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Biomedical subjects

G Servillo

Publications and source records attributed to G Servillo.

At least 37 records · Page 2Linked to original sources
PubMed1997

Lysosomal alpha-mannosidases of mouse tissues: characteristics of the isoenzymes, and cloning and expression of a full-length cDNA.

Lysosomal alpha-d-mannosidase from mouse tissues was separated into its constituent isoenzymes by DEAE-cellulose chromatography. Forms corresponding to the human isoenzymes B and A were present in testis, brain, spleen and kidney, whereas in epididymis and liver only the B form was present. Murine alpha-mannosidases A and B are glycoproteins and have pH optima, thermal stabilities and molecular masses similar to those of the human isoenzymes. A full-length cDNA (3.1 kb) containing the complete coding sequence for alpha-mannosidase was isolated from a mouse macrophage cDNA library. Comparison of the deduced amino acid sequences of human and mouse alpha-mannosidases showed that they had 75% identity and 83% similarity. Expression of this cDNA in COS cells showed that both the A and the B isoenzymes can arise from a single transcript. Northern blotting analysis showed a 10-fold range in the abundance of alpha-mannosidase mRNA in mouse tissues, with the highest levels found in epididymis, and the lowest in liver.

Amino Acid Sequence↗
PubMed1997

Cyclic AMP signalling and cellular proliferation: regulation of CREB and CREM.

In eukaryotes, transcriptional regulation upon stimulation of the adenylyl cyclase signalling pathway is mediated by a family of cAMP-responsive nuclear factors. This family consists of a large number of members which may act as activators or repressors. These factors contain the basic domain/leucine zipper motifs and bind as dimers to cAMP-response elements (CRE). The function of CRE-binding proteins (CREB) is modulated by phosphorylation by the cAMP-dependent protein kinase. The ICER (inducible cAMP early repressor) protein is the only inducible member of this family and is a product of the CREM gene. The induction of this powerful repressor is likely to be important for the transient nature of cAMP-induced gene expression. CREB proteins have been found to play an important role in the physiology of neuroendocrine functions. In addition, recent results indicate that CREB and CREM could be involved in the proliferation of hepatocytes which follows partial hepatectomy.

Cell Division↗
PubMed1997

Cyclic AMP signalling pathway and cellular proliferation: induction of CREM during liver regeneration.

The CREM gene encodes both activators and repressors of cAMP-induced gene expression. An isoform of CREM encodes the powerful transcriptional repressor ICER (Inducible cAMP Early Repressor), which has been shown to be inducible by virtue of an alternative, intronic promoter. The CREM gene belongs to the early response class and displays a characteristic neuroendocrine cell- and tissue-specific expression. To date ICER inducibility has been described in non-replicating, terminally differentiated tissues. In this paper we document a robust induction of CREM expression in the regenerating rat liver after partial hepatectomy. This represents the first link of inducible CREM expression to the phenomenon of cellular proliferation. Furthermore, it represents the first example of transcriptional activation of a cAMP-responsive factor in the regenerating liver. This has significant physiological relevance since the adenylate cyclase signalling pathway is strongly implicated in liver regeneration. Finally, we show that the repressor ICER is inducible in the hepatoma cell line H35 upon activation of the adenylate cyclase and phosphorylation of the activator CREB.

Animals↗
PubMed1997

Effects of ventilation in ventral decubitus position on respiratory mechanics in adult respiratory distress syndrome.

OBJECTIVE: To assess the potential benefits of a period of ventilation in ventral decubitus (VD) on oxygenation and respiratory mechanics in the adult respiratory distress syndrome (ARDS). DESIGN: In a stable condition during baseline ventilation in dorsal decubitus (DD), after 15 min of ventilation in VD and after 10 min of restored DD, the following parameters were studied: arterial blood gas tension, haemodynamics and static respiratory compliance (Crs), evaluated with the rapid airway occlusion technique. SETTING: The study was completed in the intensive care units of university hospitals as part of the management of the patients studied. PATIENTS: Twelve patients (7 males, 5 females, mean age 51.8 +/- 16.6 years) suffering from ARDS of different aetiologies. INTERVENTIONS: Before and during each evaluation, the patients were kept under stable haemodynamic and metabolic conditions. The ventilatory setting was kept constant. All the patients were sedated, paralysed and mechanically ventilated. RESULTS: A statistically significant increase in the ratio between the arterial partial pressure of oxygen and fractional inspired oxygen (p < 0.01) was observed between the baseline conditions (mean 123.9 +/- 22.6) and VD (mean 153.0 +/- 16.9), while no statistical significant was noted between baseline conditions and after 10 min of restored DD (mean 141.1 +/- 19.7). A significant increase in Crs (p < 0.001) was observed between baseline conditions (mean 42 +/- 10.1) and VD (mean 48.8 +/- 9.6) and between baseline conditions and restored DD (mean 44.7 +/- 10.6). Two patients were considered nonresponders. All the patients were haemodynamically stable. No side effects were noted. CONCLUSIONS: We observed an increase in oxygenation and Crs when the patients were turned from the supine to the prone position with the upper thorax and pelvis supported.

Adult↗
PubMed1997

Pressure-volume curves in acute respiratory failure: automated low flow inflation versus occlusion.

Pressure-volume (P-V) curves of the respiratory system allow determination of compliance and lower and upper inflection points (LIP and UIP, respectively). To minimize lung trauma in mechanical ventilation the tidal volume should be limited to the P-V range between LIP and UIP. An automated low flow inflation (ALFI) technique, using a computer-controlled Servo Ventilator 900C, was compared with a more conventional technique using a series of about 20 different inflated volumes (Pst-V curve). The pressure in the distal lung (Pdist) was calculated by subtraction of resistive pressure drop in connecting tubes and airways. Compliance (Cdist), Pdist(LIP), and Pdist(UIP) were derived from the Pdist-V curve and compared with Cst, Pst(LIP), and Pst(UIP) derived from the Pst-V curve. Nineteen sedated, paralyzed patients (10 with ARDS and 9 with ARF) were studied. We found: Cdist = 2.3 + 0.98 x Cst ml/cm H2O (r = 0.98); Pdist(LIP) = 0.013 + 1.09 x Pst(LIP) cm H2O (r = 0.96). In patients with ARDS: Pdist(UIP) = 4.71 + 0.84 x Pst(UIP) cm H2O (r = 0.94). In ARF, we found differences in UIP between the methods, but discrepancies occurred above tidal volumes and had little practical importance. They may reflect that Pdist comprises dynamic phenomena contributing to pressure in the distal lung at large volumes. Compliance, but not LIP and UIP, could be accurately determined without subtraction of resistive pressure from the pressure measured in the ventilator. We conclude that ALFI, which is fully automated and needing no ventilator disconnection, gives useful clinical information.

Acute Disease↗
PubMed1997

Hexosaminidase in Trichinella spiralis is a single protein with alpha- and beta-subunits catalytic activities.

Beta-N-acetylhexosaminidase is expressed as a single protein in Trichinella spiralis and has catalytic properties similar to the alpha- and beta-subunits of human and mouse isoenzymes A and B. It can hydrolyze the artificial substrates, 4-methylumbelliferyl-beta-D-glucosamine and 4-methylumbelliferyl-beta-D-glucosamine-6-sulphate which are respectively hydrolyzed by the beta- and alpha-subunits. The enzyme is thermostable, has a basic isoelectric point, and thus is similar to the B isoenzyme. Northern blotting experiments indicate that the enzyme is encoded by a single gene. Hexosaminidase from Trichinella spiralis shows that the substrate specificities of alpha- and beta-subunits precede the duplication of their genes.

Animals↗
PubMed1996

Evaluation of brain perfusion with high resolution single photon emission tomography in the diagnosis of brain death.

Nuclear Medicine studies performed with tomographic acquisition and tracers such as Technetium-99m hexamethyl-propyleneamine oxime (99mTc-HMPAO) are able to assess cerebral blood flow. A case is reported of a patient with a large intracranial tumor, of possible pituitary origin, with a clinical and electroencephalographic suspicion of brain death. The patient had endocrinous-metabolic impairments for a history of impotence, since 18 months, and diabetes insipidus with a urine output of 350 ml/hr in the first 24 hours from the clinical suspicion of brain death. Due to the endocrinous-metabolic impairments, according to Italian law, it was necessary to confirm the diagnosis of brain death by performing a study able to assess cerebral blood flow. A single Photon Emission Tomography (SPET) scan was performed after the intravenous administration of 99mTc-HMPAO using a high resolution, brain dedicated device. No tracer uptake was evident in cerebral, cerebellar and brain stem structures. The cerebral blood flow study by SPET confirmed the diagnosis of brain death and made the organ transplant possible in a short period of time. High resolution SPET studies are useful to confirm the diagnosis of brain death when there are factors that can influence clinical and electroencephalographic signs, reducing time to authorise the organ explant.

Adult↗
PubMed1995

Titration of tidal volume and induced hypercapnia in acute respiratory distress syndrome.

Mechanical ventilation may promote overdistension-induced pulmonary lesions in patients with acute respiratory distress syndrome (ARDS). The static pressure-volume (P-V) curve of the respiratory system can be used to determine the lung volume and corresponding static airway pressure at which lung compliance begins to diminish (the upper inflection point, or UIP). This fall in compliance may indicate overdistension of lung units. We prospectively studied 42 patients receiving mechanical ventilation with an FIO2 of 0.5 or more for at least 24 h. According to the Lung Injury Score (LIS), 25 patients were classified as having ARDS (LIS > 2.5), while 17 patients constituted a non-ARDS control group. The P-V curve was obtained every 2 d. Mechanical ventilation initially used standard settings (volume-control mode, a positive end-expiratory pressure [PEEP] adjusted to the lower inflection point on the P-V curve, and a tidal volume [VT] of 10 ml/kg). The end-inspiratory plateau pressure (Pplat) was compared to the UIP, and VT was lowered when the Pplat was above the UIP. In the range of lung volume studied on the P-V curves (up to 1600 ml), a UIP could be shown in only one control patient (at 23 cm H2O). By contrast, a UIP was present on the P-V curve obtained from all patients with ARDS, corresponding to a mean airway pressure of 26 +/- 6 cm H2O, a lung volume of 850 +/- 200 ml above functional residual capacity and 610 +/- 235 ml above PEEP.(ABSTRACT TRUNCATED AT 250 WORDS)

Case-Control Studies↗
PubMed1995

Survival to lipopolysaccharide, cytokine release and phagocyte functions in mice treated with different total parenteral nutrition regimens.

Effects on host defenses of Total Parenteral Nutrition (TPN) with long- (LCT) and medium-chain triglycerides (MCT) were studied. Survival to lipopolysaccharide (LPS) challenge, blood clearance of Escherichia coli, in vivo and in vitro production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were investigated. In BALB/c mice, LCTs produced a 25% reduction in mortality, compared with controls. TPN performed with a LCT plus MCT mixture reduced mortality by 50%. Spasms appeared after 18 h and 12 h respectively in mice treated with LCT-MCT mixture or LCTs alone, respect to controls (8 h). The LCT-MCT mixture produced a 67% blood clearance of E. coli after 1 h, while the treatment with LCTs alone had no significant effects compared to controls (about 40%). The LCT-MCT mixture induced a 50% increase in chemiluminescence respect to controls. A 33% increase was observed in rats treated with LCTs alone. TNF-alpha serum levels after challenge with LPS were not modified by any of the triglycerides or their combinations. IL-6 increased by 43% with LCT-MCT mixture and by 39% with LCTs alone versus controls. After a 3 h in vitro treatment with LCTs, human monocytes were stimulated to release TNF-alpha at levels higher than those stimulated with the LCT-MCT mixture, and respect to controls. In contrast after 3 h the stimulation with LCT-MCT mixture induced a higher IL-6 release than controls and cells stimulated with LCTs alone, or with LPS.

Animals↗
PubMed1994

GM2 activator protein expression in mouse tissues.

The GM2 activator protein is an essential cofactor of hexosaminidase A in the degradation of GM2 ganglioside and it is responsible for the variant AB of GM2 gangliosidosis in man. In this study GM2 activator protein and its mRNA were determined in different mouse tissues. It was found that this protein is expressed mostly in the spleen and testis followed by brain and kidney which represent the main source in man. It is also interesting that in mouse testis there is a higher expression of the alpha subunit of hexosaminidase, thus suggesting a relationship between alpha subunit and GM2 activator protein. Furthermore the results indicate that the expression of GM2 activator protein is regulated, at least in part, at the transcriptional level.

Animals↗
PubMed1994

Different expression of beta-N-acetylhexosaminidase in mouse tissues.

The expression of genes encoding for the alpha and beta-subunits of the lysosomal enzyme beta-N-acetylhexosaminidase was investigated in different mouse tissues. It was found, using fluorogenic substrates, that the amounts of alpha and beta subunits were not the same in different tissues: alpha-subunit was more abundant in the brain, beta-subunit in epididymis and brain. The different isoenzyme patterns and specific activities in mouse tissues are due to the differences in the amount of hexosaminidase subunits. The mRNA, evaluated by Northern blotting analyses, revealed a greater expression of alpha-subunit in the testis and of beta-subunit in the brain and epididymis. The results indicate, therefore, that gene expression and the amount of subunits are in good relationship for beta-subunit, whereas there is no correlation for alpha-subunit.

Animals↗
PubMed1994

Changes in oncogene expression in ascite tumour cells during ageing.

The expression of two oncogenes, c-myc and c-fos, was studied in an ascitic tumour (ATPC+) at different times after implantation. The specific mRNA synthesis was analysed by Northern blot analysis. The presence of the oncogene proteins was shown by immunofluorescence using flow cytometry and referred to the distribution of the cells in the different cell phases. The results show that both oncogenes are expressed by ATPC+ tumour cells. c-myc is expressed 5, 8 and 12 days after implantation, although with a different intensity, and the protein is mainly present in S or S+G2 phase cells. The c-fos oncogene is expressed only 12 days after tumour implantation and the cells labelled with the specific antibody are mainly in G1 phase. We conclude that c-myc is principally correlated with proliferative activity, whereas c-fos is expressed by non-cycling cells.

Animals↗
PubMed1994

[Multiple organ failure in pre-term pregnancy: gestosis and/or typhoid fever?].

The authors describe a clinical case of Multiple Organ Failure (MOF). Such a pathology was reported, at admission in ICU, in a young woman aged 26 who was in the 30th week of amenorrhoea, formerly hospitalized in Obstetrics, where she had had a Caesarean section because of the met of eclamptic crisis, after a pregnancy substantially normal. At the moment of her admission to the ICU the examination highlighted the sense organ obnubilated, the breath dyspnoic, a systolic and diastolic hypotension and a tachycardia of medium seriousness. From laboratory examinations it was possible to maintain that there was a serious anemia with white cells raised, a coagulative imbalance and above all a serious alteration of hepatic and pancreatic function. The creatininemia had increased a bit, a clear contraction of diuresis was present and a considerable metabolic acidosis had become intelled. Therefore the patient was affected by multiple organ failure. In successive days it was possible to execute an EEG that proved substantially normal, then a Computer Tomography to abdomen showed the presence of vast areas of hepatic necrosis, ascitic hemorrhagic fluid and a volume increased pancreas. Hepatitis markers proved negative, while a positive response was achieved for a typhoid infection (this result was reconfirmed many times later.) Modifying the antibiotic therapy (substituting full dose ampicillin to the cephalosporin) the clinical case was solved. Moreover, also thanks to a very good answer to antibiotic therapy, it was possible to confirm the diagnosis of typhoid fever, not gestosis.

Adult↗
PubMed1992

Different expression of tyrosine aminotransferase and serine deydratase in rat livers after partial hepatectomy.

Tyrosine aminotransferase activity in rat liver increases during the first 24 hrs after partial hepatectomy with two peaks, one at 10 hrs and another at 18 hrs. This behaviour is due to an increase in TATmRNA synthesis. Expression of serine deydratase is also enhanced during the first 5 hrs after hepatectomy. It is suggested that the enhanced expression of the two genes is due to an increase in hormone incretion particularly glucagon and glucocorticoids.

Animals↗
PubMed1992

Anesthetic agents induce human mononuclear leucocytes to release cytokines.

Studies were carried out on the ability of some anesthetic agents (Propofol, Dormicum, Ketalar and Penthotal) to induce the release of cytokines by human monocytes and lymphocytes in vitro. All anesthetic agents tested at hematic concentrations reached during anesthetic administration cause an increase in the production of Tumor necrosis factor (TNF) from human monocytes; the increase is 4-5 times greater than controls. The greatest Interleukin -1 alpha (IL-1 alpha) production increase was induced by Propofol. The release of Interleukin -6 (IL-6) is notably increased by Ketalar (about 10 times greater than controls). In the presence of different anesthetic agents, human lymphocytes release Interleukin -4 (IL-4) and Interferon gamma- (IFN-gamma). Penthotal and Ketalar increase IL-4 production which appears quite high compared to that obtained with Con A used as standard challenge. Propofol induce IL-4 release which is about the same as that seen with Con A. IFN-gamma is released in high quantities by lymphocytes treated with Propofol. Dormicum, Ketalar and Penthotal induce non-significant increase of IFN-gamma release. The results concern the choice of anesthetic, in relation to its action on host immune response. This aspect is particularly interesting in immunocompromised host.

Anesthetics↗