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Circulation time (Ct) between lung and periphery may be a surrogate for cardiac output, estimated here, for the most part, as the time between taking a breath of nitrogen and peripheral detection of a desaturation pulse. Use of pulse oximetry involves an internal, instrument delay; however, using the ear, we found shortening with exercise (12.1 ± 0.37 sec, at rest; 9.1 ± 0.25 sec at 100 watts), lengthening after β-blockade, and lengthening in patients with echocardiographic and clinical left heart failure (8 patients 16.2 ± 1.1 sec; 6 controls 12.0 ± 0.5 sec). Pulse oximetry failed, however, to discriminate heart failure from normal in several patients. In patients referred to a department of nuclear medicine for assessment of chest pain, pulse oximetry (finger and ear) showed unacceptable variability. Nuclide delays between lung and carotid artery correlated significantly with the reciprocal of gated SPECT estimated cardiac output (Q); not so, however, for lung to finger. In normal subjects, an old Waters fast response oximeter gave short, reproducible Ct estimates and a significant correlation with the reciprocal of (indirect Fick) cardiac output (Q). The relationship for normal subjects was: Ct=0.28 x 60/Q+2.8 sec (Q in L min.; slope < .001).

We demonstrate, theoretically, that oxygen diffusion distance is related to the metabolic rate of tumors (QO) as well as the oxygen tension. The difference in QO rate between tumors can vary by as much as 80-fold. Inhibition of oxygen utilization by glucose or chemical inhibitors can improve the diffusion distance. Combining respiratory inhibitors with increased availability of oxygen will further improve the oxygen diffusion distance for all tumors. A simple means for inhibiting oxygen consumption is the use of glucose (the Crabtree effect). The inhibition of tumor oxygen utilization by glucose occurs in R323OAc mammary carcinoma and 9L glioma cells. However, stimulation of oxygen consumption is observed with glucose in the Q hepatoma cell line. MIBG, a known inhibitor of oxygen utilization, blocks oxygen consumption in 9L, but is weakly inhibitory with the Q. Q tumor cells demonstrate an anomalous behavior of glucose and MIBG on oxygen consumption. Our results clearly demonstrate the necessity for comparing effects of different agents on different tumor cells. Generalizations cannot be made with respect to the choice of inhibitor for use. Our work shows that oxygen consumption also can be inhibited with malonate and chlorosuccinate. These substrates may be effective , where glucose is low and glutamine is the major substrate. Our results indicate that information about individual tumor substrate-linked metabolic controls may be necessary before attempting to inhibit oxygen utilization for therapeutic benefit.

We have previously demonstrated the successful use of skin oxygen saturation (SO) measurements to predict the healing viability in lower limb amputations for critical limb ischaemia. The measurements are quick and easy to perform, but the instrument that has been used to date is now obsolete and a new, lightweight, portable instrument has recently been introduced. However, fundamental differences between the two instruments could influence the criteria used for determining amputation level viability. The purpose of this study was to compare the measurements using the two instruments in order to validate amputation level viability criteria using the RM200.

Skin SO measurements were carried out on critically ischaemic lower limbs of patients, and on the forearms of normal volunteers during before, during and after a 5 minute period of tourniquet ischaemia. A linear correlation (r = 0.91) was found between the values obtained from the two instruments within the range of interest (0 to 40% SO). Differences between the instruments lay within 1 standard deviation of the mean, demonstrating a high degree of agreement between the two methods. The RM200 is thus an acceptable replacement for the MCPD instrument for amputation level viability assessments.

Heterogeneously distributed hypoxic areas are a characteristic property of locally advanced breast cancers. Hypoxia results from an imbalance between the supply and consumption of oxygen (O). Major pathogenetic mechanisms for the emergence of hypoxia are (i) structural and functional abnormalities in the tumor microvasculature, (ii) an adverse diffusion geometry, and (iii) tumor-related and therapy-induced anemia leading to a reduced O transport capacity of the blood. There is pronounced intertumor variability in the extent of hypoxia, which is independent of clinical size, stage, histology and grade. Hypoxia is intensified in anemic patients, especially in tumor (areas) with low perfusion rates.

Tumor hypoxia is a therapeutic problem since it makes solid tumors resistant to sparsely ionizing radiation, some forms of chemotherapy, and photodynamic therapy. However, besides more direct mechanisms involved in the development of therapeutic resistance, there are, in addition, indirect machineries that can cause barriers to therapies. These include hypoxia-mediated alterations in gene expression, proteomic and genomic changes, and clonal selection. These in turn can drive subsequent events that are known to further increase resistance to therapy in addition to critically affecting long-term prognosis.

Hypoxia is a common cause of reduced tumor response to treatment such as irradiation. The purpose of this study was to establish a method in a rat model that is clinically applicable to monitor the efficiency of glucose transport to both tumor and normal tissue following the induction of hyperglycemia. Female Fischer 344 rats bearing subcutaneous R3230 rat mammary adenocarcinomas received glucose (1 g/kg in 200 mg/ml Normosol) injected in the femoral vein with an infusion pump at a rate of 0.1 ml/min. Microdialysis sampling was performed on all animals. The perfusion marker Hoechst 33342 was injected intravenously at a dose of 5 mg/kg ten minutes prior to sacrifice. After the last blood sample was collected, the tumor and liver were removed and snap frozen for bioluminescence imaging and the rat was sacrificed. Imaging bioluminescence was performed on cryosections of the tumor and liver of the animal to monitor local metabolite gradients and concentrations of glucose in relation to the perfused vasculature, as determined by injected Hoechst 33342. Microdialysis and bioluminescence show comparable data when monitoring the changes of blood, liver, and tumor glucose concentrations as a result of induced hyperglycemia.

Several non-surgical tumor treatment modalities produce their cytotoxic activity by generating reactive oxygen species (ROS). Anti-oxidative enzymes such as superoxide dismutase (SOD) or exogenously supplied antioxidants may therefore reduce the efficacy of these treatments. The aim of the present study was to analyze the impact of (i) inhibiting SOD using 2-methoxyestradiol (2-ME), or (ii) application of α-tocopherol, on the cellular damage induced by hyperthermia (HT) in experimental tumors. DS-sarcoma cells grew either in culture or as solid tumors subcutaneously implanted in rats. , DS-cells were incubated with 2-ME, and cell proliferation, ROS formation, lipid peroxidation and apoptosis were measured. , DS-sarcomas were treated with a ROS-generating hyperthermia combined with 2-ME or α-tocopherol application.

Inhibition of SOD by 2-ME induced pronounced oxidative injury resulting in reduced proliferation. , ROS-generating hyperthermia led to local tumor control in 23% of the animals. The additional inhibition of SOD by 2-ME increased the control rate by approximately 50%. Application of α-tocopherol was found to have no effect on local tumor control, either in combination with ROS-generating hyperthermia or when 2-ME was additionally applied. Inhibition of SOD during ROS-generating hyperthermia results in pronounced cell injury and an improved local tumor control whereas exogenously applied vitamin E seems not to have an impact on oxidative stress.

Changes in cerebral oxygenation were simultaneously monitored by electric paramagnetic resonance (EPR) oximetry and near-infrared spectroscopy (NIRS). The tissue oxygen tension (t-pO) was measured with an L-band (1.2 GHz) EPR spectrometer with an external loop resonator and the concentration of oxyhemoglobin [HbO] and deoxyhemoglobin [Hb] were measured with a full-spectral NIRS system. Mean cerebral hemoglobin saturation (SmcO) was calculated from the absolute [HbO] and [Hb]. Six adult male rats were implanted with lithium phthalocyanine (LiPc) crystals into the left cerebral cortex. The change in oxygenation of the brain was induced by altering the inspired oxygen fraction (FiO) in air from 0.30 at baseline to 0.0, 0.05, 0.10, and 0.15 for 1, 2, 5, and 5 minutes, respectively, followed by reoxygenation with an FiO = 0.30. Although both t-pO and SmcO values showed a decrease during reduced FiO followed by recovery on reoxygenation, it was found that SmcO recovered more rapidly than t-pO during the recovery phase. The recovery of t-pO is not only related to blood oxygenation, but also to delivery, consumption, and diffusion of oxygen into the tissue from the vascular system. Further studies will be required to determine the exact mechanisms for the delay between the recovery of SmcO and t-pO.

There are many interesting aspects regarding hemorheology and tissue oxygenation in organ transplantation (such as liver, kidney, heart, etc.). The ischemia-reperfusion injury syndrome is a very important problem. Much damage in organs appears to be induced by reperfusion injury syndrome. In fact, not only immunological etiopathogenesis but also biochemically-mediated microcirculation alterations can modulate the organ damage induced by ischemia-reperfusion injury during organ transplantation.

During ischemia-reperfusion injury, xanthine oxidase activity, the increase in oxygen free-radicals, and the activation of neuthrophils are all very important. Platelet activating factor (PAT) and LTB (promoting neuthrophils adhesiveness), activated by the xanthine oxidase-derived oxidants during reperfusion, activates the final postischemia injury. Much research is necessary in order to gain a fuller knowledge of the microcirculation conditions and oxygenation during organ transplantation.

In recent years, with the development of techniques in modern molecular biology, it has become possible to study the genetic basis of carcinogenesis down to the level of DNA sequence. Major advances have been made in our understanding of the genes involved in cell cycle control and descriptions of mutations in those genes. These developments have led to the definition of the role of specific oncogenes and tumour suppressor genes in several cancers, including, for example, colon cancers and some forms of breast cancer. Work reported from our laboratory has led to the identification of a number of candidate genes involved in the development of non-melanotic skin cancers. In this chapter, we attempt to further explain the observed (phenomic) alterations in metabolic pathways associated with oxygen consumption with the changes at the genetic level.

Protein C (PC) is an essential blood factor in the human blood coagulation cascade. PC can help achieve blood hemostasis in many deadly disease conditions such as sepsis, cancer, HIV, etc.; reduced oxygen transport due to blood agglutination within the body can cause tissue death and organ failure as a result of low oxygen transport. Our goal is to produce large quantities of low cost zymogen PC for the treatment and prevention of blood clotting resulting from many disease states, as well as provide an effective therapy for PC deficiency.

Current studies show that Immobilized Metal Affinity Chromatography (IMAC) has high specificity and can be used for difficult separations among homologous proteins at relatively low cost compared to current methods, such as Immunoaffinity Chromatography. Thus, we are investigating the optimization of IMAC for the separation and purification of PC from Cohn fraction IV-I.

Molecular interactions within the chromatography column involve many parameters that include: the use and type of chromatographic gel and buffer solution, the pH, temperature, metal ion, chelator, and the sequence and structure of the protein itself. These parameters all influence the protein’s interaction with the column. Experimental equilibrium isotherms show that PC has primary and secondary binding characteristics, demonstrating that the interaction is not just a simple process of one protein binding to one metal ion. Understanding the thermodynamics of interfacial interaction between proteins and surface-bound Cu is essential to optimizing IMAC for PC purification, as well as for separation of other proteins in general. Hence we are undertaking theoretical and experimental studies of IDA-Cu/PC adsorption. The differences in structures of PC and other critical homologous blood factors are examined using the protein visualization program Cn3D. A better understanding of the interfacial phenomena will help determine the most effective conditions to achieve our goal.