The initial maturation status of marmoset testicular tissues has an impact on germ cell maintenance and somatic cell response in tissue fragment culture

Successful in vitro spermatogenesis was reported using immature mouse testicular tissues in a fragment culture approach, raising hopes that this method could also be applied for fertility preservation in humans. Although maintaining immature human testicular tissue fragments in culture is feasible for an extended period, it remains unknown whether germ cell survival and the somatic cell response depend on the differentiation status of tissue. Employing the marmoset monkey (Callithrix jacchus), we aimed to assess whether the maturation status of prepubertal and peri-/pubertal testicular tissues influence the outcome of testis fragment culture. Testicular tissue fragments from 4- and 8-month-old (n = 3, each) marmosets were cultured and evaluated after 0, 7, 14, 28 and 42 days. Immunohistochemistry was performed for identification and quantification of germ cells (melanoma-associated antigen 4) and Sertoli cell maturation status (anti-Müllerian hormone: AMH). During testis fragment culture, spermatogonial numbers were significantly reduced (P < 0.05) in the 4- but not 8-month-old monkeys, at Day 0 versus Day 42 of culture. Moreover, while Sertoli cells from 4-month-old monkeys maintained an immature phenotype (i.e. AMH expression) during culture, AMH expression was regained in two of the 8-month-old monkeys. Interestingly, progression of differentiation to later meiotic stage was solely observed in one 8-month-old marmoset, which was at an intermediate state regarding germ cell content, with gonocytes as well as spermatocytes present, as well as Sertoli cell maturation status. Although species-specific differences might influence the outcome of testis fragment experiments in vitro, our study demonstrated that the developmental status of the testicular tissues needs to be considered as it seems to be decisive for germ cell maintenance, somatic cell response and possibly the differentiation potential.

Raman micro-spectroscopy analysis of different sperm regions: a species comparison

STUDY QUESTION

Is Raman micro-spectroscopy a valid approach to assess the biochemical hallmarks of sperm regions (head, midpiece and tail) in four different species?

SUMMARY ANSWER

Non-invasive Raman micro-spectroscopy provides spectral patterns enabling the biochemical characterization of the three sperm regions in the four species, revealing however high similarities for each region among species.

WHAT IS KNOWN ALREADY

Raman micro-spectroscopy has been described as an innovative method to assess sperm features having the potential to be used as a non-invasive selection tool. However, except for nuclear DNA, the identification and assignment of spectral bands in Raman-profiles to the different sperm regions is scarce and controversial.

STUDY DESIGN SIZE, DURATION

Raman spectra from head, midpiece and tail of four different species were obtained. Sperm samples were collected and smeared on microscope slides. Air dried samples were subjected to Raman analysis using previously standardized procedures.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Sperm samples from (i) two donors attending the infertility clinic at the Centre of Reproductive Medicine and Andrology; (ii) two C57BL/6 -TgN (ACTbEGFP) 1Osb adult mice; (iii) two adult Cynomolgus monkeys (Macaca fascicularis) and (iv) two sea urchins (Arbacia punctulata) were used to characterize and compare their spectral profiles. Differences and similarities were confirmed by principal component analysis (PCA).

MAIN RESULTS AND THE ROLE OF CHANCE

Several novel region-specific peaks were identified. The three regions could be differentiated by distinctive Raman patterns irrespective of the species. However, regardless of the specie, their main spectral pattern remains mostly unchanged. These results were corroborated by the PCA analysis and suggest that the basic constituents of spermatozoa are biochemically similar among species.

LIMITATIONS REASONS FOR CAUTION

Further research should be performed in live sperm to validate the detected spectral bands and their use as markers of distinctive regions.

WIDER IMPLICATIONS OF THE FINDINGS

Raman peaks that have never been described in the sperm cell were detected. Particularly important are those that are unique to the midpiece as they might be a reference to the identification of sperm mitochondria, whose function is highly correlated with that of sperm. In the future, Raman micro-spectroscopy has the potential to be applied in assessment of male fertility.

LARGE SCALE DATA

N/A.

STUDY FUNDING AND COMPETING INTEREST(S)

This work was supported by BMBF project 'Sperm Ident' (FKZ:13N13024) and the DAAD-CRUP bilateral exchange program (AI A06/16-57213087). S.A. is a recipient of a fellowship from the Portuguese foundation for science and technology (FCT-SFRH/BPD/110160/2015) and R.DC. is a recipient of a DAAD PhD stipend (91590556). There is no competing interest.

[Antagonistic function of the heart muscle : Part II: Clinical implications]

In the hypertrophic heart the myostructural afterload in the form of endoepicardial networks is predominant, which enhances myocardial hypertrophy. The intrinsic antagonism is derailed. Likewise, the connective tissue scaffold, i.e. the stromatogenic afterload, is enriched in the response to the derailment of antagonism in a hypertrophic heart up to regional captivation of the heart musculature. Due to the selective susceptibility of the auxotonic, contracting oblique transmural myocardial network for low dose negative inotropic medication, this promises to attenuate progress in myocardial hypertrophy. Volume reduction surgery is most effective in reducing wall stress as long as the myocardium is not critically fettered by fibrosis. The use of external mechanical circulatory support is then effective if the heart is supported in its resting mode, which means around a middle width and at minimal amplitude of motion. The takotsubo cardiomyopathy might possibly reflect an isolated, extreme stimulation of the intrinsic antagonism as a response to hormonally induced sensitization of the myocardium to catecholamine. A particular significant conclusion with respect to the diseased heart is that clinical diagnostics need new impulses with a focus on the analysis of local motion patterns and on myocardial stiffness reflecting disease-dependent antagonistic intensity. This would become a relevant diagnostic marker if corresponding (noninvasive) measurement techniques would become available.

[The antagonistic function of the heart muscle sustains the autoregulation according to Frank and Starling : Part I: Structure and function of heart muscle]

In the tradition of Harvey and according to Otto Frank the heart muscle structure is arranged in a strictly tangential fashion hence all contractile forces act in the direction of ventricular ejection. In contrast, morphology confirms that the heart consists of a 3-dimensional network of muscle fibers with up to two fifths of the chains of aggregated myocytes deviating from a tangential alignment at variable angles. Accordingly, the myocardial systolic forces contain, in addition to a constrictive also a (albeit smaller) radially acting component. Using needle force probes we have correspondingly measured an unloading type of force in a tangential direction and an auxotonic type in dilatative transversal direction of the ventricular walls to show that the myocardial body contracts actively in a 3-dimensional pattern. This antagonism supports the autoregulation of heart muscle function according to Frank and Starling, preserving ventricular shape, enhances late systolic fast dilation and attenuates systolic constriction of the ventricle wall. Auxotonic dilating forces are particularly sensitive to inotropic medication. Low dose beta-blocker is able to attenuate the antagonistic activity. All myocardial components act against four components of afterload, the hemodynamic, the myostructural, the stromatogenic and the hydraulic component. This complex interplay critically complicates clinical diagnostics. Clinical implications are far-reaching (see Part II, https://doi.org/10.1007/s00059-018-4735-x).

Pneumatic Distension of Ventricular Mural Architecture Validated Histologically

Purpose: There are ongoing arguments as to how cardiomyocytes are aggregated together within the ventricular walls. We used pneumatic distension through the coronary arteries to exaggerate the gaps between the aggregated cardiomyocytes, analyzing the pattern revealed using computed tomography, and validating our findings by histology. Methods: We distended 10 porcine hearts, arresting 4 in diastole by infusion of cardioplegic solutions, and 4 in systole by injection of barium chloride. Mural architecture was revealed by computed tomography, measuring also the angulations of the long chains of cardiomyocytes. We prepared the remaining 2 hearts for histology by perfusion with formaldehyde. Results: Increasing pressures of pneumatic distension elongated the ventricular walls, but produced insignificant changes in mural thickness. The distension exaggerated the spaces between the aggregated cardiomyocytes, compartmenting the walls into epicardial, central, and endocardial regions, with a feathered arrangement of transitions between them. Marked variation was noted in the thicknesses of the parts in the different ventricular segments, with no visible anatomical boundaries between them. Measurements of angulations revealed intruding and extruding populations of cardiomyocytes that deviated from a surface-parallel alignment. Scrolling through the stacks of tomographic images revealed marked spiraling of the aggregated cardiomyocytes when traced from base to apex. Conclusion: Our findings call into question the current assumption that cardiomyocytes are uniformly aggregated together in a tangential fashion. There is marked heterogeneity in the architecture of the different ventricular segments, with the aggregated units never extending in a fully transmural fashion. Key Points: • Pneumographic computed tomography reveals an organized structure of the ventricular walls.• Aggregated cardiomyocytes form a structured continuum, with marked regional heterogeneity.• Global ventricular function results from antagonistic forces generated by aggregated cardiomyocytes. Citation Format: • Burg MC, Lunkenheimer P, Niederer P et al. Pneumatic Distension of Ventricular Mural Architecture Validated Histologically. Fortschr Röntgenstr 2016; 188: 1045 - 1053.

UVB irradiation as a tool to assess ROS-induced damage in human spermatozoa

One of the consequences of oxygen metabolism is the production of reactive oxygen species (ROS) which in a situation of imbalance with antioxidants can damage several biomolecules, compromise cell function and even lead to cellular death. The particularities of the sperm cell make it particularly vulnerable to ROS attack compromising its functionality, mirrored in terms of fertility outcome and making the study of the origin of sperm ROS, as well as the alterations they cause very important. In the present work, we used UVB irradiation, an easy experimental approach known as a potent inducer of ROS formation, to better understand the origin of ROS damage without any confounding effects that usually exist in disease models in which ROS are reported to play a role. To address these issues we evaluated sperm mitochondrial ROS production using the Mitosox Red Probe, mitochondrial membrane potential using the JC-1 probe, lipid peroxidation through BODIPY probe and vitality using PI. We observed that UVB irradiation leads to an increase in sperm mitochondrial ROS production and lipid peroxidation that occur previously to an observable mitochondrial dysfunction. We concluded that sperm UVB irradiation appears to be a good and easily manipulated in vitro model system to study mitochondria-induced oxidative stress in spermatozoa and its consequences, which may be relevant in terms of dissecting the action pathways of many other pathologies, drugs and contaminants, including endocrine disruptors.

Intrathoracic implantation of a continuous flow left ventricular assist device--the microdiagonal blood pump

AIM

All existing ventricular assist devices are associated with a considerable number of serious complications. We report on our first animal tests with a newly developed microdiagonal blood pump (MDP).

METHODS

Six female calves underwent MDP implantation. The inflow and outflow conduit were anastomosed to the left atrium and the descending aorta. The MDP was placed in the left phrenicocostal sinus. Pump flow was adjusted to 2-3 L/min. Hemodynamic and echocardiographic data as well as blood samples were measured over the test period of 7 days. Thereafter, all internal organs and the pump were explanted for thorough examination.

RESULTS

Mean arterial (90.5+/-12.1102.7+/-8.7 mmHg) and mean pulmonary arterial (17.3+/-2.420.6+/-2.7 mmHg) pressures remained stable during the test period. Cardiac output (5.4+/-0.5 = or >3.5+/-0.5 L/min) decreased postoperatively due to partial unloading of the heart. Left ventricular end-diastolic (4.4+/-0.5= or >3.8+/-0.4 cm) and end-systolic (3.4+/-0.5 =or >2.9+/-0.4 cm) diameters decreased after MDP implantation and did not change during the test period. Mean number of platelets (550+/-57 =or >350+/-86 x 103/microL) and hemoglobin (13.2+/-1.3 = or >11.9+/-0.8 g/dL) decreased perioperatively due to surgical reasons and recovered in the postoperative course. Free hemoglobin was slightly enhanced in the postoperative course.

CONCLUSION

Our results demonstrate that the MDP is suitable for intrathoracic implantation and provides a reliable left ventricular unloading.

The forces generated within the musculature of the left ventricular wall

OBJECTIVES

To test the hypothesis that two populations of myocardial fibres-fibres aligned parallel to the surfaces of the wall and an additional population of fibres that extend obliquely through the wall-when working in concert produce a dualistic, self stabilising arrangement.

METHODS

Assessment of tensile forces in the walls of seven porcine hearts by using needle probes. Ventricular diameter was measured with microsonometry and the intracavitary pressure through a fluid filled catheter. Positive inotropism was induced by dopamine, and negative inotropism by thiopental. The preload was raised by volume load and lowered by withdrawal of blood. Afterload was increased by inflation of a balloon in the aortic root. The anatomical orientation of the fibres was established subsequently in histological sections.

RESULTS

The forces in the fibres parallel to the surface decreased 20-35% during systolic shrinkage of the ventricle, during negative inotropism, and during ventricular unloading. They increased 10-30% on positive inotropic stimulation and with augmentation in preload and afterload. The forces in the oblique transmural fibres increased 8-65% during systole, on positive inotropic medication, with an increase in afterload and during ventricular shrinkage, and decreased 36% on negative inotropic medication. There was a delay of up to 147 ms in the drop in activity during relaxation in the oblique transmural fibres.

CONCLUSION

Although the two populations of myocardial fibres are densely interwoven, it is possible to distinguish their functions with force probes. The delayed drop in force during relaxation in obliquely oriented fibres indicates that they are hindered in their shortening to an extent that parallels any increase in mural thickness. The transmural fibres, therefore, contribute to stiffening of the ventricular wall and hence to confining ventricular compliance.

A critical evaluation of results of partial left ventriculectomy

BACKGROUND

Because of the variation in the surgical procedures designed to reduce ventricular radius, along with differences in hospital care, it is difficult to disentangle the factors that may contribute to the success or failure of the partial left ventriculectomy.

METHODS AND RESULTS

We undertook partial left ventriculectomy in 18 patients, 10 suffering from idiopathic dilated cardiomyopathy and 8 from ischemic heart disease. We assessed the amount of reduction in wall stress, the systolic thickening of the ventricular wall, and the extent of connective tissue in the excised segment of the wall. Of the overall group, six patients died, three from infarction, one of stroke, one with asystole, and one with ventricular fibrillation. The mean decrease in measured mesh tension was 40% (p < 0.001). Most patients exhibited improvements postoperatively in terms of the systolic thickening of the posterior and superior free walls of the left ventricle. In those in whom the events could be monitored, life-threatening arrhythmias posed complications in three of four patients with ischemic heart disease, and in two of six patients suffering from idiopathic dilated cardiomyopathy. In one patient, death was associated with a transmural alignment of fibrous tissue.

CONCLUSIONS

Our measured reductions in myocardial mesh tension were in keeping with the anticipated theoretical reduction in wall stress expected from partial ventriculectomy. The basic concept underscoring surgical maneuvers to reduce ventricular radius, therefore, is sound. A potential trap is the resection of the marginal artery. Critical myofibrosis was a rare complication. Arrhythmias, which are common, can successfully be treated by implantation of antitachycardic and defibrillatory devices.

Treatment strategy and perioperative risk in patients with idiopathic thrombocytopenic purpura undergoing cardiac surgery

Patients suffering from idiopathic thrombocytopenic purpura undergoing cardiac surgery with extracorporeal circulation may be at increased risk for postoperative bleeding complications. Therefore, different treatment strategies, such as conservative treatment, splenectomy, transfusion of platelet concentrates and therapy with immunoglobulins have been proposed. We report on our experiences with preoperative immunoglobulin treatment in selected patients with special regard on the optimal dosage.

Does a suitable animal model for research on partial left ventriculectomy exist? Animal models for PLV

Partial left ventriculectomy is a new surgical option quickly introduced into clinical use worldwide for treating end-stage heart failure in patients with dilated cardiomyopathy. Due to the overwhelming success of this new kind of surgical treatment for dilated cardiomyopathy, experimental research on the physiological and pathophysiological basis was initially not performed. Now, demands for an appropriate animal model have arisen more and more since the outcome of patients treated by partial left ventriculectomy has differed considerably. This review summarizes available experimental models for heart failure in large animals, and discusses their suitability for research on partial left ventriculectomy.

Late ventricular structure after partial left ventriculectomy

Nine months after partial ventriculectomy, a 53-year-old man died of progressive heart failure. His heart was examined to determine the alignment of the muscle fibers around the ventricular scar, which was 11 cm long, 1.3 cm thick and 4 cm wide. The scar reached 2 to 12 mm beyond the surgical suture line. The fibers in the middle and subendocardial layers were malaligned, resulting in convergence, compression and regional necrosis.

Preoperative immunoglobulin treatment in patients with Werlhof's disease undergoing cardiac operation

BACKGROUND

Patients with Werlhof's disease and undergoing a cardiac surgical procedure with cardiopulmonary bypass are at increased risk for bleeding complications. We report the usefulness of preoperative immunoglobulin treatment in selected patients.

METHODS

Between May 1995 and July 1998, 10 patients with Werlhof's disease underwent a cardiac surgical procedure with cardiopulmonary bypass in our department. Five patients with mean platelet counts of less than 80x10(9)/L received immunoglobulin therapy preoperatively (group 1). The other 5 patients with mean platelet counts higher than 80x10(9)/L were not so treated (group 2).

RESULTS

In group 1, mean platelet count increased from 54x10(9)/L 5 days before operation to 112x10(9)/L after immunoglobulin treatment (p = 0.018) and did not fall to less than 60x10(9)/L postoperatively. Patients in group 1 received 16 units of packed red blood cells and 5 units of platelet concentrate. Patients in group 2 required 24 units of packed red blood cells, 5 units of platelet concentrate, and 23 units of fresh frozen plasma. Only 1 patient (group 2) had a surgical bleeding complication that required reexploration. Mean drainage loss was 1,100 mL in group 1 and 1,210 mL in group 2.

CONCLUSIONS

Our data demonstrate that immunoglobulin treatment of patients with Werlhof's disease and mean platelet counts of less than 80x10(9)/L significantly augments platelet counts preoperatively. It may be useful in selected patients.

Immediate effects of partial left ventriculectomy on left ventricular function

BACKGROUND

Attempts to prolong life or to improve the quality of life by partial left ventriculectomy in patients suffering from dilated cardiomyopathy have yielded strikingly variable results in leading surgical centers.

HYPOTHESIS

The outcome of patients after partial left ventriculectomy depends on intraoperative myocardial protection together with appropriate long-term pharmacotherapy. We further assume that partial removal of the fibrotic ventricular wall may lead to a particularly inhomogeneous pattern of wall stress, giving rise to the potential of a paradoxical increase in wall stress and the creation of arrhythmogenic foci.

METHODS

During surgery in 24 patients, local mesh tension was measured using needle-force probes in up to five sites within the left ventricular wall before and after resection of the interpapillary mural segment. The data were used to calculate regional peak developed force and to identify any differences in the timing of local mechanical activity between the measured regions.

RESULTS

Mean decrease in regional wall stress was 42% (76 sites of measurement). However, we discovered a paradoxical increase of 42% in 18 sites of measurement. The time delay in the onset of force development between the measured regions prior to surgery was 0 msec in 10 patients, up to 30 msec in 7 patients, and beyond 80 msec in 7 patients. After resection, the time delay increased considerably in incidence and duration.

CONCLUSION

Ventriculectomy is an effective means of reducing wall stress. The unexpectedly high incidence of inhomogeneities in wall stress after asymmetrical surgical ventricular remodeling, currently typical for the classical Batista procedure, together with the asynchronous regional ventricular function that we found to increase after partial left ventriculectomy, needs further elucidation by electrophysiological investigations.

Inhomogeneities in wall stress measured by microergometry in the heart muscle in situ

Microergometry is a method which we have developed as a tool to measure local mesh-tension within the myocardial weave at any measuring site of both ventricles and the septum on the beating heart in situ. In a mapping procedure on pig and dog hearts, both in control conditions and in the hypertrophied state after aortic banding, local mesh-tension was measured in several areas and in up to eight depths proceeding from the epicardium to the endocardium: Probe-to-fibre coupling is definitely more stable in the canine myocardium than in the porcine heart muscle, probably due to a more effective connective tissue fettering of the canine myocardial weave. The observed longitudinal gradient, with the highest tension in the base, of control dog hearts was levelled out in the hypertrophied hearts. Furthermore, in control dog hearts mesh-tension in the subepi- and subendocardial layers was higher than in the midlayers. This pronounced midlayerhypotension was smoothed in the hypertrophied hearts. Further studies will be dedicated to the question of whether the impact of ventricular size and shape on intersegmental stress transmission is determined by the Frank-Starling mechanism alone or whether protracted remodelling processes on the level of the local fibre weave cause slow coupling alterations.

A silicone rubber mould of the heart

The macroscopical structure of the ventricular myocardium has been an unsolved problem since the XVIth century, when Anatomy started as an authentic science. Since then the spatial organization of the myocardial fibres has represented, as Pettigrew says, "an arrangement so unusual and perplexing, that it has long been considered as forming a kind of Gordian knot in Anatomy. Of the complexity of the arrangement I need not speak further than to say that Vesalius, Albinus, Haller and De Blainville, all confessed their-inability to unravel it". What is shown in the present paper is the result of an anatomical work, developed over 43 years, by means of which it has been shown that the ventricular myocardial mass consists of a band, curled in a helical way, which extends from the pulmonary artery to the aorta. This is illustrated by a silicone rubber model cast from an actual unrolled myocardial band.

The heart muscle's putative "secondary structure'. Functional implications of a band-like anisotropy

Opinions are divided as to whether the rope-like secondary structure, which Torrent-Guasp dissected out of the myocardial body by the blunt unwinding technique (BUT) reveals some kind of functional compartmentation of the heart muscle. The myocardial fibres are aligned parallel to the fibre disruption (cleavage) plane, along which the band has been prepared but they are not necessarily aligned parallel to the long axis of the band. Inconsistencies in the myocardial rope model arise from the obligatory zones of transmural inflection, which are obvious in the base and the apex of both ventricles. They are, however, merely discernible in the midzone of the left ventricular cone. The investigator experienced in BUT knows that the cleavage plane is not unique. We doubt the assumption that the rope structure is the predominant stress transmission pathway, because the fibre strand peel-off technique (SPOT) delivers irregular fibre disruption planes which are definitely different from those which Torrent-Guasp prepares. The rope-like fibre arrangement could be just a redundant structure, a remnant of past developmental steps without, however, any functional implication to the human heart. On the other hand, peeling-off fibre strands from the ventricular wall produces deeply perforating, i.e., oblique transmurally grooved surfaces. Putative functions of force transmission in an oblique transmural direction are (1) ventricular dilation as a function of the variable inclination angle with respect to the epicardial surface, (2) monitoring of ventricular wall stress and ventricular size and (3) segmental stiffening which could serve other dependent segments as a punctum fixum.

The assessment of intramural stress alignment on the beating heart in situ using micro-ergometry: functional implications

The main local stress transmission pathways in the left ventricular base, midportion and apex in up to seven layers have been assessed in normal dog and porcine hearts, in hypertrophied dog hearts, and in three pig hearts having undergone a temporary left ventricular outflow stricture. The rotational sensitivity of needle force probes was used to determine the focal surface-parallel direction of the myocardial tension vector. In all places investigated the orientation of the force transmission pathways differs slightly from the morphologically determined fibre alignment. Vector rotation upon an axis normal to the epicardial surface is definitely tempered as compared to fibre rotation. Alterations in the force transmission pathways assessed in hypertrophied dog hearts by micro-ergometry qualitatively confirm structural remodelling in so far as an irregularity in the transmural rotation of the main stress vector was found. The measured disparities between the alignment of the myocardial fibre weave and the direction of stress transmission both in the normal and the diseased heart is widely individual, and hence, scattering of the data is marked. However, it must also be called into consideration that the measured orientation of force vectors is that at the moment of highest developed force, only. Further investigations will elucidate if discrepancies between that force vector and morphology are less pronounced when the vector is averaged over the entire heart cycle.

The heart's fibre alignment assessed by comparing two digitizing systems. Methodological investigation into the inclination angle towards wall thickness

Myocardial contractile pathways which are not aligned strictly parallel to the heart's epicardial surface, give rise to forces which also act in the ventricular dilating direction. We developed a method which allows us to assess any fibre orientation in the three-dimensional myocardial weave. Decollagenized hearts were prepared by peeling-off fibre strands, following their main fibre orientation down to near the endocardium. In the subepicardium the strands followed a course more or less parallel to the epicardium, whereas from the mid-wall on they tended to dive progressively deeper into the wall. The preparation displays more or less rugged surfaces rather than smooth layers. The grooves and crests on the exposed surfaces were sequentially digitized by two methods: (1) Using a magnet tablet (3 Draw Digitizer System, Polhemus, Cochester VTO 5446, USA) on a dilated pig heart we manually followed the crests using a stylus, handling each groove and crest as an individual contractile pathway. (2) A constricted cow heart was digitized using a contact-free optical system (opto TOP, Dr. Breuckmann, Meersburg, Germany), which is based on the principle of imaging triangulation. Using specially developed software the inclination angles of selected crests and grooves with respect to the epicardial surface were calculated. The two digitizing methods yield comparable results. We found a depth- and side-specific weave component inclined to the epi-endocardial direction. This oblique netting component was more pronounced in the inner 1/3 of the wall than in the subepicardium. The inclination angle probably increases with increasing wall thickness during the ejection period. Manual digitizing is an easy and fast method which delivers consistent results comparable with those obtained by the cumbersome high resolution optical method. The rationales for the assessment of transmural fibre inclination are (1) the putative existence of dilating forces inherent in the myocardial weave and (2) the possible overproportional increase in the oblique transmural weave component during myocardial hypertrophy, which would entail a reduction in efficiency of ventricular performance in terms of haemodynamic work.

Computation of the alignment of myocardial contractile pathways using a magnetic tablet and an optical method

The computation of the inclination angle of myocardial contractile pathways, based on the data from (1) optically and (2) manually digitized hearts is described. The measured raw data comprised: (1) A list epi of points on an "epicardial' surface S. (2) For each selected contractile pathway f, a list of points along the contractile pathway. For any point p on a contractile pathway f, the angle of inclination alpha p = alpha p (p,f,S) is defined to be the angle (in degrees) between the tangent tp = tp(f) to the contractile pathway f at the point p and the tangent plane Tvp to the surface S at the surface point up = v(p,S) which is nearest to p. Thus alpha p is a generalization of the imbrication angle of Streeter. The angle of inclination was computed using two separate numerical methods: (1) A discrete method, applying finite differences to the raw data, to compute the tangents tp and the tangent planes Tvp, after which the results were smoothed. (2) A smoothing method in which the data was first smoothed to obtain an approximation Scpi to the epicardial surface and spline approximations to the contractual pathways f. We describe the results for two typical hearts: a manually digitized dilated pig heart and an optically digitized constricted cow heart. For each heart we first present the depths and angles of inclination of typical contractual pathways and then summarize the results in the form of histograms. The results are discussed in detail in the accompanying paper of Lunkenheimer. Redmann et al. [5], where the digitization methods are also described.

A prospective risk analysis of contemporary thoracic surgery

OBJECTIVE

The results of surgical therapy can only be accurately judged if the patients' characteristics and their impact on the outcome are known. The purpose of this study was to identify the risk factors of contemporary thoracic surgery, which could serve as a basis for a risk-matched comparison of different surgical techniques.

METHODS

The data of 15 patients' undergoing thoracic surgery were prospectively documented. The outcome of the various operative procedures applied was statistically correlated with the access procedure, sex, age, body mass, dignity of underlying disease and six concomitant diseases.

RESULTS

Four patients died within 30 days of surgery (mortality: 2.6%). Morbidity comprising all complications (class I) and morbidity comprising only complications of consequence for postoperative therapy (class II) rose with the number of concomitant diseases (50%/0% with no concomitant disease, 89%/33% with more than three concomitant diseases). Univariate testing identified malignant disease (P = 0.002), male sex (P = 0.003), body mass index of less than 20 and more than 27 kg/m of the expected level according to the Quetelet rule (P = 0.013) and a combination of concomitant respiratory and cardiocirculatory disease (P = 0.022) as being associated with class I morbidity. Male sex was significantly coincident with class II morbidity (P = 0.020). Logistic regression analysis demonstrated that these characteristics also had independent influence on class I morbidity (P = 0.022, P = 0.001, P = 0.023, P = 0.028).

CONCLUSION

It is concluded that these characteristics are important predictors of morbidity of thoracic surgery. If a non-randomized comparison of the outcome of thoracic operations or different access strategies like thoracotomy or thoracoscopy is intended, at least these patient features should be documented and used as a basis for matching pairs.

[Hemo- and cardiodynamic effect of nifedipine in halothane or isoflurane anesthesia. An animal experiment study]

OBJECTIVE

The present experimental study on 16 acutely instrumented dogs was designed to determine the haemo- and cardiodynamic changes after an intravenous infusion of nifedipine during halothane or isoflurane anaesthesia.

METHODS

General anaesthesia was induced with ketamine (10 mg/kg) and fentanyl (0.02 mg/kg) and maintained with fentanyl (0.3 micrograms/kg/min), 3:1 N2O/O2 inhalation mixture, and pancuronium (300 micrograms/kg/h). A left thoracotomy was performed and a needle force probe was placed in the left ventricular wall to measure myocardial force of contraction. A Widney gauge was placed around the left ventricle to measure left ventricular circumference changes. The animals were also monitored with left ventricular tip manometers, pulmonary arterial thermodilution catheters, and femoral arterial and venous catheters. Three hours after instrumentation baseline haemodynamic measurements were performed and repeated 30 min after either halothane 0.8 vol.% (n = 8) or isoflurane 1.5 vol.% (n = 8). Then nifedipine (10 micrograms/kg i.v.) was administered and haemodynamic measurements were repeated.

RESULTS

Both volatile anaesthetic agents caused a decrease in MAP, CO, LVP, LVFS, and dP/dtmax. Heart rate, CVP, PAOP, and the diastolic diameter of the heart did not change with halothane and isoflurane. Isoflurane led to a decrease of SVR that was not seen with the administration of halothane. Nifedipine during halothane anaesthesia caused a further decrease in MAP, SVR, LVP, dP/dtmax, and LVFS compared to the already reduced values with halothane alone. However, SV did not decrease any further. If nifedipine was added to isoflurane a further decrease in CO and SV was observed despite a constant SVR.

CONCLUSION

Halothane, isoflurane and nifedipine are cardiac depressant drugs. Isoflurane induces vasodilation and appears to be less cardiodepressant than halothane in the clinical situation. However, if nifedipine is added, the vasodilation caused by nifedipine offsets its own negative inotropic effect and in parts the cardiac depression of halothane. Combined with isoflurane the vasodilatory effect of nifedipine is insignificant and the negative inotropic effects of both drugs are additive resulting in a profound decrease in SV and CO.

High-frequency oscillation in an adult porcine model

OBJECTIVE

Controversy exists as to whether high-frequency oscillatory ventilation can be used on babies and small laboratory animals only, or whether high-frequency oscillatory ventilation can also be efficient in the adult patient and large (> 65 kg body weight) laboratory animals. Moreover, controversy exists as to whether limitations in high-frequency oscillation efficiency are caused by the size and shape of the bronchial system, by the lack of low impedant intersegmental gas flow in lung parenchyma, or by inappropriate high-frequency ventilators and ancillary hardware. Therefore, our objective in this study using the adult pig as a model of the adult patient was to test whether the adult airway system is suited to the use of high-frequency oscillatory ventilation or whether there are geometrical, structural, or functional limitations to efficient ventilation by high-frequency oscillation.

DESIGN

Prospective, controlled, randomized comparison over 8 to 16 hrs of ventilatory management.

SETTING

Experimental thoracovascular surgery laboratory in a university hospital.

SUBJECTS

Fifteen adult, female, house swine (weight 90 to 140 kg).

INTERVENTIONS

We evaluated the ventilatory effect of a wide range of oscillation frequencies (10-15 to 35-45 Hz), tidal volumes (0.5 to 2.2 mL/kg), and bias flow volumes (10 to 70 L/min) at a mean airway pressure of 12 +/- 1 cm H2O in anesthetized and relaxed pigs who did not have lung injury.

MEASUREMENTS AND MAIN RESULTS

Arterial blood gases are mainly dependent on tidal volume, frequency, and mean airway pressure. A threshold bias flow volume of 35 +/- 5 L/min is required to prevent CO2 rebreathing. In the group of lightweight animals (65 to 99 kg), the most efficient frequency band for CO2 elimination was approximately 25 Hz. The most efficient frequency band for arterial oxygenation was found to vary between individuals more than the most efficient frequency band for CO2 elimination. In the group of heavy animals (100 to 140 kg), no most efficient mean frequency could be assessed, probably because the excitation system was limited. We confirmed that tidal volume on its own had an effect on CO2 elimination ("tidal-volume effect"), although CO2 elimination was mainly determined by the product of tidal volume and oscillation frequency (oscillated minute volume), at least up to a critical frequency. Beyond that frequency, CO2 elimination could not be enhanced. The most efficient mean airway pressure in unimpaired lungs was assessed at 12 +/- 1 cm H2O.

CONCLUSIONS

Adult pigs with a body weight in the range of the weight of clinical adult patients can be ventilated by high-frequency oscillation at tidal volumes smaller than, equal to, or slightly more than anatomical deadspace. The most efficient frequency for gas exchange varied between individuals. Tidal volume had an enhancing effect on CO2 elimination. The frequency dependency of PaO2 may have been related to a frequency-dependent structural remodeling of the airway system, which occurred even though the mean airway pressure was kept constant. These results demonstrate that failure of adequate ventilation by high-frequency oscillation is caused by a) CO2 rebreathing, b) the avoidance of an appropriate alveolar recruitment strategy, and c) an underpowered, high-frequency ventilatory system (oscillator) that is unable to deliver appropriate pressure oscillations. These limitations led to insufficient CO2 elimination and/or inadequate arterial oxygenation.

[Ventilation by high frequency oscillations in adults. An experimental study of conditions and methods]

A hydraulic pump with an adjustable stroke delivering up to 145 ml at 1 to 45 Hz has been used to ventilate adult pigs of a weight between 60 and 140 kg. After tracheotomy the curarized animals were connected to the pump by a metallic tube through which a bias flow was directed. This flow (FiO2 0.35) was humidified by a special ceramic device and aspirated at the distal end of the tube. It was demonstrated that under these conditions gaz exchange was well maintained with oscillations between 15 and 35 Hz. Higher frequencies were needed for the heavier animals. Blood gas measurements of samples from segmental pulmonary veins demonstrated regional differences in gas exchange. These could be modified by adjusting the oscillation frequency. Reinhalation of gas could be prevented by an increase of the bias flow. Alveolar recruitment by initial pulmonary inflation by a pressure of 18 +/- 2 cm H2O is required for adequate oxygenation. Maintenance of adequate elimination of CO2 required a bias flow of 35 +/- 5 l/min. Mean pressure in the airways was maintained at 12 +/- 1 cm H2O. This pressure determines the value of PaO2. Ordinary endotracheal tubes tend to collapse during the sucking phase of the pressure cycle. Rigid or armed tubes are required. They must allow for aspiration of the bias flow from the distal end of the tube.

Monoclonal antibody MS-44B reacts with human dendritic, glial and endothelial cells: differential expression of MS-44B antigen by epidermal dendritic cells and by MS-1+ splenic sinusoidal endothelial cells. An immunohistological study

Rat monoclonal antibody MS-44B was raised against the dendritic human melanoma cell line SK-Mel 25 and detects highly dendritic cells and endothelial cells in various human organs. Among the cells recognized are dendritic cells in lymphoid organs, such as lymph node, tonsil and spleen, dendritic cells in skin, lung and lamina propria, (astro-)glial cells in the central nervous system and mesangial cells in the kidney. In peripheral lymph nodes (and less consistently in visceral lymph nodes), MS-44B reactive cells are found predominantly in the paracortical area and in the region of the marginal sinus; in tonsils these dendritic cells are concentrated at the outer rim of the follicle, while their distribution in the white pulp of the spleen is less well defined. In skin, both dermal and epidermal dendritic cells are stained. In the dermis just beneath the dermal-epidermal border, dendritic cells may be found with their processes protruding into the epidermal basal layer. MS-44B reactive epidermal dendritic cells send their processes in a horizontal direction or into the upper epidermal cell layers. MS-44B reactive epidermal dendritic cells are neither Langerhans cells, since they lack HLA-DR antigens and CD1, nor Merkel cells, since they lack cytokeratin expression. They rather seem to constitute a subpopulation of epidermal melanocytes that are low in tyrosinase expression and do not populate the melanocyte area of the hair bulb. With regard to the endothelium, monoclonal antibody MS-44B reveals marked heterogeneity in that it preferentially stains the endothelium of large and medium-sized arterial vessels, while capillary and venous endothelia are less well stained.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiodynamic effects of dopamine and dobutamine

On 11 patients undergoing coronary surgery, at the end of the surgical intervention, the inotropic responses to 0.4 and 0.8 microgram x kg-1 x min-1 dopamine and dobutamine given via the aorto-coronary bypass directly into the coronary artery were compared. These dosages correspond to ones 10 times greater applied intravenously. The measurements were made using needle force probes which were implanted into the myocardial offstream area in the left ventricular wall. Bypass flow was measured simultaneously by an electromagnetic flow probe. There is a significant increase in coronary bypass flow induced by both rates of 0.4 and 0.8 microgram x kg-1 x min-1 dobutamine, but there was no significant effect on bypass flow induced by dopamine. Developed myocardial force is raised more by dobutamine medication than by dopamine. However, the rate of contraction increases significantly and relaxation is significantly accelerated by dopamine at both dosages. A significant increase in rate of contraction and relaxation was only induced by the higher dosage of 0.8 microgram x kg-1 x min-1 dobutamine.

Quantitative assessment of the effects of 'inodilators' on the myocardium in patients without primary cardiac insufficiency after coronary surgery: Part II--Enoximone

Twelve patients undergoing routine coronary artery surgery received a bolus injection of 1.5 mg/kg enoximone between 8 and 18 hours and again between 18 and 48 hours after operation. No patient showed clinically manifest myocardial heart failure. The haemodynamic and cardiodynamic response to enoximone was quantified over a 30 minutes period following injection. Local myocardial developed force increased by 24 +/- 7% after the first and by 12 +/- 6% after the second injection. The rate of myocardial contraction increased by 50 +/- 14% and 15 +/- 10%, respectively, and relaxation increased by 35 +/- 14% and 22 +/- 19%. There was a decrease in total peripheral resistance of 38.8 and 42.9%, and an increase in heart rate of 11 and 15%. The mean arterial pressure showed small reductions from 73 (+/- 3.7) to 67 (+/- 2.6) mmHg for the first dose and from 83 (+/- 3.1) to 78.4 (+/- 2.8) mmHg for the second. Central venous and pulmonary artery pressures were essentially unaltered. The substantial positive inotropic effect of enoximone has been shown to match its peripheral vasodilatory activity, so that in the normovolaemic patient there is a clinically insignificant small fall in mean arterial pressure.

Quantitative assessment of the effects of 'inodilators' on the myocardium in patients without primary cardiac insufficiency after coronary surgery: Part I--Amrinone

The positive inotropic and peripheral vasodilating effect of amrinone has been measured in 20 patients without manifest cardiac insufficiency during the early (8-18 h postoperative) and late (18-48 h postoperative) recovery phase after coronary surgery. On conclusion of the surgical intervention first the aortocoronary bypass flow was compared during dobutamine and amrinone administration. It increased by 88% with amrinone and by 19% with dobutamine. Then a needle force probe was implanted in the myocardium. Directly measured local myocardial force increased not significantly by 3.5% after the first and by 5.1% after the second bolus injection of 2 mg/kg amrinone. The rate of myocardial contraction increased by 18.7% and 12%. The rate of relaxation decreased by 5.3% after the first and increased by 15% after the second injection. Mean pulmonary arterial pressure fell from 18.5 to 15.5 mmHg and from 19.7 to 17 mmHg. Cardiac output increased by 23% after the first and by 20% after the second injection. Heart rate rose from 88 to 99 bpm and from 86 to 94 bpm. Total peripheral resistance fell from 1,035 to 706 dyn*s*cm-5 and from 1,036 to 819 dyn*s*cm-5. The systolic arterial pressure fell from 132 to 116 mmHg after the first injection and did not change after the second injection. Amrinone was found to be a powerful peripheral vasodilator with a mild positive inotropic action. The variations in the effects between the early and late recovery phases mainly reflect a progressive haemodynamic stabilization with a decreasing tendency toward hypotensive disregulation. Careful consideration has to be paid to a properly balanced filling of the vascular system before administering amrinone.

[High-frequency ventilation: side effects and dangers]

Dangers of high-frequency ventilation result from the lack of a sensitive monitoring technique. Mucosal lesions of the trachea and the bronchi as well as cooling of the patient can be prevented by adequate humidification and heating of the gas flow. It is still controversial whether HFV leads to increased mucus production or secretolysis, and whether it prevents or promotes aspiration. The influence of mobilisation or immobilisation of a pulmonary focus on its recovery is not well understood. Interferences of HFV with the autonomic nervous system and endocrine system, like an increased release of PGI2, an antidiuretic and narcotic effect, with the coagulation system and the acid-base balance are inconsistent and therefore need particular clinical observation.

[High-frequency artificial respiration. II. Intratracheal high-frequency pressure changes with a rotation-valve catheter]

From the history of ventilatory support, the early studies of Auer und Meltzer only now seem to find a functional explanation. A rotating valve mounted on the tip of an endotracheal tube delivers a widespread gas bolus. The turbulent flow acts as a stirring device on the intrapulmonary gas volume. The method reduces the directional selectivity that typically limits the efficiency of jet ventilation. Systematically changing the rotational frequency between 10 and 80 Hz allows sequential stimulation, compartment by compartment, of the entire lung, which also gives rise to frequency-dependent local air-trapping that sequentially inflates different compartments. Jet ventilation and high-frequency oscillation were compared in dogs with the rotating valve tube by taking blood gas samples from 4-6 intrapulmonary veins: jet ventilation is characterized by preponderant ventilation of lung compartments opposite the lower aperture of the endotracheal tube. High-frequency oscillation induces a frequency dependent repartition of alveolar ventilation. The rotating valve tube definitely contributes to the homogenisation of alveolar ventilation in a manner that is less dependant upon segmental compliance than conventional ventilation.

The problem created by myocardial structure in assessing function

The clinical understanding of the dynamics of myocardial contraction is hampered by an over-simplified interpretation of the intramural pattern of force generation. This limits the anaesthetist's knowledge of the direct effects of commonly used anaesthetics. A discrimination between a negative inotropic effect and changes in pre- and afterload is usually impossible in clinical conditions. By using needle force probes, it is now possible to measure intramyocardial mesh tension in volumes as small as 3 mm3. Force mapping in 20 to 30 layers of the hearts of five normal dogs has shown that there are different patterns in the basal, middle and apical portions of the free wall of the left ventricle. An inhomogeneity is also observed when myocardial hypertrophy is produced by a 6-week period of aortic banding. However, this decreased the gradient in wall tension between the basal and the other portions of the ventricle. Inhomogeneities in wall tension increase the difficulty of assessing the contractile state of heart muscle. It may, however, be useful to compare local wall dynamics in the more isometrically-contracting basal segment with those in the middle portion which brings about most of the emptying of the ventricle. In the future, transoesophageal echocardiography may be used to measure variations in wall thickness which change the global loading conditions in the basal midwall compartments of the left ventricle.