Revisiting the phylogeography and demography of European badgers (Meles meles) based on broad sampling, multiple markers and simulations.

Although the phylogeography of European mammals has been extensively investigated since the 1990s, many studies were limited in terms of sampling distribution, the number of molecular markers used and the analytical techniques employed, frequently leading to incomplete postglacial recolonisation scenarios. The broad-scale genetic structure of the European badger (Meles meles) is of interest as it may result from historic restriction to glacial refugia and/or recent anthropogenic impact. However, previous studies were based mostly on samples from western Europe, making it difficult to draw robust conclusions about the location of refugia, patterns of postglacial expansion and recent demography. In the present study, continent-wide sampling and analyses with multiple markers provided evidence for two glacial refugia (Iberia and southeast Europe) that contributed to the genetic variation observed in badgers in Europe today. Approximate Bayesian computation provided support for a colonisation of Scandinavia from both Iberian and southeastern refugia. In the whole of Europe, we observed a decline in genetic diversity with increasing latitude, suggesting that the reduced diversity in the peripheral populations resulted from a postglacial expansion processes. Although MSVAR v.1.3 also provided evidence for recent genetic bottlenecks in some of these peripheral populations, the simulations performed to estimate the method's power to correctly infer the past demography of our empirical populations suggested that the timing and severity of bottlenecks could not be established with certainty. We urge caution against trying to relate demographic declines inferred using MSVAR with particular historic or climatological events.

Characterization and role of Helix contactin-related proteins in cultured Helix pomatia neurons.

We report on the structural and functional properties of the Helix contactin-related proteins (HCRPs), a family of closely related glycoproteins previously identified in the nervous system of the land snail Helix pomatia through antibodies against the mouse F3/contactin glycoprotein. We focus on HCRP1 and HCRP2, soluble FNIII domains-containing proteins of 90 and 45 kD bearing consensus motifs for both N- and O-glycosylation. Using the anti-HCRPs serum, we find secreted HCRPs in Helix nervous tissue isotonic extracts and in culture medium conditioned by Helix ganglia. In addition, we demonstrate expression of HCRPs on neuronal soma and on neurite extensions. Functionally, in Helix neurons, the antisense HCRP2 mRNA counteracts neurite elongation, and the recombinant HCRP2 protein exerts a strong positive effect on neurite growth when used as substrate. These data point to HCRPs as novel neurite growth-promoting molecules expressed in invertebrate nervous tissue.

A novel intermediate stage in the transition between short- and long-term facilitation in the sensory to motor neuron synapse of aplysia.

A major difference between short- and long-term memory is that long-term memory is dependent on new protein synthesis. Long-term memory can be further subdivided into a transient, initial phase that is readily susceptible to disruption and a later, more stable and persistent stage. To analyze this transition on the cellular level, we have examined the steps whereby short-term facilitation is converted to a long-term form in the sensorimotor connection of the Aplysia gill-withdrawal reflex. We found that stable long-term facilitation (at 24 hr) requires a higher concentration (100 nM) of serotonin (5-HT) than does short-term facilitation (10 nM). By using low concentrations of 5-HT, which do not produce long-term facilitation, we now have been able to explore the intermediate phases between the short- and long-term processes. By this means we have uncovered a new transient phase that involves three mechanistically different mechanisms--covalent modification, translation, and transcription--each of which can be recruited as a function of the concentration of 5-HT.

Roles of PKA and PKC in facilitation of evoked and spontaneous transmitter release at depressed and nondepressed synapses in Aplysia sensory neurons.

Two second messenger pathways, one that uses the cAMP-dependent protein kinase A (PKA), the other that uses protein kinase C (PKC), have been found to contribute to the short-term presynaptic facilitation of the connections between the sensory neurons in Aplysia and their target cells, the interneurons and motor neurons of the gill-withdrawal reflex. To study their relative contributions as a function of the previous history of the neuron's activity, we have examined the effects of inhibiting PKA (using Rp-cAMPS) and PKC (using H7) on the short-term facilitation of spontaneous release as well as of the evoked release induced by serotonin at nondepressed, partially depressed, and highly depressed synapses. Our results suggest that whereas activation of PKA is sufficient to trigger the facilitation of nondepressed synapses, activation of both PKA and PKC is required to facilitate depressed synapses, with the contribution of PKC becoming progressively more important as synaptic transmission becomes more depressed.

The dependence of algal H2 production on Photosystem II and O2 consumption activities in sulfur-deprived Chlamydomonas reinhardtii cells.

Chlamydomonas reinhardtii cultures, deprived of inorganic sulfur, undergo dramatic changes during adaptation to the nutrient stress [Biotechnol. Bioeng. 78 (2002) 731]. When the capacity for Photosystem II (PSII) O(2) evolution decreases below that of respiration, the culture becomes anaerobic [Plant Physiol. 122 (2000) 127]. We demonstrate that (a) the photochemical activity of PSII, monitored by in situ fluorescence, also decreases slowly during the aerobic period; (b) at the exact time of anaerobiosis, the remaining PSII activity is rapidly down regulated; and (c) electron transfer from PSII to PSI abruptly decreases at that point. Shortly thereafter, the PSII photochemical activity is partially restored, and H(2) production starts. Hydrogen production, which lasts for 3-4 days, is catalyzed by an anaerobically induced, reversible hydrogenase. While most of the reductants used directly for H(2) gas photoproduction come from water, the remaining electrons must come from endogenous substrate degradation through the NAD(P)H plastoquinone (PQ) oxido-reductase pathway. We propose that the induced hydrogenase activity provides a sink for electrons in the absence of other alternative pathways, and its operation allows the partial oxidation of intermediate photosynthetic carriers, including the PQ pool, between PSII and PSI. We conclude that the reduced state of this pool, which controls PSII photochemical activity, is one of the main factors regulating H(2) production under sulfur-deprived conditions. Residual O(2) evolved under these conditions is probably consumed mostly by the aerobic oxidation of storage products linked to mitochondrial respiratory processes involving both the cytochrome oxidase and the alternative oxidase. These functions maintain the intracellular anaerobic conditions required to keep the hydrogenase enzyme in the active, induced form.

In vitro formation and activity-dependent plasticity of synapses between Helix neurons involved in the neural control of feeding and withdrawal behaviors.

Short-term activity-dependent synaptic plasticity has a fundamental role in short-term memory and information processing in the nervous system. Although the neuronal circuitry controlling different behaviors of land snails of the genus Helix has been characterized in some detail, little is known about the activity-dependent plasticity of synapses between identified neurons regulating specific behavioral acts. In order to study homosynaptic activity-dependent plasticity of behaviorally relevant Helix synapses independently of heterosynaptic influences, we sought to reconstruct them in cell culture. To this aim, we first investigated in culture the factors regulating synapse formation between Helix neurons, and then we studied the short-term plasticity of in vitro-reconstructed monosynaptic connections involved in the neural control of salivary secretion and whole-body withdrawal. We found that independently of extrinsic factors, cell-cell interactions are seemingly sufficient to trigger the formation of electrical and chemical synapses, although mostly inappropriate--in their type or association--with respect to the in vivo synaptic connectivity. The presence of ganglia-derived factors in the culture medium was required for the in vitro reestablishment of the appropriate in vivo-like connectivity, by reducing the occurrence of electrical connections and promoting the formation of chemical excitatory synapses, while apparently not influencing the formation of inhibitory connections. These heat-labile factors modulated electrical and chemical synaptogenesis through distinct protein tyrosine kinase signal transduction pathways. Taking advantage of in vitro-reconstructed synapses, we have found that feeding interneuron-efferent neuron synapses and mechanosensory neuron-withdrawal interneuron synapses display multiple forms of short-term enhancement-like facilitation, augmentation and posttetanic potentiation as well as homosynaptic depression. These forms of plasticity are thought to be relevant in the regulation of Helix feeding and withdrawal behaviors by inducing dramatic activity-dependent changes in the strength of input and output synapses of high-order interneurons with a crucial role in the control of Helix behavioral hierarchy.

Multielectrode arrays with elastomeric microstructured overlays for extracellular recordings from patterned neurons.

Multielectrode array technology constitutes a promising approach for the characterization of the activity-dependent neuronal plasticity underlying information processing in the nervous system. For this purpose, long-term monitoring and stimulation of cultured neuronal networks with one-to-one neuron-sensor interfacing is advantageous. Existing neurochips that meet these specifications have made use of custom 3D structures requiring clean-room intensive microfabrication techniques. Low-cost fabrication procedures with potential for mass production would facilitate progress in the area. To this end, we have developed a sandwich structure comprising an elastomeric film, microstructured by replica moulding and microhole punching, for neuronal patterning, and a standard planar microelectrode array (MEA), for stimulation and recording. The elastomeric film includes microwells for cell body confinement, and microchannels capable of guiding neurites for network topology specification. The device is formed by overlaying the elastomeric structures on planar arrays. The combination of replica moulding, rapid prototyping and planar MEAs results in low-cost neurochips accessible to most neurophysiology labs. Single neuron patterning and recordings of extracellular potentials are demonstrated.

[Photochemical activity of photosystem II and hydrogen photoproduction in sulfur-deprived Chlamydomonas reinhardtii mutants D1-R323D and D1-R323L].

The role of photosystem II in hydrogen photoproduction by Chlamydomonas reinhardtii cells was studied in mutants with modified D1-protein. In D1-R323D and D1-R323L mutants, the replacement of arginine by aspartate or leucine, respectively, resulted in the disruption of electron transport at the donor side of photosystem II. The rate of oxygen evolution in D1-R323D decreased twice as compared to the pseudo-wild type (pWT), and in D1-R323L no oxygen evolution was detected. The latter mutant was not capable of photoautotrophical growth. The dynamics of changes in oxygen content, the reduction of photosystem II active reaction centers (deltaF/F(1)m), and hydrogen production rate in pWT were found to be similar to the wild type if cultivated under sulfur deprivation in a closed bioreactor. The observed gradual decrease in the deltaF/F(1)m value turned to a sharp drop almost to zero followed by a partial recovery during which the production of hydrogen set in. The transition to the anaerobic phase in D1-R323D cultured in a sulfur-deprived medium occurred earlier than it happened in pWt under the same conditions. However, the partial recovery of photosystem II activity and hydrogen production started at a later time, and the rate of hydrogen production was low. The D1-R323L mutant incapable of oxygen evolution entered the rapidly anaerobiosis but produced no hydrogen. The kinetics of photoinduced redox transitions in P700 was similar in all investigated strains and was not affected by diuron addition. This implies that the mutants had a pool of reducers, which could donate electrons through the quinone pool or cytochrome to photosystem I. However, in D1-R323L mutant lacking the active photosystem II, this condition was not sufficient to support hydrogenase activity.

Knock-down of synapsin alters cell excitability and action potential waveform by potentiating BK and voltage-gated Ca(2+) currents in Helix serotonergic neurons.

Synapsins (Syns) are an evolutionarily conserved family of presynaptic proteins crucial for the fine-tuning of synaptic function. A large amount of experimental evidences has shown that Syns are involved in the development of epileptic phenotypes and several mutations in Syn genes have been associated with epilepsy in humans and animal models. Syn mutations induce alterations in circuitry and neurotransmitter release, differentially affecting excitatory and inhibitory synapses, thus causing an excitation/inhibition imbalance in network excitability toward hyperexcitability that may be a determinant with regard to the development of epilepsy. Another approach to investigate epileptogenic mechanisms is to understand how silencing Syn affects the cellular behavior of single neurons and is associated with the hyperexcitable phenotypes observed in epilepsy. Here, we examined the functional effects of antisense-RNA inhibition of Syn expression on individually identified and isolated serotonergic cells of the Helix land snail. We found that Helix synapsin silencing increases cell excitability characterized by a slightly depolarized resting membrane potential, decreases the rheobase, reduces the threshold for action potential (AP) firing and increases the mean and instantaneous firing rates, with respect to control cells. The observed increase of Ca(2+) and BK currents in Syn-silenced cells seems to be related to changes in the shape of the AP waveform. These currents sustain the faster spiking in Syn-deficient cells by increasing the after hyperpolarization and limiting the Na(+) and Ca(2+) channel inactivation during repetitive firing. This in turn speeds up the depolarization phase by reaching the AP threshold faster. Our results provide evidence that Syn silencing increases intrinsic cell excitability associated with increased Ca(2+) and Ca(2+)-dependent BK currents in the absence of excitatory or inhibitory inputs.

Microalgae: a green source of renewable H(2).

This article summarizes recent advances in the field of algal hydrogen production. Two fundamental approaches are being developed. One involves the temporal separation of the usually incompatible reactions of O(2) and H(2) production in green algae, and the second involves the use of classical genetics to increase the O(2) tolerance of the reversible hydrogenase enzyme. The economic and environmental impact of a renewable source of H(2) are also discussed.

Spontaneous Saccades and Gaze-Holding Ability in the Pigmented Rat. I. Effects of Inferior Olive Lesion.

We have studied the effects of lesion of the inferior olive on the spontaneous eye movements performed both in the light and dark in head restrained pigmented rats. The inferior olive lesion was made at least 1 month before study with 3-acetylpyridine and eye movements were recorded through a phase detection search coil apparatus. Following lesion, the spontaneous saccades performed in the dark present a postsaccadic drift which is made up of two components characterized by their different time courses, the first one being fast and the second one slow. The latter component is due to the leakage of the neural integrator and the former is mainly the consequence of a mismatch between the phasic and the tonic component of the ocular movement. In the light only the first component is present and then the eye maintains a steady position. After the lesion the saccades in the dark present a time constant of the slow component of the postsaccadic drift which is significantly reduced to approximately 600 - 900 ms from a value of 1600 - 4000 ms of the intact rats. This means that the integrity of the inferior olive is necessary to keep the time constant of the neural integrator within the physiological range. In the light, the amplitude of the postsaccadic drift depends on two factors. First, there is a mismatch between the phasic and the tonic components of the ocular movement, which are due to the pulse and the step of innervation of the extraocular muscles respectively. Different types of analysis have shown that the gain of the pulse to step transformation is about 0.77 at all saccadic amplitudes and eccentricities. Second, there is an increased leakiness of the neural integrator. Such a contribution increases linearly as a function of the eccentricity with a slope of 0.21. The main sequence of the saccades is not appreciably affected by the olivary lesion. Thus, the consequence of the inferior olive lesion may be interpreted as a general disruption of the integration process which, in physiological conditions, generates a proper and sustained oculomotor signal. More generally, it may be viewed as a loss of coordination between phasic and tonic motor commands.

Spontaneous Saccades and Gaze-Holding Ability in the Pigmented Rat. II. Effects of Localized Cerebellar Lesions.

We have studied the effects of the ablation of the cerebellar vermal area corresponding to lobules VI - VIII and of the flocculus - paraflocculus of both sides on the spontaneous eye movements performed in the light and in the dark in head-restrained pigmented rats. These effects have been compared with those already described for the inferior olive lesion. The cerebellar lesions were performed 1 week to 6 months in advance. Eye movements were recorded through a phase detection search coil apparatus. Following vermal topectomy, the main characteristics of the spontaneous saccades are unmodified. Following the ablation of the flocculus - paraflocculus there is no change in the saccadic main sequence. However, the spontaneous saccades in the dark present a postsaccadic drift made up of two components with different time courses, the first one being fast and the second one slow. The former is due in part to a mismatch between the phasic (the pulse) and the tonic (the step) components of the eye movements; the latter to the leakage of the neural integrator. In light only the first component is present and the eye maintains a steady position. The time constant of the neural integrator is considerably reduced to approximately 600 - 900 ms from a value of approximately 1600 - 4000 ms in the intact rats. The amplitude of the postsaccadic drift in the light depends on both the mismatch between the pulse and the step of innervation of the extraocular muscles and the increased leakiness of the neural integrator. The gain of the pulse to step transformation is reduced to approximately 0.79 at all saccadic amplitudes and eccentricities and such a reduction is due to a decreased step amplitude, while the pulse amplitude remains unchanged. The contribution of the leakage of the neural integrator to the postsaccadic drift in the light is a function of the eccentricity with a slope of 0.23. The deficits described after flocculus - paraflocculus ablation are also very similar to those described following inferior olive lesion from a quantitative point of view. The possible mechanisms of the visually activated olivocerebellar system in the control of saccadic performance and in maintaining its calibration are discussed.

Saccadic Eye Movements and Gaze Holding in the Head-Restrained Pigmented Rat.

Spontaneous saccadic eye movements were recorded in seven head-restrained pigmented rats by means of a phase detection search coil system, both in the light and in the dark. In an illuminated environment, all the rats made numerous spontaneous saccades with an average amplitude of 13.2 deg (+/- 2.2 SD) and a maximal amplitude of 35 deg. In the dark, mean saccadic amplitude was significantly reduced to 9.2 deg (+/- 2.0 SD). Saccadic peak velocity increased linearly as a function of saccadic size, with no saturation at high amplitude values. In the light, peak velocity increase was 32.7 deg/s/deg (+/- 3.5 SD). This value is higher than that described in many other species including man and is similar to that of the monkey. Also saccadic duration increased linearly as a function of size at a rate of 1 ms/deg, which is closer to that of monkey than to that of other species including man. Both peak velocity and duration were not significantly different in the dark from those measured in the light. In the light, following a saccadic gaze shift, the rats were able to maintain a steady eye position for long periods, also at large orbital eccentricities. In the dark, on the contrary, the eye presented a drift towards the central position in the orbit. Such a drift had an exponential-like time course with a time constant of 1567 ms (+/- 829 SD), a value which is much shorter than that of cat and primates. This indicates that in the absence of a visual input, the rat has a poor gaze holding ability compared to other species.

Aberrant crypt foci in the human colon: frequency and histologic patterns in patients with colorectal cancer or diverticular disease.

Aberrant crypt foci are considered potential markers of colorectal cancer risk. The aim of this study was to analyze a large series of human aberrant crypt foci according to frequency, distribution, and histology. Aberrant crypt foci were identified in methylene blue-stained colonic mucosa from 103 patients undergoing surgery for colorectal cancer or diverticular disease. Foci were histologically classified into surface hyperplastic type, surface and glandular hyperplastic type, mixed hyperplastic and adenomatous type, and adenomatous type. The mean frequency of aberrant crypt foci (n = 720) was higher in the colorectal cancer group (0.20/cm2) than in the diverticular disease group (0.07/cm2), and in distal colonic segments than in proximal segments. Most of the histologically examined foci (n = 366) were hyperplastic (88.8%). Surface hyperplasia accounted for 30.6% and prevailed in small lesions. Surface and glandular hyperplasia accounted for 58.2% and prevailed in medium-sized to large foci. Partially or totally dysplastic foci accounted for 10.1% of examined lesions (10.8% and 2.8% in the colorectal cancer and diverticular disease groups, respectively). Most of them (94.6%) were composed of mixed hyperplastic and adenomatous crypts and prevailed in large lesions. The higher frequency of aberrant crypt foci in patients with colorectal cancer sustains their putative role as preneoplastic markers. The high rate of mixed hyperplastic and adenomatous lesions supports the possible adenomatous transformation of hyperplastic lesions.

Intracellular injection of synapsin I induces neurotransmitter release in C1 neurons of Helix pomatia contacting a wrong target.

The contact with the postsynaptic target induces structural and functional modifications in the serotonergic cell C1 of Helix pomatia. In previous studies we have found that the presence of a non-physiological target down-regulates the number of presynaptic varicosities formed by cultured C1 neurons and has a strong inhibitory effect on the action potential-evoked Ca(2+) influx and neurotransmitter release at C1 terminals. Since a large body of experimental evidence implicates the synapsins in the development and functional maturation of synaptic connections, we have investigated whether the injection of exogenous synapsin I into the presynaptic neuron C1 could affect the inhibitory effect of the wrong target on neurotransmitter release. C1 neurons were cultured with the wrong target neuron C3 for three to five days and then injected with either dephosphorylated or Ca(2+)/calmodulin-dependent protein kinase II-phosphorylated Cy3-labeled synapsin I. The subcellular distribution of exogenous synapsin I, followed by fluorescence videomicroscopy, revealed that only synapsin I phosphorylated by Ca(2+)/calmodulin-dependent protein kinase II diffused in the cytoplasm and reached the terminal arborizations of the axon, while the dephosphorylated form did not diffuse beyond the cell body. Evoked neurotransmitter release was measured during C1 stimulation using a freshly dissociated neuron B2 (sniffer) micromanipulated in close contact with the terminals of C1. A three-fold increase in the amplitude of the sniffer depolarization with respect to the pre-injection amplitude (190+/-29% increase, n=10, P<0.006) was found 5 min after injection of Ca(2+)/calmodulin-dependent protein kinase II-phosphorylated synapsin I that lasted for about 30 min. No significant change was observed after injection of buffer or dephosphorylated synapsin I. These data indicate that the presence of synapsin I induces a fast increase in neurotransmitter release that overcomes the inhibitory effect of the non-physiological target and suggest that the expression of synapsins may play a role in the modulation of synaptic strength and neural connectivity.

Influence of the target on distribution and functioning of the varicosities of Helix pomatia metacerebral cell C1 in dissociated cell culture.

The serotonergic metacerebral giant cell (C1) of Helix pomatia was isolated with its bifurcate axon and plated in culture under five conditions: (i) with no target; (ii) with the appropriate target B2 near the stump of the bigger branch (CBC); (iii) with B2 near the stump of the smaller branch (CC); (iv) with a wrong target (C3) near the stump of the CBC branch and (v) with B2 and C3 positioned near the CBC and CC stump, respectively. The counting of anti-serotonin antibody-labelled varicosities of the C1 neuron showed that the presence of the appropriate target in either axonal domain both down-regulated the number of varicosities of the contralateral neuritic field, and increased their average size, whereas the wrong target induced an overall reduction of the number of C1 neuron varicosities, and inhibited the evoked transmitter release. The action potential-evoked calcium concentration increase in the neuritic terminals of the C1 neuron cultured alone, or in presence of the appropriate target, reached a value significantly higher than that reached in presence of the wrong target. These results provide evidence that the postsynaptic neuron regulates both morphological and functional development of presynaptic terminals.

Aplysia hemolymph promotes neurite outgrowth and synaptogenesis of identified Helix neurons in cell culture.

Hemolymph of adult Aplysia californica significantly affects neurite outgrowth of identified neurons of the land snail Helix pomatia. The metacerebral giant cell (MGC) and the motoneuron C3 from the cerebral ganglion and the neuron B2 from the buccal ganglion of H. pomatia were isolated by enzymatic and mechanical dissociation and plated onto poly-L-lysine-coated dishes either containing culture medium conditioned by Helix ganglia, or pre-treated with Aplysia hemolymph. To determine the extent of neuronal growth we measured the neurite elongation and the neuritic field of cultured neurons at different time points. Aplysia hemolymph enhances the extent and rate of linear outgrowth and the branching domain of Helix neurons. With the hemolymph treatment the MGC neuron more consistently forms specific chemical synapses with its follower cell B2, and these connections are more effective than those established in the presence of the conditioned medium.

Oxygen sensitivity of algal H2- production.

Photoproduction of H2 by green algae utilizes electrons originating from the photosynthetic oxidation of water and does not require metabolic intermediates. However, algal hydrogenases are extremely sensitive to O(2), which limits their usefulness in future commercial H2-production systems. We designed an experimental technique for the selection of O2-tolerant, H2-producing variants of Chlamydomonas reinhardtii based on the ability of wild-type cells to survive a short (20 min) exposure to metronidazole in the presence of controlled concentrations of O2. The number of survivors depends on the metronidazole concentration, light intensity, preinduction of the hydrogenase, and the presence or absence of O2. Finally, we demonstrate that some of the selected survivors in fact exhibit H2-production capacity that is less sensitive to O2 than the original wild-type population.

[Non-polyposis colorectal cancer in subjects under 55 years of age: frequency and phenotype of hereditary or familial syndromes]. / Il cancro non polipotico del colon e del retto sotto i 55 anni di età: frequenza e fenotipo delle sindromi a predisposizione ereditaria o familiare.

Young age is believed to be a risk factor for hereditary or familial non-polyposis colorectal cancer. Present study analysed frequency, phenotype and familial cancer risk of 82 subjects with colorectal cancer under 55 years of age. According to age and family history, probands have been subdivided into 5 groups: Hereditary Non-Polyposis Colorectal Cancer (HNPCC) (8.2% of cases); Suspected HNPCC (7.3%); Non-specific familial aggregation of colorectal cancer (AFACC) (19.5%); Early-onset colorectal cancer (diagnosis under 35 years of age) (CCG) (6.1%); Sporadic colorectal cancer (CCS) (58.5%). Proportions of probands with multiple colonic tumours were highest in HNPCC (57.1%), but present in AFACC (12.5%) and CCG (20.0%) groups, as well. Extracolonic, in particular endometrial and ovarian cancers have been found in HNPCC and AFACC probands. Tumours of proximal colon were most frequent in HNPCC, suspected HNPCC, CCG patients. Eleven-years survival rate was higher in HNPCC probands then in CCS group. Familial cancer risk in HNPCC was 3 times as much as in CCG + CCS groups. Diagnosis of colorectal cancer under 55 years of age is associated with an high frequency of hereditary or familial cases. Genetic tests, surveillance and screening programs in these patients must be based on extensive phenotype and pedigree analyses. HNPCC is widely represented in young colorectal cancer patients and is associated with a high risk of multiple synchronous or metacronous colonic and extracolonic tumours. Total colectomy and eventual hysterectomy with bilateral oophorectomy seem therefore recommendable options in these patients.

Distribution of 1,2 DMH-induced colonic aberrant crypt foci after administration of a gastrin receptor antagonist (CR2945), in the murine model.

Our previous experimental data demonstrated that a new gastrin receptor antagonist (CR2945) has a chemopreventive effect on dimethylhydrazine-induced colon cancer in mice. The aim of this study is to test the effect of CR2945 on the appearance and distribution of aberrant crypt foci (ACF), proposed as early "preneoplastic" lesions in colon carcinogenesis, in the murine model. 176 CD1 male mice were randomly divided into 4 groups: group 1, sham group received 2 daily intra-peritoneal injections of saline solution; group 2 received 1 weekly intra-peritoneal injection of DMH 20 mg/kg, for 5 weeks, and 2 daily intra-peritoneal injections of equal volume of NaCl 0.9%; group 3 and 4 received the same weekly dose of DMH and 2 daily injections of CR2945 at the respective doses of 2.5 and 7.5 mg/Kg for 5 weeks. The rodents were sacrified 15, 20, 25, and 38 weeks after receiving the first injection. The number of ACF per area (ACF frequency), their multiplicity (number of crypts per focus), ACF frequency according to each colonic site were recorded. No ACF were found in the sham group. No substantial differences were observed in ACF distribution between the remaining groups. Our hypothesis is that CR2945 does not alter the final number of ACF but might induce a regression of some dysplastic ACF.