In vivo wound healing activity of the methanolic extract and its isolated constituent, gulonic acid gamma-lactone, obtained from Grewia tiliaefolia

Grewia tiliaefolia is a subtropical tree, its stem bark is widely used in traditional Indian medicines to heal chronic wounds, gastric ulcers, burning sensation, itching and other allergic ailments. Bioassay-directed fractionation and chromatography of the methanolic extract of G. tiliaefolia stem bark has resulted in the isolation of gulonic acid gamma-lactone. The methanolic extract and the isolated constituent were studied for their potency on three different cutaneous wound models, VIZ., excision, incision and dead space wounds in Wistar rats. In the excision wound model, healing was assessed by the rate of wound contraction and period of epithelisation. In the incision wound model, the degree of healing was analysed by determining the skin breaking strength. In the dead space wound model, the parameters used to confirm the healing process were weight of granulation tissue, its tensile strength, hydroxyproline content and histological studies. The extract as well as the constituent demonstrated wound healing activity. Topical application of gulonic acid gamma-lactone (0.2% w/w ointment) caused faster epithelialisation with 94.02% wound contraction on day 16 post-wounding, while in control animals the duration of healing was extended up to 22 days with 79.53% wound contraction. The tensile strength of the incision wound was significantly increased (561.12 +/- 5.18 g) compared to the control (327.63 +/- 6.37 g). In the dead space wound model, a significant increase in weight, tensile strength and hydroxyproline content of the granuloma tissue was observed following oral administration of gulonic acid gamma-lactone (60 mg/kg). Histology of the granuloma tissue showed increased collagenation and the absence of monocytes. The wound healing effect was compared with that of the standard skin ointment nitrofurazone. The results of this investigation provide supportive scientific evidence for the medicinal use of G. tiliaefolia for healing of cutaneous wound.

Pulmonary toxicity of thuringiensin administered intratracheally in Sprague-Dawley rats

The purpose of this work is to evaluate the pulmonary toxicity of purified thuringiensin in Sprague-Dawley rats. Rats were intratracheally instillated with 0, 0.4, 0.8, 1.6, 3.2, 6.4 and 9.6 mg/kg body weight of thuringiensin. The results indicated that the acute pulmonary LD(50) of thuringiensin for rats was 4.4 mg/kg. The total number of inflammatory cells and lactate dehydrogenase (LDH) activity in the bronchoalveolar lavage (BAL) fluid increased in a dose-dependent manner after thuringiensin instillation. Furthermore, an effective dose of 1.6 mg/kg was selected for the time course study of pulmonary toxicity. The treated animals showed a significant increase in the weights of the lungs, hydroxyproline levels in the lungs and total number of cells in BAL fluid 2, 4, 7, 14, 28 and 56 days after treatment. In comparison with the control, the total protein concentrations in BAL fluid were increased by 361, 615, 116, 41, 34 and 41%, after 2, 4, 7, 14, 28 and 56 days, respectively. The LDH activity in BAL fluid showed a significant increase after 1, 2, 4, 7, 14, 28 and 56 days. The increases in fibronectin levels were 164, 552, 490, 769, 335, 257 and 61% at the corresponding times, but neither tumor necrosis factor nor interleukin-1 increased. The treated rats presented abnormal histology including distributed inflammation in the bronchioles and alveoli, bronchial cellular necrosis on days 1 and 2, and areas of septal thickening with cellular infiltration and collagen deposit in the intestinal and alveolar spaces on days 4-56. Based on these biochemical and pathological parameters, intratracheal instillation of purified thuringiensin might cause significant pulmonary toxicity in rats.

Modification of analytical procedures for determining vitamin C enzyme (L-gulonolactone oxidase) activity in swine liver

Modifications of the analytical method to determine L-gulono-gamma-lactone oxidase (EC 1.1.8) enzyme activity were conducted in pig liver by evaluating the concentration of added substrate (L-gulono-gamma-lactone), glutathione, and various tissue sample-to-buffer ratios in the incubation mixture. Sampling different liver sites (lobes), the effect of different cooling temperatures of the liver immediately after collection, and the effect of tissue storage length on subsequent enzyme activity were evaluated. Our results demonstrated that 10 mM of substrate added to the reaction media maximized L-gulono-gamma-lactone oxidase enzyme activity, whereas increasing levels of glutathione did not greatly affect enzyme activity. High sample-to-buffer ratios resulted in higher L-gulono-gamma-lactone oxidase activities but sample analytical variations and background interferences were greater. A 1:4 tissue sample to buffer ratio (weight:weight) resulted in repeatable values, but the importance of maintaining the same ratio of the two components seems to be critical within an experiment. Expressing L-gulono-gamma-lactone oxidase enzyme activity on a liver protein rather than on a liver weight basis also resulted in more consistent results. No difference in liver L-gulono-gamma-lactone oxidase enzyme activities or ascorbic acid concentrations occurred between liver lobes. L-gulono-gamma-lactone oxidase enzyme activity from 0 to 90 day of storage was not affected when tissue samples were immediately frozen in liquid nitrogen, or placed on crushed ice. During a 90-day storage the oxidized form of ascorbic acid (dehydroascorbic acid) decreased (P < 0.01), the reduced (ascorbic acid) form increased (P < 0.01), while total ascorbic acid concentration remained constant.

[Comparison of the efficacy of two different iron supplements for anemia prevention in piglets]

In a randomized, confirmatory study performed between July and October 2000 the efficacy of two iron products in preventing iron deficiency anaemia was compared. A total of 102 newborn piglets from ten litters were treated intramuscularly with 200 mg iron as iron dextran per ml, or 200 mg iron as gleptoferron per ml. For true comparison, piglets within a litter of a sow were subdivided into pairs on the basis of birth weight (one pair of the two heaviest piglets, et cetera). Within a pair, treatment with the iron supplements was randomly allocated. One group of piglets was injected at an age of 1 day (experiment 1) and the other group of piglets was injected at an age of 3 days (experiment 2). The piglets were weighed and blood samples were taken at an age of 18 days (experiment 1) or at an age of 19 days (experiment 2). Average daily weight gain and haemoglobin concentrations of both treatment groups were compared. Both products were very effective in preventing anaemia. No significant differences could be found between the two formulations. It can be concluded that iron-dextran and gleptoferron can be used with similar effect for anaemia prevention in piglets.

Digital characteristics in commercial dairy herds fed metal-specific amino acid complexes

Five commercial dairy herds in Central New York fed metal-specific amino acid complexes were selected to evaluate digital characteristics. During the first year (period 1), herds were evaluated by a specific procedure by one individual. Three herds were not supplemented and two herds were supplemented with zinc methionine. During the subsequent year (period 2) all herds were switched to a combination of zinc methionine, copper lysine, manganese methionine, and cobalt glucoheptonate and evaluated in the same way as during period 1. There was no effect of period on incidence of heel erosion and interdigital dermatitis. During period 2, there was a reduced incidence of double soling, white line separation, sole hemorrhages, sole ulcers, and papillomatous digital dermatitis, and the incidence of wall ridges tended to be reduced compared with period 1. There was no effect of period on the incidence of abaxial wall lesions, digital arthritis, or foot rot, although the overall incidence of these disorders was low. During period 2, when cows were fed a combination of complexed trace minerals, there was a general reduction in the incidence of digital disorders associated with the laminitis syndrome complex compared with period 1; however, other time-related differences existed that may confound interpretation.

Immunoreactive TSH cells in the pituitary of female middle-aged rats after treatment with estradiol or calcium

The pituitary TSH cell structure of middle-aged (14-month-old) female Wistar rats chronically treated with estradiol dipropionate (EDP), calcium glucoheptonate (Ca) or with the combination of both was studied. TSH-producing cells were examined in the pituitary pars distalis using rabbit anti-rat beta-thyrotropin (TSH) serum and peroxidase-antiperoxidase immunohistochemistry. A stereological method for the determination of morphometric changes of the volume of TSH cells and nuclei as well as of their number and relative volume densities was used. All examined morphometric parameters in treated animals showed a significant decrease in comparison with immunoreactive TSH cells of the controls; the most significant decrease was observed in EDP-treated rats. These results together with structural features of immunoreactive TSH cells in the pituitary of middle-aged rats after chronic application of EDP or Ca indicate that both compounds inhibit these cells.

Effect of diet on growth and plasma ascorbic acid in chicks

Six experiments were conducted to study the effect of diet on growth and plasma ascorbic acid in chickens. D-Glucuronolactone failed to improve growth with either a crude yeast-fish meal diet or a purified diet based on casein and gelatin. With the purified diet, D-glucuronic acid and L-gulonolactone also failed to improve growth and did not influence plasma ascorbic acid levels. Dietary ascorbic acid improved growth of chicks with a purified diet in most cases, but not with a corn-soybean diet. Meat meal and fish meal caused slight increases in plasma ascorbic acid, whereas soybean meal, safflower meal, and cottonseed meal caused greater increases when used in a purified diet. Gulonolactone oxidase activity in the kidney was not different between chicks fed the purified or the corn-soybean diets, but was reduced by 0.1% dietary ascorbic acid. The mechanism for the increase in plasma ascorbic acid with the addition of soybean meal and other plant protein sources to the diet is not known.

Evaluation of sterically stabilized liposomes as a vehicle for targeting technetium-99m labelled radiopharmaceuticals

Sterically stabilized neutral liposomes (multilamellar vesicles) were prepared by sonicating phosphatidylcholine and cholesterol (molar ratio 4:1) film in phosphate buffered saline (50 mM, pH 7.4) containing 4% Tween 20. Tc-99m-GHA was incorporated in these liposomes by treating 0.5 ml of the suspension with lyophilized GHA kit (5 mg GHA and 250 micrograms SnCl2 x 2 H2O) followed by addition of 1 ml 99mTcO4- (1-3 mCi). The labelling yield was 60-70%. Tween 20 has provided significant stability of the radiolabel as compared to that without its addition, when radiolabelled liposomes were incubated in serum up to 24 h. With respect to Tc-99m-GHA alone, radiolabelled liposomes exhibited 4- to 6-fold greater radioactivity in the blood of rabbits (15 min-24 h). Comparison of biodistribution data of radiolabelled liposomes and Tc-99m-GHA in mice demonstrated a 10- to 12-fold greater hepatic accumulation of radiolabelled liposomes with respect to that of Tc-99m-GHA throughout the period of study (15 min-24 h), though their concentration in the kidneys was comparable.

Repression by sustained-release beta-glucuronidase inhibitors of chemical carcinogen-mediated induction of a marker oncofetal protein in rodents

The degree of induction of an oncofetal protein marker in rodents by selected chemical carcinogens has been correlated with changes in carcinogenicity induced by dietary D-glucaro-1,4-lactone (GL) based anticarcinogens. These potent anticarcinogens may act to increase the clearance of carcinogens as glucuronides through the inhibition of beta-glucuronidase. The sustained-release forms are particularly effective, 1.5 mmol/kg of GL maintaining serum beta-glucuronidase activity at or below 50% for only 1 h, while an equivalent amount of calcium glucarate (CGT) maintained this level of inhibition for over 5 h. CGT or other sustained-release inhibitors, when fed to rodents during administration of carcinogens that undergo glucuronidation, caused a marked reduction in the induction of the marker protein. For those systems where other markers of carcinogenesis were also assessed, it was determined that the inhibition of marker-protein induction was quantitatively similar to both the inhibition of binding of the carcinogen to DNA and the subsequent induction of tumors in target organs.

Permeability of human brain tumor to 99mTc-gluco-heptonate and 99mTc-albumin. Implications for monoclonal antibody therapy

The variable penetration of chemotherapeutic drugs into brain and tumor is more dependent upon lipid solubility than upon size. In contrast, the molecular weight of virus- and tumor-specific monoclonal antibodies appears to limit uptake. The authors have studied eight patients with malignant brain tumors in order to compare tumor uptake of an iodinated contrast agent evaluated by computerized tomography scanning with uptake of the low and high molecular weight imaging agents technetium-99m (99mTc)-glucoheptonate and 99mTc-albumin, respectively, measured by radionuclide brain scanning. The agent 99mTc-labeled albumin was chosen for evaluation because its molecular weight (68,000) is similar to that of the most clinically promising monoclonal antibody fragment, the immunoglobulin (Ig) G Fab monomeric fragment. The radionuclide brain scans in the eight patients showed highly variable permeability of brain tumor to these markers, with uptake of the high molecular weight marker in the tumor being much less than that of the low molecular weight radionuclide. A clinical implication of these studies is that the success of monoclonal antibody therapy in the treatment of malignant brain tumors may require techniques to increase permeability of the blood-brain barrier and blood-tumor barrier to protein.

Modulation of feeding by endogenous sugar acids acting as hunger or satiety factors

Endogenous sugar acids, 3,4-dihydroxybutanoic acid (2-deoxytetronic acid, 2-DTA) and 2,4,5-trihydroxypentanoic acid (3-deoxypentonic acid, 3-DPA), have been identified in the serum of fasted rats. Effects of these sugar acids on rat feeding behavior and neuron activity were investigated. Injections of 2-DTA (2.5 mumol) into the third cerebral ventricle of chronic rats suppressed food intake and single-neuron activity in the lateral hypothalamic area (LHA). Food consumption was reduced for 24 h, even in 72-h food-deprived rats. The same amounts of 3-DPA elicited feeding and increased LHA single-neuron activity with latencies of 6-8 min. Electrophoretically applied 2-DTA significantly and specifically suppressed activity of glucose-sensitive neurons in the LHA, whereas 3-DPA facilitated the activity. Nonglucose-sensitive LHA neurons were not affected by these sugar acids. The high correlation between modulation of feeding behavior and changes in LHA neuron activity after injection of these sugar acids suggested that 2-DTA may act as an endogenous satiety substance and 3-DPA as a hunger substance. The effects may be mediated through glucose-sensitive neurons in the LHA.

A subacute toxicity study on 99m Tc stannous Glucoheptonate injection

A subacute toxicity study on 99m Tc stannous glucoheptonate was performed with rats, dogs and rabbits, injected intravenously at ten to 100 times the human dose on a body weight basis. There were no abnormalities in the clinical status of any of the animals. No changes were found in urinalysis, blood chemistry or hematology in the rabbit nor in gross examination, renal histology or bone marrow smears in the rats and rabbits. Hepatic histology was also done. A focal area of necrosis in a liver of one rabbit that had been injected with 100 times the human dose was observed using light microscopy. Examination by electron microscopy in another group of rats and rabbits was prompted by the observation of that lesion. This revealed vacuolated and dilated smooth endoplasmic reticulum and degranulated and vesiculated rough endoplasmic reticulum in all the test livers. X-ray microanalysis indicates that the ultrastructural changes are linked to the deposition of tin.