Structural and rheological properties of chitosan semi-interpenetrated networks.

The local structure and the viscoelastic properties of semi-interpenetrated biopolymer networks based on cross-linked chitosan and poly(ethylene oxide) (PEO) were investigated by Small Angle Neutron Scattering and rheological measurements. The specific viscosity and the entanglement concentration of chitosan were first determined, respectively, by capillary viscosimetry and steady-state shear rheology experiments performed at different polymer concentrations. Mechanical spectroscopy was then used to study the gelation process of chitosan/PEO semi-interpenetrated networks. By fitting the frequency dependence of the elastic and loss moduli with extended relations of relaxation shear modulus around the sol-gel transition, it was shown that the addition of PEO chains had a significant effect on the viscoelastic properties of aqueous chitosan networks but no effect on the gelation time. The improvement of mechanical properties was in accordance with the correlation length decrease deduced from Small Angle Neutron Scattering experiments.

Endoluminal repair of a pseudoaneurysm in a patient with cryopreserved arterial allograft of the iliac vessel.

Prosthetic infection is one of the most serious complications of vascular surgery, and its treatment remains a surgical challenge. Good results have been reported using in situ replacement with arterial allografts, but late degeneration of the graft itself may necessitate further repair. We report a case of rupture and pseudoaneurysm formation of an iliac artery homograft urgently treated by endoluminal grafting with complete and immediate exclusion of the sac without complications. At 6-month follow-up angio-computed tomography showed patency of the vascular stent graft without leak evidence. Two years and 6 months after the procedure, the patient is well and alive.

Endovascular repair of a ruptured giant popliteal artery aneurysm.

An 88-year-old woman with hypertension, chronic vein insufficiency, and repeated cellulites in the right lower extremity was admitted to our hospital with a new episode of right leg inflammation and edema associated with fever and leukocytosis. Due to unilateral enlargement of the leg and D-simer levels of 1000 microg/mL, a concomitant deep venous thrombosis was suspected and ultrasonography was performed. Color duplex-scanning found normal flow in the right deep leg veins but revealed an 11-cm-diameter popliteal artery aneurysm. A computed tomography scan confirmed the diagnosis and revealed a large perianeurysmal hematoma, and angiography provided evidence of perianeurysmal bleeding. The patient was unfit for open surgery, so an endovascular approach under local anesthesia was elected. The aneurysm was successfully excluded with an endograft, and 15 months after surgery, the patient is alive and had an uneventful postoperative course.

Surgical treatment of arterial ischemia associated with the use of the angioseal vascular closure device.

BACKGROUND: Despite the theoretical effectiveness of the Angio-Seal closure device to control bleeding after arterial puncture it can increase the risk of ischemia. OBJECTIVES: To describe arterial lesions caused by the device, surgical techniques needed to repair those lesions and surgical outcome in patients who underwent surgery for arterial ischemia after heart catheterization. PATIENTS AND METHODS: Seven patients underwent surgery over a period of 12 months at our institution. Five patients underwent emergency surgery and two a delayed procedure. The cause of ischemia was dissection of an atheroma plaque at the puncture site in four cases, dissection of the superficial femoral artery in one case, thrombosis of the common femoral artery in one case, and plication of the posterior arterial wall in one case. Arterial repair in these patients required the insertion of a vascular graft in three cases, endarterectomy plus angioplasty in two cases, endarterectomy plus graft interposition plus thrombectomy of the superficial femoral artery in one case and endarterectomy plus femoropopliteal bypass in one case. RESULTS: Treatment was successful in all patients. Mean follow up was 7.6 months (range 5-11 months). During the study period one patient died due to cardiopathy. No patients had to be re-operated and no limb losses were recorded. All the patients were asymptomatic from a vascular point of view with normal active lives for their age. CONCLUSIONS: Surgical repair is effective, although, generally, it is not restricted to a simple thrombectomy, requiring the use of different arterial repair techniques.

Presence of transcription regulatory elements within an intron of the virus-inducible murine TIMP gene.

The expression of the gene for the murine tissue inhibitor of metalloproteinases (TIMP) is induced in response to viruses, growth factors, and phorbol esters. In this report we show that the accumulation of TIMP mRNA after Newcastle disease virus induction is caused by transcriptional activation of the gene. Comparison of the sequences of cDNA and genomic clones along with RNase protection and primer extension analyses revealed that the murine TIMP gene possesses multiple cap sites and that the exon 1 consists exclusively of 5'-noncoding sequences. We observed that DNA regions analogous to those found upstream of the virus-inducible interferon genes are present within intron 1 of the TIMP gene. To investigate the possible role of TIMP intron 1 in gene expression, we used a functional assay based on the transfection of plasmids in which the DNA segment to be tested is placed in proximity to a marker gene driven by the heterologous herpes simplex virus thymidine kinase promoter. Our results indicate that TIMP intron 1 contains DNA sequence elements capable of modulating the activity of a heterologous promoter in two different ways: (i) by enhancing constitutive expression and (ii) by conferring virus inducibility. These results suggest that intron 1 may be involved in the transcriptional regulation of TIMP gene expression.

Decreased expression of tissue inhibitor of metalloproteinases in metastatic tumor cells leading to increased levels of collagenase activity.

We have examined the expression of murine tissue inhibitor of metalloproteinases (TIMP) in nonmetastatic and metastatic cell lines derived from SP1 murine mammary adenocarcinoma cells. We observed decreased levels of TIMP mRNA and activity in metastatic cells as compared to their nonmetastatic equivalents in the absence of fetal bovine serum. Lower levels of TIMP mRNA correlated to decreased levels of transcription of the TIMP gene. Net collagenase activity was higher in metastatic cells, but metastatic and nonmetastatic cells secreted similar levels of total collagenase (mainly type IV). This suggests that decreased TIMP gene expression results in increased net collagenase activity in malignant cells.

Basal expression of the gene (TIMP) encoding the murine tissue inhibitor of metalloproteinases is mediated through AP1- and CCAAT-binding factors.

In cultured murine fibroblasts, the TIMP gene (encoding tissue inhibitor of metalloproteinases) is transcribed constitutively, although at low levels. We have used a cell-free system in which nuclear extracts prepared from murine L cells support transcription from TIMP DNA templates in vitro. This system was used to study the role of cis-acting DNA sequences in the constitutive expression of TIMP. Sequences important for expression are located both 5' and 3' (in intron 1) to the major transcription start point and are required to obtain detectable levels of transcription. These regions are specifically recognized by murine nuclear factors and contain DNA motifs whose sequences closely resemble binding sites for known transcriptional activators. In particular, the data strongly suggest a role for CCAAT-binding factor(s) and AP1-binding factors in the basal transcription of TIMP.

Negative, psychoticism, and disorganized dimensions in patients with familial schizophrenia or bipolar disorder: continuity and discontinuity between the major psychoses.

OBJECTIVE: This study aimed to answer the following questions: 1) Can we reliably measure the psychopathologic dimensions of schizophrenia by using a lifetime frame and by rating acute and interepisode periods separately? 2) Can we reproduce in subjects with familial schizophrenia the characteristic three-factor structure of schizophrenic symptoms that has been found previously in general groups of schizophrenic patients? 3) Is the factor structure also present in familial bipolar disorder? METHOD: Lifetime measures of psychotic symptoms were taken through a slightly modified version of the Comprehensive Assessment of Symptoms and History for 138 patients with highly familial DSM-III-R schizophrenia (N = 51), bipolar disorder (N = 44), or spectrum disorders (N = 43). Symptoms were rated separately in the acute episodes and in the stabilized interepisode intervals across the patients' lives. RESULTS: A satisfactory level of reliability was obtained. In this highly familial study group, the positive/negative factorial distinction was replicated, as was a three-factor model similar to that observed in prior general groups of schizophrenic patients. These factors were also present in bipolar affective disorder. The negative, psychoticism, and disorganized factor model applied more to the acute phase of illness than to the stabilized state. CONCLUSIONS: These findings offer an empirical basis for testing biological or genetic variables in relation to negative/positive symptom dimensions, rather than diagnoses. Observations of a shared structure for schizophrenia and bipolar disorder suggest some continuity in the causes of these disorders.

Clinical and methodological factors related to reliability of the best-estimate diagnostic procedure.

OBJECTIVE: The reliability and accuracy of the best-estimate diagnostic procedure were examined, and factors associated with reliability were determined. METHOD: The subjects were 134 members of large multigenerational pedigrees densely affected by bipolar disorders or schizophrenia. Three best-estimate diagnoses were derived: first, by a research psychiatrist and research assistant unblind to the relatives' diagnoses; second, by two blind independent psychiatrists; third, by a panel of four blind psychiatrists. The subjects were characterized on several clinical and methodological variables, which were used to compare the agreements of two types of best-estimate diagnoses with the disagreements. RESULTS: There was satisfactory agreement between the unblind and blind consensus best-estimate diagnoses and between the two blind independent psychiatrists. Latent class analyses revealed that limited sensitivity was the main source of imperfect reliability. Confusability analyses revealed that the most problematic diagnostic distinctions involved schizoaffective disorder, which was confused with schizophrenia, bipolar I disorder, and schizophreniform disorder. Blindness significantly affected diagnostic outcome in latent class analyses. Moreover, for diagnostic disagreements, unblind diagnoses had greater continuity with the most predominant diagnosis in the pedigree than did blind diagnoses. Diagnostic disagreements were associated with the presence of mixed affective and psychotic symptoms, less diagnostic certainty, and shorter duration of illness. CONCLUSIONS: These results suggest that it is possible to identify cases that are more likely to lead to diagnostic disagreements in family and epidemiological studies and that blind diagnoses may help to prevent false positive diagnoses, which may be particularly detrimental to genetic linkage analyses.

Apoptosis induced by hydrogen peroxide is mediated by decreased superoxide anion concentration and reduction of intracellular milieu.

Hydrogen peroxide (H2O2) is considered to be a mediator of apoptotic cell death but the mechanism by which it induces apoptosis is unclear. Here, we show that cells undergoing apoptosis from exposure to H2O2 display a significant decrease in intracellular concentration of superoxide (O2-) which is associated with a reduction of the intracellular milieu, as measured by an increase in the GSH/GSSG ratio and a decrease in intracellular pH. The notion that a decrease in intracellular O2- concentration triggers apoptosis is supported by the observation that H2O2-mediated apoptosis could be retarded in cells in which the intracellular O2- concentration is maintained at or above the cellular baseline level by inhibition of the major O2- scavenger superoxide dismutase (Cu/Zn SOD). Taken together, our observations indicate that a decrease in the intracellular O2- concentration, reduction and acidification of the intracellular milieu constitute a signal for H2O2-mediated apoptosis, thereby inducing a reductive as opposed to an oxidative stress.

Activity and mRNA abundance of Delta-5 and Delta-6 fatty acid desaturases in two human cell lines.

We analyzed fatty acid biosynthesis in Chang and ZR-75-1 cells. Both cell lines could desaturate and further elongate substrates for Delta-5 desaturase. ZR-75-1 but not Chang cells showed Delta-6 desaturation of 18:2n-6, 18:3n-3, 24:4n-6 and 24:5n-3. In both cell lines, the mRNA abundance can be related to Delta-5 or Delta-6 fatty acid desaturase activities. These results suggest that desaturase genes could have, at least in part, independent control mechanisms and that Delta-6 desaturase impairment is not specific to any particular step of the fatty acid metabolic pathways, which may diminish the rationale for the existence of at least two distinct enzymes.

6p24-22 region and major psychoses in the Eastern Quebec population. Le Groupe IREP.

Recent reports of a linkage trend in 6p24-22 for schizophrenia (SZ), in different samples, were tempered by the concurrent evidence of negative reports in other samples. In the studies showing positive results, different definitions of affection and a wide spectrum of diagnoses were used. Our objectives were not only to test for linkage at 6p24-22 in the Eastern Quebec population, but also to test whether this putative vulnerability locus was either selectively linked to schizophrenia (SZ), or to bipolar disorder (BP), or to both major psychoses. Parametric and nonparametric linkage analyses with 12 microsatellite markers in 6p24-p22 were performed on a sample of 18 large multigenerational pedigrees (N = 354) either affected by SZ, or by BP, or equally affected by both major psychoses (i.e., mixed pedigrees). Three affection definitions were usually tested in our program: one on schizophrenia (SZ), one on bipolar disorder (BP), and one that comprised SZ and BP under the hypothesis of a susceptibility locus common to both in major psychoses (common locus, CL). The results of parametric analyses did not support a major gene hypothesis. However, in one large mixed pedigree (#151), we observed with the common locus phenotype (CL) lod scores of 2.49 and 2.15, respectively, at the D6S296 and D6S277 loci under a dominant model. Our data suggest the presence of a potential vulnerability locus at 6p24-22 that could be related to both schizophrenia and bipolar affective disorder. These results may be seen as congruent with former studies that used schizoaffective as well as schizophrenia diagnoses as entry criteria for the affected families, and used an affection definition that comprised affective psychoses as well as schizophrenia.

Changes in chromatin conformation regulate the 5-lipoxygenase gene expression during differentiation of HL60 cells.

The HL60 cell line does not express the 5-lipoxygenase gene prior to differentiation with various agents. In this paper we have shown by DNase I sensitivity that the chromatin conformation of the 5-lipoxygenase gene changes following differentiation of HL60 cells with dimethyl sulfoxide (DMSO). Moreover, run-on analysis suggests that transcription of the 5-lipoxygenase gene is enhanced after differentiation. We proposed that the chromatin conformation represses the expression of the 5-lipoxygenase gene in HL60 cell line and that differentiation of these cells with DMSO changes the chromatin conformation, which allows the expression of the 5-lipoxygenase gene. The HeLa cells which, like the HL60 cells, do not express the 5-lipoxygenase, were insensitive to DNase I treatment. These results suggest that chromatin structure might represent a form of regulation for the 5-lipoxygenase gene.

Highly purified guinea pig type II pneumocytes have the leukotriene A4 hydrolase but do not express 5-lipoxygenase activity.

Guinea pig lung cells have been obtained by enzymatic digestion of lung tissue and type II pneumocytes have been purified by centrifugal elutriation and adherence on Petri dishes coated with guinea pig IgG. The cells have been characterized by histochemical staining of alkaline phosphatase and by electron microscopy. Arachidonic acid metabolism was studied by incubating purified type II pneumocytes with exogenous arachidonic acid in the presence or absence of calcium ionophore A23187 or with leukotriene A4. The reverse phase high performance liquid chromatography profiles of cells stimulated with calcium ionophore and/or arachidonic acid did not show peaks co-eluting with authentic leukotrienes, which suggested that these cells do not express 5-lipoxygenase activity. On the other hand, type II pneumocytes converted exogenous leukotriene A4 into leukotriene B4; a small amount of peptido-leukotrienes, accounting for less than 5% of total leukotrienes produced, was also detected. It is suggested that transcellular metabolism of leukotriene A4 between type II pneumocytes and other lung cells containing the 5-lipoxygenase may contribute to the previously reported LTB4 production by guinea pig lungs. The type II pneumocyte purification technique described represents a useful alternative to cell culture for studying arachidonic acid metabolism and other cell functions.

Rising tumour marker during chemotherapy in a patient with an extra-gonadal germ cell tumour--prolonged survival after tumour excision.

A 28-year-old white male presented with a palpable abdominal mass and a grossly elevated beta human chorionic gonadotrophin. He refused investigations to establish the pathology and was treated with cisplatin combination chemotherapy. After an initial fall in his marker, it rose while he was on chemotherapy. The tumour was resected which confirmed the presence of a retroperitoneal germ cell tumour (extra-gonadal). He received further adjuvant chemotherapy and is subsequently clear of disease after being off treatment for more than 5 years. Total resection is not usually considered possible in patients with persistent positive markers after induction chemotherapy. This case shows that surgery should be considered as the results of salvage chemotherapy are poor in these patients.

Recurrence of Listeria monocytogenes meningitis.

A case of Listeria monocytogenes meningitis in a 3-year-old boy which relapsed after chloramphenicol treatment is described. The patient was subsequently successfully treated with ampicillin and gentamicin and made a complete recovery. In vitro studies confirmed the inadequacy of chloramphenicol therapy. The value of combination therapy, as evidenced by chessboard and killing-curve techniques with the strain, is discussed.

Local rheological probes for complex fluids: application to Laponite suspensions.

We present an experimental method allowing a direct measurement of the local rheological behavior of complex fluids. A magnetic probe is inserted into the bulk of the fluid and submitted to a controlled magnetic force or torque, which induces a mechanical perturbation of the fluid. The geometry of the perturbation can be varied using two kinds of probes: a magnetic bead submitted to a homogeneous magnetic force in one direction, and a magnetic needle that can turn inside the material under the effect of an applied magnetic torque. Two complex viscoelastic fluids are investigated. First, a surfactant solution, which has a linear mechanical behavior in the range of the applied stresses, is used to test and validate the experimental methodology. We then use the local probes to investigate a Laponite colloidal suspension, which exhibits nonlinear behavior such as thixotropy, shear thinning, and aging. In this latter fluid, we find an exponential growth of the rheological relaxation time versus the system age, a power-law dependence of the fluid viscosity on the applied stress, and a dynamical yield stress which saturates with the fluid aging time.

Rotational magnetic particles microrheology: the Maxwellian case.

An experimental method based on the rotational dynamics of a magnetic probe is reported to measure the local viscoelasticity of soft materials on microscopic scales. The technique is based on the alignment of dipolar chains of submicrometer magnetic particles in the direction of an applied magnetic field. On one hand, light scattering is used to detect the chains' oscillations over a 0.001-100 Hz frequency range when submitted to an oscillating magnetic field and leads to global microrheological measurements. On the other hand, the chains' rotation toward a permanent magnetic field is observed with a microscope, allowing a local determination of viscoelastic properties on the scale of the chains of particles. We demonstrate the accuracy of both assays with a micellar Maxwellian solution and validate theoretical predictions.

Rheological study of the sol-gel transition in silica alkoxides.

The sol-gel transition of the system tetramethylorthosilicate-water-methanol under basic conditions has been studied by rheological measurements. The gelation time t(g) has been determined from the measurements of the elastic G' and viscous G'' moduli as a function of time at different frequencies according to Winter's criterion. At gelation time the frequency dependence of both moduli follows a power law with an exponent related to the fractal dimension of the network structure. Different initial monomer concentrations, hydrolysis molar ratios, and temperatures are studied. The decrease of the gelation time with an increase of initial monomer concentration or hydrolysis molar ratio is well-described by a power law. An apparent activation energy is deduced from the temperature dependence of gelation time.