Early Biomarkers from Conventional and Delayed-Contrast MRI to Predict the Response to Bevacizumab in Recurrent High-Grade Gliomas.

BACKGROUND AND PURPOSE: The interpretation of the radiologic response of bevacizumab-treated patients with recurrent high-grade gliomas represents a unique challenge. Delayed-contrast MR imaging was recently introduced for calculating treatment-response-assessment maps in patients with brain tumors, providing clear separation between active tumor and treatment effects. We studied the application of standard and delayed-contrast MR imaging for assessing and predicting the response to bevacizumab. MATERIALS AND METHODS: Twenty-four patients with recurrent high-grade gliomas were scanned before and during bevacizumab treatment by standard and delayed-contrast MR imaging. The mean change in lesion volumes of responders (overall survival, ≥1 year) and nonresponders (overall survival, <1 year) was studied. The lesion volumes at baseline and the changes in lesion volumes 1 month after treatment initiation, calculated from standard and delayed-contrast MRIs, were studied as possible predictors of outcome. In scans acquired at progression, the average change in lesion volume from previous follow-up in standard and delayed-contrast MRIs was compared. RESULTS: Response and progression patterns were identified from the mean change in lesion volumes, depicted from conventional T1WI, delayed contrast-enhanced MR imaging, and DSC MR imaging. Thresholds for early prediction of response were calculated by using these sequences. For each predictor, sensitivity, specificity, positive predictive values, and negative predictive values were calculated, reaching 85.7%, 87.5%, 75%, and 93.3% for conventional T1WI; 100%, 87.5%, 77.8%, and 100% for delayed-contrast MR imaging; and 75%, 78.6%, 50%, and 91.7% for DSC MR imaging. The benefit of delayed-contrast MR imaging in separating responders and nonresponders was further confirmed by using log-rank tests (conventional T1WI, P = .0022; delayed-contrast MR imaging, P < .0001; DSC MR imaging, P = .0232) and receiver operating characteristic analyses. At progression, the increase in lesion volumes in delayed-contrast MR imaging was 37.5% higher than the increase in conventional T1WI (P < .01); these findings suggest that progression may be depicted more effectively in treatment-response-assessment maps. CONCLUSIONS: The benefit of contrast-enhanced MR imaging for assessing and predicting the response to bevacizumab was demonstrated. The increased sensitivity of the treatment-response-assessment maps reflects their potential contribution to the management of bevacizumab-treated patients with recurrent high-grade glioma.

Enhanced cholinergic transmission promotes recall in honeybees.

The involvement of the cholinergic system in learning and memory in honeybees has been well established using olfactory conditioning. We examined the effect of Methyl Parathion (MeP), an acetylcholinesterase inhibitor of the organo-phosphate family, on the learning and recall of visual and olfactory discrimination tasks in honeybees. One of our expectations was to observe the effects induced by both the nicotinic and muscarinic systems, as the blocking of acetylcholinesterase should induce an increase in the activity of both systems. We were also interested in knowing whether the type of tasks could influence the results. The visual tasks involved learning to discriminate the orientation of gratings in a Y-maze; the olfactory task involved learning to discriminate odours in a proboscis extension reflex (PER) paradigm. The results indicate that MeP treatment enhances recall of learned tasks in the visual and olfactory domains, but it does not affect the acquisition phase in either domain. Surprisingly, MeP treatment led to muscarinic-like effects but failed to mimic the nicotinic-like effects already described in relation to learning phases in honeybees. Implications for the role of cholinergic pathways in learning and memory and the nature of their involvement are discussed, and a hypothesis relating to the organisation of the cholinergic system and the relationship between the nicotinic and muscarinic systems in honeybees is proposed. The results are also discussed in terms of their ecotoxicological consequences.

Histamine mediates osteoclastic resorption only during the acute phase of bone loss in ovariectomized rats.

Short-term studies have shown that histamine is involved, via its H2 receptors (H2R), in the mediator network regulating trabecular bone loss in long bones of ovariectomized (OVX) rats. It is not known whether this effect of histamine persists over time or involves other skeletal sites. In this study, rats were maintained for 6 months postOVX and treated daily with saline or famotidine (10 mg kg(-1)), an H2R antagonist. At the end of the experimental period, femur trabecular bone mass was markedly decreased in OVX rats, whether or not they were treated with famotidine. In contrast, in the fourth lumbar vertebra, where bone loss starts later than in the femur, famotidine treatment attenuated the decline in trabecular bone volume, protected the trabecular architecture, maintained the thickness of the cortices and reduced the numbers of osteoclasts and tartrate-resistant acid phosphatase-positive preosteoclasts, whereas it had no influence on bone formation parameters. In vertebral bone marrow of OVX rats, the numbers of mast cells (MCs) and non-MC histamine-producing cells increased, while famotidine treatment significantly diminished both cell populations. These data show that H2R antagonism does not protect trabecular bone mass in the long term, and that short-term protection involves all bones. Histamine is involved during the early phase of strong osteoclastic resorption but not during the late phase of slower resorption, suggesting that different mediator networks control the two phases of destruction. Histamine would be part of the network mediating the early phase.

Uridine enhances neurite outgrowth in nerve growth factor-differentiated PC12 [corrected].

During rapid cell growth the availability of phospholipid precursors like cytidine triphosphate and diacylglycerol can become limiting in the formation of key membrane constituents like phosphatidylcholine. Uridine, a normal plasma constituent, can be converted to cytidine triphosphate in PC12 [corrected] cells and intact brain, and has been shown to produce a resulting increase in phosphatidylcholine synthesis. To determine whether treatments that elevate uridine availability also thereby augment membrane production, we exposed PC12 [corrected] cells which had been differentiated by nerve growth factor to various concentrations of uridine, and measured the numbers of neurites the cells produced. After 4 but not 2 days uridine significantly and dose-dependently increased the number of neurites per cell. This increase was accompanied by increases in neurite branching and in levels of the neurite proteins neurofilament M [corrected] and neurofilament 70. Uridine treatment also increased intracellular levels of cytidine triphosphate, which suggests that uridine may affect neurite outgrowth by enhancing phosphatidylcholine synthesis. Uridine may also stimulate neuritogenesis by a second mechanism, since the increase in neurite outgrowth was mimicked by exposing the cells to uridine triphosphate, and could be blocked by various drugs known to antagonize P2Y receptors (suramin; Reactive Blue 2; pyridoxal-phosphate-6-azophenyl-2',4' disulfonic acid). Treatment of the cells with uridine or uridine triphosphate stimulated their accumulation of inositol phosphates, and this effect was also blocked by pyridoxal-phosphate-6-azophenyl-2',4' disulfonic acid. Moreover, degradation of nucleotides by apyrase blocked the stimulatory effect of uridine on neuritogenesis. Taken together these data indicate that uridine can regulate the output of neurites from differentiating PC12 [corrected] cells, and suggest that it does so in two ways, i.e. both by acting through cytidine triphosphate as a precursor for phosphatidylcholine biosynthesis and through uridine triphosphate as an agonist for P2Y receptors.

GATE: a simulation toolkit for PET and SPECT.

Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics. This feature makes it possible to simulate time curves under realistic acquisition conditions and to test dynamic reconstruction algorithms. This paper gives a detailed description of the design and development of GATE by the OpenGATE collaboration, whose continuing objective is to improve, document and validate GATE by simulating commercially available imaging systems for PET and SPECT. Large effort is also invested in the ability and the flexibility to model novel detection systems or systems still under design. A public release of GATE licensed under the GNU Lesser General Public License can be downloaded at http:/www-lphe.epfl.ch/GATE/. Two benchmarks developed for PET and SPECT to test the installation of GATE and to serve as a tutorial for the users are presented. Extensive validation of the GATE simulation platform has been started, comparing simulations and measurements on commercially available acquisition systems. References to those results are listed. The future prospects towards the gridification of GATE and its extension to other domains such as dosimetry are also discussed.

Histamine participates in the early phase of trabecular bone loss in ovariectomized rats.

We have previously reported that cimetidine, a reference H2 receptor antagonist, attenuates the initial osteoclastic burst and subsequent trabecular bone loss induced by ovariectomy (ovx) in rats. This study was designed to determine whether these effects are specific to H2 antagonism. To this end, we compared the effects of two H2 receptor antagonists, cimetidine and famotidine. In addition, we analyzed the response of histamine-producing cells to these inhibitors. Seventy-two 90-day-old female Sprague-Dawley rats were ovariectomized or sham-operated, and received single daily intramuscular injections of cimetidine (125 mg/kg), famotidine (10 mg/kg), or vehicle. The animals were killed 14 days after surgery and their femurs were processed for histomorphometry. Trabecular bone volume was reduced by 30% in ovx rats and by 15% in cimetidine- and famotidine-treated rats. Architectural parameters were reduced by about 20% in ovx rats. Cimetidine and famotidine attenuated these consequences of ovx by about 50%. Trabecular connectivity was deteriorated by ovx, while cimetidine and famotidine attenuated this effect. Resorption parameters were increased by ovx, while cimetidine and famotidine prevented this increase. Kinetic bone formation parameters were increased by ovx, while cimetidine and famotidine had no influence. Neither cimetidine nor famotidine had any observable effect in sham-treated rats. Mast cell numbers increased by 250% in ovx rats and by only 40% in H2 antagonists-treated ovx rats. A resident histamine-positive, non-mast cell, population found in bone marrow was increased by 25% by ovx. Interestingly, cimetidine and famotidine reduced this population in both sham-operated and ovx rats, famotidine being more potent than cimetidine. These results show that H(2) receptor blockade partially prevents the consequences of castration on cancellous bone resorption in female rats, and strongly suggest that histamine participates in the mediator network regulating estrogen deficiency induced bone resorption. A large population of histamine-producing cells, which differ morphologically from mast cells and belong to an immature marrow population, may be a source of histamine in this model. The H(2) blockers targeted this population, and this effect appeared to explain the anti-resorptive action of the two drugs.

Effects of imidacloprid metabolites on habituation in honeybees suggest the existence of two subtypes of nicotinic receptors differentially expressed during adult development.

Habituation of the proboscis extension reflex (PER) in honeybees (Apis mellifera) is age-dependent. Very young bees (< or =7 days old) require significantly less trials to abolish the response to multiple sucrose stimulations than older bees (> or =8 days old). A nicotinic agonist, imidacloprid, modifies this behaviour by increasing the number of trials in < or =7-day-old bees and by decreasing it in older bees [Neurobiol. Learn. Mem. 76 (2001) 183.]. Here we tested our hypothesis that this effect is associated with a differential expression of two subtypes of nicotinic acetylcholine receptors (nAChRs). By testing the effects of six metabolites of imidacloprid, we show that two of them, olefin and 5-hydroxy-imidacloprid, modify the number of trials needed to habituate the PER in a contrasting manner. Olefin increases the number of trials in both age groups, whereas 5-hydroxy-imidacloprid decreases the number of trials, but only in 8-day-old individuals. We conclude that olefin and 5-hydroxy-imidacloprid are specific agonists of two subtypes of an nAChR that are differentially expressed during adult maturation of young honeybees. Olefin is the agonist of an nAChR expressed in both age groups, whereas 5-hydroxy-imidacloprid is the agonist of a late-onset nAChR that is activated in 8-day-old bees. The implications of this finding for the honeybee biology are discussed.

Short-term prevention of osteoclastic resorption and osteopenia in ovariectomized rats treated with the H(2) receptor antagonist cimetidine.

Ovariectomy rapidly induces strong osteoclast differentiation, leading to a marked loss of cancellous bone in the rat appendicular skeleton. As we found that histamine inhibition prevented periosteal bone resorption in rats, we tested the hypothesis that cimetidine, an H(2) receptor antagonist, prevents the osteoclastic burst and subsequent trabecular bone loss in this setting. Forty female Sprague-Dawley rats were ovariectomized (ovx) or sham-operated. Rats from each group received daily intramuscular injections of cimetidine (125 mg/kg per day) or vehicle. The animals were killed 14 days after surgery, and their femora were processed for morphometry. Cimetidine had no effect on serum estradiol levels in the control and ovx rats. BV/TV was reduced by 36% in the ovx rats, and by 10% in the cimetidine treated rats (p < 0.01). Tb.N and Tb.Wi were significantly reduced by 30% in the ovx rats and by 15% ovx-treated ones. OcS/BS did not change in the treated ovx rats, but increased 3.7-fold in the untreated ovx ones (p < 0.001). The N.Oc/TBPm increased markedly in the ovx rats (2.6-fold, p < 0.0001 vs. controls), but only slightly in the cimetidine-treated animals (+18%, p < 0.05 vs. controls), with a significant difference between the cimetidine-treated and -untreated ovx animals (p < 0.001). Cimetidine had no effect on these parameters in sham-operated animals. These results show that histamine inhibition by an H(2) receptor antagonist partially prevents the consequences of castration on cancellous bone, possibly by an action on osteoclast differentiation. Interestingly, cimetidine had no effect on basal resorption along trabecular bone. Histamine inhibition by H(2) blockers warrants further investigation in this model of osteopenia.

Discrepancy between acute and chronic toxicity induced by imidacloprid and its metabolites in Apis mellifera.

Imidacloprid is a systemic nitroguanidine insecticide that belongs to the neonicotinoid family. As an agonist of the acetylcholine receptor, it attacks the insect nervous system and is extremely effective against various sucking and mining pests. Oral acute and chronic toxicity of imidacloprid and its main metabolites (5-hydroxyimidacloprid, 4,5-dihydroxyimidacloprid, desnitroimidacloprid, 6-chloronicotinic acid, olefin, and urea derivative) were investigated in Apis mellifera. Acute intoxication by imidacloprid or its metabolites resulted in the rapid appearance of neurotoxicity symptoms, such as hyperresponsiveness, hyperactivity, and trembling and led to hyporesponsiveness and hypoactivity. For acute toxicity tests, bees were treated with doses of toxic compounds ranging from 1 to 1,000 ng/bee (10-10,000 microg/kg). Acute toxicity (LD50) values of imidacloprid were about 60 ng/bee (600 microg/kg) at 48 h and about 40 ng/bee (400 microg/kg) at 72 and 96 h. Out of the six imidacloprid metabolites tested, only two (5-hydroxyimidacloprid and olefin) exhibited a toxicity close to that of imidacloprid. Olefin LD50 values were lower than those of imidacloprid. The 5-hydroxyimidacloprid showed a lower toxicity than imidacloprid with a LD50 four to six times higher than that of imidacloprid. Urea also appeared as a compound of nonnegligible toxicity by eliciting close to 40% mortality at 1,000 ng/bee (10,000 microg/kg). However, no significant toxicity was observed with 4,5-dihydroxyimidacloprid, 6-chloronicotinic acid, and desnitroimidacloprid in the range of doses tested. To test chronic toxicity, worker bees were fed sucrose solutions containing 0.1, 1, and 10 microg/L of imidacloprid and its metabolites for 10 d. Fifty percent mortality was reached at approximately 8 d. Hence, considering that sucrose syrup was consumed at the mean rate of 12 microl/d and per bee, after an 8-d period the cumulated doses were approximately 0.01, 0.1, and 1 ng/bee (0.1, 1, and 10 microg/kg). Thus, all tested compounds were toxic at doses 30 to 3,000 (olefin), 60 to 6,000 (imidacloprid), 200 to 20,000 (5-OH-imidacloprid), and >1,000 to 100,000 (remaining metabolites) times lower than those required to produce the same effect in acute intoxication studies. For all products tested, bee mortality was induced only 72 h after the onset of intoxication.

Time-course of mast cell accumulation in rat bone marrow after ovariectomy.

We previously reported that mast cells accumulate in the tibia bone marrow of ovariectomized (OVX) rats. In this study, the timing of mast cell accumulation and osteoclast generation were compared to determine whether or not mast cell accumulation preceded osteoclast recruitment after ovariectomy. This may be significant because of the number of cytokines released by mast cells that are potentially active on resorption. Sprague-Dawley rats (120) aged 12 weeks were OVX or sham-operated, and killed on days 4, 7, 14, 28, and 56 postsurgery. Ten additional intact rats were used as baseline controls. Ovariectomy was confirmed by a sharp and sustained fall in serum estradiol. The loss in trabecular bone volume (BV/TV) began on day 7, reaching 80% on day 56 (P < 0.001 vs baseline controls). The number of osteoclasts (N.OC/TBPm) increased in the OVX rats between days 4 and 7 (+130%; P < 0.001), and continued rising to day 28. During the next month, it decreased greatly (-63%, P < 0.001 on day 56 vs day 28). In the sham-treated rats, few mast cells were scattered in the bone marrow (1.9 cells/mm2 in the baseline controls). Their number fluctuated during the experimental period, but at each time-point it was lower than in the OVX rats. They were predominantly (90%) of the mucosal subtype. In the OVX rats, their number doubled between days 4 and 14 (P < 0.001), reached 8.6 cells/mm2 on day 28 (a 5.4-fold increase compared with day 4 OVX rats), and plateaued for the next 4 weeks. OVX had no effects on mast cell subtypes. In conclusion, mast cell accumulation and osteoclast differentiation are precocious and concomitant; this does not support a direct role for mast cells in osteoclast recruitment. Rather, the two cell populations may derive from a common precursor or be targeted simultaneously by estrogen depletion through common stimulator(s). Mast cell hyperplasia appears to be a significant, and usually unknown, manifestation of ovariectomy in the bone marrow environment.

Contrasting effects of imidacloprid on habituation in 7- and 8-day-old honeybees (Apis mellifera).

We examined the effects of sublethal doses (0.1, 1, and 10 ng per animal) of a new neonicotinoid insecticide, Imidacloprid, on habituation of the proboscis extension reflex (PER) in honeybees (Apis mellifera) reared under laboratory conditions. In untreated honeybees, the habituation of the proboscis extension reflex is age-dependent and there is a significant increase in the number of trials required for habituation in older bees (8-10 days old) as compared to very young bees (4-7 days old). Imidacloprid alters the number of trials needed to habituate the honeybee response to multiple sucrose stimulation. In 7-day-old bees, treatment with Imidacloprid leads to an increase in the number of trials necessary to abolish the response, whereas in 8-day-old bees, it leads to a reduction in the number of trials for habituation (15 min and 1 h after treatment), and to an increase 4 h after treatment. The temporal effects of Imidacloprid in both 7- and 8-day-old bees suggest that 4h after treatment the observed effects are due to a metabolite of Imidacloprid, rather than to Imidacloprid itself. Our results suggest the existence of two distinct subtypes of nicotinic receptors in the honeybee that have different affinities to Imidacloprid and are differentially expressed in 7- and 8-day-old individuals.

Erythromelalgia and mushroom poisoning.

OBJECTIVE: To report the first European observations of erythromelalgia due to mushroom poisoning. METHODS: Clinical features of erythromelalgia were observed in 7 cases seen over 3 years. All patients had eaten the same mushrooms species, gathered in the same French alpine valley. Erythromelalgia was first described in Japan after Clitocybe acromelalga ingestion. Clitocybe amoenolens was identified as the possible cause of poisoning in our cases.

Impact of the timing of indomethacin treatment in a model of synchronized bone remodelling in rats.

Prostaglandins (PGs) promote both bone resorption and formation in vitro and in vivo. In a synchronised model of bone remodelling, indomethacin, an inhibitor of PG synthesis, given from the start of the sequence, transiently impaired bone resorption. In this study we further explored the involvement of PGs in this model by treating rats with indomethacin (7.5 mg x kg(-1) x day(-1)) for 6 days from the peak of resorption (day 4 after activation in this model) or during reversal (day 6 after activation). In rats treated from day 4, the resorption surface (Oc.S/BS) and the number of osteoclasts (N.Oc/BPm) were higher on day 10 (+69 %, P < 0.01, and +60 %, P < 0.02 compared with controls, respectively); no effect on cell resorptive activity was observed. The bone formation surface (OS/BS) was reduced (-50 %, P < 0.01). The inactive surface (In/BS) was not modified. In rats treated from day 6, the Oc.S/BS was also higher than in controls (P < 0.02), as was the N.Oc/BPm (P < 0.05). Osteoclast activity appeared to be increased, as the osteoclast-bone interface was larger (P < 0.02), but the mean lacuna area was reduced (-23 %, P < 0.05). Bone formation was also strongly affected: the OS/BS was decreased (-66 %, P < 0.01), as was the osteoid seam thickness (-24 %, P < 0.05). The In/BS was increased 1.5-fold (P < 0.05). These data indicate that PGs intervene at various stages of this remodelling sequence, as both resorption and formation were affected by indomethacin. Although resorption resumed in the two treatment groups despite treatment continuation, the timing of treatment was clearly important. Only inhibition of PG synthesis at the peak of resorption delayed all phases of the remodelling sequence. In contrast, inhibition during the reversal phase prevented activation of a significant part of the bone surface usually involved at this stage of remodelling; this treatment schedule reduced the resorptive capacity of the system, and depressed osteoblast activity.

Indapamide, a thiazide-like diuretic, decreases bone resorption in vitro.

We recently showed that indapamide (IDP), a thiazide-related diuretic, increases bone mass and decreases bone resorption in spontaneously hypertensive rats supplemented with sodium. In the present study, we evaluated the in vitro effects of this diuretic on bone cells, as well as those of hydrochlorothiazide (HCTZ), the reference thiazide, and acetazolamide (AZ), a carbonic anhydrase (CA) inhibitor. We showed that 10(-4) M IDP and 10(-4) M AZ, as well as 10(-5) M pamidronate (APD), decreased bone resorption in organ cultures and in cocultures of osteoblast-like cells and bone marrow cells in the presence of 10(-8) M 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. We investigated the mechanism of this antiresorptive effect of IDP; IDP decreased osteoclast differentiation as the number of osteoclasts developing in coculture of marrow and osteoblast-like cells was decreased markedly. We then investigated whether IDP affected osteoblast-like cells because these cells are involved in the osteoclast differentiation. Indeed, IDP increased osteoblast-like cell proliferation and alkaline phosphatase (ALP) expression. Nevertheless, it did not modify the colony-stimulating factor 1 (CSF-1) production by these cells. In addition, osteoblast-like cells expressed the Na+/Cl- cotransporter that is necessary for the renal action of thiazide diuretics, but IDP inhibited bone resorption in mice lacking this cotransporter, so the inhibition of bone resorption and osteoclast differentiation did not involve this pathway. Thus, we hypothesized that IDP may act directly on cells of the osteoclast lineage. We observed that resorption pits produced by spleen cells cultured in the presence of soluble osteoclast differentiation factor (sODF) and CSF-1 were decreased by 10(-4) M IDP as well as 10(-5) M APD. In conclusion, in vitro IDP increased osteoblast proliferation and decreased bone resorption at least in part by decreasing osteoclast differentiation via a direct effect on hematopoietic precursors.

Effects of combination of low doses of angiotensin-converting enzyme inhibitor and diuretics on renal function in spontaneously hypertensive rats: comparison between acute and chronic treatment.

The goal of this study was to assess the effect of acute or chronic treatment with S5590, a combination of the angiotensin-converting enzyme inhibitor perindopril (0.76 mg/kg/day) and the diuretic indapamide (0.24 mg/kg/day) on renal function in spontaneously hypertensive rats with moderate renal injury. Renal function was evaluated in conscious rats by clearance methods using labelled inulin and PAH, after catheterisation of the carotid artery, jugular vein and bladder. Both acute and chronic treatment normalised renal vascular resistance, although the effect on blood pressure was more marked after chronic than after acute treatment. Although acute treatment with S5590 increased glomerular filtration rate and renal blood flow, chronic treatment did not affect these parameters. Diuresis and natriuresis were only slightly modified and the results suggest a marked renal vasodilatation. In conclusion, the maintenance of renal function after chronic treatment, in a setting of normalisation of arterial pressure, suggest that such a combined treatment may exert marked renal functional protective effects in hypertension.

Osteoclasts differentiate from resident precursors in an in vivo model of synchronized resorption: a temporal and spatial study in rats.

Osteoclasts differentiate from mononucleated precursors expressing monocyte markers, which gradually evolve to preosteoclasts expressing the osteoclast phenotype. Although the role of osteogenic cells in these changes has been well documented in vitro, their contribution in vivo has not been established. In this study, a synchronized wave of resorption was activated along the mandibular periosteum. The periosteum adjacent to the bone surface studied was separated by a computer-assisted technique into an osteogenic alkaline phosphatase-positive compartment and an outer nonosteogenic compartment. Specific markers (nonspecific esterase [NSE], tartrate-resistant acid phosphatase [TRAP], and ED1 antibody, a marker of the monocyte-macrophage lineage) were used to follow osteoclast differentiation quantitatively as a function of time after activation of resorption, from day 0 to day 4 (peak of resorption in this model). Local cell proliferation was assessed in parallel. Between day 0 and day 3, the thickness of the osteogenic compartment decreased by 50% (p < 0.0002). In the osteogenic compartment, proliferating cell numbers fell by 80% at 12 day, NSE(+) cells (located farthest from the bone surface) increased 3. 9-fold on day 4 vs. day 0 (p < 0.005), ED1(+) cells decreased between day 0 and day 2 (p < 0.02) before returning to their initial value, and TRAP(+) cells increased 2.7-fold between day 1 and day 3 (p < 0.0005). Resorption was absent in the site studied on day 0, but on day 4 there were 20.5 osteoclast nuclei per millimeter of bone surface. The cell ratio changed from 30.3 NSE(+) and ED1(+) (some of which were also TRAP(+)) cells per millimeter on day 0 to 37.6 mononucleated cells plus 20.5 osteoclast nuclei on day 4. In the nonosteogenic compartment, an entry of ED1(+)/NSE(-) was observed on 12 day (+23 cells, p < 0.02 vs. day 0). This was followed by a return of ED1(+) cell numbers to the control level on day 1, and a transient increase in NSE(+) cells (+47% on day 2 vs. day 1, p < 0.02). TRAP(+) cells were never seen in this compartment. Proliferating cell numbers did not change throughout the study. Our results strongly suggest that the osteoclasts present on day 4 differentiated from the pool of TRAP(+), ED1(+), and NSE(+) cells present at the site on day 0. The osteogenic compartment was gradually replenished by cells migrating from the nonosteogenic compartment, which was supplemented by ED1(+) cells recruited from the circulation early after activation. Moreover, osteogenic cells appeared to be as crucial in vivo for the acquisition of the TRAP phenotype as previously shown in vitro.

Pharmacodynamic and pharmacokinetic profile of S 17092, a new orally active prolyl endopeptidase inhibitor, in elderly healthy volunteers. A phase I study.

AIMS: The aim of this study was to characterize the pharmacodynamics and the pharmacokinetics of S 17092, a new orally active prolyl endopeptidase inhibitor following single and repeated administration in elderly healthy volunteers. METHODS: This was a double-blind, randomized, placebo-controlled, single and multiple dose study in elderly healthy male and female volunteers (n = 36). Four doses were investigated in sequential order: 100, 400, 800 and 1200 mg. Each dose was administered orally once a day in single administration and then, after a 1 week washout period, during 7 days. Pharmacodynamics were assessed by measurement of plasmatic prolyl endopeptidase (PEP) activity, quantitative electroencephalogram (EEG) and psychometric tests. S 17092 concentrations in plasma were quantified by high performance liquid chromatography with tandem mass spectrometric detection. RESULTS: PEP activity in plasma was dose-dependently inhibited both after administration of a single dose and after repeated doses of S 17092. The mean maximal inhibition was obtained within 0.5-2 h after dosing, while inhibition lasted at least 12 h after dose administration. S 17092 appeared to be a centrally active substance as it induced statistically significant modifications in EEG compared with placebo. S 17092 at 100 mg exerted an acute increase in alpha band following single administration at 4 h and 8 h postdosing. When administered repeatedly over 7 days S 17092 did not appear to induce significant lasting central nervous system (CNS) effects. In psychometric tests, response times in the numeric working memory were significantly reduced compared with placebo, following the 800 mg dose. There were some beneficial residual effects of the 1200 mg dose on day 13: delayed word recall and word recognition sensitivity improved compared with the declines noted under placebo. Maximum measured concentration (Cmax) and area under the curve (AUC) parameters increased in proportion to the dose. The terminal half-life (t(1/2)) values ranged between 9 and 31 h on day 1 and between 7 and 18 h on day 14. A high interindividual variability was observed at all dose levels. S 17092 was well tolerated with no clinically significant changes in laboratory or physical parameters observed at any dose. CONCLUSIONS: S 17092 had a potent, dose-dependent inhibitory effect on plasmatic PEP, increased alpha band EEG at the 100 mg dose and improved performance in two verbal memory tests at the 1200 mg dose while there were disruption to the vigilance task. The results obtained in elderly healthy subjects indicated that S 17092 is suitable for once-daily dosing without any serious adverse events.

Gas vesicle genes in Planktothrix spp. from Nordic lakes: strains with weak gas vesicles possess a longer variant of gvpC.

In cyanobacteria of the genus Planktothrix:, there are three length variants of gvpC, the gene that encodes the outer protein of the gas vesicle. Sequence analyses indicated that the three allelic variants of gvpC differ principally in the presence or absence of a 99 nt and a 213 nt section. Strains with the new variant, gvpC(28), which encodes a 28 kDa form of GvpC, produce gas vesicles that collapse at the relatively low critical pressure (p(c)) of 0.61-0.75 MPa. The authors have identified 12 classes of gvp genotypes that differ in the number and arrangement of alternating gvpA-gvpC genes and in the presence of OmegaC, a fragment of gvpC. The gvpC(28) gene was found to be the most common variant of gvpC amongst 71 strains of Planktothrix: isolated from Nordic lakes: 34 strains contained only gvpC(28); 22 strains, which possessed only the shorter gvpC(20) gene, produced gas vesicles with a higher p(c) of 0.76-0.91 MPa; and 15 strains, which possessed both gvpC(20) and gvpC(28), also produced the stronger gas vesicles. Genotypes with only the gvpC(28) genes were more common amongst green Planktothrix: strains (33 out of 38) than red strains (one out of 33). It is suggested that there is competition between the strains producing the two types of gas vesicles, with the stronger forms favoured in lakes deeper than 60 m, in which the combination of cell turgor pressure and hydrostatic pressure can collapse the weaker gas vesicles. The fact that none of the Nordic lakes are deeper than 67 m would explain the absence of the gvpC(16)-containing strains that produce even narrower gas vesicles of p(c) 1.0-1.2 MPa, which are common in the much deeper Lake Zürich.