Low-molecular-weight heparin versus warfarin for secondary prophylaxis of venous thromboembolism: a cost-effectiveness analysis

PURPOSE

To compare the cost effectiveness of low-molecular-weight heparin with that of oral anticoagulants in preventing recurrences after an episode of venous thromboembolism.

METHODS

A decision tree was used to assess the cost and the expected quality-adjusted years of life (QALY) after treatment with either low-molecular-weight heparin or warfarin, based on pooled data from six published trials. Preferences were elicited with a modified time trade-off method in a sample of patients attending an anticoagulation clinic.

RESULTS

Compared with warfarin, low-molecular-weight heparin significantly decreased the rate of minor bleeding (odds ratio [OR] = 0.24; 95% confidence interval [CI]: 0.14 to 0.43) but not recurrent deep vein thromboses (OR = 0.77; 95% CI: 0.43 to 1.35). Patients' preference for warfarin (0.988, on a 0 to 1 scale) was lower than that for low-molecular-weight heparin (0.992), but the difference was not statistically significant. A Monte Carlo analysis estimated that low-molecular-weight heparin saved an average of 13 quality-adjusted days compared with warfarin, at a cost of $6,583 per QALY (95% CI: $5,525 to $7,625) based on costs in Italy and $28,231 per QALY (95% CI: $20,872 to $36,773) based on costs in the United States. When we included rebound recurrences after interruption of therapy, which were more common with low-molecular-weight heparin, treatment with low-molecular-weight heparin cost $53,166 per QALY in Italy and $177,166 per QALY in the United States.

CONCLUSIONS

Low-molecular-weight heparin might be a cost-effective drug for secondary prophylaxis of venous thromboembolism, especially in patients at high risk of recurrence and where the drug's cost is lower. The apparent increase in recurrence after interruption of therapy needs to be investigated more thoroughly before low-molecular-weight heparin can be recommended routinely.

Erythrocyte-mediated delivery of a new homodinucleotide active against human immunodeficiency virus and herpes simplex virus

Monocyte-derived macrophages (MDMs) play a central role in the pathogenesis of infection by human immunodeficiency virus (HIV-1) and represent one of the main reservoirs of the virus in the body. In addition, MDMs can easily be infected by various herpes viruses, including herpes simplex virus type 1 (HSV-1). We have synthesized a new antiviral agent (Bis-PMEA) that consists of two 9-(2-phosphonylmethoxyethyl)adenine (PMEA) molecules bound by a phosphate bridge. This nucleotide analogue, like the parent compound PMEA, has strong and selective activity against HIV-1 and HSV-1. A drug-targeting system previously developed in our laboratory was used for the selective delivery of these drugs to macrophages. Bis-PMEA and PMEA were encapsulated into autologous erythrocytes by a procedure of hypotonic dialysis and isotonic resealing. Loaded erythrocytes were modified to increase their recognition and phagocytosis by human macrophages. By administering Bis-PMEA-loaded erythrocytes to macrophages, 47% of Bis-PMEA and 28% of PMEA was still present 10 days after phagocytosis; in contrast, only 12% of PMEA was found in macrophages receiving PMEA-loaded erythrocytes. Bis-PMEA-loaded erythrocytes were then added to macrophages infected with HIV-1 and HSV-1 and their antiviral activity evaluated. Remarkable protection was obtained against HIV-1 and HSV-1 infection (95 and 85%, respectively). Therefore, Bis-PMEA acts as an efficient antiviral prodrug that, following selective targeting to macrophages by means of loaded erythrocytes, can protect a refractory cell compartment.

fMRI auditory language differences between dyslexic and able reading children

During fMRI, dyslexic and control boys completed auditory language tasks (judging whether pairs of real and/or pseudo words rhymed or were real words) in 30 s 'on' conditions alternating with a 30 s 'off' condition (judging whether tone pairs were same). During phonological judgment, dyslexics had more activity than controls in right than left inferior temporal gyrus and in left precentral gyrus. During lexical judgment, dyslexics were less active than controls in bilateral middle frontal gyrus and more active than controls in left orbital frontal cortex. Individual dyslexics were reliably less active than controls in left insula and left inferior temporal gyrus. Dyslexic and control children differ in brain activation during auditory language processing skills that do not require reading.

Inhibition of HIV-1 replication in macrophages by red blood cell-mediated delivery of a heterodinucleotide of azidothymidine and 9-(R)-2-(phosphono methoxypropyl)adenine

Monocyte-derived macrophages (M/M) are considered important in vivo reservoirs for different kinds of viruses, including HIV. Hence, therapeutic strategies are urgently needed to protect these cells from virus infection or to control viral replication. In this paper, we report the synthesis, target delivery and in vitro efficacy of a new heterodinucleotide (AZTpPMPA), able to inhibit HIV-1 production in human macrophages. AZTpPMPA consists of two established anti-HIV drugs [zidovudine (AZT) and tenofovir (PMPA)] chemically coupled together by a phosphate bridge. This drug is not able to prevent p24 production when administered for 18 h to M/M experimentally infected with HIV-1 Bal (inhibition 27%), but can almost completely suppress virus production when given encapsulated into autologous erythrocytes (inhibition of p24 production 97%). AZTpPMPA is slowly converted to PMPA, AZT monophosphate and AZT (36 h half-life at 37 degrees C) by cell-resident enzymes. Thus AZTpPMPA should be considered a new prodrug of AZT and PMPA that is able to provide stechiometric amounts of both nucleoside analogues to macrophage cells and to overcome the low phosphorylating activity of M/M for AZT and the modest permeability of PMPA.

Erythrocyte-mediated delivery of dexamethasone in patients with chronic obstructive pulmonary disease

Human erythrocytes from ten patients with chronic obstructive pulmonary disease (COPD) were loaded with increasing amounts of dexamethasone 21-phosphate and were re-infused into the original donors. Drug-loaded erythrocytes acted as circulating bioreactors, converting the non-diffusible dexamethasone 21-phosphate into the diffusible dexamethasone. Pharmacokinetic analyses on these patients showed that a single administration of drug-loaded erythrocytes was able to maintain detectable dexamethasone concentrations in blood for up to seven days. This continuous release of dexamethasone was paralleled by the suspension of beta2-agonist and oral corticosteroid treatments by all of the patients. Thus dexamethasone 21-phosphate-loaded erythrocytes are safe carriers for corticosteroid analogues and are a useful alternative to frequent oral or inhaled drugs in elderly patients with COPD.

Comparison of fMRI and PEPSI during language processing in children

The present study explored the correlation between lactate as detected by MR spectroscopy (MRS) and blood oxygenation level dependent (BOLD) responses in male children during auditory-based language tasks. All subjects (N = 8) participated in one proton echo planar spectroscopic imaging (PEPSI) and one functional magnetic resonance imaging (fMRI) session that required phonological and lexical judgments to aurally presented stimuli. Valid PEPSI data was limited in the frontal areas of the brain due to the magnetic susceptibility of the eye orbits and frontal sinuses. Findings from the remainder of the brain indicate that subjects show a significant consistency across imaging techniques in the left temporal area during the lexical task, but not in any other measurable area or during the phonological task. Magn Reson Med 45:217-225, 2001.

Effects of a phonologically driven treatment for dyslexia on lactate levels measured by proton MR spectroscopic imaging

BACKGROUND AND PURPOSE

Dyslexia is a language disorder in which reading ability is compromised because of poor phonologic skills. The purpose of this study was to measure the effect of a phonologically driven treatment for dyslexia on brain lactate response to language stimulation as measured by proton MR spectroscopic imaging.

METHODS

Brain lactate metabolism was measured at two different time points (1 year apart) during four different cognitive tasks (three language tasks and one nonlanguage task) in dyslexic participants (n = 8) and in control participants (n = 7) by using a fast MR spectroscopic imaging technique called proton echo-planar spectroscopic imaging (1 cm3 voxel resolution). The age range for both dyslexic and control participants was 10 to 13 years. Between the first and second imaging sessions, the dyslexic boys participated in an instructional intervention, which was a reading/science workshop.

RESULTS

Before treatment, the dyslexic boys showed significantly greater lactate elevation compared with a control group in the left anterior quadrant (analysis of variance, P = .05) of the brain during a phonologic task. After treatment, however, brain lactate elevation was not significantly different from that of the control group in the left anterior quadrant during the same phonologic task. Behaviorally, the dyslexic participants improved in the phonologic aspects of reading.

CONCLUSION

Instructional intervention that improved phonologic performance in dyslexic boys was associated with changes in brain lactate levels as measured by proton echo-planar spectroscopic imaging.

Biochemical characterization of a hepatitis C virus RNA-dependent RNA polymerase mutant lacking the C-terminal hydrophobic sequence

The RNA-dependent RNA polymerase activity of hepatitis C virus is carried out by the NS5B protein. The full-length protein was previously purified as a non-fusion protein from insect cells infected with a recombinant baculovirus. The characterization is now described of a C-terminal hydrophobic domain deletion mutant of NS5B purified from E. coli. In addition to increased solubility, deletion of this sequence also positively affected the polymerase enzymatic activity. The efficiency of nucleotide polymerization of both the full-length and the C-terminal truncated enzymes were compared on homopolymeric template-primer couples as well as on RNA templates with heteropolymeric sequences. The largest difference in the polymerase activity was observed on the latter. On all the templates, the increased activity could be ascribed, at least in part, to enhanced template turnover of the deletion mutant with respect to the full-length enzyme. The elongation rates of the two enzyme forms were compared under single processive cycle conditions. Under these conditions, both the full-length and the deletion mutant were able to incorporate about 700 nt/min.

Metabolism, mitochondrial uptake and toxicity of 2', 3'-dideoxycytidine

2',3'-Dideoxycytidine (ddCyd) is a prescription anti-retroviral drug that causes mitochondrial toxicity and peripheral neuropathy. ddCyd is actively phosphorylated by cytosolic deoxycytidine kinase and nucleoside (di)phosphate kinase to the 5'-triphosphate derivative. However, 2',3'-dideoxycytidine 5'-diphosphocholine (ddCDP-choline) was also found in human cells incubated with ddCyd. In this paper we show that ddCDP-choline is produced from dideoxyCTP (ddCTP) and phosphocholine by phosphocholine cytidylyltransferase. dCTP and CTP appear to activate this synthesis in a concentration-dependent manner. Although ddCTP and ddCDP-choline can both enter the mitochondria, ddCDP-choline uptake is more efficient than ddCTP uptake. These data suggest that ddCDP- choline is the ddCyd metabolite that is probably responsible for mitochondrial toxicity. The uptake of ddCTP and ddCDP-choline by mitochondria is inhibited by 3.0 mM l-carnitine in the cell-free system investigated; when added to U937 cells grown in the presence of 0.25 microM ddCyd, 3.0 mM l-carnitine partially abrogated the mitochondrial toxicity of ddCyd.

Dyslexic children have abnormal brain lactate response to reading-related language tasks

BACKGROUND AND PURPOSE

Children with dyslexia have difficulty learning to recognize written words owing to subtle deficits in oral language related to processing sounds and accessing words automatically. The purpose of this study was to compare regional changes in brain lactate between dyslexic children and control subjects during oral language activation.

METHODS

Brain lactate metabolism was measured during four different cognitive tasks (three language tasks and one nonlanguage task) in six dyslexic boys and in seven control subjects (age- and IQ-matched right-handed boys who are good readers) using a fast MR spectroscopic imaging technique called proton echo-planar spectroscopic imaging (1-cm3 voxel resolution). The area under the N-acetylaspartate (NAA) and lactate peaks was measured to calculate the lactate/NAA ratio in each voxel.

RESULTS

Dyslexic boys showed a greater area of brain lactate elevation (2.33+/-SE 0.843 voxels) as compared with the control group (0.57+/-SE 0.30 voxels) during a phonological task in the left anterior quadrant. No significant differences were observed in the nonlanguage tasks.

CONCLUSION

Dyslexic and control children differ in brain lactate metabolism when performing language tasks, but do not differ in nonlanguage auditory tasks.

A high-throughput radiometric assay for hepatitis C virus NS3 protease

A novel radiometric in vitro assay for discovery of inhibitors of hepatitis C viral protease activity, suitable for high-throughput screening, was developed. The NS3 protein of hepatitis C virus (HCV) contains a serine protease, whose function is to process the majority of the nonstructural proteins of the viral polyprotein. The viral NS4A protein is a cofactor of NS3 protease activity in the cleavage of NS3-NS4A, NS4A-NS4B, NS4B-NS5A, and NS5A-NS5B junctions. To establish an in vitro assay system we used NS3 proteases from different HCV strains, purified from Escherichia coli and a synthetic radiolabeled peptide substrate that mimics the NS4A-NS4B junction. Upon incubation with the enzyme the substrate was separated from the radiolabeled cleavage product by addition of an ion exchange resin. The assay was performed in a microtiter plate format and offered the potential for assaying numerous samples using a laboratory robot. Taking advantage of these features, we used the assay to optimize reaction conditions by simultaneously varying different buffer components. We showed that physicochemical conditions affect NS3 protease activity in a strain-specific way. Furthermore, the sensitivity of the assay makes it suitable for detection and detailed mechanistic characterization of inhibitors with low-nanomolar affinities for the HCV serine protease.

Cerebral N-acetylaspartate is low in patients with multiple sclerosis and abnormal visual evoked potentials

PURPOSE

Our purpose was to compare cerebral proton MR metabolite changes in patients with multiple sclerosis (MS) and abnormal visual evoked potentials (VEPs) with those in MS patients with normal VEPs.

METHODS

Seventeen subjects with clinically definite MS were studied with VEPs and MR spectroscopic imaging. Proton MR metabolites were measured using a fast spectroscopic imaging technique called proton echo-planar spectroscopic imaging (PEPSI). Kurtzke's Expanded Disability Status Scale (EDSS) score was also ascertained for each subject to obtain a clinical rating. Twelve regions of interest within the visual pathway of the cerebrum were evaluated for levels of N-acetylaspartate (NAA), choline, creatine, and the presence or absence of MR-detectable lesions.

RESULTS

PEPSI NAA values (water-normalized, CSF-corrected) were significantly lower in MS subjects with abnormal VEPs than in subjects with normal VEPs. MR-detectable lesion fractions and EDSS scores were also significantly different between the two VEP groups, but NAA comparison had a P value 100 times less than either of these measures.

CONCLUSION

In patients with MS, NAA measurements in the optic pathways of the brain were sensitive to VEP abnormalities. NAA was more sensitive to VEP changes than were choline, creatine, MR-detectable lesions, and EDSS score.

Functional MR spectroscopy of the auditory cortex in healthy subjects and patients with sudden hearing loss

PURPOSE

To use MR spectroscopy to study the biochemical changes produced by auditory stimuli in patients with sudden sensorineural hearing loss and to compare these findings with the biochemical changes seen in healthy volunteers.

METHODS

Single-voxel MR spectroscopy was used to study biochemical changes in the auditory cortex in 11 control subjects and 19 patients with sudden sensorineural hearing loss. MR spectroscopic signals were measured during three different sound conditions (scanner noise, music, and sirens).

RESULTS

A lower MR spectroscopic lactate signal was observed in control subjects during the music stimulus than during the other sound conditions. This music-induced lactate change was not observed in patients with hearing loss. The other proton metabolites (choline, creatine, N-acetylaspartate [NAA]) remained stable during the different auditory stimuli. However, the NAA/creatine ratio was higher in the auditory cortex of patients than in the control subjects, and was not dependent on the sound condition.

CONCLUSION

The detection of stimulus-induced and stable biochemical MR spectroscopic changes in patients with hearing loss may be useful in assessing disease activity.

Engineering human interleukin-6 to obtain variants with strongly enhanced bioactivity

Interleukin-6 (IL-6) triggers the formation of a high affinity receptor complex with the ligand binding subunit IL-6Ralpha and the signal transducing chain gp130. Since the intracytoplasmic region of the IL-6Ralpha does not contribute to signaling, soluble forms of the extracytoplasmic domain (sIL-6Ralpha), potentiate IL-6 bioactivity and induce a cytokine-responsive status in cells expressing gp130 only. This observation, together with the detection of high levels of circulating soluble human IL-6Ralpha (shIL-6Ralpha) in sera, suggests that the hIL-6-shIL-6Ralpha complex is an alternative form of the cytokine. Here we describe the generation of human IL-6 (hIL-6) variants with strongly enhanced shIL-6Ralpha binding activity and bioactivity. Homology modeling and site-directed mutagenesis of hIL-6 suggested that the binding interface for hIL-6Ralpha is constituted by the C-terminal portion of the D-helix and residues contained in the AB loop. Four libraries of hIL-6 mutants were generated by each time fully randomizing four different amino acids in the predicted AB loop. These libraries were displayed monovalently on filamentous phage surface and sorted separately for binding to immobilized shIL-6Ralpha. Mutants were selected which, when expressed as soluble proteins, showed a 10- to 40-fold improvement in shIL-6Ralpha binding; a further increase (up to 70-fold) was achieved by combining variants isolated from different libraries. Interestingly, high affinity hIL-6 variants show strongly enhanced bioactivity on cells expressing gp13O in the presence of shIL-6Ralpha at concentrations similar to those normally found in human sera.

P-selectin and von Willebrand factor in bovine mesenteric lymphatics: an immunofluorescent study

P-selectin (PADGEM, GMP-140, CD62) is an integral membrane protein specific to alpha granules of platelets and Weibel-Palade bodies of blood vascular endothelial cells. The presence in lymphatic endothelial cells of numerous Weibel-Palade bodies and their positivity to immunocytochemical reaction for von Willebrand factor have previously been characterized and described. Because von Willebrand factor and P-selectin codistribute in Weibel-Palade bodies of blood vascular endothelial cells we investigated the presence of both P-selectin and von Willebrand factor in lymphatic endothelium. Lymphatic vessels expressed positive reaction to immunocytochemical assay thereby demonstrating the presence of P-selectin in the endothelium. Distribution and intensity of the reaction were similar to those observed in bovine blood vascular endothelium.

[Surgical treatment of diverticular disease of the colon. Our experience in the last decade]

The authors analyse their personal experience of diverticular disease of the colon and, comparing it with that of other authors, draw attention to some fundamental data relating to the type of management chosen. Having underlined the high incidence of disease in relation changed living conditions, the authors point out that this pathology is becoming more frequent as a result of the increased average age and that subacute and acute clinical manifestations of the disease are also more common-place. Attention has often been drawn to the presence of non-evolved phlogistic symptoms which it is possible to treat medically thus enabling the operation to be postponed in some cases to a time which is more convenient for the patient, whereas in other cases it has resulted in the remission of symptoms. Surgical therapy need not be used in "silent" cases, but is obligatory in recurring or complicated forms. The authors also affirm that surgery is not burdened by particular postoperative complications which, if present, are linked essentially to peritonitis due to perforation or to other associated pathologies. The use of mechanical staplers has also restricted the number of derivative operations and those performed in several stages.

Elevated urinary excretion of endothelins in streptozotocin diabetic rats

Endothelin-1,2 urinary excretion, has been determined in control and streptozotocin diabetic rats at different times after diabetes induction. Diabetic rats showed increased urinary excretion of endothelins as compared to control rats, already three days after diabetes induction and up to 20 weeks.

[Aberrant pancreas: description of a clinical case and review of the literature]

Aberrant pancreas is a rare finding pathology. Authors reviewed this problem after their personal observation of a specific case, pointing out the behaviour of the disease, particularly the difficult for a careful preoperative diagnosis. They also point out the necessity to make a diagnosis of "suspect" in presence of a symptomatology with the referred characters and when there aren't instrumental findings for evident pathologies.

Acetyl-L-carnitine effect on nerve conduction velocity in streptozotocin-diabetic rats

Measurement of nerve conduction velocity (NCV) is a useful and sensitive tool for evaluating diabetes related neurological dysfunctions. The method used allows to monitor the parameter at different times in the same group of rats, so that it is possible to observe simultaneously the development of the damage in time, and to evaluate the improvement related to the treatment. The repeated oral treatment with acetyl-L-carnitine (ALC, CAS 5080-50-2) 250 mg/kg caused an improvement in NCV of the diabetic rats; the effect was higher when the treatment started early with respect to the diabetes induction. The improvement in NCV was constant in time and comparable from 2 to 6 weeks of the treatment. In conclusion, oral treatment with ALC was able to normalize the impairment of NCV in streptozotocin rats, the effect being constant in time from 2 to 6 weeks of treatment and up to 8 weeks after induction when administration started in early stage of diabetes (2-3 weeks after induction); however, at this time the NCV is already significantly decreased.

Identification of the major degradation products of 4-methoxy-2-(3-phenyl-2-propynyl)phenol formed by exposure to air and light

Exposure of 4-methoxy-2-(3-phenyl-2-propynyl)phenol (CO/1828) to air and light (accelerated by temperature) yields 1-(2-hydroxy-5- methoxyphenyl)-3-phenylpropynone as the major degradation product. With extraction, this product rapidly degrades to 5-methoxyaurone and 6-methoxyflavone. In addition, a mixture of dimeric and heterodimeric compounds that are not fully identified was observed. These results indicate the formation of a reactive ortho-quinone methide as an unstable intermediate. This hypothesis is supported by evidence that the aurone slowly isomerizes into the flavone in control samples. Identification of compounds was accomplished with mass spectrometry, nuclear magnetic resonance spectrometry, UV-high-performance liquid chromatography, and comparison with authentic samples.

Metabolism of (-)-6(S)-hydroxy-4(R)-(1-hydroxy-1-methylethyl)-1- cyclohexene-1-ethanol in rat and dog

1. The metabolism of a new mucoactive drug, chemically (-)-6(S)-hydroxy-4(R)- (1-hydroxy-1-methylethyl)-1-cyclohexene-1-ethanol (CO/1408), has been studied in rat and dog after a single oral dose; eight metabolites were identified. 2. Oxidation of the primary and secondary alcohol groups, hydroxylation in allylic positions and conjugation with glucuronic acid occurred in both species. Products of oxidation on the double bond have not been identified. 3. Using reversed-phase h.p.l.c. and beta-cyclodextrin in the eluent it was found that the glucuronide metabolites varied with species and with the biological fluid examined.

[Stapler reconstruction after total gastrectomy contrasted with manual anastomosis]

A personal series (1985-1987) of 22 cases of total gastrectomy for cancer is analysed, a comparison being made between 11 cases treated with manual anastomosis and 11 reconstructed using a stapler. The advantages and disadvantages of the various techniques are examined and although no substantial difference is noted between the two reconstructive modalities, at least as regards morbidity and mortality, stress is laid on the unquestionable advantages of mechanical staplers. These are essentially speed of execution, suture perfection and excellent long-term results.