Effects of electro-mechanical uncouplers, hormonal stimulation and pacing rate on the stability and function of cultured rabbit myocardial slices

Introduction: Recent advances have enabled organotypic culture of beating human myocardial slices that are stable for weeks. However, human myocardial samples are rare, exhibit high variability and frequently originate from diseased hearts. Thus, there is a need to adapt long-term slice culture for animal myocardium. When applied to animal cardiac slices, studies in healthy or genetically modified myocardium will be possible. We present the culture of slices from rabbit hearts, which resemble the human heart in microstructure, electrophysiology and excitation-contraction coupling. Methods: Left ventricular myocardium from New Zealand White rabbits was cut using a vibratome and cultured in biomimetic chambers for up to 7 days (d). Electro-mechanical uncoupling agents 2,3-butanedione monoxime (BDM) and cytochalasin D (CytoD) were added during initiation of culture and effects on myocyte survival were quantified. We investigated pacing rates (0.5 Hz, 1 Hz, and 2 Hz) and hormonal supplements (cortisol, T3, catecholamines) at physiological plasma concentrations. T3 was buffered using BSA. Contractile force was recorded continuously. Glucose consumption and lactate production were measured. Whole-slice Ca2+ transients and action potentials were recorded. Effects of culture on microstructure were investigated with confocal microscopy and image analysis. Results: Protocols for human myocardial culture resulted in sustained contracture and myocyte death in rabbit slices within 24 h, which could be prevented by transient application of a combination of BDM and CytoD. Cortisol stabilized contraction amplitude and kinetics in culture. T3 and catecholaminergic stimulation did not further improve stability. T3 and higher pacing rates increased metabolic rate and lactate production. T3 stabilized the response to β-adrenergic stimulation over 7 d. Pacing rates above 1 Hz resulted in progredient decline in contraction force. Image analysis revealed no changes in volume fractions of cardiomyocytes or measures of fibrosis over 7 d. Ca2+ transient amplitudes and responsiveness to isoprenaline were comparable after 1 d and 7 d, while Ca2+ transient duration was prolonged after 7 d in culture. Conclusions: A workflow for rabbit myocardial culture has been established, preserving function for up to 7 d. This research underscores the importance of glucocorticoid signaling in maintaining tissue function and extending culture duration. Furthermore, BDM and CytoD appear to protect from tissue damage during the initiation phase of tissue culture.

Efficacy of Retreatment After Failed Direct-acting Antiviral Therapy in Patients With HCV Genotype 1-3 Infections

Hepatitis C virus infection is causing chronic liver disease, cirrhosis, and hepatocellular carcinoma. By combining direct-acting antivirals (DAAs), high sustained virologic response rates (SVRs) can be achieved. Resistance-associated substitutions (RASs) are commonly observed after DAA failure, and especially nonstructural protein 5A (NS5A) RASs may impact retreatment options.^1-3 Data on retreatment of DAA failure patients using first-generation DAAs are limited.^4-7 Recently, a second-generation protease- and NS5A-inhibitor plus sofosbuvir (voxilaprevir/velpatasvir/sofosbuvir [VOX/VEL/SOF]) was approved for retreatment after DAA failure.⁸ However, this and other second-generation regimens are not available in many resource-limited countries or are not reimbursed by regular insurance, and recommendations regarding the selection of retreatment regimens using first-generation DAAs are very important. This study aimed to analyze patients who were re-treated with first-generation DAAs after failure of a DAA combination therapy.

Remodeling of the transverse tubular system after myocardial infarction in rabbit correlates with local fibrosis: A potential role of biomechanics

The transverse tubular system (t-system) of ventricular cardiomyocytes is essential for efficient excitation-contraction coupling. In cardiac diseases, such as heart failure, remodeling of the t-system contributes to reduced cardiac contractility. However, mechanisms of t-system remodeling are incompletely understood. Prior studies suggested an association with altered cardiac biomechanics and gene expression in disease. Since fibrosis may alter tissue biomechanics, we investigated the local microscopic association of t-system remodeling with fibrosis in a rabbit model of myocardial infarction (MI). Biopsies were taken from the MI border zone of 6 infarcted hearts and from 6 control hearts. Using confocal microscopy and automated image analysis, we quantified t-system integrity (I_TT) and the local fraction of extracellular matrix (f_ECM). In control, f_ECM was 18 ± 0.3%. I_TT was high and homogeneous (0.07 ± 0.006), and did not correlate with f_ECM (R² = 0.05 ± 0.02). The MI border zone exhibited increased f_ECM within 3 mm from the infarct scar (30 ± 3.5%, p < 0.01 vs control), indicating fibrosis. Myocytes in the MI border zone exhibited significant t-system remodeling, with dilated, sheet-like components, resulting in low I_TT (0.03 ± 0.008, p < 0.001 vs control). While both f_ECM and t-system remodeling decreased with infarct distance, I_TT correlated better with decreasing f_ECM (R² = 0.44) than with infarct distance (R² = 0.24, p < 0.05). Our results show that t-system remodeling in the rabbit MI border zone resembles a phenotype previously described in human heart failure. T-system remodeling correlated with the amount of local fibrosis, which is known to stiffen cardiac tissue, but was not found in regions without fibrosis. Thus, locally altered tissue mechanics may contribute to t-system remodeling.

Identification of the putative binding pocket of valerenic acid on GABAA receptors using docking studies and site-directed mutagenesis

Background and Purpose

β2/3‐subunit‐selective modulation of GABA_A receptors by valerenic acid (VA) is determined by the presence of transmembrane residue β2/3N265. Currently, it is not known whether β2/3N265 is part of VA's binding pocket or is involved in the transduction pathway of VA's action. The aim of this study was to clarify the localization of VA's binding pocket on GABA_A receptors.

Experimental Approach

Docking and a structure‐based three‐dimensional pharmacophore were employed to identify candidate amino acid residues that are likely to interact with VA. Selected amino acid residues were mutated, and VA‐induced modulation of the resulting GABA_A receptors expressed in Xenopus oocytes was analysed.

Key Results

A binding pocket for VA at the β⁺/α⁻ interface encompassing amino acid β3N265 was predicted. Mutational analysis of suggested amino acid residues revealed a complete loss of VA's activity on β3M286W channels as well as significantly decreased efficacy and potency of VA on β3N265S and β3F289S receptors. In addition, reduced efficacy of VA‐induced I_GABA enhancement was also observed for α1M235W, β3R269A and β3M286A constructs.

Conclusions and Implications

Our data suggest that amino acid residues β3N265, β3F289, β3M286, β3R269 in the β3 subunit, at or near the etomidate/propofol binding site(s), form part of a VA binding pocket. The identification of the binding pocket for VA is essential for elucidating its pharmacological effects and might also help to develop new selective GABA_A receptor ligands.

Analyzing Remodeling of Cardiac Tissue: A Comprehensive Approach Based on Confocal Microscopy and 3D Reconstructions

Microstructural characterization of cardiac tissue and its remodeling in disease is a crucial step in many basic research projects. We present a comprehensive approach for three-dimensional characterization of cardiac tissue at the submicrometer scale. We developed a compression-free mounting method as well as labeling and imaging protocols that facilitate acquisition of three-dimensional image stacks with scanning confocal microscopy. We evaluated the approach with normal and infarcted ventricular tissue. We used the acquired image stacks for segmentation, quantitative analysis and visualization of important tissue components. In contrast to conventional mounting, compression-free mounting preserved cell shapes, capillary lumens and extracellular laminas. Furthermore, the new approach and imaging protocols resulted in high signal-to-noise ratios at depths up to 60 µm. This allowed extensive analyzes revealing major differences in volume fractions and distribution of cardiomyocytes, blood vessels, fibroblasts, myofibroblasts and extracellular space in control vs. infarct border zone. Our results show that the developed approach yields comprehensive data on microstructure of cardiac tissue and its remodeling in disease. In contrast to other approaches, it allows quantitative assessment of all major tissue components. Furthermore, we suggest that the approach will provide important data for physiological models of cardiac tissue at the submicrometer scale.

Effects of metoprolol therapy on cardiac gap junction remodelling and conduction in human chronic atrial fibrillation

BACKGROUND AND PURPOSE

We investigated the influence of metoprolol on gap junction proteins connexin43 (Cx43) and connexin40 (Cx40) in atrial tissue from patients with/without atrial fibrillation (AF).

EXPERIMENTAL APPROACH

Left atrial tissue samples from 160 patients with AF or sinus rhythm (SR) with or without metoprolol (mean daily dose: 65.2 ± 9.1 mg·day⁻¹) were analysed for Cx43 and Cx40 by Western blot and immunohistology. Transverse and longitudinal conduction velocities were determined by 64 multi-electrode mapping.

KEY RESULTS

Both Cx43 and Cx40 expression were significantly increased in patients with AF versus SR. Cx43-expression in AF was significantly higher in patients receiving metoprolol, while Cx40 expression was unaffected by metoprolol treatment. In AF, the ratio of lateral/polar expression of Cx43 and Cx40 was enhanced due to increased expression at the sides of the cells (lateral) and a loss at the cell poles. This AF-induced increase in lateral/polar expression of Cx43, but not of Cx40, was significantly antagonized by metoprolol treatment. Functionally, in AF patients, transverse conduction velocity in atrial samples was significantly enhanced and this change was also significantly antagonized by metoprolol.

CONCLUSIONS AND IMPLICATIONS

AF induced enhanced lateral expression of Cx43 and Cx40 together with enhanced transverse conduction velocity in left atrial tissue. Alterations in localization of Cx43 and conduction changes were both antagonized by metoprolol, showing that pharmacological modulation of gap junction remodelling seems, in principle, possible. This finding may open new approaches to the development of anti-arrythmic drugs.

Age related changes in mitochondrial function and new approaches to study redox regulation in mammalian oocytes in response to age or maturation conditions

Mammalian oocytes are long-lived cells in the human body. They initiate meiosis already in the embryonic ovary, arrest meiotically for long periods in dictyate stage, and resume meiosis only after extensive growth and a surge of luteinizing hormone which mediates signaling events that overcome meiotic arrest. Few mitochondria are initially present in the primordial germ cells while there are mitogenesis and structural and functional differentiation and stage-specific formation of functionally diverse domains of mitochondria during oogenesis. Mitochondria are most prominent cell organelles in oocytes and their activities appear essential for normal spindle formation and chromosome segregation, and they are one of the most important maternal contributions to early embryogenesis. Dysfunctional mitochondria are discussed as major factor in predisposition to chromosomal nondisjunction during first and second meiotic division and mitotic errors in embryos, and in reduced quality and developmental potential of aged oocytes and embryos. Several lines of evidence suggest that damage by oxidative stress/reactive oxygen species in dependence of age, altered antioxidative defence and/or altered environment and bi-directional signaling between oocyte and the somatic cells in the follicle contribute to reduced quality of oocytes and blocked or aberrant development of embryos after fertilization. The review provides an overview of mitogenesis during oogenesis and some recent data on oxidative defence systems in mammalian oocytes, and on age-related changes as well as novel approaches to study redox regulation in mitochondria and ooplasm. The latter may provide new insights into age-, environment- and cryopreservation-induced stress and mitochondrial dysfunction in oocytes and embryos.

MCAK is present at centromeres, midspindle and chiasmata and involved in silencing of the spindle assembly checkpoint in mammalian oocytes

Mitotic centromere-associated kinesin (MCAK) is an ATP-dependent microtubule (MT) depolymerase regulated by Aurora kinase (AURK) phosphorylation and implicated in resolution of improper MT attachments in mitosis. Distribution of MCAK was studied in oocyte maturation by anti-MCAK antibody, anti-tubulin antibody, anti-AURKB antibody and anti-centromere antibody (ACA) and by the expression of MCAK-enhanced green fluorescent protein fusion protein in maturing mouse oocytes. Function was assessed by knockdown of MCAK and Mad2, by inhibiting AURK or the proteasome, by live imaging with polarization microscope and by chromosomal analysis. The results show that MCAK is transiently recruited to the nucleus and transits to spindle poles, ACA-positive domains and chiasmata at prometaphase I. At metaphase I and II, it is present at centrosomes and centromeres next to AURKB and checkpoint proteins Mad2 and BubR1. It is retained at centromeres at telophase I and also at the midbody. Knockdown of MCAK causes a delay in chromosome congression but does not prevent bipolar spindle assembly. MCAK knockdown also induces a meiosis I arrest, which is overcome by knockdown of Mad2 resulting in chiasma resolution, chromosome separation, formation of aberrant meiosis II spindles and increased hypoploidy. In conclusion, MCAK appears to possess a unique distribution and function in oocyte maturation. It is required for meiotic progression from meiosis I to meiosis II associated with silencing of the spindle assembly checkpoint. Alterations in abundance and activity of MCAK, as implicated in aged oocytes, may therefore contribute to the loss of control of cell cycle and chromosome behaviour, thus increasing risk for errors in chromosome segregation and aneuploidy.

Treatment during primary HIV infection does not lower viral set point but improves CD4 lymphocytes in an observational cohort

Objective

To investigate if early treatment of primary HIV-1 infection (PHI) reduces viral set point and/or increases CD4 lymphocytes.

Methods

Analysis of two prospective multi-centre PHI cohorts. HIV-1 RNA and CD4 lymphocytes in patients with transient treatment were compared to those in untreated patients. Time to CD4 lymphocyte decrease below 350/μl after treatment stop or seroconversion was calculated using Kaplan-Meier and Cox-PH-regression analyses.

Results

156 cases of PHI were included, of which 100 had received transient HAART (median treatment time 9.5 months) and 56 remained untreated. Median viral load (563000 cop/ml vs 240000 cop/ml; p < 0.001) and median CD4 lymphocyte (449/μl vs. 613/μl; p < 0.01) differed significantly between treated and untreated patients. Median viral load was 38056 copies/ml in treated patients (12 months after treatment stop) and 52880 copies/ml in untreated patients (12 months after seroconversion; ns). Median CD4 lymphocyte change was +60/μl vs. -86/μl (p = 0.01). Median time until CD4 lymphocytes decreased to < 350/μl (including all patients with CD4 lymphocytes < 500/μl during seroconversion) was 20.7 months in treated patients after treatment stop and 8.3 months in untreated patents after seroconversion (p < 0.01). Cox-PH analyses adjusting for baseline VL, CD4 lymphocytes, stage of early infection and symptoms confirmed these differences.

Conclusions

Treatment during PHI did not lower viral set point. However, patients treated during seroconversion had an increase in CD4 lymphocytes, whereas untreated patients experienced a decrease in CD4 lymphocytes. Time until reaching CD4 lymphocytes < 350/μl was significantly shorter in untreated than in treated patients including patients with CD4 lymphocytes < 500/μl during seroconversion.

[Occupational and non-occupational risk factors in bladder cancer patients in an industrialized area located in former East-Germany]

PURPOSE

Several occupational carcinogens are metabolized by polymorphic enzymes. The distribution of the polymorphic enzymes N-acetyltransferase 2 (NAT2; substrates: aromatic amines), glutathione S-transferase M1 (GSTM1; substrates: e. g., reactive metabolites of polycyclic aromatic hydrocarbons), and glutathione S-transferase T1 (GSTT1; substrates: small molecules with 1 - 2 carbon atoms) were investigated.

MATERIAL AND METHODS

At the urological department in Lutherstadt Wittenberg, 136 patients with a histologically proven transitional cell cancer of the urinary bladder were investigated for all occupations performed for more than 6 months. Several occupational and non-occupational risk factors were asked. The genotypes of NAT2, GSTM1, and GSTT1 were determined from leucocyte DNA by PCR.

RESULTS

Compared to the general population in Middle Europe, the percentage of GSTT1 negative persons (22.1 %) was ordinary; the percentage of slow acetylators (59.6 %) was in the upper normal range, while the percentage of GSTM1 negative persons (58.8 %) was elevated in the entire group. Shifts in the distribution of the genotypes were observed in subgroups who had been exposed to asbestos (6/6 GSTM1 negative, 5/6 slow acetylators), rubber manufacturing (8/10 GSTM1 negative), and chlorinated solvents (9/15 GSTM1 negative).

CONCLUSIONS

The overrepresentation of GSTM1 negative bladder cancer patients also in this industrialized area and more pronounced in several occupationally exposed subgroups points to an impact of the GSTM1 negative genotype in bladder carcinogenesis.

Ambulatory electrogastrography in patients with sclerodermia, delayed gastric emptying, dyspepsia, and irritable bowel syndrome. Is there any clinical relevance?

Background: Changes in electrogastrographic parameters are described in patients with irritable bowel syndrome, sclerodermia, dyspepsia, and delayed gastric emptying in static measurements. However, no information is available about changes in ambulatory measurements. The objective of this study was to find parameters that discriminate between these diseases using cutaneous 24-h-electrogastrography. Methods: Cutaneous 24-h electrogastrography (EGG) measurements were taken from 20 patients with dyspepsia, 10 patients with systemic sclerosis (sclerodermia, SSc), 7 patients with irritable bowel syndrome (IBS), 7 patients with delayed gastric emptying, and 10 healthy volunteers. Measurements were made using a DIGITRAPPER EGG (Synectics Medical Inc., Stockholm, Sweden) and the accompanying computerized data analysis package (ElectroGastroGram Version 6.30, Gastrosoft Inc., Synectics Medical Inc., Stockholm, Sweden). Frequency and power were compared pre- and postprandially, as well as during the entire day of measurement. Results: The 24-h measurements in healthy volunteers revealed 45.00%+/-12.12% normal values (2.4-3.7 cpm), 30.10%+/-7.15% bradygastric values (<2.4 cpm), and 24.20%+/-7.76% tachygastric values (>3.7 cpm). There was no significant change in frequency between rest and motion, but there was a significant increase in power (P<0.05). There was significantly more bradygastria in patients with dyspepsia periprandially as well as after 24 h (P<0.01) than in healthy volunteers. The mean power of patients with dyspepsia was significantly higher than that of patients with IBS (P<0.05). Conclusion: Cutaneous 24-h-EGG may be used as an additional means of differentiating between dyspepsia and IBS.

Tropheryma whippelii DNA in saliva of patients without Whipple's disease

Tropheryma whippelii is the causative agent of Whipple's disease, a difficult to diagnose systemic illness. Amplification of part of its 16S ribosomal RNA gene(s) has become a standard diagnostic method because of increased sensitivity as compared to classical histopathological analysis. Recently, we demonstrated the presence of T. whippelii DNA by PCR in duodenal biopsies and/or gastric juice of a considerable fraction of individuals without clinical signs of Whipple's disease. In this follow-up study, saliva and dental plaques of the same patients were screened for the presence of T. whippelii DNA. Six out of the 14 previously PCR-positive persons but none of the 17 controls had T. whippelii DNA in their saliva. Our results suggest that Whipple bacteria are ubiquitous environmental or commensal organisms causing Whipple's disease only in a particular subset of individuals, possibly those with an as yet uncharacterized immunological defect.

[Treatment of scoliosis and scoliokyphosis in Recklinghausen neurofibromatosis]

Spine deformities are a frequent symptom of neurofibromatosis Recklinghausen. Especially NF1 shows next to numerous alterations in the skeleton in some cases massive scoliosis and kyphosis. There are different theories for the development of the spine deformities, one of them is that specific alterations of the vertebra are caused by an elevated intraspinal pressure on the osteoporotic bone. A classification from a clinical point of view discriminates 3 types of severity. Type 1 shows instead of the in x-rays inconspicuous findings neurofibromatosistypical alterations in other diagnostic procedures (e.g. MRI). Extreme variations like short curved scoliokyphosis with massive destruction and severe spine imbalance are described as type 3. Operative treatment is dependent on the severity of the deformity. Intraspinal tumors have to be removed. Because of the elevated neurological risk the proceeding has to be very careful, sometimes there is a temporary Halo-extension necessary. Anterior substance defects are filled with bone or cages. The posterior instrumentation (in most of the cases a 2-rod-stabilization) is performed by transpedicular screws. Frequently there is a concave chest wall plastic (CTP) indicated. To prevent neurological complications early surgical procedure is sometimes necessary. Complications can be reduced by careful proceeding, exact preoperative diagnostic and classification. But next to operative experience a qualified anaesthesiological and intensive care units are absolutely necessary.

[Efficacy of ultrasound controlled direct reposition of fragments of the posterior vertebral body facet]

To calculate canal compromise and decrease of midsagittal diameter caused by retropulsion of fragments into the spinal canal we analyzed the pre- and postoperative computed tomographies of 32 patients with unstable thoracolumbar burst fractures treated by USS (universal spine system). Our intention was to examine the efficiency of ultrasound guided repositioning of the dispaced fragments which was performed in all 32 cases. We found a clear postoperative enlargement of canal area (ASP preoperatively 55%, postop. 80%) and midsagittal diameter (MSD preop. 58%, postop. 78%). 10 of 13 patients presented a postoperative improvement of neurological deficit, no neurological deterioration occurred. Fractures with neurological deficit showed more canal compromise (52%) and less midsagittal diameter (MSD compromise 51%) than those without (40% or 39%). There was no correlation between the percentage of spinal canal stenosis and the severity of neurological deficit. Below L 1 the spinal canal is greater than between Th 11 and L 1, so a more important spinal stenosis is tolerated. In case of unstable burst fractures with neurological deficit the ultrasound guided spinal fracture reposition is an effective procedure concerning the necessary improvement of spinal stenosis: an additional ventral approach for the revision of the spinal canal is unneeded. In fractures without neurologic deficit the repositioning of the displaced fragments promises an avoidance of long-term damages such as myelopathia and claudicatio spinalis.

[Paradoxical embolism after femoral fracture]

The foramen ovale is anatomically open in 25% of individuals, but functionally closed by the higher pressure in the left antrum. Right-to-left shunt and subsequent paradoxical embolism may occur when pressure in the left antrum rises, for example, as a result of pulmonary embolism. In the present case we demonstrate a patient who presented 20 days after osteosynthetic treatment of a femoral fracture with word-finding deficits. Cerebral MRT revealed a fresh ischemic insult. Duplex ultrasound of the legs showed a fresh thrombosis of the superficial femoral vein and scintigraphy of the lungs detected pulmonary embolism. Transesophageal contrast echocardiography trapped a hemodynamically spontaneous, open foramen ovale. Duplex ultrasound of the carotid arteries detected no pathological findings. Deep vein thrombosis and pulmonary embolism can be clinically inconspicuous and become manifest by cerebral deficits resulting from paradox embolism and cerebral ischemia.

[Magnetic resonance tomography examination of thoracolumbar spinal fractures after fixateur interne stabilization]

To analyse the possible injuries of vertebral segments, especially the disc, after unstable thoracolumbar fractures stabilised with AO internal fixator, we performed magnetic resonance imaging (MRI) of the traumatised region after implant removal. There were two aspects of disc degeneration (DD):(1) biochemical changes and (2) structural damage. MRI detects biochemical processes as one aspect of DD that is often small even in the presence of greater structural damage of the nucleus pulposus caused by fracture. None of the patients presented with structural failure of the anulus fibrosus, which is the essential structural component of the vertebral segments with regard to stability. We observed biochemical changes more often in the lower of the two fracture-adjacent discs and alterations of discal shape more often in the upper of the two, whereas loss of height concerned both discs to approximately the same degree. The supporters of upper-disc resection in thoracolumbar fractures justify their procedure among other things with the structural disc damage, such as alteration of shape and loss of height (altogether more frequent in the upper disc). Our observations that a disc with a structurally altered nucleus pulposus can be biochemically intact and can show an intact anulus fibrosus are arguments in favour of disc preservation. With regard to the upper disc, the widespread opinion that complete and regular disc damage requires a resection has to be revised. The question of whether the lower disc should be resected more often because of its greater biochemical changes cannot be answered by the present study alone. Besides the excellent static information in all anatomical structures of the vertebral column available by MRI, a repeat examination in a prone position yields dynamic information on the spinal cord in the case of suspected dorsal adhesions.

[Paget's disease of the proximal ulna--a rare monostotic manifestation]

Bone changes of the upper extremity are rare manifestations of the M. Paget disease. Most frequently the disease affects the lower extremities, the pelvis followed by the calvarium and others. The rare asymptomatic, monostotic manifestation of Paget's disease of the left proximal ulnae of a 59 year old woman and the way of diagnosis is described. Symptomatic skeletal lesions are detected by radiological examination, bone scintigraphy reveals asymptomatic lesions. Laboratory tests (Alkaline serum phosphatase, Hydroxyproline in urine) monitor the activity of the disease.

Familial predisposition for degenerative disc disease. A case-control study

STUDY DESIGN

This case-control study was undertaken to determine if relatives of patients who had been admitted for surgery for degenerative disc disease-related problems were at increased risk for lower back pain or sciatica.

OBJECTIVES

To determine if familial factors play a role in placing a person at risk for development of degenerative disc disease of the lumbar spine.

SUMMARY OF BACKGROUND DATA

It is known that smoking and various occupational factors can place a person at risk for degenerative disc disease problems. It is not known if a familial predisposition may also exist.

METHODS

The family members and relatives of 65 patients who had undergone surgery for lumbar degenerative disc disease were interviewed with a standardized questionnaire and compared with a control group of 67 patients who had been admitted to hospital for non-spine-related orthopedic procedures. The same interview and standardized questionnaire was used for both groups by a single observer.

RESULTS

In the study group of 65 patients who had undergone surgery for degenerative disc disease, 44.6% were noted to have a positive family history, whereas 25.4% of the patients in the control group had a positive family history. Eighteen and one-half percent of relatives in the study group had a history of having spinal surgery, compared with only 4.5% of the control group.

CONCLUSIONS

The results indicate that a familial predisposition to degenerative disc disease can exist along with other risk factors.

Platelet aggregation inhibiting and anticoagulant effects of oligoamines, XXVIII: Oligoamines with fluorescent properties. Part C: Fluorescent oligoamines with enhanced hydrophilic properties

Fifteen fluorescent oligoamines with one or two fluorescent groups and two or three basic N-functions were prepared and tested for antiplatelet activity (Born-test). Five compounds involving three different fluorophores, i.e. 2-fluorenyl, 1-pyrenyl, and 9-phenanthryl, show an IC50 of 7-11 mumol/L. They are suitable to serve as probes in the field of oligoamine-biopolymere interactions.

[Biomechanical prerequisites for examining the stability of osteosynthesis procedures of the spine]

Basic reflections on biomechanical tests of spinal implants are reviewed. Four different pedicle screw systems are compared during loading in extension, flexion, side-bending, and rotation. The thoracolumbar and the lumbar spine were tested. Stability against rotation forces was lowest in all systems. Because of this, a cross-connector is recommended in highly unstable situations. All tests were done in cadaver spines with normal bone mineral density (measured before the tests). The first series of tests was done without destroying the cadavers. A second series was done with maximal load until the implants or the bony bed of the screws failed. The results show that rigid implants more often led to pedicle fractures. An unstable screw rod interface led to implant failure. Cadaver tests can provide answers about the primary stability characteristic only. Fatigue tests are not possible in cadaver spines because they become autolytic before enough cycles can be applied.

Platelet aggregation inhibiting and anticoagulant effects of oligoamines, XVIII: Oligoamines with fluorescent properties, Part B: Fluorophores in the molecular periphery

Seventeen N,N'-benzene-1,3-dimethane and nine N,N',N''-benzene-1,3,5-trimethane derivatives with fluorescent properties have been synthesized. Three of them show antiplatelet activities (inducer collagen, IC50 Born-test) in concentrations < 10 mumol/L. They are suitable for interaction studies with biological macromolecules and synthetical and biological membranes. Structure activity relationships demonstrate that heteropolycyclic fluorophores i.e. quinoline, dibenzofurane, or carbazole are favorable substituents for this purpose.

[Stability of pedicle screws. 1: Maximum pullout force in healthy bony spine trunks with reference to drilling technique]

Pullout direction was axial and oblique to screw axis. Two different techniques of preparing the screw bed are matched: 1) 3.2 mm AO drill and 6.0 mm screws for D7-S1 and 4.5 mm screws for D11-D6, 2) resection of cancellous bone of the pedicle tube and 6.0 mm, 7.0 mm, 8.0 mm screws, which were inserted after measuring each level. With the better technique 1 (saving the cancellous bone) 620N-161N were reached from D1-S1, even if bigger screws could be used with technique 2.

Pulmonary microvascular fat: the significance?

OBJECTIVE

To determine the effects of fat emboli on cardiopulmonary function in critically ill patients.

DESIGN

A prospective study.

SETTING

Tertiary referral medical/surgical shock/trauma intensive care unit (ICU).

PATIENTS

A total of 51 critically ill medical and surgical (including acute trauma) patients who required supplemental oxygen (FIO2 of > or = 0.35) to maintain arterial blood oxyhemoglobin saturation of > or = 90% and who had 62 pulmonary artery catheters placed for patient care reasons.

INTERVENTIONS

Pulmonary capillary blood samples were obtained via the pulmonary artery catheters in the "wedged position" at insertion and postinsertion at 8, 24, 48, and 72 hrs. Cytospun smears of the buffy coat aspirates of these samples were made and were stained with Oil Red-O for fat.

MEASUREMENTS AND MAIN RESULTS

One investigator, without knowledge of the patients' cardiopulmonary function, examined all smears and graded them 0 to 4+ for amount of fat. Fat scores were correlated with chest radiograph appearance, hemodynamic and respiratory parameters, complete blood cell counts with differential white blood cell counts, whether the patient was receiving lipid-containing parenteral nutrition, principal organ system failure, and reason for ICU admission. Samples from 27 pulmonary artery catheter insertions had no fat, 13 samples had low-grade (1+) episodic fat, and 22 samples had repeated episodes of > or = 2+ fat or isolated episodes of 4+ fat. There was a significant association between the amount of pulmonary microvascular fat and trauma as the reason for ICU admission. Of the other parameters, only chest compliance and body temperature showed unequivocal significant associations. These associations were opposite to the expected findings, but would support a conclusion that fat emboli did not cause the observed cardiopulmonary dysfunction. The inconsistent associations for the FIO2, PCO2, and mixed venous blood oxyhemoglobin saturation may be random events.

CONCLUSION

Cardiopulmonary dysfunction commonly attributed to fat emboli is likely due to other causes.

Platelet aggregation inhibiting and anticoagulant effects of oligoamines, XVII: Oligoamines with fluorescent properties. Part A: Fluorescent bridged nitrogen functions

Eleven dimethanamines and one disydnonimine with fluorescent properties have been synthesized. All of them show antiplatelet activities (IC50, Born-test) in concentrations between 14-75 mumol/L. Five of them inhibited fibrin formation induced by thromboplastin by more than 75% in a 200 mu molar concentration. Both effect do not run parallel. The most space consuming fluorophores show the smallest inhibition of the platelet aggregation. Best results were obtained with an azulene, acenaphthene or naphthalene moiety between the two basic nitrogen functions.