Multidetector CT and virtual endoscopy in the evaluation of the esophagus

In this prospective study, we assessed the diagnostic capabilities of multidetector computed tomography (CT) in various esophageal pathologic conditions. Thirty-three patients underwent a multidetector CT study after esophageal distention by means of effervescent powder administered after induction of pharmacologic esophageal hypotonia. All acquired images were post-processed with two- and three-dimensional software tools. The CT data were compared with the results of conventional radiology (33), endoscopy (28), endoscopy ultrasonography (14), or surgery (14). Follow-up ranged between 4 and 15 months. Esophageal distention in the upper and middle thirds was classified as "good" in 32 of 33 cases (97%); in the lower third, esophageal distention was "good" in 21 of 33 cases (64%). Final diagnoses were leiomyoma (six cases), squamous cell carcinoma (six), adenocarcinoma (four), esophageal infiltration by thyroid cancer (two), benign polyposis (two), chronic esophagitis (five), post-sclerotherapy stenosis (one), no abnormalities (seven). When good distention was achieved, the thickness of unaffected esophageal wall was less than 3 mm (range, 1.5-2.4 mm; mean, 1.9 mm). Pathologic wall thickening was observed in 25 of 33 cases (76%), with values ranging between 3.6 and 36 mm (mean, 9.6 mm). Spiral CT demonstrated 21 true positive cases, and seven true negative cases. There were four false negative cases and one false positive case. Sensitivity was 84%, specificity was 87%, diagnostic accuracy was 85%, positive predictive value was 95%, and negative predictive value was 64%. Evaluation of the esophagus with multidetector CT is a promising technique and easy to use, allowing panoramic exploration, virtual endoluminal visualization, accurate longitudinal and axial evaluations, and simultaneous evaluation of T and N parameters.

Bone mass evaluated by calcaneous ultrasound and radial peripheral computed tomography in 726 youngsters

AIM

To compare the results of ultrasound and computed peripheral tomography in evaluating bone mass in a population of normal children.

METHODS

Seven hundred and twenty-six healthy school children (260 males; age 8.3-20.9 y) underwent calcaneous ultrasound and peripheral computed tomography at the ultradistal radius. Broadband ultrasound attenuation (BUA) and areal and volumetric bone mineral density (aBMD and vBMD) were evaluated. The results were compared and correlated among them and with auxological parameters (height, BMI and pubertal stages) using the software package SPSS for Windows.

RESULTS

The three variables examined (BUA, aBMD and vBMD) all showed a progressive increase with age and a positive correlation with age, height and BMI. When the population was subdivided according to pubertal stages, all variables showed a progressive increase, the difference being significant when stages 1-2 were compared with stages 4-5. A significant correlation was present among BUA, aBMD and vBMD even if the Pearson correlation coefficient was not high.

CONCLUSIONS

The similar pattern of BUA, aBMD and vBMD with respect to age, height and pubertal stages indicates that ultrasound could be a reliable method to screen bone mass abnormalities in children. The low correlation coefficient, however, suggests that the methods employed measure different bone parameters. Moreover, the different skeletal locations could also account for these results.

The different apoptotic potential of the p53 codon 72 alleles increases with age and modulates in vivo ischaemia-induced cell death

A common arginine to proline polymorphism is harboured at codon 72 of the human p53 gene. In this investigation, we found that fibroblasts and lymphocytes isolated from arginine allele homozygote centenarians and sexagenarians (Arg+) undergo an oxidative-stress-induced apoptosis at a higher extent than cells obtained from proline allele carriers (Pro+). At variance, the difference in apoptosis susceptibility between Arg+ and Pro+ is not significant when cells from 30-year-old people are studied. Further, we found that Arg+ and Pro+ cells from centenarians differ in the constitutive levels of p53 protein and p53/MDM2 complex, as well as in the levels of oxidative stress-induced p53/Bcl-xL complex and mitochondria-localised p53. Consistently, all these differences are less evident in cells from 30-year-old people. Finally, we investigated the in vivo functional relevance of the p53 codon 72 genotype in a group of old patients (66-99 years of age) affected by acute myocardial ischaemia, a clinical condition in which in vivo cell death occurs. We found that Arg+ patients show increased levels of Troponin I and CK-MB, two serum markers that correlate with the extent of the ischaemic damage in comparison to Pro+ patients. In conclusion, these data suggest that p53 codon 72 polymorphism contributes to a genetically determined variability in apoptotic susceptibility among old people, which has a potentially relevant role in the context of an age-related pathologic condition, such as myocardial ischaemia.

The nematode-resistance gene, Mi-1, is associated with an inverted chromosomal segment in susceptible compared to resistant tomato

The gene Mi-1 confers effective resistance in tomato ( Lycopersicon esculentum) against root-knot nematodes and some isolates of potato aphid. This locus was introgressed from L. peruvianum into the corresponding region on chromosome 6 in tomato. In nematode-resistant tomato, Mi-1 and six homologs are grouped into two clusters separated by 300 kb. Analysis of BAC clones revealed that the Mi-1 locus from susceptible tomato carried the same number and distribution of Mi-1 homologs, as did the resistant locus. Molecular markers flanking the resistant and susceptible loci were in the same relative orientation, but markers between the two clusters were in an inverse orientation. The simplest explanation for these observations is that there is an inversion between the two clusters of homologs when comparing the Mi-1 loci from L. esculentum and L. peruvianum. Such an inversion may explain previous observations of severe recombination suppression in the region. Two Mi-1 homologs identified from the BAC library derived from susceptible tomato are not linked to the chromosome 6 locus, but map to chromosome 5 in regions known to contain resistance gene loci in other solanaceous species.

Solution Structure and Backbone Dynamics of the K18G/R82E Alicyclobacillus acidocaldarius Thioredoxin Mutant: A Molecular Analysis of Its Reduced Thermal Stability,

No general strategy for thermostability has been yet established, because the extra stability of thermophiles appears to be the sum of different cumulative stabilizing interactions. In addition, the increase of conformational rigidity observed in many thermophilic proteins, which in some cases disappears when mesophilic and thermophilic proteins are compared at their respective physiological temperatures, suggests that evolutionary adaptation tends to maintain corresponding states with respect to conformational flexibility. In this study, we accomplished a structural analysis of the K18G/R82E Alicyclobacillus acidocaldarius thioredoxin (BacTrx) mutant, which has reduced heat resistance with respect to the thermostable wild-type. Furthermore, we have also achieved a detailed study, carried out at 25, 45, and 65 degrees C, of the backbone dynamics of both the BacTrx and its K18G/R82E mutant. Our findings clearly indicate that the insertion of the two mutations causes a loss of energetically favorable long-range interactions and renders the secondary structure elements of the double mutants more similar to those of the mesophilic Escherichia coli thioredoxin. Moreover, protein dynamics analysis shows that at room temperature the BacTrx, as well as the double mutant, are globally as rigid as the mesophilic thioredoxins; differently, at 65 degrees C, which is in the optimal growth temperature range of A. acidocaldarius, the wild-type retains its rigidity while the double mutant is characterized by a large increase of the amplitude of the internal motions. Finally, our research interestingly shows that fast motions on the pico- to nanosecond time scale are not detrimental to protein stability and provide an entropic stabilization of the native state. This study further confirms that protein thermostability is reached through diverse stabilizing interactions, which have the key role to maintain the structural folding stable and functional at the working temperature.

Structural Studies of the β-Glycosidase from Sulfolobus solfataricus in Complex with Covalently and Noncovalently Bound Inhibitors

Transition-state mimicry is increasingly important both to understand enzyme mechanism and to direct the synthesis of putative therapeutic agents. X-ray crystallography is able to provide vital information on the interactions between an enzyme and the potential inhibitor. Here we report the structures, at approximately 2 A resolution, of a family GH1 beta-glycosidase from the hyperthermophilic archaeon Sulfolobus solfataricus, in complex with both covalently (derived from 2-fluoro-glycosides) and noncovalently (hydroximolactam) bound inhibitors. The enzyme has broad specificity, accommodating both gluco- and galacto-configured substrates, and the crystallographic data demonstrate that the only difference in the way these ligands bind lies in the interactions between Gln18, Glu432, and Trp433, and the hydroxyl group at the O3 and O4 positions. Inhibition by the differently configured ligands was also shown to be extremely similar, with K(i) values of 1.04 and 1.08 microM for the gluco and galacto epimers, respectively. The noncovalently bound inhibitors have a trigonal anomeric carbon, adopt a (4)H(3) (half-chair) conformation, and an interaction is formed between O2 and the catalytic nucleophile, all of which contribute to (partial) mimicry of the oxocarbenium-ion-like transition state. The inhibition of the beta-glycosidase from S. solfataricus by hydroximolactams is discussed in light of the emerging work on family GH1 glycosidase inhibition by a spectrum of putative transition-state mimics.

Crystal structure of a ternary complex of the alcohol dehydrogenase from Sulfolobus solfataricus

The crystal structure of a ternary complex of the alcohol dehydrogenase from the archaeon Sulfolobus solfataricus (SsADH) has been determined at 2.3 A. The asymmetric unit contains a dimer with a NADH and a 2-ethoxyethanol molecule bound to each subunit. The comparison with the apo structure of the enzyme reveals that this medium chain ADH undergoes a substantial conformational change in the apo-holo transition, accompanied by loop movements at the domain interface. The extent of domain closure is similar to that observed for the classical horse liver ADH, although some differences are found which can be related to the different oligomeric states of the enzymes. Compared to its apo form, the SsADH ternary complex shows a change in the ligation state of the active site zinc ion which is no longer bound to Glu69, providing additional evidence of the dynamic role played by the conserved glutamate residue in ADHs. In addition, the structure presented here allows the identification of the substrate site and hence of the residues that are important in the binding of both the substrate and the coenzyme.

Survival in kidney transplantation from living donors: a single-center experience

BACKGROUND

Transplantation from living donors, in Italy, is still not accepted, in particular those from unrelated donors. The aim of this paper was to present the experience of one transplant center.

MATERIALS AND METHODS

Since 1982, 608 transplants were performed from living donors using cyclosporine as the main component of immunosuppressive therapy. Among those, 402 transplants were from related living donors (338 one haplotype pairs and 25 zero haplotypes pairs) and 206 from unrelated living donors (171 spouses and 35 emotionally related subjects).

RESULTS

Graft survival at 1, 5, and 10 years showed no statistically meaningful difference between the two groups. A group of 19 transplants performed in predialytic phase patients was compared with a contemporaneous group of 167 transplants performed in patients who were already receiving dialysis. These two groups did not show any statistically meaningful difference in graft survival at 1, 5, or 10 years.

DISCUSSION AND CONCLUSIONS

We think that transplants from living donors, whether related or unrelated, must always be proposed as a therapeutic option for end-stage renal disease patients, since they show an higher graft survival than that from cadaveric donors, independent of the compatibility between donor and recipient and independent of the degree of relationship of the pair. Transplantation from living donors definitely is a complementary, not substitutive, program to that from cadaveric donors, which should always be encouraged with awareness campaigns among the population and targeted programs for healthy personnel.

Competitive Season of Triathlon Does not Alter Bone Metabolism and Bone Mineral Status in Male Triathletes

This longitudinal study evaluated the effects of a triathlon season on bone metabolism and hormonal status. Seven male competitive triathletes (mean age 19.3 years, range 18 - 20) with 5.0 +/- 0.3 years of competition experience were tested twice during the season: at the beginning of training and 32 weeks later. Total and regional bone mineral density (BMD) was determined by dual-energy X-ray absorptiometry, while bone turnover was evaluated by specific biochemical markers: bone-specific alkaline phosphatase (B-ALP), osteocalcin, and urinary type I collagen C-telopeptide. In addition, sexual, calciotropic and somatotropic hormones were also analyzed. After 32 weeks, a BMD increase was found at the lumbar spine (1.9 %; p = 0.031) and skull (3.1 %; p = 0.048), while no variation was observed for total body or at the proximal femur. The B-ALP level decreased (-23.2 %; p = 0.031), but no variation was found for the other bone markers. 1.25 (OH) (2)D3, IGF-1 and the bioavailability IGF-1 index (IGF-1/IGFBP-3) increased by 18.3 % (p = 0.047), 29 % (p = 0.048), 33 % (p = 0.011), respectively, while PTH, testosterone, IGFBP-3 and cortisol concentrations were unchanged. In conclusion, the triathlon season had a moderately favourable effect on BMD, although a slowing down of bone formation activity was observed. No variation in hormonal levels was observed that could have limited the effects of exercise on bone tissue.

A nonuniformly stretched vortex

A stretched vortex model is proposed which includes a nonuniform stretching in the radial direction that is clearly present in real flows, as well as a slow variation of velocity profiles along the vortex axis. Both features of this boundary layer approximation depart from the classical Burgers solution. This model is shown to be in very good agreement with experimental velocity measurements.

A xylan-degrading strain of Sulfolobus solfataricus: isolation and characterization of the xylanase activity

Two strains (O(alpha) and X(2)) of the hyperthermophilic crenarchaeon Sulfolobus solfataricus strain MT4 were selected and isolated for their ability to grow on xylan. O(alpha) and X(2), grown on media containing oat spelt xylan and birchwood xylan as the sole nutrient source, respectively, produced the same thermostable xylanase that was demonstrated to be inducible in xylan cultures. In an oat spelt medium, S. solfataricus O(alpha) underwent interesting morphological changes in the cell envelope, exhibiting mobile appendages not present in the typical coccal shape. The enzyme was prevalently membrane associated and showed a molecular mass of approximately 57.0 kDa. It was also highly thermostable, with a half-life of 47 min at 100 degrees C, and exhibited an optimal temperature and pH of 90 degrees C and 7.0, respectively. Xylo-oligosaccharides were the enzymatic products of xylan hydrolysis, and the smallest degradation product was xylobiose, thus indicating that the enzyme was an endoxylanase. The enzyme was able to bind weakly to crystalline cellulose (Avicel) and more strongly to insoluble xylan in a substrate amount-and temperature-dependent manner.

Use of antiparkinsonian drugs in the Umbria Region

Discussion of differences between recommended guidelines and clinical practice is very useful in medicine. The use of a computerized database of all prescriptions of antiparkinsonian drugs enabled us to perform an epidemiological population-based study with low cost and in a relatively short time. We have identified 2 827 parkinsonian patients in November 2000 and estimate the number of patients taking dopaminoagonists aged >75 years, antidepressive drugs, and atypical neuroleptics.

Analysis of Thermal Adaptation in the HSL Enzyme Family

The recently solved three-dimensional (3D) structures of two thermostable members of the carboxylesterase/lipase HSL family, namely the Alicyclobacillus (formerly Bacillus) acidocaldarius and Archaeoglobus fulgidus carboxylesterases (EST2 and AFEST, respectively) were compared with that of the mesophilic homologous counterpart Brefeldine A esterase from Bacillus subtilis. Since the 3D homology models of other members of the HSL family were also available, we performed a structural alignment with all these sequences. The resulting alignment was used to assess the amino acid "traffic rule" in the HSL family. Quite surprisingly, the data were in very good agreement with those recently reported from two independent groups and based on the comparison of a huge number of homologous sequences from the genus Bacillus, Methanococcus and Deinococcus/Thermus. Taken as a whole, the data point to the statistical meaning of defined amino acid conversions going from psychrophilic to hyperthermophilic sequences. We identified and mapped several such changes onto the EST2 structure and observed that such mutations were localized mostly in loops regions or alpha-helices and were mostly excluded from the active site. A site-directed mutagenesis of two of the identified residues confirmed they were involved in thermal stability.

Spectral analysis of skin laser Doppler blood perfusion signal during cutaneous hyperemia in response to acetylcholine iontophoresis and ischemia in normal subjects

Spectral analysis of skin laser Doppler (LD) signal was performed using Fourier transformation in twelve healthy subjects in order to compare post-ischemic hyperemia and acetylcholine (ACh) iontophoresis tests for the exploration of cutaneous microcirculatory endothelial function. Within the frequency range studied of 0.009-1.6 Hz, five different frequency intervals were considered, arising from local (endothelial and myogenic) and central (neural, respiratory and cardiac) regulatory mechanisms. The power density (PD) for each of the five frequency intervals considered was measured in perfusion units (PU)/Hz, in each subject, before and in response to ischemia and to ACh iontophoresis, using a dedicated software. The relative contribution of each frequency interval was calculated as per cent rate between each PD and the sum of the PD of the five frequency interval considered. PD of LD signals in response to ischemia and Ach iontophoresis significantly increased for all the five frequency intervals considered. A significant increase (from 25.0+/-6.3 to 48.3+/-17.8; p<0.01) in the relative contribution of 0.009-0.02 frequency interval, referred to endothelium activity, was observed only in response to ACh iontophoresis. No significant increase in the relative power contribution was observed in response to ischemia for any of the five frequency intervals considered. These data suggest that ACh iontophoresis test is more adequate than post-ischemic hyperemia test in exploring the skin microcirculatory endothelial function in normal subjects.

Transcriptional response to DNA damage in the archaeon Sulfolobus solfataricus

Exposure of cells to DNA-damaging agents triggers a complex biological response involving cell cycle arrest and modulation of gene expression. Genomic sequencing has revealed the presence of archaeal genes homologous to components of the eucaryal nucleotide excision repair (NER) pathway, which is involved in the repair of ultraviolet (UV) light-induced DNA damage. However, the events involved in the cell response to UV irradiation and their regulation have not been studied in Archaea. We show here that UV radiation induces the formation of cyclobutane pyrimidine dimers (CPDs) in the hyperthermophilic archaeon Sulfolobus solfataricus, and that these lesions are efficiently repaired in vivo in the dark, suggesting that a NER pathway is active. DNA damage is a signal for concomitant growth arrest and transcriptional induction of the NER genes XPF, XPG and XPB. The cell response to UV irradiation includes transcriptional regulation of genes encoding two DNA binding proteins involved in chromosome dynamics. Moreover, several of these genes are also strongly induced by the intercalating agent actinomycin D. Thus, response to DNA damage in S.solfataricus has features essentially conserved in all three domains of life.

Characterization of brain malformations in the Baraitser-Winter syndrome and review of the literature

Baraitser-Winter syndrome is a rare autosomal recessive disorder characterized by developmental delay, dysmorphic features, and multiple malformations also involving the brain. We report a further case and provide updated information about an unrelated girl reported in the original paper by Baraitser and Winter. Both of them presented with pachygyria and the latter case was recently found to have subcortical band heterotopia on high resolution brain MRI imaging. These two patients and a review of the previously reported cases indicate that a specific pattern of brain anomalies falling in the agyria-pachygyria-band spectrum is associated with this dysmorphic syndrome, which may be considered another example of syndromic neuronal migration defect.

Biochemical characterization of a CDC6-like protein from the crenarchaeon Sulfolobus solfataricus

Cdc6 proteins play an essential role in the initiation of chromosomal DNA replication in Eukarya. Genes coding for putative homologs of Cdc6 have been also identified in the genomic sequence of Archaea, but the properties of the corresponding proteins have been poorly investigated so far. Herein, we report the biochemical characterization of one of the three putative Cdc6-like factors from the hyperthermophilic crenarchaeon Sulfolobus solfataricus (SsoCdc6-1). SsoCdc6-1 was overproduced in Escherichia coli as a His-tagged protein and purified to homogeneity. Gel filtration and glycerol gradient ultracentrifugation experiments indicated that this protein behaves as a monomer in solution (molecular mass of about 45 kDa). We demonstrated that SsoCdc6-1 binds single- and double-stranded DNA molecules by electrophoretic mobility shift assays. SsoCdc6-1 undergoes autophosphorylation in vitro and possesses a weak ATPase activity, whereas the protein with a mutation in the Walker A motif (Lys-59 --> Ala) is completely unable to hydrolyze ATP and does not autophosphorylate. We found that SsoCdc6-1 strongly inhibits the ATPase and DNA helicase activity of the S. solfataricus MCM protein. These findings provide the first in vitro biochemical evidence of a functional interaction between a MCM complex and a Cdc6 factor and have important implications for the understanding of the Cdc6 biological function.

A substrate-induced switch in the reaction mechanism of a thermophilic esterase: kinetic evidences and structural basis

The reaction mechanism of the esterase 2 (EST2) from Alicyclobacillus acidocaldarius was studied at the kinetic and structural level to shed light on the mechanism of activity and substrate specificity increase previously observed in its double mutant M211S/R215L. In particular, the values of kinetic constants (k1, k(-1), k2, and k3) along with activation energies (E1, E(-1), E2, and E3) were measured for wild type and mutant enzyme. The previously suggested substrate-induced switch in the reaction mechanism from kcat=k3 with a short acyl chain substrate (p-nitrophenyl hexanoate) to kcat=k2 with a long acyl chain substrate (p-nitrophenyl dodecanoate) was validated. The inhibition afforded by an irreversible inhibitor (1-hexadecanesulfonyl chloride), structurally related to p-nitrophenyl dodecanoate, was studied by kinetic analysis. Moreover the three-dimensional structure of the double mutant bound to this inhibitor was determined, providing essential information on the enzyme mechanism. In fact, structural analysis explained the observed substrate-induced switch because of an inversion in the binding mode of the long acyl chain derivatives with respect to the acyl- and alcohol-binding sites.

Glycosynthase-Catalysed syntheses at pH below neutrality

The use of the new glycosynthase Ta-beta-GlyE386G and of the already known Ss-beta-GlyE387G for the synthesis of interesting 4-methylumbelliferyl disaccharides and for the galactosylation of alpha- and beta-xylosides of 4-penten-1-ol is reported. The results show satisfactory yields of reaction in presence of low excesses of acceptors and demonstrated that the high activity of these enzymes at pH below neutrality is applicable in the transfer of glucose as well as of galactose from the preferred 2-NP-based donors.

A New Dehydrogenase Specific Towards Aromatic Aldehydes From A Halophilic Bacterium

A new enzyme showing a dehydrogenase activity towards aromatic aldehydes was isolated, purified and characterized from a halophilic strain isolated from saline environment. The enzyme is a monomer of 54 kDa; it is rather thermostable (optimal temperature: 50 degrees C) showing a broad spectrum of activity in a large pH range with the maximum at pH 9.5. The substrate specificity and the effect of ions were evaluated and compared with analogous described proteins.