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Biomedical subjects

P Volpe

Publications and source records attributed to P Volpe.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1997

[Xanthine urinary calculus in a patient with Lesch-Nyhan syndrome. Apropos of a case].

The authors report a case of xanthine stones in a 12-year-old child with Lesh Nyhan syndrome treated by allopurinol at the dose of 10 mg/kg/24 hours. This type of urinary stone is unusual and its structure was confirmed by spectrophotometric analysis. This type of stone, in the context of Lesh Nyhan syndrome, suggests the presence of allopurinol treatment. Discontinuation of this treatment prevents recurrence of xanthine stones.

Allopurinol↗
PubMed1996

Topical lidocaine for postoperative analgesia following myringotomy and tube placement.

One of the most frequently performed surgical procedures in pediatrics is myringotomy and tube placement. Analgesia is often difficult to achieve and children may be uncontrollable, distressing both parents and nursing staff. We designed this investigation to determine if topical lidocaine instilled in the ear canal after myringotomy and tube placement could improve postoperative analgesia. This prospective, randomized, double-blind clinical trial compared topical 4% lidocaine combined with antibiotic drops to placebo and antibiotic drops placed in the external auditory canal following completion of myringotomy and tube placement. One hundred twenty-two ASA class I or II patients were enrolled and completed this investigation. Primary outcome measure was relief of pain based on pain scores and the need for acetaminophen. Patients who received 4% lidocaine with gentamicin had better pain scores (2.81; P = 0.002) than those receiving placebo (4.77). Twenty-seven patients (45%) in the control group received acetaminophen for treatment of postoperative pain compared to eight (13%) in the lidocaine group (P < 0.001). No reports or complaints of vertigo or tinnitus were noted in any patient. The application of 4% lidocaine in antibiotic drops significantly improves postoperative analgesia in patients undergoing myringotomy and tube insertion under general anesthesia. Utilizing this technique should help improve analgesia, specifically in the early postoperative period, and decrease the presence of stress following surgery.

Administration, Topical↗
PubMed1996

Biochemical and functional heterogeneity of rat cerebrum microsomal membranes in relation to SERCA Ca(2+)-ATPases and Ca2+ release channels.

Rat cerebrum microsomes were subfractionated on isopycnic linear sucrose (20-42%) density gradients. The Ca2+ loading/release properties and the distribution of intracellular Ca2+ store channels, inositol 1,4,5-trisphosphate (IP3) receptor and ryanodine (Ry) receptor, and SERCA pumps, were monitored in each subfraction by ligand binding and 45Ca2+ loading/release assays. Three different classes of vesicles were identified: (i) heavy density vesicles with high content of Ry receptors and Ca2+ pumps and high thapsigargin (TG)-sensitivity of Ca2+ loading; (ii) intermediate sucrose density vesicles with high content of IP3 receptor, high IP(S)3-sensitivity of Ca2+ loading and low content of Ry receptors; and (iii) light sucrose density vesicles with high content of Ry receptors, low content of IP3 receptors and low content of SERCA pumps highly sensitive to TG. Isolation of molecularly heterogeneous rat cerebrum microsomes and identification of specific Ca2+ loading/release properties support the presence of multiple, potentially active, heterogeneous rapidly exchanging Ca2+ stores in rat cerebrum.

Animals↗
PubMed1996

Retroperitoneal laparoscopic nephrectomy in children. Preliminary report of 18 cases.

Laparoscopic nephrectomy is a new procedure which remains to be evaluated in adults and children. This technique enables the reduction of parietal complications and sequelae. The majority of indications, e.g. renal dysplasia, destroyed kidneys due to obstructive or refluxing uropathy, are suitable for laparoscopic nephrectomy. Contraindications are Wilm's tumor and trauma which represent only 20% of nephrectomies in our experience. As in open surgery, a retroperitoneal approach seems more logical and better adapted than a transperitoneal approach to perform nephroureterectomy for benign disease. From August 1993 to December 1995, we attempted 18 retroperitoneal laparoscopic nephrectomies in children aged from 3 months to 14 years. The patient is placed in a lateral position, and after creation of a retropneumoperitoneum under direct vision control without balloon dissection, three or four ports are needed, renal vessels are dissected, then clipped or coagulated if small. Destroyed kidneys are generally of small size, so they can be extracted via a 10- or 12-mm cannula site without morcellation. Operative time is 35-210 min (median 106 min). There were no major complications and only one conversion. In conclusion, retroperitoneal laparoscopic nephrectomy in children is a feasible and safe procedure in well-trained hands.

Adolescent↗
PubMed1996

Autotransfusion with laparoscopically salvaged blood in trauma: report on 21 cases.

Autotransfusion is being increasingly used to avoid the complications of homologous blood transfusion. In abdominal trauma, however, the collected blood may be contaminated by intestinal contents when digestive or urinary lesions are present. In such situations, the reinfusion of blood is contraindicated. We present our experience with autotransfusion of blood collected by laparoscopy from the abdominal cavity of 21 trauma patients. Laparoscopy allowed the aspiration of blood and, at the same time, permitted diagnosis of visceral lesions, avoiding reinfusion of contaminated blood. No complications occurred, and hematocrit values were significantly elevated. This procedure may represent the only possible method of blood transfusion in Jehovah's Witnesses, as with one patient in our series.

Abdominal Injuries↗
PubMed1996

Retroperitoneal laparoscopic nephrectomy in children: preliminary report of six cases.

Laparoscopic nephrectomy is a new procedure that must be evaluated in adults and children. This technique allows a reduction in complications and sequelae. The majority of indications, such as renal dysplasia and destroyed kidneys due to obstructive or refluxing uropathy, are suitable for laparoscopic nephrectomy. Contraindications are Wilms' tumor and trauma, which represent only 20 percent of nephrectomies in our experience. As in open surgery, to perform nephroureterectomy for benign disease, a retroperitoneal approach seems more logical than transperitoneal approach, which is the usual approach for laparoscopic surgeons. We have attempted six retroperitoneal laparoscopic nephrectomies in children from 3 months to 14 years old. The patient is positioned in a lateral position after creation of a retropneumoperitoneum under visual control; three or four ports are needed and renal vessels are dissected then clipped, or coagulated if small. Destroyed kidneys are generally of small size, so they can be extracted via a 10- or 12-mm cannula site without morcellation. Operative time ranges from 35 to 210 mm (median 120 mm). We have had no complications or conversions. Retroperitoneal laparoscopic nephrectomy in children is a feasible and safe procedure in well-trained hands.

Adolescent↗
PubMed1995

LU52396, an inhibitor of the store-dependent (capacitative) Ca2+ influx.

The effects of 1-[2-(4-fluorophenyl)cyclohexyl]-2-[4-(3-phenylalkyl)-piperazin -1-yl]- ethanol, LU52396, on a) Ca2+ influx across the plasma membrane and b) Ca2+ mobilization from intracellular rapidly-exchanging Ca2+ stores were investigated in HeLa cells and in isolated microsomal fractions derived from the cerebellum and the skeletal muscle. LU52396 was found to be a potent inhibitor (Ki of about 2 microM) of the Ca2+ influx activated by depletion of intracellular Ca2+ stores, a phenomenon referred to as store-dependent or capacitative Ca2+ influx. Such an effect, which was reversed by cell washing, was mediated neither by a depolarization of the cell, with decrease in the driving force for cation influx, nor by a change of the intracellular pH, and might therefore be due to a direct action of the drug on either the responsible channel in the plasma membrane or, less likely, on its regulatory mechanisms. Additional effects, i.e. inhibition of receptor-mediated Ca2+ influx, of Ca2+ release from intracellular stores via either inositol 1,4,5-trisphosphate or ryanodine receptors, and of Ca2+ reuptake into the stores via sarcoplasmic-endoplasmic reticulum Ca(2+)-ATPases, were also induced by the drug, however at concentrations 20-fold or more than those effective on the store-dependent influx. To our knowledge LU52396 is the first pharmacological tool that is found to be addressed with some preference to the store-dependent Ca2+ influx. It promises, therefore, to be useful for the characterization of the process, the identification of the responsible channel and, possibly, also of the molecular mechanisms through which these channels operate.

Animals↗
PubMed1995

Intracellular Ca2+ stores in chick cerebellum Purkinje neurons: ontogenetic and functional studies.

The molecular composition of intracellular Ca2+ stores in developing chicken cerebellum Purkinje neurons from embryonic day 11 (E11) to posthatching day 2 (P2) was studied by immunocytochemistry using specific antibodies for three molecular constituents, the receptor (R) and/or channel sensitive to inositol 1,4,5-trisphosphate (IP3), Ca(2+)-adenosinetriphosphatase (ATPase), and calsequestrin (CS). CS, IP3R, and Ca(2+)-ATPase were first detected by light-microscopic immunofluorescence in migrating Purkinje cells at E11-E12 and throughout late phases of embryonic development. Ontogenesis of CS, IP3R, and Ca(2+)-ATPase accompanied well-defined stages of cerebellum histogenesis and cytogenesis and was accomplished before hatching. High-resolution immunogold electronmicroscopy revealed that, at E18-P1, CS was still largely distributed to the endoplasmic reticulum (ER) lumen and began to be segregated to ER subcompartments (calciosomes) only by P2, whereas the IP3R was concentrated into ER cisternal stacks as early as E18. Both ionotropic and metabotropic plasma membrane receptors were present in dissociated single chicken Purkinje cells from E16 onward, as indicated by measurements of membrane currents (whole cell recording mode) and of cytoplasmic Ca2+ transients monitored with the cell-trappable fluorescent indicator fura 2-acetoxymethyl ester, respectively. Cytoplasmic Ca2+ transients were detected after either activation of glutamate metabotropic receptors, i.e., evidence of IP3-sensitive Ca2+ channels, or application of caffeine, i.e., evidence of ryanodine-sensitive Ca2+ channels. Intracellular Ca2+ stores appear to be functional during embryonic development.

Aging↗
PubMed1995

[Predictive value of urinary cytology in the diagnosis of urothelial tumors].

Between November 1991 and June 1993, 315 patients with urethral lesions were divided into two groups: group 1 included 215 patients with urethral tumours and group 2 included 100 patients with non-tumoural lesions. In all patients, urethral smears (performed on 3 consecutive days), pyelography and uretrocystoscopy (with bladder biopsy of observable lesions) were performed in all. The sensitivity of urine cytology examinations in the diagnosis of bladder cancer was found to by 80% with a specificity of 90%. The positive predictive value was 94.5% and the negative predictive value 67.7%. Urine cytology agreed with the diagnosis of urethral tumours especially well in advanced stage ulcerated tumours. These results underline the importance of cytology examinations in the exploration and follow-up of patients with urethral tumours.

Adult↗
PubMed1994

Calstorin, a new Ca2+ binding protein of the microsome lumen which is abundant in the rat brain.

A new Ca2+ binding protein (apparent Mr: 54 KDa; pI: 4.37; Stains All positive) which, based on N terminal sequence and immunological criteria, appears different from calsequestrin, calreticulin and the chaperonins, has been identified in the rat brain and recovered primarily in the microsome fraction. Carbonate extraction and trypsin digestion experiments suggest the protein to be located within the microsome lumen. Its expression levels are considerable especially in the cerebellum (65% with respect to calreticulin). 45Ca binding experiments on 2D blots suggest the protein to be of high capacity (higher than calreticulin) and low affinity (apparent Kd: 3 mM). These properties are typical of the proteins participating in the storage of Ca2+ within rapidly exchanging organelles. The tentative name of calstorin (calcium-storage-protein, CST) is therefore proposed.

Amino Acid Sequence↗
PubMed1994

Calsequestrin is a component of smooth muscles: the skeletal- and cardiac-muscle isoforms are both present, although in highly variable amounts and ratios.

Expression by smooth-muscle cells of calsequestrin (CS), the low-affinity/high-capacity Ca(2+)-binding protein of striated-muscle sarcoplasmic reticulum (SR), has been investigated in recent years with conflicting results. Here we report the purification and characterization from rat vas deferens of two CS isoforms, the first deemed skeletal muscle, the second cardiac type, on account of their N-terminal amino acids and other relevant biochemical and molecular properties. Compared with vas deferens, the smooth muscles from aorta and stomach, in that order, were found to express lower amounts of CS, whereas in the uterus and bladder the protein was not detectable. The ratio between the two CS isoforms was also variable, with the stomach and aorta predominantly expressing the skeletal-muscle type and the vas deferens expressing the two CSs in roughly similar amount. Because of the property of CSs to localize within the skeletal-muscle SR lumen not uniformly, but according to the distribution of their anchorage membrane proteins, the expression of the protein suggests the existence in smooth-muscle cells of discrete endoplasmic-reticulum areas specialized in the rapidly exchanging Ca2+ storage and release, and thus in the control of a variety of functions, including smooth-muscle contraction.

Amino Acid Sequence↗
PubMed1994

Fatty acyl-CoA esters induce calcium release from terminal cisternae of skeletal muscle.

The effect of palmitoyl-CoA (PCoA) on Ca2+ fluxes in unfractionated SR, longitudinal tubules (LSR) and terminal cisternae (TC) subfractions, obtained from rabbit fast-twitch skeletal muscles, was investigated. After MgATP-dependent Ca2+ preloading, PCoA released Ca2+ from unfractionated SR and TC, but not from LSR. Both the extent and the rate of PCoA-induced Ca2+ release from TC were increased in a dose-dependent manner, the half-maximal effect being attained at [PCoA] of approximately 6 microM. Ruthenium red, a Ca2+ release channel blocker, completely inhibited PCoA-induced Ca2+ release, whereas caffeine, a Ca2+ release channel agonist, depleted TC of Ca2+ and prevented the PCoA action. Scatchard plot analysis of [3H]-ryanodine binding showed that PCoA increased the affinity without affecting Bmax. The action of PCoA was mimicked by a nonhydrolysable analog. The present results indicate that PCoA interacts and opens the Ca2+ release channel (ryanodine receptor) of TC and that the mechanism of action involves binding rather than hydrolysis.

Acyl Coenzyme A↗