Monoclonal antibodies to bovine growth hormone potentiate hormonal activity in vivo by enhancing growth hormone binding to hepatic somatogenic receptors

Administration of GH complexed with monoclonal antibodies (MABs) potentiates the in vivo actions of the hormone. In particular, growth and serum IGF-I concentrations of GH-treated hypophysectomized rats are increased by concomitant injection of anti-GH MABs. Among 37 anti-bovine GH (bGH) MABs, we selected one MAB with the most potentiating effects to investigate the mechanisms responsible for this phenomenon. Hypophysectomized rats were killed 18 h after a single s.c. injection of bGH (100 micrograms/rat), alone or complexed with increasing doses of MAB (4, 40, 400 micrograms/rat; MAB:bGH molar ratio: 0.005, 0.05, 0.5). IGF-I was measured by radioimmunoassay in acid-extracted sera and livers, whereas liver IGF-I mRNA was quantified by Northern blot hybridization. The in vivo occupancy of liver somatogenic (GH) receptors was derived from the determinations of total and free 125I-labelled bGH binding to liver homogenates treated with 4 mol MgCl2/l or water. Injection of MAB-bGH complexes enhanced body weight gain and raised serum IGF-I, liver IGF-I and liver IGF-I mRNA more than bGH alone (1.6-, 6-, 10- and 7-fold increases at the highest dose of MAB, compared with bGH alone; P < 0.001). These potentiating effects of the MAB were dose-dependent and significant potentiation of the growth response was already observed with the lowest dose of MAB. In vivo occupancy of liver GH receptors was markedly higher 18 h after injection of MAB-bGH complexes than after bGH alone, and this effect was also dose-dependent (receptor occupancy of 28%, 37% and 83% after 4, 40 and 400 micrograms of MAB respectively compared with 6% after bGH alone; P < 0.05, 0.05 and 0.001 respectively). In contrast, the in vitro binding of 125I-labelled bGH to liver homogenates was decreased in the presence of high doses of MAB. We conclude that low amounts of MABs complexed with bGH potentiate the stimulation by the hormone of liver IGF-I synthesis and secretion in a dose-dependent manner. These effects are mediated, at least in part, through changes in hormone-receptor interaction in vivo, leading to enhanced and/or prolonged binding of bGH to its somatogenic receptors.     

Regulation of gill cytosolic corticosteroid receptors in juvenile Atlantic salmon: interaction effects of growth hormone with prolactin and triiodothyronine

The potential effects of growth hormone (GH), prolactin (Prl), and triiodothyronine (T3) on gill Na+,K+-ATPase activity and corticosteroid receptor (CR) concentration (Bmax) and dissociation constant (Kd) were examined in juvenile Atlantic salmon (Salmo salar). Compared to controls, fish injected with GH (ovine, 5.0 microgram g-1) had significantly greater gill Na+,K+-ATPase activity after 7 and 14 days. Gill CR Bmax and Kd were significantly elevated on day 7, but not day 14. T3 also significantly increased CR Bmax. The effect of GH on CR Bmax was also additive with T3 (5.0 microgram g-1) treatment. There was a synergistic effect on CR Bmax when purified coho salmon GH (csGH, 0.1 microgram g-1) was injected in combination with T3 (1.6 microgram g-1). Prl (ovine, 5.0 microgram g-1; purified coho salmon, 0.1 microgram g-1) did not significantly alter gill CR Bmax. Although Prl limited the increase in CR Bmax by GH, the effect was not signicant. T3 and Prl did not have an effect on Kd. GH significantly increased gill Na+,K+-ATPase activity, T3 administration did not have a significant effect, and Prl-treated fish had significantly lower gill Na+,K+-ATPase activity. The results indicate that T3 acts additively with GH, while Prl has no effect in regulating CR Bmax. An increase in cytosolic CR by GH and T3, but not Prl, may regulate gill responsiveness to cortisol and be an important mechanism in the endocrine control of physiological changes during the parr-smolt transformation.     

Elemental iron does repress transferrin, haemopexin and haemoglobin receptor expression in Haemophilus influenzae

The present study was undertaken to determine the effect of GH administration on GH and IGF-I receptors in skeletal muscle compared with liver in growing pigs. Plasma IGF-I and GH-binding protein (GHBP) levels were also determined. Twelve Large White pigs (castrated males) were treated daily with 100 micrograms pituitary porcine GH (pGH) per kg body weight or vehicle for 41 days intramuscularly. Relative to controls, pGH administration increased plasma IGF-I concentrations by 3.3-fold. Administration of pGH had no effect on plasma GHBP levels. In liver, 125I-labelled bovine GH (bGH)-specific binding (P < 0.05) and GH receptor (GHR) mRNA levels (P < 0.05) were higher in pGH-treated than in control pigs. In longissimus dorsi (LD), 125I-labelled bGH specific binding did not differ significantly between the two groups while GHR mRNA levels (P < 0.05) were lower in pGH-treated than in control pigs. Administration of pGH had no effect on 125I-labelled bGH-specific binding and GHR mRNA levels in trapezius (TR). 125I-Labelled IGF-I-specific binding in liver was unaffected by pGH administration. Similarly, in liver, LD and TR, IGF-I receptor mRNA levels were not different between pGH-treated and control animals. It can be concluded that (1) GH binding and IGF-I receptor mRNA are not affected by GH in skeletal muscle, (2) GH influences GHR in a tissue-specific manner and (3) hepatic GHR and GHBP levels are not co-regulated.     

Transgenic rabbits overexpressing growth hormone develop acromegaly and diabetes mellitus

Transgenic rabbits expressing the bovine growth hormone (bGH) gene in liver and kidney were obtained to study the long-term effects of chronic exposure to GH in nonrodent animals. These rabbits presented high levels of bGH and insulin-like growth factor I in serum. In spite of chronic exposure to bGH, transgenic rabbits had similar body weight to controls. However, enlargement of the head and limbs and reduction of visceral fat were observed in these animals. They also showed marked hyperinsulinemia, hyperglycemia, and hypertriglyceridemia, indicating that they developed insulin resistance. Furthermore, serious histopathological alterations, including marked fibrosis, were observed in liver, kidney, and skeletal muscle. These anatomical, metabolic, and histological alterations closely resemble those found in patients with acromegaly. Thus, transgenic rabbits overexpressing GH may be a good model of the human disease.     

Mhc diversity in Pacific salmon: population structure and trans-species allelism

Geographic variation at an Mhc class I A1 exon was surveyed in 14 populations of coho salmon (Oncorhynchus kisutch) and 15 populations of chinook salmon (O. tshawytscha) inhabiting rivers of British Columbia, Canada. A total of 2,504 fish were sampled using denaturing gradient gel electrophoresis (DGGE), which distinguished 17 alleles in coho salmon and 20 alleles in chinook salmon. Heterozygosity at the A1 locus was moderately high for both coho (0.7) and chinook (0.6) salmon, but sequence divergence was low, with mean inter- and intraspecific nucleotide similarities of approximately 0.96. In a maximum parsimony tree, all of the observed alleles clustered into two trans-specific lineages. Within each lineage, coho and chinook alleles tended to fall into species-specific subclusters. Much of the intraspecific allelic variation within each lineage could be accounted for by nonsynonymous point mutation, indicative of balancing selection. The FST values for both coho (0.11) and chinook (0.13) salmon indicated that much of the allelic diversity was partitioned among populations. Neighbor-joining analyses of A1 allelic frequencies among coho and chinook salmon populations showed strong patterns of geographic differentiation similar to those based on neutral genetic markers such as microsatellite loci. Both natural selection and the salmonid zoogeographic history of frequent population bottlenecks have shaped the patterns of diversity observed at this and other Mhc exons in Pacific salmonids.     

Serum levels of erythropoietin as a novel marker reflecting the severity of diabetic nephropathy

Investigations were undertaken to observe the influence of technical grade carbofuran (CF) on the egg maturational processes of catfish, Heteropneustes fossilis (Bloch). Fish were exposed to sublethal doses (0.5, 1, and 2 mg/L) of CF for 30 days at 25 +/- 1 degrees C. Control fish were maintained in water. The gonado-somatic index (G.S. I. = ovarian weight x 100/body weight) of the fish, treated with 1 or 2 mg/L CF, was decreased significantly compared to that of the controls. The inhibition was almost at the same level in these doses. CF at the dose of 0.5 mg/L was found to be ineffective. From the histomorphological observations of the ovary, it was observed that CF altered both the area and the percentage occurrence of the various types of primary oocytes in the ovary compared to that of the control fish. The stage I primary oocytes were predominantly higher in CF-treated fish than stage II and stage III which was reversed in control animals. The degeneration of follicular walls, connective tissues and vacuolization in the ooplasm of the stage II and III oocytes were observed in CF-treated fish (0.5-2 mg/L). It appears that CF at sublethal concentrations inhibits oocyte maturational processes in catfish.     

Demonstration of tank effect on growth indices of juvenile rainbow trout (Oncorhynchus mykiss) during an ad libitum feeding trial

Growth indices were examined in 24 identically managed tanks, each containing 120 diploid juvenile rainbow trout (initial mean body weight, 9.3 g) during a 12-week study to examine tank effects associated with tank location in a multi user research facility. Growth indices included mean body weight, feed intake, feed conversion index, and specific growth rate. The null hypothesis that tank effect had no effect on growth over the 12-week period was rejected (P = 0.038), and mean weight in individual tanks differed by as much as 18.7%). During the study it was determined that the proximity of tanks to common-use walkways in the facility could affect growth indices. This was indicated by significant differences in the mean fish weights among blocks of tanks served by different header tanks after 4 (P = 0.001) and 8 (P = 0.024) week. The block containing tanks of fish with the highest them weight was nearest to the 2 common-use walkways in the facility. Fish in this block of tanks, compared with those in other blocks, had significantly greater feed intake but no significant differences in conversion efficiency. Compensatory growth, a well known growth attribute in fishes, diminished the difference in mean weight be tween these blocks of tanks by the end of the study. Comparison of paired ranks within header tank blocks indicated that fish in those located nearest to walkways had higher feeding rates over the 12-week period (P = 0.048), but less efficient feed conversion (P = 0.040) than did fish in matched tanks located farthest from walkways. However, there were no differences in mean weight of fish. Results of this trial document the risks involved in identifying fish in a tank as the experimental unit when treatments are administered to the tank of fish, the latter being the true experimental unit.     

Familial hypokalemic periodic paralysis. Clinical, diagnostic and therapeutic aspects

A model of induced lactation was modified to examine the effects of bovine prolactin (bPRL) and bovine placental lactogen (bPL) on mammary growth and differentiation. Thirty-two peripubertal, non-pregnant Holstein heifers were given daily s.c. injections of oestradiol (0.05 mg/kg) and progesterone (0.25 mg/kg) for 7 days to initiate mammary growth. Treatment with bromocriptine (40 mg/3 days) reduced serum PRL concentrations to approximately 25% of pretreatment levels, for the duration of the study. On the day following the last steroid injection, groups of eight heifers were given twice daily s.c. injections of either saline (negative control), recombinant bPRL (rbPRL; 80 mg/day) or recombinant bPL (rbPL; 80 and 160 mg/day) for 7 days. At the end of this period (day 15), growth and differentiation of the mammary glands were assessed. Treatment with rbPL increased total mammary DNA above control value by 50 and 60% for the 80 and 160 mg/day doses respectively. However, total DNA was not different for the control and rbPRL-treated groups. The blood serum concentration of alpha-lactalbumin was measured daily throughout the study and used as an index of mammary differentiation. Both rbPRL and rbPL stimulated mammary differentiation (i.e. induction of milk synthesis), although rbPRL appeared to be more potent than rbPL. These results indicate that rbPL is lactogenic in vivo and strongly suggest that bPL is a mammary mitogen.     

Expression of a novel piscine growth hormone gene results in growth enhancement in transgenic tilapia (Oreochromis niloticus)

Several lines of transgenic G1 and G2 tilapia fish (Oreochromis niloticus) have been produced following egg injection with gene constructs carrying growth hormone coding sequences of fish origin. Using a construct in which an ocean pout antifreeze promoter drives a chinook salmon growth hormone gene, dramatic growth enhancement has been demonstrated, in which the mean weight of the 7 month old G2 transgenic fish is more than three fold that of their non transgenic siblings. Somewhat surprisingly G1 fish transgenic for a construct consisting of a sockeye salmon metallothionein promoter spliced to a sockeye salmon growth hormone gene exhibited no growth enhancement, although salmon transgenic for this construct do show greatly enhanced growth. The growth enhanced transgenic lines were also strongly positive in a radio-immuno assay for the specific hormone in their serum, whereas the non growth enhanced lines were negative. Attempts to induce expression from the metallothionein promoter by exposing fish to increased levels of zinc were also unsuccessful. Homozygous transgenic fish have been produced from the ocean pout antifreeze/chinook salmon GH construct and preliminary trials suggest that their growth performance is similar to that of the hemizygous transgenics. No abnormalities were apparent in the growth enhanced fish, although minor changes to skull shape and reduced fertility were noted in some fish. There is also preliminary evidence for improved food conversion ratios when growth enhanced transgenic tilapia are compared to their non-transgenic siblings. The long term objective of this study is to produce lines of tilapia which are both growth enhanced and sterile, so offering improved strains of this important food fish for aquaculture.     

Structure and function of bovine growth hormone. Bovine growth hormone as an experimental model for studies of protein-protein interactions

Growth hormone (GH) is a polipeptide that controls the differentiation, growth and metabolism of many cell types, and is secreted from the hypophysis of all vertebrate species tested so far. Despite the overlapping evolutionary, structural, immunological and biological properties, it is well-known that GHs from distinct mammalian species have significant species-specific characteristics. The main purpose of this review is to highlight bovine GH (bGH) structural features related to its species-specific properties. Novel interest in bGH is also aroused by the advent of biotechnological methods for production of recombinant proteins. In fact recombinant bGH will have a great importance in veterinary medicine research and as a 'high tech' drug that needs to be monitored in zootechnical productions.     

Disease problems of salmonid fish in Japan caused by international trade

The author details the connection between disease outbreaks in salmonid fish and imports of salmonid eggs into Japan since the 1950s. The following diseases and species are involved: -infectious pancreatic necrosis in rainbow trout (Oncorhynchus mykiss) -infectious haematopoietic necrosis in sockeye ( of 'kokanee') salmon (O. nerka) and masu salmon (O. masu) -cold water disease, erythrocyte inclusion body syndrome, and bacterial kidney disease (caused by Renibacterium salmoninarum) in coho salmon (O. kisutch), ayu (Plecoglossus altivelis), rainbow trout and masu salmon. The author also discusses the strategies aimed at controlling the risk of disease spread through international trade in salmonid fish and fish products in Japan. Essential in these strategies are the following actions: -exchange of information on controlling disease problems -studies to establish standard methods to identify or detect fish pathogens -fish health certification.     

Choice of method for laparoscopic hernioplasty

In zebrafish it is possible to create viable diploid fish whose genomic DNA is derived only from the female parent (parthenogenesis) or, as was more recently shown, only from the male (androgenesis). Androgenesis requires holding zebrafish eggs in an inactivated state in vitro for an hour or more. Previously this was achieved by placing the zebrafish eggs in ovary fluid obtained from rainbow trout (Onchorhynchus mykiss) or coho salmon (Onchorhynchus kisutch). Here we report that adding bovine serum albumin (BSA) to Hank's buffered saline prevents zebrafish egg activation in vitro. Of the zebrafish eggs placed in Hank's saline plus 0.5% BSA, 85% +/- 8.7% were fertilizable after incubation for one hour at room temperature (23 degrees C). Longer incubations are possible but with lower efficiency of fertilization. This technique not only could facilitate androgenesis, but also might be useful when making transgenics by microinjection, when performing antibody or RNA injections before fertilization, or for studying the mechanisms of egg activation in zebrafish.     

Occurrence of ateliosis in Japanese Black calves and their secretory function of growth hormone

Unthrifty calves occurred sporadically in Japanese Black (beef cattle) in an area in northeastern Japan. The states of unthrifty development, pedigree, clinico-biochemistry and the secretory function of bovine growth hormone (bGH) in pituitary were investigated. The total cholesterol concentration and CK, AST and LDH activities in the serum showed higher values than those of control calves. Basal bGH concentrations in the serum and bGH secretory reactivity in the insulin tolerance test (ITT) were showed to be significantly lower than those of the control calves. Furthermore, sperm donated from a specific bull had been used for these unthrifty calves. This study suggested that the present occurrence of unthrifty calves represented ateliosis possibly caused by congenital hypopituitarism which decreased of bGH secretory function.     

Combined insulin-like growth factor-1 and growth hormone improves weight loss and wound healing in burned rats

The anabolic effects of growth hormone (GH) in burned patients appear to act both directly and through insulin-like growth factor-1 (IGF-1). We, therefore, hypothesize that exogenous GH plus IGF-1 will attenuate increases in metabolism and lean muscle wasting while promoting wound healing. MATERIALS AND METHODS: Rats, each weighing 440-470 g, were given a 35% total body surface area, full-thickness scald burn and divided into four groups to receive placebo (burned controls), bovine GH (2.5 mg/kg/day), IGF-1 (2.0 mg/kg/day), or bovine GH plus rhIGF-1 (2.5 + 2.0 mg/kg/day), respectively, for 8 weeks. RESULTS: Total body weight gain after 8 weeks averaged 110 g for GH plus IGF-1 compared with gains of 49 and 11 g for GH or IGF-1 alone, respectively. Burned controls lost 24 g. Metabolic rates were significantly reduced in all groups receiving growth hormones. Gastrocnemius muscle dry weight was significantly increased in those receiving GH plus IGF-1 compared with GH and IGF-1 alone or burned controls (p < .01). CONCLUSIONS: Data show that GH plus IGF-1 synergistically increased lean muscle weight, total body weight, and was more effective in re-epithelialization of the burn wound than either GH or IGF-1 alone.     

Gastrodin and p-hydroxybenzyl alcohol facilitate memory consolidation and retrieval, but not acquisition, on the passive avoidance task in rats

This study evaluated synthetic trehalose dicorynomycolate (S-TDCM), an immunomodulator, for its survival enhancing capacity and behavioral toxicity in B6D2F1 female mice. In survival experiments, mice were administered S-TDCM (25-400 micrograms/mouse i.p.) 20-24 hr before 5.6 Gy mixed-field fission-neutron irradiation (n) and gamma-photon irradiation. The 30-day survival rates for mice treated with 100-400 micrograms/mouse S-TDCM were significantly enhanced compared to controls. Toxicity of S-TDCM was measured in nonirradiated mice by locomotor activity, food intake, water consumption, and alterations in body weight. A dose-dependent decrease was noted in all behavioral measures in mice treated with S-TDCM. Doses of 100 and 200 micrograms/mouse S-TDCM significantly reduced motor activity beginning 12 hr postinjection with recovery by 24 hr. A dose of 400 micrograms/mouse significantly decreased activity within the first 4 hr after administration and returned to control levels by 32 hr following injection. Food and water intake were significantly depressed at doses of 200 and 400 micrograms/mouse on the day following drug administration, and were recovered in 24 hr. Body weight was significantly decreased in the 200 micrograms/mouse group for 2 days and in the 400 micrograms/mouse group for 4 days following injection. A dose of 100 micrograms/mouse effectively enhanced survival after fission-neutron irradiation with no adverse effect on food consumption, water intake, or body weight and a minimal, short-term effect on locomotor activity.     

Cyromazine toxicity in different laboratory strains of the tobacco hornworm (Lepidoptera:Sphingidae)

Three different strains of tobacco hornworm, Manduca sexta (L.), were treated with cyromazine ingestion of cyromazine-treated artificial diet or by intrahemocoelic injection. The effect of cyromazine on larval growth and the onset and severity of poisoning symptoms were similar in the wild-type green-pigmented strain and the white-pigmented mutant. Feeding times of 4 h or greater and injected doses of 22.6 micrograms/g larva or more resulted in lower weight gains than were observed with controls. Elongation caused by exposure was evident within 12-24 h. The incidence of cuticular rupture was 55 and 67% in the dietary exposure tests and 24 and 22% in the injection tests for the green and white strains, respectively. The response of the black strain to cyromazine differed by the route of administration. Like the other strains, dietary exposure times of 4 h or greater led to smaller weight gains than in the controls. Injected doses of 2.8 micrograms/g larva or more caused a decrease in the weight gain of the treated versus controls. A smaller proportion (21%) of black larvae consuming treated diet developed cuticular ruptures, whereas injected treatments had a higher incidence (87%). The differences in the pigmentation of the white and black strains had been linked to high and low juvenile hormone titers, respectively. The greater susceptibility of the juvenile hormone-deficient black strain raises the possibility that the mode of action of cyromazine involves a hormonal component. In a separate series of experiments, the poisoning symptoms of cyromazine were attenuated or eliminated by periods of starvation of 1-3 d following exposure to the chemical. Starvation for 3 d preceding treatment attenuated but did not eliminate signs of poisoning.     

Noxiustoxin 2, a novel K+ channel blocking peptide from the venom of the scorpion Centruroides noxius Hoffmann

A novel peptide called Noxiustoxin 2 (NTX2) was purified from the venom of the scorpion Centruroides noxius and characterized chemically and functionally. It is composed of 38 amino acid residues linked by three disulfide bridges and its primary structure is 61% identical to that of Noxiustoxin (NTX). It is not toxic to mice (using up to 200 micrograms/20 g mouse weight) and crustaceans (up to 30 micrograms/g of crayfish), but has a paralysing effect on crickets (30 micrograms/g animal). It displaces the binding of [125I]NTX to rat brain synaptosome membranes with a Ki of 0.1 microM, in comparison NTX has a Ki of 100 pM. Similarly, using single Ca2+ activated K+ channels of small conductance obtained from cultured bovine aortic endothelial cells it was shown that NTX2 is over two logarithm units less potent than NTX in producing 50% blockade of the probability of opening the channels. NTX2 is not recognized by a panel of six distinct monoclonal antibodies against NTX, however it is recognized by polyclonal antibodies raised in mouse, with native NTX. Primary structure comparison of both NTX and NTX2 suggests that the N-terminal segments of these peptides are important for channel affinity.     

Effects of dietary retinoic acid on skin papilloma and carcinoma formation in female SENCAR mice

Previously we have shown that dietary retinoids are essential for papilloma formation induced by either an initiation-promotion or a complete skin carcinogenesis protocol. The present study was conducted to further determine the effect of dietary retinoic acid (RA) on papilloma formation and the conversion of papillomas to carcinomas. Skin tumors were induced in 3 week old female SENCAR mice by an initiation-promotion protocol with one application of 20 micrograms of 7,12-dimethylbenz[a]anthracene (DMBA), followed by 20 weekly applications of 2 micrograms of 12-O-tetradecanoylphorbol-13-acetate (TPA). Mice were fed RA at one of the three doses: 0.3 (nutritionally marginal dose), 3 (near physiological) and 30 (pharmacological) micrograms/g of diet. Mice fed 30 micrograms of RA/g of diet had the same survival rate as the other two groups despite a lower body weight and all three groups had similar papilloma incidence, which reached 100% at age 18 weeks. Mice fed 3 micrograms of RA/g of diet had the highest papilloma yield (approximately 14 papillomas/mouse) of all groups and it peaked between weeks 18 and 38 of age. These papillomas later regressed such that mice from all three groups had about the same papilloma yield at week 44 of age. Mice fed 30 micrograms of RA/g of diet failed to develop any visible carcinoma, while mice fed 0.3 or 3 micrograms/g showed 1.9% conversion of papillomas to carcinomas. Therefore, dietary RA at 30 micrograms/g of diet inhibited the conversion of papillomas to carcinomas without affecting papilloma incidence. In addition, dietary RA at 30 and 0.3 micrograms/g of diet lowered papilloma yield.     

Inhibition of smooth muscle cell proliferation and neointimal growth by low-anticoagulant heparin

Low-anticoagulant heparin (LA-heparin) obtained by affinity chromatography on antithrombin III Sepharose inhibits the proliferation of cultured arterial smooth muscle cells in an in vitro bioassay system as effectively as standard heparin. A growth inhibition of smooth muscle cells of about 60% is achieved when LA-heparin or heparin is added to the culture medium to a concentration of 50 micrograms/ml. In normolipemic rats LA-heparin suppresses the formation of neointimal thickenings and stenosis after balloon catheter-induced deendothelialization of the carotid artery. In terms of mass a dose of 5 mg/kg body weight/d given subcutaneously twice daily one week before and 2 weeks after balloon injury the cross sectional area of the neointima is reduced to 36% as compared with the nontreated control group (100%). This 64% reduction is statistically highly significant (p < 0.001). After treatment with 0.5 mg LA-heparin/kg/d the reduction of the neointima was 11% (p < 0.05). At a dose of 5 mg/kg body weight single or repeated administrations of LA-heparin caused only a small and transient increase in activated partial thromboplastin time values. The results show that subcutaneous administration of LA-heparin very effectively prevents smooth muscle cell proliferation and balloon catheter-induced neointimal growth. The well tolerated systemic application of this chemically non-modified LA-heparin might justify clinical trials for prevention of restenosis after percutaneous transluminal coronary angioplasty or other invasive cardiovascular interventions without complications of bleeding.