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Biomedical subjects

G Marx

Publications and source records attributed to G Marx.

At least 19 recordsLinked to original sources
PubMed2000

Acute animal studies of the STARFlex system: a new self-centering cardioSEAL septal occluder.

The STARFlex system is a modified CardioSEAL device with a flexible self-centering mechanism comprised of nitinol springs strung between opposing arms, a connecting ball (sleeve joint that allows the device to pivot prerelease), and a front-loading delivery system. It was designed to allow a smaller device/defect sizing ratio and delivery profile, provide centering capability, and improve closure rates. To test this system, 13 devices (23, 28, and 33 mm) were deployed in six sheep within created atrial septal defects (12- to 22-mm diameter; n = 10), in the left atrium (n = 2), and in inferior vena cava (n = 1). All implantations in atrial septal defects were successful, with device/defect ratio ranging from 1.3 to 1.9 (median, 1.3), with no residual leak by angiography or echocardiography in seven (3/10 had </= small immediate leaks). The STARFlex system was effective in closing created atrial septal defects using a 10 Fr delivery sheath and low device/defect sizing ratios, comparing favorably with the standard CardioSEAL. Cathet. Cardiovasc. Intervent. 49:225-233, 2000.

Animals↗
PubMed2000

Colchicine-induced bone marrow suppression: treatment with granulocyte colony-stimulating factor.

Bone marrow aplasia is a frequent complication of colchicine poisoning. This typically occurs on day 3 to 5 postexposure, and the blood cell counts remain depressed for a week or more. Unfortunately, because patients suffering from colchicine toxicity develop multiple organ complications and sepsis, the morbidity and mortality associated with bone marrow depression is high. In this article, we present three cases of colchicine toxicity in which granulocyte colony-stimulating factor (G-CSF) was used to treat bone marrow depression. In all three cases, there was a dramatic increase in the white cell count and, to a lesser extent, the platelet count. In view of the critical nature of the bone marrow depression and multi-organ toxicity induced by colchicine, we believe that consideration of the use of G-CSF to shorten the duration of neutropenia is warranted.

Adolescent↗
PubMed2000

Low-dose dopexamine in patients undergoing hemihepatectomy: an evaluation of effects on reduction of hepatic dysfunction and ischaemic liver injury.

BACKGROUND: Hepatic dysfunction is a common problem in patients after hemihepatectomy. Treatment with low-dose dopamine has been shown to be beneficial in hemihepatectomy patients. We hypothesized that dopexamine, a synthetic vasoactive catecholamine, due to its specific pharmocodynamic profile may be more effective in reducing hidden ischaemic episodes in the hepato-splanchnic region during and after temporary total cross-clamping of hepatic inflow in these patients. METHODS: The effects of low-dose dopexamine on hepatic venous haemoglobin oxygen saturation (ShvO2), hepatic venous lactate level, monoethylglycinxylid (MEGX) formation, hepatic synthetic function and indicators for hepatic cell damage were studied during hemihepatectomy and for 16 h postoperatively in hemihepatectomy patients and compared to those of low-dose dopamine. In a prospective, double-blind clinical study 20 patients received randomly either dopexamine (DPX) 0.5 microg kg(-1) min(-1) (n=10) or dopamine (DO) 2.5 microg kg(-1) min(-1) (n= 10). Infusions were started after induction of anaesthesia and continued 16 h postoperatively. Hepatic vein, radial and pulmonary artery were catheterized. Measurements were carried out after induction of anaesthesia, after total cross-clamping of hepatic inflow, and at 2 h and 16 h postoperatively. RESULTS: There were no differences in systemic haemodynamics, oxygenation, ShvO2, serum aminotransferases or MEGX levels between the groups. At 16 h postoperatively prothrombin and antithrombin III levels were significantly lower while hepatic venous lactate was significantly higher in the DPX group compared to the DO group. CONCLUSION: In patients undergoing hemihepatectomy, we could not reveal superior hepatoprotective effects of low-dose dopexamine compared to low-dose dopamine.

Adult↗
PubMed2000

Haemodynamic, acid-base and electrolyte changes during plasma replacement with hydroxyethyl starch or crystalloid solution in young pigs.

We investigated haemodynamic, acid-base and electrolyte changes during almost total plasma replacement with hydroxyethyl starch (HES) and physiological balanced electrolyte solution (PBE) by using a cell saver in ten young pigs. In the PBE group an additional 3550 (444) ml crystalloid solution [Mean (SD)] was infused over the course of the study in order to maintain pulmonary capillary wedge pressure. Plasma protein levels decreased in both groups and the colloid osmotic pressure increased in HES and decreased in PBE. At the end of the study, body weight [HES 10.4 (1), PBE 13.1 (1.4) kg, P < 0.01] and lactic acid concentration [HES 0.9 (0.3), PBE 2.9 (1. 3) mmol.l -1, P < 0.01] was higher and tissue oxygen delivery [HES 327 (22), PBE 89 (29) ml.min.m2, P < 0.01] was lower in the PBE group. There were only moderate acid-base changes in both groups, but at the end, anion gap was significant lower in HES. In conclusion, maintenance of colloid osmotic pressure close to the physiological range of infants seems to be advantageous during major paediatric surgery.

Acid-Base Equilibrium↗
PubMed2000

Charcot-Marie-Tooth neuropathy type 2 and P0 point mutations: two novel amino acid substitutions (Asp61Gly; Tyr119Cys) and a possible "hotspot" on Thr124Met.

Mutations in the gene for the major protein component of peripheral nerve myelin, myelin protein zero (MPZ, P0), cause hereditary disorders of Schwann cell myelin such as Charcot-Marie-Tooth neuropathy type 1B (CMT1B), Dejerine-Sottas syndrome (DSS), and congenital hypomyelinating neuropathy (CHN). More recently, P0 mutations were identified in the axonal type of CMT neuropathy, CMT2, which is different from the demyelinating variants with respect to electroneurography and nerve pathology. We screened 49 patients with a clinical and histopathological diagnosis of CMT2 for mutations in the P0 gene. Three heterozygous single nucleotide changes were detected: two novel missense mutations, Asp61Gly and Tyr119Cys, and the known Thr124Met substitution, that has already been reported in several CMT patients from different European countries. Haplotype analysis for the P0 locus proved that our patients with the 124Met allele were not related to a cohort of patients with the same mutation, all of Belgian descent and all found to share a common ancestor. Our data suggest that P0 mutations account for a detectable proportion of CMT2 cases with virtually every patient harbouring a different mutation but recurrence of the Thr124Met amino acid substitution. The high frequency of this peculiar genotype in the European CMT population is presumably not only due to a founder effect but Thr124Met might constitute a mutation hotspot in the P0 gene as well.

Adult↗
PubMed1999

Three-dimensional echocardiographic analysis of valve anatomy as a determinant of mitral regurgitation after surgery for atrioventricular septal defects.

Mitral regurgitation (MR) is a significant complication after atrioventricular septal defect (AVSD) surgery. The relation of the valve leaflet morphology and the MR mechanism remains a conundrum. Two-dimensional echocardiography depicts leaflet edges, whereas volume-rendered 3-dimensional echocardiography provides direct visualization of the surface areas of the mitral valve leaflets. This study examines the relation of mitral valve anatomy as determined by 3-dimensional echocardiography with MR origins in patients after AVSD repair. Twenty-seven patients with AVSD surgery and Doppler color MR were prospectively enrolled (median age was 5 years and 16 patients had Down syndrome). Doppler color flow imaging of the MR jet and 3-dimensional echocardiography of the mitral valve were performed with a probe in the transthoracic or transesophageal position. Enface 3-dimensional views of the mitral valve from the left atrium were reconstructed. Analysis of the 3-dimensional data was possible in 21 of the 27 patients. Mean area ratios of the 3 mitral leaflets were calculated (superior 40 +/- 7%, inferior 35 +/- 5%, mural 25 +/- 6%). Both intra and interobserver variability on the area measurements were <5%. In 12 patients (group 1) the jet appeared to emanate medially from the region of coaptation of the superior and inferior components of the anterior leaflet. In 9 patients (group 2) the jet emanated more laterally from the region toward the mural leaflet. The area ratios of the inferior leaflet were 32 +/- 4% in group 1 and 38 +/- 6% in group 2 (p = 0.02). The area ratios of the mural leaflet were 28 +/- 5% in group 1 and 21 +/- 5% in group 2 (p = 0.007). The superior leaflet area ratio was not different in groups 1 and 2, 40 +/- 9% and 41 +/- 6%, respectively. Three-dimensional echocardiography provides new insight into the anatomic determinants of MR following AVSD surgery.

Adolescent↗
PubMed1999

[Circulatory function and oxygenation during hemihepatectomy. Dopamine versus dopexamine].

OBJECTIVE: The aim of this study was to compare low dose dopamine and dopexamine with respect to of liver-venous oxygen saturation, oxygen delivery and--demand, liver function tests and cardiocirculatory effects in the reperfusion period during a hemihepatectomy operation with occlusion of the liver hilus. METHODS: Twenty patients were studied in a randomised, doubleblind setting. They either received 2 micrograms/kg per min dopamine or 0.5 microgram/kg per min dopexamine perioperatively. For monitoring purposes a pulmonary artery and a liver venous catheter were placed. At four different time points hemodynamic parameter were assessed and blood samples were drawn. RESULTS: Significant changes between groups were found 5 min after opening the liver hilus for the cardiac index and the systemic oxygen delivery, as well as at the end of the operation for pulmonary shunt volume, which had increased more in the dopexamine group. No significant difference between liver venous oxygen saturation and liver function tests was found. CONCLUSION: Until more detailed studies concerning the influence of dopamine on the hepatic-splanchnic region during liver surgery are performed, dopexamine can not be considered superior to dopamine during these operations.

Dopamine↗
PubMed1999

Septic shock after liver transplantation for Caroli's disease: clinical improvement after treatment with C1-esterase inhibitor.

The extent of complement and contact activation is related to outcome in sepsis. A low functional index of their main blocker C1-esterase inhibitor (C1-INH) is considered as a relative deficiency of C1-INH and might contribute to the development of fatal complications in the intensive care unit. The first results of therapeutic intervention with C1-INH concentrate in septic shock are promising. We report on our experience of C1-INH concentrate administration in a young woman with Caroli's disease as ultimate rescue therapy for septic shock with capillary leakage syndrome after combined liver and kidney transplantation. No focus of infection was detectable and thus surgical intervention was not indicated. Antibiotic therapy at that time included vancomycin, tobramycin, meropenem and fluconazol. Hemodynamic stabilization occurred within hours after administration of C1-INH concentrate. Simultaneously a reduction in vasopressor medication was possible and negative fluid balance was achieved.

Adult↗
PubMed1999

Alteration of anion gap during almost total plasma replacement with synthetic colloids in piglets.

In ten piglets (body weight 8.2-11.6 kg), acid base, electrolyte and anion gap changes were investigated during almost total plasma replacement with hydroxyethyl starch (HES) and modified fluid gelatin (GEL) in saline solution using a cell saver autotransfusion technique. During the study, there were only moderate acid base changes, but marked disturbances in anion balance. At study end, the mean chloride concentration was significantly higher (mmol/l: normal values 97-108, HES 116 +/- 1.5, GEL 108 +/- 1.1, p < 0.01) and the mean anion gap was significantly lower in the HES group in comparison to the GEL group (mmol/l: normal values 5-14, HES 3 +/- 1.7, GEL 11.9 +/- 0.9, p < 0.01). It is concluded that plasma replacement with electroneutral HES, but not with negatively charged GEL, can lower the anion gap irrespective of the underlying disease. This can be misleading when the anion gap is used for differential diagnosis of metabolic acidosis in patients after large volume infusion of synthetic colloids.

Acid-Base Equilibrium↗
PubMed1999

Xenon inhalation increases airway pressure in ventilated patients.

BACKGROUND: The inert gas xenon, known as an anaesthetic for nearly 50 years, is also used as a contrast agent during computerised tomography (CT)-scanning. As xenon has a higher density and viscosity than air, xenon inhalation may increase airway resistance. METHODS: In a retrospective study we investigated the effects of 33% xenon/67% oxygen on airway pressure and cardio-respiratory parameters in 37 long-term mechanically ventilated patients undergoing cerebral blood flow (rCBF) measurements by means of stable xenon-enhanced CT. RESULTS: Xenon administration caused a significant increase in peak airway pressure from 31.6+/-8.0 cm H2O to 42.7+/-16.9 cm H2O. This effect was reproducible, did not occur after reduction of inspiratory flow rate by 50% from 0.56+/-0.15 L x s(-1) to 0.28+/-0.08 L x s(-1), and vanished immediately after termination of xenon delivery. CONCLUSION: Due to the higher density and viscosity of this gas mixture, ventilation with xenon/oxygen produces a higher Reynolds' number than oxygen/air when given at the same flow rate. This means that during xenon ventilation the zone of transition from turbulent to laminar gas flow may be located more peripherally (in smaller airways) than during oxygen/air ventilation with a subsequent increase in airway resistance. Our results indicate that xenon inhalation may cause a clinically relevant increase of peak airway pressure in mechanically ventilated patients.

Administration, Inhalation↗
PubMed1999

Fibrin microbeads (FMB) as biodegradable carriers for culturing cells and for accelerating wound healing.

We have developed biodegradable fibrin-derived microbeads as potent cell carriers. The fibrin-derived microbeads, 50-200 microm in diameter, were tested for their attachment to a wide range of cell types. Fibrin-derived microbeads were shown to be greatly haptotactic to cells (such as endothelial cells, smooth muscle cells and fibroblasts), which respond to fibrinogen in contrast to keratinocytes and different cell lines derived from leukocytic lineage. The cells on fibrin-derived microbeads could be maintained for more than 10 d and achieved a high density. 31P-nuclear magnetic resonance was employed to monitor phosphate metabolism in cells, with densities on the order of 100 million cells per g of fibrin-derived microbeads. The 31P-nuclear magnetic resonance adenosine triphosphate and phosphocreatine signals, equivalent to the signal obtained with perfused normal skin, indicated that metabolism of cells on fibrin-derived microbeads was responsive to oxygenation and nutrients. Light, fluorescent, and confocal laser microscopy revealed that the porous fibrin-derived microbeads accommodate up to 200-300 cells due to their high surface area which minimized contact inhibition. Cells could degrade the fibrin-derived microbeads and be transferred to seed culture flasks without trypsinization. In a pig skin wound healing model, fibrin-derived microbeads + fibroblasts were transplanted into full thickness punch wounds. This procedure was compared with other treatment modalities, such as the addition of human platelet-derived growth factor BB or fibrin-derived microbeads alone. By the third day after wounding, only the wounds in which fibroblasts on fibrin-derived microbeads were added showed significant formation of granulation tissue. Based on the above, we project many uses of our novel fibrin-derived microbead technology for cell culturing, wound healing and tissue engineering.

Animals↗
PubMed1999

[Behavior of piglets during castration with and without local anesthesia].

According to the German welfare act of 1998 (Art.5(3)1.), surgical castration of up to 4 wk old pigs does not require anaesthesia. However, the application of a local anaesthesia is discussed in the context of pain related responses to this procedure. In these experiments, effects of different methods of application on the behaviour of piglets during castration are evaluated as a contribution to the welfare assessment of this procedure. A total of 36 piglets between 10 and 14 days of age were castrated with and without a local anaesthesia. Local anaesthesia with Lidocaine 2% was applied in two ways: a) via intratesticular (i.t.) injection and b) intratesticular injection combined with subcutaneous (s.c.) infiltration of the anaesthetic into the tissue around the spermatic cord. The assessment of pain was performed on the basis of vocalisations and resistance movements of the animals during the procedure. Local anaesthesia resulted in a reduction of the relative proportion of resistance movements from the entire period of fixation (castration with i.t. anaesthesia 12.73%, with i.t. and s.c. anaesthesia 14.50% or without a local anaesthesia 18.96%; P < 0.05). In particular, local anaesthesia resulted in a reduction of resistance movements during the cutting of the spermatic cord. The response of piglets to additional skin stimulation of the scrotum was not different between the three treatments.

Anesthesia, Local↗
PubMed1998

Lower cancer risk in medium high radon.

Radon exposure was shown to be carcinogenic and suggested as a possible causative factor for lung cancer in man. A hypothesis is introduced that medium high radon (between 110 and 165 Bq/m3) causes lower cancer risk among women younger than 61 years, independent of the type of cancer. The presented results verify this statement with a probability of not less than 98%.

Adult↗
PubMed1998

Predictors of respiratory function deterioration after transfer of critically ill patients.

OBJECTIVES: Critically ill patients are often transferred due to the growing number of diagnostic procedures required to be performed outside the intensive care unit. These transfers have proved to be very critical. The aim of this study was to evaluate predictors for the deterioration of respiratory function in critically ill patients after transfer. DESIGN: Prospective, clinical, observational study. SETTING: 1800-bed university teaching hospital. SUBJECTS: 98 mechanically ventilated patients were investigated during transfer. MEASUREMENT AND MAIN RESULTS: Before transfer, all patients were classified according to the Acute Physiology and Chronic Health Evaluation (APACHE) II score and the Therapeutic Intervention Scoring System (TISS). Haemodynamics and arterial blood gases were measured at 11 different times. Arterial oxygen tension (PaO2), fractional inspired oxygen (FIO2), PaO2/FIO2 ratio, lowest PaO2/FIO2 ratio, minimal PaO2 and maximal FIO2, APACHE II score, TISS before transfer, age and duration of transfer were analysed as potential predictors for deterioration of respiratory function after transfer. Variables were analysed using Classification and Regression Trees and Clustering by Response. In 54 transports (55%) there was a decrease in the PaO2/FIO2 ratio, and a decrease of more than 20% from baseline was noted in 23 of the transferred patients (24%). Age > 43 years and FIO2 > 0.5 were identified as predictors for respiratory deterioration. CONCLUSIONS: Our predictors were able to indicate deterioration after transfer correctly in 20 of 22 patients (91%), combined with a false-positive rate in 17 of 49 (35%).

APACHE↗
PubMed1998

Haptotactic and growth stimulatory effects of fibrin(ogen) and thrombin on cultured fibroblasts.

We tested the ability of purified, ultraviolet C virally inactivated components of human fibrin sealant (FS) to modulate the chemotaxis, adherence, and proliferation of cultured cells. A fibrin clot formed on a near-confluent layer of human fibroblasts (HFs) recruited cells from the surrounding area. Thrombin (Thr) enhanced HF proliferation by a factor of 1.5 to 1.8, whereas fibrinogen (Fib) exerted only a minimal proliferative effect. We developed a new cell haptotactic/attachment assay by using Thr and Fib covalently bound to Sepharose beads (SBs). The kinetics of cell binding were approximately equivalent for beads coated with either protein. Uncoated SBs or fibrinogen-bound SBs (Fib-SB) pretreated with plasmin did not attract HFs. AlphaThr-SB induced a positive migratory response that was not affected by blocking its proteolytic site, whereas gammaThr-SB elicited no response. X irradiation of HFs at a dose of 6 Gy showed that the migratory response of HF is independent of proliferation, as confirmed by a bromodeoxyuridine uptake assay. Several types of cultured cells (murine fibroblasts, smooth muscle cells, aortic endothelial cells, and murine mammary carcinoma cells) also attached to Fib-SB. By contrast, human keratinocytes, human ovarian carcinoma cells, murine macrophage-like cells, leukemic cells, and murine mast cells did not attach. Our results provide some mechanistic insights into the haptotactic and proliferative effects of Fib and Thr on different cells.

Animals↗
PubMed1998

[Pulse oximetry and capnography in intensive care transportation: combined use reduces transportation risks].

OBJECTIVE: Due to the growing number of diagnostic and therapeutical procedures intensive-care patients must be transported intra- and interhospitally more often. These transports are among the most critical events during intensive-care therapy, with a high incidence of potentially life-threatening mishaps [23]. The aim of this study was to evaluate the possible benefit of the combined application of pulse oximetry and capnometry for patient safety during transport. METHODS: In a prospective clinical study 48 mechanically ventilated patients were allocated at random in 2 main study groups, 24 patients were investigated during interhospital transportation with an ambulance car, the other 24 patients during intrahospital transports. They were classified according to APACHE II and TISS. Blood pressure, heart rate and arterial blood gases were measured at eleven selected times. Twelve randomly chosen patients out of each main study group were monitored additionally with pulse oximetry and capnometry. The results were compared using the Mann-Whitney-U test. P < or = 0.05 was considered significant. RESULTS: Thirty-four patients had a TISS more than 40. The mean APACHE II-Score was 14 +/- 5. The overall incidence of potentially life-threatening mishaps was 9. Six out of these 9 occurred in the 24 patients with additional monitoring and were immediately detected by pulse oximetry or capnometry. CONCLUSIONS: The combination of pulse oximetry and capnometry offers the possibility to detect potentially life-threatening problems in ventilated patients during transport. This allows for early therapeutical consequences and may help to reduce the risk of transports.

APACHE↗