Prediction of the skin sensitization potential of didecyldimethylammonium chloride and 3,7-dimethyl-2,6-octadienal and mixtures of these compounds with the excipient ethylene glycol through the human Cell Line Activation Test and the Direct Peptide Reactivity Assay.

In commercial products such as household deodorants or biocides, didecyldimethylammonium chloride (DDAC) often serves as an antimicrobial agent, citral serves as a fragrance agent, and the excipient ethylene glycol (EG) is used to dissolve the active ingredients. The skin sensitization (SS) potentials of each of these substances are still being debated. Moreover, mixtures of DDAC or citral with EG have not been evaluated for SS potency. The in vitro alternative assay called human Cell Line Activation Test (h-CLAT) and Direct Peptide Reactivity Assay (DPRA) served to address these issues. On three independent runs of h-CLAT, DDAC and citral were predicted to be sensitizers while EG was predicted to be a non-sensitizer and also by the DPRA. Mixtures of DDAC or citral with EG at ratios of 7:3 and 1:4 w/v were all positive by the h-CLAT in terms of SS potential but SS potency was mitigated as the proportion of EG increased. Citral and its EG mixtures were all positive but DDAC and its EG mixtures were all negative by the DPRA, indicating that the DPRA method is not suitable for chemicals with pro-hapten characteristics. Since humans can be occupationally or environmentally exposed to mixtures of excipients with active ingredients, the present study may give insights into further investigations of the SS potentials of various chemical mixtures.

Different associations of cryoprotectants for testicular tissue of prepubertal cats submitted to vitrification.

The cryopreservation of testicular tissue is presented as the only alternative for the preservation of genetic material from prepubertal animals. However, this biotechnology is still being tested. The objective of this study was to evaluate the effect of different associations of cryoprotectants and the potential of cell proliferation after vitrification of testicular tissue of prepubertal cats. Five testicular pairs from five prepubertal cats were used, and each pair was divided into four fragments. Of these, one fragment composed of the control group (CG) and the rest were distributed in experimental groups according to the associations of cryoprotectants to be tested (dimethyl sulphoxide (DMSO)/glycerol (GLY); ethylene glycol (EG)/GLY) or DMSO/EG) in a final cryoprotectant concentration of 5.6 m. The fragments were submitted to vitrification, and after one week, fragments were heated and processed for histomorphological evaluation and quantification of nucleolar organizer regions (NORs). DMSO/GLY did not differ from CG and was superior to the other vitrified groups, as to cell separation and degree of shrinkage of the basal membrane. Concerning cell differentiation, visibility of the nucleus and nuclear condensation, all the vitrified groups were inferior to CG; however, DMSO/EG was inferior to DMSO/GLY and EG/GLY, which did not differ among themselves. CG was superior to all groups in quantification of NORs. DMSO/EG was inferior to all others, and there was no difference between DMSO/GLY and EG/GLY. The association DMSO/GLY presented the best preservation of tissue integrity and potential of cell proliferation after vitrification of the testicular tissue of prepubertal cats.

Morphological Evaluation of the Influence of the Peptide Complex from Tissue of Porcine Kidneys on the Experimental Urolithiasis.

We performed morphological analysis of the effect of the peptide complex from porcine kidneys on the course of experimental urolithiasis modeled in rats by treatment with 1% ethylene glycol solution (in drinking water) for 6 weeks. The peptide complex obtained by acetic acid extraction was administered in a dose of 15 mg. Administration of the peptide complex to animals with experimental kidney stone disease leads to 100% destruction of large and medium stones to the "dust" granularity.

L-Arginine attenuates the ethylene glycol induced urolithiasis in ininephrectomized hypertensive rats: role of KIM-1, NGAL, and NOs.

BACKGROUND: Ethylene glycol (EG) exposure caused formation of calcium oxalate crystal that led to renal failure, which is associated with higher prevalence of hypertension. L-Arginine is known to have an antioxidant and nephro-protective potential. OBJECTIVE: To evaluate the effect of L-arginine against EG-induced urolithiasis in uninephrectomized hypertensive rats. MATERIAL AND METHODS: Uninephrectomized male Wistar rats (180-200 g) were used to induce urinary calculi through oral administration of EG (0.75%) in distilled water. Rats were treated with either distilled water (10 mg/kg, p.o.) or telmisartan (10 mg/kg, p.o.) or Cystone (500 mg/kg, p.o.) or L-arginine (250, 500, and 1000 mg/kg, p.o.) for 28 days. Various hemodynamic, biochemical, molecular, and histological parameters were assessed in kidney and heart. RESULTS: Rats treated with L-arginine (500 and 1000 mg/kg) significantly restored altered relative organ weight, urine output, urine density, urinary pH, and water intake. EG-induced alterations in electrocardiographic (QRS interval, HR, and ST height) and hemodynamic (SBP, DBP, MABP, and LVEDP) abnormalities were significantly restored by L-arginine (500 and 1000 mg/kg) treatment. It also significantly restored alteration in serum and urine biochemical parameters induced by EG. The elevated oxido-nitrosative stress was also significantly decreased by L-arginine (500 and 1000 mg/kg) treatment. It also significantly down-regulated EG-induced up-regulated renal KIM-1, NGAL, eNOS, and iNOs mRNA expressions. Histological aberrations induced in the renal and cardiac tissues were also ameliorated by l-arginine treatment. CONCLUSION: L-Arginine exerts its nephro- and cardio-protective potential in EG-induced urolithiasis in uninephrectomized hypertensive rats via modulation of KIM-1, NGAL, eNOS, and iNOs mRNA expression.

Comparison of cryoprotective effects of lycopene and cysteamine in different cryoprotectants on bull semen and fertility results.

The objectives of this study were to compare glycerol and ethylene glycol at different concentrations as cryoprotectants and lycopene or cysteamine (with/without) as antioxidants in Tris extender for bull semen. Twenty-four ejaculates were obtained from three bulls. Each ejaculate was split into four equal aliquots and diluted using both of the Tris extenders with glycerol (5% or 7%) or ethylene glycol (3% or 5%). After that, each extenders were split into three equal aliquots and added using both of the cysteamine 5 mm or lycopene 500 µg/ml, and control (without additives). The addition of 7% glycerol with cysteamine, 5% ethylene glycol with cysteamine and 3% ethylene glycol with cysteamine groups gave the lowest CASA motility than the other groups. However, 7% glycerol and 7% glycerol with lycopene resulted in a better rate of CASA progressive motility compared with that of other groups. Generally, all the lycopene groups signed better protective effects on acrosome and total morphology than the other groups. Glycerol 7% and 3% ethylene glycol with lycopene groups yielded to slight higher percentages of membrane integrity assessed by HOST than that of the other groups, but 7% glycerol with cysteamine and 3% ethylene glycol with cysteamine showed the worst percentages of membrane integrity. Glycerol 7% and 5% glycerol with lycopene gave rise to a higher value of VAP, VSL and VCL compared with that of the other groups. On the contrary, adding to 5% glycerol with cysteamine showed negative effect for VAP, VSL, VCL and ALH values. All cryoprotectant groups with lycopene decreased chromatin damage than the other groups. Ethylene glycol 3% led to lower non-return rates of inseminated cows. However, this result was not considered to be statistically important.

Protective effect of Flos carthami extract against ethylene glycol-induced urolithiasis in rats.

Flos carthami (FC), also known as Carthamus tinctorius, is a traditional Chinese herbal plant that has been prescribed since centuries for treating various symptoms related to blood circulation improvement. This study aimed to investigate the effects of FC on calcium oxalate (CaOx) formation in ethylene glycol (EG)-fed rats. A total of 50 male Sprague-Dawley rats were divided into the following 6 groups: group 1, as the normal control (n = 5); group 2 received gastric gavages of starch and 0.75% EG (placebo, n = 5) as a stone inducer; group 3 (n = 10) received EG and potassium citrate as positive controls; group 4 (n = 10) received 0.75% EG and 300 mg/day FC; group 5 (n = 10) was treated with EG and 600 mg/day FC; group 6 (n = 10) received with EG and 1,200 mg/day FC. For all experimental animals, 24-h urine and blood samples were analyzed at the beginning and end of the experiment. Kidney tissue was histopathologically examined using a polarized light microscope, and crystal deposits were evaluated by a semi-quantitative scoring method; these scores were significantly lower in the FC groups (600 and 1,200 mg/day) than in the placebo group. Thus, FC administration appeared to inhibit the deposition of CaOx crystal EG-fed rats. We, therefore, consider that FC may be effective for preventing stone disease, albeit with certain side effects, such as a bleeding tendency. Further clinical trials are needed for evaluating its benefits and possible side effects.

Phenotypic correction of a mouse model for primary hyperoxaluria with adeno-associated virus gene transfer.

Primary hyperoxaluria type I (PH1) is an inborn error of metabolism caused by deficiency of the hepatic enzyme alanine-glyoxylate aminotransferase (AGXT or AGT) which leads to overproduction of oxalate by the liver and subsequent urolithiasis and renal failure. The current therapy largely depends on liver transplantation, which is associated with significant morbidity and mortality. To explore an alternative treatment, we used somatic gene transfer in a mouse genetic model for PH1 (Agxt1KO). Recombinant adeno-associated virus (AAV) vectors containing the human AGXT complementary DNA (cDNA) were pseudotyped with capsids from either serotype 8 or 5, and delivered to the livers of Agxt1KO mice via the tail vein. Both AAV8-AGXT and AAV5-AGXT vectors were able to reduce oxaluria to normal levels. In addition, treated mice showed blunted increase of oxaluria after challenge with ethylene glycol (EG), a glyoxylate precursor. In mice, AGT enzyme activity in whole liver extracts were restored to normal without hepatic toxicity nor immunogenicity for the 50 day follow-up. In summary, this study demonstrates the correction of primary hyperoxaluria in mice treated with either AAV5 or AAV8 vectors.

[Anti-lithogenic effect of meloxicam in experimental nephrolithiasis].

Experiments performed on 23 male rats, were divided into 2 groups. Animals in the control received group 1% solution of ethylene glycol (EG) as a drink during 6 weeks. In the test group, EG was also introduced for 6 weeks, and meloxicam was administered in a dose of 2.5 mg/kg from the 4th week. Every 7 days, daily urine was analyzed for the concentrations of oxalate, phosphate, and calcium and for the activity of urothelium injury marker enzymes includng lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT), and N-acetyl-beta-D-glucose aminidase (NAG). In addition, sections of the rats kidney were used to detect calcium deposits by histochemical Van Koss method. The treatment of experimental nephrolithiasis by meloxicame led to simplification of pathology, as indicated by a significant reduction in the urine oxalate and calcium concentrations and a pronounced decrease in the activity of all marker enzymes (LDH, GGT, NAG).This was confirmed by morphological studies, which detected very significant reduction in both number and size of calcium deposits.

A joint modeling approach to data with informative cluster size: robustness to the cluster size model.

In many biomedical and epidemiological studies, data are often clustered due to longitudinal follow up or repeated sampling. While in some clustered data the cluster size is pre-determined, in others it may be correlated with the outcome of subunits, resulting in informative cluster size. When the cluster size is informative, standard statistical procedures that ignore cluster size may produce biased estimates. One attractive framework for modeling data with informative cluster size is the joint modeling approach in which a common set of random effects are shared by both the outcome and cluster size models. In addition to making distributional assumptions on the shared random effects, the joint modeling approach needs to specify the cluster size model. Questions arise as to whether the joint modeling approach is robust to misspecification of the cluster size model. In this paper, we studied both asymptotic and finite-sample characteristics of the maximum likelihood estimators in joint models when the cluster size model is misspecified. We found that using an incorrect distribution for the cluster size may induce small to moderate biases, while using a misspecified functional form for the shared random parameter in the cluster size model results in nearly unbiased estimation of outcome model parameters. We also found that there is little efficiency loss under this model misspecification. A developmental toxicity study was used to motivate the research and to demonstrate the findings.

Methanolic extract of Cucumis melo attenuates ethylene glycol-induced nephrolithiasis in Wistar rats.

Evaluation of the effects of methanolic extract of Cucumis melo in ethylene glycol-induced nephrolithiasis on Wistar rats. 0.75% solution of ethylene glycol (EG) in payable water was given to produce nephrolithiasis on Wistar rats. The action of oral intake of methanolic extract of Cucumis melo seed in nephrolithiasis is studied and is matched with the action of oral intake of Cystone (standard) on Wistar rats. EG resulted in hyperoxaluria and deposition of calcium oxalate as well as raised urinary excretion of oxalate and calcium. Supplementation with methanolic extract of Cucumis melo seed decreased the increased renal oxalate, indicating a regulatory effect on oxalate formation endogenously. The outcomes stipulate that the seed of Cucumis melo is endowed with antinephrolithiatic action.

A different perspective on the filtration barrier after kidney stone formation: An immunohistochemical and biochemical study.

The aim of this study is to investigate whether the filtration barrier is affected by experimental kidney stone formation. Thirty-two rats divided into 4 equally groups (n = 8) at random. Group I control; Group II 1% ethylene glycol; Group III 1% Ethylene glycol + 0.25% Ammonium chloride; Group IV 1% Ethylene glycol + 0.5% Ammonium chloride group. Tissues applied hematoxylin-eosin, periodic-acid-Schiff, Pizzolato's staining. Immunohistochemically stained with integrin α3ß1, type IV collagen, laminin, nephrin, CD2-associated protein (CD2AP) and podocin to show the filtration barrier structure. The TUNEL method was used for apoptosis. The amount of calcium, magnesium, creatinine and uric acid in urine and blood samples, also urine microprotein determined. Stones were formed in all experimental groups. Urine calcium, creatinine, uric acid levels decreased, magnesium levels were not changed. No statistically significant change was observed in blood serum results and TUNEL analysis. Immunohistochemical results showed an increase in nephrin, podocin, CD2AP, laminin and a decrease in integrin α3ß1 and type IV collagen. Consequently, there is an increase in the expression densities of the proteins incorporated in the structure to prevent loss of functionality in the cellular part supporting the structure against a weakening of the basement membrane structure in the glomerular structure in which urine is filtered.

Antiurolithic effects of medicinal plants: results of in vivo studies in rat models of calcium oxalate nephrolithiasis-a systematic review.

Urolithiasis is one of the oldest diseases affecting humans, while plants are one of our oldest companions providing food, shelter, and medicine. In spite of substantial progress in understanding the pathophysiological mechanisms, treatment options are still limited, often expensive for common people in most parts of the world. As a result, there is a great interest in herbal remedies for the treatment of urinary stone disease as an alternative or adjunct therapy. Numerous in vivo and in vitro studies have been carried out to understand the efficacy of herbs in reducing stone formation. We adopted PRISMA guidelines and systematically reviewed PubMed/Medline for the literature, reporting results of various herbal products on in vivo models of nephrolithiasis/urolithiasis. The Medical Subject Heading Terms (Mesh term) "Urolithiasis" was used with Boolean operator "AND" and other related Mesh Unique terms to search all the available records (July 2019). A total of 163 original articles on in vivo experiments were retrieved from PubMed indexed with the (MeshTerm) "Urolithiasis" AND "Complementary Therapies/Alternative Medicine, "Urolithiasis" AND "Plant Extracts" and "Urolithiasis" AND "Traditional Medicine". Most of the studies used ethylene glycol (EG) to induce hyperoxaluria and nephrolithiasis in rats. A variety of extraction methods including aqueous, alcoholic, hydro-alcoholic of various plant parts ranging from root bark to fruits and seeds, or a combination thereof, were utilized. All the investigations did not study all aspects of nephrolithiasis making it difficult to compare the efficacy of various treatments. Changes in the lithogenic factors and a reduction in calcium oxalate (CaOx) crystal deposition in the kidneys were, however, considered favorable outcomes of the various treatments. Less than 10% of the studies examined antioxidant and diuretic activities of the herbal treatments and concluded that their antiurolithic activities were a result of antioxidant, anti-inflammatory, and/or diuretic effects of the treatments.

Experimental induction of calcium oxalate nephrolithiasis in mice.

PURPOSE: The availability of various transgenic and knockout mice provides an excellent opportunity to better understand the pathophysiology of calcium oxalate stone disease. However, attempts to produce calcium oxalate nephrolithiasis in mice have not been successful. We hypothesized that calcium oxalate nephrolithiasis in mice requires increasing urine calcium and oxalate excretion, and experimentally induced hyperoxaluria alone is not sufficient. To provide evidence we induced hyperoxaluria by administering hyperoxaluria inducing agents in normocalciuric and hypercalciuric mice, and investigating various aspects of nephrolithiasis. MATERIALS AND METHODS: We administered ethylene glycol, glyoxylate or hydroxyl proline via diet in male and female normocalciuric B6 mice, and in hypercalciuric sodium phosphate co-transporter type 2 a -/- mice for 4 weeks. We collected 24-hour urine samples on days 0, 3, 7, 14, 21 and 28, and analyzed them for pH, creatinine, lactate dehydrogenase calcium and oxalate. Kidneys were examined using light microscopy. Urine was examined for crystals using light and scanning electron microscopy. RESULTS: Hypercalciuric mice on hydroxyl proline did not tolerate treatment and were sacrificed before 28 days. All mice on ethylene glycol, glyoxylate or hydroxyl proline became hyperoxaluric and showed calcium oxalate crystalluria. No female, normocalciuric or hypercalciuric mice showed renal calcium oxalate crystal deposits. Calcium oxalate nephrolithiasis developed in all mice on glyoxylate and in some on ethylene glycol. In all mice the kidneys showed epithelial injury. Male mice particularly on glyoxylate had more renal injury and inflammatory cell migration into the interstitium around the crystal deposits. CONCLUSIONS: Results confirm that hyperoxaluria induction alone is not sufficient to create calcium oxalate nephrolithiasis in mice. Hypercalciuria is also required. Kidneys in male mice are more prone to injury than those in female mice and are susceptible to calcium oxalate crystal deposition. Perhaps epithelial injury promotes crystal retention. Thus, calcium oxalate nephrolithiasis in mice is gender dependent, and requires hypercalciuria and hyperoxaluria.

Ethylene glycol induced hyperoxaluria increases plasma and renal tissue asymmetrical dimethylarginine in rats: a new pathogenetic link in hyperoxaluria induced disorders.

PURPOSE: The pathogenesis of kidney stones remains elusive. There is some evidence that hyperoxaluria may effect vascular endothelium and many studies link renal stones to atherosclerosis. Also, renal vascular endothelial cells regulate proximal tubular epithelial cell function. We determined the effect of hyperoxaluria on plasma and tissue levels of asymmetrical dimethylarginine. The secondary aim was to determine the effect of verapamil on asymmetrical dimethylarginine. MATERIALS AND METHODS: A total of 42 Sprague-Dawley rats were included in the study. In groups 1A, 1B and 1C hyperoxaluria was induced with ethylene glycol for 2 weeks. Groups 2A, 2B and 2C received ethylene glycol for 14 days and verapamil for 28 days. Control group 3 received no specific medication but distilled water. Blood samples were obtained at 24 hours and at study end, and kidney samples were obtained at 24 hours, and 7 and 28 days for histopathological evaluation. RESULTS: Plasma asymmetrical dimethylarginine increased early in the hyperoxaluric group (p = 0.0002). The effect was retained at the end of the study period (p = 0.01). There was no increase in asymmetrical dimethylarginine in the verapamil group on short-term and long-term followup. Hyperoxaluria induced a significantly dense staining pattern in renal tissue asymmetrical dimethylarginine vs controls (p = 0.01). Asymmetrical dimethylarginine staining did not differ in the control and verapamil groups. CONCLUSIONS: Increased systemic and local tissue asymmetrical dimethylarginine may help explain the pathogenetic mechanisms of hyperoxaluria induced disorders such as nephrolithiasis and atherosclerosis.

Pyrrolidine dithiocarbamate treatment prevents ethylene glycol-induced urolithiasis through inhibition of NF-kappaB and p38-MAPK signaling pathways in rat kidney.

The aim of this study was to evaluate the role of the inducible nitric oxide synthase (iNOS), selective nuclear factor-kappaB (NF-kappaB) and p38-mitogene-activated protein kinase (p38-MAPK) on oxalate-induced crystal deposition in renal tubules. The rats were divided into three groups; group 1; control group, group 2; ethylene glycol (EG) group, group 3; EG + pyrrolidine dithiocarbamate (PDTC) group. Rats were sacrified on 7, 15 and 45th days. The iNOS expression, p65/NF-kappaB and p38/MAPK activity, and oxidative stress markers were evaluated in the kidney. Crystal depositions were evident on day 7, mild and severe crystallization were observed on day 15 and 45 in EG group, respectively. There was limited or no crystal formation in the EG + PDTC group. While EG stimulates iNOS, p65/NF-kappaB and p38/MAPK activity in renal tubules, PDTC inhibited it. PDTC prevents crystal depositions in renal tubules by reducing oxidative stress, iNOS, NF-kappaB, and p38-MAPK expression.

The preventive and therapeutic effects of α-lipoic acid on ethylene glycol-induced calcium oxalate deposition in rats.

OBJECTIVE: To investigate the effect of α-lipoic acid (α-LA) in the prevention and treatment of ethylene glycol-induced calcium oxalate deposition in a rat model and preliminary exploration of the mechanism. METHODS: Sixty male Wistar rats were divided randomly and equally into six groups including two α-LA prevention groups, two α-LA therapeutic groups, one controlled group and one intervention group. Besides controlled group, other group received 1% glycol solution and 2 ml 2% ammonium chloride for 4 weeks as a stone inducer. The prevention groups received 0.1 and 0.2 mg/kg body weight/day/rat α-LA as food supplement during inducing stone and therapeutic groups received 0.1 and 0.2 mg/kg body weight/day/rat α-LA for 4 weeks after 4 weeks stone inducing. RESULTS: The volume of urine, the pH and magnesium levels in the preventive and therapeutic groups were higher in a dose-independent manner (p < 0.05), and urinary calcium was lower (p < 0.05). Antioxidant stress enzyme activity (glutathione, superoxide dismutase, catalase) in serum and kidney homogenates in the preventive and therapeutic groups underwent significant regeneration (p < 0.05) and malondialdehyde levels and the production of free radical moieties decreased. Pathological observation demonstrated that there was deformation due to renal tubular expansion in the control group, greater visible inflammatory cell infiltration into the interstitial spaces and partial destruction of the glomerular structures. α-lipoic acid improved the lesions to varying degrees. The extent of crystal deposition was lower in the preventive and therapeutic groups compared with the control group (p < 0.05). CONCLUSION: The present study indicated that α-LA provides both preventive and therapeutic effects against the deposition of calcium oxalate crystals in rats.

Nephroprotective Effect of Pleurotus ostreatus and Agaricus bisporus Extracts and Carvedilol on Ethylene Glycol-Induced Urolithiasis: Roles of NF-κB, p53, Bcl-2, Bax and Bak.

This study was designed to assess the nephroprotective effects of Pleurotus ostreatus and Agaricus bisporus aqueous extracts and carvedilol on hyperoxaluria-induced urolithiasis and to scrutinize the possible roles of NF-κB, p53, Bcl-2, Bax and Bak. Phytochemical screening and GC-MS analysis of mushrooms' aqueous extracts were also performed and revealed the presence of multiple antioxidant and anti-inflammatory components. Hyperoxaluria was induced in Wistar rats through the addition of 0.75% (v/v) ethylene glycol in drinking water for nine weeks. The ethylene glycol-administered rats were orally treated with Pleurotus ostreatus and Agaricus bisporus aqueous extracts (100 mg/kg) and carvedilol (30 mg/kg) daily during the last seven weeks. The study showed that Pleurotus ostreatus, Agaricus bisporus and carvedilol all successfully inhibited ethylene glycol-induced histological perturbations and the elevation of serum creatinine, serum urea, serum and urinary uric acid, serum, urinary and kidney oxalate, urine specific gravity, kidney calcium, kidney NF-κB, NF-κB p65, NF-κB p50, p53, Bax and Bak expressions as well as serum TNF-α and IL-1ß levels. Moreover, the treatment decreased the reduction in urinary creatinine, urinary urea, ratios of urinary creatinine to serum creatinine and urinary urea to serum urea, Fex Urea and Bcl-2 expression in kidney. In conclusion, although Pleurotus ostreatus and Agaricus bisporus extracts and carvedilol all significantly inhibited the progression of nephrolithiasis and showed nephroprotective effects against ethylene glycol-induced kidney dysfunction, Pleurotus ostreatus and Agaricus bisporus seemed to be more effective than carvedilol. Moreover, the nephroprotective effects may be mediated via affecting NF-κB activation, extrinsic apoptosis and intrinsic apoptosis pathways.

Skin Permeation of Urea Under Finite Dose Condition.

In a previous study investigating the relationships between solute physicochemical properties and solvent effects on skin permeation of solutes under finite dose conditions, urea was found to have the highest percent dose absorbed among the model solutes studied. The objective of this study is to probe the mechanism of the observed high skin permeation of urea at finite dose, in contrast to its permeability coefficient obtained under infinite dose condition. Skin permeation experiments were performed with Franz diffusion cells and human epidermal membrane. Dose-dependence and penetration enhancing effects of urea permeation were investigated. Tape stripping was performed. A small hydrophilic solute ethylene glycol with molecular weight similar to urea was studied for comparison. The results suggest that urea did not have penetration enhancing effect to enhance solute permeation across skin under the finite dose conditions. Tape stripping data are consistent with skin permeation mechanism of solute deposition and diffusion. The skin permeation behavior of urea could be attributed to its small molecular size. This suggests that, under the finite dose conditions examined in this study, solutes with molecular sizes similar to or less than urea and ethylene glycol could lead to high percent of skin absorption despite their hydrophilicities.

Correction of hyperoxaluria by liver repopulation with hepatocytes in a mouse model of primary hyperoxaluria type-1.

BACKGROUND: Primary hyperoxaluria type-1 (PH1) is an autosomal recessive disease characterized by excessive oxalate production by hepatocytes caused by the deficiency of peroxisomal alanine-glyoxylate aminotransferase (AGT) activity. Persistent hyperoxaluria causes nephrocalcinosis and urolithiasis, leading to renal failure, followed by tissue oxalosis with life-threatening complications. Combined liver-kidney transplantation is the only definitive treatment of PH1. Hepatocyte transplantation, which is much less invasive, could have offered an attractive alternative. However, because the AGT-deficient hepatocytes overproduce oxalate, a large fraction of the mutant host hepatocytes must be replaced by AGT-competent cells, which is beyond the capacity of current hepatocyte transplantation procedures. Here, we have evaluated a preparative irradiation-based method of liver repopulation in an Agxt-deleted mouse model of PH1 (Agxt-/-). MATERIALS AND METHODS: Hepatocytes (10(6) viable cells) isolated from congeneic mice ([ROSA]26 C57BL/6J) expressing Escherichia coli beta-galactosidase were transplanted into Agxt-/- mice by intrasplenic injection. The preparative regimen consisted of X-irradiation of the host liver and mitotic stimulation of the hepatocytes by adenovector-based expression of hepatocyte growth factor. RESULTS: The procedure resulted in progressive replacement of the mutant host hepatocytes with the AGT-competent hepatocytes, leading to correction of urinary oxalate excretion. Oral ethylene glycol challenge (0.7% for 1 week) resulted in nephrocalcinosis and microlithiasis in untreated Agxt-/- mice, but not in the mice after hepatic repopulation. CONCLUSION: The results indicate that hepatocyte transplantation after appropriate preparative regimens may permit sufficient repopulation of the liver to ameliorate hyperoxaluria, and therefore should be evaluated further as a potential treatment of PH1.

The effect of internal and external cryoprotectants on zebrafish (Danio rerio) embryos.

The study investigated the effects of internal (DMSO, 1,2-propanediol, glycerol, ethylene glycol, methanol, N,N-dimethylacetamide) and external cryoprotectants (glucose, sucrose) on the viability and on morphometric parameters of zebrafish embryos. From the tested internal cryoprotectants, DMSO had the lowest toxicity, followed by 1,2-propanediol and glycerol. The external cryoprotectants were less toxic then the internal ones. Early ontogenetic stages were more sensible to cryoprotectant exposure than advanced stages. Two-step incubation procedures in increasing concentrations of internal and external cryoprotectants were superior to multiple-step exposure procedures. All tested vitrification solutions exceeded the tolerance limit of embryos. The tolerance of zebrafish embryos to cryoprotectants was highly variable in a concentration range causing approximately 50% embryo mortality. The width of the perivitelline space showed significant morphometrical changes due to cryoprotectant exposure. In the germinative tissue non-significant changes occurred. The yolk did not change morphometrically after exposure to internal cryoprotectants and showed no sign of dehydration after exposure to external cryoprotectants. Based on these results the study comes to the following conclusions: as yolk dehydration was impossible and as vitrification solutions were over the tolerance limit it seems unlikely that successful vitrification of zebrafish embryos can be achieved. Under these considerations slow freezing methods would be a better option as lower cryoprotectant concentrations can be used and embryos can be dehydrated during freezing.