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Biomedical subjects

A Ivanov

Publications and source records attributed to A Ivanov.

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

[Anaerobic surgical infection and septic shock].

In the period 1990 through 1995, one-hundred patients operated for acute abdomen or admitted on a routine basis, presenting evidence of anaerobic infection, undergo treatment in the clinic of emergency surgery. Septic shock develops in 10/100 patients (10 per cent). In six of the latter the outcome is fatal--three with infection caused by spore-forming anaerobes (gas gangrene of the inguinal region--of Fournier, and anterior abdominal wall--anus praeternaturalis--two), and three with infection caused by non-spore-forming anaerobes (mixed anaerobic-aerobic infection). Anaerobic surgical infection and septic shock specificity is discussed, with an algorithm of therapeutic approach, based on clinical experience had with 100 patients, being proposed in either of them. Special emphasis is laid on antibiotic prophylaxis against anaerobic surgical infection. Its implementation in the concrete clinical conditions in this country demands a clearcut hospital drug policy (adoption of the "Drug Formularies" system), and elaboration of a new economical approach to the choice of antibacterial agents (using some of the forms of pharmaco-economical analysis, practicable with a view to the Bulgarian health-care model).

Abdomen, Acute↗
PubMed1995

Extranuclear dendrites of locus coeruleus neurons: activation by glutamate and modulation of activity by alpha adrenoceptors.

1. Locus coeruleus (LC) neurons were recorded extracellularly and intracellularly in rat brain slices. Effects of glutamate applied to the area of distal extranuclear LC dendrites, and of alpha-2 adrenoceptors applied in the bath, were determined on activity of these cells. 2. Glutamate applied to the area of distal dendrites potently activated LC neurons. These responses were not blocked by either 1 microM tetrodotoxin or 2 mM Co(2+)-10 mM Mg2+. This indicates that glutamate acting directly on distal dendrites can potently activate LC neurons. 3. Bath application of the alpha-2 adrenoceptor antagonists yohimbine (1 microM) or idazoxan (1 microM) significantly increased responses of LC neurons evoked by dendritic glutamate application. These antagonist treatments also transiently decreased, and then increased, spontaneous discharge activity in LC neurons. 4. Alterations in spontaneous and glutamate-evoked activities after blockade of alpha-2 adrenoreceptors were not observed in LC neurons of reserpinized rats. This indicates that the altered LC activity and responsiveness to glutamate following alpha-2 antagonist treatment in nonreserpinized slices are mediated via blockade of effects of endogenously released noradrenaline. 5. The alpha-1 antagonist prazosin (1 microM) caused a small but reliable decrease in the spontaneous firing rate of LC neurons. After prazosin pretreatment, alpha-2 antagonists did not evoke the expected delayed increase in LC spontaneous firing and response to glutamate application. These results indicate that activation of alpha-1 adrenoceptors may contribute to the delayed increase in excitability of LC neurons after alpha-2 antagonist administration. The possible roles of alpha-1 and alpha-2 adrenoreceptors in regulation of spontaneous discharge rate and glutamate-evoked responses in LC neurons are discussed.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed1995

[The determination of plasma malondialdehyde in patients with obstruction of the small intestine].

Plasma malonic dialdehyde (MDA) level is evaluated in 22 patients with small intestinal obstruction. Bowel strangulation is found in 14 cases-reversible in eight, and irreversible in six, and simple small-intestine obstruction-in eight. The plasma MDA level in this group of patients is compared with the one in a control group of twenty healthy individuals. In the control group MDA is 2.6 +/- 0.5 nmol/ml, in strangulation obstruction-6.9 +/- 1.5 nmol/ml, and in those with simple obstruction-2.8 +/- 0.4 nmol/ml. The difference in MDA level between strangulation cases and the other groups under study is statistically significant plasma MDA increase in patients with small intestinal strangulation may be successfully used for the purpose of diagnosis.

Adult↗
PubMed1995

[Design, management and handling of a randomized trial].

Before a newly developed treatment starts being used in practice it must pass through three clinical trial steps, called phase I, II, and III. The subject of this presentation are the phase III clinical trials. Their goal is to compare the treatment under study to the currently standard treatment (either to show the superiority of the new treatment, either to show it is equivalent in terms of efficacy with the standard one). The only way of ensuring a valid comparison is to perform a randomised clinical trial, meaning that for each patient the treatment is assigned randomly by a mechanism unknown by the investigator(s). Each clinical trial must start with the creation of a protocol. The protocol is a document that describes in details all the aspects of performing the trial. Normally, once the first patient is registered into the trial, the protocol shouldn't be modified any more. That's why it must foresee every problem that might show up during the trial, which makes it a difficult task. A crucial question which has to be answered before the trial begins is the 'sample size'--the number of patients needed. This number is based on several parameter. A bad choice of one of these parameters can completely compromise a trial. All data handling and administrative tasks are usually handled by data managers. They have a crucial role in collecting and validating all the data, and the quality of the whole clinical trial is closely related to the quality of their work. To help them in their tasks, a suitable computer system can be of invaluable help. One of the last steps of the trial is the statistical analysis itself. The statistical tests to be used must be predefined in the protocol and depend mainly on the end points used for assessing the efficacy. To avoid all bias the analyses must be done using the 'intent to treat' principle. Many problems can show up during the trial: ineligible patients or lost to follow up, protocol violations, etc. A well written and well respected protocol should help reducing this list to a minimum. Finally, all this work will only be useful if the results are widely presented in a clear and pertinent way. If the medical community is not convinced by the results, all those resources would have been wasted.

Bias↗
PubMed1994

[MRT in nonpalpable testes].

Magnetic resonance imaging was performed in 22 male patients for localisation of 27 nonpalpable undescended testes. The operative verification, carried out in 19 testes (15 patients) served as basis for checking on the accuracy of MRI results and for their comparison with those of sonography and laparoscopy. The impalpable testis was localised via MRI in 13 cases and its lack was correctly established in three cases. There were three false MRI diagnoses. The suspicion of two intraabdominal localised testes were not confirmed at surgery and one intracanalicular testes were not seen by MRI. The low signal intensity of the undescended testes on T2-weighted images is indicative for fibrotic changes and may be of value for more accurate planning of the operative volume. MRI offers a new promising opportunity for localisation and morphologic estimation of the undescended testis and should be performed before the invasive investigation methods.

Adolescent↗
PubMed1994

[Our experience with treating acute noncalculous cholecystitis].

Based on a comprehensive literature survey, personal experience with the management of 89 patients, presenting acute noncalculous cholecystitis, is shared. All patients are clinically observed in the acute phase of the disease. In 60 cases the latter becomes manifest with recurrent attacks, and in 29 there are no previous signs or symptoms of biliary diseases. Diagnosis is made on the ground of active echographic and clinical observation. Conservative therapy is effective in 28 cases. The remainder (61) are operated at 1 to 4-day intervals after the onset of the disease because of persisting symptomatology and/or deterioration of the patient's condition. During laparotomy the gallbladder presents marked enlargement with thickened, exudate-imbibed wall. Cholecystectomy is done in all 61 cases. In twelve of them, owing to dilatation of the common bile duct and minimal serum bilirubin increase, stenosing papillitis is diagnosed by intraoperative cholangiography, treated by external biliary drainage and endoscopic sphincterotomy, undertaken after improvement of the general condition. Acute inflammation, free of fibrosis, with isolated foci of gangrene and necrosis of the bladder wall are histologically documented. In four senile patients presenting serious concomitant diseases, with exceptionally high operative risk, echographic percutaneous transhepatic cholecystectomy is resorted to, followed by antibiotic bladder instillations with a very good outcome. The summed up results of acute noncalculous cholecystitis treatment are estimated as very good.

Acute Disease↗
PubMed1994

[The treatment of acute cholecystitis complicated by mechanical jaundice].

After analyzing the summed up treatment results in 368 patients with acute cholecystitis, complicated by obstructive jaundice, the inference is reached that it is a matter of a complication, unfavourable in terms of prognosis, with a definite impact on both immediate and long-term therapeutic results. Early operative intervention following intensive preoperative preparation (including ERHPG with endoscopic papillosphincterotomy and ensuing biliary decompression, or echographic percutaneous cholecystectomy) contribute to control the acute inflammatory process in the gallbladder, and preclude the development of liver (or hepato-renal) failure against the background of obstructive jaundice. Proceeding from the severe, irreversible changes in liver and kidney, hardly responding to treatment, and persisting deterioration of the general condition, acute cholecystitis complicated by obstructive jaundice is defined as an emergency life-endangering condition, requiring a priority operative approach.

Acute Disease↗
PubMed1993

Common acute lymphoblastic leukemia antigen expression on visceral epithelial cells in several types of glomerulonephritis.

The distribution of a group of glomerular antigens and the composition of deposits was examined by immunoelectron microscopy in patients with idiopathic membranous nephropathy (MN), focal segmental glomerulosclerosis (FSG) and membranoproliferative glomerulonephritis (MPGN). The decrease in expression of common acute lymphoblastic leukemia antigen (CALLA) on glomerular visceral epithelial cells was found in MN and FSG. The loss of CALLA on visceral epithelial cells was typical for immature glomerulus and for this cell culture. On the strength of these results we can suppose that the dedifferentiation of visceral epithelial cells takes place in MN and FSG. It leads to changes in the synthesis of the glomerular basement membrane components.

Antigen-Antibody Complex↗
PubMed1993

[MRT in clinically unclear posttraumatic knee joint lesions].

An MRI examination was performed on 31 patients with clinically questionable posttraumatic knee joint lesions. A broad range of intra- und extraarticular pathological changes was found. The correlation of MRI with arthroscopy and surgery showed a correct MRI diagnosis in 78% of the meniscal lesions (n = 18) and in 89% of the anterior cruciate ligament ruptures (n = 9). An analysis of false positive and false negative MRI diagnoses was made. MRI offers the opportunity for noninvasive complex assessment of knee joint structures and is of particular value in the diagnosis of posttraumatic knee joint lesions.

Adolescent↗
PubMed1993

[Biliary ileus].

This is a report on nine cases presenting biliary ileus. All patients undergo operative management. Two female patients present Bouveret's syndrome. The inference is reached that gallstone induced intestinal obstruction is characterized by atypical clinical patterns, conditioning in turn the diagnostic difficulties encountered, and the necessity to undertake operative treatment against the background of advanced ileus. The latter is one of the rarest forms of intestinal obstruction. Biliary ileus treatment consists in the removal of small intestinal impatency. The concretion is pushed in oral direction, and its evacuation is successfully accomplished by enterotomy, duodenotomy or gastrotomy. Two fatal outcomes due to severe advanced form of ileus are reported.

Aged↗
PubMed1993

[Acute rectal hemorrhage].

Problems of the diagnosis, tactics and treatment of acute rectal hemorrhage are discussed. A diagnostic-tactical plan for determining the cause, source, localization and degree of bleeding are discussed. A diagnostic-tactical plan for determining the cause, source, localization and degree of bleeding, the acquired temporary or definitive hemostasis and the degree of blood loss is presented. Adequate approach to acute rectal hemorrhage helps to shorten the operation time, to reduce the extent of preoperative resuscitation and decrease total and operative lethality.

Acute Disease↗
PubMed1993

Phosphatidylcholine-specific phospholipase C from Achromobacter xylosoxidans.

A new phosphatidylcholine-specific phospholipase C (EC 3.1.4.3.) has been isolated from the culture broth of Achromobacter xylosoxidans. Growth conditions were optimized for maximum production of the enzyme. A temperature-sensitive synthesis was established. Chromatography on CM Sephadex and polyacrylamide gel electrophoresis of the native enzyme revealed a number of isozymes. The water soluble substrate for phospholipase p-nitrophenylphosphorylcholine was not hydrolysed by the enzyme.

Alcaligenes↗
PubMed1992

Effect of phosphatidylinositol-specific phospholipase C from Bacillus thuringiensis on solid spinocellular carcinoma.

Phosphatidylinositol-specific phospholipase C (PIPLC) from Bacillus thuringiensis (0.11 units per ml) inhibited growth of IC-Sofia carcinoma cell line in culture by 64%. The growth of transplanted carcinoma in hamsters was also inhibited by 29% at a dose of 4.9 units of PIPLC/kg animal/day. In addition, degeneration processes and a significant fibrosis of the tumour occurred. The functional, clinical, biochemical and haematological parameters studied were consistent with the established antitumour effect in vivo.

Animals↗
PubMed1992

Treatment of advanced bladder cancer by submucosal injection of methotrexate in the anorectal area.

In 1988, Shafik et al. presented their first attempt to apply cytostatics in the treatment of pelvic malignancies. Experimentally and clinically, they studied the anal route for administration of methotrexate, and their first results showed that higher concentration of drugs can be achieved in the bladder wall compared to that in serum. Since December 1988, we have been engaged in experimental and clinical investigations of the possibilities this method might reveal. Experiments with animals have proven that submucosal injection of the cytostatic agent does not induce local changes. The clinical trial on 20 patients with tumors of stage T2-T4 has not shown side effects, either local or systemic. The treatment was well tolerated by the patients. Anorexia has been reported in 3, elevated temperature in 2 and leukopenia in 4 of 20 patients. Complete response has been documented in 3 (15%), partial response in 3 (15%), stabilization in 5 (25%) and progression of the disease in 9 (45%) of the patients. Mean duration of remissions was 10.3 months (range 9-12). The distribution of submucously injected contrast medium into the anorectal area has been studied by computerized tomography in 4 of the patients. Although our results do not support the original estimates of the inventors of the method, its ease of application, the possibility of out-patient administration and negligible side effects are sufficient arguments for performing further experimental and clinical studies.

Administration, Rectal↗
PubMed1991

Purification and some properties of phospholipase C from Achromobacter xylosoxidans.

A non-haemolytic phospholipase C (EC 3.1.4.3) was purified from the culture medium of Achromobacter xylosoxidans with a 5% yield and a purification factor of 330. A combination of ultrafiltration, acetone precipitation and two subsequent affinity chromatographic steps was used. The affinity chromatography is a new application of 2-(4-aminophenylsulphonyl)ethyl-cellulose, a sorbent that has previously been used for the purification of phospholipase C from Bacillus cereus. The purified enzyme gave four distinct bands on polyacrylamide gel electrophoresis, and each band was catalytically active. Under our experimental conditions, the phospholipids examined were hydrolysed in the following order: phosphatidylcholine, phosphatidylethanolamine, sphingomyelin. Neither the synthetic substrate p-nitrophenylphosphorylcholine nor phosphatidylinositol was hydrolysed under different experimental conditions. For maximal hydrolytic activity toward phosphatidylcholine, the enzyme required Triton X-100 and Ca2+ ions. EDTA was inhibitory, but the enzyme activity was almost completely restored by Zn2+. The molecular mass of the phospholipase C, estimated by gel permeation, was 34,000 daltons.

Alcaligenes↗