3-nitropropionic acid oxidase from horseshoe vetch (Hippocrepis comosa): a novel plant enzyme

A novel enzyme that catalyses the oxygen-dependent oxidation of 3-nitropropionic acid (3NPA) to malonate semialdehyde, nitrate, nitrite and H2O2 has been purified from leaf extracts of the horseshoe vetch, Hippocrepis comosa, and named 3NPA oxidase. The enzyme is a flavoprotein with a subunit molecular mass of 36 kDa containing 1 molecule of FMN and exhibits little specificity for all nitroalkanes tested other than 3NPA (apparent Km 620 microM). The maximum enzyme activity in vitro was expressed at pH4.8 and was inhibited strongly by the products nitrate and nitrite. 3NPA oxidase activity was detected in green shoots, which also contain high concentrations of 3NPA, from plants grown with nitrate, ammonium or N2 as sources of nitrogen. Enzyme activity was absent from roots and cell cultures, neither of which accumulate high levels of 3NPA.

Embryonic development of the inner ear and otolith of the rainbow trout Oncorhynchus mykiss

The embryonic development of the inner ear, especially the sensory epithelia and otoliths in the rainbow trout Oncorhynchus mykiss, was studied by light and electron microscopy. Light microscopically, the auditory vesicle, saccular otolith and statoacoustic ganglion were first observed by 12 days after fertilization, while the utricular otolith appeared at 15 days after fertilization. Both the saccular and utricular maculae were more developed at 22 days after fertilization, and well developed by 27 days. The crista ampullaris of the horizontal canal was also developed at 27 days after fertilization, while the other cristae were not yet distinguished. Electron microscopically, vesicular structures and short microvilli were found on the sensory epithelia of the maculae by 15 days after fertilization. At 22 days after fertilization, the saccular otolith possessed 7 incremental layers, and developing cilia, microvilli, and aggregates of secretory materials also appeared on the apical surface of the sensory epithelia. At 27 days after fertilization, the apical surface of each hair cell was covered with a hair bundle consisting of a single kinocilium and a bundle of stereocilia. These findings are discussed with special regard to the environmental factors on early development in fishes.

Bioequivalency studies on tablet formulation of tetroxoprim and sulphadiazine

The paper describes a comparative bioavailability study on two tablet formulations containing 100 mg of tetroxoprim and 250 mg of sulphadiazine. The comparison was based on the estimated pharmacokinetic parameters from time--serum concentration profiles obtained following the administration of the tablets to 12 healthy volunteers. Statistical analysis performed on the parameters showed that the differences are statistically insignificant and the formulations are bioequivalent.

A recombinant-DNA-derived modification of human growth hormone (hGH44-191) with enhanced diabetogenic activity

A modified human growth hormone (hGH) that lacks the first 43 residues of the intact hormone was prepared by recombinant-DNA technology. For preparative purposes an additional alanine was made the amino terminal residue. Sequence analysis and tryptic peptide mapping combined with amino acid analyses confirmed the structure of the polypeptide. Less than 2% N-terminal methionine was detected. The hGH44-191 was estimated to be at least 10 times more active than hGH in producing glucose intolerance in obese yellow mice (Avy/A) and was equipotent to hGH in increasing serum free fatty acids in fasted, hypophysectomized rats. The peptide did not promote growth in hypophysectomized rats nor did it exhibit early (1h) insulin-like activity in fasted, hypophysectomized rats, as indicated by its failure to lower blood glucose and fatty acids. The modified hGH was inactive in the Nb-2 cell assay but was about one-third as active as hGH in stimulating the pigeon crop sac. In radioimmunoassays using 125I-labeled hGH and polyclonal antibodies to intact hGH, cross-reactivity of hGH44-191 was less than 1%. We conclude that removal of the amino terminal portion of hGH enhances its diabetogenic properties, and that this activity does not depend upon the ability to promote growth. Furthermore, the insulin-like activity can be separated from its diabetogenic action by deletion of the first 43 amino terminal residues. This is the first report of a modified hGH that has anti-insulin effects greater than hGH itself.

High-performance liquid chromatographic determination of methotrexate in plasma

A procedure for the determination of methotrexate in human plasma is reported. The analysis involved extraction of methotrexate as an ion pair in ethyl acetate. Reconstituted residue was analyzed using reverse phase C-18 column and a mobile phase consisting of acetate buffer (87%), methanol (6.5%), and acetonitrile (6.5%). The methotrexate recovery range was 95-97%. Theophylline was used as internal standard with a recovery of 96%. The intraday coefficient of variation for the assay ranged from 1.8-3.0%, while interday variation coefficient range was 3.5-3.7%. The method is selective, reproducible, and covers a wide range of methotrexate concentrations in patient's plasma.

Effects of hypophysectomy and the insulin-like and anti-insulin pituitary peptides on carbohydrate metabolism in yellow Avy/A (BALB/c x VY)F1 hybrid mice

The amino-terminal portion of human growth hormone, residues 1-43 (hGH1-43), has insulin-potentiating action, while a hyperglycemic pituitary peptide (HP), which co-purifies with human growth hormone (hGH), is antagonistic to the action of insulin. The effects of hGH, hGH1-43, and HP on glucose metabolism were assessed in young (4-5 weeks) and adult (6-8 months) hypophysectomized yellow Avy/A mice which lacked any interfering endogenous pituitary hormones, and compared with age-matched intact obese yellow Avy/A and lean agouti A/a mice. Treatment with hGH1-43 or HP did not promote body growth in hypophysectomized yellow mice; but after 2 weeks of treatment with hGH, there was a significant increase in body weight (P less than 0.05). Treatment with HP raised blood glucose and lowered insulin concentrations in obese yellow mice, but not in agouti or hypophysectomized yellow mice. The severely impaired glucose tolerance of the hypophysectomized yellow mice was improved by acute (60 min) and chronic (3 days) treatment with hGH1-43 as well as by 2 weeks of treatment with hGH; in contrast, HP had no effect. Glucose oxidation in adipose tissue from obese yellow mice was low and showed essentially no response to stimulation by insulin at doses lower than 1000 microunits/ml. Basal glucose oxidation rates in adipose tissue taken from agouti and hypophysectomized yellow mice were significantly higher (P less than 0.001) than those in tissue from obese yellow mice, and the rates responded significantly (P less than 0.05) to 100 microunits/ml insulin. The insulin binding affinities in liver membranes from agouti mice were higher than those from either obese or hypophysectomized yellow mice. The insulin receptor densities were similar in both agouti and obese yellow mice, but higher in hypophysectomized yellow mice (P less than 0.05). Treatment with hGH1-43 slightly increased, although not significantly, the insulin receptor density in yellow obese mice while hGH showed essentially no change. Therefore, hypophysectomy appeared to increase tissue response and decrease insulin resistance by increasing receptor numbers and lowering the circulating insulin levels. Furthermore, the insulin-like action of hGH was elicited directly in vivo by hGH1-43 in hypophysectomized yellow mice.

Potentiation of response to insulin and anti-insulin action by two human pituitary peptides in lean agouti A/a, obese yellow Avy/A, and C57BL/6J-ob/ob mice

Insulin-like and anti-insulin effects of human growth hormone (hGH) were examined by determining the effects of two peptides representing portions of the hGH molecule in lean agouti A/a and obese yellow Avy/A and ob/ob mice. The peptides were the amino terminal segment, residue 1-43 (hGH1-43), which has been shown to potentiate the response to insulin and another peptide, hyperglycemic peptide (HP), with unknown structure, which has anti-insulin activity. The anti-insulin component is an acidic low molecular weight peptide which co-purifies with hGH but was not recognized by antibodies to intact hGH and did not cross-react with anti-hGH1-43 antiserum. The purpose of these studies was to further understand the multiple actions of hGH and its acute and chronic effects on response to insulin. Injections of hGH1-43 dramatically enhanced the effect of insulin on glucose clearance of obese yellow Avy/A and ob/ob mice and increased the insulin-stimulated glucose oxidation in adipose tissue of yellow mice, but had no direct effect on blood glucose or insulin levels of either genotype. Administration of HP to obese yellow mice produced hyperglycemia and suppressed serum insulin concentrations. Tissues from lean agouti and obese yellow mice treated with HP in vitro showed decreased basal and insulin-stimulated glucose oxidation as well as decreased 14C incorporation into lipids. Chronic treatment of obese yellow and ob/ob mice with HP increased fasting blood glucose and impaired glucose tolerance. The effect of HP was more pronounced in obese yellow mice and the ob/ob mice were more sensitive to the diabetogenic actions of intact hGH. These data provide further evidence for the existence of two opposing biologic activities derived from disparate amino acid sequences in hGH. Additionally, the data indicate that assays using obese yellow Avy/A mice can distinguish the effects of hGH from those of the individual peptides to a greater degree than assays using obese ob/ob mice.

The growth factor from plerocercoid larvae of the tapeworm, Spirometra mansonoides, stimulates growth but is not diabetogenic

A factor produced by plerocercoids of the tapeworm Spirometra mansonoides is similar to human growth hormone (hGH) in that it stimulates body growth, binds to hGH receptors, cross-reacts with anti-hGH antibodies, and has lactogenic and insulin-like activities. The purpose of this study was to determine whether plerocercoid growth factor (PGF) is similar to hGH in expressing diabetogenic activity in the genetically obese (ob/ob) mouse. To determine an effective dose for use in the obese mice, the ability of daily injections of PGF to stimulate growth of phenotypically normal mice of the same strain was assessed in a 10-day weight gain assay. Injections of PGF stimulated a dose-dependent weight gain (r = 0.83) and 25 ng eq/day of PGF stimulated a response not significantly different from that produced by 100 micrograms of bovine growth hormone/day. Diabetogenicity was assessed using fasting blood glucose and glucose tolerance tests in obese mice that had been injected for 3 days with saline, hGH, or PGF. Human growth hormone caused a significant increase (P less than 0.005) in fasting blood glucose and glucose tolerance of the obese mice was impaired (P less than 0.01). All of the doses of PGF used to test diabetogenicity in the obese mice were at least twice that required to stimulate a maximal growth response in normal mice, yet none of the doses of PGF increased fasting blood glucose or decreased glucose tolerance. These results show that PGF was a potent growth stimulant but was not diabetogenic.

Bioequivalency of ranitidine tablets

The bioavailability of two brands of ranitidine tablets was studied in 10 healthy volunteers. Formulation factors were compared by performing disintegration, dissolution and content uniformity tests. Plasma concentrations of ranitidine were measured using a sensitive and precise high pressure liquid chromatographic (HPLC) procedure. Pharmacokinetic parameters were determined for both formulations and included: Cmax, AUCt, AUC infinity, tmax, t1/2 and the terminal rate of elimination (k). Statistical analysis revealed that differences between the brands were not significant. The two formulations can be considered to be bioequivalent.

In vitro insulin-like actions of the growth factor from the tapeworm, Spirometra mansonoides

In vitro actions of purified plerocercoid growth factor (PGF) were compared with those of insulin and human growth hormone (hGH) in adipose tissue from normal male rats. Insulin-like effects were measured by the ability of PGF, insulin, or hGH to stimulate oxidation of [U-14C]glucose to 14CO2, to stimulate lipogenesis, and to inhibit epinephrine-induced lipolysis. PGF and insulin stimulated significant increases in glucose oxidation and lipogenesis in adipose tissue that had not been preincubated as well as in tissue that had been preincubated. hGH stimulated insulin-like effects only in tissue that had been preincubated for 3 hr. Insulin, hGH, and PGF inhibited epinephrine-induced lipolysis of preincubated (3 hr) adipose tissue. hGH produced a dramatic lipolytic response in tissue freshly removed from normal rats but no dose of PGF was lipolytic. PGF did not displace 125I-insulin from its receptors on adipocytes but did competitively inhibit 125I-hGH binding to adipocytes. These results suggest that PGF has direct insulin-like actions which are initiated by binding a GH receptor, but PGF had no anti-insulin action and the insulin-like activity of PGF was unaffected by refractoriness of adipose tissue to GH.

Effects of the amino-terminal portion of human growth hormone on glucose clearance and metabolism in normal, diabetic, hypophysectomized, and diabetic-hypophysectomized rats

A naturally occurring pituitary peptide, human (h) GH-(1-43) potentiates insulin action. The present study has compared the effects of acute (30-60 min) and chronic (3-6 days) injections of synthetic hGH-(1-43), hGH, and insulin in normal, diabetic, hypophysectomized, and diabetic-hypophysectomized rats. Male rats (150-250 g) received injections of saline, insulin (50-200 mU), hGH (200 micrograms), or hGH-(1-43) (200-400 micrograms) with or without insulin. Hormone and glucose were injected simultaneously for glucose tolerance tests. Basal and insulin-stimulated [U-14C]glucose oxidation to 14CO2 in adipose tissue were measured in vitro after in vivo treatments; insulin release by isolated pancreatic islets was determined in vitro. Acute injections of hGH-(1-43) with insulin dramatically increased glucose clearance in diabetic (P less than 0.05) and hypophysectomized (P less than 0.01) rats. In diabetic-hypophysectomized rats acute injections of hGH-(1-43) significantly lowered the elevated basal blood glucose level (P less than 0.025) and stimulated [U-14C]glucose oxidation to 14CO2 in adipose tissue (P less than 0.05); it did not increase the glucose clearance rate during glucose administration. Chronic treatment of diabetic rats with hGH-(1-43) did not lower the elevated blood glucose level significantly, but it stimulated [U-14C]glucose oxidation to 14CO2 in adipose tissue; the oxidation was further stimulated by treatment with insulin. Chronic injections of hGH-(1-43) slightly lowered blood glucose levels in hypophysectomized rats (P less than 0.025) despite a diminished release in vitro of insulin from pancreatic islets (P less than 0.05). Therefore, these experiments show hGH-(1-43) to be an insulin potentiator that increases insulin-stimulated glucose clearance and glucose oxidation without an increase in insulin secretion, and they suggest that the peptide may have a physiological role in regulating carbohydrate metabolism.

Insulin-like effects in the rat of the purified growth factor from Spirometra mansonoides plerocercoids

The acute effects of injections of the human growth hormone-like factor purified from plerocercoids of the tapeworm Spirometra mansonoides on carbohydrate, lipid, and protein metabolisms were determined in intact rats. Male rats were injected ip with saline, insulin, or various doses of partially purified PGF. The rats injected with insulin had significantly reduced serum glucose concentrations but no dose of PGF caused a change in serum glucose levels. Insulin and PGF stimulated [14C]glucose and [14C]leucine oxidation to 14CO2 in adipose tissue and muscle and increased incorporation of both [14C]glucose carbons into lipids and [14C]leucine into protein in fat and muscle. The responses to PGF were dose-dependent and persisted after 3 hr of incubation in vitro. Injections of naloxone prior to injecting PGF to block the stress response did not prevent the stimulation of insulin-like responses by PGF. Therefore, PGF has intrinsic insulin-like activities in normal male rats.

Some biochemical effects of the growth hormone analogue produced by plerocercoids of the tapeworm Spirometra mansonoides on carbohydrate metabolism of adipose tissue from normal, diabetic, and hypophysectomized rats

Plerocercoids of Spirometra mansonoides produce a functional analogue of mammalian growth hormone (GH). Plerocercoid growth factor (PGF) mimics the growth-promoting actions of GH, but has not been shown to duplicate all of the actions reported for GH. The purpose of this study was to determine the effects of plerocercoid infection (chronic PGF treatment) on glucose metabolism of adipose tissue and to compare the effects to those elicited by insulin and GH in intact, diabetic, and hypophysectomized male rats. Groups of rats were constantly exposed to PGF (via plerocercoid infection) or injected twice daily with bovine GH, insulin, or saline for 10 days. Basal oxidation rates of [U-14C]glucose to 14CO2 in adipose tissue segments were measured in vitro immediately after tissue removal. Other aliquots of adipose tissue were preincubated in hormone-free medium for 3 hr prior to testing the ability of the tissue to respond to insulin or human GH (hGH) added in vitro. Adipose tissue from PGF-treated intact and hypophysectomized rats had significantly elevated basal glucose oxidation rates, and the tissue was sensitive to further stimulation by insulin or hGH. The results obtained with intact and hypophysectomized rats were essentially the same, indicating that the effects of PGF were not due to suppression of endogenous GH. The basal glucose oxidation rate in adipose tissue from diabetic rats was stimulated (P less than 0.01) by PGF, but the tissue was not sensitive to insulin added in vitro. Furthermore, PGF had no effect on body growth or blood glucose concentrations of diabetic rats.(ABSTRACT TRUNCATED AT 250 WORDS)