Molecular and morphological variability within the Aphidius colemani group with redescription of Aphidius platensis Brethes (Hymenoptera: Braconidae: Aphidiinae).

We have identified the following three taxa related to the Aphidius colemani species group, which are important biological control agents: Aphidius colemani, Aphidius transcaspicus and Aphidius platensis. Using partial sequences of the mitochondrial cytochrome oxidase subunit I (mtCOI) gene and geometric morphometric analysis of the forewing shape, we have explored the genetic structure and morphological variability of the A. colemani group from different aphid host/plant associations covering a wide distribution area. The topology of the maximum parsimony and maximum likelihood trees were identical with 98-100% bootstrap support, clustering A. colemani, A. platensis and A. transcaspicus into separate species. The distances among the taxa ranged from 2.2 to 4.7%, which is a common rate for the between-species divergence within the subfamily Aphidiinae. Differences in the shape of the forewing investigated within the biotypes of A. colemani group are congruent with their genetic diversification. Both A. platensis and A. colemani share a common host range pattern, and it would be interesting to estimate and compare the role of these two species in future biological control strategies against aphids of economic importance. Our results indicate that 'genetic screening' is a reliable approach for identification within the A. colemani group. The high variation in the wing shape among species, including a significant divergence in the wing shape among specimens that emerged from different hosts, makes the forewing shape and wing venation less reliable for species determination. Aphidius platensis is diagnostified and redescribed, and the key for the A. colemani group is presented.

Nomogram for predicting survival after first-line anti-PD-1-based immunotherapy in unresectable stage IV melanoma: a multicenter international study.

BACKGROUND: The introduction of anti-programmed cell death protein 1 (PD-1) immunotherapy has revolutionized the treatment landscape for melanoma, enhancing both response rates and survival outcomes in patients with advanced stages of the disease. Despite these remarkable advances, a noteworthy subset of patients (40%-60%) does not derive advantage from this therapeutic approach. This study aims to identify key predictive factors and create a user-friendly predictive nomogram for stage IV melanoma patients receiving first-line anti-PD-1-based immunotherapy, improving treatment decisions. MATERIALS AND METHODS: In this retrospective study, we included patients with unresectable stage IV melanoma who received first-line treatment with either anti-PD-1 monotherapy or anti-PD-1 plus anti-cytotoxic T-lymphocyte associated protein 4 between 2014 and 2018. We documented clinicopathological features and blood markers upon therapy initiation. By employing the random survival forest model and backward variable selection of the Cox model, we identified variables associated with progression-free survival (PFS) after the first-line anti-PD-1-based treatment. We developed and validated a predictive nomogram for PFS utilizing the identified variables. We assessed calibration and discrimination performance metrics as part of the evaluation process. RESULTS: The study involved 719 patients, divided into a training cohort of 405 (56%) patients and a validation cohort of 314 (44%) patients. We combined findings from the random survival forest and the Cox model to create a nomogram that incorporates the following factors: lactate dehydrogenase (LDH), S100, melanoma subtype, neutrophil-to-lymphocyte ratio (NLR), body mass index, type of immune checkpoint inhibitor, and presence of liver or brain metastasis. The resultant model had a C-index of 0.67 in the training cohort and 0.66 in the validation cohort. Performance remained in different patient subgroups. Calibration analysis revealed a favorable correlation between predicted and actual PFS rates. CONCLUSIONS: We developed and validated a predictive nomogram for long-term PFS in patients with unresectable stage IV melanoma undergoing first-line anti-PD-1-based immunotherapy.

Robot- and computer-assisted craniotomy (CRANIO): from active systems to synergistic man-machine interaction.

Computer and robot assistance in craniotomy/craniectomy procedures is intended to increase precision and efficiency of the removal of calvarial tumours, enabling the preoperative design and manufacturing of the corresponding implant. In the framework of the CRANIO project, an active robotic system was developed to automate the milling processes based on a predefined resection planning. This approach allows for a very efficient milling process, but lacks feedback of the intra-operative process to the surgeon. To better integrate the surgeon into the process, a new teleoperated synergistic architecture was designed. This enables the surgeon to realize changes during the procedure and use their human cognitive capabilities. The preoperative planning information is used as guidance for the user interacting with the system through a master-slave architecture. In this article, the CRANIO system is presented together with this new synergistic approach. Experiments have been performed to evaluate the accuracy of the system in active and synergistic modes for the bone milling procedure. The laboratory studies showed the general feasibility of the new concept for the selected medical procedure and determined the accuracy of the system. Although the integration of the surgeon partially reduces the efficiency of the milling process compared with a purely active (automatic) milling, it provides more feedback and flexibility to the user during the intra-operative procedure.

Theoretical study of nitrodibenzofurans: A possible relationship between molecular properties and mutagenic activity.

In this study we present a theoretical investigation of the molecular properties of nitrodibenzofurans (NDFs) and dinitrodibenzofurans (DNDFs) and their relation to mutagenic activity. Equilibrium geometries, relative energies, vertical ionization potentials (IP), vertical electron activities (EA), electronic dipole polarizabilities, and dipole moments of all NDFs and three DNDFs calculated by Density Functional Theory (DFT) methods are reported. The Ziegler/Rauk Energy Decomposition Analysis (EDA) is employed for a direct estimate of the variations of the orbital interaction and steric repulsion terms corresponding to the nitro group and the oxygen of the central ring of NDFs. The results indicate differences among NDF isomers for the cleavage of the related bonds and steric effects in the active site. The results show a good linear relationship between polarizability (<α>), anisotropy of polarizability (Δα), the summation of IR intensities (ΣIIR) and the summation of Raman activities (ΣARaman) over all 3N-6 vibrational modes and experimental mutagenic activities of NDF isomers in Salmonella typhimurium TA98 strain. The polarizability changes with respect to the νsNO+CN vibrational mode are in correlation with the mutagenic activities of NDFs and suggest that intermolecular interactions are favoured along this coordinate.

Papillary muscle traction in mitral valve prolapse: quantitation by two-dimensional echocardiography.

Previous angiographic observations in patients with mitral valve prolapse have suggested that superior leaflet displacement results in abnormal superior tension on the papillary muscle tips that causes their superior traction or displacement. It has further been postulated that such tension can potentially affect the mechanical and electrophysiologic function of the left ventricle. The purpose of this study was to confirm and quantitate this phenomenon noninvasively by using two-dimensional echocardiography to determine whether superior displacement of the papillary muscle tips occurs and its relation to the degree of mitral leaflet displacement. Directed echocardiographic examination of the papillary muscles and mitral anulus was carried out in a series of patients with classic mitral valve prolapse and results were compared with those in a group of normal control subjects. Distance from the anulus to the papillary muscle tip was measured both in early and at peak ventricular systole. In normal subjects, this distance did not change significantly through systole, whereas in the patient group it decreased, corresponding to a superior displacement of the papillary muscle tips toward the anulus in systole (8.5 +/- 2.6 vs. 0.8 +/- 0.7 mm; p less than 0.0001). This superior papillary muscle motion paralleled the superior displacement of the leaflets in individual patients (y = 1.0x + 0.8; r = 0.93) and followed a similar time course.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of orifice geometry on the shape of jets: an in vitro Doppler color flow study.

To investigate the influence of orifice geometry on the three-dimensional shape of jets, an in vitro Doppler color flow study was performed. Jets were formed by discharging blood through round orifices and through orifices with major/minor axis ratios of 2:1, 3:1 and 5:1. These were repeated with orifice areas of 0.1, 0.3 and 0.5 cm2. For turbulent and laminar jets formed by these orifices, Doppler color flow images were obtained from two orthogonal scanning planes aligned with the major and minor orifice axes. Jet width was measured at 1 cm intervals from 0 to 5 cm from the orifice and used to calculate jet eccentricity (ratio of major to minor axis widths) and the rate of divergence of the jet walls. Jets were observed to diverge more rapidly along walls aligned with the orifice minor axis rather than along the major axis. This differential spreading led to the development of circular symmetry at a short distance from the orifice. Jet divergence (theta) occurred more rapidly for turbulent jets and for jets formed by larger orifices: theta (zero) = 0.80 + 6.3.A + 7.0.T + 0.47.E-OR (r = 95, p less than 0.0001, n = 48), where A is orifice area (cm2); T is 0 for laminar jets, 1 for turbulent jets and E-OR combines orifice eccentricity and scanning orientation, ranging from -5 for 5:1 orifices imaged along the major axis, 0 for circular orifices to 5 for 5:1 orifices imaged along the minor axis. Within the jet, eccentricity decayed approximately exponentially with distance from the orifice, more rapidly for turbulent jets, more slowly for the larger and more eccentric orifices.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of partial left ventriculectomy on left ventricular performance in patients with nonischemic dilated cardiomyopathy.

OBJECTIVES: This study sought to assess the effects of partial left ventriculectomy (PLV) on left ventricular (LV) performance in a series of consecutive patients with nonischemic dilated cardiomyopathy. BACKGROUND: Reduction of LV systolic function in patients with heart failure is associated with an increase of LV volume and alteration of its shape. Recently, PLV, a novel surgical procedure, was proposed as a treatment option to alter this process in patients with dilated cardiomyopathy. METHODS: We studied 19 patients with severely symptomatic nonischemic dilated cardiomyopathy, before and 13+/-3 days after surgery, and 12 controls. Single-plane left ventriculography with simultaneous measurements of femoral artery pressure was performed during right heart pacing. RESULTS: The LV end-diastolic and end-systolic volume indexes decreased after PLV (from 169 to 102 ml/m2, and from 127 to 60 ml/m2, respectively, p < 0.0001 for both). Despite a decrease in LV mass index (from 162 to 137 g/m2, p < 0.0001), there was a significant decrease in LV circumferential end-systolic and end-diastolic stresses (from 277 to 159 g/cm2, p < 0.0001 and from 79 to 39 g/cm2, p = 0.0014, respectively). Ejection fraction improved (from 24% to 41%, p < 0.0001); the stroke work index remained unchanged. CONCLUSIONS: The PLV improves LV performance by a dramatic reduction of ventricular end-systolic and end-diastolic stresses. Further studies are needed to assess whether this effect is sustained during long-term follow-up and to define the role of PLV in the treatment of patients with dilated cardiomyopathy.

Early changes in left ventricular function in chronic asymptomatic alcoholics: relation to the duration of heavy drinking.

OBJECTIVES: This study sought to assess preclinical cardiac abnormalities in chronic alcoholic patients and possible differences among alcoholics related to the duration of heavy drinking. BACKGROUND: Chronic excessive alcohol intake has been reported as a possible cause of dilated cardiomyopathy. However, before the appearance of severe cardiac dysfunction, subtle signs of cardiac abnormalities may be identified. METHODS: We studied 30 healthy subjects (age 44 +/- 8 years) and 89 asymptomatic alcoholics (age 45 +/- 8 years, p = NS) divided into three groups, with short (S, 5-9 years, n = 31), intermediate (I, 10-15 years, n = 31) and long (L, 16-28 years, n = 27) duration of alcoholism. Transmitral early (E) and late (A) Doppler flow velocities, E/A ratio, deceleration time of E (DT) and isovolumic relaxation time (IVRT) were obtained. Left ventricular (LV) wall thickness and volumes were also determined by echocardiography, and LV mass and ejection fraction (EF) were calculated. RESULTS: The alcoholics had prolonged IVRT (92 +/- 11 vs. 83 +/- 7 ms, p < 0.001), longer DT (180 +/- 20 vs. 170 +/- 10 ms, p < 0.01), smaller E/A (1.25 +/- 0.34 vs. 1.40 +/- 0.32, p < 0.05), larger LV volumes (73 +/- 8 vs. 65 +/- 7 ml/m2, p < 0.001 for end-diastolic volume index; 25 +/- 4 vs. 21 +/- 2 ml/m2, p < 0.001 for end-systolic volume index), higher LV mass index (92 +/- 14 vs. 78 +/- 8 g/m2, p < 0.001) and thicker posterior wall (9 +/- 1 vs. 8 +/- 1 mm, p < 0.001). Ejection fraction did not differ between the two groups (66 +/- 4 vs. 67 +/- 2%). Deceleration time of the early transmitral flow velocity was longer in groups L (187 +/- 18 ms) and I (185 +/- 16 ms) compared with group S (168 +/- 17 ms, p < 0.001 for L and I vs. S), whereas A was higher in group L compared with S (43 +/- 10 vs. 51 +/- 10 cm/s, p < 0.005). Multiple regression analysis identified duration of heavy drinking as the most important variable affecting DT and A. CONCLUSIONS: Left ventricular dilation with preserved EF and impaired LV relaxation characterized LV function in chronic asymptomatic alcoholic patients. It appeared that the progression of abnormalities in LV diastolic filling related to the duration of alcoholism.

Differential susceptibility of primary cultured human skin cells to hypericin PDT in an in vitro model.

Skin cancer is the most common cancer worldwide, and its incidence rate in South Africa is increasing. Photodynamic therapy (PDT) has been shown to be an effective treatment modality, through topical administration, for treatment of non-melanoma skin cancers. Our group investigates hypericin-induced PDT (HYP-PDT) for the treatment of both non-melanoma and melanoma skin cancers. However, a prerequisite for effective cancer treatments is efficient and selective targeting of the tumoral cells with minimal collateral damage to the surrounding normal cells, as it is well established that cancer therapies have bystander effects on normal cells in the body, often causing undesirable side effects. The aim of this study was to investigate the cellular and molecular effects of HYP-PDT on normal primary human keratinocytes (Kc), melanocytes (Mc) and fibroblasts (Fb) in an in vitro tissue culture model which represented both the epidermal and dermal cellular compartments of human skin. Cell viability analysis revealed a differential cytotoxic response to a range of HYP-PDT doses in all the human skin cell types, showing that Fb (LD50=1.75µM) were the most susceptible to HYP-PDT, followed by Mc (LD50=3.5µM) and Kc (LD50>4µM HYP-PDT) These results correlated with the morphological analysis which displayed distinct morphological changes in Fb and Mc, 24h post treatment with non-lethal (1µM) and lethal (3µM) doses of HYP-PDT, but the highest HYP-PDT doses had no effect on Kc morphology. Fluorescent microscopy displayed cytoplasmic localization of HYP in all the 3 skin cell types and additionally, HYP was excluded from the nuclei in all the cell types. Intracellular ROS levels measured in Fb at 3µM HYP-PDT, displayed a significant 3.8 fold (p<0.05) increase in ROS, but no significant difference in ROS levels occurred in Mc or Kc. Furthermore, 64% (p<0.005) early apoptotic Fb and 20% (p<0.05) early apoptotic Mc were evident; using fluorescence activated cell sorting (FACS), 24h post 3µM HYP-PDT. These results depict a differential response to HYP-PDT by different human skin cells thus highlighting the efficacy and indeed, the potential bystander effect of if administered in vivo. This study contributes toward our knowledge of the cellular response of the epidermis to photodynamic therapies and will possibly enhance the efficacy of future photobiological treatments.

Low incidence of cardiac abnormalities in treated trichinosis: a prospective study of 62 patients from a single-source outbreak.

PURPOSE: The reported incidence of cardiac involvement in trichinosis is highly variable, ranging from 21% to 75%. This study sought to determine the incidence and type of cardiac lesions in trichinosis using serial echocardiographic examinations. SUBJECTS AND METHODS: Sixty-two consecutive patients admitted to the Banja Luka Medical Center during an outbreak of trichinosis (November to December 1996) were included in the study. Diagnosis was made by typical clinical presentation, positive epidemiologic history, serologic testing, and the detection of Trichinella larvae in contaminated meat. All patients underwent serial electrocardiograms and two-dimensional and Doppler echocardiographic examinations within 20 days after the onset of symptoms. Repeated echocardiographic examinations were performed weekly during the hospital stay in all patients with electrocardiographic abnormalities or an abnormal initial echocardiogram. RESULTS: Cardiac involvement (electrocardiographic and/or echocardiographic changes) was detected in 8 (13%) of the 62 patients. Nonspecific transient electrocardiographic ST-T changes were found in 6 patients (10%); 1 patient had frequent premature ventricular complexes. Echocardiographic examinations revealed pericardial effusions in 6 patients (10%), 5 of whom had minimal effusions without impairment of global and regional left ventricular systolic function. One patient had hypokinesis of the interventricular septum with a small pericardial effusion, both of which resolved within 2 weeks. Only 2 of the patients with electrocardiographic abnormalities lacked echocardiographic evidence of cardiac involvement. At 6-month follow-up, none of the patients had electrocardiographic or echocardiographic abnormalities. CONCLUSIONS: The incidence of cardiac involvement in trichinosis appears to be lower than previously reported. Pericardial effusion is the most common manifestation of cardiac involvement, and nonspecific transient electrocardiographic changes, traditionally ascribed to myocarditis, more frequently reflect pericarditis.

Acute and long-term effects of thrombolysis after anterior wall acute myocardial infarction with serial assessment of infarct expansion and late ventricular remodeling.

This study investigates the impact of thrombolysis on infarct expansion and subsequent left ventricular (LV) remodeling in patients with anterior wall acute myocardial infarction (AMI). We evaluated 51 consecutive patients (24 treated with thrombolysis) with anterior wall AMI by 2-dimensional echocardiography in the following sequence: days 1, 2, 3, and 7, after 3 and 6 weeks, and after 3, 6, and 12 months. LV end-diastolic and end-systolic volume indexes were determined from apical 2- and 4-chamber views using Simpson's biplane formula. Infarct and total LV perimeters were determined in the same views and their ratio expressed as infarct percentage. Infarct expansion was defined as: (1) an increase in infarct percentage and total perimeter >5% on days 2 to 3 in either of the views, or (2) initial infarct percentage >50% with an increase in total perimeter >5% on days 2 to 3. Coronary angiography was performed in 43 patients before discharge, and patency of the infarct-related artery was assessed using Thrombolysis in Myocardial Infarction trial criteria. Infarct expansion was detected in 23 patients. Infarct perimeter steadily decreased in patients with versus without thrombolysis and in patients with patent versus occluded infarct-related arteries. Furthermore, by logistic regression, thrombolysis (p = 0.007) and potency of the infarct-related artery (p = 0.02) were strong negative predictors of expansion, whereas initial infarct perimeter (p = 0.009) was directly associated with subsequent expansion. End-systolic volume index was higher in patients with expansion from day 1 (p = 0.003) through the end of the study (p = 0.021), and end-diastolic volume index was higher in these patients from day 2 (p = 0.012) through 12 months (p = 0.015). Thus thrombolysis, initial infarct size, and infarct-related artery patency are major predictors of infarct expansion after anterior wall AMI.

Early predictors of mitral regurgitation after acute myocardial infarction.

We analyzed early predictors of mitral regurgitation after myocardial infarction in 131 consecutive patients with first acute myocardial infarction. Our data revealed that elderly patients with larger infarcts, multivessel coronary disease, and papillary muscle region asynergy are more likely to develop mitral regurgitation in the first year after infarction.

Acute hemodynamic effects of metoprolol +/- nitroglycerin in patients with biopsy-proven lymphocytic myocarditis.

We evaluated acute hemodynamic effects of metoprolol +/- nitroglycerin in 11 patients with left ventricular dysfunction and biopsy-proven lymphocytic myocarditis. Acute administration of metoprolol improved ejection phase indexes, probably through the prolongation of diastole; the addition of a vasodilator further enhanced these effects by improving arterial elastance.

Acute effects of DDD pacing in patients with pulmonary infundibular stenosis.

We evaluated acute effects of DDD pacing (right atrium sensed and left ventricle paced) in 3 patients with pulmonary infundibular stenosis and found a decrease in dynamic right ventricular outflow gradient in all of them. It appears that acute temporary DDD pacing may decrease the dynamic obstruction of the right ventricular outflow tract in these patients, probably because of asynchronous contraction of the right ventricle induced by pacing from the left ventricular apex, with contraction of infundibular portion being delayed.

Serial assessment of left ventricular chamber stiffness after acute myocardial infarction.

Left ventricular (LV) systolic function after acute myocardial infarction (AMI) has been the subject of detailed studies during the last decade, but diastolic phenomena during and after AMI are less well understood. Recently, it has been shown that early filling deceleration time accurately predicted LV chamber stiffness in an experimental model. To assess changes of LV stiffness after AMI, we studied 116 consecutive patients with 2-dimensional and Doppler echocardiographic examinations 1, 2, 3, 7, 21, and 42 days after AMI. Coronary angiography was performed in 101 patients. For the entire study group, deceleration time decreased nonsignificantly on day 2 and subsequently increased on days 3 (p = 0.001) and 7 (p = 0.036), returning toward initial values afterward. Deceleration time was shorter in large (peak creatine kinase level >1,000 U/L) versus small infarcts (p = 0.0008) and in patients with anterior versus inferior AMI (p = 0.02); there was no difference between patients with good and poor (< or = 45%) ejection fraction. These data indicate that increased LV stiffness can be detected 24 to 48 hours after AMI, but returns to normal within several days. Chamber stiffness is higher in large and anterior infarcts, but appears to be independent of LV systolic function.

Time-related trends in the preoperative evaluation of patients with valvular stenosis.

To investigate time-related trends in the use of preoperative invasive hemodynamics in patients with pure valvular stenosis, the preoperative evaluations and preoperative echocardiograms of consecutive patients who underwent aortic or mitral valve surgery from 1986 to 1994 at the Cleveland Clinic Foundation were reviewed. The study group consisted of 1,985 patients, 1,476 with aortic stenosis and 509 with mitral stenosis. Preoperative cardiac catheterization was performed in 1,456 patients with aortic stenosis (99%) and 488 with mitral stenosis (96%). Measurement of invasive hemodynamics (including transvalvular gradients and estimated valve areas) during catheterization decreased over time both in patients with aortic (from 64% in 1986 to 30% in 1994, test for trend p <0.0001) and mitral stenosis (from 63% in 1986 to 18% in 1994, test for trend p <0.0001). After adjusting for age, gender, and other characteristics, the only predictors of performance of invasive hemodynamics in patients with aortic stenosis were more recent surgery (inverse relation, p = 0.0001) and New York Heart Association class (p = 0.01); in patients with mitral stenosis the only predictor was also more recent surgery (inverse relation, p = 0.0001). Thus, use of preoperative invasive hemodynamics in patients with valvular stenosis has markedly decreased over the last decade. This is an example of how a noninvasive modality can supercede an invasive one, even when surrounding a procedure as fundamentally invasive as valvular heart surgery.

Partial left ventriculectomy for idiopathic dilated cardiomyopathy: early results and six-month follow-up.

BACKGROUND: Recent reports show that partial left ventriculectomy improves hemodynamic and functional status in patients with dilated cardiomyopathy. This study sought to determine the effects of partial left ventriculectomy on clinical outcome and left ventricular function during 6-month follow-up. METHODS: Twenty-two patients underwent partial left ventriculectomy. Mitral valve repair was performed whenever possible, otherwise the valve was replaced. Hemodynamic and functional data were obtained at baseline, as well as 2 weeks and 6 months postoperatively. RESULTS: Overall, 7 of 22 patients died; there were three early and four late deaths. One-year survival was 68%+/-10%. Ejection fraction increased from 23.9%+/-6.8% before the operation to 40.7%+/-12.5% at 2 weeks and to 36.8%+/-7.7% at 6 months (p<0.001, for both). The cardiac index before the operation, at 2 weeks, and at 6 months was 2.3+/-0.8, 2.9+/-0.6, and 3.4+/-1.0 L/m2 per minute, respectively (p = 0.035, and p = 0.009, compared with baseline). The increase in ejection fraction 2 weeks postoperatively was less in patients with left circumflex artery dominance (10.9%+/-3.2% compared with 19.9%+/-10.7%, respectively, p = 0.017). At 6-month follow up, all surviving patients except one improved New York Heart Association functional class when compared with preoperative status (from 3.8+/-0.4 to 1.4+/-0.6, p = 0.0002). CONCLUSIONS: Early hemodynamic improvement after partial left ventriculectomy was maintained during midterm follow-up.

Partial left ventriculectomy improves left ventricular end systolic elastance in patients with idiopathic dilated cardiomyopathy.

OBJECTIVE: To assess the effect of partial left ventriculectomy (PLV) on estimate of left ventricular end systolic elastance (Ees), arterial elastance, and ventriculoarterial coupling. PATIENTS: 11 patients with idiopathic dilated cardiomyopathy before and two weeks after PLV, and 11 controls. INTERVENTIONS: Single plane left ventricular angiography with simultaneous measurements of femoral artery pressure was performed during right heart pacing before and after load reduction. RESULTS: PLV increased mean (SD) Ees from 0.52 (0.27) to 1.47 (0.62) mm Hg/ml (p = 0.0004). The increase in Ees remained significant after correction for the change in left ventricular mass (p = 0.004) and end diastolic volume (p = 0.048). As PLV had no effect on arterial elastance, ventriculoarterial coupling improved from 3.25 (2.17) to 1.01 (0.93) (p = 0.017), thereby maximising left ventricular stroke work. CONCLUSION: It appears that PLV improves both Ees and ventriculoarterial coupling, thus increasing left ventricular work efficiency.

Association of ventricular arrhythmias with left ventricular remodelling after myocardial infarction.

OBJECTIVE: To assess the relation between ventricular arrhythmias after myocardial infarction and left ventricular remodelling. DESIGN: Prospective study with consecutive patients. METHODS: 97 patients with acute myocardial infarction underwent serial echocardiographic examinations (days 1, 2, 3, and 7, and after 3 weeks) to determine end diastolic volume, end systolic volume, and ejection fraction; volumes were normalised for body surface area and expressed as indices. Holter monitoring was performed on the day of the final echocardiogram. Coronary angiography was performed in 88 patients before hospital discharge. RESULTS: Complex ventricular arrhythmias (defined as Lown class 3-5) were found in 16 of 97 patients. In logistic regression models, variables predictive of complex ventricular arrhythmias were end systolic volume index on admission (b = 0.054, P = 0.015) and end diastolic volume index after three weeks (b = 0.034, P = 0.012). Complex arrhythmias were also related to the increase of end diastolic and end systolic volume indices throughout the study (F = 5.62, P = 0.046, and F = 6.42, P = 0.017, respectively by MANOVA). A two stage linear regression model of ventricular volume versus time from infarct showed that both intercept (initial volume) and slope (rate of increase) were higher for patients with complex arrhythmias in both diastole and systole (P < 0.001 for all). CONCLUSIONS: Complex ventricular arrhythmias after myocardial infarction are related to the increase of left ventricular volume rather than to depressed ejection fraction. Complex arrhythmias may be an aetiological factor linking left ventricular remodelling with higher mortality, but larger follow up studies of patients with progressive left ventricular dilatation after myocardial infarction are necessary to answer these questions.

Knudsen cell mass spectrometric investigation of the PbO-ZrO(2)-TiO(2) system.

Knudsen effusion mass spectrometry (KEMS) was used for direct determination of lead oxide activity as a function of temperature in various regions of the PbO-ZrO(2)-TiO(2) system. From the results, the enthalpy, Gibbs free energy and entropy of formation of PbTiO(3) (PT), PbZrO(3) (PZ) and Pb(Zr,Ti)O(3) (PZT) were evaluated. In addition, the single phase widths of Pb(Zr(0.5)Ti(0.5))O(3) and PbTiO(3) perovskite structures were determined at 1100 K. The reaction rate of PZT synthesis in vacuo was followed by direct measurement of the change of PbO activity with time. Lead oxide activity in stoichiometric Pb(Zr(0.5)Ti(0.5))O(3), PbTiO(3) and Pb(0.968)(Zr(0.5)Ti(0.5))O(2.968) (3% lead deficient) at 850 degrees C was found to be 0.40, 0.45 and 0.1, respectively. PZT, PT and PZ powder samples prepared by a solid state procedure were also measured, all revealing lead deficiency. Copyright 1999 John Wiley & Sons, Ltd.