Methylselenol release as a cytotoxic tool: a study of the mechanism of the activity achieved by two series of methylselenocarbamate derivatives

A molecular modeling study has been carried out on two previously reported series of methylselenocarbamate derivatives that show remarkable antiproliferative and cytotoxic in vitro activity, against a panel of human cancer cell lines. These derivatives can be considered as having been constructed by a selenomethyl fragment located over a carbon atom which is decorated with two carbamate moieties, both aliphatic and aromatic, one of them attached by a single bond to the central carbon atom, while the second is connected by a double bond. According to the data obtained, these derivatives can undergo a water-mediated nucleophilic attack on the carbons with marked electrophilic character, which leads to the rupture of C-Se and carbamate C-O bonds. The aliphatic derivatives, series 1, show an early release of methylselenol and a further release of hydroxyl derivatives (alcohols), whereas the aromatic carbamates, series 2, show an early release of phenols followed by the subsequent release of methylselenol. Thus, the activity of the compounds can be related to the progressive release of active fragments. The data that support this connection are related to the overall molecular topology, volume and surface area as well as to quantum parameters such as the relative electrophilic character of the target carbon atoms (measured in terms of positive charge values) or the bond order values, especially concerning the central C-SeCH3 bond and the carbamate ones. Moreover, the data obtained regarding the chromatographic behavior of some representative compounds confirm this proposal.

In vitro radical scavenging and cytotoxic activities of novel hybrid selenocarbamates

Novel selenocyanate and diselenide derivatives containing a carbamate moiety were synthesised and evaluated in vitro to determine their cytotoxic and radical scavenging properties. Cytotoxic activity was tested against a panel of human cell lines including CCRF-CEM (lymphoblastic leukaemia), HT-29 (colon carcinoma), HTB-54 (lung carcinoma), PC-3 (prostate carcinoma), MCF-7 (breast adenocarcinoma), 184B5 (non-malignant, mammary gland derived) and BEAS-2B (non-malignant, derived from bronchial epithelium). Most of the compounds displayed high antiproliferative activity with GI50 values below 10μM in MCF-7, CCRF-CEM and PC-3 cells. Radical scavenging properties of the new selenocompounds were confirmed testing their ability to scavenge DPPH and ABTS radicals. Based on the activity of selenium-based glutathione peroxidases (GPxs), compounds 1a, 2e and 2h were further screened for their capacity to reduce hydrogen peroxide under thiol presence. Results suggest that compound 1a mimics GPxs activity. Cytotoxic parameters, radical scavenging activity and ADME profile point to 1a as promising drug candidate.

The cannabinoid TRPA1 agonist cannabichromene inhibits nitric oxide production in macrophages and ameliorates murine colitis

BACKGROUND AND PURPOSE

The non-psychotropic cannabinoid cannabichromene is known to activate the transient receptor potential ankyrin-type1 (TRPA1) and to inhibit endocannabinoid inactivation, both of which are involved in inflammatory processes. We examined here the effects of this phytocannabinoid on peritoneal macrophages and its efficacy in an experimental model of colitis.

EXPERIMENTAL APPROACH

Murine peritoneal macrophages were activated in vitro by LPS. Nitrite levels were measured using a fluorescent assay; inducible nitric oxide (iNOS), cyclooxygenase-2 (COX-2) and cannabinoid (CB1 and CB2 ) receptors were analysed by RT-PCR (and/or Western blot analysis); colitis was induced by dinitrobenzene sulphonic acid (DNBS). Endocannabinoid (anandamide and 2-arachidonoylglycerol), palmitoylethanolamide and oleoylethanolamide levels were measured by liquid chromatography-mass spectrometry. Colonic inflammation was assessed by evaluating the myeloperoxidase activity as well as by histology and immunohistochemistry.

KEY RESULTS

LPS caused a significant production of nitrites, associated to up-regulation of anandamide, iNOS, COX-2, CB1 receptors and down-regulation of CB2 receptors mRNA expression. Cannabichromene significantly reduced LPS-stimulated nitrite levels, and its effect was mimicked by cannabinoid receptor and TRPA1 agonists (carvacrol and cinnamaldehyde) and enhanced by CB1 receptor antagonists. LPS-induced anandamide, iNOS, COX-2 and cannabinoid receptor changes were not significantly modified by cannabichromene, which, however, increased oleoylethanolamide levels. In vivo, cannabichromene ameliorated DNBS-induced colonic inflammation, as revealed by histology, immunohistochemistry and myeloperoxidase activity.

CONCLUSION AND IMPLICATIONS

Cannabichromene exerts anti-inflammatory actions in activated macrophages - with tonic CB1 cannabinoid signalling being negatively coupled to this effect - and ameliorates experimental murine colitis.

Cannabidivarin-rich cannabis extracts are anticonvulsant in mouse and rat via a CB1 receptor-independent mechanism

BACKGROUND AND PURPOSE

Epilepsy is the most prevalent neurological disease and is characterized by recurrent seizures. Here, we investigate (i) the anticonvulsant profiles of cannabis-derived botanical drug substances (BDSs) rich in cannabidivarin (CBDV) and containing cannabidiol (CBD) in acute in vivo seizure models and (ii) the binding of CBDV BDSs and their components at cannabinoid CB1 receptors.

EXPERIMENTAL APPROACH

The anticonvulsant profiles of two CBDV BDSs (50-422 mg·kg(-1) ) were evaluated in three animal models of acute seizure. Purified CBDV and CBD were also evaluated in an isobolographic study to evaluate potential pharmacological interactions. CBDV BDS effects on motor function were also investigated using static beam and grip strength assays. Binding of CBDV BDSs to cannabinoid CB1 receptors was evaluated using displacement binding assays.

KEY RESULTS

CBDV BDSs exerted significant anticonvulsant effects in the pentylenetetrazole (≥100 mg·kg(-1) ) and audiogenic seizure models (≥87 mg·kg(-1) ), and suppressed pilocarpine-induced convulsions (≥100 mg·kg(-1) ). The isobolographic study revealed that the anticonvulsant effects of purified CBDV and CBD were linearly additive when co-administered. Some motor effects of CBDV BDSs were observed on static beam performance; no effects on grip strength were found. The Δ(9) -tetrahydrocannabinol and Δ(9) -tetrahydrocannabivarin content of CBDV BDS accounted for its greater affinity for CB1 cannabinoid receptors than purified CBDV.

CONCLUSIONS AND IMPLICATIONS

CBDV BDSs exerted significant anticonvulsant effects in three models of seizure that were not mediated by the CB1 cannabinoid receptor and were of comparable efficacy with purified CBDV. These findings strongly support the further clinical development of CBDV BDSs for the treatment of epilepsy.

Fifteen-year phenological plant species and meteorological trends in central Italy

The present study was carried out in a phenological garden in central Italy that contains vegetative clones of shrubs and trees common to several international phenological gardens, such as Cornus sanguinea L.; Corylus avellana L.; Ligustrum vulgare L.; Robinia pseudoacacia L.; Salix acutifolia Willd. and Sambucus nigra L. Vegetative plant growth monitoring was carried out weekly using common international keys: BBCH07, bud break and leaf unfolding; BBCH19, young unfolded leaf; BBCH91, adult leaves; BBCH93, beginning of leaf colouring. The phenological dates thus obtained provide a model of the development for these different species in relation to the 15-year period of observation (1997-2011). From a meteorological point of view, temperature and precipitation trends were studied, with the highest anomalies during the study period recorded during the first 2 months of the year (January, February). There was relative invariance in the manifestation of the open bud phase and the contemporary advance of the young open leaves phase, particularly from 2006. This was accompanied by shortening of the leaf opening period, which appeared due to more rapid spring temperature increases over the last few years. The advance tendency of the BBCH91 phase showed adult leaves from the first summer weeks with fully green foliage monitored for a long time. Generally, the autumn leaf colouring phase tended to remain constant, with the exception of Salix acutifolia and Sambucus nigra, for which, on the other hand, the first leaf development phases appeared to be most likely influenced by the photoperiod.

[The possible uses of balneotherapy in treating chronic venous insufficiency of lower limbs]

The Chronic Venous Insufficiency (CVI) of inferior limbs is a widespread disease, with an increasing incidence as a consequence of longer life expectance, life-style, obesity, smoking, use of drugs as oestrogens and progestins and working conditions. Medical therapy is still lacking for evidence of efficacy, and compression therapy is useful only in preventing a worsening of this condition. Surgical treatment is the only radical therapy effective for the advanced phases of the disease. In this context spa balneotherapy can be considered as a possible chance to improve some subjective and objective symptoms of CVI of inferior limbs, and to prevent worsening of this condition. The authors performed a review of the relevant scientific literature concerning the treatment of CVI of inferior limbs with mineral water balneotherapy, in order to evaluate its effects on objective and subjective symptoms and its effectiveness to prevent further worsening. We searched the PubMed/Medline, Cochrane Library, Embase, Web of Science databases for articles published between 1990 and 2011 on this topic. To this end, the authors selected few clinical-controlled and case-controlled studies; patients affected from CVI of inferior limbs were treated with balneotherapy at health spas with sulphureous, sulphate, salsojodic or salsobromojodic mineral waters. Baths in mineral waters were often associated with idromassotherapy and vascular pathway. Effects of spa balneotherapy are related to some aspecific properties, like hydrostatic pressure, osmotic pressure and water temperature, partly related with specific chemico-physical properties of the adopted mineral water. The controlled clinical studies on spa therapy showed significant improvement of subjective (such as itch, paresthesias, pain, heaviness) and objective symptoms (namely edema and skin discromias). These studies suggest that spa balneotherapy may give a good chance of secondary prevention and effective therapy of CVI of inferior limbs, but also that it needs of other clinical controlled trials.

Prokinetic effect of a standardized yarrow (Achillea millefolium) extract and its constituent choline: studies in the mouse and human stomach

BACKGROUND

Functional dyspepsia (FD) is a highly prevalent gastrointestinal disorder characterized by alterations in gastric motility. Yarrow (Achillea millefolium L., Fam Asteraceae) preparations are traditional remedies used to treat dyspeptic complaints. Herein, we investigated the effect of a standardized dry water extract obtained from A. millefolium flowering tops (AME) on gastric motility.

METHODS

The effect of AME on motility was evaluated on the resting tone of the isolated gastric antrum and on gastric emptying in vivo (phenol red meal method) both in control mice and in the model of cancer chemotherapy (cisplatin)-induced gastric abnormalities.

KEY RESULTS

The AME contracted mouse and human gastric strips and this action was unaffected by hexamethonium and tetrodotoxin, but strongly reduced by atropine. Among various chemical ingredients in yarrow, choline, but not the flavonoids rutin and apigenin, mimicked the action of AME. Furthermore, AME deprived of choline did not exert a contractile effect. In vivo, AME stimulated gastric emptying both in control and in cisplatin-treated mice, being more active in pathological states.

CONCLUSIONS & INFERENCES

It is concluded that (i) AME exerts a direct spasmogenic effect on gastric antrum; (ii) choline is the chemical ingredient responsible of such effect; (iii) the prokinetic effect of AME observed in vivo could provide the pharmacological basis underlying its traditional use in the treatment of dyspepsia.

Inhibitory effects of bromelain, a cysteine protease derived from pineapple stem (Ananas comosus), on intestinal motility in mice

BACKGROUND

Bromelain (BR) is a cysteine protease with inhibitory effects on intestinal secretion and inflammation. However, its effects on intestinal motility are largely unexplored. Thus, we investigated the effect of this plant-derived compound on intestinal contractility and transit in mice.

METHODS

Contractility in vitro was evaluated by stimulating the mouse isolated ileum, in an organ bath, with acetylcholine, barium chloride, or electrical field stimulation. Motility in vivo was measured by evaluating the distribution of an orally administered fluorescent marker along the small intestine. Transit was also evaluated in pathophysiologic states induced by the pro-inflammatory compound croton oil or by the diabetogenic agent streptozotocin.

KEY RESULTS

Bromelain inhibited the contractions induced by different spasmogenic compounds in the mouse ileum with similar potency. The antispasmodic effect was reduced or counteracted by the proteolytic enzyme inhibitor, gabexate (15 × 10(-6)  mol L(-1) ), protease-activated receptor-2 (PAR-2) antagonist, N(1) -3-methylbutyryl-N(4) -6-aminohexanoyl-piperazine (10(-4) mol L(-1) ), phospholipase C (PLC) inhibitor, neomycin (3 × 10(-3) mol L(-1) ), and phosphodiesterase 4 (PDE4) inhibitor, rolipram (10(-6)  mol L(-1) ). In vivo, BR preferentially inhibited motility in pathophysiologic states in a PAR-2-antagonist-sensitive manner.

CONCLUSIONS & INFERENCES

Our data suggest that BR inhibits intestinal motility - preferentially in pathophysiologic conditions - with a mechanism possibly involving membrane PAR-2 and PLC and PDE4 as intracellular signals. Bromelain could be a lead compound for the development of new drugs, able to normalize the intestinal motility in inflammation and diabetes.

Correlation between large-scale atmospheric fields and the olive pollen season in Central Italy

Olives are one of the largest crops in the Mediterranean and in central and southern Italy. This work investigates the correlation of the Olea europaea L. pollen season in Perugia, the capital city of the region of Umbria in central Italy, with atmospheric parameters. The aim of the study is twofold. First, we study the correlation between the pollen season and the surface air temperature of the spring and late spring in Perugia. Second, the correlation between the pollen season and large-scale atmospheric patterns is investigated. The average surface temperature in the spring and late spring has a clear impact on the pollen season in Perugia. Years with higher average temperatures have an earlier onset of the pollen season. In particular, a 1 degrees C higher (lower) average surface temperature corresponds to an earlier (later) start of the pollen season of about 1 week. The correlation between the pollen season and large-scale atmospheric patterns of sea level pressure and 500-hPa geopotential height shows that the cyclonic activity in the Mediterranean is unequivocally tied to the pollen season in Perugia. A larger than average cyclonic activity in the Mediterranean Basin corresponds to a later than average pollen season. Larger than average cyclonic activity in Northern Europe and Siberia corresponds to an earlier than average pollen season. A possible explanation of this correlation, that needs further investigation to be proven, is given. These results can have a practical application by using the seasonal forecast of atmospheric general circulation models.

Cannabinoids and gastrointestinal motility: animal and human studies

The plant Cannabis has been known for centuries to be beneficial in a variety of gastrointestinal diseases, including emesis, diarrhea, inflammatory bowel disease and intestinal pain. delta9-tetrahydrocannabinol, the main psychotropic component of Cannabis, acts via at least two types of cannabinoid receptors, named CB1 and CB2 receptors. CB1 receptors are located primarily on central and peripheral neurons (including the enteric nervous system) where they modulate neurotransmitter release, whereas CB2 receptors are concerned with immune function, inflammation and pain. The discovery of endogenous ligands [i.e. anandamide and 2-arachidonoyl glycerol (2-AG)] for these receptors indicates the presence of a functional endogenous cannabinoid system in the gastrointestinal tract. Anatomical and functional evidence suggests the presence of CB1 receptors in the myenteric plexus, which are associated with cholinergic neurons in a variety of species, including in humans. Activation of prejunctional CB1 receptors reduces excitatory enteric transmission (mainly cholinergic transmission) in different regions of the gastrointestinal tract. Consistently, in vivo studies have shown that cannabinoids reduce gastrointestinal transit in rodents through activation of CB1, but not CB2, receptors. However, in pathophysiological states, both CB1 and CB2 receptors could reduce the increase of intestinal motility induced by inflammatory stimuli. Cannabinoids also reduce gastrointestinal motility in randomized clinical trials. Overall, modulation of the gut endogenous cannabinoid system may provide a useful therapeutic target for disorders of gastrointestinal motility.

Inhibitory effect of salvinorin A, from Salvia divinorum, on ileitis-induced hypermotility: cross-talk between kappa-opioid and cannabinoid CB(1) receptors

BACKGROUND AND PURPOSE

Salvinorin A, the active component of the hallucinogenic herb Salvia divinorum, inhibits intestinal motility through activation of kappa-opioid receptors (KORs). However, this compound may have target(s) other than the KORs in the inflamed gut. Because intestinal inflammation upregulates cannabinoid receptors and endogenous cannabinoids, in the present study we investigated the possible involvement of the endogenous cannabinoid system in salvinorin A-induced delay in motility in the inflamed gut.

EXPERIMENTAL APPROACH

Motility in vivo was measured by evaluating the distribution of a fluorescent marker along the small intestine; intestinal inflammation was induced by the irritant croton oil; direct or indirect activity at cannabinoid receptors was evaluated by means of binding, enzymic and cellular uptake assays.

KEY RESULTS

Salvinorin A as well as the KOR agonist U-50488 reduced motility in croton oil treated mice. The inhibitory effect of both salvinorin A and U-50488 was counteracted by the KOR antagonist nor-binaltorphimine and by the cannabinoid CB(1) receptor antagonist rimonabant. Rimonabant, however, did not counteract the inhibitory effect of salvinorin A on motility in control mice. Binding experiments showed very weak affinity of salvinorin A for cannabinoid CB(1) and CB(2) and no inhibitory effect on 2-arachidonoylglycerol and anandamide hydrolysis and cellular uptake.

CONCLUSIONS AND IMPLICATIONS

The inhibitory effect of salvinorin A on motility reveals a functional interaction between cannabinoid CB(1) receptors and KORs in the inflamed--but not in the normal--gut in vivo.

The role of endocannabinoids in the regulation of gastric emptying: alterations in mice fed a high-fat diet

BACKGROUND AND PURPOSE

Endocannabinoids (via cannabinoid CB(1) receptor activation) are physiological regulators of intestinal motility and food intake. However, their role in the regulation of gastric emptying is largely unexplored. The purpose of the present study was to investigate the involvement of the endocannabinoid system in the regulation of gastric emptying in mice fed either a standard diet (STD) or a high-fat diet (HFD) for 14 weeks.

EXPERIMENTAL APPROACH

Gastric emptying was evaluated by measuring the amount of phenol red recovered in the stomach after oral challenge; CB(1) expression was analysed by quantitative reverse transcription-PCR; endocannabinoid (anandamide and 2-arachidonoyl glycerol) levels were measured by liquid chromatography-mass spectrometry.

KEY RESULTS

Gastric emptying was reduced by anandamide, an effect counteracted by the CB(1) receptor antagonist rimonabant, but not by the CB(2) receptor antagonist SR144528 or by the transient receptor potential vanilloid type 1 (TRPV1) antagonist 5'-iodoresiniferatoxin. The fatty acid amide hydrolase (FAAH) inhibitor N-arachidonoyl-5-hydroxytryptamine (but not the anandamide uptake inhibitor OMDM-2) reduced gastric emptying in a way partly reduced by rimonabant. Compared to STD mice, HFD mice exhibited significantly higher body weight and fasting glucose levels, delayed gastric emptying and lower anandamide and CB(1) mRNA levels. N-arachidonoylserotonin (but not rimonabant) affected gastric emptying more efficaciously in HFD than STD mice.

CONCLUSIONS AND IMPLICATIONS

Gastric emptying is physiologically regulated by the endocannabinoid system, which is downregulated following a HFD leading to overweight.

The use of phenological data to calculate chilling units in Olea europaea L. in relation to the onset of reproduction

The aim of this study was to develop a practical method to evaluate the effective relationship between the amount of winter chilling and the response expressed as the spring reproductive re-starting dates in the olive (Olea europaea L.). Two olive cultivars growing in a special olive orchard in Umbria (central Italy) were studied over a 3-year period (1998-2000): the cultivar Ascolana, typical of central Italy, and the cultivar Giarraffa, typical of southern Italy. The spring reproductive restarts were assessed using data from detailed phenological observations made on 60 trees of each cultivar in an effort to establish the exact date of reproductive bud swelling. The chilling phenomenon was evaluated by using 341 functions derived from a formula developed by researchers at Utah State University to calculate chilling units. The mathematical functions are defined, and show the very close relationship between the amount of winter chilling and the spring reproductive response in the two cultivars in the orchard studied. The results can be used to define the relationship between local climate and plant development, and the mathematical approach can be used to draw maps that can show the suitability of different cultivars on the basis of local climatic conditions.

Acute intoxication with orphenadrine and clozapine

This report describes a fatal intoxication with two different drugs: clozapine and orphenadrine. A 38-year-old man was found dead in the bedroom of his residence. Near the body were found various empty pharmaceutical boxes, employed in schizophrenic therapy, two of them containing clozapine and orphenadrine. High concentrations of clozapine and orphenadrine detected in blood, urine and gastric content were related to death. These compounds were identified and quantitated by liquid-liquid extraction followed by gas chromatographic/mass spectrometry (GC/MS) analysis.

Immunochemical studies on the cercarial-specific calcium binding protein of Schistosoma mansoni

Stage-specific expression of the mRNA encoding the cercarial-specific 8 kDa CaBP has been described previously. To gain information on possible function(s) of this protein we raised antibodies to the CaBP in rabbits immunized with a CaBP-TrpE fusion protein synthesized in bacteria. Western blots showed high levels of CaBP in cercariae and 3 h schistosomula, trace amounts in 24 h schistosomula, and none in miracidia sporocyst and adult worm, as found for the mRNA. The CaBP molecule has a short half-life (< or = 4 h) similar to that of the mRNA. Other experiments demonstrate that the CaBP may interact with a putative target molecule in a calcium-dependent manner to form a complex of 45 kDa. Immunogold electron microscopy showed CaBP in selected regions of cercariae and 3 h schistosomula: tegument, head gland, subtegumental cells, flame cells, intestinal wall and the body-tail junction. Other investigators have shown that the head gland and subtegumental cells synthesize and translocate granules to the tegument during transformation from cercariae (living freely in water) to schistosomula (residing in vertebrate host). These observations and the time-course of CaBP detection suggest that the CaBP synthesized in the head gland and subtegumental cells is translocated to the tegument where it plays a role in tegument modifications required for adaptation to parasite life in the host. CaBP was not found in muscles and mitochondria, suggesting that it is not involved in the rapid motility and aerobic metabolism characteristic of cercariae.

Temperature influence on differentiation and release of hazel pollen

The aim of the present work was to identify the classic phenological stages, and to understand its relation to catkin differentiation and growth, and its consequences for the start of pollination. Phenological observations and an aeropalynological survey on Corylus avellana, which is an example of an economically and allergologically interesting arboreal plant, were carried out during 1991-1992. The comparison between the different phenological phases and the aeropalynological data, showed that the pollen trap recorded hazel-pollen presence in the atmosphere immediately after the pollen release from the orchard. The start of catkin elongation in late winter, after the chilling requirement has been fulfilled, could be used to indicate the beginning of heat accumulation necessary for pollination.

[Inhibition of total and active E-rosettes mediated by serum from tubercular patients]

AIM

To study the effect of tuberculous patients' serum upon normal lymphocytes in order to determine possible inhibition factors of immune response.

PATIENTS AND METHODS

We studied total E-rosette formation (4 degrees C, RET) and active rosette formation (37 degrees C, REA) in tuberculous patients in different stages: mild (n:36), moderate (n:28), severe (n:24) and a control group of 32 patients. The same determinations were studied in normal circulating lymphocytes (LN) incubated before with serum from tuberculous patients (SP), serum of normal individuals (SN) and in Tc-199 medium.

RESULTS

The number of RET and REA in tuberculous patients of different stages were significantly lower to the ones of the control group (p less than 0.01, p less than 0.05). This differences were also found when we compare the number of RET and REA after the incubation of LN with SP and SN respectively (p less than 0.01, p less than 0.05).

SUMMARY

Tuberculous patients showed an impaired ability to form RET and REA. The incubation of normal lymphocytes with serum from tuberculous patients reduced significantly its capacity to form rosettes.

[Color science in shade determination for ceramometal]

The authors in this study analyse some elements of color science, necessary to an adequate shade choice for ceramo-metal systems. Some light's physical properties, such as reflection, refraction and metamerism, light sources, contrast's effects can determine a change of real color shade. Adoption of some practice devices allows an appropriate porcelain shade selection for give to final crowns a naturalness' character in armony with patient's dentition.

A study on airborne allergenic pollen content in the atmosphere of Ascoli Piceno

The results of 4 years (1981-1984) of monitoring airborne pollen concentration, using a volumetric trap, in the atmosphere of Ascoli Piceno (central Italy) are reported. Pollen production wasn't constant during the studied years, showing in 1982 and 1984 a very high concentration in comparison to 1981 and 1983. This is due to a dry period from April to June in 1982 and from June to July in 1984. We found that the most important allergenic pollen is Gramineae with a principal period of pollination occurring from April to July. After Gramineae, Parietaria plays an allergenic role frequently in association with the pollen of Olea, which is the most important allergenic pollen of all the trees in this area. From August to October we observed the pollination of mugwort, which was found in small quantities but nevertheless an offender in localized cases of pollinosis in Ascoli Piceno.

Spinal lesions due to hyperextension in ankylosing spondylitis

The authors review the literature and discuss the biomechanical aspects of extension fractures of the spine in ankylosing spondylitis and report 3 cases. They conclude that, although such lesions are rare, patients with ankylosing spondylitis who sustain such trauma must be subjected to thorough radiological examination. The milder lesions have a favourable prognosis, but those involving dislocation are extremely dangerous, both because of the frequent appearance of immediate or delayed medullary complications and because of the high incidence of pseudarthrosis.