Diagnostic accuracy of prenatal ultrasound in coarctation of aorta: systematic review and individual participant data meta-analysis.

OBJECTIVE: To determine the diagnostic accuracy of prenatal ultrasound in detecting coarctation of the aorta (CoA). METHODS: An individual participant data meta-analysis was performed to report on the strength of association and diagnostic accuracy of different ultrasound signs in detecting CoA prenatally. MEDLINE, EMBASE and CINAHL were searched for studies published between January 2000 and November 2021. Inclusion criteria were fetuses with suspected isolated CoA, defined as ventricular and/or great vessel disproportion with right dominance on ultrasound assessment. Individual participant-level data were obtained by two leading teams. PRISMA-IPD and PRISMA-DTA guidelines were used for extracting data, and the QUADAS-2 tool was used for assessing quality and applicability. The reference standard was CoA, defined as narrowing of the aortic arch, diagnosed after birth. The most commonly evaluated parameters on ultrasound, both in B-mode and on Doppler, constituted the index test. Summary estimates of sensitivity, specificity, diagnostic odds ratio (DOR) and likelihood ratios were computed using the hierarchical summary receiver-operating-characteristics model. RESULTS: The initial search yielded 72 studies, of which 25 met the inclusion criteria. Seventeen studies (640 fetuses) were included. On random-effects logistic regression analysis, tricuspid valve/mitral valve diameter ratio > 1.4 and > 1.6, aortic isthmus/arterial duct diameter ratio < 0.7, hypoplastic aortic arch (all P < 0.001), aortic isthmus diameter Z-score of < -2 in the sagittal (P = 0.003) and three-vessel-and-trachea (P < 0.001) views, pulmonary artery/ascending aorta diameter ratio > 1.4 (P = 0.048) and bidirectional flow at the foramen ovale (P = 0.012) were independently associated with CoA. Redundant foramen ovale was inversely associated with CoA (P = 0.037). Regarding diagnostic accuracy, tricuspid valve/mitral valve diameter ratio > 1.4 had a sensitivity of 72.6% (95% CI, 48.2-88.3%), specificity of 65.4% (95% CI, 46.9-80.2%) and DOR of 5.02 (95% CI, 1.82-13.9). The sensitivity and specificity values were, respectively, 75.0% (95% CI, 61.1-86.0%) and 39.7% (95% CI, 27.0-53.4%) for pulmonary artery/ascending aorta diameter ratio > 1.4, 47.8% (95% CI, 14.6-83.0%) and 87.6% (95% CI, 27.3-99.3%) for aortic isthmus diameter Z-score of < -2 in the sagittal view and 74.1% (95% CI, 58.0-85.6%) and 62.0% (95% CI, 41.6-78.9%) for aortic isthmus diameter Z-score of < -2 in the three-vessel-and-trachea view. Hypoplastic aortic arch had a sensitivity of 70.0% (95% CI, 42.0-88.6%), specificity of 91.3% (95% CI, 78.6-96.8%) and DOR of 24.9 (95% CI, 6.18-100). The diagnostic yield of prenatal ultrasound in detecting CoA did not change significantly when considering multiple categorical parameters. Five of the 11 evaluated continuous parameters were independently associated with CoA (all P < 0.001) but all had low-to-moderate diagnostic yield. CONCLUSIONS: Several prenatal ultrasound parameters are associated with an increased risk for postnatal CoA. However, diagnostic accuracy is only moderate, even when combinations of parameters are considered. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Advancement flap to cover a defect between the junction of the alar base and the upper lip.

Reconstruction following excision of skin lesions at the cosmetically sensitive junction between the alar base and upper lip continues to be challenging for surgeons. We describe an advancement flap from the nasolabial fold area to reconstruct such defects. Our case demonstrates a gentleman with a clinically diagnosed BCC between the alar base and upper lip. An advancement flap from the nasolabial area was designed to reconstruct the defect, with two Burrow's triangles excised to prevent standing cones. The scar of the two Burrow's triangles falls over the nasolabial fold, resulting in the integration of the scar within the natural line. This flap design also maintains of the level of the upper lip, the shape and position of the nostril, and minimises flattening of the philtrum. Excellent cosmetic results were seen six weeks post-op.

[Out-of-hospital ventilation after prolonged weaning]. / Außerklinische Beatmung nach prolongiertem Weaning.

An increasing number of patients require prolonged weaning from mechanical ventilation as a result of advanced age, patient comorbidities, technical progress in surgery and intensive care medicine. The data of the WeanNet register show that more than half (64%) of patients transferred from the intensive care unit (ICU) to a specialized weaning center could definitely be weaned from the respirator. Weaning failure was associated with prolonged ventilation prior to transfer to a weaning center, low body mass index, pre-existing neuromuscular diseases and advanced age. The number of patients with out of hospital ventilation who had to be re-hospitalized because of ventilation control or as part of emergency management quadrupled in Germany between 2006 and 2016. Invasive out-of-hospital ventilation and long-term noninvasive ventilation are associated with a significant loss of autonomy and with low quality of life. Therefore, the initiation must be carefully reviewed and regularly re-evaluated in the context of patient comorbidities and, if necessary, decisions should be made with respect to changing treatment targets. Specialized weaning centers have been established for patients in whom weaning on the ICU was unsuccessful. In cases of persisting weaning failure the adequate transition to out-of-hospital ventilation should be managed by a weaning unit. Weaning centers are responsible for outpatient invasive or noninvasive ventilation strategies and control of treatment quality. Depending on the infrastructure and networking of the respective weaning center, it is basically also possible to provide outpatient care for clinically stable patients in a cooperation model together with pulmonologists in private practice experienced in respiratory medicine.

Nasal high flow, but not supplemental O2, reduces peripheral vascular sympathetic activity during sleep in COPD patients.

INTRODUCTION: Patients with COPD have increased respiratory loads and altered blood gases, both of which affect vascular function and sympathetic activity. Sleep, particularly rapid eye movement (REM) sleep, is known to exacerbate hypoxia and respiratory loads. Therefore, we hypothesize that nasal high flow (NHF), which lowers ventilatory loads, reduces sympathetic activity during sleep and that this effect depends on COPD severity. METHODS: We performed full polysomnography in COPD patients (n=17; FEV1, 1.6±0.6 L) and in matched controls (n=8). Participants received room air (RA) at baseline and single night treatment with O2 (2 L/min) and NHF (20 L/min) in a random order. Finger pulse wave amplitude (PWA), a measure of vascular sympathetic tone, was assessed by photoplethysmography. Autonomic activation (AA) events were defined as PWA attenuation ≥30% and indexed per hour for sleep stages (AA index [AAI]) at RA, NHF, and O2). RESULTS: In COPD, sleep apnea improved following O2 (REM-apnea hypopnea index [AHI] with RA, O2, and NHF: 18.6±20.9, 12.7±18.1, and 14.4±19.8, respectively; P=0.04 for O2 and P=0.06 for NHF). REM-AAI was reduced only following NHF in COPD patients (AAI-RA, 21.5±18.4 n/h and AAI-NHF, 9.9±6.8 n/h, P=0.02) without changes following O2 (NHF-O2 difference, P=0.01). REM-AAI reduction was associated with lung function expressed as FEV1 and FVC (FEV1: r=-0.59, P=0.001; FEV1/FVC: r=-0.52 and P=0.007). CONCLUSION: NHF but not elevated oxygenation reduces peripheral vascular sympathetic activity in COPD patients during REM sleep. Sympathetic off-loading by NHF, possibly related to improved breathing mechanics, showed a strong association with COPD severity.

Improving the Stability of Amino-Containing Plasma Polymer Films in Aqueous Environments.

Plasma polymer films that contain amine groups (NH2-PPFs) are known to degrade over time, particularly in aqueous environments. To reduce such aging effects, a vertical chemical gradient regarding the amine group density was explored ranging over a few nanometers at the coating surface. The gradient-containing nanofilms were formed in low-pressure plasma by tuning plasma conditions while keeping the plasma "switched on". The coating process started with a more cross-linked NH2-PPF (70 W, 4:7 NH3/C2H4), followed by the deposition of a few nanometers of a less cross-linked yet more functional NH2-PPF (50 W, 7:7 NH3/C2H4). Characterization of the prepared gradient coatings showed that the chemical composition depends on the NH3/C2H4 gas flow ratio, as observed by different analytical methods: plasma diagnostics during deposition and depth profiling analyses of the deposited coating. Finally, surface chemistry was analyzed during air and water aging, showing a similar aging process of the NH2-PPF single layer and NH2-PPF with a vertical chemical gradient in air, while the stability of the gradient coating was found to be enhanced under aqueous conditions maintaining an [NH2]/[C] amount of ∼1%.

Application of co-anaerobic digester's effluent for sustainable agriculture and aquaculture in the Mekong Delta, Vietnam.

This investigation studied the application of digester effluent from co-digestion of pig manure and spent mushroom substrate as a fertilizer for leaf mustard planting and as feed for Tilapia fish growing. The fish raising experiment was set up in 1 × 1 × 1 m hapa conditions (triplicate for each treatment) with the density of 10 individiual per hapa; the fish weight and length were measured every 10 days for 50 continuous days. The leaf mustard was planted in real conditions at farmer's garden with normal cultivation style, and the weight and length of the plant were measured four times during the growing period. The study result shows that the harvest yield of leaf mustard fertilized by the digester effluent was 5.4 times higher than that by an inorganic fertilizer (IF). In addition to its contribution to a higher yield, the digester effluent accelerated the flower formation and shortened cultivation duration. For Tilapia fish culture, the growing rate of fish in the treatments supplied with 50% digester effluent + 50% commercial food (CF) was not significantly different in comparison to the fish cultivation with 100% CF. The result strongly confirms that the digester effluent from a co-digestion biogas plant of pig dung and spent mushroom compost is possible to be used as an organic fertilizer well for not only vegetable planting but also fish culture.

Validation of the Flemish version of the Quality of Life in Short Stature Youth (QoLISSY) questionnaire.

OBJECTIVES: The Quality of Life in Short Stature Youth (QoLISSY) questionnaire was recently developed in five European countries to assess health-related quality of life in children and adolescents with idiopathic short stature or growth hormone deficiency from child and parent perspectives. In addition to the existing French version, a Flemish version is needed for use of QoLISSY in the Flemish speaking part of Belgium. METHODS: Children (8-18 years) and their parents recruited from two Belgian paediatric endocrinology clinics completed the QoLISSY in a cross-sectional study. Cronbach's Alpha and test-retest reliability was assessed. Validity was examined by correlation with the generic KIDSCREEN questionnaire as well as by group comparisons according to diagnostic and treatment status. RESULTS: The QoLISSY scales had an acceptable internal consistency with Cronbach's Alpha ranging from 0·80 to 0·94 (child version) and from 0·77 to 0·92 (parent version). Test-retest reliability correlation coefficients ranged from r = 0·75 to 0·89 in the child version and from r = 0·58 to 0·85 in the parent version. Moderate correlations with the generic KIDSCREEN questionnaire suggested construct validity. Differences between child groups according to child age, underlying diagnosis, and degree of height deficit were found. Correlations with the European QoLISSY were significant for all scales. DISCUSSION: The Flemish QoLISSY instrument is a psychometrically sound, reliable, and valid short stature specific questionnaire measuring health-related quality of life. It is expected to be of great use in upcoming clinical research on growth disorders and growth hormone treatment in Belgium and Europe.

Time course of the induction of homeostatic plasticity generated by repeated transcranial direct current stimulation of the human motor cortex.

Several mechanisms have been proposed that control the amount of plasticity in neuronal circuits and guarantee dynamic stability of neuronal networks. Homeostatic plasticity suggests that the ease with which a synaptic connection is facilitated/suppressed depends on the previous amount of network activity. We describe how such homeostatic-like interactions depend on the time interval between two conditioning protocols and on the duration of the preconditioning protocol. We used transcranial direct current stimulation (tDCS) to produce short-lasting plasticity in the motor cortex of healthy humans. In the main experiment, we compared the aftereffect of a single 5-min session of anodal or cathodal tDCS with the effect of a 5-min tDCS session preceded by an identical 5-min conditioning session administered 30, 3, or 0 min beforehand. Five-minute anodal tDCS increases excitability for about 5 min. The same duration of cathodal tDCS reduces excitability. Increasing the duration of tDCS to 10 min prolongs the duration of the effects. If two 5-min periods of tDCS are applied with a 30-min break between them, the effect of the second period of tDCS is identical to that of 5-min stimulation alone. If the break is only 3 min, then the second session has the opposite effect to 5-min tDCS given alone. Control experiments show that these shifts in the direction of plasticity evolve during the 10 min after the first tDCS session and depend on the duration of the first tDCS but not on intracortical inhibition and facilitation. The results are compatible with a time-dependent "homeostatic-like" rule governing the response of the human motor cortex to plasticity probing protocols.

Pilot project of mechanical-biological treatment of waste in Brazil.

By mechanical-biological treatment (MBT) of residual municipal solid waste the behaviour of landfills can be significantly improved. After MBT the organic content (COD and BOD5), total organic carbon, and total nitrogen in the leachate, as well as the gas production rate, are reduced to values lower than 90% of the fresh untreated waste. The volume of the stabilized material to be disposed on landfills decreases enormously, by up to 70%. The monitoring effort for a landfill constructed under these conditions is reduced to a minimum and the stabilized material can be used in other ways, as material for reforestation, for cover material or for thermal utilization to produce energy. Environmental conditions are important in MBT, as well as waste characteristics. This paper describes the results of a pilot project of MBT performed in Rio de Janeiro, Brazil. The results have shown that this technology can be used successfully in developing countries, with economy for the society and important results for the environment.

Pharmacological modulation of cortical excitability shifts induced by transcranial direct current stimulation in humans.

Transcranial direct current stimulation (tDCS) of the human motor cortex results in polarity-specific shifts of cortical excitability during and after stimulation. Anodal tDCS enhances and cathodal stimulation reduces excitability. Animal experiments have demonstrated that the effect of anodal tDCS is caused by neuronal depolarisation, while cathodal tDCS hyperpolarises cortical neurones. However, not much is known about the ion channels and receptors involved in these effects. Thus, the impact of the sodium channel blocker carbamazepine, the calcium channel blocker flunarizine and the NMDA receptor antagonist dextromethorphane on tDCS-elicited motor cortical excitability changes of healthy human subjects were tested. tDCS-protocols inducing excitability alterations (1) only during tDCS and (2) eliciting long-lasting after-effects were applied after drug administration. Carbamazepine selectively eliminated the excitability enhancement induced by anodal stimulation during and after tDCS. Flunarizine resulted in similar changes. Antagonising NMDA receptors did not alter current-generated excitability changes during a short stimulation, which elicits no after-effects, but prevented the induction of long-lasting after-effects independent of their direction. These results suggest that, like in other animals, cortical excitability shifts induced during tDCS in humans also depend on membrane polarisation, thus modulating the conductance of sodium and calcium channels. Moreover, they suggest that the after-effects may be NMDA receptor dependent. Since NMDA receptors are involved in neuroplastic changes, the results suggest a possible application of tDCS in the modulation or induction of these processes in a clinical setting. The selective elimination of tDCS-driven excitability enhancements by carbamazepine proposes a role for this drug in focussing the effects of cathodal tDCS, which may have important future clinical applications.

[Microbial emissions in collection of residential garbage]. / Mikrobielle Immissionen bei der Einsammlung von Siedlungsabfällen.

Two exemplary investigations with different questions were carried out in Munich and Stuttgart by sampling bio-aerosols due to and during the collection and emptying of different types of waste bins. The emissions were regarded qualitatively and quantitatively, in order to answer the question, whether and to which amount differences of bio-aerosol emissions occurred due to the kind of wastes collected. The lowest emissions of airborne microorganisms were found during the collection of the paper waste fraction. In comparison, the amounts of them during the collection of unseparated household wastes as well as source separated bio-wastes and the remaining residual waste fraction were higher. Between the three latter, no significant differences could be found, only a tendency of higher values for the thermotolerant mould A. fumigatus during the collection of bio- and residual wastes was observed. Maybe this was caused by special features of the different sampling locations, but it could also be due to the longer collection intervals (bio- and residual wastes were partially collected every two weeks, unseparated wastes every week).

Polyamine modulation of mitochondrial calcium transport. II. Inhibition of mitochondrial permeability transition by aliphatic polyamines but not by aminoglucosides.

In this study, the effects of polyamines and analogous compounds on mitochondrial permeability transition were characterized to distinguish between these effects and those on mitochondrial Ca2+ uptake, which are described in an accompanying report (Rustenbeck et al., Biochem Pharmacol 8: 977-985, 1998). When a transitional Ca2+ release from Ca2+-loaded mitochondria was induced by an acute increase in Ca2+ concentration in a cytosol-adapted incubation medium (Ca2+ pulse), this process was inhibited, but not abolished by spermine in the concentration range of 0.4 to 20 mM. The aminoglucoside, gentamicin, and the basic polypeptide, poly-L-lysine, which like spermine are able to enhance mitochondrial Ca2+ accumulation (preceding paper), had no or only a minimal inhibitory effect, while the aliphatic polyamine, bis(hexamethylene)triamine, which is unable to enhance mitochondrial Ca2+ accumulation, achieved a complete inhibition at 4 mM. The conclusion that the Ca2+ efflux was due to opening of the permeability transition pore was supported by measurements of mitochondrial membrane potential, ATP production, and oxygen consumption. Mg2+, a known inhibitor of mitochondrial membrane permeability transition, did not mimic the effects of spermine on mitochondrial Ca2+ accumulation, while ADP, the main endogenous inhibitor, showed both effects. However, a combination of spermine and ADP was significantly more effective than ADP alone in restoring low Ca2+ concentrations after a Ca2+ pulse. Two different groups of spermine binding sites were found at intact liver mitochondria, characterized by dissociation constants of 0.5 or 4.7 mM and maximal binding capacities of 4.6 or 19.7 nmol/mg of protein, respectively. In contrast to aminoglucosides, the aliphatic polyamine bis(hexamethylene)triamine did not displace spermine from mitochondrial binding sites. The total intracellular concentration of spermine in hepatocytes was measured to be ca. 450 microM and the free cytoplasmic concentration was estimated to be in the range of 10-100 microM. In conclusion, the enhancement of mitochondrial Ca2+ uptake by spermine is not an epiphenomenon of the inhibition of permeability transition. The physiological role of spermine appears to be that of an enhancer of mitochondrial Ca2+ accumulation rather than an inhibitor of permeability transition.

Mood and the correction of positive versus negative stereotypes.

The present research examined the effects of sadness on the correction of social stereotypes. Participants who either were not induced to feel sad were asked to form an impression of a single individual who belonged to a group that had either stereotypically positive or negative implications. Experiments 1 and 2 showed that sad people corrected for their negative, but not for their positive stereotypes. Experiment 3 demonstrated that this asymmetry was not due to stereotype valence per se but to whether the stereotype was perceived as an inappropriate basis for judgment. A model is presented that suggests that sad people do not simply ignore category-based information, but rather correct for their stereotypes only when they are perceived as inappropriate, which tends to be more often the case if the stereotype is negative than if it is positive. The implications of the present results for 4 extant models of mood and information processing are discussed.

[Histologic classification and morphologic prognostic factors in malignant ovarian tumors]. / Histologische Klassifikation und morphologische Prognosefaktoren bei malignen Ovarialtumoren.

Most cases of death in genital neoplasms of females are caused by ovarian cancer. Prognostic factors are the postoperative tumor, tumor stage (FIGO, pTNM), age, tumors among family, and the reproductive history. On the basis of 710 malignant ovarian tumors we describe the histogenetic classification and compare the morphologic diagnosis with additional prognostic factors by literature to give a practical review of ovarian neoplasms. The morphologic prognostic factors are the histological subtype, tumor grading and perhaps the receptor status. Worse prognosis, despite of tumor grading, show undifferentiated carcinomas, followed by the serous and mucinous subtype. Endometrioid carcinomas have the best prognosis. Malignant Mullerian tumors show a very aggressive behavior. After the introduction of polychemotherapy the sex-cord- and germ cell-tumors show better prognoses. New prognostic factors are DNA-parameters (ploidy, S-phase-fraction), detection of oncogenes and tumor suppressor genes, cellular adhesion molecules (integrins, CD 44-splicing variants), and the proliferation rate of the tumor. Perhaps, these factors show prognostic relevance for individual treatment. A correct histologic classification with consideration of all morphology related prognostic factors and the knowledge about them is necessary for oncologists to choose the optimal individual therapeutic treatment.

Flicker spectroscopy of erythrocytes. A sensitive method to study subtle changes of membrane bending stiffness.

Frequency analysis of thermally excited surface undulations of erythrocytes leading to the flicker phenomenon is applied to determine biochemically and physically induced modulations of the membrane curvature elasticity. Flicker spectra of individual cells fixed to the window of a flow chamber by polylysine are taken by phase contrast microscopy, enabling investigations of the reversibility of the structural modifications. The spectra may be approximated by Lorentzian lines in most cases. By measuring the amplitude (at zero frequency) and the line width, effects of the structural changes on the curvature elastic constant, Kc, and the wavelength distribution of the undulations may be studied separately. Effect of physically induced modifications: The temperature dependence of the flicker spectra are taken from 10 degrees C to 37 degrees C. Above 20 degrees C, Kc decreases with increasing temperature whereas the reverse holds below this limit. The latter anomalous behaviour is explained in terms of a conformational change associated with protein and lipid lateral phase separation. The bending stiffness increases when the cells swell osmotically, owing to surface tension effects. The dependence of the flicker spectra on the viscosity of the suspension medium agrees with the theoretical prediction. Biochemically and drug induced modifications: 5 vol% of ethanol leads to a pronounced and reversible suppression of the long wavelength undulations without altering the discoid cell shape and without affecting the bending stiffness appreciably. Adsorption of dextran to the glycocalix increases Kc by a factor of 1.6 at saturation. The bending stiffness is increased by a factor of 1.3 after cross-linking the proteins with the SH-oxidizing agent diamid. Injection of Ca++ into the cell via ionophores evokes (within 10 min) the formation of fine--probably spectrin free--spicules. This leads to an increase in Kc by a factor of 1.3 which is explained in terms of a lateral condensation of the spectrin/actin network. The spicule formation and Kc change is completely reversible (within 2 min) after perfusion with Ca++-free buffer. Cholesterol depletion leads first to a continuous increase in Kc without change of the cell shape whereas a sudden discocyte- to echinocyte transformation sets in below a critical steroid content. The latter transition is also observed in cell suspensions and is reminiscent of a phase transition. The anti-tumor drug actinomycin D evokes an increase in the bending stiffness Kc by a factor of two, suggesting that its effect is at least partially due to a modulation of the membrane structure.(ABSTRACT TRUNCATED AT 400 WORDS)

[Chronic pancreatitis: sensitivity, specificity and predictive value of the pancreolauryl test]. / Chronische Pankreatitis: Sensitivität, Spezifität und prädiktiver Wert des Pankreolauryltests.

Assessment of the clinical value of the pancreolauryl test (PLT) in the literature range from "useless" to a specifity of 95% and a sensitivity of 98%. In this work, our own data are presented in relation to various reference methods. The results are derived from the largest collective investigated to data, comprising 40 controls and 391 patients (108 with chronic pancreatitis and 283 with other gastrointestinal disorders). The specifity of the the PLT varies between 81% and 95% according to the "quality" of the control collective. The PLT is particularly frequently pathological in patients with diseases in the region of the gallbladder/bile duct and the gastrointestinal tract. The sensitivity of the PLT for chronic pancreatitis varies between 68% and 100%, depending on 9 different reference methods employed. Based on the prevalence of chronic pancreatitis with exocrine insufficiency in various patient collectives, the predictive value of the PLT for the presence of this disorder can be calculated using our data.

Variation of frequency spectrum of the erythrocyte flickering caused by aging, osmolarity, temperature and pathological changes.

Frequency spectra of the surface undulations (flickering) of erythrocyte plasma membranes are measured by direct spectral analysis of the intensity fluctuations of the light passing the cells in a phase contrast microscope. Spectra are taken as a function (1) of the temperature (2) of the viscosity and osmolarity of the outer medium (3) of the aging of cells and (4) of pathological transformations. The spectra are approximately superpositions of two Lorentzian lines. At large frequencies, f, the spectra follow f-2. This behaviour can be interpreted in terms of cell thickness fluctuations caused by thermally excited membrane undulations provided the range of wavelengths is small. The undulations are determined by the membrane curvature elasticity while the lateral tension is negligibly small for cells of discoid shape. The technique presented allows accurate measurements of relative curvature (bending) elastic constants. The spectra of freshly drawn cells are remarkably reproducible. Aging of the cells in the medium leads to an increase in the curvature elastic constant. A decrease in osmolarity causes a reduction in the intensity and line width of the spectra and the flickering vanishes if the cell approaches a spherical shape. The effect of temperature between 10 and 40 degrees C is astonishingly small with the exception of a sudden increase in the amplitude with increasing temperature at 35 degrees C. The flicker spectra of a large fraction of the cells from patients suffering from cronical alcoholism exhibit a reduced line width or an increase in the curvature elastic constant.

Optimization of the regular frequency of the heart in atrial fibrillation in relation to the cardiac output.

In atrial fibrillation an optimal frequency value has been derived to give the maximum cardiac output. A multiple, non-linear regression analysis of phasic aortic flow velocity in 12 patients with atrial fibrillation yields the parameters: (i) upper limiting frequency, fc; and (ii) 'optimal' frequency of the heart fo = fc/2. fo is defined at maximum cardiac output in resting conditions. An estimate of fc may be obtained from the carotid pulse tracing in a non-invasive way for the individual patient. The maximum cardiac output at fo ranges between 100% and 125% of the cardiac output was measured in the atrial fibrillatory state with irregular excitation of the ventricles. The greater the degree of irregularity of atrial fibrillation, the more expressed was the potential rise in cardiac output at the optimal regularization frequency. In chronic atrial fibrillation a regular excitation of the ventricles could be achieved by pharmacological agents, such as Verapamil or by ventricular pacing, without restitution of normal sinus rhythm. In critically ill patients with atrial fibrillation and the low cardiac output syndrome the heart rate should be adjusted to the individual cardiac output-related optimal frequency.