Mislocalization of pathogenic RBM20 variants in dilated cardiomyopathy is caused by loss-of-interaction with Transportin-3.

Severe forms of dilated cardiomyopathy (DCM) are associated with point mutations in the alternative splicing regulator RBM20 that are frequently located in the arginine/serine-rich domain (RS-domain). Such mutations can cause defective splicing and cytoplasmic mislocalization, which leads to the formation of detrimental cytoplasmic granules. Successful development of personalized therapies requires identifying the direct mechanisms of pathogenic RBM20 variants. Here, we decipher the molecular mechanism of RBM20 mislocalization and its specific role in DCM pathogenesis. We demonstrate that mislocalized RBM20 RS-domain variants retain their splice regulatory activity, which reveals that aberrant cellular localization is the main driver of their pathological phenotype. A genome-wide CRISPR knockout screen combined with image-enabled cell sorting identified Transportin-3 (TNPO3) as the main nuclear importer of RBM20. We show that the direct RBM20-TNPO3 interaction involves the RS-domain, and is disrupted by pathogenic variants. Relocalization of pathogenic RBM20 variants to the nucleus restores alternative splicing and dissolves cytoplasmic granules in cell culture and animal models. These findings provide proof-of-principle for developing therapeutic strategies to restore RBM20's nuclear localization in RBM20-DCM patients.

Green Labs: a guide to developing sustainable science in your organization.

Scientific research plays a vital role for society, but carries a significant environmental footprint, involving intensive use of energy and resources. Scientists are well placed to understand the unfolding climate and ecological crises, but may not appreciate how heavily their research, and other work-related activities, contribute to emissions and pollution. With the consequences of climate change and ecological breakdown playing out in real time, scientists now have an important, urgent role to play in catalyzing solutions. Here, we explore how research organizations can reduce their environmental impact, share useful resources and encourage the global community to engage in making science more sustainable.

[Differences among renin-angiotensin system inhibitor drugs in prognosis of hypertense patients with COVID-19]. / Diferencias entre fármacos inhibidores del sistema renina-angiotensina en pacientes hipertensos ingresados por COVID-19.

Introduction: Concerns have been raised about Renin-angiotensin system inhibitors (RASi) in patients with COVID-19. Although recent trials have proved its security, evidence regarding intrinsic differences between RASi is lacking, especially in patients with arterial hypertension. Our objective was to analyse the prognosis of hypertense patients who received angiotensin converting enzyme inhibitors (ACEi) or angiotensin-2 receptor blockers (ARBs) and were hospitalized due to COVID-19. Materials and methods: 392 consecutive patients with hypertension and COVID-19 were analyse. Incidence of the combined event (death or mechanical ventilation need) was the primary endpoint. Secondary, incidence of each event and time to event were analysed. Results: 155 received ACEi and 237 ARBs. During the hospitalization, the combined event was observed in the 31,6 % of patients. No differences were observed between those previously treated with ACEi and ARBs (33.5 vs. 30.9%; p = 0.51). In the survival analysis, no differences were observed regarding time to combined event (p = 0.91). In-hospital mortality was similar in both groups (32.3 vs. 29.1%; p = 0.51), as well as the need of mechanical ventilation (3.2 vs. 5.9%; p = 0.23). Conclusions: The type of RASi was not associated with in-hospital major events in patients with arterial hypertension hospitalized due to COVID-19.

Introducción: Han surgido dudas sobre la seguridad de los fármacos inhibidores del sistema renina-angiotensina (SRA) en pacientes con enfermedad por coronavirus 2019 (COVID-19). Aunque estudios recientes han demostrado la seguridad de este grupo de fármacos, la evidencia sobre la comparativa de los diferentes fármacos inhibidores del SRA es escasa, sobre todo en pacientes hipertensos. Nuestro objetivo fue analizar el pronóstico de los pacientes hipertensos tratados con inhibidores de la enzima convertidora de angiotensina (IECA) o antagonistas del receptor de angiotensina II (ARA II) que presentaron COVID-19. Materiales y métodos: Se analizaron 582 pacientes hipertensos con COVID-19. Se registró la incidencia del evento combinado de muerte o necesidad de ventilación mecánica invasiva (VMI) durante la hospitalización. De forma secundaria, se analizó la incidencia de eventos de manera independiente y se realizó un análisis de supervivencia para analizar el tiempo hasta los eventos. Resultados: 155 pacientes recibían tratamiento previo con IECA y 237 con ARA II. Durante la hospitalización por COVID-19, se observó una incidencia del evento combinado del 31.6%. No se detectaron diferencias entre los pacientes que recibían tratamiento con IECA y los tratados con ARA II (33.5 vs. 30.9%; p = 0.51). En el análisis de supervivencia, no se hallaron diferencias en el tiempo hasta el evento combinado (p = 0.91). La mortalidad intrahospitalaria fue similar en ambos grupos (32.3 vs. 29.1%; p = 0.51), así como la necesidad de VMI (3.2 vs. 5.9%; p = 0.23). Conclusiones: El tipo de inhibidor del SRA no se asoció a diferencias pronósticas significativas entre los pacientes hipertensos ingresados con COVID-19.

Molecular biology for green recovery-A call for action.

Molecular biology holds a vast potential for tackling climate change and biodiversity loss. Yet, it is largely absent from the current strategies. We call for a community-wide action to bring molecular biology to the forefront of climate change solutions.

Aprotinin treatment against SARS-CoV-2: A randomized phase III study to evaluate the safety and efficacy of a pan-protease inhibitor for moderate COVID-19.

BACKGROUND: SARS-CoV-2 virus requires host proteases to cleave its spike protein to bind to its ACE2 target through a two-step furin-mediated entry mechanism. Aprotinin is a broad-spectrum protease inhibitor that has been employed as antiviral drug for other human respiratory viruses. Also, it has important anti-inflammatory properties for inhibiting the innate immunity contact system. METHODS: This was a multicentre, double-blind, randomized trial performed in four Spanish hospitals comparing standard treatment versus standard treatment + aprotinin for patients with COVID-19 between 20 May 2020 and 20 October 2021. The primary efficacy outcomes were length of hospital stay and ICU admission. The secondary endpoints were each of the primary efficacy outcomes and a composite of oxygen therapy, analytical parameters and death. Safety outcomes included adverse reactions to treatment during a 30-day follow-up period. Treatment was given for 11 days or till discharge. RESULTS: With almost identical analytical profiles, significant differences were observed in treatment time, which was 2 days lower in the aprotinin group (p = .002), and length of hospital admission, which was 5 days shorter in the aprotinin group (p = .003). The incidence of discharge was 2.19 times higher (HR: 2.188 [1.182-4.047]) in the aprotinin group than in the placebo group (p = .013). In addition, the aprotinin-treated group required less oxygen therapy and had no adverse reactions or side effects. CONCLUSION: Inhaled aprotinin may improve standard treatment and clinical outcomes in hospitalized patients with COVID-19, resulting in a shorter treatment time and hospitalization compared with the placebo group. The administration of aprotinin was safe.

High-speed fluorescence image-enabled cell sorting.

Fast and selective isolation of single cells with unique spatial and morphological traits remains a technical challenge. Here, we address this by establishing high-speed image-enabled cell sorting (ICS), which records multicolor fluorescence images and sorts cells based on measurements from image data at speeds up to 15,000 events per second. We show that ICS quantifies cell morphology and localization of labeled proteins and increases the resolution of cell cycle analyses by separating mitotic stages. We combine ICS with CRISPR-pooled screens to identify regulators of the nuclear factor κB (NF-κB) pathway, enabling the completion of genome-wide image-based screens in about 9 hours of run time. By assessing complex cellular phenotypes, ICS substantially expands the phenotypic space accessible to cell-sorting applications and pooled genetic screening.

Análisis de la relación entre los inhibidores del sistema renina-angiotensina y la evolución de pacientes hospitalizados por infección respiratoria COVID-19 / Comparative analysis between the use of renin-angiotensin system antagonists and clinical outcomes of hospitalized patients with COVID-19 respiratory infection

INTRODUCCIÓN: La presencia de hipertensión arterial se asocia con peor pronóstico en pacientes con COVID-19, y se ha sugerido que el uso de inhibidores del eje renina-angiotensina puede influir en el pronóstico de los pacientes. MÉTODOS: Registro observacional de 921 pacientes consecutivos ingresados por infección respiratoria COVID-19 entre el 1 de marzo y el 30 abril de 2020 en el Hospital General Universitario de Ciudad Real. Se registraron datos clínicos y analíticos, intervenciones terapéuticas y desarrollo de eventos durante el ingreso hospitalario. RESULTADOS: La mediana de edad fue de 78 años y el 59,2% tenían hipertensión arterial. Aunque el perfil clínico fue más desfavorable en el grupo de pacientes con prescripción previa de IECA o ARA2 respecto al resto, los primeros presentaron menor riesgo de desarrollo del evento primario combinado (mortalidad total o necesidad de soporte ventilatorio invasivo). Asimismo, el empleo previo al ingreso o durante el mismo de estos fármacos mostró un efecto neutro sobre la mortalidad total y sobre la necesidad de ventilación mecánica invasiva. En el análisis de supervivencia no se observó mayor riesgo de presentar más precozmente ninguno de los eventos registrados. CONCLUSIONES: La prescripción previa al ingreso por infección respiratoria COVID-19 de inhibidores del eje renina-angiotensina se asoció a un menor riesgo de desarrollo del evento primario combinado y a un efecto neutro sobre la mortalidad total y sobre la necesidad de ventilación mecánica invasiva

INTRODUCTION: Hypertension has been associated with worse outcomes in patients with COVID-19 infection, so concerns have been raised about the possibility that inhibitors of the renin-angiotensin system (RAS) could influence the prognosis of these patients. METHODS: This is an observational study of 921 consecutive patients admitted with COVID-19 respiratory infection to Hospital General Universitario Ciudad Real from March 1 to April 30, 2020. Following data were collected including patient demographic information, medical history, clinical characteristics, laboratory data, therapeutic interventions during the hospitalization and clinical outcomes. RESULTS: The mean age was 78 years, and 59.2% of patients had a history of hypertension. Patients with previous treatment with RAS inhibitor (42.4%) showed lower risk of the primary composite endpoint (mortality or need for invasive mechanical ventilation). Treatment with RAS inhibitor (both outpatient treatment and during hospitalization) had neither effect on mortality nor need for invasive ventilation. There were no differences in time-to-event analysis between groups. CONCLUSIONS: RAS inhibitor treatment prior to admission in patients with COVID-19 respiratory infection was associated with lower risk of the primary composite endpoint and did not show neither impact on mortality nor need for invasive mechanical ventilation, even if these drugs were prescribed during hospitalization

Comparative analysis between the use of renin-angiotensin system antagonists and clinical outcomes of hospitalized patients with COVID-19 respiratory infection.

INTRODUCTION: Hypertension has been associated with worse outcomes in patients with COVID-19 infection, so concerns have been raised about the possibility that inhibitors of the renin-angiotensin system (RAS) could influence the prognosis of these patients. METHODS: This is an observational study of 921 consecutive patients admitted with COVID-19 respiratory infection to Hospital General Universitario Ciudad Real from March 1 to April 30, 2020. Following data were collected including patient demographic information, medical history, clinical characteristics, laboratory data, therapeutic interventions during the hospitalization and clinical outcomes. RESULTS: The mean age was 78 years, and 59.2% of patients had a history of hypertension. Patients with previous treatment with RAS inhibitor (42.4%) showed lower risk of the primary composite endpoint (mortality or need for invasive mechanical ventilation). Treatment with RAS inhibitor (both outpatient treatment and during hospitalization) had neither effect on mortality nor need for invasive ventilation. There were no differences in time-to-event analysis between groups. CONCLUSIONS: RAS inhibitor treatment prior to admission in patients with COVID-19 respiratory infection was associated with lower risk of the primary composite endpoint and did not show neither impact on mortality nor need for invasive mechanical ventilation, even if these drugs were prescribed during hospitalization.

INTRODUCCIÓN: La presencia de hipertensión arterial se asocia con peor pronóstico en pacientes con COVID-19, y se ha sugerido que el uso de inhibidores del eje renina-angiotensina puede influir en el pronóstico de los pacientes. MÉTODOS: Registro observacional de 921 pacientes consecutivos ingresados por infección respiratoria COVID-19 entre el 1 de marzo y el 30 abril de 2020 en el Hospital General Universitario de Ciudad Real. Se registraron datos clínicos y analíticos, intervenciones terapéuticas y desarrollo de eventos durante el ingreso hospitalario. RESULTADOS: La mediana de edad fue de 78 años y el 59,2% tenían hipertensión arterial. Aunque el perfil clínico fue más desfavorable en el grupo de pacientes con prescripción previa de IECA o ARA2 respecto al resto, los primeros presentaron menor riesgo de desarrollo del evento primario combinado (mortalidad total o necesidad de soporte ventilatorio invasivo). Asimismo, el empleo previo al ingreso o durante el mismo de estos fármacos mostró un efecto neutro sobre la mortalidad total y sobre la necesidad de ventilación mecánica invasiva. En el análisis de supervivencia no se observó mayor riesgo de presentar más precozmente ninguno de los eventos registrados. CONCLUSIONES: La prescripción previa al ingreso por infección respiratoria COVID-19 de inhibidores del eje renina-angiotensina se asoció a un menor riesgo de desarrollo del evento primario combinado y a un efecto neutro sobre la mortalidad total y sobre la necesidad de ventilación mecánica invasiva.

Annotation matters: validating the discovery of cancer drivers.

Advanced sequencing techniques have helped unveil numerous new, potential cancer driver mutations. However, manual curation and analysis of gene and protein annotation are essential to verify such discoveries. Our recent study of STK19 (Serine Threonine Kinase 19), a previously identified melanoma driver, is a clear example of the importance of such detailed analysis, with both STK19 gene and protein annotations in frequently used databases having been proven incorrect.

A predictable conserved DNA base composition signature defines human core DNA replication origins.

DNA replication initiates from multiple genomic locations called replication origins. In metazoa, DNA sequence elements involved in origin specification remain elusive. Here, we examine pluripotent, primary, differentiating, and immortalized human cells, and demonstrate that a class of origins, termed core origins, is shared by different cell types and host ~80% of all DNA replication initiation events in any cell population. We detect a shared G-rich DNA sequence signature that coincides with most core origins in both human and mouse genomes. Transcription and G-rich elements can independently associate with replication origin activity. Computational algorithms show that core origins can be predicted, based solely on DNA sequence patterns but not on consensus motifs. Our results demonstrate that, despite an attributed stochasticity, core origins are chosen from a limited pool of genomic regions. Immortalization through oncogenic gene expression, but not normal cellular differentiation, results in increased stochastic firing from heterochromatin and decreased origin density at TAD borders.

Impact of Treatment with Renin-Angiotensin System Inhibitors on Clinical Outcomes in Hypertensive Patients Hospitalized with COVID-19.

INTRODUCTION: Concerns have been raised about the possible harmfulness of angiotensin-converter enzyme inhibitors (ACEi) and aldosterone receptor blockers (ARB) in patients with COVID-19. However, few data from a European population have been published, especially from hypertensive patients. AIM: To study the association between ACEi or ARB treatments and major adverse outcomes during hospitalisation in COVID-19 patients. METHODS: We studied 545 consecutive hypertensive patients admitted to our institution due to COVID-19 with respiratory involvement. We analysed the incidence of combined event (death or mechanical ventilatory support) during hospitalisation, as well as the time to independent events. RESULTS: 188 (34.5%) patients presented the combined endpoint. 182 (33.4%) patients died, and 21 (3.9%) needed mechanical ventilatory support. Patients with previous treatment with ACEi or ARB presented similar incidence of the combined endpoint during hospitalisation (31.6% vs. 41.8%; p = 0.08), with a lower all-cause mortality rate (30.4% vs. 41.2%; p = 0.03) compared with those without prior treatment. Use of ACEi or ARB was not independently associated with lower incidence of the combined endpoint [Adjusted OR 0.675 (95% CI 0.298-1.528; p = 0.146)], but it was associated with lower mortality [Adjusted OR 0.550 (95% CI 0.304-0.930; p = 0.047)]. CONCLUSIONS: The use of ACEi or ARB was associated with less incidence of all-cause death during hospitalisation among hypertensive patients admitted with COVID-19 respiratory infection.

[Comparative analysis between the use of renin-angiotensin system antagonists and clinical outcomes of hospitalized patients with COVID-19 respiratory infection]. / Análisis de la relación entre los inhibidores del sistema renina-angiotensina y la evolución de pacientes hospitalizados por infección respiratoria COVID-19.

INTRODUCTION: Hypertension has been associated with worse outcomes in patients with COVID-19 infection, so concerns have been raised about the possibility that inhibitors of the renin-angiotensin system (RAS) could influence the prognosis of these patients. METHODS: This is an observational study of 921 consecutive patients admitted with COVID-19 respiratory infection to Hospital General Universitario Ciudad Real from March 1 to April 30, 2020. Following data were collected including patient demographic information, medical history, clinical characteristics, laboratory data, therapeutic interventions during the hospitalization and clinical outcomes. RESULTS: The mean age was 78years, and 59.2% of patients had a history of hypertension. Patients with previous treatment with RAS inhibitor (42.4%) showed lower risk of the primary composite endpoint (mortality or need for invasive mechanical ventilation). Treatment with RAS inhibitor (both outpatient treatment and during hospitalization) had neither effect on mortality nor need for invasive ventilation. There were no differences in time-to-event analysis between groups. CONCLUSIONS: RAS inhibitor treatment prior to admission in patients with COVID-19 respiratory infection was associated with lower risk of the primary composite endpoint and did not show neither impact on mortality nor need for invasive mechanical ventilation, even if these drugs were prescribed during hospitalization.

Multiplex Cell Fate Tracking by Flow Cytometry.

Measuring differences in cell cycle progression is often essential to understand cell behavior under different conditions, treatments and environmental changes. Cell synchronization is widely used for this purpose, but unfortunately, there are many cases where synchronization is not an option. Many cell lines, patient samples or primary cells cannot be synchronized, and most synchronization methods involve exposing the cells to stress, which makes the method incompatible with the study of stress responses such as DNA damage. The use of dual-pulse labelling using EdU and BrdU can potentially overcome these problems, but the need for individual sample processing may introduce a great variability in the results and their interpretation. Here, we describe a method to analyze cell proliferation and cell cycle progression by double staining with thymidine analogues in combination with fluorescent cell barcoding, which allows one to multiplex the study and reduces the variability due to individual sample staining, reducing also the cost of the experiment.

Evidence That STK19 Is Not an NRAS-dependent Melanoma Driver.

STK19 was proposed to be a cancer driver, and recent work by Yin et al. (2019) in Cell suggested that the frequently recurring STK19 D89N substitution represents a gain-of-function change, allowing increased phosphorylation of NRAS to enhance melanocyte transformation. Here we show that the STK19 gene has been incorrectly annotated, and that the expressed protein is 110 amino acids shorter than indicated by current databases. The "cancer driving" STK19 D89N substitution is thus outside the coding region. We also fail to detect evidence of the mutation affecting STK19 expression; instead, it is a UV signature mutation, found in the promoter of other genes as well. Furthermore, STK19 is exclusively nuclear and chromatin-associated, while no evidence for it being a kinase was found. The data in this Matters Arising article raise fundamental questions about the recently proposed role for STK19 in melanoma progression via a function as an NRAS kinase, suggested by Yin et al. (2019) in Cell. See also the response by Yin et al. (2020), published in this issue.

Regulation of the RNAPII Pool Is Integral to the DNA Damage Response.

In response to transcription-blocking DNA damage, cells orchestrate a multi-pronged reaction, involving transcription-coupled DNA repair, degradation of RNA polymerase II (RNAPII), and genome-wide transcription shutdown. Here, we provide insight into how these responses are connected by the finding that ubiquitylation of RNAPII itself, at a single lysine (RPB1 K1268), is the focal point for DNA-damage-response coordination. K1268 ubiquitylation affects DNA repair and signals RNAPII degradation, essential for surviving genotoxic insult. RNAPII degradation results in a shutdown of transcriptional initiation, in the absence of which cells display dramatic transcriptome alterations. Additionally, regulation of RNAPII stability is central to transcription recovery-persistent RNAPII depletion underlies the failure of this process in Cockayne syndrome B cells. These data expose regulation of global RNAPII levels as integral to the cellular DNA-damage response and open the intriguing possibility that RNAPII pool size generally affects cell-specific transcription programs in genome instability disorders and even normal cells.

The gastrula transition reorganizes replication-origin selection in Caenorhabditis elegans.

Although some features underlying replication-origin activation in metazoan cells have been determined, little is known about their regulation during metazoan development. Using the nascent-strand purification method, here we identified replication origins throughout Caenorhabditis elegans embryonic development and found that the origin repertoire is thoroughly reorganized after gastrulation onset. During the pluripotent embryonic stages (pregastrula), potential cruciform structures and open chromatin are determining factors that establish replication origins. The observed enrichment of replication origins in transcription factor-binding sites and their presence in promoters of highly transcribed genes, particularly operons, suggest that transcriptional activity contributes to replication initiation before gastrulation. After the gastrula transition, when embryonic differentiation programs are set, new origins are selected at enhancers, close to CpG-island-like sequences, and at noncoding genes. Our findings suggest that origin selection coordinates replication initiation with transcriptional programs during metazoan development.

The utility of hyperthermic intra-abdominal chemotherapy with gemcitabine for the inhibition of tumor progression in an experimental model of pancreatic peritoneal carcinomatosis, in relation to their behavior with pancreatic cancer stem cells CD133+ CXCR4.

OBJECTIVE: The origin of pancreatic cancer has been identified as a population of malignant pancreatic stem cells CD133+ CXCR4+ immunophenotype. These cells have high capacity for early locoregional invasion, being responsible for early recurrence and high mortality rates of pancreatic cancer. We propose a study for decreasing tumor progression of pancreatic cancer by reducing the volume and neoplastic subpopulation of pancreatic cancer stem cells CD133+ CXCR4+. Therefore, we develop a new therapeutic model, characterized by the application of HIPEC (Hyperthermic Intraperitoneal Chemotherapy) with gemcitabine. DESIGN: Pancreatic tumor cell line: human cell line BxPC-3. The animal model involved 18 immunosuppressed rats 5 weeks weighing 150-200 gr. The implantation of 13 × 10(6) cells/mL was performed with homogeneous distribution in the 13 abdominopelvic quadrants according to the peritoneal carcinomatosis index (PCI) and were randomized into three treatment groups. Group I (4 rats) received intravenous saline. Group II (6 rats) received intravenous gemcitabine. Group III (8 rats) received HIPEC at 41 °C for 30 min with gemcitabine + gemcitabine IV. A histological study confirmed pancreatic cancer and immunohistochemical quantification of pancreatic cancer stem cells CD133+ CXCR4+ tumor cells. RESULTS: There was a population decline of pancreatic cancer stem cells CD133+ CXCR4+ in the HIPEC group with respect to the other two groups (p < 0.001). There was a decrease in PCI between treatment groups (p < 0.05). CONCLUSION: The initial results are encouraging since there is a declining population of cancer stem cells CD133+ CXCR4+ in the HIPEC group and decreased tumor volume compared to the other two treatment groups. All the conclusions are only valid for BxPC3 cell line, and the effects HIPEC on Kras-driven pancreatic tumors remain to be determined.

Multiomic Analysis of the UV-Induced DNA Damage Response.

In order to facilitate the identification of factors and pathways in the cellular response to UV-induced DNA damage, several descriptive proteomic screens and a functional genomics screen were performed in parallel. Numerous factors could be identified with high confidence when the screen results were superimposed and interpreted together, incorporating biological knowledge. A searchable database, bioLOGIC, which provides access to relevant information about a protein or process of interest, was established to host the results and facilitate data mining. Besides uncovering roles in the DNA damage response for numerous proteins and complexes, including Integrator, Cohesin, PHF3, ASC-1, SCAF4, SCAF8, and SCAF11, we uncovered a role for the poorly studied, melanoma-associated serine/threonine kinase 19 (STK19). Besides effectively uncovering relevant factors, the multiomic approach also provides a systems-wide overview of the diverse cellular processes connected to the transcription-related DNA damage response.

Experimental development of an intra-abdominal chemohyperthermia model using a closed abdomen technique and a PRS-1.0 Combat CO2 recirculation system.

BACKGROUND: Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy is the best operative treatment currently available for patients with peritoneal carcinomatosis of ovarian origin. The open abdomen technique is the classic technique for hyperthermic intraperitoneal chemotherapy. We developed a closed abdomen model that improves temperature control and increases exposure of peritoneal surfaces to the drug by recirculating the perfusate. METHODS: We used a porcine model with 12 female, Large White pigs-4 in the open technique group and 8 in the closed technique CO2 group. We performed cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for 60 minutes using paclitaxel (175 mg/m(2)) at an input temperature of 42°C. Perfusate recirculation was performed under controlled pressure (range, 12-15 mmHg). The infusion of 0.7 L of CO2 via a separate intraperitoneal infusion catheter mixed the perfusate within the peritoneal cavity. Intra-abdominal temperature was assessed using 6 intra-abdominal temperature probes and 2 temperature probes in the inflow and outflow circuits. Drug distribution was assessed using methylene blue staining. RESULTS: Intra-abdominal temperatures remained constant and homogeneous in all intra-abdominal quadrants with a constant input temperature of 42°C and a minimum output temperature of 41.4°C. The infused CO2 caused the fluid to bubble and created agitation inside the abdominal cavity to facilitate a homogeneous distribution of the drug-containing perfusate. CONCLUSION: The closed recirculation hyperthermia with intraperitoneal chemotherapy technique developed in this study is safe and feasible, and may provide a more homogeneous delivery of heated chemotherapy to the peritoneal cavity in patients with peritoneal malignancies.