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Biomedical subjects

R Orlando

Publications and source records attributed to R Orlando.

At least 55 records · Page 3Linked to original sources
PubMed1999

Effects of single dose of gamma-hydroxybutyric acid and lorazepam on psychomotor performance and subjective feelings in healthy volunteers.

OBJECTIVE: This study investigated the possible effects of gamma-hydroxybutyric acid (GHB) on human psychomotor performance and subjective feelings important for the safety of skilled performance. METHODS: Twelve healthy volunteers, six males and six females, aged 22-36 years, participated as subjects. Drugs and placebo were administered according to a single-dose, double-blind, balanced, four-way, crossover design. Treatments were separated by a wash-out period of 1 week and consisted of placebo, lorazepam 0.03 mg x kg(-1), GHB 12.5 mg x kg(-1) and GHB 25 mg x kg(-1). Subjects' psychomotor performance was assessed at baseline and at 15, 60, 120 and 180 min after treatment. Mood was assessed using 16 visual analogue scales, before treatment and 120 min later. Psychomotor performance was measured using the following tests: Critical Flicker Fusion. Response Competition Test, Critical Tracking Task, Choice Reaction Time and Visual Vigilance Task. RESULTS: GHB at both doses had no effects on attention, vigilance, alertness, short-term memory or psychomotor co-ordination (delta-placebo, P > 0.05); calmness increased with the lower dose and contentedness decreased significantly at both doses (delta-baseline, P < 0.05); adverse effects were limited to slight subjective feelings of dizziness and dullness, which disappeared 30-60 min after administration of the dose. Lorazepam caused impairment of psychometric functions. CONCLUSION: After single therapeutic doses, GHB does not induce changes in psychomotor performance and therefore the drug does not influence the ability to drive or work. However, repeated reports of the abuse potential of GHB and its usefulness in treating ethyl alcohol addiction indicate that it may play an "agonist-like" role, which means that it should only used under close medical supervision.

Adult↗
PubMed1999

A novel role for receptor-associated protein in somatostatin modulation: implications for Alzheimer's disease.

Receptor-associated protein appears to play an important role in low-density lipoprotein receptor-related protein trafficking. Since ligands for the low-density lipoprotein receptor-related protein have been implicated in Alzheimer's disease and normal functioning of this protein is indispensable for central nervous system development, deficient receptor-associated protein expression may result in central nervous system alterations. In this study, receptor-associated protein knockout mice were behaviorally tested and nervous system integrity was assessed via in situ hybridization and immunocytochemical/laser confocal microscopy methods. Receptor-associated protein knockout mice were found to be cognitively impaired in the Morris water maze compared to controls. In wild-type mice, the receptor-associated protein was found to be highly co-expressed with somatostatin in hippocampal and neocortical inhibitory neurons. Receptor-associated protein knockout mice, however, showed a significant decrease in number of somatostatin-expressing neurons of the CA1 region and somatostatin expression within these neurons. The decreased number of somatostatin neurons significantly correlated with cognitive impairment observed in the receptor-associated protein knockout mice. These results suggest a novel role for receptor-associated protein in modulating the functioning of somatostatin-producing neurons. Furthermore, this has implications for Alzheimer's disease pathogenesis, in which altered regulation of both somatostatin and the known low-density lipoprotein receptor-related protein ligands are a consistent finding.

Alzheimer Disease↗
PubMed1999

Efficacy of omeprazole versus ranitidine for symptomatic treatment of poorly responsive acid reflux disease-a prospective, controlled trial.

BACKGROUND: H2-receptor antagonists are widely used in patients with gastro-oesophageal reflux disease (GERD) and are frequently continued when symptoms persist. AIM: To compare the efficacy of omeprazole 20 mg once daily with that of ranitidine 150 mg twice daily in relieving GERD symptoms, in patients who remained symptomatic following a 6-week course of ranitidine therapy. METHODS: Patients with heartburn on at least 4 days/week but who did not have endoscopy to assess oesophageal mucosa could participate. This two-phase, prospective trial included a 6-week open-label phase (phase I), followed by an 8-week double-blind phase (phase II). Patients still symptomatic following treatment with ranitidine 150 mg twice daily (phase I) were randomized to double-blind treatment (phase II) with either omeprazole 20 mg once daily or ranitidine 150 mg twice daily. The primary efficacy variable was the proportion of patients with heartburn resolution during weeks 4 and 8 of phase II. RESULTS: Of the 533 patients with GERD who received ranitidine in phase I, 348 patients (65%) were still symptomatic. A total of 317 patients (59%) were randomized to double-blind treatment (phase II). At week 8, a significantly (P < 0.0004) greater proportion of omeprazole-treated patients (70%) experienced no more than mild heartburn compared with ranitidine-treated patients (49%). Complete resolution of heartburn also occurred in a significantly (P < 0. 00001) greater proportion of omeprazole-treated patients (46% vs. 16% of the ranitidine group at week 8). CONCLUSIONS: After 6 weeks of ranitidine treatment, the majority of patients with GERD were still experiencing moderate to severe heartburn. Omeprazole was significantly more effective than ranitidine in resolving heartburn in this group of patients.

Adult↗
PubMed1999

Evaluation of measured and calculated creatinine clearances as glomerular filtration markers in different stages of liver cirrhosis.

BACKGROUND: Discrepant results have been published regarding the suitability of creatinine clearance (C(Cr)) as a measure of glomerular filtration rate (GFR) in cirrhotic patients with normal renal function. SUBJECTS AND METHODS: In this study we evaluated the accuracy and precision of measured and calculated C(Cr) as indexes of GFR by comparing their values to those of inulin clearance (C(In)) in 10 healthy subjects and 20 patients with either Child's class A or Child's class C liver cirrhosis. RESULTS: The accuracy and precision of GFR estimates obtained by measuring C(Cr) were good in all three study groups. The mean values of the C(Cr)/C(In) ratio were 1.05, 1.03 and 1.04, respectively, and the corresponding coefficients of variations were 2.9, 2.9 and 3.8%. A close correlation between C(Cr) and C(In) was also found in each study group (r = 0.98, 0.99 and 0.97, respectively, with p < 0.001 in each case). C(Cr) calculated from serum creatinine by means of the Cockcroft-Gault formula (predicted GFR) proved to be a suitable measure of GFR in normal subjects and patients with Child's class A cirrhosis: the predicted-to-true GFR ratios were 0.93 and 0.94, respectively, CV was 12% in both cases. Moreover, a significant correlation between predicted and true GFR was observed in both groups (r = 0.73, p < 0.02 and r = 0.69, p < 0.025, respectively). On the contrary, in Child's class C cirrhotics, calculated C(Cr) significantly overestimated GFR (predicted-to-true GFR ratio 1.23, CV 20%) and no significant correlation was found between predicted and true GFR (r = 0.58, p > 0.05). CONCLUSION: In conclusion, this study shows that measured C(Cr) is a reliable index of GFR in cirrhotic patients, irrespective of the degree of liver dysfunction. Calculated C(Cr) is still an adequate marker of GFR in patients with compensated liver cirrhosis, whereas it overestimates GFR in patients with decompensated cirrhosis. A lower muscle mass, a reduced ability to convert creatine to creatinine, and the presence of ascites are most likely responsible for the overestimation of GFR by the Cockcroft-Gault formula in the latter patients.

Adult↗
PubMed1998

The use of neamine as a molecular template: identification of active site residues in the bacterial antibiotic resistance enzyme aminoglycoside 3'-phosphotransferase type IIa by mass spectroscopy.

Four novel aminoglycoside-based affinity inactivators were shown to covalently modify the active site of aminoglycoside 3'-phosphotransferase type IIa (APH(3')-IIa), an important resistance factor in bacteria for aminoglycoside antibiotics. Standard peptide mapping techniques failed with this enzyme. A novel mass spectroscopic analysis which combines protease digestion on the instrument probe, followed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is described which permitted rapid identification of the sites of protein modification. By this new technique, Glu-3 and Asp-23 were identified as active-site residues, the side chains of which potentially may serve as counter ions for the ammonium functionalities at positions 6', and 1 and 3 of the antibiotic substrates, respectively. These findings contradict previous assertions that the C-terminal third of the enzyme should form the active site, by placing the active site clearly in the N-terminal portion of the enzyme.

Aspartic Acid↗
PubMed1998

On-probe solid-phase extraction/MALDI-MS using ion-pairing interactions for the cleanup of peptides and proteins.

Samples originating from biological sources often contain a complex mixture of inorganic salts, buffers, chaotropic agents, surfactants/detergents, preservatives, and other solubilizing agents. However, the presence of these contaminants virtually ensures the failure of any subsequent analysis of the sample by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Sample cleanup procedures, therefore, must be performed prior to MALDI-MS analysis. This paper reports a probe-surface derivatization method that greatly simplifies this sample preparation process. MALDI probes possessing self-assembled monolayers (SAMs) terminated with ionic functional groups can rapidly extract peptides/proteins via ionic interactions from < or = 1-microL volumes of sample solutions placed directly on their surface. We have found that MALDI probes modified in this manner are a practical solution for analyzing very small volumes of peptide/protein solutions contaminated with high levels of inorganic salts, buffers, detergents, chaotropic agents, and other solubilizing agents.

Indicators and Reagents↗
PubMed1998

Optimization of a hydrophobic solid-phase extraction interface for matrix-assisted laser desorption/ionization.

Matrix-assisted laser desorption/ionization (MALDI) probe surfaces derivatized with octadecanethiol (C18) can be used as hydrophobic solid-phase extraction devices to isolate and desalt biopolymers directly on the probe surface. Using quantitative MALDI, it was possible to determine the approximate amount of peptide that bound to C18 surfaces and thus to calculate a surface density. It was determined that the amount of peptide bound at the probe surface was independent of the analyte concentration in the immersion solution (from high- to sub-ng ml-1 concentrations), but rather was dependent on the immersion time of the surface as it was exposed to the analyte. The capacity of C18-derivatized probes to bind biopolymers in fixed amounts frees the analyst from the necessity for adjusting analyte concentration through multiple step procedures such as serial dilution or vacuum drying. This time savings result in an overall increase in the efficiency of the MALDI technique.

Cytochrome c Group↗
PubMed1998

Is canine hepatocerebellar degeneration syndrome an animal model for carbohydrate-deficient glycoprotein syndrome in humans? An example of sequencing glycoprotein glycans with mass spectrometry.

The clinical symptoms and morphologic features of canine hepatocerebellar degeneration syndrome (CHD) bear striking resemblance to those of human carbohydrate-deficient glycoprotein syndrome (CDGS). The characteristic biochemical and molecular features of human CDGS lie in the truncated carbohydrate side chains of serum transferrin and numerous other glycoproteins of affected persons. Therefore, to explore the biochemical similarities between CHD and CDGS, we compared the structures of the carbohydrate side chains of canine serum transferrin isolated from a normal and a CHD-affected dog. Because of the very small quantity of serum transferrin available from the CHD-affected dog, we used analytical procedures that minimize sample consumption. In this scheme, we used microbore liquid chromatography interfaced to electrospray tandem mass spectrometry to identify and purify the glycopeptides from the tryptic digest of canine serum transferrin. This was followed by a series of exoglycosidase digestions coupled with mass spectrometric detection to sequence the carbohydrate side chains of the glycopeptides. With these procedures we completely characterized the carbohydrate chains attached to serum transferrin isolated from both a normal and a CHD-affected dog. However, we found no discernible differences in glycosylation of the carbohydrate side chains of serum transferrin from these two animals, suggesting that the biochemical defect in puppies with CHD differs from that in children with CDGS.

Alkylation↗
PubMed1998

Structure of a muramic acid containing capsular polysaccharide from the pathogenic strain of Vibrio vulnificus ATCC 27562.

Vibrio vulnificus strains isolated from septicemia cases and from the environment show a wide variety of capsular types. In an attempt to find common structural features which can be correlated with pathogenicity and toxicity, we have determined structures of the capsular polysaccharides (CPS) from several pathogenic strains. We report the complete structure of the polysaccharide from the pathogenic V. vulnificus strain ATCC 27562 using a combination of homonuclear and heteronuclear one-dimensional and two dimensional NMR experiments. The 13C and 1H NMR spectra, including the exchangeable amide proton resonances, have been completely assigned. The amide linkage between Ser and C6 of GalA has been unambiguously determined by water-suppressed 2D NOESY. To verify the structure established by NMR, we have fragmented the polymer employing the Smith degradation procedure. The Smith product identified by NMR and matrix-assisted laser desorption mass spectrometry is consistent with the proposed structure for the CPS, which is composed of D-GlcNAc, MurNAc, D-GalA, L-Rha and is serine-linked as shown: [formula: see text]

Bacteremia↗
PubMed1998

Determination of inulin clearance by bolus intravenous injection in healthy subjects and ascitic patients: equivalence of systemic and renal clearances as glomerular filtration markers.

AIMS: Determination of systemic inulin clearance by the standard technique of constant intravenous infusion has long been accepted as a reliable method for measuring glomerular filtration rate (GFR) without urine collection, except in oedematous patients. However, recent studies using standard clearance techniques have claimed that systemic inulin clearance is significantly greater than renal clearance and therefore overestimates GFR. The main purpose of this investigation was to re-evaluate the relationship between systemic and renal inulin clearance using a different technical approach. A reassessment was also made of inulin disposition kinetics. METHODS: Systemic and renal inulin clearances were simultaneously evaluated, in healthy subjects and patients with oedema and ascites, by analysis of the total area under the plasma concentration-time curve (AUC) following bolus intravenous injection. kenal clearance was calculated as the ratio of the total amount recovered in the urine to the AUC, and systemic clearance as dose/AUC. RESULTS: Inulin disposition kinetics were best described by a tri-exponential model. In healthy subjects the volume of the central compartment (mean (s.d.) value 3.86 (1.00) 70 kg(-1)) was slightly greater than the plasma volume; steady-state volume of distribution was 11.00 (1.21) 170 kg(-1), in accordance with the tenet that the inulin space is somewhat smaller than the extracellular fluid volume. The values of systemic and renal inulin clearances were very similar (96.1 (10.0) and 94.6 (12.5) ml min(-1) 70 kg(-1), respectively, in healthy subjects; 104.6 (16.3) and 102.6 (18.5) ml min(-1) in ascitic patients). They were also highly correlated to each other in both healthy subjects (r=0.96, P<0.001) and patients with ascites (r=0.98, P<O.001). CONCLUSIONS: The method described here constitutes a simpler and more precise technique for measuring renal inulin clearance than the standard method, which is based on constant infusion and timed collections of urine samples, since it avoids errors connected with short successive urine collections. By the present method we demonstrated that renal and systemic inulin clearances are virtually identical in both healthy subjects and patients with expanded extracellular fluid volume. Determination of systemic inulin clearance by the presently described technique is therefore a method of general validity for measuring GFR without urine collection.

Ascites↗
PubMed1998

Sexual transmission of hepatitis C virus and prevention with intramuscular immunoglobulin.

The sexual transmission of hepatitis C virus (HCV) has long been debated. The prevalence of infected at-risk partners varies from 0% to 30%. In a prospective study, the risk of infection was quantified in steady heterosexual partners and the prophylactic effect of normal human polyvalent immune serum globulin (ISG) was evaluated. A total of 899 at-risk partners of HCV-infected patients were enrolled in a single-blind randomized controlled trial and assigned to receive every 2 month 4 mL of intramuscular ISG from unscreened donors (450 partners) or placebo (499 partners). Seven partners developed acute HCV infection (increased aminotransferase levels and appearance of HCV-RNA): six of the placebo group (incidence density [ID] 12.00/1,000 person year; 95% confidence interval [CI] 3.0 to 21.61), and only one of the ISG-treated group (ID 1.98/1,000 person year; 95% CI 0 to 5.86). The risk of infection was significantly higher in controls versus treated individuals (p = 0.03). Six couples had genotype 1b (85%), and one couple had genotype 1a; HCV sequence homology strongly supported sexual transmission. Our trial demonstrates that HCV infection can be sexually transmitted and quantifies the risk of sexual transmission: for every year of at-risk sexual relationship, almost 1% of the partners became infected. Intramuscular ISG is safe and well tolerated. Unlike ISG from screened donors, ISG from donors unscreened for anti-HCV contains high titers of anti-gpE1/gpE2 neutralizing antibodies and high neutralizing activity. Anti-HCV hyperimmune globulin could be prepared from anti-HCV-positive blood units and could be used to protect sexual partners and in other at-risk situations of exposure to HCV infection.

Adult↗
PubMed1998

Selective hepatic arterial embolization of grade IV and V blunt hepatic injuries: an extension of resuscitation in the nonoperative management of traumatic hepatic injuries.

BACKGROUND: Recognizing the significant mortality and complications inherent in the operative management of blunt hepatic injuries, hepatic arterial embolization was evaluated as a bridge between operative and nonoperative interventions in patients defined as hemodynamically stable only with continuous resuscitation. METHODS: Seven of 11 patients with grade IV or V hepatic injuries identified by computed tomography underwent hepatic arterial embolization. A prospective evaluation of hepatic embolization based on subsequent hemodynamic parameters was assessed by matched-pair analysis. A summary of this study population's demographic data and outcomes is presented, including age, Glasgow Coma Scale score, Injury Severity Score, Revised Trauma Score, computed tomography grade, intensive care unit and hospital length of stay, transfusion requirements, complications, and mortality. RESULTS: No statistical difference was demonstrated between pre-embolization and postembolization hemodynamics and volume requirements. After embolization, however, continuous resuscitation was successfully reduced to maintenance fluids. Hepatic embolization was the definitive therapy for all seven patients who underwent embolization. CONCLUSION: Results of this preliminary investigation suggest that hepatic arterial embolization is a viable alternative bridging the therapeutic options of operative and nonoperative intervention for a subpopulation of patients with hepatic injury.

Adult↗
PubMed1997

A desalting approach for MALDI-MS using on-probe hydrophobic self-assembled monolayers.

One of the problems encountered in preparing samples for matrix-assisted laser desorption/ionization (MALDI) analysis is the presence of nonvolatile salts in the sample. This difficulty is often exacerbated by the necessity to prepare the sample in the appropriate sample-to-matrix ratio. This paper reports a probe surface derivatization method that greatly simplifies this sample preparation process. By constructing self-assembled monolayers of octadecyl mercaptan (C18) on the MALDI probe surface, we were able to generate a surface capable of reversibly binding polypeptides via hydrophobic interactions, which in turn, permits the analyte to be easily concentrated and desalted directly on the probe tip.

Chelating Agents↗