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Background: Violation of the integrity of the airway (pulmonary parenchymal air leak or tracheobronchial injury) remains a challenging problem in chest medicine and thoracic surgery. Tissue sealants such as fibrin glue have been suggested to improve outcomes but they are still associated with significant failure rates. Laser tissue welding (LTW) is an alternative method that produces wound repairs that are significantly stronger than those of fibrin glue and may be used to repair air leaks.Methods: We used an Institutional Animal Care and Use Committees-approved New Zealand white rabbit model of lung parenchymal and tracheal injury. Lung wounds (n = 8 per condition) were created and either left open or repaired using fibrin glue or LTW. Tracheal wounds (n = 5 per condition) were created using incisions in the membranous and cartilaginous portions or by removing a tracheal ring, and were repaired using LTW. Within each tissue type, the burst strength of the wounds was measured using a digital manometer and were compared with one another using a two-tailed, paired Student t test.Results: Among the lung injuries, the burst strength of the LTW repair (19.95 +/- 4.98 mm Hg) was significantly stronger than that of the fibrin glue repair or open wound (10.53 +/- 5.01 mm Hg, P = .001, and 7.61 +/- 2.64 mm Hg, P < .001, respectively). Among the tracheal injuries, the burst strength of the membranous incision (101.00 +/- 20.25 mm Hg) was significantly higher than that of the cartilaginous incision (75.08 +/- 10.50 mm Hg, P = .03) but not that of the cartilaginous defect (77.34 +/- 12.35 mm Hg).Conclusions: LTW is capable of sealing wounds in the tracheobronchial tree and can produce bonds that are twice as strong as fibrin glue in lung parenchyma. LTW may be a better alternative than fibrin glue in the repair of injuries to the airway. [ABSTRACT FROM AUTHOR]

Background: The increasing aging population presents a significant challenge, accompanied by a shortage of professional caregivers, adding to the therapeutic burden. Clinical decision support systems, utilizing computerized clinical guidelines, can improve healthcare quality, reduce expenses, save time, and boost caregiver efficiency., Objectives: 1) Develop and evaluate an automated quality assessment (QA) system for retrospective longitudinal care quality analysis, focusing on clinical staff adherence to evidence-based guidelines (GLs). 2) Assess the system's technical feasibility and functional capability for senior nurse use in geriatric pressure-ulcer management., Methods: A computational QA system using our Quality Assessment Temporal Patterns (QATP) methodology was designed and implemented. Our methodology transforms the GL's procedural-knowledge into declarative-knowledge temporal-abstraction patterns representing the expected execution trace in the patient's data for correct therapy application. Fuzzy temporal logic allows for partial compliance, reflecting individual and grouped action performance considering their values and temporal aspects. The system was tested using a pressure ulcer treatment GL and data from 100 geriatric patients' Electronic Medical Records (EMR). After technical evaluation for accuracy and feasibility, an extensive functional evaluation was conducted by an experienced nurse, comparing QA scores with and without system support, and versus automated system scores. Time efficiency was also measured., Results: QA scores from the geriatric nurse, with and without system's support, did not significantly differ from those provided by the automated system (p < 0.05), demonstrating the effectiveness and reliability of both manual and automated methods. The system-supported manual QA process reduced scoring time by approximately two-thirds, from an average of 17.3 min per patient manually to about 5.9 min with the system's assistance, highlighting the system's efficiency potential in clinical practice., Conclusion: The QA system based on QATP, produces scores consistent with an experienced nurse's assessment for complex care over extended periods. It enables quick and accurate quality care evaluation for multiple patients after brief training. Such automated QA systems may empower nursing staff, enabling them to manage more patients, accurately and consistently, while reducing costs due to saved time and effort, and enhanced compliance with evidence-based guidelines., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

To understand human longevity, inherent aging processes must be distinguished from known etiologies leading to age-related chronic diseases. Such deconvolution is difficult to achieve because it requires tracking patients throughout their entire lives. Here, we used machine learning to infer health trajectories over the entire adulthood age range using extrapolation from electronic medical records with partial longitudinal coverage. Using this approach, our model tracked the state of patients who were healthy and free from known chronic disease risk and distinguished individuals with higher or lower longevity potential using a multivariate score. We showed that the model and the markers it uses performed consistently on data from Israeli, British and US populations. For example, mildly low neutrophil counts and alkaline phosphatase levels serve as early indicators of healthy aging that are independent of risk for major chronic diseases. We characterize the heritability and genetic associations of our longevity score and demonstrate at least 1 year of extended lifespan for parents of high-scoring patients compared to matched controls. Longitudinal modeling of healthy individuals is thereby established as a tool for understanding healthy aging and longevity., (© 2023. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Background: Several genetic variants are associated with chronic liver disease. The role of these variants in outcomes after liver transplantation (LT) is uncertain. The aim of this study was to determine if donor genotype at risk-associated variants in PNPLA3 (rs738409 C>G, p.I148M) and HSD17B13 (rs72613567 T>TA; rs80182459, p.A192Lfs∗8) influences post-LT survival., Methods: In this retrospective cohort study, data on 2346 adults who underwent first-time LT between January 1, 1999 and June 30, 2020 and who had donor DNA samples available at five large Transplant Immunology Laboratories in Texas, USA, were obtained from the United Network for Organ Sharing (UNOS). Duplicates, patients with insufficient donor DNA for genotyping, those who were <18 years of age at the time of transplant, had had a previous transplant or had missing genotype data were excluded. The primary outcomes were patient and graft survival after LT. The association between donor genotype and post-LT survival was examined using Kaplan-Meier method and multivariable-adjusted Cox proportional hazards models., Findings: Median age of LT recipients was 57 [interquartile range (IQR), 50-62] years; 837 (35.7%) were women; 1362 (58.1%) White, 713 (30.4%) Hispanic, 182 (7.8%) Black/African-American. Median follow-up time was 3.95 years. Post-LT survival was not affected by donor PNPLA3 genotype but was significantly reduced among recipients of livers with two HSD17B13 loss-of-function (LoF) variants compared to those receiving livers with no HSD17B13 LoF alleles (unadjusted one-year survival: 82.6% vs 93.9%, P  < 0.0001; five-year survival: 73.1% vs 82.9%, P  = 0.0017; adjusted hazard ratio [HR], 2.25; 95% CI, 1.61-3.15 after adjustment for recipient age, sex, and self-reported ethnicity). Excess mortality was restricted to those receiving steroid induction immunosuppression (crude 90-day post-LT mortality, 9.3% [95% CI, 1.9%-16.1%] vs 1.9% [95% CI, 0.9%-2.9%] in recipients of livers with two vs no HSD17B13 LoF alleles, P  = 0.0012; age, sex, and ethnicity-adjusted HR, 2.85; 95% CI, 1.72-4.71, P  < 0.0001). No reduction was seen among patients who did not receive steroid induction (90-day mortality 3.1% [95% CI, 0%-7.3%] vs 2% [95% CI, 0.9%-3.1%], P  = 0.65; adjusted HR, 1.17; 95% CI, 0.66-2.08, P  = 0.60)., Interpretation: Donor HSD17B13 genotype adversely affects post-LT survival in patients receiving steroid induction. Additional studies are required to confirm this association., Funding: The National Institutes of Health and American Society of Transplant Surgeons Collaborative Scientist Grant., Competing Interests: All authors declare no competing interests., (© 2023 The Authors.)

The tumor microenvironment hosts antibody-secreting cells (ASCs) associated with a favorable prognosis in several types of cancer. Patient-derived antibodies have diagnostic and therapeutic potential; yet, it remains unclear how antibodies gain autoreactivity and target tumors. Here, we found that somatic hypermutations (SHMs) promote antibody antitumor reactivity against surface autoantigens in high-grade serous ovarian carcinoma (HGSOC). Patient-derived tumor cells were frequently coated with IgGs. Intratumoral ASCs in HGSOC were both mutated and clonally expanded and produced tumor-reactive antibodies that targeted MMP14, which is abundantly expressed on the tumor cell surface. The reversion of monoclonal antibodies to their germline configuration revealed two types of classes: one dependent on SHMs for tumor binding and a second with germline-encoded autoreactivity. Thus, tumor-reactive autoantibodies are either naturally occurring or evolve through an antigen-driven selection process. These findings highlight the origin and potential applicability of autoantibodies directed at surface antigens for tumor targeting in cancer patients., Competing Interests: Declaration of interests The antibodies reported in the article are in the process of being patented., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: To describe laryngeal findings and voice quality in patients with suspected lung cancer, relative to voice quality and possible laryngeal pathology., Study Design: Prospective cohort study., Setting: Tertiary care center., Methods: Patients with known or suspected lung cancer were approached before planned thoracic surgery, and they completed acoustic analysis, the Voice-Related Quality of Life (V-RQOL) questionnaire, and stroboscopy. The prevalence of dysphonia, V-RQOL and Cepstral Spectral Index of Dysphonia (CSID) scores, and laryngeal findings were examined and compared between patients ultimately found to have lung cancer and those without cancer., Results: Sixty-one patients (45 cancer, 16 noncancer) were analyzed. Patients with cancer were older than those without (mean ± SD, 72.3 ± 9.94 vs 62.6 ± 9.30 years; P = .001). Otherwise, the distribution of stroboscopy findings, acoustic measures, and self-reported voice handicap were similar between the cancer and noncancer cohorts. Prior to surgery, no patients had vocal cord paralysis or obvious neoplasm, though 4 (6.56%) had leukoplakia and 28 (45.9%) had vocal fold movement asymmetry on stroboscopy. Overall, 21 patients (35.0%) had average CSID scores >19, and 13 (21.7%) had CSID scores >24; however, only 4 self-described their voice as not working as it should, and only 2 had a V-RQOL score <85., Conclusion: Patients with suspected lung cancer have moderate dysphonia on acoustic measures, though self-reported impact on quality of life is low. While leukoplakia was seen in 4 patients, obvious neoplasm and occult paralysis were not seen in this cohort. Together, these findings suggest that patients with suspected lung cancer should be assessed for subjective voice dysfunction, but routine laryngeal screening may otherwise be unnecessary.

Standardized lab tests are central for patient evaluation, differential diagnosis and treatment. Interpretation of these data is nevertheless lacking quantitative and personalized metrics. Here we report on the modeling of 2.1 billion lab measurements of 92 different lab tests from 2.8 million adults over a span of 18 years. Following unsupervised filtering of 131 chronic conditions and 5,223 drug-test pairs we performed a virtual survey of lab tests distributions in healthy individuals. Age and sex alone explain less than 10% of the within-normal test variance in 89 out of 92 tests. Personalized models based on patients' history explain 60% of the variance for 17 tests and over 36% for half of the tests. This allows for systematic stratification of the risk for future abnormal test levels and subsequent emerging disease. Multivariate modeling of within-normal lab tests can be readily implemented as a basis for quantitative patient evaluation., (© 2021. The Author(s), under exclusive licence to Springer Nature America, Inc.)

The lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2',5-dichloro-4'-nitrosalicylanilide (niclosamide) are added to Great Lakes tributaries to target the sea lamprey, an invasive parasitic fish. This study examines the photochemical behavior of the lampricides in Carpenter Creek, Sullivan Creek, and the Manistique River. The observed loss of TFM in Carpenter and Sullivan Creeks (i.e., 34 and 19%) was similar to the loss of bromide in parallel time of passage studies (i.e., 30 and 29%), demonstrating that TFM photodegradation was minimal in both tributaries during the lampricide application. Furthermore, the absence of inorganic and organic photoproducts in the Manistique River demonstrates that TFM and niclosamide photodegradation was minimal in this large tributary, despite its long residence time (i.e., 3.3 days). Kinetic modeling was used to identify environmental variables primarily responsible for the limited photodegradation of TFM in the field compared to estimates from laboratory data. This analysis demonstrates that the lack of TFM photodegradation was attributable to the short residence times in Carpenter and Sullivan Creeks, while depth, time of year, time of day, and cloud cover influenced photochemical fate in the Manistique River. The modeling approach was extended to assess how many of the 140 United States tributaries treated with lampricides in 2015 and 2016 were amenable to TFM photolysis. While >50% removal of TFM due to photolysis could occur in 13 long and shallow tributaries, in most systems lampricides will reach the Great Lakes untransformed.

Stable maintenance of gene regulatory programs is essential for normal function in multicellular organisms. Epigenetic mechanisms, and DNA methylation in particular, are hypothesized to facilitate such maintenance by creating cellular memory that can be written during embryonic development and then guide cell-type-specific gene expression. Here we develop new methods for quantitative inference of DNA methylation turnover rates, and show that human embryonic stem cells preserve their epigenetic state by balancing antagonistic processes that add and remove methylation marks rather than by copying epigenetic information from mother to daughter cells. In contrast, somatic cells transmit considerable epigenetic information to progenies. Paradoxically, the persistence of the somatic epigenome makes it more vulnerable to noise, since random epimutations can accumulate to massively perturb the epigenomic ground state. The rate of epigenetic perturbation depends on the genomic context, and, in particular, DNA methylation loss is coupled to late DNA replication dynamics. Epigenetic perturbation is not observed in the pluripotent state, because the rapid turnover-based equilibrium continuously reinforces the canonical state. This dynamic epigenetic equilibrium also explains how the epigenome can be reprogrammed quickly and to near perfection after induced pluripotency.

DNA methylation has been comprehensively profiled in normal and cancer cells, but the dynamics that form, maintain and reprogram differentially methylated regions remain enigmatic. Here, we show that methylation patterns within populations of cells from individual somatic tissues are heterogeneous and polymorphic. Using in vitro evolution of immortalized fibroblasts for over 300 generations, we track the dynamics of polymorphic methylation at regions developing significant differential methylation on average. The data indicate that changes in population-averaged methylation occur through a stochastic process that generates a stream of local and uncorrelated methylation aberrations. Despite the stochastic nature of the process, nearly deterministic epigenetic remodeling emerges on average at loci that lose or gain resistance to methylation accumulation. Changes in the susceptibility to methylation accumulation are correlated with changes in histone modification and CTCF occupancy. Characterizing epigenomic polymorphism within cell populations is therefore critical to understanding methylation dynamics in normal and cancer cells.

Mammalian CpG islands are key epigenomic elements that were first characterized experimentally as genomic fractions with low levels of DNA methylation. Currently, CpG islands are defined based on their genomic sequences alone. Here, we develop evolutionary models to show that several distinct evolutionary processes generate and maintain CpG islands. One central evolutionary regime resulting in enriched CpG content is driven by low levels of DNA methylation and consequentially low rates of CpG deamination. Another major force forming CpG islands is biased gene conversion that stabilizes constitutively methylated CpG islands by balancing rapid deamination with CpG fixation. Importantly, evolutionary analysis and population genetics data suggest that selection for high CpG content is not a significant factor contributing to conservation of CpGs in differentially methylated regions. The heterogeneous, but not selective, origins of CpG islands have direct implications for the understanding of DNA methylation patterns in healthy and diseased cells., (Copyright © 2011 Elsevier Inc. All rights reserved.)

DNA methylation is an important epigenetic mechanism, affecting normal development and playing a key role in reprogramming epigenomes during stem cell derivation. Here we report on DNA methylation patterns in native monkey embryonic stem cells (ESCs), fibroblasts, and ESCs generated through somatic cell nuclear transfer (SCNT), identifying and comparing epigenome programming and reprogramming. We characterize hundreds of regions that are hyper- or hypomethylated in fibroblasts compared to native ESCs and show that these are conserved in human cells and tissues. Remarkably, the vast majority of these regions are reprogrammed in SCNT ESCs, leading to almost perfect correlation between the epigenomic profiles of the native and reprogrammed lines. At least 58% of these changes are correlated in cis to transcription changes, Polycomb Repressive Complex-2 occupancy, or binding by the CTCF insulator. We also show that while epigenomic reprogramming is extensive and globally accurate, the efficiency of adding and stripping DNA methylation during reprogramming is regionally variable. In several cases, this variability results in regions that remain methylated in a fibroblast-like pattern even after reprogramming.

Background: We have previously shown that metabolic arrest induced with ATP-regulated potassium channel openers (PCOs) can improve lung preservation by adding Aprikalim (a PCO, Rhone-Poulene Roher) to modified Euro-Collins solution for pulmonary artery flush. Because the membrane hyperpolarizing effects of a PCO potentially competes with the depolarizing effects of a hyperkalemic solution, this study evaluated the effects of the potassium gradient on PCO-mediated lung protection., Study Design: Twenty rabbits underwent lung protection in four groups. Group 1 underwent harvest and reperfusion as a "no ischemia" control. Groups 2, 3, and 4 underwent harvest followed by 18 hours of cold ischemic storage before reperfusion. Groups 1 and 4 received Euro Collins as the pulmonary flush at induction of ischemia. Group 2 received Euro Collins plus Aprikalim (100 microM); and group 3 received lactated Ringer's plus Aprikalim. After ischemic storage, the lungs were reperfused with autologous blood for 2 hours. Every 30 minutes, the lungs were given a 10-minute 100% fractional inspired oxygen (F(i)O(2)) challenge to measure maximal gas exchange as an indication of graft function., Results: Repeated measures ANOVA showed Aprikalim improved graft function after 18 hours of cold ischemia (p < 0.0001). No significant differences were found when Aprikalim was used in either Euro-Collins (group 2) or lactated Ringer's (group 3) solution., Conclusions: The ability of the PCO Aprikalim to preserve gas exchange in a model of hypothermic pulmonary ischemia-reperfusion injury was not affected by the plasmolemmal potassium gradient. This is consistent with recent findings in myocardial protection studies that the protective effects of PCOs may be intracellular.

Background: A horizontally integrated multidisciplinary clinical guideline was created and implemented in 1999-2000 for minimally invasive thoracic surgery (MIS). Guideline elements included complete appropriate preoperative evaluation, minimally invasive surgery techniques, aggressive anesthetic management and absolute pain control, immediate extubation, abolition of "routine" laboratory and imaging investigations, and early and aggressive postoperative patient mobilization in an integrated, multidisciplinary postthoracotomy rehabilitation program., Methods: In a retrospective controlled cohort study, data were collected for the 501 procedures performed on 311 patients (MIS group) from July 1, 2000, to June 30, 2001, and for 130 similar procedures performed on 90 similar patients under a standard general thoracic surgery ad hoc clinical program from July 1, 1998, to June 30, 1999., Results: After implementation of the clinical guideline, services expanded with a 345% increase in case volume, a 40% reduction in cost, no adverse effects, and increased referring-physician and patient satisfaction., Discussion: Significant performance improvement was realized by implementing a multidisciplinary clinical guideline for thoracic surgery that seamlessly integrated all facets of diagnosis, therapy, and rehabilitation.

Human cord blood-derived mast cells undergo apoptosis upon exposure to recombinant human (rh)IL-4 and become resistant to rhIL-4-induced apoptosis when cultured in the presence of rhIL-6. The current study extends these effects of rhIL-4 to different populations of human mast cells, namely fetal liver-derived mast cells, lung-derived mast cells, and skin-derived mast cells. Endogenous production of IL-6 appears to protect fetal liver-derived mast cells and those of the MC(T) phenotype from rhIL-4-mediated apoptosis, because neutralization of IL-6 renders these mast cells sensitive. In contrast, mast cells of the MC(TC) phenotype from skin and lung were resistant to IL-4-mediated apoptosis, even after neutralization of endogenous IL-6. MC(TC) cells were CD124(low), whereas those of the MC(T) cells were CD124(high). These observations extend the phenotypic differences between MC(T) and MC(TC) types of human mast cells to include different functional responses to IL-4.

Background: Methods to assess the six competency categories outlined by the Accreditation Council on Graduate Medical Education are essential to allow residency programs to develop reproducible evaluations of their educational curriculum. Current tools to evaluate competencies are insufficient to perform these tasks, particularly in subspecialty disciplines. The key objective of this initiative was to develop and implement an evaluative tool that would provide data to residents and program leadership regarding their performance and to provide the training program with a reliable way to assess this component of the program., Methods: Utilizing a highly customized survey tool with a group of cardiothoracic residents, we implemented a 360-degree performance assessment process based on the six Accreditation Council on Graduate Medical Education competency areas. The full spectrum of associations in a resident's sphere of interaction were surveyed (ie, supervisors, peers, direct reports, nurses, and administrative personnel). Each resident received a comprehensive report that included detailed documentation of the self-evaluation and the average rating of others by category. Each resident also received a transcript of the responses to the open-ended questions and summary of the data highlighting areas of excellence, areas for improvement, and suggested goals and recommendations. The program director received copies of all of these as well as a chart documenting the average scores on each item for the whole cohort., Results: Each resident met with the 360-degree feedback specialist and the program director to develop and commit to an action plan based on the feedback. The feedback process was repeated approximately 8 months later., Conclusions: The 360-degree feedback results provided valuable information for the residents. It also provided our program with a reproducible, quantifiable tool to assess these competencies. Combined with other instruments, the 360-degree feedback was found to be a particularly valuable instrument.

Background: Ischemia/reperfusion injury remains a limiting factor in lung transplantation. Traditional hyperkalemic preservation solutions are associated with a host of metabolic derangements. ATP-regulated potassium channel openers (PCOs) may provide an attractive alternative to traditional solutions by utilizing inherent mechanisms of ischemic preconditioning. The purpose of this study was to assess warm ischemia graft protection with pinacidil, a nonspecific PCO., Methods: An isolated recirculating blood perfused ventilated rabbit lung model was used (n = 15). No ischemia control lungs underwent immediate reperfusion (n = 5). Warm ischemia control lungs were flushed with lactated Ringers (LR), stored at 37 degrees C for 2.5 hours and then reperfused for 2 hours (n = 5). PCO protected lungs were flushed with LR + 100 micromol/L pinacidil, stored, and then reperfused (n = 5). Intermittent blood gases were taken from the pulmonary artery and left atria. Every 30 minutes, graft function was assessed with a 10-minute 100% fractional inspired oxygen concentration challenge to measure maximal gas exchange. Lung samples were graded for histologic injury and assayed for myeloperoxidase activity., Results: A mixed-models repeated measures ANOVA demonstrated a significant difference between groups. Tukey's honestly significant difference multiple comparison test demonstrated significantly improved graft function and reduced histologic injury with pinacidil protection compared with the warm ischemia controls. There was no significant difference in graft function or pathology grade between the pinacidil protected lungs and the no ischemia controls. A similar trend, although not significant, was seen in myeloperoxdiase activity., Conclusions: Potassium channel openers with pinacidil can provide pulmonary protection against warm ischemia reperfusion injury.

Background: Ischemia-reperfusion injury continues to represent a significant challenge to successful lung transplantation. Traditional pulmonary ischemic protection is performed using hypothermic hyperkalemic depolarizing solutions to reduce the metabolic demands of the ischemic organ. Measures to further reduce the effects of ischemic injury have focused on the reperfusion period. We tested the hypothesis that novel physiologic hyperpolarizing solutions-using ATP-dependent potassium channel (K(ATP)) openers-given at the induction of ischemia, will reduce cellular injury and provide superior graft function even after prolonged periods of ischemia., Methods: An isolated blood-perfused ventilated rabbit lung model was used to study lung injury. Airway, left atrial, and pulmonary artery pressures were measured continuously during the 2-h reperfusion period. Oxygenation, as a surrogate of graft function, was measured using intermittent blood gas analysis of paired left atrial and pulmonary artery blood samples. Graft function was measured by oxygen challenge technique (F(i)O(2) = 1.0). Wet-to-dry ratio was measured at the conclusion of the 2-h reperfusion period. Control (Group I) lungs were perfused with modified Euro-Collins solution (depolarizing) and reperfused immediately (no ischemia). Traditional protection lungs were perfused with modified Euro-Collins flush solution and stored for 4 h (Group II) or 18 h (Group III) at 4 degrees C before reperfusion. Novel protection (Group IV) lungs were protected with a hyperpolarizing solution containing 100 nM Aprikalim, a specific K(ATP) channel opener, added to the modified Euro-Collins flush solution and underwent 18 h of ischemic storage at 4 degrees C before reperfusion., Results: Profound graft failure was measured after 18 h of ischemic storage with traditional protection strategies (Group III). Graft function was preserved by protection with hyperpolarizing solutions even for prolonged ischemic periods (Group IV). Wet-to-dry weight ratio, airway, left atrial, and pulmonary artery pressures were not significantly different between the groups., Conclusions: We have created a model of predictable lung injury. Membrane hyperpolarization with a K(ATP) channel opener (PCO) provides superior prolonged protection from ischemia-reperfusion injury in an in vitro model of pulmonary transplantation.

Benign metastasizing leiomyoma is a rare clinical entity that has been described in several previous reports. Although the exact pathophysiology of the disease is unknown, two predominant theories exist: (1) metastasis from an existing leiomyoma (commonly seen with uterine leiomyoma) or (2) multicentric leiomyomatous growths rather than actual metastases. We present an interesting case in which several elements of the patient's history complicated the differential diagnosis.

Nissen fundoplication is the most commonly performed surgical procedure in the management of gastroesophageal reflux disease. Esophageal and gastric perforations most commonly occur in the perioperative period and carry significant morbidity. We describe a unique case of intrathoracic gastric wrap perforation and its suspected pathophysiology almost two decades after the original procedure.

Previous studies have suggested that variations in the underlying ventricular fibrillation (VF) waveform may be one of the factors responsible for the probabilistic nature of defibrillation. The heart appeared to be more susceptible to defibrillation at higher absolute VF voltages (AVFV). This study investigated in an open-chest canine model (n = 8), a newly developed system that analyzed the VF waveform in real-time, instantaneously determined the time to shock, and immediately delivered a fixed low energy DC shock. A two parameter tracking technique using a running long-term and short-term AVFV average was devised to automatically identify a high voltage peak area of the VF waveform, which has been hypothesized to represent a critical period susceptible to defibrillation. Using a DC shock estimated at the 50% success level, the performance using this technique in 58 defibrillation trials was compared to the performance of the conventional method of shocking at a fixed time (random shock method) in 62 trials. Patch size, electrode location, and discharge voltage were kept constant while VF duration, transmyocardial resistance (TMR), energy delivered, and AVFV at the point of shock were measured. Shock energy and current, TMR, and VF duration were similar with both shock methods. A significantly higher AVFV was observed for trials performed with the peak shock method (0.66 +/- 0.02 mV) as compared to trials performed with the random shock method (0.25 +/- 0.09 mV) (P < 0.003). Using lead II as the only sensing lead, the success rate was increased in 6 of 8 dogs (75%) with the new method. One animal showed identical performance, and one animal a worse performance. The overall increase in success rate was 24% using a single ECG lead (range 0%-100%; P < 0.04). Our data document that using this algorithm a period of high VF voltage can be detected in real-time. The improved success in the majority of animals supports the hypothesis that a critical period susceptible to defibrillation exists during VF. However, the high AVFV detected using a single ECG lead did not translate to an improved success rate in all animals. This suggests that other factors in addition to the VF voltage measured on a single lead of the ECG are important in characterizing this critical period.

Cardioplegic solutions that arrest the heart at or near the resting membrane potential may provide better myocardial protection than standard depolarizing hyperkalemic cardioplegia by reducing both metabolic demand and harmful transmembrane ion fluxes. This hypothesis was investigated in an isolated, blood-perfused, rabbit heart Langendorff model during 30 minutes of normothermic global ischemia. Hyperpolarized cardiac arrest induced by aprikalim, an opener of adenosine triphosphate-dependent potassium channels, was compared with hyperkalemic depolarized arrest and with unprotected global ischemia. Left ventricular pressure was recorded over a wide range of balloon volumes before ischemia and 30 minutes after reperfusion. End-diastolic pressure versus balloon volume data were fitted to a two-coefficient exponential relationship. Changes in the diastolic compliance of the left ventricle were assessed by comparison of preischemic and postischemic coefficients within each cardioplegia group. Postischemic recovery of developed pressure was used to assess changes in left ventricular systolic function. The tissue water content of each heart was also determined. Myocardial protection with aprikalim resulted in better postischemic recovery of developed pressure (90% +/- 9%) than either protection with hyperkalemic cardioplegia (73% +/- 11%) or no protection (62% +/- 9%). Myocardial tissue water content in hearts protected with hyperkalemic cardioplegia (77.4% +/- 1.4%) was less than the tissue water content of either unprotected hearts (79.4% +/- 1.2%) or hearts protected with aprikalim (78.7% +/- 0.9%). Despite these differences, neither hyperkalemic cardioplegia (p = 0.15) nor aprikalim cardioplegia (p = 0.30) was associated with a significant postischemic decrease in ventricular compliance. By contrast, unprotected global ischemia was associated with a significant decrease in ventricular compliance (p < 0.001).

Background: Mounting clinical and experimental evidence suggests that postoperative myocardial dysfunction is a frequent consequence of surgical global ischemia and reperfusion, despite our modern techniques of myocardial protection. The ubiquitous use of hyperkalemic depolarizing solutions in all forms of cardioplegia may be partly responsible for this phenomenon because of the known ongoing metabolic processes and damaging transmembrane ionic fluxes that occur at depolarized membrane potentials. Cardiac arrest at hyperpolarized potentials, the natural resting state of the heart, may avoid the shortcomings of depolarized arrest and provide an alternative means of myocardial protection., Methods: An adenosine triphosphate-sensitive potassium channel opener, aprikalim, was used to induce hyperpolarized arrest. Aprikalim was able to produce sustained and reproducible electromechanical arrest that was reversible by reperfusion., Results: In isolated heart models, when compared with depolarized hyperkalemic arrest, hyperpolarized arrest afforded better protection from global normothermic ischemia and resulted in better postischemic recovery of function upon reperfusion. Preliminary studies in a porcine cardiopulmonary bypass model also have revealed that hyperpolarized arrest can be achieved in a model more closely approximating the clinical setting, and can effectively protect the heart during normothermic surgical global ischemia., Conclusions: Hyperpolarized cardiac arrest may offer an effective alternative to traditional potassium arrest.

Stretch-activated channels (SAC) are postulated to regulate cell volume. While this hypothesis is appealing, direct evidence is lacking. Using digital video microscopy, we found that pharmacological blockade of SACs alters the cell volume of isolated rabbit ventricular myocytes during hypoosmotic stress. Under control conditions, relative cell volume increased from 1.0 to 1.311 +/- 0.019 after 10 min in 195 mosmol/l solution. The cation SAC blocker gadolinium (Gd3+; 10 microM) reduced the amount of swelling in hypoosmotic solution by 24% and induced a regulatory volume decrease otherwise not observed. In contrast, the anion SAC blocker 9-anthracene carboxylic acid (9-AC; 1 mM) increased swelling by 44% under the same conditions. Based on the direction of SAC currents, Gd3+ and 9-AC are expected to have opposite effects on cell volume. Furthermore, Gd3+ and 9-AC changed cell volume by only approximately 2% in isosmotic solutions when SACs are expected to be closed. This supports the idea that Gd3+ and 9-AC affect stretch-activated transport processes. In contrast, omitting bath Ca2+ did not alter cell volume under iso- or hypoosmotic conditions suggesting stretch-activated Ca2+ influx is not important in setting cell volume. Not all channels can affect cell volume. Opening ATP-sensitive K+ channels with aprikalim (100 microM) or blocking them with glibenclamide (1 microM) did not alter cell volume under isosmotic or hypoosmotic conditions. These data support the idea that SACs are involved in cardiac cell volume regulation.

Myocardial protection strategies use cardioplegic solutions to reduce the injury induced by surgical ischemia and reperfusion. However, there is a high incidence of electrophysiologic abnormalities after cardioplegic arrest. A computerized epicardial mapping system in a porcine cardiopulmonary bypass model was used to measure the electrophysiologic consequences of different myocardial protection techniques. Both warm and cold, crystalloid and blood cardioplegic solutions were compared. The effects of hypothermia and prolonged cardiopulmonary bypass were examined in a control group that underwent a 2-hour period of hypothermia without cardioplegia or aortic cross-clamping, followed by 2 hours of normothermic reperfusion. Isochronous activation maps, unipolar electrograms, ventricular refractory periods, and pacing thresholds were measured before cardioplegic arrest and during reperfusion. Compared with the control group, crystalloid cardioplegia, but not blood cardioplegia, was accompanied by large changes in the pattern of ventricular activation and by persistent (> 2 hours) and significant slowing of the time required for complete ventricular activation. This was not the result of hypoxia. Moreover, the effective refractory period and the pacing threshold were unchanged by any cardioplegia. Our data suggest that crystalloid cardioplegia increases myocardial resistance to current flow leading to a derangement of electrical impulse propagation that may underlie arrhythmogenesis.

There is clinical evidence that myocardial stunning is a frequent sequela of surgical global ischemia, despite our modern techniques of myocardial protection. The ubiquitous usage of hyperkalemic depolarizing solutions in all forms of cardioplegia may be partly responsible for this phenomenon because of the known ongoing metabolic requirements and damaging transmembrane ionic fluxes that occur at depolarized membrane potentials. Cardiac arrest at hyperpolarized potentials, the natural resting state of the heart, may avoid the shortcomings of depolarized arrest and provide an alternative means of myocardial protection. To test this hypothesis, a potassium channel opener, aprikalim, was used to induce hyperpolarized arrest in an isolated rabbit heart model. Aprikalim was able to produce sustained and reproducible electromechanical arrest that was reversible by reperfusion. When compared with depolarized hyperkalemic arrest, hyperpolarized arrest afforded better protection after short 20-minute periods of global ischemia and resulted in less myocardial stunning. Moreover, aprikalim was able to significantly prolong the time to ischemic contracture and improve functional recovery after the onset of ischemic contracture when compared with either traditional hyperkalemic cardioplegia or no cardioplegia at all. There was a dose dependence to the protective effect of aprikalim. Preliminary studies in the intact porcine cardiopulmonary bypass model also have revealed that hyperpolarized arrest can effectively protect the heart during surgical global ischemia.

In order to examine the effects of ventricular distention on the unipolar electrogram (UEG), an isolated rabbit heart modified Langendorff preparation was utilized. Left ventricular (LV) volume was adjusted using ionically permeable (PB = 9 hearts) or ionically impermeable balloons (IB = 4 hearts). LV UEGs, LV end-diastolic pressure (EDP), and LV minor axis dimension (MAD), as measured by ultrasonic transducers, were recorded. Three hundred twenty-five electrograms were digitized and analyzed with custom-designed software. In the PB group, a significant inverse linear relationship was found between UEG amplitude and changes in MAD (P < 0.0001). For each animal, this relationship had an R value > 0.8 and a P value < 0.0001. There was also a significant inverse linear relationship between UEG slope and changes in MAD (P < 0.01). UEG amplitude and slope also exhibited a significant inverse relationship to changes in LV EDP, which were best described by a third order polynomial function. In the IB group, no significant relationship was found between either UEG amplitude or slope and MAD or EDP. In this study, intracavitary volume exerted a profound and significant influence on UEG amplitude and slope. This effect was due to increases in conductive intraventricular volume and not to myocardial stretch.

Introduction: Significant species-, tissue-, and age-dependent differences have been described for the L-type calcium current (ICa). Therefore, extrapolation of data obtained from the many animal models to human cardiac physiology is difficult. In this study, we have characterized the voltage-dependent properties of ICa from pediatric and adult, atrial and ventricular human heart tissue., Methods and Results: ICa was measured in single human heart muscle cells using the "whole cell," voltage clamp method. Single myocytes were isolated from myocardial specimens obtained intraoperatively from both pediatric and adult patients (ages 3 months to 75 years) undergoing cardiac surgery. Cells obtained for these experiments appeared to be healthy; the resting potential was between -80 and -85 mV. The action potential shape and duration and current-voltage relationship for ICa were similar to that reported by others for human heart cells. The steady-state activation variable, d infinity, was found to be similar in both pediatric atrial and ventricular cells but shifted approximately 5 mV negative in the adult atrial and ventricular cells. ICa of all cells displayed biexponential inactivation and steady-state inactivation was incomplete at positive potentials (steady-state inactivation curves turned up at positive potentials) consistent with inactivation arising from voltage-dependent and calcium-dependent processes as reported in heart cells from many species. The potential of maximal inactivation was more negative for adult cells (around -10 mV) than pediatric cells (around 0 mV). Estimates of the calcium "window" current, using a modified Hodgkin-Huxley model, could explain measured differences in action potential shape and duration., Conclusion: Human cardiac ICa can be investigated using whole cell, voltage clamp methods and a modified Hodgkin-Huxley model. Quantitative characterization of many of the properties of ICa in human heart tissue suggests that important species differences do exist and that further investigations are required to characterize the dependence of inactivation on [Ca2+]i in human heart cells. Since the array of characteristics of ICa in different species varies, the study of human myocardial cells per se continues to be important when examining human cardiac physiology.

Background: Hyperkalemic depolarized cardiac arrest has been the cornerstone of myocardial protection during cardiac surgery for more than 30 years. Many of the advances in myocardial protection seek to minimize the cellular damage and to reduce the ongoing metabolic processes occurring as a direct consequence of the depolarized state. Ideally, cardiac arrest at hyperpolarized cellular membrane potentials--the natural resting state of the heart--will meet all the requirements of modern cardioplegia, namely, electromechanical asystole and cardiac relaxation, while preserving the vital integrity of the heart itself., Methods and Results: To determine whether activation of adenosine triphosphate-sensitive potassium channels by pharmacologic agents could produce hyperpolarized cardiac arrest, we tested the ability of aprikalim, a known adenosine triphosphate-sensitive potassium channel opener, to arrest the intact beating heart. In a normothermic (37 degrees C) isolated rabbit heart preparation, aprikalim was found to rapidly shorten the action potential duration and produce cardiac asystole that was maintained during 20 minutes of "no-flow" global ischemia without a rise in end-diastolic pressure. Cardiac rhythm and function were fully restored by reperfusion alone (developed pressure was 100.6% +/- 7.9% of prearrest value after 30 minutes of reperfusion). In contrast, 20 minutes of unprotected normothermic global ischemia resulted in a 2.7 +/- 0.55 mmHg rise in end-diastolic pressure and only 58.2% +/- 3.8% recovery of developed pressure after 30 minutes of reperfusion. By way of comparison, 20 minutes of standard hyperkalemic depolarized normothermic rest was accompanied by a 1.2 +/- 0.6 mmHg rise in end-diastolic pressure and only 80.8% +/- 2.6% recovery of developed pressure after 30 minutes of reperfusion. To directly compare hyperkalemic depolarized cardiac arrest to hyperpolarized cardiac arrest induced by potassium channel openers and to better define the characteristics of such hyperpolarized arrest, we studied a fixed (4 mmHg rise in end-diastolic pressure--contracture) ischemic injury model. The time to development of the contracture was prolonged by hyperkalemic arrest (35.8 +/- 1.7 minutes) and significantly more so by hyperpolarized arrest (47.0 +/- 3.3 minutes) when compared with that of unprotected hearts (24.0 +/- 1.2 minutes). Moreover, aprikalim resulted in significantly better postischemic recovery of function (developed pressure was 69.0% +/- 6.7% of prearrest value after 30 minutes of reperfusion) than after no cardioplegia (45.4% +/- 7.5%) or standard hyperkalemic cardioplegia (44.3% +/- 5.7%)., Conclusions: Pharmacologic activation of adenosine triphosphate-sensitive potassium channels can result in predictable and sustainable hyperpolarized cardiac arrest that is reversible by reperfusion. This method of myocardial protection was found to fully preserve cardiac electromechanical function after a 20-minute period of global normothermic ischemia. Furthermore, hyperpolarized arrest induced by potassium channel openers significantly prolonged the period to the development of contracture and afforded a significantly better postischemic recovery of function than obtained in either hearts protected with hyperkalemic depolarized arrest or those not protected by any form of cardioplegia.

While the development of pharmacological cardioplegic solutions for myocardial protection during cardiopulmonary bypass (CPB) have significantly lengthened the safe operating time for cardiac surgical procedures, the introduction of hypothermic hyperkalemic cardioplegia (CPG) has markedly increased the incidence of postoperative arrhythmias and conduction abnormalities. Using a customized modification of a computerized mapping system, we have developed a large animal porcine model of CPB that is exquisitely sensitive to the electrophysiological (EP) derangements imposed by ischemia and cardiac arrest. This model is able to measure spatial and temporal parameters of ventricular activation with high resolution, using an array of up to 84 epicardial electrodes that can be reproducibly placed on the surface of the heart utilizing known epicardial anatomical markers (e.g., coronary arteries). With this system we have measured the spectrum of clinically observed EP disturbances caused by CPG, from slowed intraventricular conduction to complete heart block. Compared to the control group of hypothermia alone, 2 hours of crystalloid CPG arrest had a significant slowing effect on ventricular activation (p < 0.05). CPG was accompanied, in each animal, by profound changes in the spatial distribution of ventricular activation and persistent slowing of ventricular activation. Traditional EP parameters of effective refractory period and pacing threshold were unchanged by CPG. Smaller temporal and spatial changes were observed in the control group, but were always reversed by 90 minutes of warm reperfusion. We conclude that CPG induces injury of the specialized conducting system and, to a lesser degree, the myocardium. This model will afford us the opportunity to test new methods of CPG to further improve myocardial preservation during CPB.

Experimental data do not support the idea that excitation-contraction coupling in heart muscle can be explained by a simple calcium-induced calcium release mechanism alone or a simple voltage-dependent calcium release mechanism alone. Our data on excitation-contraction coupling combined with the results of others suggest the need to either develop more complex and more sophisticated single-mechanism models, or to establish dual-control models.

1. Calcium current (ICa) was recorded in single rat heart cells at two periods during development: (1) at 2-7 days post-partum (neonatal), and (2) at 6-8 weeks (adult). 2. We measured both transient and steady-state components of ICa and could describe ICa in terms of the steady-state activation (d infinity) and inactivation (f infinity) parameters, the channel reversal potential (Echannel) and a relative conductance parameter, gr. 3. In adult single cells, the application of ryanodine (10 microM), an agent known to alter the function of the sarcoplasmic reticulum (SR), abolished contraction rapidly and increased ICa. Ryanodine also produced a 13 mV shift in f infinity towards more positive potentials and altered its slope, while producing a small increase in gr but no effect on d infinity. In neonatal single cells, ryanodine (10 microM) had no significant effect on contraction, ICa, d infinity, f infinity, or gr. Caffeine (10 mM), a less specific agent widely used to investigate sarcoplasmic reticulum function, had actions similar to those of ryanodine. 4. In adult myocytes, when EGTA (10 or 20 mM) or bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA, 10 mM) were included in the pipette solution, contractions were rapidly abolished, while a small (4 mV) shift of f infinity to more positive potentials was seen. A large additional shift of f infinity was observed when ryanodine (10 microM) was added to the superfusion solution in the continued presence of EGTA or BAPTA. The alterations of ICa in EGTA (or BAPTA) plus ryanodine were the same as those seen in ryanodine alone. In neonatal cells, in contrast, when EGTA or BAPTA were included in the pipette solution we observed only a small effect on f infinity and the application of ryanodine had no effect. 5. Electron micrographs of our preparations show that the dissociated adult cells have sharp sarcolemmal borders, fully developed sarcomeres with T-tubules and sarcoplasmic reticulum membranes. In contrast, the neonatal cells that we use have few of these intracellular structures. Our observations in these preparations are consistent with the work of others (e.g. Penefsky, 1974; Hirakow & Gotoh, 1975; Ishikawa & Yamada, 1975; Legato, 1975; Hoerter, Mazet & Vassort, 1981). 6. Our data suggest that fully developed sarcoplasmic reticulum in rat heart cells can affect ICa.(ABSTRACT TRUNCATED AT 400 WORDS)

The effects of increased protein kinase C activity were studied in neonatal rat myocytes grown in primary culture. The changes in mechanical and electrical behavior, as well as protein phosphorylation, that followed the apparent activation of protein kinase C by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) were examined. As spontaneous beating frequency was increased minimally by 10 nM TPA and by 100% with 85 nM TPA, shortening amplitude, shortening velocity, and relaxation velocity decreased concomitantly. In contrast, 4-alpha-phorbol-12,13-didecanoate (alpha-PDD), which does not activate protein kinase C, had no effect on beating behavior at 800 nM. In voltage-clamped single myocytes, both steady-state and transient components of the cadmium-sensitive calcium current were increased by the addition of TPA (65 nM). Neither the time constant for the inactivation of the transient component of this calcium current nor the reversal potential was altered by TPA. The phosphorylation state of a discrete set of proteins, with apparent molecular weights of 32 and 83 kDa, was enhanced when TPA was added to intact myocytes. Angiotensin II enhances the phosphorylation state of the same set of proteins as observed with TPA. We conclude that activation of protein kinase C can modify mechanical behavior and increase L-type Ca2+ channel activity in cultured neonatal rat ventricular myocytes. The remarkable similarity in mechanical, electrical, and protein phosphorylation responses of cultured neonatal myocytes following TPA or angiotensin II application indicate that protein kinase C may mediate the action of angiotensin II.

Muscarinic receptors found in the N1E-115 mouse neuroblastoma cell line were tested for their ability to mediate stimulation of phosphatidylinositol (PI) turnover. This study was facilitated by the development of a new solvent system (acetone:butanol:acetic acid:water, 3:5:1:1) for the rapid and consistent separation of PI by one-dimensional thin-layer chromatography. Cholinergic stimulation caused as much as a 680% increase in the incorporation of 32P into PI. Enhanced incorporation of 32P into PI could be measured as early as 4 min after stimulation began. By 20 min, the rate of incorporation by stimulated cells had decreased to that of unstimulated cells, indicating desensitization. The magnitude of the response was dependent on the extent of receptor occupancy, and the response elicited by a saturating dose of carbamylcholine was blocked completely by 10(-7) M atropine, a specific muscarinic antagonist. Chronic stimulation, known to cause a loss of receptor binding sites, led to a 90% decrease in the maximum response even after a 40-min withdrawal period. Replacement of Na+ ions in the medium with choline or K+ severely impaired the ability of the cells to incorporate added 32P into PI (90 and 50%, respectively). Removal of the putative second messenger Ca2+ for short periods of time by the addition of excess EGTA did not alter either basal or muscarinic-stimulated PI turnover.

We have investigated the links between electrical excitation and contraction in mammalian heart muscle. Using isolated single cells from adult rat ventricle, a whole-cell voltage-clamp technique and quantitative fluorescence microscopy, we have measured simultaneously calcium current (ICa) and [Ca2+]i (with fura-2). We find that the voltage-dependence of ICa and the [Ca2+]i-transient and the dependence of [Ca2+]i-transient on depolarization-duration cannot both be readily explained by a simple calcium-induced Ca-release ('CICR') mechanism. Additionally, we find that when [Ca2+]i and [Na+]i are at their diastolic levels, activation of the Na-Ca exchange mechanism by depolarization does not measurably trigger the release of Ca2+i. Finally, measuring ICa in adult and neonatal rat heart cells and using the alkaloid ryanodine, we have carried out complementary experiments. These experiments show that there may be an action of ryanodine on ICa that is independent of [Ca2+]i and independent of a direct action of the alkaloid on the calcium channel itself. Along with experiments of others showing that ryanodine binds to the sarcoplasmic reticulum calcium-release channel/spanning protein complex, our data suggests a model to explain our findings. The model links the calcium channels responsible for ICa to the sarcoplasmic reticulum by means of one or more of the spanning protein(s). Information from the calcium channel can be communitated to the sarcoplasmic reticulum by this route and, presumably, information can move in the opposite direction from the sarcoplasmic reticulum to the calcium channel.

The effect of angiotensin II on cultured neonatal rat heart myocytes was studied by measuring changes in cell length, the magnitude and kinetics of the calcium current, and changes in cyclic adenosine 3',5'-monophosphate (cAMP) and phosphoinositide metabolism. Spontaneous beating frequency of multicellular networks was increased by angiotensin II with a maximal increase of 100% above control values at concentrations of 5 nM or greater. The half-maximal response occurred at 0.6 nM angiotensin II. Shortening amplitude, shortening velocity, and relaxation velocity decreased concomitantly with the increasing contractile rate. In voltage-clamped single myocytes, both steady-state and transient components of the calcium current were increased by the addition of angiotensin II. Angiotensin II had no effect on either control or isoproterenol-stimulated adenylate cyclase activity in myocyte membranes. Neither the basal levels nor the isoproterenol-stimulated cAMP accumulation in intact cells was affected by addition of hormone. In myocytes labeled with [3H]inositol, angiotensin II stimulated the formation of [3H]inositol phosphates. One minute after addition of 5 nM angiotensin II, inositol monophosphate and inositol bisphosphate levels were increased to 73% and 99%, respectively, above control values and remained elevated at 10 minutes. Inositol trisphosphate levels were not significantly different from control values at either time point. Nifedipine (10 microM) had no effect on angiotensin II-induced increases in [3H]inositol phosphates. We conclude that the increases in both spontaneous beating rate and calcium current in angiotensin II-stimulated cultured neonatal heart cells are not dependent on cAMP or inositol trisphosphate levels but may involve sustained phosphoinositide hydrolysis.

1. Calcium currents (ICa) from neonatal rat ventricular heart muscle cells grown in primary culture were examined using the 'whole-cell' voltage-clamp technique (Hamill, Marty, Neher, Sakmann & Sigworth, 1981). Examination of ICa was limited to one calcium channel type, 'L' type (Nilius, Hess, Lansman & Tsien, 1985), by appropriate voltage protocols. 2. We measured transient and steady-state components of ICa, and could generally describe ICa in terms of the steady-state activation (d infinity) and inactivation (f infinity) parameters. 3. We observed that the reduction of ICa by the calcium channel antagonist D600 can be explained by both a shift of d infinity to more positive potentials as well as a slight reduction of ICa conductance. D600 did not significantly alter either the rate of inactivation of ICa or the voltage dependence of f infinity. 4. The calcium channel modulator BAY K8644 shifted both d infinity and f infinity to more negative potentials. Additionally, BAY K8644 increased the rate of inactivation at potentials between +5 and +55 mV. Furthermore, BAY K8644 also increased ICa conductance, a change consistent with a promotion of 'mode 2' calcium channel activity (Hess, Lansman & Tsien, 1984). 5. We conclude that, as predicted by d infinity and f infinity, there is a significant steady-state component of ICa ('window current') at plateau potentials in neonatal rat heart cells. Modulation of the steady-state and transient components of ICa by various agents can be attributed both to specific alterations in d infinity and f infinity and to more complicated alterations in the mode of calcium channel activity.

The British Regional Heart Study seeks to define risk factors for cardiovascular disease, to examine their interrelationships, and to explain the geographic variations in cardiovascular disease in Britain. A clinical survey of men aged 40-59 in 24 British towns was carried out and preliminary data from the survey analysed. On a town basis cardiovascular mortality was associated with mean systolic blood pressure and the prevalence of heavy cigarette smoking and heavy alcohol consumption. No such association was seen for body mass index or mean serum total cholesterol or high-density-lipoprotein cholesterol concentration. Cigarette smoking and alcohol intake and, to a less degree, systolic blood pressure were related to the social class (percentage of manual workers) of a town, and these factors may determine to some extent the increased risk of cardiovascular disease in manual workers. Blood pressure in individual subjects was affected predominantly by age, body mass index, and alcohol intake. Body mass index appeared to affect blood pressure to a greater extent than alcohol intake and did so with a consistent and positive linear trend. Nevertheless, the differences between towns in mean blood pressure readings appeared to be more closely associated with variations in the prevalence of heavy drinking than with variations in body mass index. Alcohol intake and body mass index explained only a part of the striking differences between towns in mean blood pressure readings, and some important "town"factors remained unexplained.

Cross-sectional-type reference values for weight attained are described for village children under five years in rural Lesotho (formerly Basutoland). Weight measurements derive from observations on 1317 children attending an Under-Fives clinic; it is estimated that 60-70% of the children under five in the catchment area were represented. 4585 weighings on boys and 4826 weighings for girls are included in the analysis. Figures of weight-for-age of boys and girls are given separately as centile distributions suitable for use on Growth Charts. Lesotho 50 centile approximates to 3 centile of British children and slightly exceeds 80% Harvard standard. Weight attained for age is similar, in both sexes, to reports from other less-priviledged urban and rural areas, emphasizing the relative importance of environmental as compared to genetic influences in determining weight-for-age in early childhood. It is suggested that the construction of locally-derived growth reference values is both appropriate and practicable.

Histamine was found to stimulate the turnover of phosphatidylinositol (PI) in cultures of neuron-like NE-115 cells. Turnover was measured by increased production of [3H]inositol phosphates (breakdown) and by accelerated incorporation of 32P into PI (resynthesis). Data were consistent with hydrolysis of polyphosphoinositides being the initial event in receptor-stimulated PI turnover. This response to histamine desensitized within 10 min. Receptor systems for histamine and acetylcholine were tested for possible interactions: PI turnover in response to dual stimulation was approximately equal to the sum of the individual responses while prior desensitization of the acetylcholine receptor system had no effect on subsequent stimulation of the histamine receptor system. These results are consistent with the hypothesis that components of acetylcholine and histamine receptor systems responsible for PI turnover are autonomously organized and regulated. and regulated.