Theory of critical enhancement of photorefractive beam coupling.

We develop the idea of critical enhancement of the photorefractive response near the threshold of parametric excitation of space-charge waves (the spatial subharmonics) taking into account the vectorial character of beam coupling and a fairly strong broadening of the nonlinear resonance owing to light absorption. The results of our calculations are a description of the measurable characteristics of critical enhancement and optimization of the experimental conditions for detection of anomalously high amplification gain factors in cubic Bi(12)SiO(20) crystals.

Photorefractive light scattering families in (111)-cut Bi12TiO20 crystals with an external electric ac field.

We investigate here both theoretically and experimentally light-induced scattering in (111)-cut Bi12TiO20 crystals with an external ac field. Our simple analytic solution, which is nearly as precise as the numeric one, allows us to recognize the following otherwise hidden general features. Without the elasto-optic contribution, the scattering patterns are identical for the same value of xi=zeta(0)+(2/3)straight phi(p), where straight phi(p) is the initial polarization angle and zeta(0) is the angle of the external field. With the elasto-optic contribution, the scattering patterns for the same xi are still very similar. For xi not equal0, the scattering patterns depend differently on the elasto-optic coefficients p(12) and p(13) so that in principle p(12) and p(13) can be measured by purely holographic experiments. On the experimental side, we present scattering patterns for xi=0 and +/-30 degrees, showing thereby the similarity of the scattering patterns for equal values of xi. In all cases, we obtain good qualitative agreement of our analytic and numeric calculations with the experimental findings.

Theory of photorefractive vectorial wave coupling in cubic crystals.

We present an analytical theory of vectorial wave coupling in photorefractive cubic crystals which are, in general, optically active. The theory is based on the systematic use of the spatial symmetry properties and the apparatus of the Pauli operators to deal with two-dimensional vectors and matrices. It allows one to give a unified description of a wide spectrum of photorefractive phenomena, including the efficiency and polarization properties of Bragg diffraction, polarization two-beam coupling enhanced by ac fields, the influence of the photoelastic effect, etc. Applications of the theory to crystals of the sillenite family and to particular photorefractive phenomena are given. A good qualitative agreement between the theoretical predictions and experimental data for Bi12TiO20 (BTO) crystals is shown.

Giant momentary readout produced by switching electric fields during two-wave mixing in sillenites.

We show theoretically and experimentally that switching an applied square-wave field produces strong and short pulses of the outgoing signal during two-wave mixing in sillenite crystals. These pulses originate from the strong effect of the field on the optical eigenmodes and can be used in new optical schemes based on time-separated recording and readout processes.

[Oral contraceptive agents and antithrombin III]. / Oralni antikontseptivni sredstva i antitrombin III.

Antithrombin III is one of the most important inhibitors of serine proteases of coagulation and fibrinolysis. It inhibits the activity of thrombin and factor X. Its congenital or acquired reduction leads to an increased risk of thrombosis. In their study the authors aimed to investigate the influence of oral contraceptive preparations--Gravistat and Nonovolan on the activity of antithrombin III. Thirty five women, receiving these drugs for a period of one month to ten years (on the average two and a half years were examined. All women received the drugs in accordance with the physician prescription, taking into consideration the lack of history data on increased frequency of thrombosis. Part of the examined group (the first ten on the table of the results) were smokers with mean usage of 15 cigarettes per day. The study was carried out on 25 women at the three stages of the hormonal cycle, but singly on the remaining 10 women in its beginning. Blood sample for examination was taken with anticoagulant (citrate) in the morning before breakfast and the activity of the inhibitor was determined by kinetic colorimetric method and chromatogenic Chromasin TN (a modification of Kamenov). The results were presented in percentages. The mean activity of antithrombin III was: means = 107.5%, which did not differ from the reference values. The activities at the three phases of the menstrual cycle did not differ significantly (p greater than 0.05). The results, obtained from the study, proved that hormonal contraceptive drugs did not reduce the activity of antithrombin III.

PIP: Antithrombin III is one of the most important inhibitors of serine proteases of coagulation and fibrinolysis. It inhibits the activity of thrombin and factor X. Its congenital or acquired reduction leads to an increased risk of thrombosis. The influence of the oral contraceptives Gravistat and Nonovlon was investigated on the activity of antithrombin III. 35 women 20-38 years old (average age 29.5 years) who had been taking the drugs for 2 to 10 years with an average duration of 2.5 years were examined. The instructions of the physician were complied with; and none of them had a family history of increased frequency of thrombosis. The first 10 patients had smoked an average of 10-15 cigarettes a day for at least a year. The 3 stages of the hormonal cycle were studied for 25 women (days 7, 14, and 21) as opposed to a single analysis for the remaining 10 women. A blood sample was taken with an anticoagulant (citrate) preprandially in the morning, and the activity of the inhibitor was carried out by the determination of citrate in the plasma by means of the kinetic calorimetric method and the hormonal substrate via the chromotogenic Chromasin TN method (as modified by Kamenov). The results showed that the average activity of antithrombin III was x = 107.5%, which did not differ from the reference value (x = 109.8 +or- 13.4%, p 0.05). The activities of the three phases of the menstrual cycle did not differ significantly, either (x = 101.3 for phase II and x = 104.5 for phase III, p 0.05). These results prove that these hormonal contraceptives did not reduce the activity of antithrombin III.

[Oral contraceptive agents and the fibrinolytic system]. / Oralni antikontseptivni sredstva i fibrinolitichna sistema.

The study included 35 women at the age of 20 to 38 years, using oral contraceptive drugs for a period of two to ten years. Changes in the activity of plasmin and alpha 2 antiplasmin were examined in the blood plasma. The study included three phases of the menstrual cycle (7-14-21 day) in 25 women. Kinetic methods with chromogenic substrates were used as Statchrom PLC was used for plasmin, but Chromosim AP (modification of Kamenov)--for alpha 2 antiplasmin. The applied contraceptive hormonal preparations were Gravistat 250 and Nonovlon. The mean activity of plasmin was x = 108.3%, but of alpha 2 antiplasmin x = 106.3%. Both values did not differ from that of the reference group (p greater than 0.05). The established slight tendency to a reduction in the activity of both examined parameters could be due to differences in the hormonal content of the preparations as well as to individual fluctuations of the hormonal cycle in the investigated patients. The two proteins participate in the acute reaction of the organism and change their concentrations quickly and this fact should be taken into consideration as well.

[Dynamic changes in the hemostatic indices of diabetics during biostator control]. / Dinamichni promeni na niakoi pokazateli na khemostazata pri diabetitsi po vreme na biostatoren kontrol.

In 25 patients with insulin-dependent diabetes and without microangiopathic complications the main hemostatic inhibitors antithrombin III, alpha-2-macroglobulin, and alpha-2-antiplasmin were examined before and after an optimal compensation of the carbohydrate metabolism was achieved. The patients were treated for 24 hours with the help of an artificial endocrine pancreas--biostator. The initial mean value of hyperglycemia of 15.61 mmol/l fell significantly to a mean value of 5.67 mmol/l at the end of the 24 hour treatment. During this 24 hour period the levels of the indices followed up did not change significantly. They were as follows: antithrombin III--98.48%, alpha-2-macroglobulin--112.25%, alpha-2-antiplasmin--110.68%. The lack of changes in the hemostatic inhibitors is explained by the short term biostator treatment.

Streptozotocin-induced diabetes in rat. I. Influence of hypertension and myocardial infarction on the development of vascular complications.

Streptozotocin diabetes in rats was complicated by spontaneous hypertension (SHR) and myocardial infarction (MIC), considered as "risk groups". Renal function was assessed on the basis of blood urea nitrogen (BUN) and albuminuria. BUN increased by 36% in Wistar diabetic group, by 100% in SHR + diabetes, and by 51% in MIR + diabetes. Morphologic changes were assessed by estimation of PAS-positive glycosaminoglycans and measurement of vascular wall thickness of glomerular arterioles. The risk groups showed exaggerated tendency for development of diabetic angiopathy. A significant imbalance between TXA2 and prostacyclin was found, which was reflected by TXB2/6-keto-PGF1 alpha (the stable metabolites of TXA2 and prostacyclin, respectively) ratio, which increased by 38% in Wistar diabetic rats, by 61% in SHR + diabetes, and by 133% in MIR + diabetes. These changes correlated very well with increased platelet aggregability (r = 0.70; p less than 0.05) and with increased lipid peroxide level (r = 0.60; p less than 0.05), but neither with total plasma cholesterol (r = 0.20), nor with plasma triglycerides (r = 0.34). Lipid peroxides increased 5-fold in Wistar diabetic rats, 6-fold in SHR + diabetes, and 5.5-fold in MIR + diabetes. A causative relationship between TXA2/PGI2 imbalance and lipid peroxide changes on one hand, and diabetic angiopathy, on the other, was suggested.

Pathogenesis of cardiovascular disorders in streptozotocin-induced diabetes in rat. II. Correlation between lipid peroxides, thromboxane A2/prostacyclin, and platelet aggregation in different stages of diabetes.

An attempt was undertaken to assess the relationship between the imbalance of lipid peroxides, thromboxane A2/prostacyclin and increased platelet aggregability during early (2 months) and late (6 months) stage of streptozotocin diabetes in rat. Thromboxane A2 and prostacyclin (PGI2) were estimated by their stable metabolic products TXB2 and 6-keto-PGF1 alpha respectively. The results showed: 1. There is a significant imbalance in TXA2 (a potent promoter of platelet aggregation) and PGI2 (a potent vasodilator and inhibitor of platelet aggregation). The ratio TXA2/PGI2 was increased by 38% in the early and by 69% in the late stage of diabetes. 2. Serum lipid peroxides increased significantly during early (four times) and late (five times) stage of diabetes. 3. There is a very good correlation between increased lipid peroxides and increased TXA2/PGI2 ratio (r = 0.71) in diabetic rats. 4. A pronounced increase in thrombin-induced platelet aggregation is consistent with the increased levels of lipid peroxides (r = 0.65) and TXA2/PGI2 ratio (r = 0.60). 5. All described changes correlate with the duration of the disease.

[Changes in the coagulation status of patients with chronic obstructive lung disease following the electrophoretic use of heparin]. / Promeni v koagulatsionniia status pri bolni s khronichna obstruktivna belodrobna bolest sled elektroforetichno prilagane na kheparin.

49 patients with chronic obstructive pulmonary disease and 40 healthy persons were examined. The hemocoagulation state indices were followed up before and after treatment. The patients with chronic obstructive pulmonary disease were classified into two groups: I gr.--treated without drugs acting on the hemocoagulation factors, II gr.--treated with heparin applied by electrophoresis. Significant changes of some of the basic indices of hemostasis were found. Following electrophoretic application of heparin they were considerably improved compared with the control group of patients treated without heparin. This kind of treatment is well tolerated by the patients and does not lead to untoward reactions.

[Fibrinopeptide A and protein C in heart patients with acute coronary syndromes]. / Fibrinopeptid A i protein C pri surdechno bolni s ostri koronarni sindromi.

In order to determine the role of thrombosis in the acute coronary syndromes the blood levels of fibrinopeptide A and protein C were examined with an enzyme-immune test in 48 patients treated in the cardiological clinic of the National Centre for Cardiovascular Diseases. 27 patients were with transmural myocardial infarction and 21 patients were with non-transmural myocardial infarction. The average time of the test from the onset of pain is 18.4 +/- 12.2 hours (from 3 up to 72 hours). The mean level for fibrinopeptide A for the whole group of patients is 4.95 +/- 3.1 ng/ml and that of protein C is 70.1 +/- 9.8%. For the group of patients with transmural myocardial infarction the level of fibrinopeptide A is 6.09 +/- 3.49 ng/ml and of protein C is 65.3 +/- 8.0%. For the patients with nontransmural myocardial infarction the levels are respectively 3.49 +/- 1.7 ng/ml for fibrinopeptide A and 76.3 +/- 8.3% for protein C. The difference between the two groups is statistically significant (p less than 0.005). In the patients with non-transmural myocardial infarction from whom the blood for the test was taken before the 24th hour the fibrinopeptide A level is 4.8 +/- 2.4 ng/ml and the protein C level is 69.0 +/- 7.8%. The deviations from the reference group are statistically significant (p less than 0.04). The practical importance of these results is discussed.

[Anticoagulants and changes in the coagulation status of patients with chronic obstructive lung disease and various degrees of respiratory failure]. / Antikoagulanti i promeni v koagulatsionniia status pri bolni s khronichna obstruktivna belodrobna bolest i razlichna stepen na dikhatelna nedostatuchnost.

The study includes 94 persons: 54 patients with chronic obstructive pulmonary disease and 40 healthy controls. The coagulation indices were followed up dynamically before and after heparin treatment. The patients with chronic obstructive pulmonary disease were classified into 3 groups in relation to the degree of respiratory failure. The results show significant changes in some of the basic hemostatic indices: decreased antithrombin III activity, increased alpha 2-macroglobulin and plasminogen activity, partial thromboplastin time shortening, increased erythrocyte, hemoglobin and hematocrit values. With deterioration of the respiratory failure these changes become more manifested which increases significantly the risk of pulmonary thromboembolism. The values of platelets, fibrinogen, prothrombin time, bleeding time, clotting time, alpha 2-antiplasmin and prekallikrein activity do not show any significant changes and are not reliable indices for hemostatic changes in patients with chronic obstructive pulmonary disease. The administration of heparin improves the changed basic indices. This is best expressed in patients with III degree respiratory failure. The parameters of external respiration and gas exchange improve parallelly with the improvement of the coagulation state.

[Glycosylated proteins and various hemostatic indices in diabetic retinopathy]. / Glikirani proteini i niakoi khemostazni polazateli pri diabetna retinopatiia.

The changes in the level of glycated proteins and some factors of coagulation were studied in 30 patients with diabetes mellitus--15 with and 15 without diabetic retinopathy. The mean level of glycoalbumin was elevated (2.9 +/- 0.8 mg) HMF (mg protein) without an authentic difference in the two subgroups. Glycohemoglobin was also increased (means--13.6 +/- 1%) in all studied subjects The activity of antithrombin III was high (means--222 +/- 53%) and the concentration--reduced--means--22.1 +/- 2.2 mg%, without authentic difference in the two subgroups. The concentration of alpha-2-macroglobulin, as well as its activity showed no significant deviations. Factor VIII (von Willebrand) was within reference limits (means--97.04 +/- 15.06%) with a tendency to lower values in the group without diabetic retinopathy. Fibrinogen level (means--4.3 +/- 1.2 g) was within the reference range, and FDP--increased in the majority of the examined. A syndrome of intensified latent coagulability, equivalent to chronic decompensated DIC, determined by the basic dismetabolism and non-enzymatic glycating of proteins has been outlined. The changes are more marked in the cases with diabetic retinopathy.

[Automatic and manual methods for counting the thrombocytes in the blood]. / Avtomatichen i manualen metod za izbroiavane na trombotsitite v kruvta.

The results are compared from the platelet count in blood via chamber method with phase contrast and via electronic method with "Thrombocounter C". The reproducibility was studied in a series in the low, referent and high region. The electronic-automatic method gives a better reproducibility than the chamber method in all three regions. The poorest is the reproducibility in the low region where VC of both methods were the closest. The results from the two methods are in a high positive correlation (r = 0.9145, n = 61), the arithmetical mean from the electronic method being insignificantly higher than the mean of the chamber method, p greater than 0.05. In the low region, with platelets under 80 X 10(9)/l, the reliability of the electronic-automatic method is decreased. The results from the chamber and electronic-automatic method have a normal distribution. The electronic-automatic method is several times faster and less tiresome than the chamber one.

Enzymes and cytomorphological sperm alterations in some diseases of the male reproductive system.

In this work the alterations of some acrosomal enzymes and gamma-GT were studied in diseases of the male genital tract. Thirty-two patients with vascular diseases, seven with inflammatory diseases and twenty-four controls were investigated. In all patients the sperm morphology was studied and the following enzymes were assayed: beta-glucuronidase, beta-galactosidase, beta-glucosidase and gamma-GT. In all patients with vascular and inflammatory diseases we found severe hypokinesis and decreased number of spermatozoa. The activity of all four enzymes in both pathological groups was decreased in comparison with the controls, and this decrease was significant for all enzymes in males with vascular diseases and for beta-galactosidase and beta-glucosidase in cases with inflammatory diseases. Our data show that the decrease of spermatozoal count was accompanied by a decreased enzyme activity. The role of decreased sperm plasma enzyme activity, the decreased production of spermatozoa and quantitative changes in structure and acrosome enzyme content are discussed.