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Biomedical subjects

G Longo

Publications and source records attributed to G Longo.

At least 163 records · Page 9Linked to original sources
PubMed1986

Pharmacokinetics of a new heat-treated concentrate of factor VIII estimated by model-independent methods.

We evaluated the pharmacokinetic properties of Kryobulin TIM3, a new heat-treated Factor VIII concentrate which has recently become available in Europe. Twelve patients with classic hemophilia were studied. In each patient, Factor VIII was given as a single dose (ranging from 11.6 to 30.3 units/kg) after which eight serial blood samples were drawn to characterize the disappearance of Factor VIII from the plasma. Model-independent (noncompartmental) methods were used for pharmacokinetic analysis. The following pharmacokinetic parameters of Factor VIII (mean +/- SD) were estimated: clearance = 3.83 +/- 0.99 ml/h/kg; mean residence time = 15.9 +/- 4.5 h; volume of distribution at steady state = 55.6 +/- 9.3 ml/kg; in-vivo recovery = 129 +/- 29%. The pharmacokinetic parameters of Kryobulin TIM3 obtained in our study are very similar to those previously reported for the untreated concentrate. Thus, our findings suggest that the dosing guidelines previously available for the untreated concentrate need not be revised when using the treated product.

Adolescent↗
PubMed1986

Platelet function and coagulation studies in patients with mitral valve prolapse.

Twenty-eight consecutive patients with mitral valve prolapse (MVP), seven of whom had previous cerebrovascular disorders (CVD), were studied for platelet function and coagulation tests. While platelet function tests were found to be normal with the exception of platelet aggregation rate (PAR), there was a significant rise of factors VIII vWF:Ag (Von Willebrand) and (FPA) fibrinopeptide A. Six cases had high levels of both these factors, suggesting the existence of a particular subset of patients with MVP, with a higher risk of thromboembolic episodes, although only three out of seven patients with previous CVD had either FPA or VIII vWF:Ag levels. The broad spectrum of subjects with MVP probably explains the different results obtained when studying platelet function and coagulation factors. Therefore, larger population studies and prolonged follow-up of cases with either coagulation abnormalities similar to the ones found in the present report and/or altered platelet function tests are suggested to discover if it is possible to detect patients with a potential for thromboembolism.

Adolescent↗
PubMed1986

A microcomputer program for individualizing factor VIII dosage in hemophilia patients undergoing major surgery.

A pharmacokinetic program that allows individualization of Factor VIII dosage regiments in hemophilia patients undergoing major surgery is described. The program, which is designed for the IBM PC microcomputer and compatible machines, is based upon the one-compartment open model with instantaneous input. In the framework of such a pharmacokinetic model, it is assumed that the elimination of Factor VIII is faster during the early post-operative period and that it decreases progressively over the following days. Since Factor VIII half-life is dependent on the time elapsed since the operation (short half-life values during the early post-operative period, longer half-life values thereafter), the pharmacokinetic model is a nonlinear one. A first-order 'variation' rate constant is used to describe the prolongation of Factor VIII half-life from the initial value immediately after surgery to the final value achieved several days later. Individualized estimation of the patient's kinetic parameters (initial half-life, 'variation' rate constant and volume of distribution) is performed through the Bayesian method. Therefore, for such estimation the program exploits the Factor VIII plasma levels measured in the individual patient as well as the population pharmacokinetic data of Factor VIII. After estimating the individual's Bayesian parameters, the program predicts the dosage regimen that will elicit the desired time-course of Factor VIII plasma levels. If requested, the program is able to calculate the least-squares estimates for the parameters of the pharmacokinetic model and dosage prediction can also be made on the basis of such estimates. The least-squares estimates are useful for calculating population pharmacokinetic parameters according to the Standard Two-Stage method. Some examples of clinical use of the program are presented.

Computers↗
PubMed1986

HTLV-III seropositivity in symptom-free Italian haemophiliacs. Correlation with consumption of commercial concentrate and abnormalities of T and B lymphocytes.

Various immunological parameters exploring both T- and B-cell functions were determined in a group of 74 symptom-free Italian haemophiliacs treated with commercial concentrate imported from the USA and were correlated with the presence in their serum of antibody to HTLV-III. There was a strong correlation between HTLV-III seropositivity and the amount of concentrate consumed. A significant correlation between HTLV-III seropositivity and T-cell alterations, such as T4/T8 ratio less than 1 and reduction in the absolute number of T4+ lymphocytes, or B-cell alterations such as hypergammaglobulinaemia and enhanced spontaneous IgG synthesis in vitro, was also observed.

Antibodies, Viral↗
PubMed1986

ABR in multiple sclerosis. Ipsi- versus contralateral derivation.

Brainstem auditory evoked potentials (ABR) were recorded simultaneously between vertex and ear lobe, ipsi- and contralateral to the stimulated ear in 53 subjects with confirmed (19) or undefined (34) multiple sclerosis. Results were compared with those obtained in a control group of 20 normal-hearing adults. The control group showed that significant latency differences exist between ipsilateral and contralateral recordings. Definition of abnormality was based on absence and separation of waves. The results showed that the use of contralateral derivation in ABR recordings increased detectability from 74% to 89% in patients with confirmed MS and from 9% to 21% in cases of undefined MS. It is proposed that parameters of contralateral ABRs be included among the criteria used for the otoneurological diagnosis of patients with CNS lesions.

Adolescent↗
PubMed1986

Elastic intramedullary nailing in shaft fractures of the femur and tibia.

The excellent results obtained in the stabilization of lateral and subtrochanteric fractures of the neck of the femur by the use of Ender nails have encouraged us to extend this method, with some technical modifications, to shaft fractures of the femur. It is proposed to be an alternative in the surgical treatment of such fractures. We propose to use this alternative when local conditions counterindicate, or the risk factor in other surgical techniques is too high. This method is simple, easily executed and assures a rapid and functional recovery. Ender intramedullary nailing achieves a dynamic stabilization controlled by the elasticity of the nails, muscle tone and weight bearing. The stabilization allows slight interfragmentary movements and produces the formation of periosteal bone callus.

Bone Nails↗
PubMed1986

Changes in bilirubin transport across the liver by the flavonoids (+)-cyanidanol-3 and palmitoyl-catechin.

The apparent maximal transport capacity (Tm) of the liver for bilirubin was studied in rats after oral treatment for two weeks with the two flavonoids (+)-cyanidanol-3 and palmitoyl-catechin in order to investigate a possible mechanism of action on jaundice described in humans. (+)-Cyanidanol-3 produces no changes in bilirubin-Tm, and the analysis of bilirubin and its conjugates in the different compartments reveals a decreased amount of the whole bilirubin taken up by the liver. Palmitoyl-catechin, a more lipophilic derivative of catechin, produces a slight increase in bilirubin-Tm. This appears related to the increased conjugation rate demonstrated in vitro for bilirubin. A multicompartimental analysis shows a different distribution of bilirubins as compared to controls. It is likely that physicochemical changes of the membrane environment, where the enzyme is buried, have modified the capacity of the hepatocyte to dispose bilirubin.

Animals↗
PubMed1986

Remote masking, brief tone audiometry and critical ratio in sensorineural hearing losses.

Aim of this study is to evaluate in ears with different kinds of perceptive disorders the relationships between Critical Ratio (CR), Remote Masking (RM) and Brief Tone Audiometry (BTA) in order to analyse to what extent cochlear efficiency depends on functional properties of the mechanical extrasensorial structures and/or of the sensorial elements in the inner ear. Present results show that in ears with non retrocochlear sensorineural losses CR results are more often affected than RM and BTA. A reduced cochlear efficiency is related more to a failure of the mechanical properties than to dysfunctions of the cellular elements within the inner ear; presumably, micromechanisms not yet understood or unknown interfere with the efficiency of the cochlea.

Adolescent↗
PubMed1985

Polyalbumin receptors, hepatitis B surface antigen (HBsAg), and HBsAg/IgM complexes in HBsAg positive patients with and without delta superinfection.

Receptors for polymerized human albumin are found at high titres during high-level hepatitis B virus (HBV) replication and in small amounts in chronic low-level infection. Complexes between hepatitis B surface antigen (HBsAg) and IgM without specificity for HbsAg are expressed in a pattern similar to that of receptors. Anti-albumin antibodies could be involved in their formation. Delta infection depresses the synthesis of gene products of HBV. To assess whether delta modifies the expression of receptors on HBsAg and the level of HBsAg/IgM complexes, and if anti-albumin antibodies are actually part of the complex, we tested sera from 86 subjects with acute and chronic HBV infection. Our findings show that the amounts of circulating receptors and HBsAg/IgM are proportional to the concentration of HBsAg and thus probably to the degree of viral replication. We did not find any correlation between circulating anti-albumin antibodies of the IgM class and HBsAg/IgM complexes. Delta infection depresses HBsAg synthesis and causes a related decrease in receptors and HBsAg/IgM titres if superimposed on the more active stage of HBV infection. When HBsAg, receptors, and HBsAg/IgM are at low levels, no further depression is caused by delta infection. HBsAg/IgM titre is not enhanced by presence of anti-delta antibodies, thus excluding a role of the latter in forming these complexes.

Acute Disease↗
PubMed1985

A calculator program for clinical application of the Bayesian method of predicting plasma drug levels.

A pharmacokinetic program that allows individualization of drug dosage regimens through the Bayesian method is described. The program, which is designed for the Hewlett-Packard HP-41 CV calculator, is based upon the one-compartment open model with either instantaneous or zero-order absorption. Individualized estimation of the patient's kinetic parameters (clearance and volume of distribution) is performed by analyzing the plasma levels measured in the patient as well as considering the population data of the drug. After estimating the individual kinetic parameters by the Bayesian method, the program predicts the dosage regimen that will elicit the desired peak and trough plasma levels at steady state. For comparison purposes, the least-squares estimates for clearance and volume of distribution are calculated, and dosage prediction can also be made on the basis of the least-squares estimates. The least-squares estimates can be used to calculate population pharmacokinetic parameters according to the Standard Two-Stage method. Several examples of clinical use of the program are presented. The examples refer to patients with classic hemophilia who were treated with Factor VIII concentrates. In these patients, the Bayesian kinetic parameters of Factor VIII have been estimated through the calculator program. The Bayesian parameter estimates generated by the HP-41 have been compared with those determined by a Bayesian program (ADVISE) designed for microcomputers.

Computers↗
PubMed1985

Actinomycosis of the prostate.

We report a case of actinomycosis of the prostate with symptoms of acute prostatitis. Laparotomy was required to establish an etiological diagnosis. Long-term therapy with erythromycin resulted in a clinical cure.

Actinomycosis↗
PubMed1985

Kinetic evaluation of four Factor VIII concentrates by model-independent methods.

Single-dose kinetics of 4 Factor VIII concentrates (Kryobulin, Hemofil T, Koate, cryoprecipitate) were studied in 41 patients with haemophilia-A. Model-independent methods were adopted for calculating the kinetic parameters (area under the curve, clearance, area under the moment curve, mean residence time, volume of distribution at steady-state). No substantial difference was observed in the kinetic characteristics of the 4 Factor VIII concentrates. A considerable interindividual variability of the calculated kinetic parameters was demonstrated for all concentrates. Our findings support the need to individualize Factor VIII dosage.

Adolescent↗