Pulmonary anatomy and a case of unilateral aplasia in a common snapping turtle (Chelydra serpentina): developmental perspectives on cryptodiran lungs.

The common snapping turtle (Chelydra serpentina) is a well studied and broadly distributed member of Testudines; however, very little is known concerning developmental anomalies and soft tissue pathologies of turtles and other reptiles. Here, we present an unusual case of unilateral pulmonary aplasia, asymmetrical carapacial kyphosis, and mild scoliosis in a live adult C. serpentina. The detailed three-dimensional (3D) anatomy of the respiratory system in both the pathological and normal adult C. serpentina, and a hatchling are visualized using computed tomography (CT), microCT, and 3D digital anatomical models. In the pathological turtle, the right lung consists of an extrapulmonary bronchus that terminates in a blind stump with no lung present. The left lung is hyperinflated relative to the normal adult, occupying the extra coelomic space facilitated by the unusual mid-carapacial kyphotic bulge. The bronchial tree of the left lung retains the overall bauplan of the normal specimens, with some minor downstream variation in the number of secondary airways. The primary difference between the internal pulmonary structure of the pathological individual and that of a normal adult is a marked increase in the surface area and density of the parenchymal tissue originating from the secondary airways, a 14.3% increase in the surface area to volume ratio. Despite this, the aplasia has not had an impact upon the ability of the turtle to survive; however, it did interfere with aquatic locomotion and buoyancy control under water. This turtle represents a striking example of a non-fatal congenital defect and compensatory visceral hypertrophy.

Oesophageal stenting in a district general hospital.

BACKGROUND: Oesophageal carcinoma is the ninth most common malignancy in the UK with five year survival rate of only 8%. Most patients with dysphagia present at an advanced stage. Endoscopic stent insertion is a valid method of palliation. We present the outcomes of patients stented at a district general hospital. METHOD: This is a retrospective study of patients presenting to a district general hospital with inoperable oesophageal obstruction resulting in stent insertion from December 2000 to September 2006. Case notes were reviewed for demographics, diagnosis, treatment, complication and outcome. RESULTS: Fifty-seven patients were stented endoscopically by a single surgeon during the study period for incurable oesophageal obstruction. Forty were male and 17 female (mean age 71.9 range 39-92). Most common causes were advanced adenocarcinoma (34; 60%) and squamous cell carcinoma (16; 28%). Other rarer causes were benign stricture of the oesophagus, lung carcinoma, non-Hodgkin's lymphoma and salivary gland tumour. Of the 50 patients with oesophageal carcinoma, strictures were in the lower third (in 68%), middle third (in 30%) and proximal third (in 2%). Twenty-four (42%) patients developed a complication, including overgrowth (14; 25%), migration (8; 14%), tracheo-oesophageal fistula (2; 4%) and perforation (1; 2%). There was an overall improvement in dysphagia in 41 (72%). CONCLUSION: Endoscopic stenting for advanced oesophageal obstruction is a well-tolerated procedure, which is acceptable to patients. Despite a significant complication rate, it allows the relief of dysphagia in most patients and therefore should be considered for all patients in this category.

Effects of stress on heart rate complexity--a comparison between short-term and chronic stress.

This study examined chronic and short-term stress effects on heart rate variability (HRV), comparing time, frequency and phase domain (complexity) measures in 50 healthy adults. The hassles frequency subscale of the combined hassles and uplifts scale (CHUS) was used to measure chronic stress. Short-term stressor reactivity was assessed with a speech task. HRV measures were determined via surface electrocardiogram (ECG). Because respiration rate decreased during the speech task (p<.001), this study assessed the influence of respiration rate changes on the effects of interest. A series of repeated-measures analyses of covariance (ANCOVA) with Bonferroni adjustment revealed that short-term stress decreased HR D2 (calculated via the pointwise correlation dimension PD2) (p<.001), but increased HR mean (p<.001), standard deviation of R-R (SDRR) intervals (p<.001), low (LF) (p<.001) and high frequency band power (HF) (p=.009). Respiratory sinus arrhythmia (RSA) and LF/HF ratio did not change under short-term stress. Partial correlation adjusting for respiration rate showed that HR D2 was associated with chronic stress (r=-.35, p=.019). Differential effects of chronic and short-term stress were observed on several HRV measures. HR D2 decreased under both stress conditions reflecting lowered functionality of the cardiac pacemaker. The results confirm the importance of complexity metrics in modern stress research on HRV.

Coordination dynamics of circulatory and respiratory rhythms during psychomotor drive reduction.

A 0.15-Hz rhythm band in cutaneous blood oscillations in awake human subjects was studied in cardiovascular-respiratory time series of five subjects relaxing naïvely or practicing hypnoid relaxation (autogenic training, or AT). Time series analysis used nonlinear algorithms, time-frequency distribution (TFD), postevent scan (PES) method, and linear fast Fourier transform (FFT) algorithm. This 0.15-Hz rhythm band caused phase synchronization with respiration at 1:2, 1:1, and 2:1 integer number (n/m) ratios for extended periods. During wave epochs, the 0.15-Hz rhythm band was amplified, causing the 0.15-Hz rhythm band to also appear in interbeat intervals and arterial blood pressure fluctuations. If phase synchronization of the 0.15-Hz rhythm band with respiration was established at a 1:1 integer number ratio, it was maintained and resulted in consensualization of all cardiovascular-respiratory oscillations at this frequency. Simultaneous cardiovascular and respiratory oscillations at about 0.1 Hz did not affect the appearance of the 0.15-Hz rhythm band in the photoplethysmography (PPG) signal. Recent evidence suggests the emergence of the 0.15-Hz rhythm band and n/m phase synchronization to result from nonequilibrium phase transitions operational in the network of lower brainstem neurons and associated parasympathetic neuronal effectors. These findings corroborate our notion of the 0.15-Hz rhythm band as a marker of the trophotropic mode of operation.

Nonstationary time-series analysis applied to investigation of brainstem system dynamics.

Previous investigations of the dynamic organization of the lower brainstem and its relation to peripheral and other central nervous systems were predominantly performed by linear methods. These are based on time-averaging algorithms, which merely can be applied to stationary signal intervals. Thus, the current concept of the common brainstem system (CBS) in the reticular formation (RF) of the lower brainstem and basic types of its functional organization have been developed. Here, we present experiments where neuronal activities of the RF and the nucleus tractus solitarii (NTS, first relay station of baroreceptor afferents) were recorded together with related parameters of electroencephalogram (EEG), respiration, and cardiovascular system. The RF neurons are part of the CBS, which participates in regulation and coordination of cardiovascular, respiratory, and motor systems, and vigilance. The physiological time series, thus acquired, yield information about the internal dynamic coordination of the participating regulation processes. The major problem in evaluating these data is the nonlinearity and nonstationarity of the signals. We used a set of especially designed time resolving methods to evaluate nonlinear dynamic couplings in the interaction between CBS neurons and cardiovascular signals, respiration and the EEG, and between NTS neurons (influenced by baroreceptor afferents) and CBS neurons.

Phase transitions in the common brainstem and related systems investigated by nonstationary time series analysis.

Neuronal activities of the reticular formation (RF) of the lower brainstem and the nucleus tractus solitarii (NTS, first relay station of baroreceptor afferents) were recorded together in the anesthized dog with related parameters of EEG, respiration and cardiovascular system. The RF neurons are part of the common brainstem system (CBS) which participates in regulation and coordination of cardiovascular, respiratory, somatomotor systems, and vigilance. Multiple time series of these physiological subsystems yield useful information about internal dynamic coordination of the organism. Essential problems are nonlinearity and instationarity of the signals, due to the dynamic complexity of the systems. Several time-resolving methods are presented to describe nonlinear dynamic couplings in the time course, particularly during phase transitions. The methods are applied to the recorded signals representing the complex couplings of the physiological subsystems. Phase transitions in these systems are detected by recurrence plots of the instationary signals. The pointwise transinformation and the pointwise conditional coupling divergence are measures of the mutual interaction of the subsystems in the state space. If the signals show marked rhythms, instantaneous frequencies and their shiftings are demonstrated by time frequency distributions, and instantaneous phase differences show couplings of oscillating subsystems. Transient signal components are reconstructed by wavelet packet time selective transient reconstruction. These methods are useful means for analyzing coupling characteristics of the complex physiological system, and detailed analyses of internal dynamic coordination of subsystems become possible. During phase transitions of the functional organization (a) the rhythms of the central neuronal activities and the peripheral systems are altered, (b) changes in the coupling between CBS neurons and cardiovascular signals, respiration and the EEG, and (c) between NTS neurons (influenced by baroreceptor afferents) and CBS neurons occur, and (d) the processing of baroreceptor input at the NTS neurons changes. The results of this complex analysis, which could not be done formerly in this manner, confirm and complete former investigations on the dynamic organization of the CBS with its changing relations to peripheral and other central nervous subsystems.

Interbeat interval variability in isolated working rat hearts at various dynamic conditions and temperatures.

This study quantifies the effect of afterload and preload changes and of temperature on interbeat interval variability of the intact isolated heart. Ventricular pressure pulse records were obtained from isolated working rat hearts. The variability of interbeat intervals (BIs) was quantified by C90, the central 90% range of the BIs during 10 min periods; predominant frequencies were searched for by power spectral analysis. At 37 degrees C the BI lengths oscillated pseudo-randomly with BI variability C90< or =4 ms. Alternating signs of consecutive BI differences were predominant, and no peaks. were seen in the power spectra. Changes in end-diastolic and aortic pressure had little effect. From 37 degrees C down to 27 degrees C the variability increased about sevenfold, run phase length became randomly distributed, and individual, time-variant peaks occurred in the power spectra. BI variability vanished during atrial pacing. We conclude that: (1) effective mutual synchronization with minimal fluctuation happens within the sino-atrial node of intact rat hearts at body temperature, and synchronization is not affected even by extreme changes in pre- and afterload, (2) the sino-atrial node is the sole source of BI variability in the intact isolated rat heart, (3) low temperature hampers this functional organization which can be reestablished by sinus node accelerating agents (isoprenaline, theophylline), (4) decreasing frequency by N6-Cyclopentyladenosine at normothermia also increases BI variability but less pronouncedly than hypothermia does.

Simultaneous changes of rhythmic organization in brainstem neurons, respiration, cardiovascular system and EEG between 0.05 Hz and 0.5 Hz.

Several neurons from different regions of the brainstem of anesthetized dogs were simultaneously recorded, together with various parameters of the cardiovascular system, respiration, efferent sympathetic neural activities and cortical activity. Often rhythmic changes of activity in the range 0.05-0.5 Hz could be observed in the simultaneously recorded signals. The rhythms were analysed in time domain and by power spectra and their changes depicted over the time. The most striking rhythms between 0.05 Hz and 0.5 Hz are the respiratory rhythm and those rhythms that originate in reticular neurons of the common brainstem system as well as their respective harmonics, i.e. the ranges around the integer multiple frequencies of these basic rhythms. The observed oscillations can vanish and reappear at times. Frequencies of basic oscillations and harmonics and their amplitudes are subject to distinct slow modulations. These modulations can have irregular as well as regular courses. The different rhythms can appear separately or simultaneously in the single signals. The most important phenomenon to be observed is that the rhythms mutually influence their frequencies, which follows the rules of 'relative coordination' as described by E. v. Holst. Such changes of rhythmic activities generally also concern the ranges of harmonics of the basic rhythms. Rhythmic influences on peripheral functional systems, e.g. the cardiovascular system, are most distinct at times when the different rhythms overlap in their frequency ranges. This holds not only for the ranges of basic frequencies, but also for the ranges of their harmonics. Further it was found that rhythms with the same basic frequencies may not only appear simultaneously, but also at various times in the different functional systems. The temporal course of changes of these rhythms, their interactions and their influence on the processing of cardiac rhythmic neuronal discharge patterns is demonstrated. The meaning of the mutually influencing rhythms for the functional organization of central nervous structures is discussed.

[Evaluation of possible measuring errors from overlaying pressure components in invasive blood pressure recording with external transducers]. / Beurteilung möglicher Messfehler aus sich überlagernden Druckkomponenten bei der invasiven Blutdruckmessung mit externen Druckaufnehmern.

Invasive arterial blood pressure measurement using external transducers is a routine measure in intensive care medicine and anaesthesiology. Despite the frequency of its use, measuring errors may occur that can strongly affect the significance of the results. The error with the greatest influence on blood pressure measurement arises from an inadequate dynamic behaviour of the measuring chain, and has been investigated in numerous publications. Measuring errors due to hydrostatic and dynamic pressure have not been considered to date. The present investigation describes an analysis of such measuring errors and possible ways of avoiding them. A side-hole catheter permits pressure measurements to be made without the measuring error caused by dynamic pressure behaviour. However, both analytical and experimental studies revealed that, since the velocities involved are small, this error is negligible in blood pressure measurements, and the increased cost of such catheters is therefore not justified. Measuring error due to hydrostatic pressure can be eliminated by using a zero point compensator. Such a compensator that permits vertical changes in the position of the patient without the need for manual resetting of the zero point has now been developed. However, the clinical test showed that the advantages offered by the zero point compensator again do not justify the increased cost. Furthermore, lateral changes in the patient's position during its use can lead to erroneous measurements.

Influences of mandatory breathing on rhythmical components of electrodermal activity.

We investigated whether rhythmical components of electrodermal activity (EDA) can be influenced by voluntary modification of the respiratory frequency. Fifty-five volunteers participated in an experiment with nine mandatory sections of cycle times between 3.1 s and 12.2 s. The cycle time of the rhythmical EDA components often differed considerably from respiratory cycle time. ANOVA yielded that both cycle time and position within the section had an effect on the EDA power of the mandatory cycles (P < 0.05). No significant interaction between effects of section and of position was discovered (P > 0.1). A separate analysis of the cycle times of the rhythmical EDA components revealed integer relationship with the respiratory cycle times. Thus, voluntary changes in the respiratory frequency can influence occurrence and cycle time of rhythmical EDA components in a way similar to sliding coordination in the sense of E. von Holst.

[Incidence of contralateral inguinal hernias in infancy and childhood]. / Inzidenz von kontralateralen Leistenhernien im Säuglings- und Kindesalter.

Inguinal hernia is a frequent surgical disease during infancy, occurring in 1 to 2% of all mature newborns and rise up to 30% of all premature babies. In 9.5% a contralateral hernia is found after unilateral operation. In our own patients this rate was 5.6%. The development of a contralateral hernia was significantly more often found in boys than in girls. If the hernia occurred during the first two months of life, a contralateral hernia developed later highly significant (p > 0.0001). Within the first two postoperative years the second hernia arose in 84.9%. We recommended to routinely operation for a contralateral hernia in all children younger than two months.

Electrodermal activity reveals respiratory and slower rhythms of the autonomic nervous system.

Electrodermal Activity (EDA) was measured in 55 subjects during (1) an alarm reaction, (2) mental load, and (3) physical load. In 34 subjects, not only was a transient response observed, but also, oscillatory patterns characterizing short term variations of EDA. The durations of these oscillations varied between 3-16 s. Most commonly, they were approximately within the frequency range of respiration, or lower, at about 0.1 Hz. The EDA-rhythms were also related to the arterial blood pressure. They were, however, not strictly synchronized with respiration or with the blood pressure waves. We conclude that assessment of EDA in combination with fluctuations of the heart rate, and also, if possible, arterial blood pressure, may turn out to be a useful tool in the evaluation of the interaction between different regulatory processes that are realized by the common brainstem system.

Relationship between rhythmic discharge patterns of neurons in the central nucleus of the amygdala, blood pressure fluctuations and cortical activity.

In the discharge sequences recorded from single neurons in the central nucleus of the amygdala of chronically instrumented awake cats, rhythmical patterns with period durations of 5-12 s were observed. At the same time blood pressure and the degree of synchronisation of the EEG showed similar period fluctuations with positive correlation to neuronal activity. It is proposed that the central amygdaloid nucleus uses rhythmic patterns to coordinate somatomotor and vegetative systems.

Cardiac rhythmic patterns in neuronal activity related to the firing rate of the neurons: II. Amygdala neurons of cats.

Neurons of the central and basal part of the amygdala complex were recorded in conscious, freely moving cats. These neurons have various cardiac rhythmic discharge patterns (CRDPs) which are estimated by post-event-time histograms (PETH). When the firing level of the neurons changed, the CRDPs were modulated. These modulations became obvious, when 'partial' PETHs of the neuronal activity were constructed according to the discharge level of the neurons. With changes of the neuronal discharge level different types of CRDPs were observed, interlaced in time during recordings of the same neuron. In 'total' PETHs, taken from the continuous periods of neuronal activity, cardiac rhythm was hidden or often was not so clearly visible as in 'partial' PETHs, taken at different discharge levels. As in case of neurons of the nucleus tractus solitarii (NTS) and for brainstem reticular neurons, amygdala neurons exhibited modulations of CRDPs as their activity level changed. The results indicate that the processing of activity patterns in these neurons depends on their activity level and functional organization, which is essentially dependent on afferent signals and influences from central structures reaching these neurons.

Cardiac rhythmic patterns in neuronal activity are related to the firing rate of the neurons: I. Brainstem reticular neurons of dogs.

Cardiac rhythmic discharge patterns (CRDP) of brainstem reticular neurons in anesthetized dogs were estimated by ECG-triggered post-event-time histograms (PETH). Modulations of the CRDP occur, whenever the firing levels of the neurons slowly change with periods longer than the cardiac cycle. Therefore, in the activity of one and the same neuron different types of CRDP can occur interlaced in time. 'Partial' PETHs calculated according to the discharge level of the neurons make these various CRDP obvious. On the other hand, the CRDP are not always so clear in the 'total' PETHs, taken from the continuous periods of activity. The meaning of these different CRDP for regulatory processes of the organism is discussed. We study the processing of the easily identifiable signal in neuron activity, i.e., cardiac rhythm, to illustrate how signal processing depends on the momentary activity level of the neurons which is influenced by other afferent signals and by inflows from central structures reaching the neurons.

Urethral lengthening with anterior bladder wall flap for urinary incontinence: a new approach.

Urethral irregularity (impeding catheterization) and failure to achieve continence are common complications in surgery for urinary incontinence. We describe a surgical technique using an anterior bladder wall flap that is sutured to the posterior wall in an onlay fashion creating a flap valve mechanism. Experimental work in dogs demonstrated a significant increase in the leak point pressure in the surgical group when compared to controls (p = 0.019). Voiding cystourethrography and bladder inspection demonstrated an anterior flap valve with no fistula formation in all animals. Histological examination showed a viable anterior bladder wall flap in all cases. This technique was then applied to 6 patients with neurogenic bladder and low urethral resistance that failed to resolve with medical treatment. Urinary continence was achieved in 4 patients. In 1 patient a vesicourethral fistula developed 3 months postoperatively, since the mother failed to catheterize for 12 hours. This technique is a useful alternative in the treatment of urinary incontinence.