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Biomedical subjects

G Geraci

Publications and source records attributed to G Geraci.

At least 19 recordsLinked to original sources
PubMed2001

DNA (cytosine-5) methyltransferase turnover and cellular localization in developing Paracentrotus lividus sea urchin embryo.

The turnover and localization of the enzyme DNA (cytosine-5) methyltransferase (Dnmt1) were studied during Paracentrotus lividus sea urchin embryo development using antibody preparations against the NH(2) and COOH-terminal regions of the molecule. The antibodies reveal, by Western blots and whole-mount analyses, that the enzyme is differently required during embryonic development. The changeover point is at blastula stage, where a proteolytic mechanism hydrolyses the enzyme present in all embryonic cells by removing a peptide of about 45 kDa from the amino terminal region of the 190 kDa enzyme initially synthesized on maternal transcripts. The resulting 145 kDa enzyme shows modified catalytic properties, different antibody reactivity and is rapidly destroyed in the few hours before gastrulation. At more advanced stages of development the enzyme is newly synthesized but only in particular cell types, among which neurons. The data show that Dnmt1 is removed from embryonic cells before gastrulation to be synthesized again at different levels in different cell types, indicating that the concentration of Dnmt1 is critical for the various differentiated cells of the developing sea urchin embryo.

Animals↗
PubMed2000

[Ventral hernia surgery].

BACKGROUND: A personal technique for polypropilene mesh implantation in the treatment of massive, boundary and recurrent incisional hernias is described. METHODS. DESIGN: retrospective evaluation of cases observed over the last 3 years. SETTING: division of General, Oncological and Thoracic Surgery, Department of Surgical and Anatomical Sciences, University of Palermo. SUBJECTS: twenty-four patients with massive, boundary and recurrent ventral hernia were selected and treated with this technique. INTERVENTIONS: the patients were submitted to implantation of a polypropilene prosthesis by using a part of the well vascularised hernial sac in order to close completely the peritoneal layer under the prosthesis (so as to avoid the contact between prosthesis and viscera) and to close the layer over the prosthesis (avoiding a contact between prosthesis and subcutis). MAIN OUTCOME MEASURES: morbidity and mortality have been evaluated. RESULTS: Patients were discharged from the 7th and 15th postoperative day. No mortality was recorded. In four out of 24 patients the following complications were observed: 1 case of high postoperative fever; 2 cases of superficial infection of the surgical wound; 1 case of wide cutaneous suppuration without prosthesis involvement. No recurrences were observed during the follow-up (6 months-3 year). CONCLUSIONS: Even if a scientific evaluation of the results is not possible due to the poor number of cases, short-term follow-up and unavailable randomized studies, this technique may be useful since it permits to avoid the contact between prosthesis and viscera, with lower postoperative adherences and the isolation of prosthesis from the subcutaneous tissue, sometimes involved in suppuration.

Adult↗
PubMed1999

Characterization of a new variant DNA (cytosine-5)-methyltransferase unable to methylate double stranded DNA isolated from the marine annelid worm Chaetopterus variopedatus.

The enzyme S-adenosylmethionine-DNA (cytosine-5)-methyltransferase has been identified, first time for invertebrates, in embryos of the marine polychaete annelid worm Chaetopterus variopedatus. The molecule has been isolated from embryos at 15 h of development. It is a single peptide of about 200 kDa molecular weight, cross-reacting with antibodies against sea urchin DNA methyltransferase. The enzymatic properties of the molecule are similar to those of Dnmt1 methyltransferases isolated from other organisms, but with the peculiarity to be unable to make 'de novo' methylation on double stranded DNA.

Animals↗
PubMed1999

[Video laparoscopy in abdominal emergencies].

BACKGROUND: Personal experience about the use of video laparoscopy (VL) in abdominal emergencies is reported. METHODS DESIGN: retrospective evaluation of patients observed in the last years. SETTING: General Surgery I. Policlinico, University of Palermo. SUBJECTS: 61 VL have been performed: 30 acute appendicitis, 21 acute cholecystitis, 4 perforated peptic ulcer, 1 haemoperitoneum by haemorrhaged luteal corpus, 2 pelvic inflammatory disease (PID), 1 terminal ileitis, 1 choledochal perforation after ERCP and 1 bleeding after CVL. INTERVENTIONS: the following interventions have been performed: 22 VL appendectomy, 8 VL-assisted appendectomy, 21 VL cholecystectomy, 1 VL duodenal suture, 3 minilaparotomic duodenal suture, 2 prophylactic VL-assisted appendectomy, in 1 patient with terminal ileitis and in 1 PID, 1 VL partial ovarian resection. In the case with choledochal perforation during ERCP a traditional cholecystectomy was performed with an outer biliary drainage. In the patient with bleeding after CVL the spontaneous haemostasis seen during VL was confirmed by laparotomy performed to exclude baro-haemostasis and to prevent from legal motivation. The procedure was only diagnostic in 1 patient with PID. MAIN OUTCOME MEASURES: the diagnostic and therapeutic value, versus traditional surgery have been valued. RESULTS: VL is useful both for a correct diagnosis and to lead a laparotomy if necessary, allowing an adequate peritoneal exploration and toilet without large incisions; the operation is therefore, in any case, less invasive. CONCLUSIONS: In our experience the usefulness of VL is clear in the suspect of acute appendicitis, acute cholecystitis, perforated peptic ulcer, haemoperitoneum and when diagnosis is not sure and in all other situations in which correct preoperative diagnosis is impossible. So this procedure is useful to make easy a correct diagnosis and to surgical treatment.

Abdomen, Acute↗
PubMed1999

[Cervico-mediastinal goiter. Our experience].

BACKGROUND: Personal experience about substernal goiter is reported. Stressing laid on the importance of definition: a goiter that is totally or in the most part below the superior thoracic outlet, with normal vascularization. METHODS DESIGN: retrospective evaluation of patients observed in the last six years. SETTING: General Surgery I, Policlinico, University of Palermo. SUBJECTS: four hundred ninety-six thyroidectomies have been performed, 32 patients (6.5%) were found to have substernal goiters. The age was between 42 and 86 years (middle age 59). Male/female = 1/1.9. Asymptomatics were 8 (25%). More frequent symptoms were airway compression (34%), hoarseness (9%), pain (9%), thyrotoxicosis (9%) and dysphagia (3%). INTERVENTIONS: total thyroidectomies have been always performed. MAIN OUTCOME MEASURES: the incidence, symptoms, short and long term complication have been valued. RESULTS: There were no postoperative bleeding or lesion of recurrent nerves or definitive hypoparathyroidism. Postoperative hypocalcemia was observed in 9 patients (28%). Only one temporary hypoparathyroidism (two months) was observed. In 2 patients the histologic examination revealed a papillar carcinoma. There were no intraoperative deaths. CONCLUSIONS: In personal experience the presence of substernal goiter is an indication for total thyroidectomy. The reasons for treating substernal goiter surgically are the following: no effective medical treatment is available; respiratory compromise, thyrotoxicosis, dysphagia, or malignancy can develop in long-standing goiters; surgery, in skilled hands, presents minimal morbidity.

Adult↗
PubMed1999

[The surgical approach to non-neoplastic abdominal pathology in the geriatric patient].

BACKGROUND: The authors evaluate the most suitable approach to be used in elderly patients suffering from non-neoplastic abdominal pathology. METHODS: A retrospective evaluation was made of cases observed over the past two years. Follow-up continued for at least three months after treatment. SETTING: General Surgery 1, Department of Surgical and Anatomic Disciplines, Policlinico, University of Palermo. PATIENTS: A total of 92 patients were treated aged between 65 and 94 years old (mean age 79.5). The most frequently observed pathologies were cholelithiasis and hernia, treated both electively and in emergency. OPERATIONS: 76 patients were treated electively and 16 underwent emergency surgery. Parameters examined: The authors evaluated postoperative progress, morbidity and mortality. RESULTS: Morbidity was equal to 6.5%. Death occurred in three patients, one of whom had been operated a month earlier. CONCLUSIONS: Surgery is considered appropriate in the elderly patient provided an adequate pre-, intra- and postoperative approach is used. The preoperative phase should include a multidisciplinary evaluation to assess surgical risk (ASA and APACHE). During surgery, the most beneficial solution should be found which takes account of the patient's life expectancy; whenever possible, is it advantageous to resort to video-laparoscopy owing to the diagnostic accuracy of this method, as well as the capacity to adjust subsequent surgery whether it is performed using video-assisted laparoscopy or targeted mini-laparotomy. This causes less surgical aggression and therefore a more comfortable postoperative recovery. During the latter phase, vital and biohumoral parameters should be accurately monitored to ensure the prompt recognition of organic collapse and/or metabolic disorders consequent to surgical stress.

Abdomen↗
PubMed1999

Oxidative stress and antioxidants at skin biosurface: a novel antioxidant from lemon oil capable of inhibiting oxidative damage to the skin.

Atmospheric pollutants are an important source of oxidative and nitrosative stress both to terrestrial plants and to animals. Skin, which has a highly differentiated and certainly complex organizational structure, is particularly vulnerable to free radical damage because of its contact with oxygen and with other environmental stimuli. Fruit and vegetables contain several classes of compounds that when ingested can potentially contribute to antioxidant defenses. In the present study we employed a novel gas chromatographic method to assess the antioxidant properties of a natural compound isolated from lemon oil, which we have called Lem1. We provide experimental evidence that Lem1 is endowed with a strong antioxidant activity and that it is capable of inhibiting free radical-mediated reactions, as evaluated in vitro and in vivo. The present study extends our previous findings and demonstrates that topical application of Lem1 in healthy volunteers significantly increases the antioxidative potential of skin biosurface, thus highlighting the effectiveness of a natural antioxidant biotechnology in the antiaging management of skin.

Administration, Topical↗
PubMed1998

Cooperative mechanism in the homodimeric myoglobin from Nassa mutabilis.

Oxygen binding and spectroscopic properties of the homodimeric myoglobin (Mb) from the prosobranchia sea snail Nassa mutabilis have been investigated. Oxygen equilibrium curves are pH-independent and cooperative with P50 = 5 +/- 1 mmHg and n approximately 1.5. Circular dichroism spectra of the oxygenated and deoxygenated form of N. mutabilis Mb are superimposable between 190 and 250 nm, suggesting a mechanism for cooperative ligand binding that does not involve changes in the alpha-helical content of the whole protein. The oxygen dissociation process is biphasic and pH-dependent, with different pKa values (=6.7 +/- 0.2 and 8.5 +/- 0.3) for the two phases. Moreover, the activation energy is essentially the same for both oxygen dissociation processes (Ea = 56.4 +/- 2.1 kJ/mol for the fast phase, and Ea = 53.8 +/- 1.9 kJ/mol for the slow phase), indicating that the rate difference for O2 dissociation between the diliganded and the monoliganded species is mostly dependent on a variation of the activation entropy. Ferrous nitrosylated N. mutabilis Mb shows, at alkaline and neutral pH, axial and rhombic X-band EPR signals, respectively, which display below pH 6 a three-hyperfine pattern typical of five-coordination. The results presented here suggest that in N.mutabilis Mb the kinetic control of cooperativity operates through a mechanism never observed before in other hemoproteins, which requires a ligand-linked large enhancement for the value of the oxygen association process in a molecule not undergoing changes in quaternary structure.

Animals↗
PubMed1998

Organization and nucleotide sequence of the cluster of five histone genes in the polichaete worm Chaetopterus variopedatus: first record of a H1 histone gene in the phylum Annelida.

Histone genes were identified and their nucleotide sequences were determined in the polychaete marine worm Chaetopterus variopedatus. The genes are organized in about 390 clusters of 7.3 kbp. Each cluster contains one copy of the five histone genes. The H1 histone gene present in the clusters is the first ever isolated in the phylum Annelida. The cluster has the unique peculiarity that all genes contain both the replication-dependent and the replication-independent 3' mRNA termination signals. Despite the differences in cluster organization and transcription polarity of the individual histone genes between C. variopedatus and Platynereis dumerilii, the other annelid in which histone genes have been studied, phylogenetic analysis of the encoded amino acid sequences clearly groups together those two organisms in a tree in which the other studied worms find closely related positions on the same evolutionary branch.

Amino Acid Sequence↗
PubMed1997

Genome methylation of the marine annelid worm Chaetopterus variopedatus: methylation of a CpG in an expressed H1 histone gene.

Hydrolysis by methylation-dependent restriction enzymes shows that the genomic DNA of the polychaete annelid worm Chaetopterus variopedatus is methylated. Electrophoretic analyses of the digestion products indicate that the degree of methylation is lower in adult tissues than in sperm and embryonic DNA. 5-Methylcytosine was identified by HPLC, absorption spectroscopy and mass spectrometry analyses of free bases obtained by acid hydrolysis of the DNA. An average value of 1.6% methylated cytosines was determined in sperm DNA. Partial methylation was also found in an actively expressed H1 histone gene. This is the first time that genomic DNA methylation is demonstrated to occur in a worm.

Animals↗
PubMed1997

The S.//.A.IG amino acid motif is present in a replication dependent late H3 histone variant of P. lividus sea urchin.

A novel gene encoding a new H3 histone varian (H3L) has been identified in P. lividus sea urchin embryo. It encodes a H3 histone protein showing the S.//.A.IG amino acid motif typical of the replication independent H3.3 variants but in a mRNA showing the 3' terminal stem-loop nucleotide sequence that is typical of the replication dependent variants. The gene is intronless, the corresponding short transcript is non-polyadenyl ated and its expression is replication dependent with a timing of late variant. The new H3 variant is expressed as a minor component with respect to a major replication dependent late H3 histone here identified by partial cDNA sequence. These results show that classification of histones in replication dependent and independent variants only on the basis of their amino acid sequences should be reconsidered.

Amino Acid Sequence↗
PubMed1997

Two periods of sensitivity to mutagens in induced Mel cells with different outcomes.

Mouse erythroleukemia (Mel) cells are particularly sensitive to mutagenic agents between 18 and 24 h from the start of induction (Foresti, M.L. Gaudio, G. Geraci and P. Manduca (1986) Inhibition of dimethyl sulfoxide induced erythropoietic differentiation of murine erythroleukemia cells in culture. Cancer Res., 46, 6260-6263). We show here the occurrence of another period of sensitivity during the initial 5 h after the addition of the inducer dimethyl sulfoxide (DMSO) to the culture medium. The sensitivity to the mutagenic action of a sublethal 3-s pulse of UV light (13.5 J/m2) was monitored on the progeny of the irradiated cells at day 5 after the start of induction. The effects were analysed on functions strictly linked to the final expression of the differentiated phenotype: hemoglobin concentration, percent cells producing hemoglobin (%B+), activity of delta-amino levulinic acid dehydrase (ALA-DH) and presence of globins. Each function appeared differently and selectively affected in the progeny of the cells depending on the exact time of irradiation during the period of sensitivity Specifically, cells irradiated at hour 3 after induction show both hemoglobin concentration and ALA-DH activity values increased by a factor 3 over controls. Cells irradiated at hour 5 show an almost complete halt in cell induction and the other tested functions show minimal values. Cells are nearly insensitive to irradiation at later times, until hour 20, after which a second period of sensitivity with peak value at hour 22 occurs at which time hemoglobin concentration in the progeny of irradiated cells is increased by a factor 3 over controls, ALA-DH activity is increased by a factor 15 while percent B+ value is at its minimum. The differential effects of UV irradiation on Mel cell functions in the first and in the second period of sensitivity to mutagens confirm the hypothesis that the consequences of a mutational event are strictly dependent on the functional state of the cell. The 1-5 h period of sensitivity in which Mel cells fix the effects of the mutagen in their genome corresponds to increased thymidine incorporation not correlated with cell duplication.

Animals↗
PubMed1996

Isolation of cDNA clones encoding DNA methyltransferase of sea urchin P. lividus: expression during embryonic development.

A full-length cDNA, encoding a DNA (cytosine-5)-methyltransferase (DNA MTase), has been assembled from a series of overlapping cDNA clones isolated from P. lividus sea urchin embryo cDNA libraries. The cDNA contains 103 bp 5'-UTR, 4839 bp open reading frame corresponding to a 1612 amino acids (aa) protein and 2240 bp 3'-UTR including a terminal 18-bp poly(A) tail. Both the cDNA and the encoded protein are the longest so far reported for DNA MTases. The protein shows five distinct and sequential regions of identity with the other animal DNA MTases, with values of identity from zero to 80%. Northern blot analyses reveal a single RNA band of about 7.5 kb in length showing a highly regulated concentration pattern during development with peak value at the four blastomere stage.

Amino Acid Sequence↗
PubMed1996

In situ hybridization analysis of globin mRNAs in the primitive erythroid cells of the chick embryo.

The possibility that the minor embryonic chick hemoglobins might be present in a particular subgroup of primitive erythroid cells has been investigated by in situ hybridization. Probe to detect the mRNA for the alpha A globin chain of the minor embryonic hemoglobin was used, and the results of the hybridization were compared with those obtained using as probes the cDNAs for total globin mRNAs. All erythroid cells circulating in a 4-day-old chick embryo gave positive signals with both probes at an approximately constant ratio. This shows that all cells contain a similar assortment of hemoglobin types, excluding the possibility that a subgroup might contain the minor primitive hemoglobins exclusively. However, the cells are not homogeneous, since about 10% of them show a distinctly higher concentration of mRNA of all globin types.

Animals↗
PubMed1995

Resonance Raman studies of the heme active site of the homodimeric myoglobin from Nassa mutabilis: a peculiar case.

A spectroscopic investigation by resonance Raman has been carried out at pH 7.0 in 0.1 M phosphate buffer on the cooperative homodimeric myoglobin from Nassa mutabilis. The study has been performed on the unligated ferrous form, as well as on the ligated species MbO2 and MbC, and on the ferric form met-Mb. Two v(C = C) vinyl stretching modes have been observed in all the investigated forms, reflecting different degrees of vinyl conjugation with the porphyrin ring, as a consequence of a strongly asymmetric environment for the two side groups of the heme. Furthermore, the ferric form displays a hexacoordinate low-spin heme, which suggests the presence of an endogenous ligand bound to the Fe atom. The frequency of the v(Fe-Im) stretching mode of Mb from Nassa mutabilis shifts down by 4 cm-1 as compared with that of horse heart myoglobin, reflecting a protein-induced proximal strain as a result of heme-heme interaction due to the close proximity of the two hemes in the dimer. The lower frequency of the v(Fe-Im) stretching mode agrees well with the lower affinity for oxygen binding found for Nassa mutabilis Mb and with the slight heme core expansion with respect to horse heart Mb, suggesting a critical role for the Fe-His bond on the heme's function and structure.

Animals↗
PubMed1995

DNA methyltransferase activity in the early stages of a sea urchin embryo. Evidence of differential control.

The specific activity of DNA methyltransferase increases in the nuclei of Sphaerechinus granularis sea urchin embryos at increasing stages of development. The activity reaches maximal value at about 20 h of growth, when embryos are at the mesenchyme blastula stage, then abruptly decreases and is essentially zero at about 35 h of development, when embryos are at the early gastrula stage. Both the increase and the drop of the activity are faster than embryonic cell duplication indicating that the enzyme is under strict control during development and that, in the more advanced embryo, a mechanism is activated to specifically block its activity.

Animals↗
PubMed1995

Cloning and characterization of a developmentally regulated sea urchin cDNA encoding glutamine synthetase.

A 2935-bp cDNA clone encoding glutamine synthetase (GS) was isolated from a cDNA library prepared from four-blastomere Paracentrotus lividus sea urchin embryos. The sequence consists of a 75-bp 5' untranslated region (5'-UTR) followed by a 1095-bp coding region corresponding to a 365-amino-acid (aa) protein, a 1747-bp 3'-UTR and a terminal 18-bp poly(A) tail. The encoded protein shows about 66% identical residues, as compared with human and lobster class-II GS. The sequence contains the Mn(2+)-binding aa and the highly conserved aa regions observed in other GS. Northern blot analyses show that the GS mRNA is present in the sea urchin egg and is developmentally regulated in the embryo.

Amino Acid Sequence↗