Access Planning and Resource Coordination for Clinical Research Operations

This research creates an operations engineering and management methodology to optimize a complex operational planning and coordination challenge faced by sites that perform clinical research trials. The time-sensitive and resource-specific treatment sequences for each of the many trial protocols conducted at a site make it very difficult to capture the dynamics of this unusually complex system. Existing approaches for site planning and participant scheduling exhibit both excessively long and highly variable Time to First Available Visit (TFAV) waiting times and high staff overtime costs. We have created a new method, termed CApacity Planning Tool And INformatics (CAPTAIN) that provides decision support to identify the most valuable set of research trials to conduct within available resources and a plan for how to book their participants. Constraints include (i) the staff overtime costs, and/or (ii) the TFAV by trial. To estimate the site's metrics via a Mixed Integer Program, CAPTAIN combines a participant trajectory forecasting with an efficient visit booking reservation plan to allocate the date for the first visit of every participant's treatment sequence. It also plans a daily nursing staff schedule that is optimized together with the booking reservation plan to optimize each nurse's shift assignments in consideration of participants' requirements/needs.

A new method to evaluate temperature vs. pH activity profiles for biotechnological relevant enzymes

BACKGROUND

Glycoside hydrolases are important for various industrial and scientific applications. Determination of their temperature as well as pH optima and range is crucial to evaluate whether an enzyme is suitable for application in a biotechnological process. These basic characteristics of enzymes are generally determined by two separate measurements. However, these lead to a two-dimensional assessment of the pH range at one temperature (and vice versa) and do not allow prediction of the relative enzymatic performance at any pH/temperature combination of interest. In this work, we demonstrate a new method that is based on experimental data and visualizes the relationship among pH, temperature, and activity at a glance in a three-dimensional contour plot.

RESULTS

In this study, we present a method to determine the relative activity of an enzyme at 96 different combinations of pH and temperature in parallel. For this purpose, we used a gradient PCR cycler and a citrate-phosphate-based buffer system in microtiter plates. The approach was successfully tested with various substrates and diverse assays for glycoside hydrolases. Furthermore, its applicability was demonstrated for single enzymes using the endoglucanase Cel8A from Clostridium thermocellum as well as the commercially available complex enzyme mixture Celluclast^®. Thereby, we developed a fast and adaptable method to determine simultaneously both pH and temperature ranges of enzymes over a wide range of conditions, an easy transformation of the experimental data into a contour plot for visualization, and the necessary controls. With our method, the suitability of an enzyme or enzyme mixture for any chosen combination of temperature and pH can easily be assessed at a glance.

CONCLUSIONS

We propose a method that offers significant advantages over commonly used methods to determine the pH and temperature ranges of enzymes. The overall relationship among pH, temperature, and activity is visualized. Our method could be applied to evaluate exactly what conditions have to be met for optimal utilization of an enzyme or enzyme mixture for both lab-scale and industrial processes. Adaptation to other enzymes, including proteases, should be possible and the method may also lead to a platform for additional applications, such as inactivation kinetics analysis.

Characterization of the arabinoxylan-degrading machinery of the thermophilic bacterium Herbinix hemicellulosilytica-Six new xylanases, three arabinofuranosidases and one xylosidase

Herbinix hemicellulosilytica is a newly isolated, gram-positive, anaerobic bacterium with extensive hemicellulose-degrading capabilities obtained from a thermophilic biogas reactor. In order to exploit its potential as a source for new industrial arabinoxylan-degrading enzymes, six new thermophilic xylanases, four from glycoside hydrolase family 10 (GH10) and two from GH11, three arabinofuranosidases (1x GH43, 2x GH51) and one β-xylosidase (GH43) were selected. The recombinantly produced enzymes were purified and characterized. All enzymes were active on different xylan-based polysaccharides and most of them showed temperature-vs-activity profiles with maxima around 55-65°C. HPAEC-PAD analysis of the hydrolysates of wheat arabinoxylan and of various purified xylooligosaccharides (XOS) and arabinoxylooligosaccharides (AXOS) was used to investigate their substrate and product specificities: among the GH10 xylanases, XynB showed a different product pattern when hydrolysing AXOS compared to XynA, XynC, and XynD. None of the GH11 xylanases was able to degrade any of the tested AXOS. All three arabinofuranosidases, ArfA, ArfB and ArfC, were classified as type AXH-m,d enzymes. None of the arabinofuranosidases was able to degrade the double-arabinosylated xylooligosaccharides XA²⁺³XX. β-Xylosidase XylA (GH43) was able to degrade unsubstituted XOS, but showed limited activity to degrade AXOS.

On the ropivacaine-reducing effect of low-dose sufentanil in intrathecal labor analgesia

BACKGROUND

Combining ropivacaine with sufentanil for intrathecal (i.t.) analgesia in labor is well recognized, but information on dosing is limited. This study aimed to determine the ED 50 of i.t. ropivacaine and to assess the effect of adding defined low doses of sufentanil.

METHODS

This was a two-phase, double-blind, randomized and prospective study. One hundred and fifteen parturients receiving combined spinal epidural analgesia were allocated to one of four groups to receive ropivacaine or sufentanil alone or in combination. In phase one, sufentanil dose-response was calculated using logistic regression. In phase two, ED 50 of ropivacaine and of the combination with a fixed dosage of sufentanil at ED 20 and ED 40 was evaluated using the technique of up-down sequential allocation. Analgesic effectiveness was assessed 15 min after injection using a 100 mm visual analog scale, with <10 mm lasting for 45 min defined as effective. Furthermore, side effects and duration were recorded.

RESULTS

The ED 50 of i.t. ropivacaine was 4.6 mg [95% confidence intervals (95% CI) 4.28, 5.31]. Adding sufentanil at ED 20 significantly decreased the ED 50 of i.t. ropivacaine to 2.1 mg (95%CI 1.75, 2.5) (P<0.005); at ED 40, the reduction was similar (P<0.005). Combining sufentanil with ropivacaine resulted in a dose-independent prolongation of analgesia. Besides pruritus, which was well tolerated, there were no differences in side effects.

CONCLUSION

Adding sufentanil at ED 20 results in a more than 50% dose-sparing effect of ropivacaine and considerably prolongs analgesia. Increasing dosage implicates no clinical benefit.

Practical impact of the European Resuscitation Council's BLS algorithm 2005

BACKGROUND

The European Resuscitation Council (ERC) guidelines 2005 have brought major changes in the BLS algorithm. The aim of our investigation was to look for the practical impact of these modifications.

METHODS

In a randomized cross-over design we evaluated how adults would adhere to the BLS algorithm of the ERC guidelines 2000 (group A) compared to the guidelines 2005 (group B). The secondary endpoint was to determine the amount of time that elapsed before the start of the chest compressions in the two different groups. Participants were recruited from the streets and an office building of the Austrian Red Cross and were randomized to commence either with A or B. The volunteers were taught the allocated BLS sequence according to their group placement, and before evaluation each of the two groups was given the opportunity to train until they felt confident in using the algorithm. Performance during evaluation was documented automatically with a recording resuscitation manikin (Resusci-Anne, Skill Reporter).

RESULTS

Sixty people were included in the study, one individual dropped out after randomisation. In group A 9/59 (15.25%) participants followed the algorithm correctly versus 24/59 (40.68%) in group B (p=0.006). The time to start of chest compressions was significantly shorter in group B (21.31+/-7.11s), compared to group A (36.68+/-11.75s, p<0.01).

CONCLUSION

Compared to the 2000 BLS algorithm, the 2005 BLS sequence seems to be easier to learn and to retain, though nearly 60% of participants did not follow the new algorithm correctly. As expected, there was a significantly shorter time elapsing before the start of chest compressions when applying the 2005 algorithm. These findings should translate to better survival after cardiac arrest.

Restituting intestinal epithelial cells exhibit increased transducibility by adenoviral vectors

BACKGROUND AND AIMS

While mature enterocytes are resistant to transduction by adenovirus type 5 (Ad5) vectors, undifferentiated cells are transduced much more efficiently. Our purpose was to study enterocyte transduction in models of intestinal wound healing.

METHODS

Transduction was studied ex vivo using cultures of endoscopic biopsies and in vitro utilizing Caco-2 cells in models of mucosal wound healing. Vectors carried either the LacZ or the luciferase gene. CAR (coxsackievirus and adenovirus receptor) and integrins were studied with transduction inhibition and immunofluorescent staining.

RESULTS

Increased transduction efficiency was observed for a subset of enterocytes with a flattened de-differentiated phenotype present at the edge of cultured biopsies. In the in vitro systems, expanding Caco-2 cell monolayers exhibited increased transducibility that was time- and dose-dependent, reaching virtually 100% in cells along the leading edge at high viral load. Bioluminescence activity of transduced expanding monolayers was up to 3-fold greater than that of non-expanding monolayers ('fence' system, 48 h, MOI 1000, p < 0.05). Mitomycin C pre-treatment did not affect levels of transduction in expanding monolayers. At the highest viral load tested, CAR or integrin blocking prior to virus application resulted in 39.4% and 45.4% reduction in transduction levels (p < 0.05). Immunofluorescence revealed altered expression of CAR on the migrating edge of the Caco-2 cultures and the expression of CAR on the apical membrane of biopsy enterocytes.

CONCLUSIONS

Increased CAR and integrin accessibility in migrating enterocytes mediates increased transduction by Ad5 vectors. This subset of enterocytes provides a target for the delivery of genes of interest for both research and gene therapy applications.

Death in correctional facilities: opportunities for automated external defibrillation

BACKGROUND

Death due to cardiovascular disease occurs more frequently in prisons than the national average. Due to close surveillance 24 h/day, the ability to reach the patient within 3 min and time consuming access for the EMS crews, it was hypothesised that the deployment of automated external defibrillators (AEDs) might make improvements regarding Call-to-the-First-AED-Prompt (CTP) interval and formed the aim of this study.

METHODS

Our investigation was analysed on an intention to treat basis and conducted in a prospective, open and observational design. As the primary outcome, the CTP-intervals were compared to the arrival intervals of the EMS. As a secondary outcome, an analysis of all deceased inmates was described.

RESULTS

The average daily population of inmates in Austrian correctional facilities is 7714. During a period of 13 months, 10 instances in which an AED was activated and electrodes attached to a collapsed inmate, were reported. The CTP-interval (median+/-S.D.) was 2.3+/-1.6 S.D. min. It took the EMS 10.0+/-4.3 S.D. min. to arrive at the patient's side. Four out of 10 cases of cardiac arrest occurred due to myocardial infarction. Of 39 deceased inmates, a post mortem examination was completed in 34 cases. In 13 cases, cardiovascular disease was the cause of death.

DISCUSSION

The main finding was a four-fold reduction of the CTP-interval. This fact indicates the potential improvements which could be achieved with the deployment of AEDs. Our secondary objective revealed that death due to cardiovascular disease was found in a high proportion and could be considered to be a strong incentive to initiate programmes to counter cardiovascular death in prison.

Chimeric Ad5 Vectors Expressing the Short Fiber of Ad41 Show Reduced Affinity for Human Intestinal Epithelium

Altering adenovirus tropism has attracted increased attention in recent years to improve gene delivery. We constructed a recombinant Ad5 vector carrying the non-CAR (coxsackievirus and adenovirus receptor) binding short fiber of enterotropic Ad41 (Ad5SHORT) and tested its transduction efficiency on enterocytes. Ad5SHORT was engineered, in high titers similar to the parent vector, by homologous recombination in Escherichia coli BJ5183 (recBC sbcBC) and propagated on C7 cells. Western blotting confirmed the presence of Ad41 short fiber on Ad5SHORT while lack of CAR-binding was evident by the low transduction of CHO-CAR cells. Transduction efficiency of enterocytes, the natural target tissue for the fiber-"donor" virus Ad41, was tested in human intestinal biopsy cultures and in Caco-2 cells, including ulcerative colitis tissue and mucosal wound healing models. Ad5SHORT exhibited up to 23-fold lower transduction levels compared to Ad5 in human intestinal biopsy cultures and up to 13-fold in the in vitro systems. The differences with the in vitro systems were more pronounced when less differentiated cells were used. These studies highlight the potential for using this chimeric Ad5/Ad41 vector as a scaffold for the development of retargeted adenoviral vectors. Finally, our results suggest that the short fiber does not appear to be mediating, at least by itself, the increased enterocyte affinity of Ad41.

Increased transduction of human intestinal epithelial cells by adenoviral vectors in inflammatory bowel disease

BACKGROUND

Delivery of genes encoding anti-inflammatory proteins has been proposed as a strategy for the treatment of inflammatory bowel disease (IBD). The goal of this study was to assess the ability of a standard adenoviral vector to transfect epithelial cells in intestinal explants from patients with IBD compared with controls.

METHODS

Endoscopic colon biopsies obtained from patients with no history of IBD and endoscopically normal colon (n = 4), patients with a history of ulcerative colitis (UC; n = 5), and patients with a history of Crohn's disease (CD; n = 3) were placed in explant culture and exposed to an adenoviral vector carrying the nuclear targeted beta-galactosidase reporter gene.

RESULTS

X-Gal staining showed that the total number of transduced cells per square millimeter was greater in UC explants than in controls (mean, 11.3 versus 0.9 blue nuclei/mm, respectively; P < 0.02) and that the frequency of epithelial cell transduction was greater in UC explants than in controls (86% versus 47% of explants, respectively; P = 0.01). Transduction of mature columnar surface epithelial cells occurred exclusively in UC and CD explants and was not seen in controls. Attenuated epithelial cells at sites of tissue damage or ulceration showed increased transduction compared with mature columnar epithelial cells (62% versus 19% of occurrences, respectively; P < 0.0001).

CONCLUSIONS

We conclude that intestinal epithelial cells from IBD patients are more readily transfected by standard adenoviral vectors than are those from control patients. These results suggest that targeting genes to inflamed intestine through the luminal route may be possible.

Chemokine gene modification of human dendritic cell-based tumor vaccines using a recombinant adenoviral vector

Previous animal studies conducted in our laboratory have shown that tumor antigen-pulsed dendritic cells (TP-DC) can mediate antitumor effects in vivo. However, durable and complete regression of established tumors has been difficult to achieve through the administration of TP-DC alone. To better augment immune priming to tumors in vivo, we have hypothesized that it is necessary to achieve an increased number of host-derived, naïve T cells at the site of TP-DC vaccine injections. To accomplish this goal, we have embarked on a series of studies that utilize defined chemokines. One of these molecules, secondary lymphoid tissue chemokine (SLC), has been shown to be uniquely chemoattractant for naïve T cells and dendritic cells. We propose that gene modification of DC-based tumor vaccines to produce human SLC will enhance T-cell recruitment and immune priming to tumor-associated antigens, and thereby translate into improved antitumor vaccine efficacy in vivo. Utilizing an E1-, E3-deleted adenoviral vector containing the gene for human SLC, we have been able to transduce human DC to produce biologically active human SLC that chemoattracts human T cells in vitro. SLC production by transduced DC was markedly enhanced upon DC maturation. Additionally, these SLC-secreting DC were found to be viable to a large extent despite the cytopathic effect inherent in adenoviral gene transfer and, most importantly, functional as determined by their ability to prime autologous T cells to a known melanoma-associated antigen, MART-1. Based on these encouraging results, we plan to initiate Phase I clinical studies utilizing DC-SLC to treat patients with advanced solid tumors.

Highly efficient genetic transduction of primary human synoviocytes with concentrated retroviral supernatant

We are developing retroviral-mediated gene transfer to human fibroblast-like synovial cells (FLS) as one approach to characterizing genetic pathways involved in synoviocyte pathophysiology. Prior work has suggested that FLS are relatively refractory to infection by Moloney murine leukemia virus based vectors. To determine if viral titer influenced the transduction efficiency of FLS, we optimized a rapid, efficient, and inexpensive centrifugation method to concentrate recombinant retroviral supernatant. The technique was evaluated by measurement of the expression of a viral enhanced green fluorescent protein transgene in transduced cells, and by analysis of viral RNA in retroviral supernatant. Concentration (100-fold) was achieved by centrifugation of viral supernatant for four hours, with 100% recovery of viral particles. The transduction of FLS increased from approximately 15% with unconcentrated supernatant, to nearly 50% using concentrated supernatant. This protocol will be useful for investigators with applications that require efficient, stable, high level transgene expression in primary FLS.

Clinical protocol. Purging of autologous stem cell sources with bcl-x(s) adenovirus for women undergoing high-dose chemotherapy for stage IV breast carcinoma

High-dose chemotherapy (HDCT) and autologous bone marrow transplantation (BMT) is frequently used to treat patients with metastatic cancer including breast cancer and neuroblastoma. However, the bone marrow of such patients is often contaminated with tumor cells. Recently, we have found that a recombinant adenovirus vector that contains a bcl-x, minigene (a dominant negative inhibitor of the bcl-2 family), called the bcl-x(s) adenovirus, is lethal to cancer cells derived from epithelial tissues, but not to normal human hematopoietic cells. To determine the mechanism, by which this virus spares normal hematopoietic cells, we isolated normal mouse hematopoietic stem cells and infected them with an adenovirus that contains a beta-galactosidase minigene. Such cells do not express beta-galactosidase, indicating that hematopoietic stem cells do not express transgene encoded by adenovirus vectors based upon the RSV-AD5 vector system. When breast cancer cells mixed with hematopoietic cells were infected with the bcl-x(s) adenovirus, cancer cells were selectively killed by the suicide adenoviruses. Hematopoietic cells exposed to the suicide vectors were able to reconstitute the bone marrow of mice exposed to lethal doses of y-irradiation. These studies suggest that adenovirus suicide vectors may provide a simple and effective method to selectively eliminate cancer cells derived from epithelial tissue that contaminate bone marrow to be used for autologous BMT. We therefore propose to initiate a phase I clinical trial to test the safety of this virus in women with breast cancer undergoing high does chemotherapy and autologous BMT.

Trigonal-prismatic versus octahedral molecular structures in [CH3)nMX6-n]] compounds

The molecular structures of [(CH3)5MoOCH3], [(CH3)4Mo(OCH3)2], [(CH3)5WCl], and [(CH3)3WCl(OCH3)2] are reported. The first three structures are based on trigonal-prismatic geometry, the last one on octahedral geometry.

DNA-liposome versus adenoviral mediated gene transfer of transforming growth factor beta1 in vascularized cardiac allografts: differential sensitivity of CD4+ and CD8+ T cells to transforming growth factor beta1

We have developed a model of transforming growth factor (TGF)beta1 gene transfer into mouse vascularized cardiac allografts to study the use of gene transfer as an immunosuppressive therapy in transplantation. Donor hearts were perfused with either DNA-liposome complexes or adenoviral vectors that encode the active form of human TGFbeta1. DNA-liposome mediated transfection prolonged allograft survival in approximately two-thirds of transplant recipients, while adenoviral delivery of TGFbeta1 was not protective. Protective TGFbeta1 gene transfer was associated with reduced Th1 responses and an inhibition of the alloantibody isotype switch. The protective effects of TGFbeta1 gene transfer were overridden by exogenous interleukin-12 administration. Interestingly, alloreactive CD4+ and CD8+ cells exhibited distinct sensitivities to TGFbeta1 gene transfer: CD4+ Th1 function was abrogated by this modality, although CD8+ Th1 function was not. Transient depletion of recipient CD8+ cells markedly prolonged the survival of grafts transfected with either DNA-liposome complexes or adenoviral vectors. Transgene expression persisted for at least 60 days, and Th1 responses were not detectable until CD8+ T cells repopulated the periphery. However, long-term transfected allografts appeared to exhibit exacerbated fibrosis and neointimal development. These manifestations of chronic rejection were absent in long-term transfected isografts, suggesting that long-term expression of active TGFbeta1 alone is not sufficient to induce fibrosis of the grafts. Collectively, these data illustrate the utility of immunosuppressive gene therapy as a treatment for transplantation when combined with additional conditioning regimens. Further, they illustrate that alloreactive CD4+ and CD8+ cells may be differentially influenced by cytokine manipulation strategies.

Antitumor efficacy of tumor-antigen-encoding recombinant poxvirus immunization in Dunning rat prostate cancer: implications for clinical genetic vaccine development

One potential use for prostate-cancer-associated genes discovered through ongoing genetics studies entails the construction of virus- or plasmid-based recombinant vector vaccines encoding these new tumor-associated antigens (TAA) to induce TAA-specific immune responses for the prevention or therapy of prostate cancer. Clinical trials evaluating prototypes of such recombinant vaccines are under way. TAA-encoding recombinant vector vaccines, however, have not previously been evaluated in a prostate-cancer animal model. For assessment of the potential susceptibility of prostate cancer to genetic immunization strategies using TAA-encoding recombinant vectors, the antitumor efficacy of a model recombinant viral vector encoding a TAA was evaluated in rat Dunning prostate cancer. Recombinant vaccinia was chosen as a prototype virus vector encoding a TAA for these studies, and beta-galactosidase was chosen as a model target TAA. Dunning AT-2 cells were transduced with a retroviral vector to express beta-galactosidase, and the susceptibility of tumorigenic AT-2-lacZ cells to immunization with vaccinia-lacZ was measured using protection studies in Copenhagen and nu/nu rats. Stably transduced AT-2-lacZ cells expressing beta-galactosidase as measured by enzymatic substrate-based assays were found to retain their tumorigenicity in vivo despite abundant expression of rat major histocompatibility complex (MHC) class I. Immunization with model TAA-encoding recombinant vaccinia-lacZ conferred significant protection against subsequent growth of AT-2-lacZ cells in vivo (P = 0.01); however, the efficacy of such immunization was markedly dependent on the volume of tumor challenge. The antitumor efficacy of TAA-encoding recombinant vaccinia immunization was abrogated in nu/nu rats, suggesting a T-cell-dependent mechanism of activity. These studies suggest that prostate cancer may be a suitable target for immunization strategies using TAA-encoding recombinant vectors. Such immunization strategies may be more effective in settings of minimal cancer burden.

Adenovirus-mediated over-expression of interleukin-1 receptor antagonist reduces susceptibility to excitotoxic brain injury in perinatal rats

In seven-day-old rats, intracerebral injection of N-methyl-D-aspartate transiently stimulates expression of Interleukin-1 beta messenger RNA. To evaluate the role of Interleukin-1 beta in the pathogenesis of excitotoxic injury, we sought to determine if Interleukin-1 receptor antagonist, an endogenous competitive inhibitor of Interleukin-1 beta, could attenuate N-methyl-D-aspartate-induced injury. To induce sustained over-expression of Interleukin-1 receptor antagonist in the brain, a recombinant adenovirus encoding Interleukin-1 receptor antagonist was administered by intracerebroventricular injection into three-day-old rats. Increased brain concentrations of Interleukin-1 receptor antagonist two to six days later were documented by assays of tissue homogenates and by immunocytochemistry. To evaluate the impact of Interleukin-1 receptor antagonist on N-methyl-D-aspartate neurotoxicity, three-day-old animals received intracerebroventricular injections of either adenovirus encoding Interleukin-1 receptor antagonist or a control adenovirus encoding beta-galactosidase, followed four days later by right intrastriatal injections of N-methyl-D-aspartate (10 nmol/0.5 microliter), a dose that typically elicits excitotoxic injury in the ipsilateral striatum and adjacent hippocampus, or saline. Animals were killed five days later, and brain damage was quantitated by measurement of bilateral cross-sectional areas of the striatum and anterior hippocampus. In three independent experiments, in N-methyl-D-aspartate-lesioned animals, both striatal and hippocampal injuries were reduced in animals that had been infected with adenovirus that encoded Interleukin-1 receptor antagonist, in comparison with littermates infected with the control adenovirus (right striatal volume loss ranged from 16 to 24%, compared with 54-65% volume loss in control). There was no striatal atrophy in adenovirus-infected saline-injected animals. These results provide strong support for the hypothesis that Interleukin-1 beta is a mediator of excitotoxic brain injury in perinatal rats.

Fluid trapping of erythrocytes under hypoosmolar conditions

125I albumin was used to assess the amount of trapped fluid after microhematocrit centrifugation of erythrocytes suspended in buffers of different osmolality. Surprisingly the total amount of trapped fluid per volume unit of packed erythrocytes decreased with decreasing osmolality of the suspending buffer despite erythrocyte swelling. However, if the contribution of the individual erythrocyte to the trapped fluid was calculated, the trapped fluid per erythrocyte did not change between 311 mosm/kg and 256 mosm/kg. For osmolalities below 256 mosm/kg a significant increase of trapped fluid was obtained. It is concluded that the packing ability of erythrocytes is not impaired in suspending fluid of moderate to severe infraphysiological tonicity. The daily clinical experience that considerable degrees of plasma hypoosmolality are tolerated in vivo without hemolysis or impairment of oxygen transport by erythrocytes may be explained by the excellent ability of shape adaptation of erythrocytes to each other and to other surfaces such as vascular endothelia. The method of trapped fluid determination might be of potential value as a complementary method in the evaluation of erythrocyte rheology if the amount of trapped fluid is related to the individual erythrocyte.

The mean red cell volume in long distance runners

Red cell indices were determined in 6 well trained runners before and after a 100 km race, and Coulter Counter (CC) determinations compared with calculated values derived from centrifuged hematocrit (ctrf), red cell count (CC) and hemoglobin measurements. The following changes were observed immediately after the race, as compared to values 3 days before: MCV(ctrf) decreased by 4.9% (p less than 0.001), MCV(CC) increased by 1.9% (p less than 0.05), MCHC(ctrf) increased by 4% and MCHC(CC) decreased by 3%. The increase in MCV(CC) suggests that intraerythrocyte osmolality was increased, this probably leading to swelling of the cells induced by a shift of water from the diluting Coulter Counter solution into the red cells prior to the MCV measurement. The decrease in MCV(ctrf) immediately after the race was not correlated with the increase in plasma osmolality. This suggests that plasma osmolality alone was not the key factor for regulation of red cell volume. The changes in MCV(ctrf), which contributed to a surprising stability of the hematocrit value and plasma volume, might represent a physiological principle for the maintenance of a favourable blood viscosity.

Creatine kinase and creatine kinase MB in endurance runners and in patients with myocardial infarction

Following a 100 km race creatine kinase (CK) creatine kinase MB (CKMB) activities were serially measured in well trained athletes and compared with enzyme activities in patients with acute myocardial infarction (AMI). The half-time of disappearance of CK (CKt1/2) was 1.75 +/- 0.70 days in runners who trained within the 1st week after the race, and was 0.81 +/- 0.18 days in patients with AMI, P less than 0.005. CKt1/2 in runners was shorter (1.17 +/- 0.28 days) when no training was performed in the first postrace week. CKt1/2 was linearly correlated with age (P less than 0.01) in the runners but not in the patients. CKMBt1/2 was 1.30 and 1.11 days in two runners and 0.56 +/- 0.10 days in patients with AMI (P less than 0.05). In line with histologic and enzymatic findings in skeletal muscle of long distance runners as reported by other workers, our kinetic data provide further evidence that CK and CKMB are released from muscular compartments in runners other than those in patients with AMI.