A uniform method for the simultaneous blood group phenotyping of Fya , Fyb , Jka , Jkb , S, sÌ , P1, k applying lateral-flow technique.

BACKGROUND AND OBJECTIVES: A lateral flow assay for simultaneous blood group typing of ABO, RhD, C, E, c, e, Cw and K with stable end-point and without centrifugation is in routine use since several years (MDmulticard® ). The typing of extended phenotype parameters belonging to the Duffy, Kidd, MNSs blood group systems and others, however, has not yet been demonstrated for this technique. Reliable detection of Fyx , a weak Fyb phenotype with a pronounced quantitative reduction of the number of Fyb antigens on the erythrocyte surface, remains a weakness of current serological blood grouping techniques. MATERIAL AND METHODS: The performance characteristics of the following reagents were evaluated in donor and patient samples in lateral flow technology (MDmulticard® ): Anti-Fya , -Fyb , -Jka , -Jkb , -S, -s̅, -P1 and -k. The sensitivity to detect Fyx was in addition evaluated with Fyx positive samples, which had been preselected by MALDI-TOF MS-based genotyping. RESULTS: All results obtained with the MDmulticard® were in full accordance with those of the CE-certified reference products for all the eight reagent formulations used: Anti-Fya , -Fyb , -Jka , -Jkb , -S, -s̅, -P1 and -k. Also, all Fyx phenotypes of the selected population of 93 positive samples, originally identified by MALDI-TOF MS-based genotyping, were reliably detected by the lateral flow assay. CONCLUSION: Extended phenotype blood group parameters, including the serologically challenging Fyx phenotype, can be determined simultaneously, rapidly and accurately using the lateral flow (MDmulticard® ) technology, even in cases when IgG class antibodies are the only source of diagnostic antibodies.

The VKORC1 and CYP2C9 genotypes significantly effect Vitamin K antagonist dosing only in patients over the age of 20years.

INTRODUCTION: Given the qualitative differences in the role of VKORC1 and CYP2C9 polymorphisms in Vitamin K antagonists (VKA) dosing variation between adults and children, we were interested in determining at what age these polymorphism begin to play a more significant role. METHODS: A prospective cohort study of 190 patients aged 1-86years receiving VKA for treatment of venous thromboembolism. Blood samples were collected beyond the acute thrombotic event when patients were on stable targeted INR (2-3) for plasma testing and VKORC1/CYP2C9 genotyping. Patient demographics including VKA dose were collected. Simple and multiple linear regression was used to assess the relationship of VKA dose with polymorphisms and weight, adjusted for quality of anticoagulation (INR, D-Dimer), liver (AST, ALT) and renal function. RESULTS: In subjects 1-19years of age, weight explained 39.0% of dosing variation with VKORC1 and CYP2C9 playing a minor role. In contrast, in subjects 20-40years weight contributed 23%, VKORC1 44% and CYPC29 49% of the VKA dose variation. CONCLUSION: Until the age of 19, weight has a far greater effect on VKA dosing variation than VKORC1 and CYP2C9 polymorphisms. During the age of 20-40years, VKORC1 and CYP2C9 play a significant role.

Pathogen-reduced Ebola virus convalescent plasma: first steps towards standardization of manufacturing and quality control including assessment of Ebola-specific neutralizing antibodies.

BACKGROUND: Ebola virus disease is a public health emergency of international concern, and enormous efforts are being made in the development of vaccines and therapies. Ebola virus convalescent plasma is a promising anti-infective treatment of Ebola virus disease. Therefore, we developed and implemented a pathogen-reduced Ebola virus convalescent plasma concept in accordance with national, European and global regulatory framework. MATERIALS AND METHODS: Ebola virus convalescent plasma manufacture and distribution was managed by a collection centre, two medical centres and an expert group from the European Blood Alliance. Ebola virus convalescent plasma was collected twice with an interval of 61 days from a donor recovering from Ebola virus disease in Germany. After pathogen reduction, the plasma was analysed for Ebola virus-specific immunoglobulin G (IgG) antibodies and its Ebola virus neutralizing activity. RESULTS: Convalescent plasma could be collected without adverse events. Anti-Ebola virus IgG titres and Ebola-specific neutralizing antibodies in convalescent plasma were only slightly reduced after pathogen reduction treatment with S59 amotosalen/UVA. A patient in Italy with Ebola virus disease was treated with convalescent plasma without apparent adverse effects. DISCUSSION: As proof of principle, we describe a concept and practical implementation of pathogen-reduced Ebola virus convalescent plasma manufacture, quality control and its clinical application to an Ebola virus disease patient.

Patient Blood Management in Europe: surveys on top indications for red blood cell use and Patient Blood Management organization and activities in seven European university hospitals.

BACKGROUND AND OBJECTIVES: Patient Blood Management (PBM) in Europe is a working group of the European Blood Alliance with the initial objective to identify the starting position of the participating hospitals regarding PBM for benchmarking purposes, and to derive good practices in PBM from the experience and expertise in the participating teams with the further aim of implementing and strengthening these practices in the participating hospitals. METHODS: We conducted two surveys in seven university hospitals in Europe: Survey on top indications for red blood cell use regarding usage of red blood cells during 1 week and Survey on PBM organization and activities. RESULTS: A total of 3320 units of red blood cells were transfused in 1 week at the seven hospitals. Overall, 61% of red cell units were transfused to medical patients and 36% to surgical patients, although there was much variation between hospitals. The organization and activities of PBM in the seven hospitals were variable, but there was a common focus on optimizing the treatment of bleeding patients, monitoring the use of blood components and treatment of preoperative anaemia. CONCLUSION: Although the seven hospitals provide a similar range of clinical services, there was variation in transfusion rates between them. Further, there was variable implementation of PBM activities and monitoring of transfusion practice. These findings provide a baseline to develop joint action plans to further implement and strengthen PBM across a number of hospitals in Europe.

[Cost analysis of patient blood management]. / Kostenanalyse eines Patient-Blood-Management-Konzepts.

BACKGROUND: Patient blood management (PBM) is a multidisciplinary approach focusing on the diagnosis and treatment of preoperative anaemia, the minimisation of blood loss, and the optimisation of the patient-specific anaemia reserve to improve clinical outcomes. Economic aspects of PBM have not yet been sufficiently analysed. OBJECTIVES: The aim of this study is to analyse the costs associated with the clinical principles of PBM and the project costs associated with the implementation of a PBM program from an institutional perspective. MATERIALS AND METHODS: Patient-related costs of materials and services were analysed at the University Hospital Frankfurt for 2013. Personnel costs of all major processes were quantified based on the time required to perform each step. Furthermore, general project costs of the implementation phase were determined. RESULTS: Direct costs of transfusing a single unit of red blood cells can be calculated to a minimum of €147.43. PBM-associated costs varied depending on individual patient requirements. The following costs per patient were calculated: diagnosis of preoperative anaemia €48.69-123.88; treatment of preoperative anaemia (including iron-deficiency anaemia and megaloblastic anaemia) €12.61-127.99; minimising perioperative blood loss (including point-of-care diagnostics, coagulation management and cell salvage) €3.39-1,901.81; and costs associated with the optimisation of the tolerance to anaemia (including patient monitoring and volume therapy) €28.62. General project costs associated with the implementation of PBM were €24,998.24. CONCLUSIONS: PBM combines various alternatives to the transfusion of red blood cells and improves clinical outcome. Costs of PBM vary from institution to institution and depend on the extent to which different aspects of PBM have been implemented. The quantification of costs associated with PBM is essential in order to assess the economic impact of PBM, and thereby, to efficiently re-allocate health care resources. Costs were determined at a single university hospital. Thus, further analyses of both the costs of transfusion and the costs of PBM-principles will be necessary to evaluate the cost-effectiveness of PBM.

Association between phenotype and genotype in carriers of haemophilia A.

Female carriers of haemophilia might suffer from increased bleeding tendency therefore the assessment of the bleeding risk is very important for improving care. This single-centre study documents the occurrence of bleedings in 46 carriers of haemophilia A including bleeding after tooth extraction (77%), easy bruising (67%), postsurgical bleeding (61%), menorrhagia (50%) or prolonged postpartum bleeding (43%). The F8 gene mutation of all 46 carriers (median age: 36.5 years, 15-80 years; mean FVIII:C activity: 59 ± 24.45%; normal range: 64-167%) was determined, and family history of haemophilia was recorded. For analysis, the bleeding tendency of the carriers was differentiated by severity into three groups. There was no statistically significant difference of FVIII:C between these groups. However, a correlation was found between the severity of bleeding tendency and the type of F8 gene mutation (P < 0.05) as well as the severity of haemophilia in affected male relatives (P < 0.0005). Results show that even carriers with a FVIII:C activity as high as 50-60% are at increased risk of bleeding. Incidence and intensity of bleeding symptoms of haemophilia A carriers are high and correlated with the phenotype of the male haemophilic relative and the underlying F8 gene mutation.

DNA excision repair and DNA damage-induced apoptosis are linked to Poly(ADP-ribosyl)ation but have different requirements for p53.

Poly(ADP-ribose) polymerase (PARP) is a DNA binding zinc finger protein that catalyzes the transfer of ADP-ribose residues from NAD(+) to itself and different chromatin constituents, forming branched ADP-ribose polymers. The enzymatic activity of PARP is induced upon DNA damage and the PARP protein is cleaved during apoptosis, which suggested a role of PARP in DNA repair and DNA damage-induced cell death. We have generated transgenic mice that lack PARP activity in thymocytes owing to the targeted expression of a dominant negative form of PARP. In the presence of single-strand DNA breaks, the absence of PARP activity correlated with a strongly increased rate of apoptosis compared to cells with intact PARP activity. We found that blockage of PARP activity leads to a drastic increase of p53 expression and activity after DNA damage and correlates with an accelerated onset of Bax expression. DNA repair is almost completely blocked in PARP-deficient thymocytes regardless of p53 status. We found the same increased susceptibility to apoptosis in PARP null mice, a similar inhibition of DNA repair kinetics, and the same upregulation of p53 in response to DNA damage. Thus, based on two different experimental in vivo models, we identify a direct, p53-independent, functional connection between poly(ADP-ribosyl)ation and the DNA excision repair machinery. Furthermore, we propose a p53-dependent link between PARP activity and DNA damage-induced cell death.

High-level expression of the retinoic acid receptor beta gene in normal cells of the uterine cervix is regulated by the retinoic acid receptor alpha and is abnormally down-regulated in cervical carcinoma cells.

Retinoic acid (RA) is essential for regulation of epithelial cell differentiation. The intracellular effects of RA are mediated by RA-binding nuclear receptors, including the RA receptors (RARs) alpha, beta, and gamma. The ligand-activated receptors induce the transcription of target genes by binding to RA-responsive elements in the promoter regions. One target gene is the RAR beta gene, which encodes a potential tumor suppressor. Loss of RA inducibility of RAR beta gene expression is assumed to play a role in the development of several types of human carcinomas, including carcinomas of the uterine cervix. We have analyzed RAR beta gene expression in normal cervical cells and in cervical carcinoma cell lines. The results show that the RAR beta mRNA levels are high and RA inducible in the primary keratinocytes, whereas they are low and not inducible or only slightly inducible by RA in all of the cervical carcinoma cell lines analyzed. The basal and the RA-induced RAR beta mRNA levels tend to increase with senescence of the normal cells. Fusion of primary ectocervical keratinocytes with HeLa cervical carcinoma cells revealed that the characteristics of RAR beta gene expression of the normal cells are dominant over that of the tumor cells. Using synthetic retinoids with receptor-preferential agonist activities and a RAR alpha-specific antagonist, we show that RAR alpha is the major endogenous RAR subtype for induction of RA-dependent RAR beta gene expression. Taken together, our results indicate that abnormal downregulation of RAR beta gene expression may be an important step in the multifactorial process of cervical carcinogenesis.

[Patient blood management: Current state of the literature]. / Patient-blood-Management : Stand der aktuellen Literatur.

BACKGROUND: Preoperative anemia has a prevalence of approximately 30% and is one of the strongest predictors of perioperative red blood cell (RBC) transfusion. It is rarely treated although it is an independent risk factor for the occurrence of postoperative complications. Additionally, the high variability in the worldwide usage of RBC transfusions is alarming. Due to these serious deficits in patient care, in 2011 the World Health Organization recommended the implementation of a patient blood management (PBM). OBJECTIVES: This article provides information about PBM as a multidimensional and interdisciplinary approach. MATERIAL AND METHODS: A selective literature search was carried out in the Medline and Cochrane library databases including consideration of national and international guidelines. RESULTS: A PBM promotes the medically and ethically appropriate use of all available resources, techniques and materials in favor of an optimized perioperative patient care. Patients' own resources should be specifically protected, strengthened and used and include (i) diagnosis and therapy of preoperative anemia, (ii) minimizing perioperative blood loss, (iii) blood-conserving surgical techniques, (iv) restriction of diagnostic blood sampling, (v) utilization of individual anemia tolerance, (vi) optimal coagulation and hemotherapy concepts and (vii) guideline-based, rational indications for the use of RBC transfusions. CONCLUSION: A PBM should be advocated as an incentive to evaluate and critically optimize local conditions. An individual, interdisciplinarily structured bundle of different PBM measures has great potential to optimize the quality of patient care and to make it safer.

Mutual requirement of CDK4 and Myc in malignant transformation: evidence for cyclin D1/CDK4 and p16INK4A as upstream regulators of Myc.

We demonstrate in this paper that CDK4 which is a G1 phase specific cell cycle regulator and catalytic subunit of D-type cyclins has oncogenic activity similar to D-type cyclins themselves and is able to provoke focus formation when cotransfected with activated Ha-ras into primary rat embryo fibroblasts. Surprisingly, using two different mutants we show that CDK4's ability to bind to p16INK4a and not its kinase activity is important for its transforming potential. In addition, p16INK4a but not a mutant form that is found in human tumours can completely abrogate focus formation by CDK4 suggesting that CDK4 can malignantly transform cells by sequestering p16INK4a or other CKIs. We demonstrate that both cyclin D1 and CDK4 functionally depend on active Myc to exert their potential as oncogenes and vice versa that the transforming ability of Myc requires functional cyclin D/CDK complexes. Moreover, we find that p16INK4a and the Rb related protein p107 which releases Myc after phosphorylation by cyclin D1/CDK4 efficiently block Myc's activity as a transcriptional transactivator and as an oncogene. We conclude that both p16INK4a and cyclin D/CDK4 complexes are upstream regulators of Myc and directly govern Myc function in transcriptional transactivation and transformation via the pocket protein p107.

Uncoupling of p21WAF1/CIP1/SDI1 mRNA and protein expression upon genotoxic stress.

The p21WAF1/CIP1/SDI1 gene is an important regulator of crucial cellular processes, including cell cycle control, cellular differentiation, and the response to genotoxic stress. Induction of p21 gene expression upon DNA damage is widely believed to be p53-dependent. In the present study we analysed the expression of p21 following genotoxic stress, using different DNA-damaging agents and cellular systems. We found that the p21 response markedly varied between different cell lines and also for different genotoxic agents within the same cell line. Genotoxic induction of p21 mRNA expression can occur in the presence of p53-antagonists, such as overexpressed mdm-2 or human papillomavirus (HPV) E6, and in cells harbouring mutated p53 genes. Moreover, upon genotoxic stress, p21 mRNA and protein expression were found to be uncoupled in several cell lines. Thus, transcriptional and postranscriptional changes in p21 expression following DNA damage are not necessarily linked to the intracellular p53 status but strongly depend on the individual cellular background and the type of DNA-damaging agent. Our findings indicate that p21 expression following genotoxic stress underlies a complex control and can be substantially modulated on the posttranscriptional level in a cell-specific manner.

Investigation of the cell cycle regulation of cdk3-associated kinase activity and the role of cdk3 in proliferation and transformation.

The G1-S transition in mammalian cells has been demonstrated to require the cyclin-dependent kinases cdk2, cdk3 and cdk4/6. Here we show that a novel kinase activity associated with cdk3 fluctuates throughout the cell cycle differently from the expression of cyclin D1-, E- and A-associated kinase activities. Cdk3 kinase activity is neither affected by p16 (in contrast to cdk4/6) nor by E2F-1 (in contrast to cdk2), but is downregulated upon transient p27 expression. We found cdk3 to bind to p21 and p27. We provide evidence that p27 could be involved in the regulation of the cell cycle fluctuation of cdk3 activity: cdk3 protein does not fluctuate and interaction of cdk3 with p27, but not with p21, is lost when cdk3 kinase becomes active during the cell cycle. In Myc-overexpressing cells, but not in normal Ratl cells, constitutive ectopic expression of cdk3 induces specific upregulation of cdk3-associated kinase activity that is still cell cycle phase dependent. Ectopic cdk3, but not cdk2, enhances Myc-induced proliferation and anchorage-independent growth associated with Myc activation, without effects on cyclin D1, E and A protein expression or kinase activities. High levels of cdk3 in Myc-overexpressing cells trigger up- and deregulation of E2F-dependent transcription without inducing the E2F-DNA binding capacity. In contrast to all other studied positive G regulators, cdk3 is unable to cooperate with ras in fibroblast transformation suggesting a function of cdk3 in G1 progression that is different from cyclin D- or E-associated kinase activities. Our data provide first insights into the regulation of cdk3-associated kinase activity and suggest a model how cdk3 participates in the regulation of the G1-S transition.

Malignant transformation by cyclin E and Ha-Ras correlates with lower sensitivity towards induction of cell death but requires functional Myc and CDK4.

We demonstrate in this paper that the G1 phase specific cell cycle regulator cyclin E is able to provoke focus formation when cotransfected with activated Ha-ras into primary rat embryo fibroblasts (REFs). Cyclin E/Ha-ras transformed cells are highly tumorigenic in synergeneic rats, are able to form colonies in soft agar and show protection towards apoptosis upon serum starvation or DNA damage compared to cells transformed by the combination of Myc, cyclin D1 or SV40 large T-antigen and Ha-ras. Lines that were established after cyclin E/Ha-ras or cyclin D1/Ha-ras transformation contain a large percentage of polyploid cells. This was not observed in cells transformed with other oncoproteins and Ha-ras pointing to an involvement of D- and E type cyclins in genomic instability. The cyclin dependent kinase inhibitors p21 and p27 but also p16 completely abrogate focus formation by cyclin E and Ha-ras suggesting that the oncogenic activity of cyclin E still requires functional G1 specific cyclin/CDK complexes. Moreover, inhibition of Myc function also blocks the oncogenic activity of cyclin E indicating a requirement of Myc for cyclin E function. The findings presented here demonstrate that cyclin E can act as an oncoprotein with a potential involvement in genomic instability and the prevention of cell death. Our data also present more evidence for a strict functional interdependency between G1 cyclin/CDK complexes and c-Myc.

Sulindac sulfide inhibits Ras signaling.

The non-steroidal anti-inflammatory drug sulindac is used in cancer prevention and therapy, but the molecular aspects of its anti-tumor effect remain unresolved. In vivo the prodrug sulindac, is converted into the metabolite sulindac sulfide. We found that sulindac sulfide strongly inhibits Ras induced malignant transformation and Ras/Raf dependent transactivation. Sulindac sulfide decreases the Ras induced activation of its main effector, the c-Raf-1 kinase. In vitro sulindac sulfide directly binds to the Ras gene product p21ras in a non-covalent manner. Moreover, we can show that sulindac sulfide inhibits the interaction of p21ras with the p21ras binding domain of the Raf protein. In addition, sulindac sulfide can impair the nucleotide exchange on p21ras by CDC25 as well as the acceleration of the p21ras GTPase reaction by p120GAP. Due to its action at the most critical site in Ras signaling we propose sulindac sulfide as a lead compound in the search for novel anti-cancer drugs which directly inhibit Ras mediated cell proliferation and malignant transformation.

Functional p53 protein in human papillomavirus-positive cancer cells.

There is accumulating evidence that the p53 protein contributes to tumor suppression by stimulating the transcription of specific cellular genes, such as the cell cycle control gene WAF1/ClP1. p53-mediated transcriptional activation is inhibited in cotransfection assays by overexpressed E6 protein from cancer-associated human papillomavirus (HPV) types, pointing at a possible molecular mechanism by which these viruses contribute to malignant cell transformation. Here we analysed the transcriptional transactivation function of endogenous p53 protein in a series of cervical cancer cell lines, which express the E6 gene from integrated viral sequences. Transient and stable transfection analyses employing p53-responsive reporter constructs indicated that HPV-positive cervical cancer cells contained transactivating p53 protein. Treatment of HPV-positive cells with genotoxic agents, such as mitomycin C, cisplatin, or u.v. irradiation, resulted in an increase of nuclear p53 protein levels and enhanced binding of p53 to a p53-recognition site. These effects were accompanied by an increase of WAF1/ClP1 mRNA levels. In several HPV-positive cell lines, these molecular events were linked to a cell cycle arrest in G1. In contrast, cancer cells containing mutant p53 genes did not contain transactivating endogenous p53 protein and lacked the p53-mediated response to DNA damaging agents. These results indicate that the tumorigenic phenotype of HPV-positive cancer cell lines does not necessarily correlate with a lack of basal or DNA damage induced p53 activities and that therefore the presence of high risk HPV sequences is not functionally equivalent to the loss of p53 function through somatic mutations of the p53 gene.

Oncogenic potential of cyclin E in T-cell lymphomagenesis in transgenic mice: evidence for cooperation between cyclin E and Ras but not Myc.

To study the oncogenic activity of cyclin E in an in vivo system we generated transgenic mice expressing high levels of cyclin E in T-lymphocytes by using a construct containing the CD2 locus control region. These animals were neither predisposed to develop any tumors spontaneously nor showed an increased incidence when crossbred with Emu L-myc transgenic mice but developed hyperplasia in peripheral lymphoid organs at later age with an incidence of 27%. When treated with the DNA methylating carcinogen N-methylnitrosourea (MNU) that provokes the development of T-cell lymphomas, CD2-cyclin E transgenic animals came down with T-cell neoplasia showing a significant higher incidence (54%) than normal non transgenic controls (31%). In one of eight tumors that arose in normal MNU treated mice we could find an expected activating point mutation in the Ki-ras gene (12.5%). In contrast, the same mutation occurred in five of 16 tumors from CD2-cyclin E transgenic mice (31.2%). Whereas cyclin E overexpression alone did not lead to an increased CDK2 activity we observed in all tumors that emerged from either MNU treated normal mice or treated CD2-cyclin E transgenics a downregulation of p27KIP1 and a higher histone H1 kinase activity in CDK2 immunoprecipitates compared to normal tissue. These findings demonstrate that high level expression of cyclin E can predispose T-cells for hyperplasia and malignant transformation. However, the results also suggest that this activity of cyclin E is manifest only when other cooperating oncogenes in particular ras genes are present and activated. This would be consistent with our previous finding that cyclin E and Ha-Ras cooperate in focus formation assays in rat embryo fibroblasts.

Induction of the p53-target gene GADD45 in HPV-positive cancer cells.

The E6 oncoprotein of human papillomaviruses (HPVs) has the potential to functionally antagonize p53. In several experimental model systems, ectopic expression of E6 can block the genotoxic induction of the growth inhibitory p53 target gene gadd45, suggesting that the inactivation of this pathway may play a major role for HPV-associated cell transformation. Here, we investigated whether this reflects the regulation of gadd45 expression in carcinoma-derived HPV-positive cells. We found that the gadd45 gene is efficiently induced by mitomycin C, cisplatin, and UV irradiation in a series of HPV-positive cervical cancer cell lines. Moreover, clear induction of gadd45 gene expression was also observed following treatment with gamma-irradiation, a pathway that is strictly dependent on functional p53. This contrasted with findings in human foreskin keratinocytes experimentally immortalized by expressing the HPV16 E6, E7, or E6/E7 oncogenes from the heterologous CMV promoter, where expression of the E6 gene was linked to a lack of gadd45 induction following gamma-irradiation. These results indicate (1) that the tumorigenic phenotype of HPV-positive cancer cells is not linked to an inability to induce the gadd45 gene following DNA damage, (2) that experimental model systems in which the E6 gene is expressed ectopically and/or in a different cellular context do not necessarily reflect the regulation of p53-associated pathways in HPV-positive cancer cells and (3) that a pathway strictly depending on functional p53 is inducible in HPV-positive cancer cells, providing direct evidence that the endogenous p53 protein in these cells is competent to activate a cellular target gene, despite coexpression of the viral E6 oncogene.

Effect of long-term hypoxia on oxygen transport properties of blood in pregnant guinea pigs.

Pregnant guinea pigs undergoing long-term hypoxia were studied and the results compared with those of control animals (pregnant, but non-hypoxic). Hypoxic animals demonstrated a decrease of O2 affinity (-7%) and an increase of O2 capacity (+35%). In addition, the HCT was found to be higher in the hypoxic group (+41%), causing haemorheological disadvantages; in a shear model study the blood of hypoxic animals had to be exposed to the gas compartment of the rheo-oxymeter up to 62% longer than that of the control group. We have postulated, that this rheological impairement is compensated, since no abnormalities in number and abortion rate of fetuses (due to a possible O2 delivery impairment) were found. Our morphological studies in fact support this opinion, showing e.g. more capillary branchings and loops and a reduction of diffusion distances between maternal and fetal blood in hypoxic guinea pig placentae. The results emphasize the importance of more detailed rheological studies in connection with other investigations for a complete description of compensatory mechanisms.

Alterations of the fetal capillary bed in the guinea pig placenta following long-term hypoxia.

Oxygen supply is an important regulator of the fetal placental capillarization. To determine the effects of long-term hypoxia on the fetal placental vessel arrangement pregnant guinea pigs were kept under hypoxic conditions (12% O2 for 45 days). Vessel casts showed a significant difference in branching and orientation of the vessels between the controls and the hypoxic animals. The hypoxic group had a less orientated capillary bed with increased branching and coiling. By light- and transmission electron microscopical studies, there was a decreased diffusion distance, a decreased diameter of the fetal capillaries, and an increased number of capillary cross-sections. These results are consistent with the hypothesis that chronic hypoxia is responsible for increased branching and coiling of the capillaries resulting in a dense network of short and narrow capillaries in the placenta.