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Biomedical subjects

G Morelli

Publications and source records attributed to G Morelli.

At least 37 records · Page 2Linked to original sources
PubMed2001

The arabidopsis ATHB-8 HD-zip protein acts as a differentiation-promoting transcription factor of the vascular meristems.

ATHB-8, -9, -14, -15, and IFL1/REV are members of a small homeodomain-leucine zipper family whose genes are characterized by expression in the vascular tissue. ATHB-8, a gene positively regulated by auxin (Baima et al., 1995), is considered an early marker of the procambial cells and of the cambium during vascular regeneration after wounding. Here, we demonstrate that although the formation of the vascular system is not affected in athb8 mutants, ectopic expression of ATHB-8 in Arabidopsis plants increased the production of xylem tissue. In particular, a careful anatomical analysis of the transgenic plants indicated that the overexpression of ATHB-8 promotes vascular cell differentiation. First, the procambial cells differentiated precociously into primary xylem. In addition, interfascicular cells also differentiated precociously into fibers. Finally, the transition to secondary growth, mainly producing xylem, was anticipated in transgenic inflorescence stems compared with controls. The stimulation of primary and secondary vascular cell differentiation resulted in complex modifications of the growth and development of the ATHB-8 transgenic plants. Taken together, these results are consistent with the hypothesis that ATHB-8 is a positive regulator of proliferation and differentiation, and participates in a positive feedback loop in which auxin signaling induces the expression of ATHB-8, which in turn positively modulates the activity of procambial and cambial cells to differentiate.

Arabidopsis↗
PubMed2001

Older adult multiorgan donors and misdiagnosed tumor.

BACKGROUND: In these last years, the increase in organ donations is mostly due to old patients died of primary vascular cerebral diseases. In this kind of patients some undiagnosed cancers can be present and can be transmitted to the receiver. Aim of this study is to carry out a research in order to identify any undiagnosed cancer which can be present during the period of encephalic death. METHODS: Perspective study: hospitals type II and type III. Polyvalent intensive care. From January 1999 to July 2000 encephalic death has been ascertained in 16 patients. The research of tumor markers has been carried out on these patients. Further diagnostic researches have been carried out on patients who had anomalous values. RESULTS: The organ donations have not been made by eight patients: five for family refusal, one for medical contraindications, two for the presence of undiagnosed tumor (PSA 1100 ng/ml and CEA 129.5 ng/ml) confirmed by prostatic and abdominal US imaging. A patient with CA 19-9 89.5 ng/ml has not been examined, because of the family refusal to donation. A patient with PSA of 135 ng/ml had a negative response from the anal scanner, and so the prosecution of the donation has not been interrupted. A blood sample has been taken and a biopsy of the prostate has been made to confirm the absence of neoplasm. CONCLUSIONS: It is necessary to make a careful examination of the organ donor to check if some cancers are present. Tumor markers cannot be used to make a diagnosis of a cancer, but they can be used as guide for further researches. In spite of all the diagnostic efforts, the objective evaluation of the surgeon is still the most important factor like the biopsy of all the suspected lesions during an operation and the autopsy.

Adult↗
PubMed2000

Complete DNA sequence of a serogroup A strain of Neisseria meningitidis Z2491.

Neisseria meningitidis causes bacterial meningitis and is therefore responsible for considerable morbidity and mortality in both the developed and the developing world. Meningococci are opportunistic pathogens that colonize the nasopharynges and oropharynges of asymptomatic carriers. For reasons that are still mostly unknown, they occasionally gain access to the blood, and subsequently to the cerebrospinal fluid, to cause septicaemia and meningitis. N. meningitidis strains are divided into a number of serogroups on the basis of the immunochemistry of their capsular polysaccharides; serogroup A strains are responsible for major epidemics and pandemics of meningococcal disease, and therefore most of the morbidity and mortality associated with this disease. Here we have determined the complete genome sequence of a serogroup A strain of Neisseria meningitidis, Z2491. The sequence is 2,184,406 base pairs in length, with an overall G+C content of 51.8%, and contains 2,121 predicted coding sequences. The most notable feature of the genome is the presence of many hundreds of repetitive elements, ranging from short repeats, positioned either singly or in large multiple arrays, to insertion sequences and gene duplications of one kilobase or more. Many of these repeats appear to be involved in genome fluidity and antigenic variation in this important human pathogen.

Antigenic Variation↗
PubMed2000

Psychosocial factors and male seminal parameters.

The relationships between (a) alexithymia, (b) extroversion (E), neuroticism (N), psychoticism (P), (c) coping style towards stressors, and seminal parameters, were assessed in 132 males on their first seminal fluid examination by means of a multivariate approach. They were given the TAS-20, the EPQ, and the Coping Inventory for Stressful Situations (CISS). Seminal parameters were: (1) sperm concentration; (2) total sperm count; (3) forward motility; (4) atypical forms. Multiple regressions considering quantitative parameters of seminal status as criterion showed a negative relationship with P, difficulty describing feelings (DDF), while a positive relationship was found for N, and emotion-oriented coping. A discriminant analysis also showed that P, N and DDF distinguished between two groups of normozoospermic and oligozoospermic subjects with a high probability of correct classifications. Results confirm the hypothesis that biological and psychological variables are not completely independent or randomly related in people with an impaired seminal status, although the correlations between psychosocial and biological data are not very strong.

Adaptation, Psychological↗
PubMed2000

Attachment and culture. Security in the United States and Japan.

Attachment theorists maintain that cultural differences are relatively minor, and they focus on universals. Here the authors highlight evidence of cultural variations and note ways in which attachment theory is laden with Western values and meaning. Comparisons of the United States and Japan highlight the cultural relativity of 3 core hypotheses of attachment theory: that caregiver sensitivity leads to secure attachment, that secure attachment leads to later social competence, and that children who are securely attached use the primary caregiver as a secure base for exploring the external world. Attachment theorists use measures of sensitivity, competence, and secure base that are biased toward Western ways of thinking: The measures emphasize the child's autonomy, individuation, and exploration. In Japan, sensitivity, competence, and secure base are viewed very differently, calling into question the universality of fundamental tenets of attachment theory. The authors call for an indigenous approach to the psychology of attachment.

Adult↗
PubMed2000

Immigrant-Chinese and Euro-American parents' physical closeness with young children: themes of family relatedness.

This study examined cultural differences in the expression and meaning of physical closeness. Findings indicated that immigrant-Chinese parents, as compared with Euro-American parents, sleep in closer proximity with their children; more often view independence as children growing with the family; are more likely to emphasize the family unit; and place greater importance on inhibition of expression, adherence to correct values, and hierarchy of relations. Euro-Americans, by contrast, are more accepting of nudity; place more emphasis on psychological benefits of physical closeness and on the child's expression of wants and feelings; more often view independence as celebrating the child's distinctiveness; and place greater importance on intimacy, pleasure, and spousal exclusiveness. The authors suggest that closeness is characterized by an overarching theme of harmony in immigrant-Chinese families and by an overarching theme of romance in Euro-American families.

Asian↗
PubMed2000

Microheterogeneity of serogroup A (subgroup III) Neisseria meningitidis during an outbreak in northern Ghana.

During a meningitis outbreak in the eastern subdistrict of the Kassena-Nankana District of the Upper East Region of Ghana, we analysed cerebrospinal fluid from suspected meningitis cases for the most common causative organisms. In 50 of 92 samples analysed, serogroup A Neisseria meningitidis were detected. The ages of serogroup A N. meningitidis patients ranged from 4 months to 64 years. The case fatality ratio was 20%. Coma or stupor on presentation worsened the prognosis. All serogroup A N. meningitidis isolates recovered revealed the A: 4: P1.9, 20 phenotype characteristic for the subgroup III clonal grouping. No evidence for resistance to penicillin G, chloramphenicol, cefotaxime, ciprofloxacin, rifampicin or tetracycline was found. All strains were resistant to sulphadiazine. Restriction analysis patterns of opa, iga and ingA genes were characteristic for the majority of N. meningitidis serogroup A subgroup III bacteria isolated in Africa after the 1987 epidemic in Mecca. Differences in pulsed-field gel electrophoresis patterns of NheI and SpeI digested DNA revealed microheterogeneity among the Ghanaian isolates.

Adolescent↗
PubMed1999

Yersinia pestis, the cause of plague, is a recently emerged clone of Yersinia pseudotuberculosis.

Plague, one of the most devastating diseases of human history, is caused by Yersinia pestis. In this study, we analyzed the population genetic structure of Y. pestis and the two other pathogenic Yersinia species, Y. pseudotuberculosis and Y. enterocolitica. Fragments of five housekeeping genes and a gene involved in the synthesis of lipopolysaccharide were sequenced from 36 strains representing the global diversity of Y. pestis and from 12-13 strains from each of the other species. No sequence diversity was found in any Y. pestis gene, and these alleles were identical or nearly identical to alleles from Y. pseudotuberculosis. Thus, Y. pestis is a clone that evolved from Y. pseudotuberculosis 1,500-20,000 years ago, shortly before the first known pandemics of human plague. Three biovars (Antiqua, Medievalis, and Orientalis) have been distinguished by microbiologists within the Y. pestis clone. These biovars form distinct branches of a phylogenetic tree based on restriction fragment length polymorphisms of the locations of the IS100 insertion element. These data are consistent with previous inferences that Antiqua caused a plague pandemic in the sixth century, Medievalis caused the Black Death and subsequent epidemics during the second pandemic wave, and Orientalis caused the current plague pandemic.

Alleles↗
PubMed1999

Endorectal coil MR imaging findings in hemospermia.

The purpose of this study was to illustrate the spectrum of abnormalities found at endorectal coil magnetic resonance (MR) imaging in patients with hemospermia. Ninety patients aged between 23 and 71 years (mean age 41 years) presenting with hemospermia underwent evaluation with endorectal coil MR imaging at 1.5 T. Duration of hemospermia ranged between 5 days and 4 years (mean 15 months). MR examination protocol included T1-weighted spin-echo (SE) and T2-weighted fast SE MR images obtained in the sagittal, coronal, and axial planes. Abnormalities were observed on endorectal-coil MR images in 49 of 90 patients (54%). Blood within the seminal vesicle or the ejaculatory duct was recognized in 23 of 90 patients (25%). Dilatation of the seminal vesicles or the ejaculatory duct was observed in 31 of 90 patients (34%). Cystic lesions were identified in 14 cases, eight of which involved the utriculus and six the ejaculatory duct. Calculi within the seminal vesicles were depicted in seven patients. No malignant disease was demonstrated. In conclusion, despite the evidence that hemospermia is most often a benign and self-limiting condition, we found that endorectal coil MR imaging can detect abnormal findings in more than half of the patients, and may be helpful in assessing the level at which hemorrhage occurred and in defining the cause of the disease.

Adult↗
PubMed1999

Hodgkin's lymphoma: an isolated case of involvement of the ureter.

We report the case of a man in which a Hodgkin's lymphoma involved the ureter as the very first clinical situs of the disease. Ureteral involvement in lymphomas is very rare (0.86%-7% and 1%-16%, found in two studies, respectively, of cases of patients with lymphoma examined post mortem) and when it does occur it is secondary to renal involvement or retroperitoneal adenopathies. It is by all means exceptional as an isolated situs of disease. Those cases reported in the literature as presenting lymphomatous involvement of the ureter have always been diagnosed as Non-Hodgkin's lymphomas.

Combined Modality Therapy↗
PubMed1999

Recombination and clonal groupings within Helicobacter pylori from different geographical regions.

A collection of 20 strains of Helicobacter pylori from several regions of the world was studied to better understand the population genetic structure and diversity of this species. Sequences of fragments from seven housekeeping genes (atpA, efp, mutY, ppa, trpC, ureI, yphC ) and two virulence-associated genes (cagA, vacA) showed high levels of synonymous sequence variation (mean percentage Ks of 10-27%) and lower levels of non-synonymous variation (mean percentage Ka of 0.2-5.6%). Cluster analysis of pairwise differences between alleles revealed the existence of two weakly clonal groupings, which included half of the strains investigated. All six strains isolated from Japanese and coastal Chinese were assigned to the 'Asian' clonal grouping, probably reflecting descent from a distinct common ancestor. The clonal groupings were not totally uniform; recombination, as measured by the homoplasy test and compatibility matrices, was extremely common within all genes tested, except cagA. The fact that clonal descent could still be discerned despite such frequent recombination possibly reflects founder effects and geographical separation and/or selection for particular alleles of these genes.

Aldose-Ketose Isomerases↗
PubMed1999

The opcA and (psi)opcB regions in Neisseria: genes, pseudogenes, deletions, insertion elements and DNA islands.

Previous data have indicated that the opc gene encoding an immunogenic invasin is specific to Neisseria meningitidis (Nm) and is lacking in Neisseria gonorrhoeae (Ng). The data presented here show that Nm and Ng both contain two paralogous opc-like genes, opcA, corresponding to the former opc gene, and (psi)opcB, a pseudogene. The predicted OpcA and OpcB proteins possess transmembrane regions with conserved non-polar faces but differ extensively in four of the five surface-exposed loops. Gonococcal OpcA was expressed weakly under in vitro conditions, and it is unknown whether these bacteria can express this protein at high levels. Analysis of the sequences flanking opcA and (psi)opcB revealed a framework of conserved housekeeping genes interspersed with DNA islands. These regions also contained several pseudogenes, deletions and IS elements, attesting to considerable genome plasticity. Both opcA and (psi)opcB are located on DNA islands that have probably been imported from unrelated bacteria. A third island encodes the dcmD/dcrD R/M genes in Ng versus a small open reading frame in most strains of Nm. Rare strains of Nm were identified in which the R/M island has been imported. DNA islands in Nm and Ng seem to have been acquired by recombination via conserved flanking housekeeping genes rather than by insertion of mobile genetic elements.

Adhesins, Bacterial↗
PubMed1999

Shade avoidance responses are mediated by the ATHB-2 HD-zip protein, a negative regulator of gene expression.

The ATHB-2 gene encoding an homeodomain-leucine zipper protein is rapidly and strongly induced by changes in the ratio of red to far-red light which naturally occur during the daytime under the canopy and induce in many plants the shade avoidance response. Here, we show that elevated ATHB-2 levels inhibit cotyledon expansion by restricting cell elongation in the cotyledon-length and -width direction. We also show that elevated ATHB-2 levels enhance longitudinal cell expansion in the hypocotyl. Interestingly, we found that ATHB-2-induced, as well as shade-induced, elongation of the hypocotyl is dependent on the auxin transport system. In the root and hypocotyl, elevated ATHB-2 levels also inhibit specific cell proliferation such as secondary growth of the vascular system and lateral root formation. Consistent with the key role of auxin in these processes, we found that auxin is able to rescue the ATHB-2 lateral root phenotype. We also show that reduced levels of ATHB-2 result in reciprocal phenotypes. Moreover, we demonstrate that ATHB-2 functions as a negative regulator of gene expression in a transient assay. Remarkably, the expression in transgenic plants of a derivative of ATHB-2 with the same DNA binding specificity but opposite regulatory properties results in a shift in the orientation of hypocotyl cell expansion toward radial expansion, and in an increase in hypocotyl secondary cell proliferation. A model of ATHB-2 function in the regulation of shade-induced growth responses is proposed.

Arabidopsis↗
PubMed1998

The Arabidopsis Athb-8, -9 and -14 genes are members of a small gene family coding for highly related HD-ZIP proteins.

We report the isolation and characterization of two Arabidopsis homeobox genes highly related to the Athb-8 gene. The full-length cDNAs encode proteins of 841 and 852 amino acids which we have designated Athb-9 and -14, respectively. Athb-8, -9 and -14 are members of a small family of HD-Zip proteins (HD-ZIP III) characterized by a HD-Zip motif confined to the N-terminus of the polypeptide. The spatial organization of the HD-Zip domain of Athb-8, -9 and -14 is different from that of the Athb-1 (a member of the HD-ZIP I family) and Athb-2 (a member of the HD-ZIP II family) HD-Zip domains. DNA binding analysis performed with random-sequence DNA templates showed that the Athb-9 HD-Zip (HD-Zip-9) domain, but not the Athb-9 HD alone, binds to DNA. The HD-Zip-9 domain recognizes a 11 bp pseudopalindromic sequence (GTAAT(G/C)ATTAC), as determined by selecting high-affinity binding sites from random-sequence DNA. Moreover, gel retardation assays demonstrated that the HD-Zip-9 domain binds to DNA as a dimer. These data support the notion that the HD-ZIP III domain interacts with DNA recognition elements in a fashion similar to the HD-ZIP I and II domains.

Amino Acid Sequence↗
PubMed1998

Free recombination within Helicobacter pylori.

Sequences of three gene fragments (flaA, flaB, and vacA) from Helicobacter pylori strains isolated from patients in Germany, Canada, and South Africa were analyzed for diversity and for linkage equilibrium by using the Homoplasy Test and compatibility matrices. Horizontal genetic exchange in H. pylori is so frequent that different loci and polymorphisms within each locus are all at linkage equilibrium. These results indicate that H. pylori is panmictic. Comparisons with sequences from Escherichia coli, Neisseria meningitidis, and Drosophila melanogaster showed that recombination in H. pylori was much more frequent than in other species. In contrast, when multiple family members infected with H. pylori were investigated, some strains were indistinguishable at all three loci. Thus, H. pylori is clonal over short time periods after natural transmission.

Alleles↗
PubMed1998

Multilocus sequence typing: a portable approach to the identification of clones within populations of pathogenic microorganisms.

Traditional and molecular typing schemes for the characterization of pathogenic microorganisms are poorly portable because they index variation that is difficult to compare among laboratories. To overcome these problems, we propose multilocus sequence typing (MLST), which exploits the unambiguous nature and electronic portability of nucleotide sequence data for the characterization of microorganisms. To evaluate MLST, we determined the sequences of approximately 470-bp fragments from 11 housekeeping genes in a reference set of 107 isolates of Neisseria meningitidis from invasive disease and healthy carriers. For each locus, alleles were assigned arbitrary numbers and dendrograms were constructed from the pairwise differences in multilocus allelic profiles by cluster analysis. The strain associations obtained were consistent with clonal groupings previously determined by multilocus enzyme electrophoresis. A subset of six gene fragments was chosen that retained the resolution and congruence achieved by using all 11 loci. Most isolates from hyper-virulent lineages of serogroups A, B, and C meningococci were identical for all loci or differed from the majority type at only a single locus. MLST using six loci therefore reliably identified the major meningococcal lineages associated with invasive disease. MLST can be applied to almost all bacterial species and other haploid organisms, including those that are difficult to cultivate. The overwhelming advantage of MLST over other molecular typing methods is that sequence data are truly portable between laboratories, permitting one expanding global database per species to be placed on a World-Wide Web site, thus enabling exchange of molecular typing data for global epidemiology via the Internet.

Bacterial Typing Techniques↗