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Biomedical subjects

G Longo

Publications and source records attributed to G Longo.

At least 19 recordsLinked to original sources
PubMed1992

Pharmacokinetic properties of recombinant factor VIII compared with a monoclonally purified concentrate (Hemofil M). The Recombinate Study Group.

A recombinant FVIII preparation, Recombinate, was compared with a high-purity plasma-derived concentrate, Hemofil M, in 47 hemophilia A patients in a cross-over evaluation of pharmacokinetic properties. The recombinant material showed a significantly lower clearance, volume of distribution, and higher in vivo recovery, but a similar half-life to the plasma-based product. In a comparison with reported data from other standard concentrates, the recombinant preparation exhibited potentially better pharmacokinetic properties in that its clearance was slower and its half-life was longer. We conclude that the recombinant DNA method of preparation does not adversely affect the biological and pharmacological characteristics of the factor VIII molecule.

Adolescent↗
PubMed1992

Pharmacokinetics of two pasteurized factor VIII concentrates by different and multicenter assays of factor VIII activity.

We assessed the pharmacokinetic characteristics of a new high-purity pasteurized FVIII concentrate in comparison with an intermediate purity pasteurized concentrate, produced by the same manufacturer. The study was designed as a cross-over single-dose pharmacokinetic investigation in 8 non-bleeding patients with severe hemophilia A. All patients were given 25 IU/kg of each of the two concentrates, with an interval of at least one week between the two administrations. Decay curves were assessed by collecting 10 serial blood samples over 36 hours following the end of infusion. The concentration of Factor VIII in blood samples was determined in triplicate in three different laboratories using each of the following assay methods: a one-stage clotting assay, a two-stage clotting assay, and a two-stage chromogenic-peptide substrate assay. All pharmacokinetic parameters were calculated by model-independent methods. The two products were found to differ significantly both in the clearance, which was on average 13.8% lower for Haemate P, and in the in-vivo recovery, which was 11.7% lower for Factor VIII:C P on the average. In comparison with previous pharmacokinetic data obtained from other heated Factor VIII concentrates, the clearance of Haemate P was found to be significantly slower, while the half-life of both products was longer. No differences were observed in the Vd-area. These findings indicate that the purification procedures to which both products are subjected do not increase the in-vivo rate of plasma disappearance of Factor VIII.

Adolescent↗
PubMed1992

PKRD: a pharmacokinetic program for least-squares and bayesian analysis of repeated-dose pharmacokinetic curves.

A microcomputer program is presented which analyses multiple-dose pharmacokinetic curves using either a least-squares nonlinear analysis or a bayesian fit. The least-squares subroutine is designed to fit retrospective pharmacokinetic curves and can generate the so-called population pharmacokinetic parameters using the Standard Two-Stage method. The bayesian subroutine can instead be used prospectively to individualise the dosage regimen of a patient based on the concentrations measured in the initial phases of the drug treatment. All the pharmacokinetic subroutines of the program use the one-compartment model with either constant-rate intravenous infusion or oral route with zero-order absorption. The program was tested in a series of ten bone marrow transplantation patients treated with cyclosporine. The least-squares estimates of the one-compartment parameters, calculated by the program, were compared with those generated by the SIMKIN program.

Adolescent↗
PubMed1992

Aztreonam versus colistin-neomycin for selective decontamination of the digestive tract in patients undergoing bone marrow transplantation: a randomized study.

Aztreonam (Az), a minimally absorbable monobactam antibiotic, was compared to colistin plus neomycin (CN), for intestinal decontamination during Bone Marrow Transplantation (BMT) in a controlled study. Thirty-four consecutive patients were randomized in two groups and evaluated for number of febrile episodes, days of fever, fecal cultures and clinical symptoms related to infections or colonizations. No significant differences were observed suggesting that Az is at least as effective as the CN regimen and may be considered as an alternative approach for intestinal decontamination in BMT patients.

Aztreonam↗
PubMed1992

Histological behaviour of chronic hepatitis in patients treated with alpha interferon.

To evaluate the histological effects of alpha Interferon (IFN) therapy, serial liver biopsy specimens from 30 patients with chronic hepatitis were studied. The biopsies were examined using a scoring system. After 12 mths of IFN therapy responders were 8 out of 11 HBV infected patients, 10 out of 12 HCV infected patients and only 1 out of 7 patients with cryptogenetic hepatitis. As spontaneous improvement of hepatic changes is infrequent, our data indicate that in terms of histological patterns interferon therapy is effective in chronic viral hepatitis.

Hepatitis B↗
PubMed1992

Urinary excretion of citrate, glycosaminoglycans, magnesium and zinc in relation to age and sex in normal subjects and in patients who form calcium stones.

One hundred and ninety-seven healthy subjects and 104 patients with idiopathic calcium stone disease had their urinary excretion of citrate, glycosaminoglycans, magnesium, and zinc measured and the results correlated with sex and age. In normal subjects the daily excretion of citrate, magnesium, and zinc increased with age to a maximum during the fifth decade and remained relatively constant until the eighth decade when they decreased. The daily excretion of magnesium and zinc were higher in men than in women, which was attributed to the higher body weights of the men. The urinary excretion of citrate, magnesium, and zinc related to creatinine remained relatively constant with age in adult life; analyses of magnesium and zinc excretion rates divided by urine creatinine did not distinguish men from women. There was no significant difference between men and women for citrate excretion in 24 hour urine, but the citrate:creatinine ratio was significantly higher in women than men. The higher citrate excretion in women may explain the lower incidence of calcium stones in women. The highest glycosaminoglycan excretion rates were seen during the first two decades which is why children and teenagers are less prone to develop calcium stones in spite of high urinary calcium concentrations. Urinary citrate and magnesium excretion were lower, and glycosaminoglycan and zinc excretion were higher, in stone formers than in controls. It seems that a decreased excretion of citrate and magnesium together with an increased excretion of calcium, may contribute to the formation of calcium stones. The role of urinary glycosaminoglycans and zinc in the formation of calcium stones remains uncertain.

Adolescent↗
PubMed1992

[Vecuronium in pediatric anesthesia. Repeated bolus vs continuous infusion].

Vecuronium bromide was employed in 26 pediatric patients; 18 received vecuronium infusion and 11 intermittent bolus administration. The aim of the study was to evaluate the pharmacodynamics of the drug, the lack of cumulative properties, the best infusion rate, the possible advantage of the infusion technique. Neuromuscular blockade monitoring was performed in all patients. In the results, vecuronium shows lack of cumulative properties. The best infusion rate was 0.13 +/- 0.02 mg/kg/h. The continuous infusion allows the employment of lesser doses of the drug than the intermittent administration.

Adolescent↗
PubMed1992

[Metastasis and markers].

Tumor markers are antigens which can be associated with certain malignancies. A variety of markers have been demonstrated in genitourinary tumors. The best known examples are human chorionic gonadotropin (bHCG) and alpha-fetoprotein (AFP) for testicular tumors, prostatic acid phosphatase (PAP) and prostatic specific antigen (PSA) for prostatic cancer. The plasma levels of these substances are influenced by the tumor mass and therefore by the tumor stage. Markedly elevated plasma levels can be demonstrated when metastases are present, although a few patients without metastases may elaborate abnormal amount of markers. The removal of the primary tumor leads to a fall to normal levels: a still increased level indicates residual primary tumor or the presence of metastases. Measurements of markers are also of value in estimating the effects of medical treatment and in detecting local or distant recurrences.

Acid Phosphatase↗
PubMed1992

Hemodialysis with defibrotide: effects on coagulation parameters.

In a crossover study conducted with eight uremic patients maintained on hemodialysis, the Authors compared the effects of heparin (100 IU/kg at the start of dialysis) and defibrotide (400 mg at the start, repeated at 2 hours of ongoing dialysis) on the parameters of blood coagulation (VIII:C, AT III, TAT, PC antigen and activity, PS, and FPA), each being assessed before dialysis and at 2, 3 and 4 hours of the ongoing procedure. Heparin-assisted dialysis resulted in a significant rise of VIII:C and AT III; with defibrotide, instead, there was evidence of thrombin activation (increased FPA and TAT). PC levels were raised with both dialysis modalities; however, PC activity and PS levels were increased only in defibrotide-assisted dialysis. There were no adverse reactions or evidence of fibrin formation. These results confirm the antithrombotic activity of defibrotide in the course of dialysis and indicate that this action is independent of thrombin neutralization.

Antithrombin III↗
PubMed1992

[Resistance to non-depolarizing myorelaxants. Our experience with 3 clinical cases].

The Authors report their own experience in three patients that showed reduced sensitivity to atracurium or vecuronium. Two patients were affected by neoplastic diseases and one by hand trauma. Doses of 0.5 mg/kg of atracurium and 0.08 mg/kg of vecuronium were unable to establish a complete neuromuscular blockade. The Authors review the main clinical situations in which resistance to non-depolarizing muscle relaxants is known: burns, hepatic diseases, chronic therapy with anticonvulsant drugs. Possibly, such events are due to fast elimination of the drug, or to an increased number of acetylcholine nicotinic receptors, or to an unknown acutely acting circulating factor, or to increased binding of the drug to plasma proteins. Up to date, no well-established explanation is available.

Adolescent↗
PubMed1992

Recombinant human erythropoietin for treatment of myelodysplastic syndromes.

Nine patients with myelodysplastic syndromes and one patient with agnogenic myeloid metaplasia have been treated with recombinant human erythropoietin (rhEpo), at the dose of 150 U/kg/day. Although serum Epo levels were correlated with hemoglobin concentrations in the whole population of patients, they clearly appeared inadequate in some instances, if compared to those of a group of control subjects with iron deficiency anemia. Moreover, no correlation was found between serum Epo and reticulocytes. Six patients showed a partial or complete response to the treatment and the outcome was not correlated with the pre-therapy serum Epo levels; however, serum Epo was less than 100 mU/ml in three of four patients who achieved a complete response. The mechanism(s) by which Epo stimulated erythrocyte production in myelodysplastic patients is unclear, because the number of both the reticulocytes and erythroid progenitors remained unchanged during and at the conclusion of a three months' therapy. Further studies are needed to better define the optimal dosage required to correct anemia in myelodysplastic syndromes, and to clarify rhEpo mechanism of action in these diseases.

Aged↗
PubMed1991

Reproducibility of one-stage, two-stage and chromogenic assays of factor VIII activity: a multi-center study.

This study was aimed at assessing the reproducibility of Factor VIII assays between different laboratories using the same reagents. A total of 176 post-dose plasma samples were obtained from 8 Italian subjects with hemophilia-A treated with a single dose of Factor VIII concentrates. Three laboratories (in FRG, Italy, and Sweden) participated in the study. Frozen aliquots of each sample were dispatched to each of the laboratories, where the aliquots were assayed using the same one-stage, two-stage and chromogenic methods. The one-stage and the chromogenic methods were well reproducible between the three centers: pairwise correlation analyses yielded r-values ranging from 0.88 to 0.91 for the one-stage method and from 0.91 to 0.96 for the chromogenic method. The agreement between these two assays was less evident in samples with activity below 200 IU/L in which the one-stage gave, on average, higher Factor VIII concentrations than those provided by the chromogenic method. The two-stage method was not well reproducible, and the pairwise r-values ranged from 0.48 to 0.73. Our study emphasises the need to develop multi-center quality control programs to verify the reproducibility of Factor VIII assays.

Adolescent↗
PubMed1991

Comparative evaluation of the pharmacokinetics of three monoclonal factor VIII concentrates.

Hemofil M, Monoclate HT, and Monoclate P are high-purity Factor VIII concentrates, obtained from plasma by immunoaffinity chromatography with monoclonal antibodies specific for Factor VIII (Hemofil M) or von Willebrand Factor (Monoclate HT and Monoclate P). The concentrates are subjected to virucidal treatments: a solvent/detergent method (TNBP/Na-cholate) for Hemofil M, heating in the lyophilized state and in solution (pasteurization) for Monoclate HT and Monoclate P, respectively. Since these differences in the manufacturing process might result in different in vivo characteristics of the concentrates, we compared their in vivo behavior in a cross-over, single-dose, pharmacokinetic study performed in 10 non-bleeding patients with severe hemophilia A. The experimental conditions (Factor VIII dose, number and timing of blood sampling, Factor VIII assay methods, calculation of pharmacokinetic parameters) were identical for the three products. The results showed that the clearance, the mean residence time, and the volume of distribution did not differ among the three products.

Factor VIII↗
PubMed1991

Hepatitis B virus variant, with a deletion in the preS2 and two translational stop codons in the precore regions, in a patient with hepatocellular carcinoma.

We analyzed hepatitis B virus (HBV) genomes obtained from serum samples and liver biopsy specimen of a chronic HBsAg/anti-HBe carrier with hepatocellular carcinoma (HCC). Before the liver biopsy, performed at the time of HCC diagnosis, the patient had been followed for 2 years; the serum samples collected in that period resulted negative for HBV-DNA dot blot hybridization. The hepatic DNA was at first examined by Southern blot, but no HBV sequence was detected. Polymerase chain reaction (PCR) amplification revealed the presence of HBV genomes in DNA extracted from the liver tissue and from two serum samples collected, respectively, 1 and 2 years before the biopsy. Direct sequence of the amplified preC/C and preS regions showed that the viral populations present in serum and liver were identical and that they had a 34 nucleotide deletion in the preS2 region, while the preC region presented two mutations each introducing a translational stop codon, one at the carboxy terminal end and the other at the second codon of the region, both able to prevent HBeAg expression. These results identify a new HBV variant which was selected during a chronic infection, and had very low levels of replication as shown by its detection only after PCR amplification.

Base Sequence↗
PubMed1991

HBe antibody unrelated to 'e minus' hepatitis B virus variant infection in patients with chronic type D hepatitis.

The presence of HBV-DNA sequences was evaluated in DNA extracted from serum samples, peripheral blood lymphocytes and liver biopsy specimens of five HBsAg/anti-HBe-positive carriers with chronic HDV infection. DNAs were tested by polymerase chain reaction (PCR) amplification technique using two pairs of oligonucleotide primers specific for the preC/C and S regions of the HBV; viral sequences were found exclusively in liver extracts and only in three out of the five cases. The direct sequencing of the amplified preC/C regions showed wild-type sequences in two cases, while in the third case a combination of 'wild' and 'e minus variant' viral populations was observed. Moreover, liver DNA of one positive case was electrophoresed through a low melting agarose gel and the following amplification, performed on DNA re-extracted from three different fragments of the gel, showed the presence of free HBV genomes but the absence of replicative intermediate forms. These results show that anti-HBe positivity is not constantly related to precore mutant HBV infection and suggest that HDV inhibits HBeAg production. Moreover, as it was observed in 'e minus' HBV variants, also during a chronic HBV wild-type infection, the viral replication might be suppressed to undetectable levels.

Base Sequence↗
PubMed1991

Histological features in liver biopsy specimens of patients with acute reactivation of chronic type B hepatitis.

The histological features in liver biopsy specimens from seven patients with acute exacerbation of chronic type B hepatitis were analysed. In all the cases typical changes of acute hepatitis were superimposed on signs of chronicity, namely peripheral piecemeal necrosis, plasma cell infiltration and porto-portal bridges, which in three cases contained elastic fibres. Reactivation of silent hepatitis B virus chronic infection should be considered as a possible diagnosis in any patient with histological findings of acute and chronic hepatitis.

Biopsy↗