously has had an injection of Thorotrast.