Nanohydroxyapatite as a Biomaterial for Peripheral Nerve Regeneration after Mechanical Damage-In Vitro Study

Hydroxyapatite has been used in medicine for many years as a biomaterial or a cover for other biomaterials in orthopedics and dentistry. This study characterized the physicochemical properties (structure, particle size and morphology, surface properties) of Li⁺- and Li⁺/Eu³⁺-doped nanohydroxyapatite obtained using the wet chemistry method. The potential regenerative properties against neurite damage in cultures of neuron-like cells (SH-SY5Y and PC12 after differentiation) were also studied. The effect of nanohydroxyapatite (nHAp) on the induction of repair processes in cell cultures was assessed in tests of metabolic activity, the level of free oxygen radicals and nitric oxide, and the average length of neurites. The study showed that nanohydroxyapatite influences the increase in mitochondrial activity, which is correlated with the increase in the length of neurites. It has been shown that the doping of nanohydroxyapatite with Eu³⁺ ions enhances the antioxidant properties of the tested nanohydroxyapatite. These basic studies indicate its potential application in the treatment of neurite damage. These studies should be continued in primary neuronal cultures and then with in vivo models.

Carvedilol Inhibits Matrix Metalloproteinase-2 Activation in Experimental Autoimmune Myocarditis: Possibilities of Cardioprotective Application

AIMS

Acute myocarditis is a potentially lethal inflammatory heart disease that frequently precedes the development of dilated cardiomyopathy and subsequent heart failure. At present, there is no effective standardized therapy for acute myocarditis, besides the optimal care of heart failure and arrhythmias in accordance with evidence-based guidelines and specific etiology-driven therapy for infectious myocarditis. Carvedilol has been shown to be cardioprotective by reducing cardiac pro-inflammatory cytokines present in oxidative stress in certain heart diseases. However, effects of carvedilol administration in acute myocarditis with its impact on matrix metalloproteinases' (MMPs) activation have not been elucidated.

METHODS AND RESULTS

Carvedilol in 3 doses (2, 10, and 30 mg/kg) was given daily to 3 study groups of rats (n = 8) with experimental autoimmune myocarditis by gastric gavage for 3 weeks. In comparison to untreated rats (n = 8) with induced myocarditis, carvedilol significantly prevented the left ventricle enlargement and/or systolic dysfunction depending on the dose in study groups. Performed zymography showed enhanced MMP-2 activity in untreated rats, while carvedilol administration reduced alterations. This was accompanied by prevention of troponin I release and myofilaments degradation in cardiac muscle tissue. Additionally, severe inflammatory cell infiltration was detected in the nontreated group. Carvedilol in all doses tested, had no impact on severity of inflammation. The severity of inflammation did not differ between study groups and in relation to the untreated group.

CONCLUSIONS

The protective effects of carvedilol on heart function observed in the acute phase of experimental autoimmune myocarditis seem to be associated with its ability to decrease MMP-2 activity and subsequently prevent degradation of myofilaments and release of troponin I while not related to suppression of inflammation.

Effect of quercetin-5'-sulfonic acid sodium salt on SOD activity and ADMA/DDAH pathway in extracorporeal liver perfusion in rats

BACKGROUND

Quercetin-5'-sulfonic acid sodium salt (NaQSA) exerts good aqueous solubility, strong antioxidant activity and low toxicity.

OBJECTIVES

The aims of this study were to investigate the effect of NaQSA on superoxide dismutase (SOD) activity and ADMA/DDAH pathway during extracorporeal liver perfusion (ELP).

MATERIAL AND METHODS

The study was carried out on male Wistar rats. Isolated livers were perfused with Krebs-Henseleit bicarbonate buffer (KHB) + 1 microM ADMA (group C), or with KHB + 1 microM ADMA and either 10 microM NaQSA (Q10) or 50 microM NaQSA (Q50). In group 0 (sham) livers were perfused with KHB alone. Levels of ADMA, alanine (ALT) and aspartate (AST) aminotransferases activities were measured during perfusion. After 90 min. of perfusion superoxide dismutase (SOD) and dimethylarginine dimethylaminohydrolase (DDAH) activities were estimated in liver homogenates.

RESULTS

DDAH activity in Q10 group was significantly higher as compared to control and Q50 groups. No significant differences were observed between Q50 and control group. The decrease in ADMA concentration during perfusion was observed in all groups, but the most pronounced in the group Q10 and the least in group Q50. During perfusion AST activities were the lowest in Q50 group. No significant difference in SOD activity in groups perfused with NaQSA as compared to control group was noted.

CONCLUSIONS

The impact of NaQSA on ADMA/DDAH system depends on its concentration. In lower concentration NaQSA exerted some beneficial properties which vanished in higher concentration. No increase in SOD activity during perfusion with NaQSA was observed.

Benzylpenicillin, acetylcysteine and silibinin as antidotes in human hepatocytes intoxicated with alpha-amanitin

Fatalities due to mushroom poisonings are increasing worldwide, with high mortality rate resulting from ingestion of amanitin-producing species. Intoxications caused by amanitin-containing mushrooms represent an unresolved problem in clinical toxicology since no specific and fully efficient antidote is available. The objective of this study was a comparative evaluation of benzylpenicillin (BPCN), acetylcysteine (ACC) and silibinin (SIL) as an antidotes in human hepatocytes intoxicated with alpha-amanitin (alpha-AMA). All experiments were performed on cultured human hepatocytes. Cytotoxicity evaluation of cultured cells using MTT assay and measurement of lactate dehydrogenase (LDH) activity was performed at 12, 24 and 48h of exposure to alpha-AMA and/or antidotes. The significant decline of cell viability and significant increase of LDH activity were observed in all experimental hepatocyte cultures after 12, 24 and 36h exposure to alpha-AMA at concentration 2microM. Exposure of the cells to alpha-AMA resulted also in significant reduction of cell spreading and attachment. However, addition of tested antidotes to experimental cultures significantly stimulated cell proliferation and attachment. In cell cultures exposed simultaneously to alpha-AMA and tested antidotes cytotoxic parameters (MTT and LDH) were not significantly different from control incidences. The cytoprotective effect of all antidotes was not dose-related, which reflects a high efficacy of all these substances. Administration of studied antidotes was not associated with any adverse effects in hepatocytes. The administration of ACC, BPCN or SIL to human hepatocyte cultures showed a similar strong protective effect against cell damage in alpha-AMA toxicity.

Failure of benzylpenicillin, N-acetylcysteine and silibinin to reduce alpha-amanitin hepatotoxicity

BACKGROUND

Intoxications caused by amanitin-containing mushrooms represent an unresolved problem in clinical toxicology. The objective of this study was a comparative evaluation of benzylpenicillin (Bp), acetylcysteine (ACC) and silibinin (Sil) efficacy as antidotes in hepatocytes intoxicated with alpha-amanitin (alpha-AMA).

MATERIALS AND METHODS

All experiments were performed on cultured canine hepatocytes. Cytotoxicity evaluation of cultured cells (MTT assay, extracellular lactate dehydrogenase activity) was performed at 12, 24 and 48 h of exposure to alpha-AMA and/or antidotes.

RESULTS

Following 24 and 48 h exposure there was a significant decline of hepatocyte viability and an increase of lactate dehydrogenase activity in groups exposed to alpha-AMA and in groups exposed simultaneously to alpha-AMA and antidotes. Moreover, hepatocyte viability and lactate dehydrogenase activity in all these groups were similar. Administration of studied antidotes without alpha-AMA, was not associated with any adverse effects in hepatocytes.

CONCLUSION

All antidotes tested in this study against alpha-AMA were not effective in canine hepatocyte cultures.

Behavior of silica particles introduced into an isolated rat heart as potential drug carriers

Silica powders consisting of small spherical particles (50-200 nm) have been obtained by the sol-gel method. A suspension of such particles in the Krebs-Hanseleit solution has been introduced into the coronary circulation of a beating perfused rat heart. The influence of the suspension on the heart muscle and the coronary vessels in the rat body has been histopathologically examined. The particles have not left the lumen of the vessels and have not caused any side effects. These observations suggest the possibility of using such silica particles as a carrier for selected drugs.

Effect of aging process on liver function in extracorporeal rat liver perfusion

BACKGROUND/AIMS

Liver function appears to be well maintained in old age. However, the current state of knowledge about liver aging processes is incomplete. In this study, using extracorporeal liver perfusion model, we evaluated the differences between liver function in young and old rats.

METHODOLOGY

Livers were harvested from groups of young (2 months) and old (12 months) rats and perfused for 2 hours with a perfusion fluid. After 10, 30, 60, 90 and 120 minutes of perfusion, glucose concentration as well as enzyme levels (alanine aminotransferase, aspartate aminotransferase and lactic dehydrogenase) were measured. On completion of perfusion all bile produced was collected.

RESULTS

All measured parameters changed significantly as a function of perfusion time in both groups. Changes in enzyme levels were most evident between 90 and 120 minutes of perfusion. In contrast to old rats, where glucose concentration decreased during all time periods of perfusion, in young rats the glucose concentration increased at the beginning of perfusion.

CONCLUSIONS

The results suggest that livers obtained from older rats are damaged to a greater extent and are more susceptible to unfavorable conditions during perfusion than livers obtained from younger rats. Also, single measurement of liver enzymes is not enough for complete liver function assessment.

Isolated heart perfusion according to Langendorff---still viable in the new millennium

The isolated perfused mammalian heart preparation was established in 1897 by Oscar Langendorff. The method was developed on the basis of the isolated perfused frog heart established by Elias Cyon at the Carl Ludwig Institute of Physiology in Leipzig, Germany in 1866. Observations made using both methods at the end of the 19th and at the beginning of the 20th century led to important discoveries, forming the basis for our understanding of heart physiology. This included the role of temperature, oxygen and calcium ions for heart contractile function, the origin of cardiac electrical activity in the atrium, the negative chronotropic effect of vagus stimulation and the chemical transmission of impulses in the vagus nerve by acetylcholine. Langendorff himself demonstrated that the heart receives its nutrients and oxygen from blood via the coronary arteries and that cardiac mechanical function is reflected by changes in the coronary circulation. The method underwent many modifications but its general principle remains the same today. Blood, or more commonly crystalloid perfusates, are delivered into the heart through a cannula inserted in the ascending aorta, either at constant pressure or constant flow. Retrograde flow in the aorta closes the leaflets of the aortic valve and as a consequence, the entire perfusate enters the coronary arteries via the ostia at the aortic root. After passing through the coronary circulation the perfusate drains into the right atrium via the coronary sinus. The simplicity of the isolated mammalian heart preparation, the broad spectrum of measurements which can be done using this method, its high reproducibility and relatively low cost make it a very useful tool in modern cardiovascular and pharmacological research, in spite of a few shortcomings. In the last decade the method has brought many important advances in many areas including ischemia-reperfusion injury, cell-based therapy and donor heart preservation for transplant.

The Influence of prolonged β-blockers treatment on male rabbit's sexual behavior and penile microcirculation

The aim of the study was to assess the effect of the prolonged intake of three beta-blocking drugs (propranolol, metoprolol and nebivolol) on the sexual behavior and penile microcirculation of rabbits. Drugs were administered p.o. for 9 weeks and every three weeks in each group (n=13) one subgroup (n=7) performed behavioral tests, whereas in the second subgroup (n=6) penile microcirculation was measured with a laser Doppler flowmeter. The copulation studies revealed significant impairment of sexual function only in the propranolol treated group. The measured behavioral parameters suggest that at a given dose propranolol affects more performance rather than arousal aspects of rabbits' sexual behavior. In the course of the whole study no significant difference was observed among groups in penile blood flow. The data indicate that among the beta-blockers given only propranolol interferes with sexual behavior, and that beta-blockers do not appear to have a negative effect on penile microcirculation.

The role of calcium and calcium channel blocking drugs in damage to the liver preserved for transplantation

Calcium plays a crucial role in physiological process in liver cells however in high concentrations these ions can be pathogenic and lead to cell death. Mechanisms responsible for maintaining calcium ion concentration gradient in physiological conditions include transmembrane transport, storage in intracellular organelles and binding to cytoplasmatic proteins. Ischemia, sepsis, anoxia and action of toxins are responsible for uncontrolled influx of calcium and consequently cell damage. Liver damage during its preservation for transplantation is connected with dysfunction of many enzymes, damage of cell membrane and cytoskeleton proteins. During reperfusion Kupffer cells are activated, reactive oxygen species are produced and microcirculation is disordered by calcium--dependent processes. Calcium channel blocking (CCB) drugs exhibit immunomodulatory impact and positive interaction with cyclosporine or tacrolismus. They also have cytoprotective properties during preservation end reperfusion time. They seem to improve liver function, decrease liver cell damage, elevate bile production, decrease lipid peroxydation and free radicals production. But in some experiments CCB do not modify calcium concentration. More research on preservation conditions is needed to increase the probability of a successful liver transplantation.

Assessment of efficacy of quercetin-5'-sulfonic acid sodium salt in the treatment of acute chromium poisoning: experimental studies

Hexavalent chromium compounds exhibit higher toxicity than its trivalent compounds since chromium ions in the +6 oxidation state easily cross biological membranes. It has recently been proposed that substances reducing chromium ions from the +6 to the less toxic +3 oxidation state can be beneficial in management of acute chromium poisoning. In vitro studies also demonstrated quercetin-5 '-sulfonic acid sodium salt (NaQSA) to reduce chromium ions from the +6 to the +3 oxidation state. The aim of the study was to determine efficacy of NaQSA in treatment of acute poisoning with a hexavalent chromium compound. The experiment was carried out on male and female Wistar rats which were divided into 4 experimental (A,B,C,D) and control (K) groups. All animals received intragastrically a single CrO3 dose equal to its LD50. Thirty minutes after administration of CrO3, NaQSA was administered intragastrically at a dose of 50 mg/kg (group A) and 100 mg/kg (group B). In groups C and D, NaQSA was administered ip 2 h after administration of CrO3 and then twice a day for 4 days at doses of 50 mg/kg (group C) and 100 mg/kg (group D). Only intragastric administration of NaQSA at a dose of 100 mg/kg decreased mortality in acute poisoning with CrO3. In groups B and D, aminotransferase activity was statistically significantly dropping from day 7 of the experiment in comparison with the group K, which indicates lesser damage to the liver in animals treated with NaQSA. Bilirubin concentrations in groups B and D were also much lower than in the group K, but the difference between average bilirubin levels in these groups and the K was not statistically significant. The results of the study suggest the usefulness of NaQSA in the treatment of poisoning with hexavalent chromium compounds.

Influence of nifedipine, nitrendipine and verapamil at low concentration on antipyrine metabolism examined by extracorporeal rat liver perfusion

An increase in calcium ion concentration in the cytoplasm due to the influence of various toxic agents causes disturbances in the structure and function of hepatocytes, leading to their damage and even death. Calcium ions enter the cell mostly through calcium channels, therefore, it has been suggested that calcium channel inhibitors (CCI) could protect hepatocytes from the action of toxic substances. The present study investigated the effect of the selected CCI (nifedipine, nitrendipine and verapamil) on liver function, measured by the efficiency of oxidation reaction, in this case by determination of the rate of antipyrine metabolism. The experiment was carried out using the method of extracorporeal liver perfusion (ELP). None of the studied CCI applied at a concentration of 50 micromol/l increased the rate of antipyrine metabolism over the whole period of ELP. However, supplementation of perfusion fluid with nifedipine, nitrendipine or verapamil at a concentration of 20 micromol/l considerably improved metabolic liver efficiency during the second hour of perfusion, i.e. at the time, when large number of hepatocytes started to perish, which could indicate protective action of the tested CCI. However, the CCI-induced acceleration of antipyrine metabolism was not a result of their influence on calcium channels, since these drugs block calcium channels, when given at the concentrations as high as 100-400 micromol/l. Moreover, it seems that facilitation of antipyrine metabolism during ELP was not due to their action on microsomal enzymes because CCI were administered at very low concentrations, besides, they are metabolic inhibitors, and not inducers. The present experiment suggests that low concentrations of CCI can exert hepatoprotective effect. However, confirmation of this conclusion requires further studies using other experimental methods.

[Histamine receptors in the female reproductive system. Part I. Role of the mast cells and histamine in female reproductive system]

Histamine isolated from many different tissues, acts via three types of histamine receptors: H1, H2 and H3. In peripheral tissues histamine is mainly stored in mast cells (MC). Presence of mast cells was proved also in mammals' uteri. In human uterus the majority of mast cells are located close to smooth muscle cells. It might indicate that MC plays a role in tissue remodelling during the menstrual cycle. The quantity and activity of mast cells is in connection with hormonal status of the organism. Although there are some differences, human uterine mast cells are similar to the mast cells isolated from other tissues. It is suggested that histamine is important for normal ovulation, blastocyst implantation, placental blood flow regulation, lactation and contractile activity of uterus. Histamine may also play a role in pathological processes such as pre-eclampsia or preterm delivery. The participation of mast cells and histamine in blastocyst implantation is very controversial. In W/Wv mice (without mast cells) normal implantation was observed. It denies the main role of mast cells in this process but dos not exclude histamine action. In mice the major source of histamine are uterine epithelial cells during early pregnancy. The influence of cytokines on blastocyst implantation and the role of histamine in cytokines release from the uterine mast cells are also very unclear.

[Histamine receptors in the female reproductive system. Part II. The role of histamine in the placenta, histamine receptors and the uterus contractility]

The presence of the mast cells was confirmed not only in the uterus but also in the placental tissue. Mediators released from the placental mast cells may play a role in regulation of placental blood flow and normal blood pressure. Processes such uptake and clearance of vasoactive mediators may be upset in those women who developed pre-eclampsia. Histamine released from the placental mast cells may be involved in the mechanisms controlling myometrium contractility during the labour at term and preterm delivery. There is a correlation between the level of placental histamine and presence (or not) uterus contractility. Histamine produce a contractile response in isolated myometrial strips, in the majority of mammals, via H1 histamine receptors activation, but in some species e.g. rat, predominant response of uterus is relaxation (via H2 histamine receptors activation). Predominant response of the human uterus to histamine is contraction. Relaxation of human myometrial strips may be evoked after earlier usage of H1 receptors antagonists, although some H2 receptors agonists (e.g. dimaprit) induce the relaxation of human uterus without H1 receptors antagonists. Myometrium contractile activity is under control of sexual hormones. Neither the presence of H3 histamine receptors on the human myometrial smooth cells nor its role in the female reproductive system regulation was proved. Lack of the functional H3 receptors either on the smooth muscle cells or neuronal components of the animals' myometrium was shown in some studies.

Betahistine inhibits food intake in rats

Betahistine, administered intraperitoneally, decreased, in a dose-dependent manner and in a statistically significant degree, total food intake in different experimental models in rats.

Synthesis and pharmacological properties of new derivatives of 4-methyl-5-oxalo-1H-2,3,4,5-tetrahydro-1,5-benzodiazepin-2-one and beta-oxo-5-(4-methyl-1H-2,3,4,5-tetrahydro-1,5-benzodiazepin-2 -one)propionic acid

5-Ethoxalyl 4-methyl-1H-2,3,4,5-tetrahydro 1,5-benzodiazepin-2 -one [I] and 5-ethoxymalonyl-4-methyl-1H-2,3,4,5-tetrahydro-1,5-benzodiazepi n-2-one [IV] were subjected to transesterification using alcohols (propanol, butanol, pentanol) giving derivatives II-IV, VII, VIII. The derivatives I and VI were caused to undergo ammonolysis giving 4-methyl-5-oxamoyl-1H-2,3,4,5 tetrahydro 1,5-benzodiazepin-2-one [V] and 5-malonamoyl-4-methyl-1H-2,3,4,5-tetrahydro-1,5-benzodiazepin++ +-2-one [IX]. The compounds I-IX were tested towards their psychotropic activity. The preparates I, III and V had an anxiolytic action in the four-plate test. The anxiolytic properties of the compound V were confirmed in the test of the black-white box. The antagonism of all investigated compounds for toward reserpine, first of all of the preparations III, IV, V and IX, indicates an antidepressive activity dependent on a stimulation of the adrenergic system.

[The effect of cimetidine and famotidine on esophageal motility]

An effect of cimetidine and famotidine on the lower esophagus sphincter pressure and esophageal body motility has been investigated. The studies involved 30 patients with duodenal ulcer. The lower esophagus sphincter pressure, mean force and mean duration of spasms as well as wave transmission velocity in esophageal body, 1-13 cm above the sphincter, have been recorded with Polyphysiograph R-611. The lower esophagus sphincter pressure and esophageal body motility have been recorded 15 minutes prior to and following the administration of 200 mg cimetidine or 20 mg famotidine. It was shown that cimetidine has net changed the lower esophagus sphincter pressure and esophageal body motility parameters. Famotidine increased the lower esophagus sphincter pressure from the initial 2.31 +/- 1.19 kPa to 3.51 +/- 1.61 kPa (p < 0.05) and had no effect on the esophageal body motility parameters. It may be concluded that within H2-receptor antagonists famotidine may be considered a drug of choice in the treatment of gastroesophageal reflux.

Synthesis and pharmacological properties of derivatives of isoxazolo[4,3-d]pyrimidine. III

Synthesis of new isoxazolo[4,5-d]pyrimidine derivatives is reported. Some of isoxazolo[4,5-d]pyrimidine derivatives were tested for anticonvulsant, anxiolytic and antiserotonine activity. Compounds 14 and 16 proved active against hypothermia induced by reserpine and hyperthermia induced by m-CPP.

Synthesis and properties of 4-substituted-1-piperazinyl-propyl derivatives of 1-phenyl-7-methylpyrimido-[4,5-d]pyrimidin-4-one

In reactions of 1-phenyl-7-methyl-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimido[ 4,5-d]pyrimidin e (1) with 1-(3-chloropropyl)-4-methyl(phenyl, 3-chlorophenyl, 2-pyrimidynyl, 2-thiazolyl)piperazines (5), mixtures of isomeric N- and S-substituted derivatives of compound 1 (3 and 4) were obtained. Isomers were separated by fractional crystallization. The structure of novel compounds 3 and 4 was confirmed by elemental and spectral analyses. In pharmacological screening compounds 3b and 4b displayed rather strong analgesic action, inhibited amphetamine hyperactivity and abolished apomorphine stereotypy. Compounds 3e,3d and 4e attenuated m-chlorophenylpiperazine-induced hypothermia.

Synthesis and preliminary pharmacological investigation of the central action of derivatives of 3-aminomethyl-5-(p-chlorophenyl)-tetrahydrofuran-2-one and 2-aminomethyl-4-(p-chlorophenyl)-4-hydroxybutyric acid

Using 3-cyano-5-(p-chlorophenyl)-tetrahydrofuran-2-one 4, 3-aminomethyl derivatives of 5-(p-chlorophenyl)-tetrahydrofuran-2-one were synthesized. The starting material under alkaline hydrolysis yielded 5-(p-chlorophenyl)-tetrahydrofuran-2-one-3-carboxylic acid 5, which was transformed, via an acid chloride, into amide 6. From acid 5 by aminomethylation compounds 7-12 were obtained. Some of them (7, 8, 12) in reactions of ammono-, amino-, and hydrazinolysis yielded corresponding derivatives of 2-aminomethyl-4-(p-chlorophenyl)-4-hydroxybutyric acid 13-20. In pharmacological tests compounds 10 displayed analgesic activity while compounds 2 and 3 revealed anxiolytic properties.

Acyl derivatives of 1,5-benzodiazepines. III. Acyl derivatives of ethyl ester of 4-methyl-1H-tetrahydro-1,5-benzodiazepine-2-carboxylic acid

Two series of derivatives of ethyl ester of 4-methyl-1H-tetrahydro-1,5-benzodiazepine-2-carboxylic acid (1) have been synthesized. The acetyl derivative (2) of ester 1 in preliminary pharmacological screening showed analgesic activity in the "writhing" test and the benzoyl derivative (5) exhibited antianxiety properties in the four plate test, while N,N-disubstituted aminoacetyl derivatives of 1 showed analgesic and anticonvulsant activity (10).

Synthesis and preliminary pharmacological studies on dihydropyrido-1,3,4-triazepinone derivatives

New 4,5-dihydropyrido-[2,3-e]-1,3,4-triazepin-5-one derivatives (2-9) were synthesized. The preliminary pharmacological tests revealed antinociceptive action of compounds 4-7 and 9 and antianxiety action of compound 4.