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P Volpe

Publications and source records attributed to P Volpe.

At least 19 recordsLinked to original sources
PubMed2001

Targeting of calsequestrin to the sarcoplasmic reticulum of skeletal muscle upon deletion of its glycosylation site.

The glycoprotein calsequestrin (CS) is segregated to the junctional sarcoplasmic reticulum (jSR) and is responsible for intraluminal Ca(2+) binding. A chimeric CS-hemoagglutinin 1 (HA1), obtained by adding the nine amino acid viral epitope hemoagglutinin to the carboxy terminal of CS and shown to be correctly segregated to skeletal muscle jSR [A. Nori, K. A. Nadalini, A. Martini, R. Rizzuto, A. Villa, and P. Volpe (1997). Chimeric calsequestrin and its targeting to the junctional sarcoplasmic reticulum of skeletal muscle. Am. J. Physiol. 272, C1420-C1428] lends itself as a molecular tool to investigate the targeting domains of CS. A putative targeting mechanism of CS to jSR implies glycosylation-dependent steps in the endoplasmic reticulum (ER) and Golgi complex. To test this hypothesis, CS-HA1DeltaGly, a mutant in which the unique N-glycosylation site Asn316 was changed to Ile, was engineered by site-directed mutagenesis. The mutant cDNA was transiently transfected in either HeLa cells, myoblasts of rat skeletal muscle primary cultures, or regenerating soleus muscle fibers of adult rats. The expression and intracellular localization of CS-HA1DeltaGly was studied by double-labeling epifluorescence by means of antibodies against either CS, HA1, or the ryanodine receptor calcium release channel. CS-HA1DeltaGly was expressed and retained to ER and ER/sarcoplasmic reticulum of HeLa cells and myotubes, respectively, and expressed, sorted, and correctly segregated to jSR of regenerating soleus muscle fibers. Thus, the targeting mechanism of CS in vivo appears not to be affected by glycosylation-that is, the sorting, docking, and segregation of CS are independent of cotranslational and posttranslational glycosylation or glycosylations.

Animals↗
PubMed2000

Evidence for the presence of two homer 1 transcripts in skeletal and cardiac muscles.

A family of proteins, Homers 1, 2 and 3, involved in activity-dependent control of signal transduction has been recently described in neurons [Xiao, B., Tu, C. J., Petralia, R. S., Yuan, J. P., Doan, A., Breder, C. D., Ruggiero, A., Lanahan, A. A., Wenthold, R. J., and Worley, P. F. (1998) Homer regulates the association of group 1 metabotropic glutamate receptors with multivalent complexes of Homer-related, synaptic proteins. Neuron 21, 707-716]. By RT-PCR and RNasePA, mRNAs transcripts for Homer 1a and Homer 1c, but not Homer 1b, are detected in both skeletal and cardiac muscles of the rat. Full-length cloning of Homer 1a and Homer 1c cDNAs has been accomplished: There is no tissue specificity, by comparing skeletal muscle, cardiac muscle and cerebellum, and there are a few species-specific base substitutions, by comparing rat and mouse sequences. The regulatory mechanism exerted via transition of Homer 1 isoform composition may be operative in striated muscles.

Animals↗
PubMed2000

Site-directed mutagenesis and deletion of three phosphorylation sites of calsequestrin of skeletal muscle sarcoplasmic reticulum. Effects on intracellular targeting.

Calsequestrin (CS) is segregated to the junctional sarcoplasmic reticulum (jSR) of skeletal muscle fibers and is responsible for intraluminal Ca(2+) binding. A chimeric CS-HA1, obtained by adding the nine-amino-acid viral epitope hemagglutinin (HA1) to the carboxy-terminal of CS and shown to be correctly segregated to skeletal muscle jSR in vivo (A. Nori, K. A. Nadalini, A. Martini, R. Rizzuto, A. Villa, and P. Volpe, 1997, Am. J. Physiol. 272, C1420-C1428), is mutagenized in order to identify domains of CS involved in targeting. Since a putative targeting mechanism of CS implies phosphorylation-dependent steps in the endoplasmic reticulum (ER) and/or Golgi complex, five CS-HA1 mutants disrupting the three phosphorylation sites of CS (Thr(189), Thr(229), and Thr(353)) were engineered by either site-directed mutagenesis or deletion: CS-HA1DeltaP1 (Thr(189) --> Ile); CS-HA1DeltaP2 (Thr(229) --> Asn); CS-HA1DeltaP1,2; in which Thr(189) and Thr(229) were changed to Ile and Asn, respectively; and CS-HA1Delta14(COOH) and CS-HA1Delta49 (COOH), in which 14 residues (Glu(354)-Asp(367)) and 49 residues (Asp(319)-Asp(367)), respectively, were deleted at the carboxy-terminal. Mutant cDNAs were transiently transfected in either HeLa cells, cultured myoblasts of rat skeletal muscle, or regenerating soleus muscle fibers of adult rats. Each CS-HA1 mutant was identified by Western blot as a single polypeptide of the predicted molecular weight. The intracellular localization of CS-HA1 mutants was studied by immunofluorescence using specific antibodies against either CS or HA1. CS-HA1 mutants colocalized with ER markers, e.g., calreticulin, and partially overlapped with Golgi complex markers, e.g., alpha-mannosidase II, in HeLa cells and myotubes. CS-HA1 mutants were expressed and retained in ER and ER/SR of HeLa cells and myotubes, respectively, and correctly segregated to jSR of regenerating soleus muscle fibers. Thus, the targeting mechanism of CS in vivo is not affected by phosphorylation(s); i.e., sorting and segregation of CS appear to be independent of posttranslational phosphorylation(s).

Animals↗
PubMed2000

Unintentional ileostomy: a complication of the videolaparoscopic method? Report of the first case.

Jejunostomy is widely acknowledged in the literature as a means for enteral nutrition. Complication rates range from 16% to 46% for the classical open technique and from 11% to 70% for the several mini-invasive techniques currently in use, including the laparoscopic techniques. The most probable complications are abscess, intestinal obstruction, abdominal wall infection, intraperitoneal leakage, enterocutaneous fistula, and loss, elbowing, or even rupture of the enteral probe. The authors report the case of a patient with severe malnutrition concomitant with advanced gastric cancer who underwent jejunostomy because of an incapacity for normal oral feeding. Previous attempts to pass a nasal enteral probe were not successful, even with the aid of endoscopy. Videolaparoscopy was indicated for adequate staging of the neoplasm and for performance of video-assisted jejunostomy. During the procedure, an extensive carcinomatous process was observed that rendered comprehension of the abdominal anatomy extremely difficult. Consequently, while attempting jejunal catheterization, unintentional catheterization of the terminal ileum took place. The authors discuss this first reported case of unintentional ileostomy and review the literature.

Aged↗
PubMed1999

Magnetic fields increase cell survival by inhibiting apoptosis via modulation of Ca2+ influx.

Static magnetic fields with intensities starting from 6 gauss (6x10(-4) tesla, T) were found to decrease in an intensity-dependent fashion, reaching a plateau at 6 x 10(-3) T, the extent of cell death by apoptosis induced by several agents in different human cell systems. This is not due to a change in the mode of cell death (i.e., to necrosis) or to a delay of the process itself; rather, the presence of magnetic fields allows the indefinite survival and replication of the cells hit by apoptogenic agents. The protective effect was found to be mediated by the ability of the fields to enhance Ca2+ influx from the extracellular medium; accordingly, it was limited to those cell systems where Ca2+ influx was shown to have an antiapoptotic effect. Magnetic fields thus might interfere with human health by altering/restoring the equilibrium between cell death and proliferation; indeed, the rescue of damaged cells may be the mechanism explaining why magnetic fields that are not mutagenic per se are often able to increase mutation and tumor frequencies.

Animals↗
PubMed1999

Targeting of calsequestrin to sarcoplasmic reticulum after deletions of its acidic carboxy terminus.

Calsequestrin (CS) is the Ca(2+) binding protein of the junctional sarcoplasmic reticulum (jSR) lumen. Recently, a chimeric CS-HA1, obtained by adding the nine-amino-acid viral epitope hemagglutinin (HA1) to the COOH terminus of CS, was shown to be correctly segregated to the sarcoplasmic reticulum [A. Nori, K. A. Nadalini, A. Martini, R. Rizzuto, A. Villa, and P. Volpe. Am. J. Physiol. 272 (Cell Physiol. 41): C1420-C1428, 1997]. A putative targeting mechanism of CS to jSR implies electrostatic interactions between negative charges on CS and positive charges on intraluminal domains of jSR integral proteins, such as triadin and junctin. To test this hypothesis, 2 deletion mutants of chimeric CS were engineered: CS-HA1DeltaGlu-Asp, in which the 14 acidic residues [-Glu-(Asp)(5)-Glu-(Asp)(7)-] of the COOH-terminal tail were removed, and CS-HA1Delta49(COOH), in which the last, mostly acidic, 49 residues of the COOH terminus were removed. Both mutant cDNAs were transiently transfected in HeLa cells, myoblasts of rat skeletal muscle primary cultures, or regenerating soleus muscle fibers of adult rats. The expression and intracellular localization of CS-HA1 mutants were studied by epifluorescence microscopy with use of antibodies against CS or HA1. CS-HA1 mutants were shown to be expressed, sorted, and correctly segregated to jSR. Thus short or long deletions of the COOH-terminal acidic tail do not influence the targeting mechanism of CS.

Acids↗
PubMed1998

Cell membrane lipid molecular dynamics in a solenoid versus a magnetically shielded room.

The generalized polarization function of the fluorescent probe 2-dimethylamino-6-lauroylnaphthalene has been used to evaluate the lipid dynamics in Friend erythroleukemia cell membrane. The values of this function varied during the culture growth cycle, showing decreased lipid dynamics 24-48 h from the cell seeding. When the cycle occurred in a solenoid producing a magnetic field of 70 microT at 50 Hz in addition to the 45 microT DC of the earth (short-term 4-day exposure), the membrane lipid dynamics during this same time-period decreased by about 10% (P < .04). After long-term (184 days) or extremely long-term (395 days) exposure of the cells to the magnetic field, little additional variation in the membrane lipid dynamics was observed, suggesting an adaptation phenomenon. A variation of membrane lipid dynamics was also observed due to in vitro cell differentiation (P < .02). Nevertheless, the exposure of both undifferentiating and differentiating cells to a highly attenuated magnetic field in a magnetically shielded room (20 nT DC plus 2.5 pT AC) did not induce any modification of membrane lipid dynamics.

Animals↗
PubMed1998

Kinetic basis of quantal calcium release from intracellular calcium stores.

The kinetics of Ca2+ release from canine cerebellum and rabbit skeletal muscle microsomes, mediated by the inositol 1,4,5-trisphosphate (IP3) receptor (IRC) and the ryanodine receptor (RyRC), respectively, were analyzed by a model, which considers that Ca2+ release channels undergo spontaneous inactivation. We found that: (i) both the initial rate of release (Vo) and the rate of inactivation (Vi) were saturable functions of the activating ligand concentration (CL); and (ii) the ratio of Vi/Vo, termed the relative tendency for inactivation, decreased with increasing CL. Equilibrium [3H]-IP3 binding studies, on the other hand, revealed the presence of one single class of non-co-operative IP3 sites in cerebellum membranes (Kdeq = 47 nM and Hill coefficient = 1.1). Based on the above Vi-Vo relationship and the IP3-binding data, we propose that quantal Ca2+ release through IRCs might be a result of spontaneous channel inactivation, whose rate is controlled by the ratio of IP3-occupied/free monomers in the tetrameric release channel units. Furthermore, because of the kinetic similarities between the IRC- and RyRC-mediated Ca2+ release processes, as well as between quantal Ca2+ release and channel adaptation, the same mechanism is also proposed to apply to the RyRC-mediated Ca2+ release as well as to constitute the basis of release channel adaptation.

Adenosine Triphosphate↗
PubMed1998

Laparoscopic treatment of traumatic diaphragmatic hernia.

Traumatic diaphragmatic hernia is rare, but is of utmost importance due to its high morbidity and mortality. It is markedly important in patients with blunt abdominal trauma, and diagnosis is difficult because of the numerous associated injuries. A patient with few symptoms of chronic traumatic diaphragmatic hernia is described, who underwent surgery due to a gastric volvulus. Laparoscopic surgery permits repair of these injuries through an abdominal approach, avoiding a thoracic incision or selective intubation.

Adolescent↗
PubMed1998

Measles virus spread and pathogenesis in genetically modified mice.

Attenuated Edmonston measles virus (MV-Edm) is not pathogenic in standard mice. We show here that MV-Edm inoculated via the natural respiratory route has a limited propagation in the lungs of mice with a targeted mutation inactivating the alpha/beta interferon receptor. A high dose of MV-Edm administered intracerebrally is lethal for about half of these mice. To study the consequences of the availability of a high-affinity receptor for MV propagation, we generated alpha/beta interferon-defective mice expressing human CD46 with human-like tissue specificity. Intranasal infection of these mice with MV-Edm resulted in enhanced spread to the lungs and more prominent inflammatory response. Virus replication was also detected in peripheral blood mononuclear cells, the spleen, and the liver. Moreover, intracerebral inoculation of adult animals with low MV-Edm doses caused encephalitis with almost inevitably lethal outcome. We conclude that in mice alpha/beta interferon controls MV infection and that a high-affinity receptor facilitates, but is not strictly required for, MV spread and pathogenesis.

Animals↗
PubMed1998

Omental flap obtained by laparoscopic surgery for reconstruction of the chest wall.

The reconstruction of complex defects of the chest wall after infection of the sternotomy wound presents a great challenge. Various options have been described for these reconstructions using muscle and omental flaps to fill the space and cover the defect. A case of reconstruction of a large defect of the chest cage and abdominal wall in a 62-year-old patient is presented. After surgery for revascularization of the myocardium, the patient developed mediastinitis, osteomyelitis, and necrosis of the sternum. The pectoralis major muscle was utilized for the reconstruction, but total loss of the flap occurred. After débridement, an omental flap obtained by laparoscopy was employed based on the left gastroepiploic artery. The omentum was transposed without complications through the abdominal wall defect. An overlay skin graft with the omentum as receptor bed completed the closure. There are advantages in using minimally invasive videolaparoscopy compared with laparotomy in obtaining the omentum, with the same result regarding reconstruction of the defect.

Humans↗
PubMed1998

Atypical cilia in the oviductal epithelium of healthy dogs.

Specimens of the uterine tube (ampulla) were obtained from seven healthy, ovario-hysterectomized dogs. Ultrastructurally, a total of 35,000 cilia were examined. Compound cilia ranged from 0.0 to 0.4%; both intracytoplasmic and swollen cilia ranged from 0.1% to 0.4%. The microtubular pattern was studied in 3,500 cross-sectioned cilia and an abnormal pattern was found in 2-5%. Similarly to the other animal species, abnormalities involving the peripheral microtubules were the prevailing defect. An electron-dense plug into the lumen was seen in 1-3% of the basal bodies; occasionally an abnormal spatial configuration of them was also observed. The incidence of abnormal cilia hence is lower than found in the tracheae.

Animals↗
PubMed1997

Fatty acyl-CoA-acyl-CoA-binding protein complexes activate the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum.

We previously reported that fatty acyl-CoA esters activate ryanodine receptor/Ca2+ release channels in a terminal cisternae fraction from rabbit skeletal muscle [Fulceri, Nori, Gamberucci, Volpe, Giunti and Benedetti (1994) Cell Calcium 15, 109-116]. Skeletal muscle cytosol contains a high-affinity fatty acyl-CoA-binding protein (ACBP) [Knudsen, Hojrup, Hansen, H.O., Hansen, H.F. and Roepstorff (1989) Biochem. J. 262, 513-519]. We show here that palmitoyl-CoA (PCoA) in a complex with a molar excess of bovine ACBP causes a discrete Ca2+ efflux or allows Ca2+ release from the Ca2+-preloaded terminal cisternae fraction by sub-optimal caffeine concentrations. Both effects were abolished by elevating the free [Mg2+] in the system, which inhibits the Ca2+ release channel activity. Sensitization towards caffeine was a function of both the concentration of the complex and the [PCoA]-to-[ACBP] ratio. In all experimental conditions the calculated free [PCoA] was no more than 50 nM, and such concentrations by themselves were inactive on Ca2+ release channels. The KD for PCoA binding was approx. 2 nM for bovine and yeast ACBP, and slightly higher (8 nM) for rat ACBP. The PCoA-rat ACBP complex behaved in the same manner as the PCoA-bovine ACBP complex, whereas the ester complexed with yeast ACBP was more active in activating/sensitizing Ca2+ efflux. A non-hydrolysable analogue of PCoA bound to (bovine) ACBP also sensitized the Ca2+ release channel towards caffeine. These findings indicate that fatty acyl-CoA-ACBP complexes either interact directly with one or more components in the terminal cisternae membranes or, through interaction with the component(s), donate the fatty acyl-CoA esters to high-affinity binding sites of the membrane, thus affecting (and possibly regulating) Ca2+ release channel activity.

Acyl Coenzyme A↗
PubMed1997

Cell-cycle kinetics of Friend erythroleukemia cells in a magnetically shielded room and in a low-frequency/low-intensity magnetic field.

This work was undertaken to compare the behavior of Friend erythroleukemia cells in a solenoid, where the magnetic field was 70 microT at 50 Hz (plus 45 microT DC of Earth) with that of the same cells in a magnetically shielded room, where the magnetic field was attenuated to 20 nT DC and 2.5 pT AC. The control laboratory magnetic field corresponded to 45 microT DC and a stray 50 Hz field below 0.2 microT. The culture growth cycle of cells maintained inside the solenoid was slightly accelerated compared with that of cells maintained outside the solenoid (P < .05). This stimulation probably depended on sensitivity of cell cycle to a magnetic field, because, inside the solenoid, the percentage of G1 cells slightly increased during the culture growth cycle, whereas that of S cells slightly decreased. Acceleration of growth was detected soon after exposure of the cultures to the solenoid field, and growth did not change further if the action of this field continued for a long time, accounting for adaptation. The solenoid field also caused a small increase of cell survival without influencing cell volume. By contrast, the culture growth cycle of cells maintained inside the magnetically shielded room was slightly decelerated compared with that of cells maintained outside the room (P < .05). The essential absence of any field inside the magnetically shielded room also caused a small increase of cell volume, whereas, during the culture growth cycle, the percentage of G1 cells decreased, and that of S cells increased. The majority of these events did not change in cells induced to differentiate hemoglobin through dimethylsulfoxide.

Animals↗
PubMed1997

Ondansetron dose response curve in high-risk pediatric patients.

STUDY OBJECTIVE: To establish a dose-response relationship for ondansetron, and to evaluate any effects of oral premedication with metoclopramide in pediatric patients undergoing tonsillectomy and adenoidectomy and strabismus surgery. DESIGN: Prospective, randomized, double blind study. SETTING: University affiliated, 280-bed pediatric hospital. PATIENTS: 320 ASA physical status l and II patients between the ages of 2 and 12 years undergoing tonsillectomy and adenoidectomy or strabismus surgery. INTERVENTIONS: Patients were randomized to eight investigational groups. Patients in all eight groups underwent a standard anesthetic. Groups 1, 2, 3, and 4 received intravenous (i.v.) saline or i.v. ondansetron at doses of 0.05 mg/kg, 0.1 mg/kg and 0.15 mg/kg, respectively. Groups 5, 6, 7, and 8 received oral metoclopramide 0.15 mg/kg as well as i.v. saline, and ondansetron 0.05 mg/kg, 0.1 mg/kg, or 0.15 mg/kg. Patients were evaluated for emetic episodes prior to and following discharge. MEASUREMENTS AND MAIN RESULTS: All doses of ondansetron 0.05 mg/kg, 0.1 mg/kg, and 0.15 mg/kg were significantly more effective than placebo in reducing the incidence of emesis prior to, following discharge, and during the first 24 postoperative hours (p < 0.001). There were no significant differences in the occurrence of emesis between the groups receiving ondansetron 0.05 mg/kg, 0.1 mg/kg, and 0.15 mg/kg. The addition of oral metoclopramide 0.15 mg/kg had no effect on the incidence of emesis in the ondansetron or placebo study groups. CONCLUSIONS: Ondansetron is an effective medication for the treatment and prevention of postoperative nausea and vomiting, and a dose of ondansetron 0.05 mg/kg is as effective as 0.1 mg/kg and 0.15 mg/kg. Metoclopramide 0.15 mg/kg has no effect on the incidence of postoperative nausea and vomiting.

Adenoidectomy↗
PubMed1997

Caudal epidural butorphanol plus bupivacaine versus bupivacaine in pediatric outpatient genitourinary procedures.

STUDY OBJECTIVE: To investigate the efficacy of adding butorphanol to bupivacaine administered in the caudal epidural space in children undergoing genitourinary (GU) procedures. DESIGN: Randomized, double-blinded, controlled study. SETTING: University affiliated pediatric hospital. PATIENTS: 200 ASA physical status I and II male patients between 6 months and 10 years of age. INTERVENTIONS: Patients were randomized to receive either 0.25% bupivacaine with 1:200,000 epinephrine alone (Group 1) or 0.25% bupivacaine with 1:200,000 epinephrine plus 30 micrograms/kg butorphanol (Group 2) administered via the caudal epidural space prior to surgical incision. MEASUREMENTS AND MAIN RESULTS: Patients were evaluated postoperatively until discharge. Measurements included requirement of additional analgesic, sedation, pain/ comfort scores, and a 24-hour analgesic follow-up. Significantly fewer patients in the butorphanol group required rescue morphine sulfate in the postanesthesia care unit (p < or = 0.001). The total number of morphine doses administered to Group 2 was significantly less than Group 1 (p < or = 0.001). 52% of patients in Group 1 compared with 28% in Group 2 required administration of additional analgesics following discharge from the hospital (p < or = 0.003), with 23% of Group 1 requiring a codeine compound compared with 8% in Group 2 (p < 0.03). CONCLUSIONS: The addition of 30 micrograms/kg butorphanol to 0.25% bupivacaine with epinephrine via the caudal epidural space is a safe, effective means to increase duration of analgesia following GU procedures.

Ambulatory Surgical Procedures↗
PubMed1997

Chimeric calsequestrin and its targeting to the junctional sarcoplasmic reticulum of skeletal muscle.

Calsequestrin (CS) is the junctional sarcoplasmic reticulum (jSR) Ca2+ binding protein responsible for intraluminal Ca2+ storage. The targeting mechanisms of CS to the jSR are yet to be unraveled. The nine-amino acid epitope of the influenza virus hemoagglutinin (referred to as HA1) was added at the COOH-terminal of CS by polymerase chain reaction cloning. The HA1-tagged CS cDNA was transiently transfected in either HeLa cells, myogenic cell lines, such as C2 and L8 cells, myoblasts of rat skeletal muscle primary cultures, or regenerating soleus muscle fibers of adult rats. The expression and intracellular localization of chimeric CS-HA1 were monitored by epifluorescence and confocal microscopy using either anti-CS antibodies or anti-HA1 antibodies. About 30% of transfected HeLa cells and 20-40% of myogenic cells expressed CS-HA1 into intracellular compartments, such as the perinuclear cisternae of endoplasmic reticulum (ER). Myoblasts of newborn rat skeletal muscles were first transfected and subsequently stimulated to differentiate into myotubes. CS-HA1 was detected in approximately 20% of transfected myotubes and did not affect CS distribution in myotubes. In the soleus muscle of adult rat, intramuscular injection of bupivacaine induced necrosis followed by regeneration. In vivo transfection of HA1-tagged CS cDNA in regenerating skeletal muscles determined expression in a few skeletal muscle fibers; CS-HA1 was localized only in jSR, as judged by confocal microscopy of longitudinal sections. The present results show that chimeric CS-HA1 is correctly sorted to ER/SR compartments and that the free COOH-terminal is not requested for sorting, retention, and segregation of CS to the SR.

Animals↗