Search results for "Acidosi"
showing 10 items of 104 documents
Tumor microenvironmental physiology and its implications for radiation oncology.
2004
Abstract The microenvironmental physiology of tumors is uniquely different from that of normal tissues. It is characterized, inter alia, by O 2 depletion (hypoxia, anoxia), glucose and energy deprivation, high lactate levels, and extracellular acidosis, parameters that are anisotropically distributed within the tumor mass. This hostile microenvironment is largely dictated by the abnormal tumor vasculature and heterogeneous microcirculation. Hypoxia and other hostile microenvironmental parameters are known to directly or indirectly confer resistance to irradiation leading to treatment failure. Hypoxia directly leads to a reduced "fixation" of radiation-induced DNA damage. Indirect mechanisms…
Chapter 6: Swelling of C6 glioma cells and astrocytes from glutamate, high K+ concentrations or acidosis
1992
Publisher Summary With impaired energy supply, cell swelling results from the failure of Na+/K+-ATPase according to the pump-leak model of cell volume regulation. In a series of in vitro studies, glial cell volume changes during defined and strictly controlled alterations of the extracellular environment in vitro. Experiments were performed with C6 glioma cells and astrocytes from primary culture. The major advantages of using C6 cells are the rapid availability of large cell numbers necessary for reliable flow cytometric volume measurements, and the homogeneous cell size distribution permitting the detection of even subtle volume changes. The sodium-potassium pump was blocked by the cardia…
Diabetes care practices and outcomes in 40.000 children and adolescents with type 1 diabetes from the SWEET registry during the COVID-19 pandemic
2023
Aims This study aimed to provide a global insight into initiatives in type 1 diabetes care driven by the COVID-19 pandemic and associations with glycemic outcomes. Methods An online questionnaire regarding diabetes care before and during the pandemic was sent to all centers (n=97, 66,985 youth with type 1 diabetes) active in the SWEET registry. Eighty-two responded, and 70 (42,798 youth with type 1 diabetes) had available data (from individuals with type 1 diabetes duration >3 months, aged ≤21 years) for all 4 years from 2018 to 2021. Statistical models were adjusted, among others, for technology use. Results Sixty-five centers provided telemedicine during COVID-19. Among those centers naiv…
Remission phase in children diagnosed with type 1 diabetes (T1D) in years 2012-2013 in Silesia, Poland – an observational study
2019
Background/Objective The study aimed to analyze the frequency of partial remission (PR) and its association with chosen clinical and laboratory factors among pediatric patients with newly diagnosed type 1 diabetes (T1D). The long‐term effect of PR on chosen parameters was also investigated. Methods In 194 patients (95 girls) aged 8.1 ± 4.3 years, we analyzed data at T1D onset: glycemia, pH, C‐peptide, antibodies, weight, and concomitant autoimmune diseases. Anthropometric parameters, daily insulin requirement (DIR), and HbA1c 2 and 4 years after T1D diagnosis were also analyzed. We determined PR based on HbA1c and DIR measurements at least every 3 months. Results PR occurred in 59% of patie…
Clinical strategies for the management of intestinal obstruction and pseudo-obstruction. A Delphi Consensus study of SICUT (Società Italiana di Chiru…
2016
Intestinal obstructions/pseudo-obstruction of the small/large bowel are frequent conditions but their management could be challenging. Moreover, a general agreement in this field is currently lacking, thus SICUT Society designed a consensus study aimed to define their optimal workout.The Delphi methodology was used to reach consensus among 47 Italian surgical experts in two study rounds. Consensus was defined as an agreement of 75.0% or greater. Four main topic areas included nosology, diagnosis, management and treatment.A bowel obstruction was defined as an obstacle to the progression of intestinal contents and fluids generally beginning with a sudden onset. The panel identified four major…
Pathophysiological and vascular characteristics of tumours and their importance for hyperthermia: Heterogeneity is the key issue
2010
Tumour blood flow before and during clinically relevant mild hyperthermia exhibits pronounced heterogeneity. Flow changes upon heating are not predictable and are both spatially and temporally highly variable. Flow increases may result in improved heat dissipation to the extent that therapeutically relevant tissue temperatures may not be achieved. This holds especially true for tumours or tumour regions in which flow rates are substantially higher than in the surrounding normal tissues. Changes in tumour oxygenation tend to reflect alterations in blood flow upon hyperthermia. An initial improvement in the oxygenation status, followed by a return to baseline levels (or even a drop to below b…
Concurrent Measurements of O2 Partial Pressures and pH Values in Human Mammary Carcinoma Xenotransplants
1986
Due to severe restrictions of convective and diffusive transport, hypoxic or even anoxic areas exist in malignant tumors. In addition, a high glycolytic rate in tumors both in the presence and absence of oxygen and the insufficient removal of the hereby produced lactic acid lead to an acidification of the tumor tissue. Both hypoxia and acidosis can influence the efficacy of irradiation, chemotherapy and hyperthermia. However, no comprehensive data on the development of both hypoxia and acidosis within the same tumor are available to date. In particular, there is no information regarding human tumors. Therefore, a new model has been developed which allows the systematic evaluation of both pa…
Pathophysiological aspects of hyperthermia
1992
Blood flow in many rapidly growing tumors is sluggish leading to an impairment of convective heat dissipation which facilitates tumor heating compared to normal tissues. In addition, the compromised microcirculation causes a hostile metabolic micromilieu which can modulate the therapeutic effect of heat. After clinically relevant heat doses, a shut-down of tumor microcirculation is often observed creating a “heat-reservoir” and aggravating tumor hypoxia, acidosis, and substrate and energy depletion, factors which are known to greatly enhance tumor cell killing by heat. Since the mechanisms described are mostly derived from experimental results on fast-growing animal tumors, the clinical rel…
Glycemic Outcome Associated With Insulin Pump and Glucose Sensor Use in Children and Adolescents With Type 1 Diabetes. Data From the International Pe…
2021
OBJECTIVE Insulin delivery methods, glucose-monitoring modalities, and related outcomes were examined in a large, international, diverse cohort of children and adolescents with type 1 diabetes from the Better Control in Pediatric and Adolescent Diabetes: Working to Create Centers of Reference (SWEET) -Registry. RESEARCH DESIGN AND METHODS Participants with type 1 diabetes of >= 1 year, aged <= 18 years, and who had documented pump or sensor usage during the period August 2017-July 2019 were stratified into four categories: injections-no sensor (referent); injections + sensor; pump-no sensor; and pump + sensor. HbA(1c) and proportion of patients with diabetic ketoacidosis (DKA) or severe hyp…
Swelling of glial cells in lactacidosis and by glutamate: significance of Cl(-)-transport.
1993
Swelling of glial and nerve cells is characteristic of brain damage in cerebral ischemia or trauma. The therapeutical efficiency of inhibition of Cl(-)-transport by a novel antagonist, the diuretic torasemide, on cytotoxic swelling of glial cells from lactacidosis, or glutamate was analyzed. Lactacidosis and the interstitial accumulation of glutamate are hallmarks of the pathophysiological alterations in ischemic or traumatic brain tissue. C6 glioma cells harvested from culture and suspended in a physiological medium were either exposed to pH 6.2, or 5.0 by lactic acid, or exposed to 1 mM glutamate at normal pH. Cell swelling and viability were quantified by flow cytometry. Lactacidosis of …