Applicability of radiomics in interstitial lung disease associated with systemic sclerosis: proof of concept.

OBJECTIVE: To retrospectively evaluate if texture-based radiomics features are able to detect interstitial lung disease (ILD) and to distinguish between the different disease stages in patients with systemic sclerosis (SSc) in comparison with mere visual analysis of high-resolution computed tomography (HRCT). METHODS: Sixty patients (46 females, median age 56 years) with SSc who underwent HRCT of the thorax were retrospectively analyzed. Visual analysis was performed by two radiologists for the presence of ILD features. Gender, age, and pulmonary function (GAP) stage was calculated from clinical data (gender, age, pulmonary function test). Data augmentation was performed and the balanced dataset was split into a training (70%) and a testing dataset (30%). For selecting variables that allow classification of the GAP stage, single and multiple logistic regression models were fitted and compared by using the Akaike information criterion (AIC). Diagnostic accuracy was evaluated from the area under the curve (AUC) from receiver operating characteristic (ROC) analyses, and diagnostic sensitivity and specificity were calculated. RESULTS: Values for some radiomics features were significantly lower (p < 0.05) and those of other radiomics features were significantly higher (p = 0.001) in patients with GAP2 compared with those in patients with GAP1. The combination of two specific radiomics features in a multivariable model resulted in the lowest AIC of 10.73 with an AUC of 0.96, 84% sensitivity, and 99% specificity. Visual assessment of fibrosis was inferior in predicting individual GAP stages (AUC 0.86; 83% sensitivity; 74% specificity). CONCLUSION: The correlation of radiomics with GAP stage, but not with the visually defined features of ILD-HRCT, implies that radiomics might capture features indicating severity of SSc-ILD on HRCT, which are not recognized by visual analysis. KEY POINTS: • Radiomics features can predict GAP stage with a sensitivity of 84% and a specificity of almost 100%. • Extent of fibrosis on HRCT and a combined model of different visual HRCT-ILD features perform worse in predicting GAP stage. • The correlation of radiomics with GAP stage, but not with the visually defined features of ILD-HRCT, implies that radiomics might capture features on HRCT, which are not recognized by visual analysis.

Evaluation of Intraoperative, Local Site Injections of Liposomal Bupivacaine as an Alternative to Standard Local Anesthetics in Patients Undergoing Total Hip Arthroplasty.

Background: Achieving postsurgical pain control after total hip arthroplasty (THA) is a critical factor for successful recovery because inadequately treated pain may lead to a delay in ambulation and hospital discharge and have an adverse impact on a patient's quality of life. Objective: This study compares the effectiveness of immediate-release local anesthetics for pain control in THA vs liposomal bupivacaine (LB) related to patient outcomes and costs of care. Methods: This is a retrospective cohort study of consecutive patients undergoing THA at 3 hospitals from January 2013 to July 2016. The control group received plain bupivacaine or ropivacaine while the study group received LB. Generalized linear models were used controlling for several patient factors. Primary measures included length of stay (LOS), hospitalization costs, pain relief, opioid use, and mobility. Secondary outcomes were discharge disposition and 30-, 60-, and 90-day readmissions. Results: One hundred and ninety-six patients were identified, with 103 as controls, 70 receiving LB, and 23 excluded. The LB group showed a decrease in LOS of 0.5 days (2.5 ± 2.6 vs 3.0 ± 2.1 days, P = .010), increased mobility on the day of surgery (27.6 ± 49.3 vs 12.5 ± 48.5 feet, P = .001) and the first day after surgery (186.8 ± 133.8 vs 155.2 ± 135.6, P = .039), and decreased hospital costs ($10 670 vs $11 351, P = .022). There were no significant differences in pain scores, opioid use, adverse events, discharge disposition, or readmissions. Study limitations include retrospective analysis, unblinded participants, and generalizability of results. Conclusions: LB provides an effective alternative to standard local anesthetics in patients undergoing THA based on improvements of inpatient parameters, LOS, and cost measures.

[Systemic sclerosis-clinical picture, diagnosis, and treatment]. / Systemische Sklerose ­ klinisches Bild, Diagnostik und Therapie.

Systemic sclerosis is a rare rheumatologic disease that is characterised by skin and organ fibrosis as well as vascular changes and the occurrence of specific autoantibodies. It has a high morbidity and mortality while its manifestations show significant heterogeneity in patients. Thus, diagnosis and follow-up of patients with systemic sclerosis has to be extensive, the more so because treatment must be adapted to organ manifestations. Although specific therapies for gastrointestinal, pulmonary or vascular complications exist, patients respond only partly to these and new therapeutic approaches are still needed.

[Systemic sclerosis-clinical picture, diagnosis, and treatment]. / Systemische Sklerose ­ klinisches Bild, Diagnostik und Therapie.

Systemic sclerosis is a rare rheumatologic disease that is characterised by skin and organ fibrosis as well as vascular changes and the occurrence of specific autoantibodies. It has a high morbidity and mortality while its manifestations show significant heterogeneity in patients. Thus, diagnosis and follow-up of patients with systemic sclerosis has to be extensive, the more so because treatment must adapted to organ manifestations. Although specific therapies for gastrointestinal, pulmonary or vascular complications exist, patients respond only partly to these and new therapeutic approaches are still needed.

Quantifying the influence of size, shape, and density of microplastics on their transport modes: A modeling approach.

Microplastics (MPs) pose significant risks to marine ecosystems and human health, necessitating accurate predictions of their distributions in aquatic environments for effective risk mitigation. However, understanding MP transport dynamics is challenging because of the inadequate representation of MP characteristics such as size, shape, and density in numerical models. Further, the accuracy of the MP vertical profiles in existing models has not been thoroughly validated. Thus, we developed an MP transport model within the Finite Volume Community Ocean Model framework (FVCOM-MP) by integrating MP characteristics. We validated FVCOM-MP against experimental and analytical data, focusing on various MP transport modes and transitions. FVCOM-MP successfully replicates MP profiles in different transport modes, including the bedload, surface load, suspended load, and mixed load modes. Additionally, we introduce phase diagrams for classifying MP transport modes based on particle characteristics, enhancing our understanding of MP dynamics in aquatic systems. The transport modes for a number of real-world MP particles, including fishing line, plastic bag/bottle fragments, synthetic fibers, tire wear particles, polyvinyl chloride and expanded polystyrene pellets, were analyzed with these phase diagrams.

[Early symptoms of dermatomyositis and antisynthetase syndrome]. / Frühsymptome der Dermatomyositis und des Antisynthetase-Syndroms.

INTRODUCTION: The early diagnosis of rheumatic diseases is becoming increasingly important. This particularly includes inflammatory myopathies which are multisystemic disorders with visceral involvement that are associated with high morbidity and mortality. Early diagnosis before the development of irreversible organ involvement is, therefore, of great importance. METHODS: This report provides information on early signs and symptoms of dermatomyositis and antisynthetase syndrome. Furthermore, screening methods which allow early diagnosis including involvement of internal organs are discussed. In addition, clinical and serological subtypes and their impact on prognosis are described.

Serum metabolites as biomarkers in systemic sclerosis-associated interstitial lung disease.

Systemic sclerosis (SSc) is a severe multi-organ disease with interstitial lung disease (ILD) being the major cause of death. While targeted therapies are emerging, biomarkers for sub-stratifying patients based on individual profiles are lacking. Herein, we investigated how levels of serum metabolites correlated with different stages of SSc and SSc-ILD. Serum samples of patients with SSc without ILD, stable and progressive SSc-ILD as well as of healthy controls (HC) were analysed using liquid targeted tandem mass spectrometry. The best discriminating profile consisted of 4 amino acids (AA) and 3 purine metabolites. L-tyrosine, L-tryptophan, and 1-methyl-adenosine distinguished HC from SSc patients. L-leucine, L-isoleucine, xanthosine, and adenosine monophosphate differentiated between progressing and stable SSc-ILD. In SSc-ILD, both, L-leucine and xanthosine negatively correlated with changes in FVC% predicted. Additionally, xanthosine was negatively correlated with changes in DLco% predicted and positively with the prognostic GAP index. Validation of L-leucine and L-isoleucine by an enzymatic assay confirmed both the sub-stratification of SSc-ILD patients and correlation with lung function and prognosis score. Serum metabolites may have potential as biomarkers for discriminating SSc patients based on the presence and severity of ILD. Confirmation in larger cohorts will be needed to appreciate their value for routine clinical care.

Use of vasoactive/vasodilating drugs for systemic sclerosis (SSc)-related digital ulcers (DUs) in expert tertiary centres: results from the analysis of the observational real-life DeSScipher study.

INTRODUCTION: DeSScipher is the first European multicentre study on management of systemic sclerosis (SSc), and its observational trial 1 (OT1) evaluated the efficacy of different drugs for digital ulcer (DU) prevention and healing. The aim of this study was to assess current use of vasoactive/vasodilating agents for SSc-related DU in the expert centres by analysing the baseline data of the DeSScipher OT1. METHOD: Baseline characteristics of patients enrolled in the OT1 and data regarding DU were analysed. RESULTS: The most commonly used drugs, in both patients with and without DU, were calcium channel blockers (CCBs) (71.6%), followed by intravenous iloprost (20.8%), endothelin receptor antagonists (ERAs) (20.4%) and phosphodiesterase 5 (PDE-5) inhibitors (16.5%). Of patients, 32.6% with DU and 12.8% without DU received two drugs (p < 0.001), while 11.5% with DU and 1.9% without DU were treated with a combination of three or more agents (p < 0.001). Sixty-five percent of the patients with recurrent DU were treated with bosentan and/or sildenafil. However, 64 out of 277 patients with current DU (23.1%) and 101 (23.6%) patients with recurrent DU were on CCBs alone. CONCLUSIONS: Our study shows that CCBs are still the most commonly used agents for DU management in SSc. The proportion of patients on combination therapy was low, even in patients with recurrent DU: almost one out of four patients with current and recurrent DU was on CCBs alone. Prospective analysis is planned to investigate the efficacy of different drugs/drug combinations on DU healing and prevention. Key Points • The analysis of DeSScipher, the first European multicentre study on management of SSc, has shown that the most commonly used vasoactive/vasodilating drugs for DU were CCBs, followed by intravenous Iloprost, ERAs and PDE-5 inhibitors. • More than half of the patients with recurrent DU received bosentan and/or sildenafil. • However, the proportion of patients on combination therapy of more than one vasoactive/vasodilating drug was low and almost one out of four patients with current and recurrent DU was on CCBs alone.

Macroecology: the division of food and space among species on continents.

Analyses of statistical distributions of body mass, population density, and size and shape of geographic range offer insights into the empirical patterns and causal mechanisms that characterize the allocation of food and space among the diverse species in continental biotas. These analyses also provide evidence of the processes that couple ecological phenomena that occur on disparate spatial and temporal scales-from the activities of individual organisms within local populations to the dynamics of continent-wide speciation, colonization, and extinction events.

Measurements of the diameters of the great arteries and semi-lunar valves of chick and mouse embryos.

The great arteries of embryos are small channels of a complex three-dimensional arrangement. Measurements of their diameters, as required for understanding cardiovascular morphogenesis and the genesis of malformations, cannot be performed in two-dimensional histological sections. We present and evaluate a quick and simple method for performing highly significant and objective measurements of the diameters of blood vessels in vertebrate embryos and used this method for providing statistics of the diameter of the semi-lunar valves and the lumina of the great arteries of early chick and mouse foetus. We employed the high-resolution episcopic microscopy technique for generating volume data and three-dimensional computer models of the arterial trees of 30 chick embryos (Hamburger Hamilton stage 34), 30 mouse embryos of the OF1 strain harvested on 14.5 dpc, 30 embryos of the OF1 strain harvested on 15.5 dpc and 28 mouse embryos of the PARKES strain harvested on 14.5 dpc. The three-dimensional models (voxel size 2 mum x 2 mum x 2 mum and 3 mum x 3 mum x 3 mum) were used for defining virtual resection planes perpendicular to the longitudinal axis of the blood vessels at comparable positions. In these planes, we measured the lumen areas and the lumen perimeters. We also calculated the lumen diameter and the true lumen area from the perimeter and present statistical analysis. Finally, we evaluate and discuss the reliability and reproducibility of our method and present all measurements in a form that minimizes the influence of specimen size variation, specimen processing and data generation methods.

[Systemic sclerosis. Objectives for the treatment]. / Systemische Sklerose. Zielkriterien der Behandlung.

Systemic sclerosis (SSc) is a multi-systemic fibrotic disorder with worldwide distribution and high morbidity and mortality. Characteristic features of this disease are widespread vasculopathy, inflammation, autoimmunity, and fibrosis. The better clinical outcome in recent years is mainly due to better management of organ complications. To date, there is no approved specific therapy to prevent or slow down the overall progression of the disease. So far, conventional disease-modifying antirheumatic drugs (DMARDs) have had no major impact on the disease course and have not prolonged survival. Based on recent studies of molecular pathomechanisms and various animal models, key molecules of fibrogenesis and vasculopathy in SSc could be identified. Therefore, to date, we have to reconsider and redefine the objectives of our treatment strategies. In this article, we discuss current and future therapeutic concepts as well as the objectives of new treatment strategies and of the evaluation of diagnostic tools with respect to pulmonary arterial hypertension, lung fibrosis and skin/systemic fibrosis.

Classification, categorization and essential items for digital ulcer evaluation in systemic sclerosis: a DeSScipher/European Scleroderma Trials and Research group (EUSTAR) survey.

BACKGROUND: A consensus on digital ulcer (DU) definition in systemic sclerosis (SSc) has been recently reached (Suliman et al., J Scleroderma Relat Disord 2:115-20, 2017), while for their evaluation, classification and categorisation, it is still missing. The aims of this study were to identify a set of essential items for digital ulcer (DU) evaluation, to assess if the existing DU classification was useful and feasible in clinical practice and to investigate if the new categorisation was preferred to the simple distinction of DU in recurrent and not recurrent, in patients with systemic sclerosis (SSc). METHODS: DeSScipher is the largest European multicentre study on SSc. It consists of five observational trials (OTs), and one of them, OT1, is focused on DU management. The DeSScipher OT1 items on DU that reached ≥ 60% of completion rate were administered to EUSTAR (European Scleroderma Trials and Research group) centres via online survey. Questions about feasibility and usefulness of the existing DU classification (DU due to digital pitting scars, to loss of tissue, derived from calcinosis and gangrene) and newly proposed categorisation (episodic, recurrent and chronic) were also asked. RESULTS: A total of 84/148 (56.8%) EUSTAR centres completed the questionnaire. DeSScipher items scored by ≥ 70% of the participants as essential and feasible for DU evaluation were the number of DU defined as a loss of tissue (level of agreement 92%), recurrent DU (84%) and number of new DU (74%). For 65% of the centres, the proposed classification of DU was considered useful and feasible in clinical practice. Moreover, 80% of the centres preferred the categorisation of DU in episodic, recurrent and chronic to simple distinction in recurrent/not recurrent DU. CONCLUSIONS: For clinical practice, EUSTAR centres identified only three essential items for DU evaluation and considered the proposed classification and categorisation as useful and feasible. The set of items needs to be validated while further implementation of DU classification and categorisation is warranted. TRIAL REGISTRATION: Observational trial on DU (OT1) is one of the five trials of the DeSScipher project (ClinicalTrials.gov; OT1 Identifier: NCT01836263 , posted on April 19, 2013).

Actionable perturbations of damage responses by TCL1/ATM and epigenetic lesions form the basis of T-PLL.

T-cell prolymphocytic leukemia (T-PLL) is a rare and poor-prognostic mature T-cell malignancy. Here we integrated large-scale profiling data of alterations in gene expression, allelic copy number (CN), and nucleotide sequences in 111 well-characterized patients. Besides prominent signatures of T-cell activation and prevalent clonal variants, we also identify novel hot-spots for CN variability, fusion molecules, alternative transcripts, and progression-associated dynamics. The overall lesional spectrum of T-PLL is mainly annotated to axes of DNA damage responses, T-cell receptor/cytokine signaling, and histone modulation. We formulate a multi-dimensional model of T-PLL pathogenesis centered around a unique combination of TCL1 overexpression with damaging ATM aberrations as initiating core lesions. The effects imposed by TCL1 cooperate with compromised ATM toward a leukemogenic phenotype of impaired DNA damage processing. Dysfunctional ATM appears inefficient in alleviating elevated redox burdens and telomere attrition and in evoking a p53-dependent apoptotic response to genotoxic insults. As non-genotoxic strategies, synergistic combinations of p53 reactivators and deacetylase inhibitors reinstate such cell death execution.

Nucleotide sequence analysis of a cloned DNA fragment from human cells reveals homology to retrotransposons.

During molecular cloning of proviral DNA of human spumaretrovirus, various recombinant clones were established and analyzed. Blot hybridization revealed that one of the recombinant plasmids had the characteristic features of a member of the long interspersed repetitive sequences family. The DNA element was analyzed by restriction mapping and nucleotide sequencing. It showed a high degree of amino acid sequence homology of 54.3% when compared with the 5'-terminal part of the pol gene product of the murine retrotransposon LIMd. The 3' region of the cloned DNA element encodes proteins with an even higher degree of homology of 67.4% in comparison to the corresponding parts of a member of the primate KpnI sequence family.

[Killing of cattle via electrical stunning]. / Töten von Rindern mittels Strom.

For disease control in the case of epidemics killing of cattle via electrical stunning is a method of choice. The official veterinarian is responsible for monitoring the adhesion to animal welfare principles during electrical stunning and killing. This requires specialised knowledge and experience as the symptoms of effective stunning are quite variable in cattle. Signs of effective and ineffective stunning are described below. In addition to suitable technical equipment, restraint of the animals and correct use of the equipment, neurophysiological processes have to be considered. Calm handling of the animals avoiding stress is a prerequisite for ensuring animal welfare and minimising pain especially when killing cattle using electrical methods.

Synergistic cytotoxicity in solid tumor cell lines between N-(4-hydroxyphenyl)retinamide and modulators of ceramide metabolism.

BACKGROUND: We previously reported that N-(4-hydroxyphenyl)retinamide (4-HPR, fenretinide) treatment caused large increases of ceramide levels in neuroblastoma cell lines and induced cell death by a combination of apoptosis and necrosis through p53 (also known as TP53)-independent and caspase-independent pathways. Our goal was to determine if several molecules that inhibit enzymes involved in ceramide metabolism-L-threo-dihydrosphingosine (safingol), d, l-threo-1-phenyl-2-hexadecanoylamino-3-morpholino-1-propanol (PPMP), and tamoxifen-enhanced 4-HPR-mediated cytotoxicity and/or affected ceramide levels. METHODS: Cellular lipids were quantified by radiolabeling and thin-layer chromatography. Cytotoxicity and cytotoxic synergy (expressed as combination index, where combination index <1 indicates synergy and >1 indicates antagonism) were measured in cultured cancer cell lines with the use of a fluorescence-based assay of cell viability employing digital imaging microscopy. Statistical tests were two-sided. RESULTS: 4-HPR increased ceramide levels by de novo synthesis. Safingol (1-4 microM) was incorporated into a stereochemical variant of ceramide and synergized with a 3:1 molar ratio of 4-HPR (3-12 microM), to produce a 100-fold to 10 000-fold (2 to 4 logs) increase in cytotoxicity relative to 4-HPR alone in neuroblastoma (combination index <0.1), lung (combination index <0.1-0.2), melanoma (combination index <0.1-0.2), prostate (combination index <0.1-1.0), colon (combination index 0.1-0.3), breast (combination index = 0.1-0.5), and pancreas (combination index = 0.2) cell lines, including p53 mutant and alkylator-resistant cell lines. The 4-HPR and safingol combination was cytotoxic in low-oxygen conditions and was minimally toxic to normal fibroblasts and bone marrow myeloid progenitor cells. Addition of agents that retard ceramide glucosylation and/or acylation, such as PPMP or tamoxifen, to 4-HPR or to the combination of 4-HPR and safingol further increased cytotoxicity to tumor cells. CONCLUSIONS: Combinations of 4-HPR and modulators of ceramide metabolism may form the basis for a novel chemotherapy that is functional under hypoxic conditions (e.g., such as those within tumors) and is p53 independent and caspase independent.

Increase of ceramide and induction of mixed apoptosis/necrosis by N-(4-hydroxyphenyl)- retinamide in neuroblastoma cell lines.

BACKGROUND: The synthetic retinoid N-(4-hydroxyphenyl)retinamide (4-HPR or fenretinide) is toxic to myeloid leukemia and cervical carcinoma cell lines, probably in part due to its ability to increase levels of reactive oxygen species (ROS). We have studied the effects of 4-HPR on neuroblastoma cell lines. Since neuroblastomas commonly relapse in bone marrow, a hypoxic tissue compartment, and many chemotherapeutic agents are antagonized by hypoxia, our purpose was to study in these cell lines several factors influencing 4-HPR-induced cytotoxicity, including induced levels of ROS, effects of physiologic hypoxia and antioxidants, levels of ceramide, and the mechanism of cell death. METHODS: ROS generation was measured by carboxydichlorofluorescein diacetate fluoresence. Ceramide was quantified by radiolabeling and thin-layer chromatography. Immunoblotting was used to assess p53 protein levels. Apoptosis (programmed cell death) and necrosis were analyzed by nuclear morphology and internucleosomal DNA fragmentation patterns. Cytotoxicity was measured by a fluorescence-based assay employing digital imaging microscopy in the presence or absence of the pancaspase enzyme inhibitor BOC-d-fmk. Statistical tests were two-sided. RESULTS/CONCLUSIONS: In addition to increasing ROS, 4-HPR (2.5-10 microM) statistically significantly increased the level of intracellular ceramide (up to approximately 10-fold; P<.001) in a dose-dependent manner in two neuroblastoma cell lines, one of which is highly resistant to alkylating agents and to etoposide. Cell death induced by 4-HPR was reduced but not abrogated by hypoxia in the presence or absence of an antioxidant, N-acetyl-L-cysteine. Expression of p53 protein was not affected by 4-HPR. Furthermore, the pan-caspase enzyme inhibitor BOC-d-fmk prevented apoptosis, but not necrosis, and only partially decreased cytotoxicity induced by 4-HPR, indicating that 4-HPR induced both apoptosis and necrosis in neuroblastoma cells. IMPLICATIONS: 4-HPR may form the basis for a novel, p53-independent chemotherapy that operates through increased intracellular levels of ceramide and that retains cytotoxicity under reduced oxygen conditions.

Cell-mediated immunity in mice against papain-solubilized histocompatibility and tumor-specific antigens by a macrophage migration inhibition microassay.

The cell-mediated immune status of B10.D2 (H-2d) mice immunized with spleen cells from a congenic strain, B10.A (H-2a), differing at the H-2 locus and of BALB/c mice immunized with a syngeneic simian virus 40 (SV40)-induced sarcoma (mKSA-TU5) was evaluated by an agarose microassay for migration inhibition factor. The inducing antigens in this experiment were papain-solubilized and partially purified chromatographic preparations of spleen cells from A/J mice (H-2a) and a papain-solubilized antigen extract prepared from a tissue culture-adapted cell line (TU-5), derived from the SV40-induced mKSA tumor. The assay used microliters of normal or immune peritoneal exudate cells (PEC) resuspended in a 2-mul droplet of agarose and cultured in the presence or absence of antigen. Specific migration inhibition of PEC from immunized mice was observed with concentrations of solubilized antigen preparations as low as 2.0 mug/ml (3.67 mug/chamber).

N-(4-hydroxyphenyl)retinamide elevates ceramide in neuroblastoma cell lines by coordinate activation of serine palmitoyltransferase and ceramide synthase.

The retinoid N-(4-hydroxyphenyl)retinamide (4-HPR; fenretinide) is cytotoxic to a variety of cancer cell lines, and we previously showed an association between ceramide generation and 4-HPR cytotoxicity for neuroblastoma cell lines (B. J. Maurer et al., J. Natl. Cancer Inst. (Bethesda), 91: 1138-1146, 1999). Here we determine whether the increased ceramide mediated by 4-HPR in the CHLA-90 human neuroblastoma cell line results from de novo ceramide synthesis. Treatment of CHLA-90 with 4-HPR for 2 h, in the presence of [(3)H]palmitic acid, caused sequential formation of [(3)H]sphinganine (220% over control) and [(3)H]ceramide (160% over control), with sphinganine returning to baseline at 4 h, and ceramide continuing to increase (215% over control). 4-HPR treatment did not accelerate cellular decay of sphingomyelin. Preincubation of cells with either L-cycloserine, an inhibitor of serine palmitoyltransferase (SPT), or fumonisin B(1), an inhibitor of ceramide synthase, retarded ceramide formation in response to 4-HPR treatment, although sphinganine was still generated when 4-HPR and FB(1) were present. Data from in vitro enzyme assays using microsomes showed that preexposure of intact cells to 4-HPR resulted in a time (175% over control; 6 h)- and dose-dependent increase (173% over control; 10 microM) in SPT activity as well as a time (265% over control)- and dose-dependent increase (215% above control; 10 microM) in ceramide synthase activity. Our results show that 4-HPR-mediated ceramide generation is derived from the de novo synthetic pathway by coordinate activation of SPT and ceramide synthase. Knowledge of these biochemical events is of utility when downstream modulators of ceramide metabolism are used to heighten the cytotoxic response to chemotherapy.

Accumulation and release of vinblastine and vincristine by HeLa cells: light microscopic, cinematographic, and biochemical study.

The effect of vinblastine (VLB) and vincristine (VCR) on the survival and proliferation of HeLa cells has been studied during continuous and after 3-hr incubations using cell counting and time lapse cinematography. VLB and VCR are accumulated in the cells during drug exposure as shown with 3H-labeled drugs. The intracellular drug concentration after a 3-hr incubation with therapeutic doses (VLB, 0.1 micrograms/ml, or VCR, 0.03 micrograms/ml) and thorough drug removal is 150 to 500 times higher than that in the incubation medium. Both drugs are released from the cells upon restoration to alkaloid-free medium reaching concentrations that are lethal to the cells during continuous incubation. There is, however, a difference in the release of the two drugs. VLB is quickly and readily released from the cells while the release of VCR occurs slowly, since VCR is tenaciously retained by the cells. Both drugs are released predominantly from living cells.