A Chronic Ocular-Hypertensive Rat Model induced by Injection of the Sclerosant Agent Polidocanol in the Aqueous Humor Outflow Pathway.

BACKGROUND: To induce a moderate chronic ocular hypertension (OHT) by injecting polidocanol, a foamed sclerosant drug, in the aqueous humor outflow pathway. METHODS: Intraocular pressure (IOP) was monitored for up to 6 months. Pattern and full-field electroretinogram (PERG and ERG) were recorded and retinal ganglion cells (RGC) and retinal nerve fiber layer (RNFL) thickness were assessed in vivo with optical coherence tomography (OCT) and ex vivo using Brn3a immunohistochemistry. RESULTS: In the first 3 weeks post-injection, a significant IOP elevation was observed in the treated eyes (18.47 ± 3.36 mmHg) when compared with the control fellow eyes (12.52 ± 2.84 mmHg) (p < 0.05). At 8 weeks, 65% (11/17) of intervention eyes had developed an IOP increase >25% over the baseline. PERG responses were seen to be significantly reduced in the hypertensive eyes (2.25 ± 0.24 µV) compared to control eyes (1.44 ± 0.19 µV) (p < 0.01) at week 3, whereas the ERG components (photoreceptor a-wave and bipolar cell b-wave) remained unaltered. By week 24, RNFL thinning and cell loss in the ganglion cell layer was first detected (2/13, 15.3%) as assessed by OCT and light microscopy. CONCLUSIONS: This novel OHT rat model, with moderate levels of chronically elevated IOP, and abnormal PERG shows selective functional impairment of RGC.

A novel porcine model for chemically inducible Crohn's-like reaction.

BACKGROUND: New animal models provide insights into the pathogenesis of different types of inflammatory bowel disease as well as novel pathways for new therapeutic options. However, the scarcity of large animal models hinders the research and development of new surgical procedures and technological devices in inflammatory bowel disease surgery. Common small animal inducible models involve chemical agents that result in the development of acute intestinal inflammation. OBJECTIVES: To assess a novel method for the induction of Crohn's-like colitis using intramural injection of sclerosants in a porcine model. METHODS: Seven domestic pigs underwent several experimental protocols to assess the efficacy of intramural colonic injections of two different compounds (lauromacrogol, and phenol in almond oil).Twenty-five different large bowel segments were treated with intramural injections of the compounds. The animals were followed for 6 weeks, and treated colonic segments were resected for histopathological examination. RESULTS: Intramural injection of lauromacrogol resulted in non-specific, mild reactive foreign body changes only. Injection of various dosages of 5% phenol in almond oil caused a range of histopathological changes varying from focal fibrosis to Crohn's-like reactions com rising acute and chronic infiltrates, mucosal ulceration and focal necrosis with enteric and lymphoid non-caseating granulomas. CONCLUSIONS: Intramural colonic phenol in almond oil injection in pigs induces inflammatory reactions that histologically resemble Crohn's disease in humans.

The impact of chemical synovectomy with sodium morrhuate on human chondrocytes and cartilage in vitro.

The vessel sclerosing property of sodium morrhuate is useful in treatment of recurrent joint effusions particularly in cases of knee joint effusions. It also can be employed as an addition to surgical synovectomy. Little is known about the effects of this drug on cartilage. This study was designed to investigate the cytotoxic impact of sodium morrhuate on human chondrocytes and cartilage tissue in vitro. Primary chondrocytes from 13 patients were isolated and cultivated in three-dimensional alginate cultures. Furthermore, femoral cartilage explants of 10 patients were cultivated in vitro. Both chondrocytes and cartilage explants were exposed to mixture of sodium morrhuate and mepivacaine in different concentrations simulating chemical synovectomy. After 48 h, cell proliferation, viability, and cytotoxicity were measured. The cartilage specimens were analyzed for apoptosis by immunohistochemistry. Up to a dilution of 1:600, cells were found to be 100 % viable with a proliferation rate of 74 % compared to controls. From 1:400 onwards, a significant increase in LDH release was measured which reached at dilution of 1:200 74 % of high control, whereas histological examination showed no proof of apoptosis or necrosis in cartilage tissue. The results of this in vitro study demonstrate that the cytotoxic effects of sodium morrhuate on human chondrocytes, which lack their original extracellular matrix, manifest between dilutions of 1:500 and 1:400 and increase with higher concentrations of the drug. This effect was not found for cartilage explants, though.

Evaluation of the minimum effective concentration of foam sclerosant in an ex-vivo study.

BACKGROUND: Foam sclerosants are widely used in sclerotherapy and have been accepted as more effective than the liquid form; however, there is no consensus about the most applicable and effective concentration. OBJECTIVE: The aim of this study was to investigate the histopathological changes caused by various widely used concentrations of foam sclerosant. METHODS: Fifty-six varicose vein segments of 5-10 mm diameter were gently resected and exposed to various concentrations of foam sclerosant (0.5%, 1%, 2%, 3%) for 5 min, and were then prepared for routine histopathological examination. A total damage scoring system, including the presence of endothelial swelling, intimal thickening, cellular vacuolization in the muscle layer, edema in the tunica media and extent of necrosis, was established. RESULTS: The total damage score of the foam sclerosant groups was significantly higher than that of the control group (median 2.75 vs 1, p = 0.007). The highest damage score was achieved by 1% and 2% foam sclerosants (3.5 and 2.5). No significant difference was found among the different concentrations of sclerosant, although the 1% group caused more severe damage at a near significant level (p = 0.074). CONCLUSION: Significant pathological damage can be caused by even the lowest doses of foam sclerosant. The most injurious concentrations were found to be 1% and 2%, morphologically. A working concentration of 1% could thus be preferable to 0.5%, especially in larger veins. Further in-vivo studies are needed in order to validate these findings.

Does Sericin, as a Novel Pleurodesis Agent, Have Higher Effectiveness Compared to Talcum Powder, Doxycycline, and Silver Nitrate Pleurodesis?

INTRODUCTION: The usefulness of sericin as pleurodesis agent has previously been described. Present study aims to compare sericin pleurodesis regarding success, effectiveness, tolerability, and side-effects. METHODS: Adult, 12-week-old Wistar-albino rats (n=60), divided to five groups as sericin, talcum-powder, doxycycline, silver-nitrate and control. Agents were administrated through left thoracotomy, rats sacrificed twelve-days after. RESULTS: Highest ratio of collagen fibers was observed in sericin group, and the intensity was higher than talcum-powder group (p<0.05). Compared to silver nitrate, sericin group displayed better mesothelial reaction, and multi-layer mesothelium was also better (p<0.05). Foreign body reaction and emphysema were less frequent in sericin group (p<0.05). The presence of biological tissue in parenchyma was less prominent in sericin group (p<0.05). Foreign body reaction on thoracic wall was less common in sericin group (p<0.05). Presence of biological tissue glue in thoracic wall was less prominent in sericin group (p<0.05). Glomerular degeneration was lower in sericin group compared to the silver nitrate group (p<0.05), and tubular degeneration was less common in sericin group than talcum group (p<0.05). Pericarditis was less common in sericin group compared to the other groups (p<0.05). CONCLUSION: As an intrinsic, natural glue protein, sericin protects the lung parenchyma and tissues, and its glue-like characteristics enable pleurodesis. The success of sericin in pleurodesis was demonstrated in the present study based on investigations of the pleurae. Being cost-effective and better tolerated agent associated with a low potential of side effects, sericin is more effective, less expensive and provides more lung parenchyma protection.

The lytic effects of detergent sclerosants on erythrocytes, platelets, endothelial cells and microparticles are attenuated by albumin and other plasma components in vitro.

OBJECTIVE: To investigate the lytic effects of sodium tetradecyl sulphate (STS) and polidocanol (POL) on erythrocytes, platelets, endothelial cells and platelet-derived microparticle (PDMP) formation in vitro and the potential protective effects of serum albumin and agents such as procaine. MATERIALS AND METHODS: The effects of sclerosants were studied in blood samples obtained from normal individuals. Absorbance densitometry was used to assess the lytic effects of sclerosants on blood cells and cultured human microvascular endothelial cells (HMEC) in plasma and in saline. PDMP were quantified by flow cytometry. RESULTS: Haemolysis occurred in whole blood at sclerosant concentrations greater than 0.25% for STS and above 0.45% for POL. Similar concentrations of both agents caused platelet and endothelial cell lysis. Both sclerosants released PDMP at low concentrations but destroyed PDMP at higher concentrations. Albumin significantly reduced the lytic effect of both sclerosants on all cells but had a greater inhibitory effect on POL. Protamine at 0.01% had a neutralising effect on STS, whereas procaine and lignocaine showed no such activity. CONCLUSIONS: Sclerosants at therapeutic concentrations lyse blood cells and endothelial cells in vitro. This effect is strongly reduced by serum albumin possibly contributing towards the low incidence of thromboembolic complications of sclerotherapy.

Comparison of silver nitrate and tetracycline as pleural sclerosing agents in rabbits.

The ideal agent to produce pleurodesis has not been identified. Tetracycline, the drug used most commonly in the 1980s, is no longer available. Talc either aerosolized or in a slurry is the agent used just most commonly at the present time, but there are concerns about its safety. Another possibility is silver nitrate, which was widely used in the past, but was abandoned on account of side effects. We hypothesized that lower concentrations of silver nitrate than had been used in the past would be effective in creating a pleurodesis in rabbits. The following medications in a total volume of 2 mL were instilled intrapleurally in three groups of ten anesthetized rabbits: 0.25% or 0.50% silver nitrate and 35 mg/kg tetracycline. Twenty-eight days after the injection, the animals were sacrificed and the pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The intrapleural injection of 0.50% silver nitrate produced an effective pleurodesis. The mean degree of gross pleurodesis in the rabbits that received 0.50% silver nitrate (3.4 +/- 1.2) did not differ significantly from that of the rabbits that received tetracycline (3.5 +/- 0.7) (scale 0 to 4). The mean degree of microscopic pleural fibrosis in the rabbits that received 0.50% silver nitrate (3.4 +/- 0.7) did not differ significantly from that of the rabbits that received tetracycline (3.9 +/- 0.3). However, 0.25% silver nitrate was ineffective in creating pleural fibrosis, either grossly or microscopically. No rabbits died after the intrapleural injection of the drugs. There were no observed side effects after the injection of silver nitrate. The present study demonstrates that 0.50% silver nitrate instilled into the pleural space is an effective agent for producing pleurodesis in the rabbit; its effect is comparable to tetracycline 35 mg/kg. This agent should be compared with tetracycline derivatives and talc in studies in humans.

A limited renal injury may cause a permanent form of neurogenic hypertension.

Previously, we have shown that an acute injury to the kidney produced by an intrarenal injection of phenol causes an immediate increase in blood pressure and in norepinephrine (NE) secretion from the posterior hypothalamus. The studies suggest that in this model afferent impulses from the kidney to central integrative structures in the brain may be responsible for the increase in blood pressure. To further evaluate whether a renal injury caused by the intrarenal injection of phenol leads to a permanent elevation of blood pressure and whether this is mediated by increased sympathetic nervous system activity, we examined the chronic effects (4 weeks) of an intrarenal injection of 50 microL of 10% phenol on blood pressure and NE secretion from the posterior hypothalamus. Systolic blood pressure increased from 128 +/- 2.1 to 176 +/- 1.5 mm Hg (P < .01) 4 weeks after receiving the intrarenal injection of phenol, but it did not change in rats that received the vehicle (128 +/- 2.4 and 135 +/- 1.7 mm Hg) and in rats that were subjected to renal denervation (127 +/- 3.4 and 124 +/- 1.0 mm Hg). The secretion of NE from the posterior hypothalamic nuclei was greater (P < .01) in rats that received phenol (253 +/- 9.6 pg/mL) than in controls (158 +/- 8.6 pg/mL) and denervated rats (170 +/- 2.1 pg/mL). These studies have shown that a limited injury to one kidney may cause a permanent elevation of blood pressure and this is associated with increased sympathetic nervous system activity.

Histopathological examination of chemo-sympathectomy in cats.

In recent decades, there has been an increase in both the number of sympathectomy techniques, as well as the surgical findings of sympathetic anatomy. Currently the advanced technique of C-arm guided percutaneous thoracic chemo-sympathectomy is widely used for the treatment of palmar hyperhidrosis. However, a better understanding of chemical agents in sympathectomy is required. In this study, chemo-sympathectomy was performed in cats, using alcohol, glycerol and various concentrations of phenol, to determine the chronic neurotoxic effects of these chemical agents on the stellate ganglia. The stellate ganglia of 24 cats were exposed under endotracheal general anesthesia, then injected with about 0.02 ml of absolute alcohol, glycerol and phenol (10%, 25%, 50%, and 75% concentration) solutions, respectively. The stellate ganglia were taken for histological examination three weeks after the chemical injection. The results showed that the degenerative changes in the cytoplasm and nucleus of ganglionic cells and intercellular tissue were moderate and relatively moderate after the injection of alcohol and glycerol, respectively. Meanwhile, the stellate ganglia revealed mild, relatively moderate, serious and extremely serious degeneration after injection of 10%, 25%, 50%, and 75% phenol, respectively. In conclusion, we recommend a high concentration of phenol, in the least volume, as a chemical agent for clinical injection in the upper thoracic sympathetic ganglion.

[Early and late complications of toxic and allergic origin following sclerotherapy in hemorrhoids]. / Früh- und Spätkomplikationen toxischer und allergischer Art nach Sklerotherapie des Hämorrhoidalleidens.

The various disorders occurring after sclerotherapy for hemorrhoids comprise excessive local reactions, necrosis followed by hemorrhage and allergic reactions. Symptoms, prevention and therapy of these adverse effects are detailed.

Occupational paraffin-induced pulmonary fibrosis: a 25-year follow-up.

Exogenous lipid pneumonia can exceptionally be caused by occupational exposure to paraffin. The authors report a case of severe interstitial pulmonary disease induced by occupational exposure to paraffin, leading to delayed fibrosis over a 25-year follow-up, despite cessation of exposure.

Sclerosing effect of OC-108, a novel agent for hemorrhoids, is associated with granulomatous inflammation induced by aluminum.

OC-108 is a novel sclerosing agent for hemorrhoids, containing aluminum potassium sulfate (alum) and tannic acid as its main ingredients. In clinical studies, OC-108 injection therapy for severe internal hemorrhoids proved to be highly effective, not only on bleeding but also for prolapse, and the effects were comparable to hemorrhoidectomy. The aim of this study was to elucidate the mode of action by administrating the agent s.c. to mice and rats. In response to OC-108 injection, inflammation with necrosis developed at an early stage followed by granuloma formation with fibrosis at the injection site. Necrotic debris with aluminum was observed in the granuloma for a long period. Alum, as well as OC-108, induced vascular permeability, leukocyte infiltration, and granuloma formation; however, tannic acid did not. On the other hand, tannic acid inhibited leukocyte infiltration induced by alum but did not inhibit granuloma formation. These results indicate that OC-108 causes sclerosis and retraction of hemorrhoids through fibrosis associated with granulomatous chronic inflammation induced by the main active ingredient alum and that the adjunct ingredient tannic acid reduces excessive acute inflammation induced by alum.

A study of the local toxicity of agents used for variceal injection sclerotherapy.

Injection sclerotherapy is widely used in the treatment of oesophageal varices. However, few studies have compared the local toxicity of sclerosant agents which may be important if serious local complications are to be avoided. In this study the depth of injury caused by submucosal injection of increasing concentrations of sodium tetradecyl sulphate, polidocanol, 5% ethanolamine oleate and 5% varicosid in rabbits stomach, has been compared by histopathological examination. Macroscopic ulceration was seen in 14.6% of injection sites. Increasing concentrations of sodium tetradecyl sulphate and polidocanol produced increasingly extensive microscopic inflammation. Five percent varicosid caused more inflammation than 5% ethanolamine and only 3% polidocanol and 5% varicosid caused full thickness inflammation. Only 5% ethanolamine produced inflammation consistently confined to the mucosa and submucosa. On the basis of this study we feel that 5% ethanolamine is the most suitable agent for injection sclerotherapy.

Extravascular effects of sclerosants in rabbit skin: a clinical and histologic examination.

Sclerotherapy refers to the injection of a material for the purpose of obliterating a blood vessel. During this procedure a small quantity of sclerosing solution may be unintentionally injected into the tissues surrounding the vessel, either by missing the vessel or leakage of sclerosant upon withdrawal of the needle. Occasionally, the sclerosant may be intentionally injected into an extravascular site in the hope of reducing telangiectatic mats (best described as multiple, grouped, extremely fine telangiectatic vessels). The various sclerosants in use appear to vary in their potential to cause necrosis of perivascular tissues as a complication. This study examines the clinical and histologic effects of the intradermal injection of 0.1 ml of 0.25, 0.5, and 1.0% Aethoxysklerol (AES); 0.5% Sotradecol (SOT); and 23.4% hypertonic saline (HS) in rabbit skin. All three agents produced some clinical necrosis with intradermal injection. AES in all three concentrations produced the least clinical necrosis, no histologic necrosis, and resolved faster than SOT or HS.

In vitro and in vivo studies for modified ethyl cyanoacrylate regimens for sclerotherapy.

Cyanoacrylates have known for their ability to polymerize rapidly in the presence of traces of weakly basic moieties such as water. The tissue adhesive, Histoacryl(R) (N-butyl 2-cyanoacrylate), has been reported to control bleeding through endoscopic sclerotherapy. But the commercially available Histoacryl(R) is expensive, and it has the problem like other cyanoacrylates that the glue tends to flow/run away from the point of application, which is inherent to the low viscosity, making precise application difficult. In this study, ethyl cyanoacrylate (ECA), the main constituent of "super glue," was employed instead of Histoacryl(R) due to its lower cost. The aim of the research is to modify the compositions of ECA regimen and evaluate its feasibility for sclerosant application through both in vitro flow circuit model and in vivo animal tests. It was noted that the difference in the relative hardening rate between the in vitro Hepes-Tyrodes buffer flowing model and the in vivo rat model for the ECA and Histoacryl(R) was related to the existence of the blood protein, such as albumin, in the physiological milieu. It was also noticed that the ECA setting rate was greatly increased either in Hepes-Tyrodes buffer or in blood (to a comparable rate as Histoacryl(R) in vivo) by adding a few doses of caffeine, which acts as a polymerization initiator. This would lead to far better injection precision during sclerotherapy. Furthermore, in vivo histological examination for the occluded lumen of the rat's inferior vena cava and a clinical piglet portal vein occlusion experiment have suggested this new sclerosant regimen, caffeine/ECA, is of great promise in endoscopic sclerotherapy.

Hepatotoxic effects of polidocanol in a model of autologously perfused porcine livers.

Polidocanol is an effective sclerosing agent that consists of 95% hydroxypolyethoxydodecane and 5% ethyl alcohol and is known to have a low risk of complications. However, since the compound has been proposed for the local treatment of liver diseases, the potential for topical hepatic side effects should be examined. Therefore, the new model of normothermic-hemoperfused isolated porcine slaughterhouse livers was used to examine polidocanol-hepatotoxicity encompassing the advantages of slaughterhouse organs to reduce animal experiments and autologous blood as an optimal perfusate. Polidocanol was administered via the hepatic artery and portal vein and the effects of the sclerosant on organ function parameters were compared with those in an untreated control group. In contrast to the untreated control organs, significant differences were found in the polidocanol group for parameters such as alanine aminotransferase or organ weight after perfusion. The most striking differences were found for hepatic bile flow, which dropped in the polidocanol group to 0.24+/-0.02 ml/min per 1000 g after administration of the compound compared with 3.80+/-1.08 ml/min per 1000 g in the control group. In summary, the present observations indicate a risk of hepatotoxic effects of polidocanol. Clinicians should be aware of this problem and the use of polidocanol for intrahepatic sclerosing should be restricted to specialized centers.

[Paravasal sclerotherapy: experimental study on the effect of sclerosing agents (author's transl)]. / Experimentelle Untersuchungen zur Wirkung sklerosierender Lösung bei der paravasalen Verödungsbehandlung.

Sclerosing and side effects of three solutions mostly used for paravasal sclerotherapy were studied by subcutaneous injections in lower legs of rats. The results demonstrate that of the three examined sclerosing agents 5 p.c. phenol in almond oil has the lowest toxocity in tissue besides a sufficient production of collagen fibres.

Effect of intravenous and intraperivenous injections of sclerosants (sodium tetradecyl sulfate and hydroxy polyethoxy dodecan) on the rat femoral vein.

The sclerosant effect of injected tetradecyl sulfate of sodium (STS) and hydroxy polyethoxy dodecan (HPD) was studied in the rat femoral vein. Intravenous (i.v.) and intravenous plus perivenous (i.v. + p.v.) injections of both sclerosants and physiologic saline were compared as to vein lumen occlusion, fibrosis, phlogosis, and damage to the artery and surrounding nervous and muscular tissues. The study was carried out in 30 rats treated by STS, in 30 treated by HPD, and 15 animals were injected with saline. The neurovascular bundle and adjacent muscle were removed at 48 h, 7 and 30 days and examined histologically. I.v. injections of STS produced a solid occlusion of the vein in a significant number of cases, after 30 days (P less than 0.01). A statistically significant number of solid occlusions of the femoral vein resulted after i.v. + p.v. injection of STS and HPD, at 48 h, 7 and 30 days (P less than 0.05; P less than 0.01). There was no significant difference between STS and HPD after i.v. + p.v. injection. After i.v. + p.v. we recorded a marked inflammation of muscle with signs of focal necrosis, at 48 h and 7 days. Our study indicated that i.v. + p.v. injection of STS and HPD provided a high degree of efficacy as regards vein occlusion. On the other hand, i.v. + p.v. injection induced a severe inflammation and necrosis of the tissues surrounding the sclerosed vein. Extrapolating our results to the endoscopic sclerotherapy for esophageal variceal bleeding, we conclude that paravariceal injection of sclerosants is a dangerous procedure, even though efficacious to reduce variceal hemorrhage, owing to the high risk of iatrogenic ulcers and esophageal perforation caused by muscular and mucosal necrosis.