Mutations in shaking-B prevent electrical synapse formation in the Drosophila giant fiber system

The giant fiber system (GFS) is a simple network of neurons that mediates visually elicited escape behavior in Drosophila. The giant fiber (GF), the major component of the system, is a large, descending interneuron that relays visual stimuli to the motoneurons that innervate the tergotrochanteral jump muscle (TTM) and dorsal longitudinal flight muscles (DLMs). Mutations in the neural transcript from the shaking-B locus abolish the behavioral response by disrupting transmission at some electrical synapses in the GFS. This study focuses on the role of the gene in the development of the synaptic connections. Using an enhancer-trap line that expresses lacZ in the GFs, we show that the neurons develop during the first 30 hr of metamorphosis. Within the next 15 hr, they begin to form electrical synapses, as indicated by the transfer of intracellularly injected Lucifer yellow. The GFs dye-couple to the TTM motoneuron between 30 and 45 hr of metamorphosis, to the peripherally synapsing interneuron that drives the DLM motoneurons at approximately 48 hr, and to giant commissural interneurons in the brain at approximately 55 hr. Immunocytochemistry with shaking-B peptide antisera demonstrates that the expression of shaking-B protein in the region of GFS synapses coincides temporally with the onset of synaptogenesis; expression persists thereafter. The mutation shak-B2, which eliminates protein expression, prevents the establishment of dye coupling shaking-B, therefore, is essential for the assembly and/or maintenance of functional gap junctions at electrical synapses in the GFS.

cDNA libraries from identified neurons

One approach to studying the changes in gene expression which underlie differentiation is to construct cDNA libraries from different tissues or at different stages of development. However, generating representative cDNA libraries from heterogeneous tissues such as the nervous system is often a real problem. Here, we describe a reproducible method for the construction of large and complex cDNA libraries from a few leech Retzius or P neurons (equivalent to about 50 pg of mRNA) using polymerase chain reaction-based technology. The libraries contain about 10(6) independent recombinants and are remarkably free from contaminating rRNA or polymerase chain reaction artefacts. Sequence analysis of randomly picked clones shows that the libraries contain a high proportion (more than 90%) of cDNAs larger than 500 b.p. As expected, many of the clones are novel, but two (alpha-tubulin and cyclophilin-A) have been extensively characterized in other species. To our knowledge, this is the first report of a cDNA library from identified neurons.

Mesenchyme to epithelium transition during development of the mammalian kidney tubule

Kidney epithelia have two separate origins. Collecting ducts develop in the manner of most glandular organs, by growth and branching of a bud derived from a pre-existing epithelium. Excretory tubules develop by a direct mesenchyme to epithelium transition (MET), which is induced by the tips of the developing collecting duct system as it invades a specialised area of mesenchymal cells. The process by which these metanephrogenic mesenchyme cells achieve MET can be divided into several stages; induction, acquisition of stem cell character, fate determination, condensation, epitheliogenesis, polarisation and maturation. Progress through these stages is regulated by 'checkpoints' at which permission to proceed requires specific signals. The stages of development are characterised by the expression of new combinations of genes that code for transcription factors (Hox genes, Pax genes, zinc finger proteins), signalling effectors (growth factors, Wnts, receptor tyrosine kinases) and morphoregulatory molecules (CAMs, cadherins, extracellular matrix ligands). This review summarises current knowledge about the molecular interactions that control MET in the kidney, and also about how their failure might result in Wilms' tumour, one of the most common cancers of childhood.

The effect of the desglycinyl metabolite of remacemide on cortical wedges prepared from DBA/2 mice

Remacemide hydrochloride is currently undergoing clinical trials for use as an anticonvulsant agent in the treatment of epilepsy. It is considered that the desglycinyl metabolite (FPL 12495AA) of the parent compound accounts for the majority of the anticonvulsant activity. In this study we have investigated the effects of FPL 12495AA on electrical activity in the cortical wedges prepared from audiogenic seizure-prone DBA/2 mice. FPL 12495AA at varying concentrations (50-200 microM) significantly reduced both the spontaneous depolarizations (IC50 102 microM) and the associated afterpotentials (IC50 50 microM) which are characteristic in this preparation under magnesium-free conditions. The compound also concentration-dependently reduced N-methyl-D-aspartate (NMDA)-induced depolarizations of the tissue (IC50 43 microM) and the antagonism by FPL 12494AA was not overcome by increasing NMDA concentrations. FPL 12495AA had no effect on (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA)-induced depolarizations. The results suggest that FPL 12495AA has a specific antagonistic effect on the NMDA receptor complex possibly through non-competitive inhibition at the phenycyclidine site in the ion channel. Such an action could contribute to its anticonvulsant properties.

Mechanisms of action of antiepileptic drugs

Depending on their mechanism of action, anticonvulsant drugs in clinical use may be divided into three groups: those drugs which facilitate gamma-aminobutryic acid (GABA)ergic neurotransmission; those which block neuronal ion channels; and those whose mechanism of action is unresolved. The compounds acting on GABAergic systems may be further subdivided into those which modulate transmission through chloride channels, e.g. the barbiturates and the benzodiazepines; those compounds, in particular vigabatrin, which reduce the degradation of GABA by blocking GABA transaminase; and those which inhibit the re-uptake of GABA into the presynaptic terminal. The other group of compounds whose mechanism of action is known are those which block neuronal ion channels. Blockage of voltage-operated sodium channels by lamotrigine, phenytoin or carbamazepine leads to decreased electrical activity and, probably, a subsequent reduction in glutamate release. Conversely, ethosuximide, blocks voltage-operated calcium channels, especially those which mediate calcium currents in thalamic neurones. Of those drugs in which the mechanism of action is unknown, sodium valproate is the prime example. An antagonistic action at the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor might also be a possibility, which could be the case with some of the newer compounds currently undergoing evaluation.

The effect of the desglycinyl metabolite of remacemide hydrochloride (FPL 12495AA) and dizocilpine (MK-801) on endogenous amino acid release from mouse cortex

1. In this study the effect of FPL 12495AA, the desglycinyl metabolite of remacemide hydrochloride and dizocilpine (MK-801), on potassium- and veratridine-stimulated release of neurotransmitter amino acids from mouse cortical slices was investigated. 2. Veratridine (20 microM) and potassium (60 mM) produced a preferential release of glutamate and aspartate. Potassium-stimulated release was calcium-dependent, while veratridine-stimulated release was only partially affected by removal of calcium from the medium. 3. FPL 12495AA significantly inhibited veratridine- and potassium-stimulated release of glutamate and aspartate. Lower concentrations of FPL 12495AA were needed to inhibit veratridine-stimulated release of glutamate (12.5 microM) than potassium-stimulated release (100 microM). 4. Dizocilpine significantly inhibited veratridine- and potassium-stimulated release of glutamate and aspartate at concentrations of 100 microM and above. 5. FPL 12495AA and dizocilpine both have an affinity for the ion channel subsite of the N-methyl-D-aspartate (NMDA) receptor. The reduction of potassium-stimulated release of glutamate and aspartate by FPL 12495AA and dizocilpine is probably due to NMDA receptor blockade. 6. FPL 12495AA inhibited veratridine-stimulated release at a concentration of 12.5 microM while dizocilpine was effective only at a concentration of 100 microM. This difference in efficacy is probably due to the higher affinity of FPL 12495AA compared to dizocilpine at the veratridine-binding site on the sodium channel.

Development, databases and the Internet

There is now a rapidly expanding population of interlinked developmental biology databases on the World Wide Web that can be readily accessed from a desk-top PC using programs such as Netscape or Mosaic. These databases cover popular organisms (Arabidopsis, Caenorhabditis, Drosophila, zebrafish, mouse, etc.) and include gene and protein sequences, lists of mutants, information on resources and techniques, and teaching aids. More complex are databases relating domains of gene expression to embryonic anatomy and these range from existing text-based systems for specific organs such as kidney, to a massive project under development, that will cover gene expression during the whole of mouse embryogenesis. In this brief article, we review selected examples of databases currently available, look forward to what will be available soon, and explain how to gain access to the World Wide Web.

Design and synthesis of potent retinoid X receptor selective ligands that induce apoptosis in leukemia cells

Structural modifications of the retinoid X receptor (RXR) selective compound 4-[1-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2- naphthyl)ethenyl]benzoic acid (LGD1069), which is currently in phase I/IIA clinical trials for cancer and dermatological indications, have resulted in the identification of increasingly potent retinoids with > 1000-fold selectivity for the RXRs. This paper describes the design and preparation of a series of RXR selective retinoids as well as the biological data obtained from cotransfection and competitive binding assays which were used to evaluate their potency and selectivity. The most potent and selective of the analogs is 6-[1-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalen-2- yl)cyclopropyl]nicotinic acid (12d; LG100268). This compound has proven useful for investigating RXR dependent biological pathways including the induction of programmed cell death (PCD) and transglutaminase (TGase) activity. Our studies indicate that the induction of PCD and TGase in human leukemic myeloid cells is dependent upon activation of RXR-mediated pathways.

A comparison between the stimulated and paroxysmal release of endogenous amino acids from rat cerebellar, striatal and hippocampal slices: a manifestation of spreading depression?

Spreading depression, which can be evoked by a variety of stimuli both in vitro and in vivo, is associated with profound changes in extracellular ion concentrations and enhanced release of neurotransmitter amino acids. We have observed a transient spontaneous release of amino acids in slice preparations obtained from rat cerebellum, striatum and hippocampus; this phenomenon has similar properties to stimulus-evoked spreading depression. Aspartate, glutamate, glutamine, serine, glycine and gamma-aminobutyric acid (GABA) release were potentiated during these episodes in all three brain regions, with a variable effect upon taurine release. When compared to glutamate release, a consistently high release of aspartate, glycine and serine was observed. Amino acid release, evoked by whole slice depolarization using veratridine (10-25 microM) or elevated potassium (35-60 mM) consistently enhanced glutamate release, and to a lesser extent aspartate release, but had negligible effect upon the other amino acids. Thus, the release profiles for spontaneous and depolarization-evoked release are markedly different. We suggest that the spontaneous release observed in brain slices represents a spreading depression-like phenomenon; the putative roles of the amino acids are discussed.

The effect of aspirin on haemostatic activity in the treatment of chronic venous leg ulceration

An increased rate of venous ulcer healing with the use of oral enteric-coated aspirin (300 mg) daily has been reported. Whether the effect of aspirin in this condition is related to its action on the haemostatic mechanism is unclear, and therefore this study aimed to assess the effect of aspirin on some haemostatic parameters in patients with chronic venous leg ulcers. A double-blind, randomized, placebo-controlled, parallel-group study of haemostatic activity and the effect of aspirin was implemented over a 4-month period. Twenty patients with venous leg ulcers, and 20 age- and sex-matched controls were studied. Patients received enteric-coated aspirin (300 mg) or placebo (one tablet) daily for 4 months, in addition to standardized local compressive bandaging (Setopress). Assessments made at recruitment, and at 2 and 4 months, included measurement of total ulcer surface area, haematological and biochemical screening, measurement of coagulation times, coagulation factor VIII:C (FVIII:C) and von Willebrand factor (vWF), and plasminogen activator inhibitor-1 (PAI-1) levels. Procoagulant activity was assessed by a computer-assisted technique, to determine the rate of thrombin production in vitro. Patients with venous ulcers had increased levels of fibrinogen (P < 0.01), FVIII:C (P < 0.05), vWF (P < 0.05) and PAI-1 antigen (P < 0.01) compared with controls. Shortening of the coagulation rate, shown by a reduction of the time to generate 50% maximal thrombin activity in seconds (T50), was seen in patients, in comparison with control subjects (P < 0.05). T50 was longer in patients receiving aspirin than those receiving placebo, reflecting prolongation of coagulation rate in the aspirin-treated group.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of insulin-induced hypoglycaemia on factor VIII:C concentrations and thrombin activity in subjects with type 1 (insulin-dependent) diabetes

The effect of insulin-induced hypoglycaemia on plasma coagulant activity was studied in 11 subjects with well-controlled, uncomplicated type 1 diabetes. Thrombin generation was determined in plasma by a computer ex-vivo assisted chromogenic method and by the activated partial thromboplastin time (APTT). In addition, factor VIII:C, thrombin-antithrombin III (TAT) complex and fibrinopeptide A (FPA) levels were measured. Hypoglycaemia induced a rise in mean (SD) factor VIII:C concentrations from a baseline level of 1.13 (0.32) IU/ml to a peak 15 min after onset of symptoms and they remained increased at 90 min [1.54 (0.57) and 1.5 (0.54) IU/ml, p < 0.001 respectively]. A corresponding reduction in time to generate 50% maximal thrombin activity occurred from a pre-insulin value of 56 (6) s to a minimum reading of 46 (7) s at 15 min (p < 0.001) and remained low at 90 min [48 (6) s, p < 0.001]. APTT shortened from 43.3 (4.8) s to 40.1 (4.6) s at 30 min (p < 0.001) but did not fall below the normal range (37.6-42.7 s) and no significant changes in TAT or FPA levels were noted. Factor VIII:C correlated inversely with time to generate 50% maximal thrombin activity and APTT (r = -0.580, p < 0.001; r = -0.673, p < 0.001, n = 66, respectively). The results show that the rise in plasma factor VIII:C levels induced by hypoglycaemia is accompanied by accelerated rates of generation of thrombin in contact-activated plasma, though concentrations of FPA and TAT remain unchanged, although TAT complexes are not a sensitive marker of in vivo thrombin generation.

Induction of early stages of kidney tubule differentiation by lithium ions

Kidney tubules develop by a mesenchyme-epithelium transition, normally induced by ureteric bud through a mechanism that remains obscure. Murine nephrogenesis in vitro has always required heterologous inducing cells. We have discovered that Li+ can elicit the early stages of epithelial differentiation in isolated nephrogenic mesenchyme. We have made detailed comparisons of the timing of morphoregulatory molecule expression between Li(+)-mediated induction and the traditional in vitro method using induction by spinal cord. Both followed the same program of early morphoregulatory molecule expression, though Li(+)-induced samples failed to progress into the later parts of the nephrogenic process. Mesenchymes induced by Li+ showed more DNA synthesis than controls, though less than those induced by spinal cord. Discovery of a chemical means to activate differentiation in the absence of heterologous tissue offers a new basis for studying molecular mechanisms regulating the early events of nephrogenesis, as well as for investigating transduction of inductive signals that initiate the process.

Towards a genetic basis for kidney development

Although it is not easy to investigate the regulatory basis of developmental processes in most mammalian tissues, the mouse kidney has several distinct advantages as a model system. Its development involves a wide variety of developmental processes that include induction, stem-cell regulation, a mesenchyme-to-epithelium transition, epithelial morphogenesis and pattern formation. Further, there are several genetic disorders associated with its development, much of nephrogenesis will take place in vitro and a significant start has been made in elucidating the regulatory molecules involved in its ontogeny. Here, we summarise current knowledge on how the various aspects of kidney development are controlled at the genetic level. For this, we have compiled a table showing when and where the more than forty regulatory genes thus far identified are expressed during nephrogenesis (this table being a subset of a database also containing information on structural and functional proteins expressed during nephrogenesis). The data on the regulatory genes demonstrate, in particular, the importance of the Wilms' tumour gene, WT1, in nephrogenesis, the growth-stimulating interaction between the hepatocyte growth factor and its receptor, c-met, and the differences between uninduced and induced metanephric mesenchyme. In an attempt to highlight those stable developmental pathways which underpin the formation of the kidney and to facilitate future work, we have identified possible checkpoints occurring during nephrogenesis (stages at which a positive signal is needed for development to continue). The data to hand suggest that such checkpoints occur when metanephric mesenchyme is established in the intermediate mesoderm, when induction takes place, when stem cells are activated and before mesenchyme aggregates to form nephrogenic condensations.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of sigma ligands on the release of glutamate from rat striatal slices

This study investigated the effects of sigma receptor ligands on the release of endogenous amino acid neurotransmitters from rat striatal slices. The effect of haloperidol on release in slices prepared from 6-hydroxydopamine lesioned animals was also tested. Haloperidol, the (+/-) reduced metabolite of haloperidol, rimcazole and ifenprodil specifically reduced potassium-stimulated release of glutamate with IC50 values between 20-60 microM. The release of aspartate, gamma-aminobutyric acid (GABA) and glycine was not affected. Haloperidol also reduced glutamate release from slices prepared from lesioned animals. The neuroleptic drug alpha-flupenthixol and the putative sigma receptor ligand R(+)3-(3-hydroxyphenyl)-N-(n-propyl) piperidine (3-PPP) had no effect on release. These effects of the sigma ligands show that the inhibition of glutamate release is specific to this amino acid and also that it is not due to dopamine receptor blockade as those ligands which have low affinity for dopamine receptors were also effective in reducing release. A presynaptic location for sigma receptor sites, possibly associated with ion channels, could account for the effects of these ligands on transmitter release.

Randomised trial of oral aspirin for chronic venous leg ulcers

The effect of oral aspirin on the healing rate of chronic venous leg ulcers was compared with that of placebo in a double-blind randomised trial. 20 subjects with chronic venous leg ulcers were randomised to daily enteric-coated aspirin 300 mg or placebo, and standardised compression bandaging. 4 months of treatment achieved ulcer healing in 38% of the patients receiving aspirin compared with 0% of those receiving placebo (p < 0.007). 52% of the aspirin-treated group showed significant reduction in ulcer size compared with 26% of placebo recipients (p < 0.007). Reduction in ulcer surface area was significantly better in the aspirin-treated group at 2 (p < 0.01) and 4 months (p < 0.002) compared with that in the placebo group.

cDNA libraries from a few neural cells

One of the most powerful approaches to the molecular analysis of differential gene expression is to construct cDNA libraries corresponding to different tissues or developmental stages, and then to enrich for genes expressed in a particular tissue or at a particular time by subtractive hybridisation. Our aim is to reduce the complexity of neuronal cDNA libraries by generating libraries from the mRNA of a single cell. The system chosen is the Retzius cell of the leech, a large neurone which can be unambiguously dissected out. A cDNA library was generated from one leech ganglion (containing about 400 neurons) by anchor 1-oligo dT priming, the addition of dG tails, second strand synthesis primed by an anchor 2-oligo dC primer, followed by PCR from the two anchor regions. XBaI and EcoRI sites were included in the respective anchor primers, between the dT or dC run and the PCR primer sequence, allowing high-efficiency directional cloning. Eight clones picked and sequenced at random gave five with some homology to a known protein and three novel genes. The average insert size in the library was 600 bp, 0.2% of the clones hybridised to repetitive DNA, and 20/30,000 clones gave signals with the Drosophila actin gene. This approach has now been extended to a few pooled Retzius cells.

Effects of cyclo-oxygenase inhibition upon glutamate release from rat cerebellum

Arachidonic acid has been proposed as a diffusible second messenger in the CNS with a pathophysiological role in epilepsy and stroke and a physiological role in long-term potentiation. These actions are possibly due to the ability of arachidonic acid to enhance extraneuronal glutamate concentration. In this present study we have investigated the effect of flurbiprofen, a cyclo-oxygenase inhibitor, on both potassium- and veratridine-stimulated release of glutamate from rat cerebellar slices. Flurbiprofen (100-500 microM) had no effect on basal release but significantly increased stimulated release. The NMDA receptor antagonist CPP abolished the flurbiprofen-induced potentiation to both modes of stimulation, whilst the metabotropic glutamate receptor antagonist, L-AP3, blocked potassium-stimulated enhancement but had a variable effect on veratridine-stimulated release.

Higher levels of microproteinuria in Asian compared with European patients with diabetes mellitus and their relationship to dietary protein intake and diabetic complications

Asian patients with diabetes have a higher prevalence of renal disease than their European counterparts. The aim of the study was to investigate the pattern of the renal excretion of proteins in 70 Asian and 70 European patients with diabetes and to relate it to dietary intake of protein and prevalence of diabetic complications. Compared with matched Europeans, Asian patients had an increased urinary excretion of albumin and transferrin (p < 0.02) with 14 Asians and 6 Europeans having significant microalbuminuria (> 30 micrograms min-1). In 12 Asians and all 6 Europeans this was associated with complications from diabetes, particularly vascular. Asian patients had significantly more ischaemic heart disease (p < 0.001) but less neuropathy (p < 0.001) and retinopathy (p < 0.05) than their matched European counterparts. Asian diets were lower in protein (median (range) Asian vs European: 12.5% (6-29%) vs 19% (11-27%); p < 0.01) and carbohydrate but higher in fat than European diets. There was no correlation between dietary protein intake and excretion of any of the urinary proteins measured. However, a significant correlation was found in Asians between protein intake and length of residence in the UK (p < 0.005). Unless ways to reduce complications can be found then future allocation of resources will need to take this into consideration in areas with large Asian communities.

The effect of neuropeptides on the release of neurotransmitter amino acids from rat striatum

Neuropeptide Y (NPY), peptide YY (PYY), and galanin are found throughout the central nervous system with appreciable levels occurring in the striatum. In this study we have investigated the effects of these peptides on the potassium-stimulated release of endogenous neurotransmitter amino acids from slices of rat striatum. The release of glutamate was significantly reduced by nanomolar concentrations of each peptide, whilst the release of aspartate, gamma-aminobutyric acid (GABA) and glycine was not affected. The reduction in release due to galanin (200 nM) was inhibited by glibenclamide (5 microM). These results support the view that NPY, PYY and galanin modulate neurotransmitter release possibly by a presynaptic action. The results with glibenclamide suggest that the action of galanin is mediated through an ATP-sensitive potassium channel.

Aprotinin reduces cardiopulmonary bypass-induced blood loss and inhibits fibrinolysis without influencing platelets

Cardiopulmonary bypass (CPB) induces a bleeding defect which leads to enhanced blood loss. A double-blind study was carried out comparing aprotinin with placebo in patients undergoing re-operation for heart valve replacement. The results confirm that aprotinin is effective at reducing such loss. In the placebo treated group, significant increases were observed, during CPB, in the plasma concentrations of fibrinolytic activity, tissue plasminogen activator antigen, D-dimer, and beta-thromboglobulin. Platelet counts fell within 5-10 min of the patients going onto CPB, but this could be accounted for by the dilutional effect of the extracorporeal circuit. Inhibition of responsiveness of platelets, as judged by aggregometry, was significant only at the end of bypass when collagen was the agonist and after protamine reversal when ristocetin was the agonist. CPB did not enhance the release, into the circulation, of glycocalicin (a proteolytic fragment of glycoprotein Ib). In the aprotinin-treated group, the formation of fibrin degradation products as measured by D-dimer was inhibited. However, aprotinin did not influence the change in platelet count, suppress beta-thromboglobulin release from platelets, prevent the inhibition of platelet function or influence the concentration of plasma glycocalicin during the study period. These observations confirm that CPB leads to a fibrinolytic state and less responsive platelets. This study also indicates that aprotinin-induced reduction in blood loss is associated with inhibition of plasmin-mediated fibrin digestion and that the mechanism by which aprotinin reduces blood loss is not via protection of platelets during CPB.

Modulation of calcium-dependent and -independent components of veratridine-evoked release of glutamate from rat cerebellum

The entry of Ca2+ into the presynaptic neuronal terminal is considered to be a prerequisite for exocytosis. However, reports suggest that a Ca(2+)-independent component of release can exist for some neurotransmitters. In this study we have used veratridine-stimulated release of glutamate from rat cerebellar slices to investigate Ca(2+)-dependent and -independent release. A 1-min pulse of veratridine (10 microM) induced release of glutamate in both Ca(2+)-replete and Ca(2+)-free ACSF. Both modes of release, however, could be elicited in a sequential manner following a single application of veratridine in Ca(2+)-free ACSF, with return to Ca(2+)-replete conditions 5 min post-pulse. This separation permitted the modulation of either, or both, phases of release. Apamin and dihydrokainate had little effect on Ca(2+)-independent release but produced enhancement of the Ca(2+)-dependent phase. Tetrodotoxin abolished both phases of release when applied with the veratridine pulse, but had no effect on the Ca(2+)-dependent phase alone. The Ca(2+)-dependent phase was partially sensitive to Co2+, although the Ca2+ channel blockers verapamil, amiloride, omega-conotoxin and ruthenium red were ineffective, suggesting a lack of involvement of L-, N- or T-type channels. The possible mechanisms mediating the Ca(2+)-dependent and -independent components of endogenous glutamate release from cerebellar slices are discussed.

The effect of short-term exercise on plasma procoagulant activity in patients with type II (non-insulin-dependent) diabetes and healthy volunteers

The effect of exercise on plasma coagulant activity was studied in 16 subjects with newly-diagnosed type II diabetes without vascular complications and 9 healthy volunteers. Generation of thrombin was determined by a computer-assisted chromogenic method and results expressed as time to generate 50% maximal thrombin activity (T50/s). In addition, APTT, factor VIII and thrombin-antithrombin III (TAT) complex levels were measured. Pre-exercise FVIII:C [mean (+/- SD)] was increased in diabetic compared to control subjects [1.5 (0.4); 0.9 (0.2) IU ml-1; (p < 0.001) respectively]. No significant differences in APTT, TAT or T50 were detected between the groups. Exercise induced a rise in FVIII complex, reduction of APTT [33 (2) s to 31 (2) s; (p = 0.004)] and T50 [58 (6) s to 53 (6) s; (p = 0.01)] in controls and an increase in FVIII complex but no significant changes in APTT or T50 in diabetic patients, with no change in TAT in either group. A greater increase in FVIII:C than vWF levels occurred in controls [0.2 (0.1); 0.1 (0.1) IU ml-1; (p = 0.005)] and patients [0.3 (0.4); 0.2 (0.1) IU ml-1; (p = 0.032)]. In patients, FVIII:C correlated inversely with APTT (r = -0.522, p = 0.038) and T50 (r = -0.592, p = 0.016). The results show that FVIII:C levels are increased at diagnosis in patients with type II diabetes without vascular disease but there is no enhancement of plasma procoagulant activity. In healthy individuals, exercise induced activation of coagulation which was not seen in patients, suggesting that it does not precipitate a state of accelerated thrombogenesis in subjects with uncomplicated type II diabetes.