Once initiated, how does toxic tissue injury expand?

Once initiated, how tissue injury expands after high toxicant doses, even after their complete elimination, is not understood. Free-radical generation was initially proposed to mediate progression of injury. However, mechanisms proposed thus far have remained unsubstantiated. Necrotic injury is characterized by loss of osmoregulation, cell swelling, blebbing, and cell rupture. This exposes cytosolic enzymes, including proteases, phospholipases, and lysosomal Ca(2+)-dependent enzymes, to high extracellular calcium (Ca(2+)). Activated hydrolytic enzymes, termed 'death proteins,' hydrolyze their substrates in the plasma membrane of neighboring cells, commencing self-perpetuated injury progression. Likewise, ischemia-reperfusion injury exposes the hydrolytic enzymes to high Ca(2+), fuelling the progression of tissue injury. This mechanism is independent of the offending toxicant that initiates the injury. I present here a case for therapeutic intervention with inhibitors directed against death proteins as a means to avert organ failure and death well after the poisoning event.     

Limbic system as immune tissue

The purpose of this review is to examine the interaction of the limbic system and the cellular immune system from the perspective of evolutionary biology. While the limbic system exerts a level of control over the stress response systems, the cellular immune system spearheaded by the monocyte-macrophage is responsible for the acute phase response to threat.The potential role of the macrophage in certain neuropsychiatric and psychosomatic disorders,including dementia,delirium, schizophrenia, depression and autoimmune disease will be     

Effects of a hydroxylated metabolite of the β-adrenoreceptor antagonist,carvedilol, on post-ischaemic splanchnic tissue injury

1. Reactive oxygen species have been demonstrated to play a critical role in post-ischaemic tissue injury. The present experiment was designed to evaluate the effects of SB 211475, a hydroxylated metabolite of the new β-adrenoceptor antagonist, carvedilol, on rat splanchnic ischaemia (SI, 60 min) and reperfusion(R)-induced shock and tissue injury.
2. Administration of SB 211475 two min before R attenuated SI/R injury in a dose-dependent manner. At doses of 0.5 mg kg⁻¹ and 1.0 mg kg⁻¹, SB 211475 exerted significant anti-shock and endothelial protective effects, characterized by prolonged survival times, increased survival rates, attenuated increases in tissue myeloperoxidase activity and haematocrits, and preserved endothelium-dependent vasorelaxation.
3. Administration of 1 mg kg⁻¹ carvedilol attenuated shock-induced tissue injury and endothelial dysfunction. However, administration of 0.5 mg kg⁻¹ carvedilol had no protective effects on post-ischaemic tissue injury.
4. Previous studies have shown that SB 211475 has virtually no β-blocking activity but possesses more potent antioxidant activity than carvedilol. In the present study, SB 211475 exerted more potent protective effects than the parent compound, suggesting that this metabolite of carvedilol is superior to carvedilol with regard to its protection against post-ischaemia tissue injury.

     

β-Adrenergic receptors in guinea-pig myocardial tissue

Summary Stereospecific binding sites for (–) [³H]-alprenolol, a -adrenergic antagonist, have been identified in guinea-pig myocardial broken cell preparations. The concentration of the sites was 0.3 pmoles per mg of protein and the dissociation constant (at 37°C) 10^–8 M. A close correlation between the ability of various -adrenergic antagonists to compete with tracer alprenolol binding and to block the response of isoprenaline-stimulated myocardial adenylate cyclase has been found. Low affinity sites for the labelled -adrenergic antagonist in contrast to stereospecific sites are heat stable and do not discriminate between the (–) and the (+) forms of the -adrenergic antagonists. Adenylate cyclase in guineapig myocardial tissue is poorly stimulated by isoprenaline or 5-guanylylimidodiphosphate. This is attributed to a high basal activity which could be lowered by a preincubation at 37°C.     

About coffee, cappuccino and connective tissue growth factor-Or how to protect your liver!?

Several epidemiological studies suggest that coffee drinking is inversely correlated with the risk of development of liver fibrosis. However, a causal, mechanistic explanation has long been pending. New results indicate that the methylxanthine caffeine, major component of coffee and the most widely consumed pharmacologically active substance in the world, might be responsible for this phenomenon as it, and even more potently its derived primary metabolite paraxanthine, inhibits transforming growth factor (TGF)-β-dependent and -independent synthesis of connective tissue growth factor (CTGF/CCN2) in liver parenchymal cells in vitro and in vivo. CTGF plays a crucial role in the fibrotic remodeling of various organs which has therefore frequently been proposed as therapeutic target in the management of fibrotic disorders. This article summarizes the clinical-epidemiological observations as well as the pathophysiological background of the antifibrotic effects of coffee consumption and provides suggestions for the therapeutic use of caffeine and its derived metabolic methylxanthines as potentially powerful drugs in patients with chronic fibrogenic liver disease by their inhibitory effect on (hepatocellular) CTGF synthesis.     

Absorption and distribution of etoricoxib in plasma, CSF, and wound tissue in patients following hip surgery—a pilot study

The perioperative administration of selective cyclooxygenase-2 (COX-2)-inhibitors to avoid postoperative pain is an attractive option: they show favorable gastro-intestinal tolerability, lack inhibition of blood coagulation, and carry a low risk of asthmatic attacks. The purpose of this study was to determine the cerebrospinal fluid (CSF), plasma, and tissue pharmacokinetics of orally administered etoricoxib and to compare it with effect data, i.e., COX-2-inhibition in patients after hip surgery. The study was performed in a blinded, randomized, parallel group design. A total of 12 adult patients were included who received 120 mg etoricoxib (n?=?8) or placebo (n?=?4) on day 1 post-surgery. Samples from plasma, CSF, and tissue exudates were collected over a period of 24 h post-dosing and analyzed for etoricoxib and prostaglandin E₂ (PGE₂) using liquid chromatography-tandem mass spectrometry and immuno-assay techniques. CSF area under the curve (AUC) [AUCs_(O–24h)] for etoricoxib amounted to about 5% of the total AUC in plasma (range: 2–7%). Individual CSF lag times with respect to (50%) peak plasma concentration were ≤2 h in all but one case (median: 1 h). PGE₂ production in tissue was significantly blocked by the COX-2 inhibitor starting with the appearance of etoricoxib in tissue and lasting for the whole observation period of 24 h (P?<?0.01). In conclusion, etoricoxib reaches the CSF and site of surgery at effective concentrations and reduces PGE₂ production at the presumed site of action.     

Encapsulation, pharmacokinetics and tissue distribution of interferon ��-2b liposomes after intramuscular injection to rats

The aim of the present study was to investigate the effect of liposome-encapsulation and liposome-size on the in vivo pharmacokinetics of interferon α-2b (IFNα-2b) following i.m. administration to rats, and whether there was any liver-targeting of these liposomes. Since liposomes of different sizes can be obtained by homogenization, the effect of homogenization on the IFNα-2b activity was also investigated. The pharmacokinetics of IFNα-2b solution (12.8 μg/kg) and IFNα-2b prepared in liposomes, including three mean sizes of 172 nm (12.2 μg/kg), 113 nm (44.2, 11.0, and 2.8 μg/kg, respectively), and 82 nm (13.1μg/kg), were studied after a single i.m. dose to rats. Compared to a solution of IFNα-2b. administration of liposomal IFNα-2b resulted in a significantly prolonged t(max), the apparent elimination half life (t(1/2β)) was 2.3 times longer, both AUC(0-∞) and MRT(0-∞) were also clearly enhanced and greater accumulation was obtained in the liver (p < 0.05). The AUC(0-∞) increased proportionally to the administered dose of IFNα-2b liposomes. Moreover, the size of liposomes ranging from 82 nm to 172 nm had no significant difference on the pharmacokinetic behavior in vivo (p > 0.05). In sum, compared with the free form, IFNα-2b encapsulated in liposomes can alter strikingly the pharmacokinetics properties following i.m. injection and if a liposomal size ranging from 82 nm to 172 nm was used, consistent pharmacokinetic behaviors of IFNα-2b was exhibited. The liposomal formulation apparently targeted the liver, offering a potential advantage for hepatitis B treatment.     

Synergistic antinociceptive effects of anandamide, an endocannabinoid, and nonsteroidal anti-inflammatory drugs in peripheral tissue: a role for endogenous fatty-acid ethanolamides?

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit fatty-acid amide hydrolase (FAAH), the enzyme responsible for the metabolism of anandamide, an endocannabinoid. It has been suggested that the mechanisms of action of NSAIDs could be due to inhibition of cyclooxygenase (COX) and also to an increase in endocannabinoid concentrations. In a previous study we have demonstrated that the local analgesic interaction between anandamide and ibuprofen (a non-specific COX inhibitor) was synergistic for the acute and inflammatory phases of the formalin test. To test this hypothesis further, we repeated similar experiments with rofecoxib (a selective COX-2 inhibitor) and also measured the local concentrations of anandamide, and of two fatty-acid amides, oleoylethanolamide and palmitoylethanolamide. We established the ED(50) for anandamide (34.52 pmol+/-17.26) and rofecoxib (381.72 pmol+/-190.86) and showed that the analgesic effect of the combination was synergistic. We also found that paw tissue levels of anandamide, oleoylethanolamide and palmitoylethanolamide were significantly higher when anandamide was combined with NSAIDs and that this effect was greater with rofecoxib. In conclusion, local injection of anandamide or rofecoxib was antinociceptive in a test of acute and inflammatory pain and the combination of anandamide with rofecoxib was synergistic. Finally, locally injected anandamide with either NSAID (ibuprofen or rofecoxib) generates higher amount of fatty-acid ethanolamides. The exact comprehension of the mechanisms involved needs further investigation.     

Erythropoietin regulates apoptosis, inflammation and tissue remodelling via caspase-3 and IL-1β in isolated hemoperfused kidneys

Ischemia reperfusion injury associated with apoptosis and inflammation plays crucial roles in renal transplantation. Erythropoietin provides renoprotection, but its effects and mechanisms on kidney preservation are not fully defined. Porcine kidneys, subjected to 10 min warm ischemia, underwent 16 h cold storage followed by 2 h normothermic hemoperfusion with or without 5000 units/L erythropoietin. Apoptotic cells were increased in tubular lumens and interstitial areas by normothermic perfusion alone, but decreased in tubular areas by additional erythropoietin. Myeloperoxidase+ cells, free cells and cell debris in tubular lumens were gradually increased by cold storage, normothermic perfusion and erythropoietin in normothermic perfusion. Accordingly, caspase-3 activity as well as its active proteins was increased by normothermic perfusion and furthered by erythropoietin. In contrast, macrophage L1 protein positive cells in tubulointerstitial areas, cytokine interleukin (IL)-1β activation, tubular dilation and vacuolation were raised by normothermic perfusion, but all alleviated by erythropoietin, with higher urine output. The migration of myeloperoxidase+ cells with apoptotic features and apoptotic cells with polymorphous nuclei from tubulointerstitial areas into tubular lumens was widely displayed in the kidneys, especially those preserved by erythropoietin in normothermic perfusion. HSP70 protein was enhanced by normothermic perfusion regardless of erythropoietin. In addition, erythropoietin induced a dose-dependent increase in caspase-3 precursor in porcine proximal tubular cells (LLC-PK1) and also stimulated caspase-3 cleavage in cisplatin-treated cells. In conclusion, erythropoietin promotes inflammatory cell apoptosis, drives inflammatory and apoptotic cells into tubular lumens, eventually leads to inflammation clearance, renoprotection and tissue remodelling through caspase-3 and IL-1β in isolated haemoperfused kidneys.     

17β estradiol induced ROS generation,DNA damage and enzymatic responses in the hepatic tissue of Japanese sea bass

The importance of endocrine disrupting chemicals and their effects on fish has been documented in recent years. However, little is known about whether the estrogenic compound 17β estradiol (E2) causes oxidative stress in the hepatic tissue of fish. Therefore, this work tested the hypothesis that E2 might cause oxidative stress in the Japanese sea bass Lateolabrax japonicus liver. To test this hypothesis, its effects on reactive oxygen species (ROS) production, DNA damage, antioxidants and biotransformation enzyme were investigated in two different size groups (fingerling and juvenile groups) following 30 days exposure. Results showed that there was a good relationship between the E2 exposure concentration, plasma E2 level and ROS generation. In addition ROS production correlated negatively with 7-ethoxyresorufin-O-deethylase activity and positively with DNA damage and lipid peroxidation (LPO). Antioxidant enzymes such as superoxide dismutase and catalase did not show any significant relation with ROS, LPO and DNA damage. In contrast, glutathione mediated enzymes showed a good relationship with the above parameters suggesting that the glutathione system in fish might be responsible for protection against the impact of E2 and also indicating a possible adaptive response during exposure periods. In addition, it was observed that fingerling was more susceptible to E2 exposure than juvenile fish. The present study provided strong evidence that the ROS level increased significantly in the liver of E2 exposed fish, and that ROS might serve as a biomarker to indicate estrogen contamination.     

Effects of carnosine on prooxidant–antioxidant status in heart tissue,plasma and erythrocytes of rats with isoproterenol-induced myocardial infarction

Rats were injected with isoproterenol (ISO; 110 mg/kg, ip, 2 doses, 24 h interval) to induce acute myocardial infarction (AMI) and were sacrificed 6 and 24 h after the last ISO injection. The heart tissue, plasma and erythrocytes of these rats were evaluated for cardiac markers and oxidative stress parameters. Levels of cardiac troponin T (cTnT) and the activities of creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) in plasma were increased 6 and 24 h after ISO treatment. The levels of malondialdehyde (MDA), diene conjugate (DC), and protein carbonyl (PC) were increased in heart tissue and plasma, while levels of erythrocyte MDA and glutathione (GSH) and plasma ferric reducing antioxidant power (FRAP) were also increased. However, GSH levels and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) decreased in heart tissue of rats with AMI. We also investigated the effects of carnosine (CAR) treatment on these parameters 24 h after the last ISO injection. CAR (250 mg/kg/day; ip) treatments were carried out either 10 days before ISO injection or 2 days concomitant with ISO. Pretreatment with CAR decreased plasma LDH and AST activities and ameliorated cardiac histopathological changes in ISO-treated rats. Cardiac MDA, DC and PC levels decreased, but GSH levels and SOD and GSH-Px activities increased. However, the increases in plasma MDA and PC levels as well as erythrocyte H₂O₂-induced MDA and GSH levels did not change due to CAR pretreatment. In conclusion, our findings indicate that CAR pretreatment may have protective effects on ISO-induced cardiac toxicity by decreasing oxidative stress.     

Bone tissue engineering - a field for new medicinal products?

It was only in December 2008 that the European Union regulated the approval procedure for tissue engineered products (TEPs). Due to this regulation, TEP is classified as an advanced therapy medicinal product and as such may be recognized as a tool in pharmaceutical biotechnology. This paper gives a short review of the concept, the experimental evaluation and the clinical potency of tissue engineering (TE), with a particular focus on bone tissue engineered products. After a period of great enthusiasm about TE at the end of the 20th century a slight disappointment followed in the early 2000s. The review refers also to the continuously growing scientific interest, accompanied by the still modest representation of TEPs on the medical market. Some remarks are given on a bench-to-clinic road, including criticism concerning data originating from animal experiments. An attempt is made to foresee the still promising future of bone tissue engineered products (BTEPs) in practical use.     

The combined effects of TGF-β, IGF and PDGF on 5α-reductase activity on androgen substrates in human gingival tissue

The combined effects of the grwoth factors, PDGF, TGF-β and IGF, on the metabolism of two androgen substrates by human gingival tissue were investigated. Having established their wet weight, duplicate incubations were performed in Eagle's MEM using [¹⁴C]testosterone/[¹⁴C]4-androstenedione as substrates and growth factors, PDGF, TGF-β and IGF, alone and in combination. Steroid metabolites were then isolated, separated and quantified, using a radioisotope scanner. With [¹⁴C]testosterone as substrate, there were 3–5-fold decreases in 5α-reductase activity in response to individual growth factors, while the combinations, PDGF+TGF-β, PDGF+IGF and TGF-β-IGF, resulted in approximately half the stimulation, or similar to that of one of the growth factors, but still about 2-fold greater than control values. When [¹⁴C]4-androstenedione was used as substrate, there were approximately 2–6-fold increases in DHT synthesis in response to the growth factors alone. When used in combination, and intermediate response was seen. Growth factor combinations can enhance anabolic activity in the chronically inflamed periodontium.     

Plasma pharmacokinetics,tissue distribution and excretion study of 6-gingerol in rat by liquid chromatography–electrospray ionization time-of-flight mass spectrometry

A rapid resolution liquid chromatography coupled with electrospray ionization (ESI) time-of-flight mass spectrometry method was developed and validated for quantitative analysis of 6-gingerol in plasma and various tissues. Liquid–liquid extraction was employed as sample preparation technique. Biological samples were separated on an Agilent Zorbax StableBond-C₁₈ column (4.6 mm × 50 mm, 1.8 μm) and detected by TOF/MS with electrospray ionization (ESI) interface in positive ion mode. Calibration curves (1/x² weighted) offered satisfactory linearity (r² > 0.995) within the test range. The lower limit of quantification in different matrices was in a range of 10–100 ng/mL. Inter- and intra-day precision were in the range of 0.91–11.90% and 0.75–10.23%, respectively. Recoveries in plasma, urine and tissues ranged from 72.5% to 90.4%. Glucuronide of 6-gingerol, the major metabolite of 6-gingerol, was further determined after β-glucuronidase hydrolyzation. This developed method was successfully applied to pharmacokinetics, tissue distribution and excretion studies of 6-gingerol after oral or intraperitoneal administration in rats.     

Comparison of cloned and pharmacologically defined rat tissue α1-adrenoceptor subtypes

Multiple ₁-adrenoceptor subtypes have been defined by pharmacological and receptor cloning techniques, but the precise alignment of cloned and pharmacologically-defined subtypes is still unclear. We have compared the affinities of 8 subtype-selective compounds at three cloned ₁-adrenoceptor subtypes (rat _1B, bovine _1C rat _1A/D) with those previously determined by the same methods in rat spleen, cerebral cortex, and kidney (Naunyn-Schmiedeberg's Arch. Pharmacol. 348: 385–395, 1993). Among all compounds tested to date at cloned ₁-adrenoceptor subtypes (+)-tamsulosin appears to be the most selective with a rank order of potency _1C > _{1A/D 1B}. Affinities for the _1A-selective 5-methyl-urapidil, methoxamine, oxymetazoline, phentolamine and (–)- and (+)-tamsulosin and for noradrenaline and SDZ NVI-085 at the splenic _1B-adrenoceptors and at their low affinity sites in cerebral cortex and kidney correlated best with those at the cloned _1B-adrenoceptor. Affinities of these drugs at their high affinity sites in cerebral cortex (pharmacologically-defined _1A-adrenoceptor) were matched best by those at the cloned _1C-adrenoceptor. Rat kidney appears to contain two chloroethylclonidine-resistant ₁-adrenoceptor subtypes one of which is similar to the cloned at _1C- and one to the cloned _1A/D-adrenoceptor. We conclude that the cloned _1B-adrenoceptor is the genetic correlate of the pharmacologically-defined _1B-adrenoceptor. An ₁-adrenoceptor subtype corresponding to the cloned _1A/D-adrenoceptor appears to exist in rat kidney. Among cloned ₁-adrenoceptor subtypes, the bovine _1C-adrenoceptor bears the closest resemblance to the pharmacologically-defined _1A-adrenoceptor in rat cortex and to one of the chloroethylclonidine-insensitive subtypes in rat kidney.     

Chitosan-thioglycolic acid conjugate: a new scaffold material for tissue engineering?

It was the aim of this study to evaluate chitosan-thioglycolic acid (chitosan-TGA) conjugate as scaffold material in tissue engineering. Chitosan was modified by the introduction of thiol groups. Briefly, TGA was introduced to chitosan via amide bond formation mediated by a carbodiimide. The properties of the resulting polymer were thereby altered in regard to water solubility, mucoadhesion, biodegradability and in situ gelling compared to the original polymer. Due to the immobilised thiol groups (240+/-30 micromol thiol groups per gram polymer), the viscosity of a 1.5% chitosan-TGA solution was improved 4.3-fold. This can be explained by the formation of disulphide bonds within this polymeric network. The conjugate was tested as scaffold material in form of a gel and sheets. Furthermore, the influence of the thiol groups on the viability of L-929 mouse fibroblasts was evaluated. It was shown that the L-929 mouse fibroblasts grew on both scaffolds despite the thiol groups, although the different surface conditions seemed to have an influence on the growing rate. Chitosan-TGA sheets seemed to be the more preferred layer. The improved in situ gelling may be important for ongoing developments. Direct injectable matrices at the site of tissue damage mimicking the tissue being restored may be a future trend on this topic. Hence, chitosan-TGA is a promising candidate as scaffold material in tissue engineering.     

Application of a liquid chromatography–tandem mass spectrometry method to the pharmacokinetics,bioavailability and tissue distribution of neohesperidin dihydrochalcone in rats

Abstract

1.?This study was aimed at developing a high sensitive and selective liquid chromatography–tandem mass spectrometry method to quantify neohesperidin dihydrochalcone (NHDC) in rat plasma and tissues for pharmacokinetic, bioavailability and tissue distribution studies.

2.?Biological samples were processed with one-step protein precipitation. Rutin was chosen as the internal standard (IS). Chromatographical separation was achieved on an SB-C₁₈ (2.1?mm×?150?mm, 5?μm) column with acetonitrile--0.1% formic acid in water as the mobile phase with gradient elution. Electrospray ionization (ESI) source was applied and operated in negative ion mode; selected ion monitoring mode was used for quantification using target fragment ions m/z 611.4 for NHDC and m/z 609.1 for IS.

3.?Calibration plots were linear over the range of 10–3000?ng/mL for NHDC. Lower limit of quantification (LLOQ) for NHDC was 10?ng/mL. Mean recovery of NHDC from plasma and tissues was better than 80.3%. Coefficient of variation of intra-day and inter-day precision were both less than 15%. The bioavailability of NHDC was 21.8%.

4.?In conclusion, a sensitive, simple and specific LC-ESI-MS method for the determination of NHDC in rat biological samples was developed. This developed method is successfully used in the pharmacokinetic and tissue distribution study of NHDC in rats.