PubMed Health⌕ Search

Biomedical subjects

D Petkov

Publications and source records attributed to D Petkov.

At least 37 records · Page 2Linked to original sources
PubMed1988

[Outpatient echographic follow-up of patients with Fraley's syndrome].

The follow-up of the degree and evolution of the upper hydrocalicosis and of the parenchymatous changes in patients with Fraley's syndrome is very important. All authors agree that these patients should be followed up periodically. 20 patients with Fraley's syndrome were followed up and the authors conclude that the echographic examination is a very reliable method for prophylactic medical examinations since it is informative, harmless and economically advantageous.

Adult↗
PubMed1988

[Computed tomography in cholestasis].

116 patients with jaundice were examined by computer tomography. In 92.3% of the patients examined the computer tomography gave correct information for the etiology of the jaundice: in 36 patients (31%) obstructive jaundice was established; in 71 patients (61.3%) the jaundice was nonobstructive and in 9 patients (7.7%) the etiology was not established. The characteristics of the CT findings in obstructive and nonobstructive jaundice are discussed. The causes of the diagnostic mistakes in CT examinations of patients with jaundice are also discussed.

Cholecystography↗
PubMed1987

[Potentials and limits of ultrasonic diagnosis in gastroenterology].

The great diagnostic value of ultrasonic tomography in the diagnosis of liver, biliary, pancreatic, gastric, intestinal, abdominal and retroperitoneal disease is reviewed and proved. Best results can be achieved in the indications for its application and the potentialities of the method are well known. The sonographic results should always be assessed with the clinical, laboratory and other instrumental data. The faulty diagnoses are due not to the method itself but to the incompetent interpretation of the sonographic images and to the lack of knowledge for the scope and limitations of sonography.

Gallbladder Diseases↗
PubMed1987

[Arterial stenosis in kidney transplant patients].

A short literary review is presented on the frequency and characteristics of the stenosis of the arterial anastomosis or of sections next to it in patients with transplanted kidney. The histories of three patients are reported. In two of the patients in the 6th and 7th month following the transplantation a severe arterial pressure appeared and a systolic murmur could be heard medially from the transplanted kidney. By renal vasography a marked stenosis of the anastomosis of the renal artery with the hypogastric artery was found. The stenosis was not corrected in time which led to its thrombosis and explantation of the kidney. In the third patient the renal vasography did not reveal stenosis of the anastomosis. In this case the symptoms were due to a chronic crisis of rejection of vasal type. The appearance of severe persistent arterial hypertension 6-7 months after a kidney transplantation is a signal for possible stenosis of the arterial anastomosis which requires timely examination and surgical correction if found.

Adult↗
PubMed1987

[Diagnostic potentials of computed tomography in focal liver diseases].

98 patients with focal liver diseases were examined by computer tomography: 29 patients with primary liver cancer, 44 patients with liver metastases, 16 patients with liver cysts, 4 patients with hemangioma and 5 patients with liver abscess. In 92.9% of the patients examined the computer tomographic examination gave accurate information about the focal liver disease. Only in 7 patients (7.1%) the examination failed. The characteristics of the liver changes found by computer tomography in primary liver cancer, liver metastases, cysts, hemangioma and liver abscess are discussed as well as the factors for the failure of the examination.

Carcinoma↗
PubMed1987

[Treatment of hepatic and pulmonary echinococcosis with mebendazole (Vermox)].

The therapeutic efficacy of Mebendazole (Vermox) was studied in 13 patients: 8 with liver and 5 with pulmonary echinococcosis. The drug was given in a dose of 50-70 mg/kg body mass. Good therapeutic effect was found in 4 patients (2 with liver nad 2 with pulmonary echinococcosis), partial therapeutic efficiency was registered also in 4 patients (2 with liver and 2 with pulmonary echinococcosis) and failure in 5 patients. The drug was more effective in pulmonary echinococcosis, in younger and smaller cysts than in older cysts with thick walls and presence of filial cysts. The efficacy of the treatment is related to the drug plasma concentration but the results depend on the cysts condition, too. The careful examination of the patients--X-ray, ultrasonography and computer tomography--before, during and after the treatment ensures objective evaluation of the treatment results.

Adult↗
PubMed1984

[Computed tomography and echography in chronic pancreatitis and pancreatic carcinoma].

The diagnostic possibilities of computer tomography and echographic investigations were studied in 58 patients with chronic pancreatitis and 36 patients with carcinoma of pancreas. Positive morphological signs for the existence of chronic pancreatitis were established in 75,9 per cent in computer tomography and in 83,93 per cent in echographic investigations. The difference in the diagnostic sensitivity of both diagnostic methods is not significant (p greater than 0,05). The calcifications in pancreas are better detected by computer tomography whereas both methods are equivalent in the diagnosis of the pancreatic cystes. In carcinoma of pancreas computer tomography gives the correct diagnosis of the disease (p greater than 0,05) in 69,5 per cent and echography--in 78,8 per cent of the patients. With computer tomography false negative results amount to 30,5%; in 13,9 per cent normal pancreas was described and in 16 per cent--pseudocyst in pancreas. With echography--false negative results were established in 21,2 per cent of the patients; 12,1 per cent chronic pancreatitis was described, in 9,1 per cent--pseudocyst in pancreas but, at the same time, pancreas was not properly visualized in 8,3 per cent of the examined. Making use of both methods, accurate diagnosis was made in 83,3 per cent of the patients with carcinoma of pancreas.

Carcinoma↗
PubMed1983

[The value of computerized tomography for the diagnosis of diabetic osteoarthropathy].

The diagnostic possibilities of computed tomography as compared to conventional radiology are presented. Morphological changes, which can be identified by normal x-rays, can be shown by computed tomography without any disturbing overshadowing. The computed tomography is showing especially well necrotic lesions, pathological fractures, and joint changes. The high resolution of computed tomography reveals good visibility of the adjacent soft tissues and para-articular structures. As computed tomography gives additional and important informations, it should be used for solution of diagnostic problems in diabetic osteoarthropathy.

Adult↗
PubMed1978

Catalysis and leaving group binding in anilide hydrolysis by chymotrypsin.

The influence of the leaving group on the reactivity of specific anilides in alpha-chymotrypsin-catalyzed hydrolysis (chymotrypsin, EC 3.4.21.2) involves both its binding to the enzyme (steric effect) and electronic nature (electronic effect). These effects are considered in terms of the stereoelectronic theory for the formation and cleavage of the tetrahedral intermediate in acyltransfer reactions. The application of this theory to the enzyme hydrolysis leads to the conclusion that the nature of the reaction products and the effectiveness of the catalysis are controlled by the orientation of the leaving group nitrogen lone pair orbital. The leaving group binding affects the formation of a reactive conformation of the enzyme tetrahedral intermediate that is presumed to intervene between the Michaelis complex and the acylenzyme. The steric and electronic effects could be separated in a straightforward fashion only in the case of equal binding of the leaving groups to the leaving-group-binding site of alpha-chymotrypsin.

Anilides↗
PubMed1975

Structure-activity relationship in the urokinase hydrolysis of alpha-N-acetyl-L-lysine anilides.

The absence of both nonproductive binding and substrate activation and also the good solubility of the substrates make the urokinase-catalysed hydrolysis of specific anilides a very suitable reaction for substrate structure-enzyme activity studies. Derivatives of alpha-N-acetyl-L-lysine anilide with high sigma minus-value substituents in the aniline ring were synthesized. Rate constants kappa-cat. and apparent Michaelis-Menten constants K-m (app.) are presented. From the substituent dependence of kappa-cat. and from the fact that kappa-cat. is 13 to 37 times smaller than the deacylation rate constant it is concluded that the rate-limiting step proceeds prior to deacylation. The catalytic rate constant kappa-cat. obeys a linear free-energy relationship of the Hammett type with Q equals +0.72. Two different mechanisms implied by the results obtained from the model reaction (specific base and general acid-base catalysed hydrolysis of N-acetylglycine anilides under extreme conditions) are proposed in order to account for this positive and low Q-value. In the first mechanism the breakdown of an enzyme tetrahedral intermediate is rate-limiting, while in the second one its formation controls the overall rate. The discrimination between the two mechanisms, however, could not be found.

Anilides↗