Sleep related O2 desaturation in COPD patients with normoxaemia and mild hypoxyaemia

It is unknown whether daytime features predict oxygenation during sleep in COPD patients with normoxaemia or mild hypoxaemia. In this study our purpose was to evaluate by a pulse oxymeter, nocturnal desaturation in 33 COPD with PaO2 > 60 mmHg and to examine some daytime parameters as possible predictors of nocturnal hypoxaemia. A significant nocturnal desaturation has been defined by spending > or = 30% of total sleep-time with a TSTSaO2 < 90% > 30. According to this criterion we classified our patients in Desaturators (D) and Non Desaturators (ND). Our results showed that 39% of our patients were D and 61% ND. Among anthropometric and respiratory functional data we found that daytime SaO2B (r = 0.74 p < 0.001) daytime PaO2 (r = 0.47 p < 0.01) and daytime PaCO2 (r = 0.45 p < 0.05) were significantly correlated with the nocturnal oxygen desaturation and can predict the presence of sleep related hypoxaemia. In conclusion, our study confirms that a relatively high percentage of COPD patients with normoxaemia or borderline hypoxaemia exhibits significant nocturnal hypoxaemia. Further studies will suggest whether sleep related hypoxaemia deserves nocturnal oxygen therapy.     

A topical metabolic inhibitor to improve transcutaneous estimation of arterial oxygen tension in adults

The use of Eugenol as a contact medium in the measurement of transcutaneous oxygen (tcPO₂) partially inhibits the metabolism in the underlying tissue, thereby reducing oxygen consumption and increasing tcPO₂. Oxygen consumption in the tissue can be estimated from the rate at which tcPO₂ falls when blood flow is occluded, and blood flow in the tissue can be estimated from the rate at which tcPO₂ increases when the subject changes from breathing air to pure oxygen. Both these measurements have been made with Eugenol and distilled water as contact media. From these measurements it has proved possible to estimate the arterial oxygen tension (aPO₂) of healthy adults at a relatively low sensor temperature (43°C).     

Spectral-fluorescent characteristics of rat transcortin in normal conditions and during experimental circulatory insufficiency

Spectral-fluorescent parameters of rat transcortin isolated from blood plasma of intact rats and rats with circulatory insufficiency were studied. The differences in the Schtern Folmer constants and the dissociation constants for the transcortin-corticosterone complex obtained during the protein titration by corticosterone may be due to different tryptophanyl surroundings in the molecules of the studied proteins. This may be a consequence of the conformational rearrangements of the corticosteroid-binding globulin molecules.     

State of methaemoglobin in normal adults and in patients with hereditary methaemoglobinaemia.

The predominance of valency hybrids over fully oxidized methaemoglobin in the haemolysate from a methaemoglobinaemia patient can be explained by random oxidation of the haems, followed by re-assortment and co-migration of equally charged alpha beta-dimers in the electric field of the isoelectric-focusing gel.     

Relation of CuZnSOD activity with renal insufficiency in hypertensive diabetic patients

Diabetes and renal insufficiency are interrelated metabolic disorders closely associated with redox homeostasis disturbances. The aim of this study was to compare the activity of copper zinc superoxide dismutase (CuZnSOD) in the erythrocytes of hypertensive diabetic patients with or without renal insufficiency with normal healthy control subjects. In both groups of diabetic patients, blood glucose level and the content of glycosylated hemoglobin (HbA1c) were higher than in the control group. However, CuZnSOD activity was significantly higher than control only in hypertensive diabetic patients with renal insufficiency. Our results suggest that disturbances in superoxide homeostasis do correlate with long-term complication in diabetes, i.e. diabetic renal insufficiency and hypertension.     

Estimation of the functional role of arterial pathways to the buttock circulation during treadmill walking in patients with claudication.

The aim of the study was to estimate the functional contribution of the arterial inflow pathways to the pelvic circulation during walking in patients with stage 2 lower extremity arterial disease. Transcutaneous oxygen pressure (Ptc(O(2))) changes during exercise can be used to estimate the severity of regional blood flow impairment while walking. Seventy patients with stable lower limb claudication were studied using a multivariate linear regression model. The relationship between exercise-induced buttock Ptc(O(2)) changes, the ipsilateral calf Ptc(O(2)) changes, and the arterial diameters of the pelvic arteriographic pathways were analyzed. The ipsilateral hypogastric and lumbar pathway, as well as the ipsilateral calf Ptc(O(2)) changes, were the only variables significantly related to buttock Ptc(O(2)) changes (r = 0.47; P < 0.001). Their normalized respective contribution to the regressive model was 39%, 19%, and 18%. None of the contralateral hypogastric, mesenteric, and sacral pathways or pathways stemming from the external iliac artery showed significant correlation to buttock Ptc(O(2)) changes. The ipsilateral hypogastric and ipsilateral lumbar pathways are the major pathways responsible for the functional buttock blood flow supply during walking. The role of contralateral hypogastric, inferior mesenteric, and median sacral pathways and arteries distal to the internal iliac trunk is negligible in the normal or compensatory blood flow supply. Distal Ptc(O(2)) decrease at exercise aggravates proximal Ptc(O(2)) decrease, possibly through the occurrence of a "steal phenomenon" of distal over proximal circulation during walking.     

Association of blood proteins with large unilamellar liposomes in vivo. Relation to circulation lifetimes.

The proteins associated with liposomes in the circulation of mice were analyzed in order to determine whether bound proteins significantly influence the fate of liposomes in vivo. Liposomes were administered intravenously via the dorsal tail vein of CD1 mice and were isolated from blood after 2 min in the absence of coagulation inhibitors using a rapid "spin column" procedure. Various negatively charged liposomes exhibiting markedly different clearance properties were studied; notably, these included liposomes containing 10 mol % ganglioside GM1 which has been previously shown to effectively limit liposomal uptake by the fixed macrophages of the reticuloendothelial system. The protein binding ability (PB; g of protein/mol of lipid) of the liposomes was quantitated and related to the circulation half-life (tau 1/2) of the liposomes. Liposomes having similar membrane surface charge imparted by different anionic phospholipids were found to exhibit markedly different protein binding potentials. Furthermore, PB values determined from the in vivo experiments were found to be inversely related to circulation half-lives. PB values in excess of 50 g of protein/mol of lipid were observed for rapidly cleared liposomes such as those containing cardiolipin or phosphatidic acid (tau 1/2 less than 2 min). PB values for ganglioside GM1-containing liposomes (tau 1/2 greater than 2 h) were significantly less (PB less than 15 g of total protein/mol of total lipid). PB values were also determined for liposomes recovered from in vitro incubations with isolated human serum; relative PB values obtained from these in vitro experiments were in agreement with relative PB values measured from in vivo experiments. PB values, therefore, could be a useful parameter for predicting the clearance behavior of liposomes in the circulation. Liposomes exhibiting increased PB values in vivo were shown by immunoblot analysis to bind more immune opsonins, leading to a higher probability of phagocytic uptake. Finally, based on results obtained using the in vitro system, it is suggested that the mechanism by which ganglioside GM1 prolongs the murine circulation half-life of liposomes is by reducing the total amount of blood protein bound to the liposomes in a relatively nonspecific manner.     

Blood leukocyte responses to extracorporal circulation. III. Long term extracorporeal circulation without and with irradiation in normal and splenectomized dogs

Long term (12-48 h) extracorporeal circulation without and with irradiation of the blood was performed in normal and splenectomized dogs in order to observe the effect of these procedures on blood leukocyte counts including CFU-C. A transient granulocytopenia and a decrease of lymphocyte count were observed. The blood CFU-C level diminished to a very low level and remained low for the whole time of the experiments. There was no significant difference between the results of procedures with or without irradiation. The similar effect of a shortened tubing system on the blood leukocyte count is also reported. Heparin infusion alone did not decrease the peripheral CFU-C concentration. The possible explanations for the observed phenomena are discussed.     

Electrical activity of the triceps surale muscle under static load in patients with chronic peripheral circulatory insufficiency

Combinations of various types of dynamics of integrated synchronously recorded bioelectrical activity of the gastrocnemius (lateral and medial) and soleus muscles were analyzed in healthy test subjects and patients with occlusive diseases of vessels of the lower limbs (obliterating endarteritis and atherosclerosis), who performed static work “to capacity”, maintaining a load of 50% of the maximum force of the muscles (plantar flexors of the sole of the foot). The frequency analysis of the elicited types of changes in the electromyogram integrals and their combinations testifies to general regularities in the functional organization of voluntary organization of an effort when fatigue develops in test subjects of two groups, and some features in the conjugate activity of the muscles ascribed to the group of the so-called “principal synergists,” recorded only in the patient group.     

Relation of pressure and flow of pulmonary circulation in patients with chronic obstructive pulmonary disease

A series of 31 patients with various degrees of chronic obstructive pulmonary disease underwent right heart catheterization using flow-directed thermodilution catheters. Both rest and supine exercise values were obtained. The patients were divided into two groups on the basis of their reduction in forced expiratory volume in 1 s (FEV1). In patients with FEV1 values of greater than or equal to 1,300 ml (group 1), the arterial oxygen partial pressure (PaO2) did not significantly change with exercise, while in patients with FEV1 of less than or equal to 1,200 ml (group 2) PaO2 significantly (p less than 0.05) fell in response to exercise. In group 2, a significant increase of total pulmonary resistance (TPR) with exercise was found (p less than 0.01). Pulmonary vascular resistance (PVR) remained unchanged in both subgroups. It is suggested that the value of PVR for subgroup 2 is artificially low because an important variable, namely pulmonary artery wedge pressure, is influenced by alveolar pressure in patients with an uneven distribution of perfusion and ventilation at pulmonary venous pressures lower than alveolar pressure. The steeper slope of the pressure-flow relationship in these patients is probably due to an increased vascular tone caused by chronic hypoxia at rest and further fall of PaO2 and rise of arterial CO2 partial pressure in response to exercise.