Pulsed electromagnetic fields accelerate wound healing in the skin of diabetic rats

Delayed wound healing is a common complication in diabetes mellitus. From this point of view, the main purpose of the present study is to investigate the effect of extremely low frequency pulsed electromagnetic fields (ELF PEMFs) on skin wound healing in diabetic rats. In this study, diabetes was induced in male Wistar rats via a single subcutaneous injection of 65 mg/kg streptozocin (freshly dissolved in sterile saline, 0.9%). One month after the induction of diabetes, a full‐thickness dermal incision (35 mm length) was made on the right side of the paravertebral region. The wound was exposed to ELF PEMF (20 Hz, 4 ms, 8 mT) for 1 h per day. Wound healing was evaluated by measuring surface area, percentage of healing, duration of healing, and wound tensile strength. Obtained results showed that the duration of wound healing in diabetic rats in comparison with the control group was significantly increased. In contrast, the rate of healing in diabetic rats receiving PEMF was significantly greater than in the diabetic control group. The wound tensile strength also was significantly greater than the control animals. In addition, the duration of wound healing in the control group receiving PEMF was less than the sham group. Based on the above‐mentioned results we concluded that this study provides some evidence to support the use of ELF PEMFs to accelerate diabetic wound healing. Further research is needed to determine the PEMF mechanisms in acceleration of wound healing in diabetic rats. Bioelectromagnetics 31:318–323, 2010. © 2010 Wiley‐Liss, Inc.     

Effect of DDT on hepatic mixed-function oxidase activity in normal and vitamin A-deficient rats

Feeding of vitamin A-deficient diet to male weanling rats for 10 weeks resulted in significant decrease in the body weight and marked reduction in the hepatic vitamin A content. The levels of hepatic phase I microsomal enzymes cytochrome P-450, cytochrome b5, aminopyrine N-demethylase and arylhydrocarbon hydroxylase were found to be substantially reduced by vitamin A-deficiency. Also, the activity of phase II microsomal UDP - glucuronyl transferase enzyme was significantly decreased in deficient animals. Following repeated oral administration of DDT (15 mg/kg/body wt/day) for 21 days, the phase I microsomal enzymes were induced to a greater extent in controls as compared to deficient animals. UDP - glucuronyltransferase remained insensitive to DDT induction. The results imply that the capacity for induction of the hepatic mixed-function oxidase enzyme system is impaired in deficient animals concurrently exposed to DDT.     

Inhibition of two rat hepatic microsomal drug-metabolizing enzymes by a carcinogenic N-nitrosated pesticide: N-nitrosocarbaryl

N-Nitrosocarbaryl (N-methyl-1-naphthyl N-nitrosocarbamate) was intraperitoneally administered to male and female rats on four consecutive days at the following doses: 6.25 mg, 12.5 mg, 25 mg and 50 mg/kg body weight/day in olive oil solution; the controls received just the oil. In a second experiment, a daily intraperitoneal dose of 25 mg/kg of N-nitrosocarbaryl was given for 1, 2, 3 or 4 days; the animals were killed 24 h after the last treatment. The two following microsomal enzymatic activities were assayed: aniline aromatic hydroxylase and p-nitroanisole O-demethylase; the levels of cytochrome P-450, proteins and RNA were measured in the hepatic microsomal fraction. N-Nitrosocarbaryl is an inhibitor of the two investigated microsomal monooxygenases at doses of 25 and 50 mg/kg when administered on 4 consecutive days. During the daily administration, enzyme inhibition is seen in females after one day of treatment whereas cytochrome P-450 only becomes lowered after 4 days of administration. In males, no modification of this parameter is observed whereas the activities of microsomal monooxygenases are inhibited. These results suggest that N-nitrosocarbaryl could act on the active sites of the enzymes which metabolize aniline and p-nitroanisole.     

Pyramid environment reduces the wound healing suppressant properties of dexamethasone in albino rats

With a view to investigate the contribution and role of environment within a wooden pyramid model on the wound healing suppressant effect of dexamethasone in rats, wound breaking strength, dry weight, hydroxyproline content and histology of granulation tissue of the dead space wound were studied in rats. The results indicate that the environment within the wooden pyramid not only promotes significant wound healing but also reduces the wound healing suppressant effect of dexamethasone. Histological studies also confirmed the results.     

Effect of cyclosporin on tumor xenotransplantation under the renal capsule in mice

Stimulating effect of cyclosporine on growth and invasiveness of tumor xenographts was studied on a model of rat solid sarcoma M-1 transplanted under the kidney capsule in mice. Cyclosporine was administered subcutaneously in a dose of 25 or 75 mg/kg on days 1-7. The stimulating effect of cyclosporine was directly associated with the immunodepressant dose and accompanied by a decrease in the thymus weight. With using cyclosporine the model of xenographts under the kidney capsule can be of value in screening cytostatics and immunomodulators.     

Chronomodulatory effect of cyclosporine upon survival of DBA mice with L1210 leukemia

A circadian stage-dependent anti-tumor effect of cyclosporine was tested on 268 female DBA mice, 9-10 weeks of age. The mice were kept in 6 different environmental chambers on regimens of 12h of light alternating with 12h of darkness, staggered by 4h: they were inoculated intraperitoneally with 2 X 10(5) L1210 cells at one of 6 different circadian stages. At the same circadian stage, starting 48h after inoculation, for 4 days, each mouse received the vehicle, a fixed dose of cyclosporine (15 mg/kg b.w.), a varying dose of cyclosporine 5, 10, 20 and 25 mg/kg b.w.) or no treatment. Cyclosporine prolonged survival time in a circadian stage dependent fashion (p less than 0.01), as shown by an analysis of variance and by cosinor analysis (mesor = 8.45h; amplitude = 5.45h; acrophase = 12 HALO). Cyclosporine thus acts, in a feed-sideward, as a chronomodulator of the interaction between the tumor and its host.     

Effect of sodium diphenylhydantoin on skin wound healing in rats

This study evaluated the effect of phenytoin (sodium diphenylhydantoin) on skin wound healing in a rat model. The study was divided into two parts. In part I, 20 mul of phenytoin (10 mg/ml) was subcutaneously injected into the 3-cm dorsal full-thickness incisional wounds of 14 rats on postoperative days 0, 3, and 6. Twelve rats that received saline injections were used as the controls. The skin samples were harvested and tested for tensile strength and histology. An additional 12 rats with the same incisional wounds were tested for chemokine gene expressions. In part II, 20 mul of phenytoin (10 mg/ml) was applied topically once a day on a 4 x 4 cm area of the open dorsal wounds of 10 rats. Saline was applied to the wounds of the 10 control group rats. The wounds were measured weekly. The results showed that the average tensile strength of the phenytoin-treated wound was 0.49 +/- 0.08 MPa compared with the control group at 0.02 +/- 0.01 MPa (p < 0.05). The density ratio of chemokine monocyte chemotactic protein (MCP-1) to beta-actin in the phenytoin-treated group was also significantly higher than in the control group (p < 0.05). Histologic analysis of the phenytoin group showed a large amount of fibroblast proliferation, collagen synthesis, and neovascularization. Phenytoin-treated wounds were also smaller at 1 to 6 weeks postoperatively than the control group wounds. The authors conclude that the administration of phenytoin can promote wound healing and significantly increase MCP-1 expression. Phenytoin-treated wounds showed significant increase in collagen deposition and neovascularization, which resulted in an increased wound tensile strength and accelerated healing of both open and closed wounds.     

Wound healing studies of Aristolochia bracteolata Lam. with supportive action of antioxidant enzymes

Aristolochia bracteolata is a perennial herb, the leaves of which are used by the native tribals and villagers of the Chittoor District of Andhra Pradesh in India for the rapid healing of cuts and wounds. The ethanol extract of the shade-dried leaves of Aristolochia bracteolata Lam. was studied for its effect on wound healing in rats, using incision, excision and dead-space wound models, at two different dose levels of 400 and 800 mg/kg/body wt./day. The plant showed a definite, positive effect on wound healing, with a significant increase of the level of two powerful antioxidant enzymes, super oxide dismutase and catalase, in the granuloma tissue.     

Effect of Dehydrozingerone, a half analog of curcumin on dexamethasone-delayed wound healing in albino rats

Oxidative stress is triggered by the wound which results in the production of reactive oxygen species (ROS), thereby delaying normal wound repair. Therefore, it is important to reduce the level of ROS to improve healing. A known antioxidant, dehydrozingerone (DHZ) was synthesized and selected for the study. The authors aimed to investigate the wound healing action of topical (100 mg/wound) and systemic (100 mg/kg, p. o.). DHZ on different wound models in normal and dexamethasone (DEX)-suppressed healing. Topical DHZ showed a significant (P < 0.05) rise in tensile strength when compared to control in normal healing. Significant (P < 0.05) wound closure was observed from 3 to 9 days in DHZ oral and gel treated groups. There was a significant (P < 0.05) rise in hydroxyproline content with the DHZ treated groups when compared to control. Systemic DHZ exhibited a significant (P < 0.05) increase in lysyl oxidase (LO) levels of 3.73 ± 0.15 nmol of H(2)O(2) when compared to control. In DEX-suppressed healing, showed good pro-healing activity with respect to the parameters mentioned above. DHZ treatment exhibited a parabolic dose response of ROS inhibition with a plateau effect at 75 μM. There was a steady and constant increase in the % NO inhibition with increasing doses of DHZ. Oral DHZ is effective in accelerating the healing process in both normal and dexamethasone-suppressed wounds. Our study suggests that DHZ (half analog of curcumin) supplementation reduces the steroid-induced delay in wound healing.     

An investigation on skin wound healing in mice with a taurine-chitosan gel formulation

Summary. The process of wound healing begins immediately following surface lesions or just after exposure to radiation, chemical agents or extreme temperatures. Taurine (2-aminoethane sulfonic acid), an amino acid containing sulfur, is found in almost all tissues in mammals, playing various important physio-logical roles in each organ. Taurine exhibits an antioxidant effect and is also known to have effects on cell proliferation, inflammation and collagenogenesis. Many antioxidants have been used to eliminate the negative effects of oxygen free radicals on wound healing. The objective of the present study was to examine the wound healing effect in mice of taurine-chitosan gel, which releases taurine slowly over a long time period. Fifty mM of taurine in 1.5% chitosan polymer (TAU-GEL) and 1.5% chitosan polymer (CHI-GEL) were applied to full thickness skin wounds of mice once a day for seven days. After seven days of treatment, lipid peroxide formation-malondialdehyde (MDA) and hydroxyproline (HPX) levels and the tensile strength of wound tissues were measured. All results were compared with those of the untreated control group (CONT). The structural alterations in the skin layers were also histologically investigated. It was found that locally administered TAU-GEL form significantly increased wound tensile strength by decreasing the MDA and increasing HPX levels. These results were supported by histological findings. All observations suggest that taurine gel may be effective in wound healing. Received January 15, 2001 Accepted June 4, 2001     

Destruction of hepatic mixed-function oxygenase parameters by CCl4 in rats following acute treatment with chlordecone, Mirex, and phenobarbital

Previous work has established the marked potentiation of CCl4 hepatoxicity by prior exposure to chlordecone (CD). This study was conducted to determine if prior exposure to CD results in enhancement of CCl4-induced destruction of the hepatic microsomal mixed-function oxygenase (MFO) system. Male Sprague-Dawley rats received a single oral dose of CD (10 mg/kg) or corn oil vehicle alone (1 ml/kg) 24 hr prior to a single ip injection of CCl4 (0-100 microliter/kg). Mirex (M; 10 mg/kg) and phenobarbital (PB; 80 mg/kg/day for two days) were used as negative and positive controls respectively for the potentiation of CCl4 hepatotoxicity. Hepatotoxicity was evaluated 24 hrs after CCl4 administration by elevations of three serum enzymes (GPT, GOT, and ICD). The key hepatic microsomal MFO parameters measured were microsomal protein, cytochrome P-450 content, glucose-6-phosphatase (G-6-Pase), and aminopyrine demethylase (APD). As previously demonstrated using a subchronic dietary pretreatment protocol, CD potentiated CCl4 hepatotoxicity over a range of CCl4 doses to a greater extent than PB or M, as judged by elevations in serum enzymes. PB caused the greatest increase in total P-450 content and the greatest increase in CCl4-mediated destruction of microsomal protein and APD activity. M caused the least destruction of total hepatic cytochrome P-450, despite the same level of cytochrome P-450 as in the PB group. CD treatment caused the greatest decrease in G-6-Pase activity in comparison to PB or M pretreatments and a similar degree of P-450 destruction as observed with the PB group. These findings suggest that in general, CCl4-induced destruction of hepatic MFO parameters measured in this study is disproportional to the known degree of potentiated hepatotoxicity by the pretreatments and does not accurately reflect the potentiation of CCl4 hepatotoxicity by CD.     

The effect of EGF application in gel form on histamine content of experimentally induced wound in mice

Summary. The factors participating to the wound healing are complex and still obscure. Among these factors, epidermal growth factor (EGF) and histamine by increasing reepithelization and reparation tissue strength via enhancing collagen deposition to the wound site have a beneficial effect. This study was performed to investigate the effect of EGF dosage forms on the histamine content of the experimentally induced wound and some wound healing criters in the mice.Histological investigation of reepithelization, wound tensile strength for healing and collagen maturation, and histamine levels were assessed in the present study. Thirty two mice were divided into control, and EGF treated groups. Controls included three subgroups; untreated (n=5), 0.9% NaCl applied (n=5), and gel applied (n=5). Experimental groups were treated with two forms of EGF; EGF, solution form in 0.9% NaCl (n=5) and the gel form in 0.2% w/w in carbopol 940 (n=7). The discrepancy between these forms were evaluated. This evaluation was done by the application of two forms of EGF for 15 days on experimentally induced wound healing.Gel form of EGF by sustained release from bioadhesive polymer is found to be more effective than the soluble form, on the healing of the wound, by acceleration of reepithelization and increment of wound tensile strength. The tensile strength of the wound indicates the rate of repair and collagen maturation. It has been observed that when physiological saline and carbopol 940 exposed to incision without EGF causes a significant increase in tissue histamine content.According to the results of the present investigation; the histamine content is found to be decreased by EGF gel dosage form treatment, therefore preventing abnormal collagen formation has a beneficial effect on wound healing.     

Enhanced wound contraction and epithelization period in steroid treated rats: role of pyramid environment

Contribution and role of a pyramid/square box on the wound healing suppressant effect of dexamethasone was studied in rats of either sex using excision wound model to record the wound contraction rate and epithelization period. The results showed enhanced wound contraction rate and decreased epithelization period in the pyramid-exposed rats as compared to controls. Thus, it appears that pyramid environment facilitates the process of wound healing. Also, the wound healing suppressant effects of dexamethasone were significantly reduced.     

Attenuation of low dose phenobarbital induction of hepatic microsomal aminopyrine N-demethylase activity in rats by cimetidine

Cimetidine, a substituted imidazole, is an inhibitor of hepatic cytochrome P-450-mediated drug metabolism in rats and humans. We investigated the effect of cimetidine on phenobarbital induction of hepatic microsomal aminopyrine N-demethylase activity in the rat. Phenobarbital induction of aminopyrine N-demethylase was log-linear in the range of 1-6 mg/kg/day and the ED50 was approximately 3 mg/kg/day. Cimetidine 75 mg/kg (four times a day) attenuated the induction of aminopyrine N-demethylase activity by 58% in low dose (3 mg/kg/day) but not in high dose (40 mg/kg/day) phenobarbital treated rats. This result could not be explained by residual inhibition of enzyme activity by cimetidine and suggests that cimetidine affects the induction of hepatic cytochrome P-450 by low dose phenobarbital.     

Wound healing property of ethanolic extract of leaves of Hyptis suaveolens with supportive role of antioxidant enzymes

Ethanolic extract of leaves of Hyptis suaveolens was evaluated for its wound healing activity in ether-anaesthetized Wistar rats at two different doses (400 and 800 mg/kg) using incision, excision, and dead space wound model. Significant increase in skin breaking strength, granuloma breaking strength, wound contraction, hydroxyproline content and dry granuloma weight and decrease in epithelization period was observed. A supportive study made on granuloma tissue to estimate the levels of catalase and superoxide dismutase recorded a significant increase in the level of these antioxidant enzymes. Granuloma tissue was subjected to histopathological examination to determine the pattern of lay-down for collagen using Van Gieson and Masson Trichrome stains. Enhanced wound healing activity may be due to free radical scavenging action of the plant and enhanced level of antioxidant enzymes in granuloma tissue. Better collagenation may be because of improved antioxidant studies.     

Regulation of hepatic drug metabolism by elaidic and linoleic acids in rats.

Elaidic and linoleic acids were administered at doses of 40 and 200 mg/kg i.p. every second day for 4 weeks to rats fed a fat-free diet. The fatty acids had only a slight effect on the weight gain of the animals. The amount of microsomal protein was slightly decreased with the higher dose of linoleic acid. The higher dose level of both fatty acids decreased the microsomal phospholipid content. The relative amounts of microsomal phospholipid fatty acids were also altered due to fatty acid administration. The activity of microsomal NADPH cytochrome c reductase and microsomal cytochrome P-450 contents were decreased by the higher dose of linoleic acid. The hepatic aryl hydrocarbon hydroxylase and p-nitroanisole O-demethylase activities decreased in fatty acid-treated rats. The UDP-glucuronosyltransferase activity was also lowered after the fatty acid administration. The results suggest that fatty acid-induced changes in the activities of drug-metabolizing enzymes may be due to the microenvironmental changes of membrane-bound enzymes.     

Effects of levonorgestrel on enzymes responsible for synthesis of triacylglycerols in rat liver

The effects of levonorgestrel treatment (4 micrograms/day per kg body weight 0.75 for 18 days) on rate-limiting enzymes of hepatic triacylglycerol synthesis, namely glycerol-3-phosphate acyltransferase and phosphatidic acid phosphatase were investigated in microsomal, mitochondrial and cytosolic fractions of rat liver. Levonorgestrel treatment resulted in a significant reduction (26%) of hepatic microsomal glycerol-3-phosphate acyltransferase specific activity. Hepatic mitochondrial glycerol-3-phosphate acyltransferase specific activity was unchanged. Levonorgestrel treatment also significantly reduced (by 20%) the specific activity of hepatic microsomal magnesium-independent phosphatidic acid phosphatase. However, magnesium-dependent phosphatic acid phosphatase specific activities in microsomal and cytosolic fractions were unaffected. Cytosolic magnesium-independent phosphatidic acid phosphatase activity was also unchanged. These studies are consistent with the view that levonorgestrel lowers serum triacylglycerol levels, at least in part, by inhibition of the glycerol-3-phosphate acyltransferase (EC 2.3.1.15) step in hepatic triacylglycerol synthesis.     

Barbiturate and anticonvulsant treatment in relation to osteomalacia with haemodialysis and renal transplantation.

Among 39 patients treated by regular haemodialysis for four years or more pathological fractures and histological evidence of osteomalacia were significantly more common in those taking barbiturates. Out of 58 transplant recipients surveyed after one year, seven had osteomalacia; four of these had been taking phenobarbitone and phenytoin and one had taken barbiturates alone. Sedatives and other drugs such as phenobarbitone and phenytoin that induce hepatic microsomal enzymes should probably be avoided when possible in patients with chronic renal failure and after transplantation.     

Effect of cyclosporine on parasitemia and survival of Plasmodium berghei infected mice

Cyclosporine triggers suicidal erythrocyte death or eryptosis, which is characterized by cell shrinkage and exposure of phosphatidylserine at the erythrocyte surface. The present study explored whether cyclosporine influences eryptosis of Plasmodium infected erythrocytes, development of parasitemia and thus the course of the disease. Annexin V binding was utilized to depict phosphatidylserine exposure and forward scatter in FACS analysis to estimate erythrocyte volume. In vitro infection of human erythrocytes with Plasmodium falciparum increased annexin binding and decreased forward scatter, effects potentiated by cyclosporine (> or = 0.01 microM). Cyclosporine (> or = 0.001 microM) significantly decreased intraerythrocytic DNA/RNA content and in vitro parasitemia (> or = 0.01 microM). Administration of cyclosporine (5 mg/kg b.w.) subcutaneously significantly decreased the parasitemia (from 47% to 27% of circulating erythrocytes 20 days after infection) and increased the survival of P. berghei infected mice (from 0% to 94% 30 days after infection). In conclusion, cyclosporine augments eryptosis, decreases parasitemia and enhances host survival during malaria.     

Effect of phenobarbitone on the nucleocytoplasmic transport of ribonucleic acid in vitro.

The transport of nucleic acids from the nucleus to the cytoplasm is a potential site for modification of normal cellular processes by drugs and hormones. In this study the effect of phenobarbitone on nucleocytoplasmic transport of ribosomes was measured in an assay system in vitro. The transport of radioactive ribosomes from isolated rat hepatic nuclei to unlabelled post-microsomal supernatant was measured in rats treated with 80 mg of phenobarbitone/kg body wt. or saline 3h before death. With either treatment, transport was linear with time, and dependent on temperature and the presence of ATP. However, phenobarbitone treatment increased transport of ribonucleoproteins over saline-treated animals nearly twofold. The effect of phenobarbitone was mediated through the cytosol, but was not the result of altered stability of the RNA transported to the cytosol. Cycloheximide (5 mg/kg body wt.) given 3.5 h before death inhibited the stimulation of transport by phenobarbitone. The data indicate that phenobarbitone increased the transport of RNA by stimulating the synthesis of cytosol factors that regulate transport of RNA from the nucleus.