Silica-metal core-shell nanostructures.

Silica-metal nanostructures consisting of silica cores and metal nanoshells attract a lot of attention because of their unique properties and potential applications ranging from catalysis and biosensing to optical devices and medicine. The important feature of these nanostructures is the possibility of controlling their properties by the variation of their geometry, shell morphology and shell material. This review is devoted to silica-noble metal core-shell nanostructures; specifically, it outlines the main methods used for the preparation and surface modification of silica particles and presents the major strategies for the formation of metal nanoshells on the modified silica particles. A special emphasis is given to the Stöber method, which is relatively simple, effective and well verified for the synthesis of large and highly uniform silica particles (with diameters from 100 nm to a few microns). Next, the surface chemistry of these particles is discussed with a special focus on the attachment of specific organic groups such as aminopropyl or mercaptopropyl groups, which interact strongly with metal species. Finally, the synthesis, characterization and application of various silica-metal core-shell nanostructures are reviewed, especially in relation to the siliceous cores with gold or silver nanoshells. Nowadays, gold is most often used metal for the formation of nanoshells due to its beneficial properties for many applications. However, other metals such as silver, platinum, palladium, nickel and copper were also used for fabrication of core-shell nanostructures. Silica-metal nanostructures can be prepared using various methods, for instance, (i) growth of metal nanoshells on the siliceous cores with deposited metal nanoparticles, (ii) reduction of metal species accompanied by precipitation of metal nanoparticles on the modified silica cores, and (iii) formation of metal nanoshells under ultrasonic conditions. A special emphasis is given to the seed-mediated growth, where metal nanoshells are formed on the modified silica cores with deposited metal nanoparticles. This strategy assures a good control of the nanoshell thickness as well as its surface properties.

Synthesis of OMS Materials and Investigation of Their Acceptor-Donor Characteristics.

Three ordered mesoporous siliceous (OMS) materials known as MCM41s-unmodified MCM-41C16 ("C16"), and two MCM41s with different surface functionalities: MCM-41C16-SH ("C16-SH") and MCM-41C16-NH2 ("C16-NH2")-were synthesized and studied by inverse gas chromatography in order to determine their acceptor-donor properties. The specific retention volumes of nonpolar and polar probes that were chromatographed on these ordered mesoporous silica adsorbents were evaluated under infinite dilution conditions. Two methods were employed to calculate the standard free energy of adsorption, ΔGads, of each chromatographed probe on the basis its specific retention volume. These ΔGads values were then employed to estimate the van der Waals contribution and the specific contribution of the free surface energy for each MCM41. DN values (donor numbers, based on the Gutmann scale) and AN* values (acceptor numbers, based on the Riddle-Fowkes scale) were employed to determine the values of parameters that characterize the ability of the MCM41s to act as electron acceptors (parameter: KA) and donors (parameter: KD). Considering the different compositions of the probes, each of which has different acceptor-donor properties, a new chromatographic test to supplement the Grob test is suggested.

Modeling neuron-glia interactions: from parametric model to neuromorphic hardware.

Recent experimental evidence suggests that glial cells are more than just supporting cells to neurons - they play an active role in signal transmission in the brain. We herein propose to investigate the importance of these mechanisms and model neuron-glia interactions at synapses using three approaches: A parametric model that takes into account the underlying mechanisms of the physiological system, a non-parametric model that extracts its input-output properties, and an ultra-low power, fast processing, neuromorphic hardware model. We use the EONS (Elementary Objects of the Nervous System) platform, a highly elaborate synaptic modeling platform to investigate the influence of astrocytic glutamate transporters on postsynaptic responses in the detailed micro-environment of a tri-partite synapse. The simulation results obtained using EONS are then used to build a non-parametric model that captures the essential features of glutamate dynamics. The structure of the non-parametric model we use is specifically designed for efficient hardware implementation using ultra-low power subthreshold CMOS building blocks. The utilization of the approach described allows us to build large-scale models of neuron/glial interaction and consequently provide useful insights on glial modulation during normal and pathological neural function.

Efeitos da metadona ou do neostigmine, associados à lidocaína administrados pela via epidural em cães / Effects of methadone or neostigmine in combination with lidocaine for epidural anesthesia in dogs

Seis cães adultos, de raças e sexos variados, com peso de 13,3±3,4kg (média±DP), foram utilizados no estudo. Os animais foram tranqüilizados com acepromazina (0,1mg/kg, IV) e, após 30 minutos, foram aleatoriamente submetidos à anestesia epidural com um dos seguintes tratamentos: lidocaína 2 por cento 0,25ml/kg (controle); neostigmine 0,01mg/kg+lidocaína (NEO); metadona 0,3mg/kg+lidocaína (MET). Todos os animais foram submetidos aos três tratamentos com intervalo mínimo de uma semana. Foram mensuradas as freqüências cardíaca (FC) e respiratória (FR), a pressão arterial sistólica (PAS), o tempo para a perda do reflexo interdigital, a duração e a altura do bloqueio sensitivo, durante um período de 90 minutos. Não houve diferença significativa entre os tratamentos nos valores de FC, PAS e FR, bem como na duração do bloqueio sensitivo e no tempo para a perda do reflexo interdigital. No grupo MET, houve diminuição de FC dos 30 aos 90 minutos em relação ao valor basal. Bloqueio sensitivo mais cranial também foi observado em MET. A associação de neostigmine ou metadona não prolongou o período hábil de anestesia epidural produzido pela lidocaína em cães. A metadona, mas não o neostigmine, parece estender mais cranialmente o bloqueio epidural pela lidocaína.

Six mature mongrel dogs of both genders, weighing 13.3±3.4kg (mean±SD) were used in the present research. Thirty minutes after premedication with intravenous acepromazine (0.1mg/kg, IV), dogs were randomly assigned to receive epidural administration of one of following three treatments: 2 percent lidocaine 0.25ml/kg (control), or neostigmine 0.01mg/kg plus lidocaine (NEO), or methadone 0.3mg/kg plus lidocaine (MET). All dogs received all treatments in a cross-over design with at least one-week interval. Heart rate (HR), respiratory rate (RR), systolic arterial pressure (SAP), time to loss of pedal withdrawal reflex, duration of epidural anesthesia, and cranial spread of epidural anesthesia were evaluated for 90 minutes. No differences among treatments in HR, RR, SAP, duration of anesthesia, and time to loss of pedal withdrawal reflex were found. In MET, HR decreased from 30 to 90 minutes compared to baseline and there was a higher cranial spread of epidural anesthesia than in controls and NEO animals. Neostigmine or methadone did not prolong epidural anesthesia with lidocaine in dogs. Methadone, but not neostigmine, appeared to result in more cranial spread of epidural anesthesia with lidocaine.

An improved methodology for adsorption characterization of unmodified and modified silica gels.

An improvement in the adsorption characterization of the surface and structural properties of unmodified and modified mesoporous silica gels is presented. This improvement was achieved by selection of proper macroporous silica as the reference solid for adsorption characterization of porous silica gels. Experimental illustration is provided for unmodified and n-octyl-modified silica gels of different bonding density. The surface and structural properties of these silica gels were characterized by utilizing the standard adsorption data for both unmodified and octyl-modified LiChrospher Si-1000 macroporous silica gels. It was shown that the standard nitrogen adsorption data have an appreciable influence on the analysis of the pore size and surface properties of silica gels. This analysis can be improved by selecting the reference solid of the surface properties close to those of the silica gel studied.

Monitoring Changes in Surface and Structural Properties of Porous Carbons Modified by Different Oxidizing Agents.

A series of active carbons and carbon blacks was oxidized with various oxidizing agents such as hydrogen peroxide, perchloric acid, and nitric acid. Their surface and structural properties were evaluated by use of nitrogen and water vapor adsorption isotherms, as well as high-resolution thermogravimetry. A comparative analysis of differential thermogravimetric curves and adsorption isotherms of nitrogen and water vapor for the samples studied showed that the surface properties of oxidized carbons depend on the type of oxidizing agent as well as oxidation conditions. This comparison shows that the modification of carbons with concentrated nitric acid caused the most pronounced surface and structural changes. These changes were much smaller for the samples modified with perchloric acid and hydrogen peroxide. Copyright 1999 Academic Press.

[The effect of vitamin E on cortisol and lactate levels and on the acid-base equilibrium in calves exposed to transportation stress]. / Vplyv vitamínu E na hladinu kortizolu, laktátu a acidobázickú rovnováhu u teliat vystavených transportnej zátazi.

The objective of this study was to examine the effect of vitamin E administration on plasma levels of cortisol and lactate, and on acid base balance in transported calves. In the study, eight calves, aged approx. ten days, divided into two groups, were used. 20 mg of tocopherol-acetate per kg body weight were administered orally to each of the four experimental calves 24 hours before loading. The calves were transported by road for 3 hours. Blood samples collected before and after the transportation were examined for acid base balance, lactate, and plasma vitamin E and cortisol levels. The administration of vitamin E led to a decrease of cortisol levels in 24 hours (from 7.6 +/- 9.5 to 4.2 +/- 0.2 nmol/l) as well as to a significant increase (p < 0.05) of plasma vitamin E levels 26 h after administration (from 2.52 +/- 1.36 to 12.28 +/- 6.14 mumol/l). There was no difference between the groups in cortisol response due to transportation stress (Tab. III). The transportation caused typical stress changes in lactate levels and acid base balance (lactacidaemia and the tendency to acidosis, Tab. III, IV). There was approx. threefold increase in plasma lactate concentrations due to transportation (from 2.49 +/- 0.69 to 6.35 +/- 3.75 mmol/l). The results of the present study demonstrated metabolic changes which has been reported to be typical of mild physiological stress reaction. In the present study, vitamin E had no significant effect on plasma levels of cortisol, and lactate, and acid-base balance.

Effect of vitamin E on some leucocytic parameters and functions in transported calves.

The objective of this investigation was to determine the effect of vitamin E administration on leucocyte parameters and some of their functions in transported calves. In the study 8 calves, aged approx. 10 days, divided into two groups, were used. 20 mg of tocopheryl-acetate per kg body weight were administered orally to each of the 4 experimental calves 24 hours before loading. The calves were transported by road for 3 hours. Blood samples collected before and after the transportation were examined for total and differential leucocyte counts, T-lymphocyte subpopulation, phagocytic activity, leucocyte migration, serum immunoglobulin levels, and for plasma vitamin E and cortisol levels. The animals showed a leucocytosis with neutrophilia and lymphopenia after transportation. The administration of vitamin E led to a decrease of cortisol level in 24 hours. There was no difference between groups in cortisol reaction due to transportation stress. Leucocyte migration has been less inhibited in the control group after unloading. A mild decline in phagocytic activity was observed 3 hours after transportation. Serum immunoglobulins were unaffected by both vitamin E administration and transportation. Vitamin E had no significant effect on leucocyte function and cortisol levels in present study.

[Changes in blood levels of progesterone, triiodothyronine and thyroxine and the results of quantitative histological analysis of the placentoma and corpus luteum in cows after prolonged labor]. / Zmeny koncentrácie progesterónu, trijódtyronínu a tyroxínu v krvi a výsledky kvantitatívnej histologickej analýzy placentómu i zltého telieska kráv po protrahovanom pôrode.

Changes in the cell structure of the placentoma and the corpus luteum were subjected to quantitative histological investigation, parallel with the examination of the concentrations of progesterone (P4), triiodotyronine (T3) and tyroxin (T4) during parturition (Oth hour) and two and six hours after parturition. The hormone concentrations were determined by the RIA method. The results of the quantitative histological analysis of the placentomae and the corpus luteum suggest that when the placenta is retained there is a significantly higher number of maintained epithelial cells in the placentoma crypts and a higher number of unchanged small, dark and large, light lutein serraetion cells in the biopsy of the corpus luteum during the period under investigation. The morphological finding significantly correlates with higher concentrations of P4 in the blood of the cows with retained placenta, as compared with those whose placenta was not retained. It can be derived from the pattern of changes in T3 and T4 concentrations, compared with P4 and with the histological finding, that there is a functional relationship between the placentoma, corpus luteum, and the thyroid gland.

[Radioimmunologic determination of progesterone and rectal ovarian palpation in embryonic death in cows]. / Rádioimunologické stanovenie progesterónu a rektálna palpácia ovárií pri embryonálnej mortalite kráv.

Repeated radio-immunological assays of progesterone in milk and ovary rectal palpation were used for indirect determination of embryonal mortality in cows. Milk sampling and rectal examination were made in the insemination period and then in two- to three-day intervals, mostly from the 21st day after insemination till the early pregnancy determination made after the 42nd day on the basis of the double wall phenomenon. Observation was made in 185 animals from two herds. Embryonal mortality was found in 9.06% out of 289 evaluated inseminations, which prolongs the oestral cycle over 25 days. The monitoring corpus luteum function in connection with rectal ovary palpation supplemented by oestrus, ovulation and insemination control enable a more objective indirect diagnosis of embryonal losses prolonging the oestral cycle.

[Pregnancy in dairy cows in various times of the year in relation to thyroxine and triiodothyronine levels]. / Zabrezávanie dojníc v róznych rocných obdobiach vo vztahu ku koncentráciám tyroxínu (T4) a trijódtyronínu (T3).

Conception of dairy cows was investigated in relation to changes in thyroxine (T4) and triiodothyronine (T3) concentrations in March (n = 15), June (n = 10) November (n = 7) after oestrus synchronization by cloprostenol (Oestrophan Spofa) at a dose of 0.05 mg per head. The cows were inseminated from 8.00 to 9.00 o'clock a.m. Blood was taken from 9.00 to 10.00 a.m. from v. jugularis on the day of Oestrophan treatment (-3rd day), on the day of insemination (day 0), and on the 6th and 21st day after insemination. The lowest percentage of pregnant cows (26.67%) was recorded after the March insemination, the highest (50.0%) after the June insemination. 42.86% of cows became pregnant in November. Concentrations T4 in pregnant animals on the day 0 of March insemination were 67.55 +/- 16.95 nmol.1-alpha of serum. Nonsignificant decrease to value 65.60 +/- 10.06 and 49.33 +/- 17.47 nmol.l-1 of serum were observed on the day of June and November insemination. In T3 concentrations an average decrease from the values of 2.53 +/- 0.67 nmol.l-alpha on day 0 of the March insemination to 1.48 +/- 0.67 nmol.l-alpha on day 0 of the June insemination was observed, as well as a significant decrease to 0.80 +/- 0.45 nmol.l-1 of serum (P less than 0.05) on the day of the November insemination. Considering the results we suppose that the conception of dairy cows has an indirect relationship to thyroid hormones.

[Changes in surface follicles and ovarian weight in testing for responsiveness in dairy cows after induction of superovulation using PMSG and cloprostenol]. / Zmeny povrchových folikulov a hmotnosti vajecníkov pri testovaní responzibility dojníc po indukcii superovulácie PMSG a cloprostenolom.

We evaluated the ovaries of 34 cows cross-bred of the Slovak Pied and Lowland Black-pied breeds which were culled and intended for slaughter during the winter type of feed rations. For superovulation treatment we used PMSG in the preparation Serum Gonadotropin (Bioveta, Nat. Ent., Ivanovice na Hané) and cloprostenol in the preparation Oestrophan inj. Spofa. We weighed the excised ovaries, fixed them in formalin 10% and made a quantitative evaluation of the surface follicles and differentiated them into recruited and selected or dominant follicles. We determined the concentration of 17 beta-estradiol and testosterone with the aid of the 3H RIA set from the firm Sorin after extraction by diethylether with separation of free and bound hormone with active charcoal. 72 hours after the giving of cloprostenol 43% reacted positively to superovulation treatment and after seven days a 50% positive response was recorded. After a dose of 2000 i. u. of PMSG (n = 6) embryo was obtained, whereas after 3000 i. u. of PMSG (n = 8) we flushed out eight embryos, of which four zygotes were suitable for transfer. After a higher dosage of PMSG there was an increase in the average weight of the ovaries, in right-hand ovaries significantly with P less than 0.05. After super-ovulation treatment the concentration of 17 beta-estradiol (E2) in the follicular fluid from follicles seven days after insemination was found to be so low as to be below the limit of detection, with the exception of four samples (mean = 8.60 nmol.l-1). The greatest concentration of E2 was from animals (n = 5) 72 hours after the giving of cloprostenol--1099.61 nmol.l-1) of follicular fluid. The concentration of testosterone was lower in the follicles of untreated cows in the follicular phase (mean = 5.92 nmol.l-1) compared with the follicles of super-ovulated animals the seventh day after insemination (mean = 14.12 nmol.l-1). The number of recruited and especially selected surface antral follicles 72 hours (n = 7) after the giving of cloprostenol and seven days (n = 8) after insemination was significantly higher in the group of brood cows reacting positively to superovulation in comparison with the animals which did not respond. It appears that the simultaneous monitoring of hormonal and morphological changes in the follicular system will help in objectivising the evaluation of the functional activity of stimulated follicles.

[The effect of beta-carotene on thyroxine and cholesterol levels in pregnant heifers before and after parturition]. / Vplyv beta-karoténu na koncentrácie tyroxínu a cholesterolu u telných jalovíc pred pôrodom a po pôrode.

Thyroxine (T4) and cholesterol concentrations and their dynamic changes and differences were studied in 20 pregnant heifers 10 days before calving until 56 days after calving. Ten control heifers were fed the feed ration for pregnant heifers according to Czechoslovak Standard CSN 46 7070. The feed ration given to another ten (experimental) heifers was fortified with 300 mg of synthetic beta-carotene per head/day within the period of five months before insemination, during pregnancy and till the 56th day after parturition. As suggested by the regression function of straight line, no obvious differences were recorded in the dynamic changes of T4 before parturition and during the first days after parturition. T4 concentrations had a generally descending tendency in both groups, the lowest values being recorded in the 48th hour in the experimental group and the 24th hour in the control. A marked increase of T4 concentrations with the values significantly higher in the control group than in the experimental group was observed between the 21st and 35th day after calving. A medium increase of cholesterol concentrations was found in the heifers given rations fortified with beta-carotene. No significant differences in cholesterol concentrations were observed between the two groups, except in the 72nd hour and the seventh day. Significant T4: cholesterol correlations were recorded in the experimental animals in the first and second hours, on the 42nd day (P less than 0.05), and in the 72nd hour (P less than 0.001); in the control group these observations were made the seventh day before calving and in the sixth hour and on the 14th, 21st and 56th days (P less than 0.05) after calving. It is inferred from the results that beta-carotene interferes with the activity of the thyroid gland and the production of its hormones, and that the increases or decreases of the activity of this gland, caused by beta-carotene, influence the metabolism of cholesterol in the body.

[Correlation between the thyroxine, 17-beta-estradiol and luteinizing hormones in the systemic circulation and the rectal and vaginal temperature in heifers and cows after administration of cloprostenol]. / Korelácia medzi tyroxínom, 17-beta-estradiolom, luteinizacným hormónom v systémovom obehu a rektálnou i vaginálnou teplotou jalovíc a kráv po podaní cloprostenolu.

Changes in the concentration of 17beta-oestradiol (E2) and luteinizing hormone (LH) and in the rectal and vaginal temperatures (RT and VT) were studied along with the changes in thyroxine concentration (T4) in three cows and three heifers in the luteal stage of the cycle; the animals had been intramuscularly treated with 2 ml Oestrophan (cloprostenol). The closeness of the correlation between T4 and the remaining parameters under study was determined by the calculation of the correlation coefficient and statistical significance. The concentrations of T4 before and during cloprostenol administration were high in comparison with the post-treatment levels. E2 concentrations at cloprostenol administration time were much higher than those recorded before administration. After treatment the concentrations of T4 and E2 sank. The first E2 peak, recorded in the 44th hour, was immediately followed by a marked drop of E2 as well as T4, the lowest values of both being recorded in the 52nd and 56th hour. The second peak of E2 in the 60th hour was followed by a slow but steady decrease. The rise of the concentration of T4 after the 56th hour was slow and reached the peak in the 74th hour; after a partial decrease no further marked changes in concentrations were recorded. LH concentrations rose at a slow rate to reach the peak in the 64th hour. After a rapid decline they reached the pre-peak value in the 70th hour. The lowest RT and VT levels were recorded in the 54th and 94th hour. It can be assumed on the basis of the behaviour of the hormones and the evaluation of their correlations that thyroidal hormones are involved in the stimulation of the synthesis of ovarial oestrogens which tend, after their synthesis, to eliminate from circulation the T4 as well as their own levels and thereby to influence (as feedback) the stimulation of T4 synthesis, their own synthesis, and LH.

[Cervical mucus in the heifer uterus during heat and insemination after feeding with synthetic beta-carotene]. / Cervikálny hlien maternice jalovíc v case ruje a inseminácie po skrmovaní syntetického beta-karoténu.

The effect of beta-carotene was studied, as exerted on the amount, ductility, pH value, arborization and sperm survival time in the medium of the cervical mucus of heifers included in the breeding stock. The measurements were taken during oestrus and mating. The animals were divided into four groups. The first group was given diet containing no carotene. In the other groups (II, III, IV) the animals were fed a supplement of synthetic beta-carotene, the doses being 100, 200 and 400 mg per head/day. The survival of spermatozoa in the medium of cervical mucus was found to be significantly longer in the fourth group (115.2%) as compared with the first group (61.8%). In the statistical comparison of these results the P level was less than 0.05. Statistically significant differences were observed in the amount, ductility and arborization between the pregnant heifers and oestrus return ones in the first group. These differences were reduced after the addition of beta-carotene to feed. Beta-carotene saturation in the feed ration was not found to exert any significant influence on the pH value of cervical mucus. As suggested by the evaluation of the results and their comparison with literary data, sperm survival time in cervical mucus was the only trait influenced significantly by beta-carotene: no significant effect was exerted on the other parameters under study. Beta-carotene seems to influence the role of polyfactorial factors in the control of steroidogenesis.

[Micromorphology of the endometrium of dairy cows after estrus synchronization with cloprostenol]. / Mikromorfológia endometria dojníc po synchronizácii ruje cloprostenolom.

Trials were conducted to study and describe the micromorphological parameters of endometrium in five cows of the Black-Pied breed after the expiration of the synchronizing effect of cloprostenol in the Oestrophan inj. Spofa preparation. Two animals four to five days after oestrus were used as control and three cows on the sixth day of sexual cycle with rectally palpated corpora lutea were treated intramuscularly with 0.5 mg cloprostenol in 2 ml of Oestrophan. On the eighth day from the administration of the product, samples of uterine horns were obtained by necropsy and were subjected to histological preparation. Paraffin slices, 7 micron thick, were stained with haematoxylin-eosine by the PAS reaction. Changes were observed in the ipsilateral and contralateral uterine horns in relation to active corpus luteum. A state resulting from previous oedematization, with ample thin connective tissue and fading cell infiltration after the administered preparation, was described in the subepithelial layer of endometrium. The occurrence of intraepithelial lymphoid cells was observed in the surface epithelium of endometrium. A significant increase in the thickness of endometrium (P less than 0.001) was observed to persist on the eighth day after the administration of cloprostenol. An increase in the thickness of surface epithelium, ipsilateral with the corresponding corpus luteum, was on the level of significance (P less than 0.05). The subsurface cells of endometrial glands shrunk significantly after the administration of the preparation, both ipsilaterally (P less than 0.001) and contralaterally (P less than 0.001) to the corpus luteum, like in the glands in the depth of the mucous membrane just above myometrium (P less than 0.01). The occurrence of intraepithelial lymphoid cells decreased significantly after the administration of cloprostenol.

[Histology of the oviduct epithelium of dairy cows after estrus synchronization with cloprostenol]. / Histológia epitelu vajcovodu dojníc po synchronizácii ruje cloprostenolom.

After fading away of the effect of cloprostenol contained in the Oestrophan inj. Spofa preparation, the qualitative and quantitative changes in the epithelium of oviduct ampulla and isthmus of dairy cows were studied. Three dairy cows in the fourth to fifth day after heat were used as control, three cows with the rectally palpated active corpus luteum were given 0.5 mg cloprostenol i. m. On the eighth day after treatment, samples were taken from ampulla and isthmus by means of necropsy. After histological treatment, the samples were evaluated microscopically. Histological staining with hematoxylin-eosine, PAS reaction and PAS reaction with nucleus staining with Harris hematoxylin were used to describe the occurrence of the so-called pale cells. In accordance with the literary data, these cells are believed to be intraepithelial lymphocytes, the function of which will have to be further researched and determined objectively. On the eighth day after cloprostenol administration or on the fourth to fifth day after ovulation in the ipsilateral ovary, a significant decrease in epithelium thickness close to infundibulum and in the depth of ampulla (P less than 0.001) was observed. The changes in the contralateral left side were not significant. After cloprostenol application, the multiplication of nail-like cells in the right-side oviduct ampulla was statistically significant (P less than 0.05).

[The follicular system of bovine ovaries after estrus synchronization using the luteolytic action of cloprostenol]. / Folikulárny systém vajecníkov kráv po synchronizácii ruje luteolytickým pôsobením cloprostenolu.

Oestrus synchronization was studied in samples from six cows of the Black-Pied Lowland breed. Three cows four to five days from oestrus were used as the control; three animals with marked periodic corpora lutea were given an i. m. injection of 0.5 mg cloprostenol. The eighth day from the administration of the preparation, the ovaries of the cows were excised and, after histological processing in a simultaneous series in a 4mm interval, the preparations were subjected to qualitative and quantitative microscopic evaluation. The structure of non-atretic and atretic follicles was described in different stages of the atretic process. The lymphoid cells of atretic follicles were observed to penetrate into the granulosa membrane. A multiplication of non-atretic tertiary follicles was observed after the administration of cloprostenol. This multiplication was more pronounced on the right ovary where the preceding ovulation had taken place (P less than 0.01). The treated animals, compared with the controls, showed a significant multiplication of tertiary follicles at early atresia and at total collapse atresia (P less than 0.001), whereas the number of follicles with contractive atresia showed a significant decrease (P less than 0.001). The results suggest that cloprostenol can influence follicle population mostly through the stimulation of the growth and ripening of tertiary follicles; its modulation effect seems manifest itself in cooperating relation with gonadotrophic hormones, mainly with the follicular secondary hormone (FSH), in the theory of the complex effect of proteohormones .

[Concentration of progesterone and thyroxine in the luteal phase of the cycle in heifers after administration of estradiol benzoate]. / Koncentrácia progesterónu a tyroxínu v luteálnej fáze cyklu jalovíc po ovplyvnení estradiol benzoátom.

The effect of current 48-hour infusion of estradiol benzoate (EB) on the dynamics of the concentration of progesterone (P) and thyroxine (T4) was studied in four heifers in the luteal stage of their cycle. The parameters were evaluated in three intervals: infusion (A), post-infusion (B) and "uninfluenced" interval (C). In the course of infusion the concentrations of P in three animals had a markedly descending tendency. The P concentration increase in the 36th hour of infusion was maintained also during the post-infusion interval. The decrease in P in the third, "uninfluenced", interval was replaced by a new rise towards the end. One heifer showed an increase in P concentrations at the beginning of EB infusion. A decrease was recorded towards the end of the interval. The concentration decreased in the post-infusion period. A comparatively high concentration of P in the "uninfluenced" interval was again replaced by a drop towards the end in the 286th hour. The concentration of T4 in three heifers had a descending tendency in the infusion and post-infusion intervals. The decrease in the infusion interval was more pronounced. In the "uninfluenced" interval the T4 concentrations increased step by step. In one heifer the concentration of T4 slightly increased during infusion. A decrease was recorded in the post-infusion and "uninfluenced" interval. Rectal examination in the 172nd hour revealed the original corpus luteum in three animals and the production of the corpus luteum in the same ovary was found in this period in one heifer. In the 88th hour this animal showed clinical manifestations of oestrus. On the basis of the dynamics of the studied hormones and clinical studies, the thyroid hormones can be regarded as an important secondary factor involved in the permanent cyclic changes in reproduction process.

[Thyroxine and progesterone levels in cows and heifers after administration of Oestrophan (Spofa) in the luteal phase of the cycle]. / Hladiny tyroxínu a progesterónu u kráv a jalovíc po podaní oestrophanu (Spofa) v luteálnej fáze cyklu.

Thyroxine and progesterone levels were studied in cows and heifers in the luteal stage of the cycle after the application of the synthetic analogue of prostaglandine of group F2 alpha: Oestrophan Spofa. The preparation was administered at a rate of 0.5 mg in 2 ml per animal. The thyroxine and progesterone levels were determined radioimmunologically. The administration of Oestrophan led to a reduction in the progesterone level from the initial value of 17.33 +/- 2.73 nmol/l of serum to 7.69 +/- 1.17 nmol/l of serum an hour after the application, followed by slow decrease below the value 1.59 +/- 0.22 nmol/l of serum at the 24th hour. The initial levels of thyroxine with the average values of 122.11 +/- 23.41 nmol/l of serum were comparatively high. An hour from application of the preparation, a significant decrease to the average levels of 88.14 +/- 16.26 nmol/l of serum (P less than 0.05) was recorded with a significant negative correlation. The correlation coefficient r = -83316, P less than 0.01. The thyroxine level decreases to the values of 24.20 +/- 9.26 nmol/l of serum and 24.12 +/- 6.68 nmol/l of serum, P less than 0.01, at the 52nd to 56th hour, i. e. at the time when the pre-ovulation peak of oestrogens can be expected. A statistically significant correlation--even despite the fact that a highly significant decline in thyroxine and progesterone had been observed--was recorded in none of the cases in the subsequent period of study, except the first hour. It can be assumed from the results that the thyroid hormones are among the links acting at more levels of the regulatory biological circuit responsible for the physiological course of ovulation and reproduction process.