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Biomedical subjects

M Marchetti

Publications and source records attributed to M Marchetti.

At least 55 records · Page 3Linked to original sources
PubMed2000

Deciding when to intervene: a Markov decision process approach.

The aim of this paper is to point out the difference between static and dynamic approaches to choosing the optimal time for intervention. The paper demonstrates that classical approaches, such as decision trees and influence diagrams, hardly cope with dynamic problems: they cannot simulate all the real-world strategies and consequently can only calculate suboptimal solutions. A dynamic formalism based on Markov decision processes (MPPs) is then proposed and applied to a medical problem: the prophylactic surgery in mild hereditary spherocytosis. The paper compares the proposed approach with a static approach on the same medical problem. The policy provided by the dynamic approach achieved significant gain over the static policy by delaying the intervention time in some categories of patients. The calculations are carried out with DT-Planner, a graphical decision aid specifically built for dealing with dynamic decision processes.

Cholecystectomy↗
PubMed2000

Walking index for spinal cord injury (WISCI): an international multicenter validity and reliability study.

STUDY DESIGN: Construction of an international walking scale by a modified Delphi technique. OBJECTIVE: The purpose of the study was to develop a more precise walking scale for use in clinical trials of subjects with spinal cord injury (SCI) and to determine its validity and reliability. SETTING: Eight SCI centers in Australia, Brazil, Canada (2), Korea, Italy, the UK and the US. METHODS: Original items were constructed by experts at two SCI centers (Italy and the US) and blindly ranked in an hierarchical order (pilot data). These items were compared to the Functional Independence Measure (FIM) for concurrent validity. Subsequent independent blind rank ordering of items was completed at all eight centers (24 individuals and eight teams). Final consensus on rank ordering was reached during an international meeting (face validation). A videotape comprised of 40 clips of patients walking was forwarded to all eight centers and inter-rater reliability data collected. RESULTS: Kendall coefficient of concordance for the pilot data was significant (W=0. 843, P<0.001) indicating agreement among the experts in rank ordering of original items. FIM comparison (Spearman's rank correlation coefficient=0.765, P<0.001) showed a theoretical relationship, however a practical difference in what is measured by each scale. Kendall coefficient of concordance for the international blind hierarchical ranking showed significance (W=0.860, P<0.001) indicating agreement in rank ordering across all eight centers. Group consensus meeting resulted in a 19 item hierarchical rank ordered 'Walking Index for Spinal Cord Injury (WISCI)'. Inter-rater reliability scoring of the 40 video clips showed 100% agreement. CONCLUSIONS: This is the first time a walking scale for SCI of this complexity has been developed and judged by an international group of experts. The WISCI showed good validity and reliability, but needs to be assessed in clinical settings for responsiveness.

Australia↗
PubMed2000

Cost-effectiveness of epoetin and autologous blood donationin reducing allogeneic blood transfusions incoronary artery bypass graft surgery.

BACKGROUND: Coronary artery bypass graft (CABG) surgery accounts for a substantial portion of all allogeneic units of blood transfused. Drugs and autologous blood donation (ABD) are alternative or adjunctive methods for reducing complications and costs induced by allogeneic blood transfusions. Recombinant human erythropoietin (epoetin) has the potential to decrease perioperative need for allogeneic blood during CABG, but its high cost calls for a careful economic evaluation before it can be recommended for widespread use. STUDY DESIGN AND METHODS: A decision tree was used to compare a hypothetical strategy of no epoetin with one in which epoetin was utilized to control blood transfusion needs in CABG; each strategy was tested with and without ABD. The impact of these strategies on both the quality-adjusted life years (QALYs) and costs ($US) was calculated. RESULTS: Using epoetin alone and with ABD, respectively, avoided the transfusion of 0.61 and 1.35 units of allogeneic blood per patient and saved 0.000086 and 0.000146 QALYs per patient. This made cost-effectiveness (CE) higher than $7 million and $5 million for each QALY saved, respectively. ABD alone cost more than $1 million per QALY saved. If the risk of bacterial infections following allogeneic transfusions was included in the model, epoetin alone cost $6288 per QALY saved, while ABD, both alone and with epoetin, saved money. CONCLUSION: On the basis of the existing evidence, neither of the blood-saving strategies modeled was a cost-effective means of avoiding the deleterious health effects of perioperative blood transfusions in CABG. However, if allogeneic blood-related infections were to be considered, both ABD and epoetin would be acceptable interventions.

Aged↗
PubMed2000

Infection of human enterocyte-like cells with rotavirus enhances invasiveness of Yersinia enterocolitica and Y. pseudotuberculosis.

Mixed infection with rotavirus and either Yersinia enterocolitica or Y. pseudotuberculosis was analysed in Caco-2 cells, an enterocyte-like cell line highly susceptible to these pathogens. Results showed an increase of bacterial adhesion and internalisation in rotavirus-infected cells. Increased internalisation was also seen with Escherichia coli strain HB101 (pRI203), harbouring the inv gene from Y. pseudotuberculosis, which is involved in the invasion process of host cells. In contrast, the superinfection with bacteria of Caco-2 cells pre-infected with rotavirus resulted in decreased viral antigen synthesis. Transmission electron microscopy confirmed the dual infection of enterocytes. These data suggest that rotavirus infection enhances the early interaction between host cell surfaces and enteroinvasive Yersinia spp.

Adhesins, Bacterial↗
PubMed2000

Prognostic value of bcl-2, p53 and Ki-67 in invasive squamous carcinoma of the uterine cervix.

The aim of this study was to evaluate the immunohistochemical expression of the markers bcl-2, p53 and Ki67 and their relation to the classical clinical-pathological prognostic factors in invasive squamous cellular carcinoma of the cervix. Since bcl-2 and p53 are implicated in the regulation of programmed cell death, very probably they play a role in carcinogenesis and consequently become prognostic factors.

Adult↗
PubMed2000

Extended anticoagulation for prevention of recurrent venous thromboembolism in carriers of factor V Leiden--cost-effectiveness analysis.

There is much debate over the appropriateness of prescribing prolonged anticoagulation to heterozygous carriers of factor V Leiden suffering a first episode of deep vein thrombosis (DVT). We, thus used meta-analysis to estimate from six eligible studies the summary odds-ratio of recurrent DVT in carriers of factor V Leiden versus non-carriers: 1.36 (CI, 1.05-1.78). After that, we used a decision model to compare lifelong costs and benefits of 6 months standard anticoagulation with those of screening for carriers of factor V Leiden and extending for 2 years their anticoagulation. Screening was a cost-effective strategy, since it provided 2 additional quality-adjusted days of life per patient at the cost of $12,833 per quality-adjusted year of life saved, as compared to standard management. However, screening was not cost-effective in patients who were predicted to incur fatal bleeding at a rate higher than 0.34% per year or recurrent DVT at a rate lower than 9% in the first 2 years. The screening policy was cost-saving if restricted to patients with idiopathic DVT and compliant to warfarin therapy.

Anticoagulants↗
PubMed2000

Prognostic value of protein p53 and ki-67 in invasive vulvar squamous cell carcinoma.

The aim of this research was to detect new valid prognostic indicators that allow us to choose the best therapy and follow-up for patients with a poor prognosis. One hundred and twenty-nine patients with invasive squamous carcinoma of the vulva treated at the Gynecology Clinic of the University of Padua between January 1, 1975 and December 31, 1999 have been evaluated: Protein p53 and ki-67 were studied by immunohistochemical investigations and their prognostic significance was evaluated. The relation with the classic clinico-pathological prognostic factors was also studied. The results showed a close association between tissue overexpression of the two proteins and clinico-pathological characteristics of the aggressivity of the neoplasm. Moreover, the group of positive p53 patients with a diffuse distribution pattern of ki-67 resulted in having a somewhat shorter survival with respect to the groups with negative p53 and/or a focal pattern. Such negative prognostic significance was confirmed by the results of the multivariate analysis performed with the Cox model which shows that patients with p53 positive values and a diffuse pattern have a higher relative risk of death compared to patients with p53 negative values and focal pattern (p=0.0001). The statistical significance of the prognostic value of the association of p53 and ki-67 thus seems to give these two factors greater weight with respect to the others we investigated.

Aged↗
PubMed1999

Bovine lactoferrin peptidic fragments involved in inhibition of herpes simplex virus type 1 infection.

Bovine lactoferrin (BLf) prevents the infection of some enveloped and naked viruses. To identify BLf sequences responsible for the antiviral activity, we tested 31 HPLC fractions, derived from tryptic digestion of BLf, toward herpes simplex virus type 1 (HSV-1). Only a few HPLC purified fragments were active against HSV-1, even if at lower extent than the native undigested BLf. Two large fragments, one corresponding to the C-lobe (amino acid sequence 345-689) and the other corresponding to a large portion of the N-lobe (1-280), were inhibitors of HSV-1 infection, while a smaller part of the N-lobe (86-258) was ineffective. Among the low-molecular-weight fragments, only two small peptides, which coeluted in a single chromatographic peak, were effective towards HSV-1. These peptides, both present in the N-lobe, were identified as peptides 222-230 (ADRDQYELL) and 264-269 (EDLIWK). The same peptides, chemically synthesised, were able to inhibit HSV-1 infection only when they were assayed in association.

Animals↗
PubMed1999

Neutrophil activation and hemostatic changes in healthy donors receiving granulocyte colony-stimulating factor.

Granulocyte colony-stimulating factor (G-CSF) enhances neutrophil functions in vitro and in vivo. It is known that neutrophil-derived products can alter the hemostatic balance. To understand whether polymorphonuclear leukocyte (PMN) activation, measured as PMN degranulation and phenotypical change, may be associated to hemostatic alterations in vivo, we have studied the effect of recombinant human G-CSF (rHuG-CSF) administration on leukocyte parameters and hemostatic variables in healthy donors of hematopoietic progenitor cells (HPCs). Twenty-six consecutive healthy donors receiving 10 micrograms/kg/d rHuG-CSF subcutaneously for 5 to 7 days to mobilize HPCs for allogeneic transplants were included in the study. All of them responded to rHuG-CSF with a significant white blood cell count increase. Blood samples were drawn before therapy on days 2 and 5 and 1 week after stopping rHuG-CSF treatment. The following parameters were evaluated: (1) PMN activation parameters, ie, surface CD11b/CD18 antigen expression, plasma elastase antigen levels and cellular elastase activity; (2) plasma markers of endothelium activation, ie, thrombomodulin (TM) and von Willebrand factor (vWF) antigens; (3) plasma markers of blood coagulation activation, ie, F1+2, TAT complex, D-dimer; and (4) mononuclear cell (MNC) procoagulant activity (PCA) expression. The results show that, after starting rHuG-CSF, an in vivo PMN activation occurred, as demonstrated by the significant increment of surface CD11b/CD18 and plasma elastase antigen levels. Moreover, PMN cellular elastase activity, which was significantly increased at 1 day of treatment, returned to baseline at day 5 to 6, in correspondence with the elastase antigen peak in the circulation. This change was accompanied by a parallel significant increase in plasma levels of the two endothelial and the three coagulation markers. The PCA generated in vitro by unstimulated MNC isolated from rHuG-CSF-treated subjects was not different from that of control cells from untreated subjects. However, endotoxin-stimulated MNC isolated from on-treatment individuals produced significantly more PCA compared with both baseline and control samples. All of the parameters were decreased or normal 1 week after stopping treatment. These data show that rHuG-CSF induces PMN activation and transiently affects some hemostatic variables in healthy HPC donor subjects. The clinical significance of these findings remains to be established.

Adolescent↗
PubMed1999

Inhibition of poliovirus type 1 infection by iron-, manganese- and zinc-saturated lactoferrin.

In this study we investigated the inhibitory activity of different milk proteins on poliovirus infection in Vero cells. Proteins analyzed were mucin, alpha-lactalbumin, beta-lactoglobulin, and bovine and human lactoferrin. Viral cytopathic effect was not prevented by mucin, alpha-lactalbumin or beta-lactoglobulin, whereas the lactoferrins tested were able to inhibit the replication of poliovirus in a dose-dependent manner. Further experiments were carried out in which apo- and native lactoferrin or lactoferrin fully saturated with ferric, manganese or zinc ions were added to the cells during different phases of viral infection. Results obtained demonstrated that all lactoferrins were able to prevent viral replication when present during the entire cycle of poliovirus infection or during the viral adsorption step. Only zinc lactoferrin strongly inhibited viral infection when incubated with the cells after the viral attachment, being the inhibition directly correlated with the degree of zinc saturation. Our results demonstrated that all lactoferrins interfered with an early phase of poliovirus infection; zinc lactoferrin was the sole compound capable of inhibiting a phase of infection subsequent to virus internalization into the host cells.

Animals↗
PubMed1999

Force generation performance and motor unit recruitment strategy in muscles of contralateral limbs.

The purpose of the present study was to determine whether the motor unit (MU) recruitment strategy of the agonist and antagonist muscles in the dominant arm differs from that in the non-dominant arm. The median frequency (MF) of the power density spectrum (PDS) of the electromyogram (EMG) was used as a tracking parameter to describe the MU recruitment. In 8 subjects the EMG was recorded from the biceps brachii and triceps brachii of each limb during isometric elbow flexion performed in a ramp fashion. Force was increased from 0 to 100% of the maximum voluntary contraction (MVC) in 3 s following a track displayed on an oscilloscope. When comparing the dominant versus non-dominant arm we found no statistical difference in the MU recruitment pattern of the biceps brachii and the triceps. Because the dominant arm was not always the better performing arm, we grouped the data according to the ability of the subjects to track the ramp signal. In this case we found a statistically significant difference between the better and worse performing arm in the full MU recruitment of the biceps. A more precise and accurate control of the increase in force was obtained when the central nervous system selected a slower and prolonged recruitment of MUs in the agonist muscle.

Adult↗
PubMed1999

Cost of walking and locomotor impairment.

The aim of the present study was to evaluate the importance and the necessity of metabolic measurements to quantify locomotor impairment in a clinical context. Oxygen consumption, heart rate, pulmonary ventilation and walking speed were measured during locomotion in 14 normal subjects, used as a control group, and 82 patients with different pathologies [hemiparetic, paraparetic, tetraparetic, orthopaedic and paraplegic patients, who walked using a reciprocating gait orthosis (RGO)]. The subjects were characterized on the basis of a cumulative impairment score (CIS), based on clinical scales commonly used to evaluate impairment and disability in locomotion. Appropriate indices of energy, cardiac and ventilatory costs expressed per metre walked, globally called physiological costs, were obtained. It resulted that the most comfortable speed (MCS) of normal subjects was significantly higher than that of each group of patients. Normal subjects' physiological costs were found to be significantly lower than those of patients who needed either a device or the help of a person to walk. All measured parameters correlated significantly with each other. The MCS was found to be the most correlated parameter with the CIS (r = 0.8), and therefore it must be considered the best single measurement, if only one is to be used. Measurements more precise than MCS, such as the physiological costs, may be necessary in clinical trials.

Adult↗
PubMed1999

Influence of dietary n-3 polyunsaturated fatty acids on plasma lipemic effect of vitamin B6 deficiency.

Since many connections exist between vitamin B6 and lipid metabolism, we aim to investigate the lipemic effect of different dietary intakes of polyunsaturated fatty acids in rats fed a vitamin B6 deficient diet. Diets were either vitamin B6 deficient (-B6) or vitamin B6 sufficient, pair-fed to the deficient group (PF) and ad libitum (N). The diets were combined with normal lipid (LC: soya bean-coconut-palm oils) and fish oil (FO: soya bean-fish oil). The fish oil diet with sufficient vitamin B6 content caused an increase in n-3 long chain polyunsaturated fatty acids and a decrease in arachidonic acid. In the -B6 group fed a normal lipid diet, the arachidonic acid percentage decreased and the linoleic acid percentage increased; in the -B6 group fed fish oil these changes in fatty acid composition, already consequent upon dietary intake of n-3 long chain polyunsaturated fatty acids, did not show further variations. In the dietary condition of vitamin B6 deficiency, plasma cholesterol content increased in rats fed a lipid control diet, whereas no hypocholesterolemic effect was observed in those fed a fish oil diet. Plasma triglyceride contents were not influenced by dietary lipid quality because, in all conditions, the lower food intake of the PF groups caused a decrease and vitamin B6 deficiency caused an elevation in triglyceride contents which reached those of the ad libitum groups. The study highlights the interaction between vitamin B6 and polyunsaturated fatty acids and the opportunity of dietary intake of fish oil to counterbalance some effects of vitamin B6 deficiency.

Animals↗
PubMed1999

A model for analysing the cost of autologous peripheral blood progenitor cell (PBPC) transplantation.

Data from autologous peripheral blood progenitor cell (PBPC) transplant recipients were used for cost analysis and modelling so as to link the main intervention procedures and clinical events to resource use and costs. This cohort consisted of 64 patients from 4 to 62 years old at transplantation (mean, 36.9 years) who underwent a first transplant between August 1994 and May 1997. The main indications for transplantation were non-Hodgkin's lymphomas (47%), multiple myeloma (30%) and Hodgkin's lymphomas (15%). The course of a patient during the whole transplant procedure was modelled using a Markov chain of six states of health: (1) mobilisation and recovery of PBPC; (2) post-mobilisation phase; (3) conditioning and transplant; (4) critical haematological reconstitution; (5) non-critical haematological reconstitution; (6) death. The probability of transition between the different health states, together with the estimated costs, were the input for the Markov model. The model also managed transition probabilities depending both on the current health state and on various demographic, clinical and procedure-related covariates unique to the patient. The expected time spent in each clinical state and the expected total cost were, therefore, estimated. This analysis gave an actual total cost per transplanted patient of $26,600 (95% range: $24,700 to $43,500) while mean duration was 197 days. The expenses for in-hospital stay accounted for 80% of the costs. Both the probability of staying in the different states, and the consequent cost were dependent on the number of CD34-positive cells collected, the phase and the type of the disease, the subset of patients (either children or adults), and the post-transplant G-CSF prophylaxis. The sensitivity of the estimates to alternative assumptions was studied, and the method of comparing alternative future scenarios by the model was explored.

Adolescent↗
PubMed1999

Ambulation training of neurological patients on the treadmill with a new Walking Assistance and Rehabilitation Device (WARD).

STUDY DESIGN: Patients with neurological walking impairment were rehabilitated with a new system, consisting of an apparatus to constantly relieve the body weight and a treadmill: The Walking Assistance and Rehabilitation Device (WARD). Patients were evaluated before and after rehabilitation with clinical scales and physiological measurements. OBJECTIVES: To evaluate the effectiveness of the WARD in improving walking capability in these patients. SETTING: The study was carried out in a clinical environment (IRCCS S. Lucia, Rehabilitation Hospital, Rome, Italy). METHODS: Seven patients (six with spinal cord injuries, one with brain injury) underwent a 1 - 2 month training period with the WARD. During the WARD training the body weight constant unloading (BWCU) applied to the patient through the WARD was regularly evaluated. Oxygen consumption, carbon dioxide production and heart rate were measured in order to obtain energy and cardiac costs of walking. These measurements were carried out while walking with the WARD at an appropriate treadmill speed (ATS) and in the open field at the most comfortable speed (MCS). All measurements, in addition to clinical scores related to the walking capability, were carried out at the beginning of the WARD training period (BWT) and at the end (EWT). At the EWT the patients were tested walking with the WARD observing the same BWT conditions (same ATS and BWCU), referred to as beginning conditions second measurements (BCSM). The relationships between physiological costs and ATS were described through second order polynomial regression curves and studied. RESULTS: Comparing the data obtained at the BWT and EWT, the following results were found significantly different: (1) Clinical scores improved; (2) All patients increased their ATS; (3) The BWCU was reduced; (4) The Walking Energy Cost (WEC) and the Walking Cardiac Cost (WCC) measured when walking with the WARD at the ATS improved in all patients; and (5) The WEC and WCC measured in the open field improved in all patients. The WEC vs ATS curve found at the EWT in the BCSM was found significantly different from the BWT curve, demonstrating a major improvement due to the WARD training. CONCLUSION: Despite some limitations due to sample size and functional ambulation scale, this study has demonstrated that the WARD training is effective in improving the walking capability and efficiency of the patients.

Adult↗
PubMed1999

Hormonal replacement therapy and gynecological cancer.

The problem of quality of life and lifestyle in elderly women is today a very important social problem all over the world but particularly in rich western countries. Life expectancy of the population will be longer and longer in the future and for both females and males the biological involution correlated with the aging process must be delayed. The gonadal hormones stimulate the healthy state of the entire body (heart, skin, brain, bones, urogenital apparatus and so on) and consequently hormonal replacement therapy (HRT) is mandatory. In women the biological clock of menopause allows us to intervene at the right time, with personalized estrogenic, estroprogestinic or estroandrogenic treatments. Health benefits and groundless risks allow today a careful hormonal management even in women treated for gynaecological cancers (breast and endometrium as well).

Aged↗