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Biomedical subjects

A Somogyi

Publications and source records attributed to A Somogyi.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Experimental models in research of the pathomechanism of diabetes mellitus].

The authors review the knowledge accumulated on animal models of diabetes during the last decade. The most commonly used diabetes models and the underlying disease processes are summarized, respectively. The best known diabetogenic substances, Streptozotocin and Alloxan are described, including their usage, dosage dosing intervals, and mechanism of action. The latest results are included in the article which discuss the possible role of free radical-induced injury of beta cells in Streptozotocin and Alloxan diabetes.

Alloxan↗
PubMed1996

[Emergency coronary revascularization using various arteries].

Authors present the case report of a young man with advanced coronary artery disease of the left main trunk and the big branches of the left coronary system leading to sudden onset of many ventricular fibrillations associated with unconsciousness requiring several reanimations. The condition was treated with coronary artery surgery with the usage of three different arterial conduits (right radial artery, right gastroepiploic artery as free grafts and the left internal mammary artery in situ) with an additional saphenous vein bypass graft. Details of surgical procedures as well as the documents of the early postoperative course and of the 1 month follow up are given.

Adult↗
PubMed1996

[Free radical reactions in juvenile rats treated with streptozotocin].

Male, weaned Wistar albino rats (n = 8) were treated by single dose of intravenous 50 mg/bodyweight-kg streptozotocin (STZ) injection. Changes in carbohydrate and lipid metabolism, and scavenger capacity of red blood cells and liver homogenates were evaluated and compared to the respective values of the control group (n = 9) after 3 weeks. HbAlc was significantly higher (p < 0.005) in the STZ treated group. Plasma triglyceride also showed a marked elevation compared to the control group (p < 0.05). Scavenger capacity in erythrocytes was significantly (p < 0.05) higher in treated animals while no change was observed in liver homogenates. No alteration was observed in the superoxide dismutase activity of treated animals, but catalase activity was weaker (p < 0.05). Thiobarbituric acid reactive substances were in higher concentration in plasma of STZ treated animals (p < 0.01) and were in comparable amount in homogenates. The results suggest that 3 weeks after STZ treatment of rats, alterations can be observed in the scavenger system and of the examined tissues changes are most prominent in erythrocytes.

Animals↗
PubMed1996

Surface-induced dissociation: an effective tool to probe structure, energetics and fragmentation mechanisms of protonated peptides.

The utility of surface-induced dissociation (SID) to probe the structure, energetics and fragmentation mechanisms of protonated peptides is discussed and demonstrated. High internal energy deposition provided by low-energy (eV range) ion-surface collisions yields extensive fragmentation of protonated peptides, allowing relatively uncomplicated and rapid sequence analysis of oligopeptides. SID of multiply protonated peptides is illustrated for peptides with molecular mass of up to approximately 5000 u. It is also illustrated that SID combined with electrospray ionization (ESI) provides a distinctive experimental technique to determine the energetics and mechanisms of peptide fragmentation. The relative position of ESI/SID fragmentation efficiency curves (plots of percentage fragmentation vs. laboratory collision energy) for peptides can be utilized to estimate relative energetics of peptide fragmentation and even to predict proton localization sites. The observed trends support the essential role of the mobile proton model in understanding peptide fragmentation by low-energy tandem mass spectrometry.

Amino Acid Sequence↗
PubMed1996

Effect of alkyl substitution at the amide nitrogen on amide bond cleavage: electrospray ionization/surface-induced dissociation fragmentation of substance P and two alkylated analogs.

Doubly protonated substance P and two analogs alkylated at the ninth position was studied to determine the effect of N-alkylation of the amide nitrogen on the electrospray ionization/surface-induced dissociation (ESI/SID) fragmentation pattern. Thermal decomposition experiments and ab initio calculations were also used in conjunction with the ESI/SID experiments. The increase in relative abundances of the product ions resulting from the cleavage of the amide bond at the alkylation site (relative to the corresponding cleavage for substance P) can be explained by the increased basicity of the amide nitrogen in the context of the 'mobile proton' model. The relative abundances of singly charged b ions suggest a rearrangement of the amide hydrogen located N-terminal to the bond cleaved.

Alkylation↗
PubMed1996

Average activation energies of low-energy fragmentation processes of protonated peptides determined by a new approach.

An attempt was made to estimate the average activation energies of low-energy fragmentation processes of protonated oligopeptides by combining RRKM theory and the results of electrospray ionization/surface induced dissociation (ESI/SID). The average internal energy was assumed to be deposited by three processes: thermal energy gained in the heated capillary of the electrospray source, energy gain in the capillary-skimmer region of the electrospray source, and energy deposition by collision with the surface. The latter fraction was calculated based on the position of the ESI/SID fragmentation of efficiency curves and the ratio of kinetic to internal energy conversion in SID. Using the average internal energy estimated from the experimental results, the average activation energies were evaluated by applying RRKM theory. The application of this approach for protonated leucine enkephalin resulted in an average activation energy of 36 +/- 5 kcal/mol for the lowest energy decompositions. The approach has also been applied to several other peptides in the mass range of 200-1200 Da, yielding average activation energies in the range of 35-47 kcal/mol.

Amino Acid Sequence↗
PubMed1996

Attenuation of morphine-induced delirium in palliative care by substitution with infusion of oxycodone.

We have observed among patients of the Southern Community Hospice Programme that up to 25% experience acute delirium when treated with morphine and improve when the opioid is changed to oxycodone or fentanyl. This study aimed to confirm by a prospective trial that oxycodone produces less delirium than morphine in such patients. Oxycodone was administered by a continuous subcutaneous infusion, as this allowed more flexible and reliable dosing, and patients were monitored for any adverse reactions to the drug. Thirteen patients completed the study. Statistically significant improvements in mental state and nausea and vomiting occurred following a change from morphine to oxycodone. Pain scores improved but did not reach a level of statistical significance. The phenotype status of the patients was tested to establish their capacity to metabolize oxycodone. One patient who did not achieve adequate pain control proved to be a poor metabolizer. These results show that oxycodone administered by the subcutaneous route can provide effective analgesia without significant side effects in patients with morphine-induced delirium. This treatment allows patients to remain more comfortable and lucid in their final days. A small proportion of patients who do not metabolize oxycodone effectively may not receive this benefit.

Aged↗
PubMed1996

Treatment of drug-induced bone marrow suppression with recombinant human granulocyte/monocyte colony stimulating factor.

The haemopoietic growth factors are relatively new additions to the treatment of drug-induced bone marrow suppression. Treatment with growth factors may induce primitive cells to enter into cell cycle. In clinical practice they have beneficial effects on the neutropenia following cytotoxic chemotherapy, bone marrow transplantation, and it may be effective in severe chronic neutropenia by cause drugs. One of the classes of drugs which cause serious agranulocytosis are the antithyroid drugs. A thyrotoxic patient with methimazole-induced agranulocytosis was treated with recombinant human granulocyte-monocyte colony-stimulating factor (rHu GM-CSF). Seven days following treatment with daily subcutaneous injection of 270 micrograms rHu GM-CSF combined with antibiotics and glucocorticosteroids, granulocytes reappeared in the peripheral blood and the sepsis resolved. No side effects of the treatment were observed. The combination of rHu GM-CSF and glucocorticosteroids was successful in restoring normal granulocyte count.

Aged↗
PubMed1995

[Incidence of perioperative myocardial necrosis in the course of coronary bypass surgery].

Authors report an analysis of 101 patients' perioperative data in the view of myocardial necrosis development. Perioperative myocardial infarction is defined as simultaneous detection of new Q wave, and myocardial specific enzyme release with concomitant, transient pump failure. They conclude by the data of patients operated upon, that the quoted criteria were detected simultaneously in 9 patients. Other 7 patients had CK-MB levels of pathological level, but without evidences of any other myocardial infarction criteria. Minimal myocardial mass loss as a sort of terminology is introduced, which is obviously not considered as equal to true myocardial infarction.

Adult↗
PubMed1995

Thermal decomposition kinetics of protonated peptides and peptide dimers, and comparison with surface-induced dissociation.

Rate constants for the unimolecular decomposition of peptide monomer and dimer ions by thermal and surface-induced dissociation (SID) are measured and compared. Rate constants for thermal dissociation are measured in a heated wide-bore capillary flow reactor attached in front of the capillary leading into the mass spectrometer. Thermal decomposition of the leucine enkephalin ion (YGGFL)H+ is observed between 600 and 680 K with rate constants of 20-200 s-1, and yields many of the same fragments as SID at 35 eV, although with different relative intensities. The thermal decomposition yields the Arrhenius parameters Ea = 38.3 kcal/mol, log A = 15.7. The decomposition of the monomer and dimer ions are also observed by using SID on C18 and fluorinated hydrocarbon surfaces, with rate constants of 2 x 10(4) to 40 x 10(4) s-1. The SID activated monomer ions are assigned equivalent temperatures of 710-840 K by extrapolation of the thermal activation parameters. The protonated dimer ion (YGGFL)2 H+ decomposes thermally at 500-540 K to yield the monomer ion. The dimer also decomposes by SID at low collision energies 10-20 eV on both surfaces to yield the monomer ion, and at much higher energies of 60-80 eV to yield fragments identical to the decomposition of the monomer. The large energy requirement for fragmentation from the dimer is due to energy deposition into more degrees of freedom plus the additional energy required for dissociation of the dimer to the monomer.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

[Treatment of methimazole-induced agranulocytosis with granulocyte-macrophage colony stimulating factor].

The authors treated a patient with methimazol (Metothyrin)-induced agranulocytosis with human recombinant granulocyte-macrophage colony stimulating factor (GM-CSF). On day seven, after combined antibiotics, corticosteroid and at a dose of 270 ug daily subcutaneous GM-CSF therapy the septic state of the patients rapidly cured and the leucocytes reached the peripheric blood. No side effects were found. The publication of this case history might help to determine the place of human GM-CSF-s therapy in the treatment of agranulocytosis of different origin.

Administration, Cutaneous↗
PubMed1994

[Hypothetical connection between diabetes mellitus and free radical reactions in arteriosclerosis].

Diabetic patients develop arteriosclerosis at an early age. Their disease progresses more rapidly than that of nondiabetics, due to the underlying cause of arteriosclerosis of which the origin is still unknown. Much attention has been paid recently to the causative role of glycosilated lipoproteins, free radical reactions and hyperinsulinaemia--insulin resistance. Disturbances of the carbohydrate metabolism are accompanied by disorders in lipid metabolism and in the antioxidant system. While proteins undergo glycosilation, free radicals are being released from inflamed cells and, during the course of glycosilation with subsequent lipid peroxidation. Oxidation of lipids and proteins form the basis of pathological processes that might initiate the development of arteriosclerosis. There are attempts to influence the above processes by scavengers--e.g. vitamins, Ca-antagonists, angiotensin converting enzyme inhibitors and antilipaemic agents.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1994

Stable myocardial performance at clamped aorta based solely on the internal mammary artery graft flow: a functional test.

Authors report their experiences with arterial revascularization of the heart using the internal mammary artery (IMA). A method of intraoperative measurement of the free cut end and the effective graft flow of the IMA after meticulous anatomical dissection is described. Free cut end IMA flow was measured both at systemic and extracorporeal pump perfusion pressure and was found as 145+/-26 ml/min and 135+/-16 ml, respectively. A method of measurement of the effective IMA graft flow was introduced and described. An attempt was made to identify factors leading to stable myocardial performance based only on the IMA graft flow just prior to declamping the aorta. The phenomenon is considered as a reliable functional test regarding precise IMA harvesting, anastomosis construction and IMA graft flow capacity.

Adult↗
PubMed1994

The influence of pharmacogenetics on opioid analgesia: studies with codeine and oxycodone in the Sprague-Dawley/Dark Agouti rat model.

In the Sprague-Dawley (SD) rat, the O-demethylation of codeine to morphine is catalyzed by cytochrome P4502D1 (CYP2D1), which is absent in the female Dark Agouti (DA) rat. Oxycodone is similar in structure to codeine but, in contrast, has an analgesic potency in humans similar to morphine. The aim of the study was to test whether the DA rat and the SD rat pretreated with the CYP2D1 inhibitor quinine showed attenuation in analgesia to codeine and oxycodone. With the use of the tail flick model, dose-response curves were constructed to codeine, morphine, oxycodone and oxymorphone (the O-demethylated metabolite of oxycodone) in both rat strains. Codeine did not induce analgesia in the DA rat and there was a 60% reduction in codeine analgesia in the SD rat pretreated with quinine in comparison to the untreated SD rat. In the DA rat, the ED50 to oxycodone was increased 10-fold but there was a significant (P = .0001) prolongation in the duration of analgesia in comparison to that in the untreated SD rat. In the quinine-pretreated SD rat, there was no reduction in oxycodone analgesia but the duration of analgesia was also prolonged. It was concluded that 1) codeine-mediated analgesia requires the formation of morphine through the functional activity of CYP2D1 and 2) oxycodone-mediated analgesia may only be partly dependent on CYP2D1.

Analgesia↗
PubMed1993

[Diabetes mellitus and lipoproteins].

The leading cause of death of diabetic patients is coronary heart disease developing on the basis of accelerated arteriosclerosis. Lipoprotein disorders commonly accompanying diabetes mellitus (DM) promote this process and their joint presence represent cumulated risks for patients. The present review summarizes the various disorders accompanying the two types of DM. In case of insulin-treated, type I, well adjusted DM without signs of primary disturbances of lipid metabolism, quantitative lipid alterations cannot be found. In poorly treated DM with insufficient insulin levels the accumulation of triglyceride particles is due to diminished lipoprotein lipase activity. The main consequence is hyperchylomicronaemia but all three lipoprotein classes are affected. The most characteristic lipid abnormalities in non-insulin-dependent (type II) DM are hypertriglyceridaemia, increased VLDL cholesterol concentration and decreased HDL levels, which frequently remain unchanged even upon the proper treatment of glucose metabolism. The alterations are related to increased free fatty acid levels and decreased glucose uptake resulting from elevated insulin levels. In about one-fourth of cases, primary hyperlipaemia is also present. The treatment of primary and secondary lipid disorders accompanying DM by diet and drugs is of the most uttermost importance.

Diabetes Mellitus, Type 1↗
PubMed1993

Fragmentation of protonated peptides: surface-induced dissociation in conjunction with a quantum mechanical approach.

This paper describes the results of a systematic investigation designed to assess the utility of surface-induced dissociation in the structural analysis of small peptides (500-1800u). A number of different peptides, ranging in mass and amino acid sequence, are fragmented by collision with a surface in a tandem mass spectrometer and the spectra are compared with data obtained by gas-phase collisional activation. The surface-induced dissociation spectra provide ample sequence information for the peptides. Side-chain cleavage ions of type w, which are generally detected upon kiloelectronvolt collisions with gaseous targets but not upon electronvolt collisions with gaseous targets, are detected in the ion-surface collision experiments. A theoretical approach based on MNDO bond order calculations is suggested for the description of peptide fragmentation. This model, supplemented by ab initio calculations, serves as a complement to the experimental work described in the paper and explains (i) the easy cleavage of the amide bond, (ii) charge-remote backbone and side-chain cleavages, and (iii) the influence of intramolecular H-bonding.

Amino Acid Sequence↗
PubMed1993

[Simultaneous surgery for trivalvular and ischemic heart disease as well as calcification of the ascending aorta].

Authors present a case report about the surgical management of trivalvular and ischemic heart disease. The strategy of surgery: venous, arterial revascularisation, valve replacements, valvular plasty is discussed in conjunction with the management of the calcified ascending aorta. The details of the procedure and data of the early follow up period (6 months) are presented.

Aorta↗