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Biomedical subjects

G Michel

Publications and source records attributed to G Michel.

At least 217 records · Page 12Linked to original sources

In vitro attachment of Streptococcus sanguis to the dentin of the root canal.

The adhesion of a strain of Streptococcus sanguis (NCTC 7863) to the root canal dentin of bovine incisors was evaluated. Samples (104) were prepared and smear layer was created on the root canal surface with a tungsten carbide bur. The samples were divided into four groups, one of them serving as a control sample and the other three each receiving a different treatment: 6% citric acid for 2 min (group 3), 6% citric acid for 2 min + 6.25% sodium hypochlorite for 1 min (group 2), 6% citric acid for 10 min (group 4). After sterilization, they were incubated, and adhesion was assessed by direct examination using a scanning electron microscope. The use of irrigation solutions significantly reduced the adhesion in the latter two groups only, with a reduction of 15% (group 2) and 18.7% (group 4) in the number of bacteria.

Animals↗

An animal model for antilentiviral therapy: effect of zidovudine on viral load during acute infection after exposure of macaques to simian immunodeficiency virus.

We analyzed the kinetics of the virological and immunological events that occurred in four AZT-treated cynomolgus macaques during the acute infection that followed their exposure to the simian immunodeficiency virus (SIVmac251) grown on monkey PBMCs in a cell-free stock solution. These events included changes in the CD4+ and CD8+ T lymphocyte subsets, p27 antigenemia, infectious serum virus, and cell-associated virus loads. The kinetics of these changes proved strikingly similar to those reported in human HIV-1 infection. Four other SIV-exposed macaques were treated with placebo instead of AZT. We demonstrated that AZT does not prevent SIV infection, even when administered before SIV inoculation. However, the peaks of p27 antigenemia and of serum and cellular viremia were significantly smaller and occurred significantly later in the monkeys given AZT than in those given placebo.

Acquired Immunodeficiency Syndrome↗

Weekly carboplatin and VM-26 for elderly patients with small-cell lung cancer.

BACKGROUND: Elderly patients are excluded from chemotherapy trials, even though they represent 25% of those with small cell lung cancer. An effective chemotherapy regimen with limited toxicity should be developed with the aim not only of increasing the survival of these patients, but also of improving their quality of life and their independence. PATIENTS AND METHODS: Twenty-four patients with a median age of 72 years and small-cell lung cancer (SCLC) were included in the trial. Chemotherapy consisted of a weekly intravenous regimen of Carboplatin 80 mg/m2 and Teniposide 80 mg/m2 administered on an outpatient basis. RESULTS: Eight patients had limited and 16 extensive disease. After a median of 12 chemotherapy courses (2-31) the overall response rate was 66.7% (95% Cl: 44.7-84.4), with 5 patients in complete and 11 in partial remission. The median overall survival was 33 weeks, with 4 patients alive at more than one year. Improvement of symptoms occurred in 86% of patients. Toxicity, mainly hematological, was moderate. CONCLUSIONS: Weekly Carboplatin and VM-26 is an effective and non-toxic regimen for elderly patients, leading to results similar to those obtained with a more intensive regimen in a younger age group.

Aged↗

Cytokine system as potential target for antipsoriatic therapy.

Cytokines are produced by a variety of cells and have numerous of overlapping activities. There is increasing evidence that cytokines play a crucial role in the pathogenesis of psoriasis and of other dermatologic diseases. This review summarizes current knowledge as to how the altered cytokine network is involved in the accumulation of inflammatory cells in lesional skin, and how the cytokines are involved in epidermal hyperproliferation. The actions of the most important therapeutic compounds, such as corticosteroids, dithranol, cyclosporine, retinoids, vitamin D3 analogues and ultraviolet radiation, on the cytokine system are also discussed. Consideration is given as to how the effects on the production of cytokines and/or cytokine receptors contribute to their therapeutic action.

Anthralin↗

Role of interleukin-8 receptor in skin.

Interleukin-8 (IL-8) is a potent chemotactic and proinflammatory cytokine, produced in the skin by a variety of cells in response to inflammatory stimuli. Recent studies suggest that in addition to its potent actions on leukocytes, IL-8 exerts a direct influence on several functions of human epidermal cells such as chemotaxis, Candida albicans killing activity or proliferation. The effects of IL-8 are mediated by binding to two types of specific high-affinity receptors which contain seven transmembrane domains typical of guanine nucleotide binding protein (G protein)-coupled receptors. In the skin, a broad spectrum of cells such as neutrophils, T lymphocytes, mast cells, dermal macrophages, endothelial cells and keratinocytes possess binding sites for IL-8. Recently, increased expression of epidermal IL-8 receptors has been observed in psoriasis an inflammatory and hyperproliferative skin disease. Since the effects of IL-8 may be modulated at the receptor level, the pharmacological manipulation of the IL-8 receptor may prove an important target for the therapy of skin diseases with increased IL-8 levels.

Binding Sites↗

An in vitro mouth model to test antiplaque agents: preliminary studies using a toothpaste containing chlorhexidine.

The development of an in vitro model simulating the oral cavity has allowed the antiplaque activity of a toothpaste containing 0.004% chlorhexidine to be tested. The model is based on the continuous irrigation of bovine tooth samples with artificial saliva. Scanning electron microscopy showed homogeneous colonization of monobacterial plaque by Streptococcus mutans on dental surfaces under these model conditions. The enamel was colonized with regular cell clusters showing a globular appearance. The globules coalesced with increasing plaque thickness. Treatment with toothpaste containing 0.004% chlorhexidine showed a more marked inhibition of bacterial colonization on enamel surfaces than placebo paste lacking this antimicrobial agent. These results indicate that the toothpaste formulation is compatible with chlorhexidine. It is concluded that the in vitro model developed in this study is suitable for the testing of the antiplaque activity of antimicrobial agents, particularly when in a semisolid form such as in a toothpaste.

Animals↗

Allogeneic bone marrow transplantation for children with acute myeloblastic leukemia in first complete remission: impact of conditioning regimen without total-body irradiation--a report from the Société Française de Greffe de Moelle.

PURPOSE: To analyze the French experience of chemotherapeutic preparation before human leukocyte antigen (HLA)-identical bone marrow transplantation (BMT) in children with acute myeloblastic leukemia (AML) in first complete remission (CR). PATIENTS AND METHODS: The data base used for this study was a French BMT registry for childhood AML. Twenty-three children were conditioned with busulfan and 120 mg/kg cyclophosphamide (Bu-Cy 120 group). Nineteen received busulfan and 200 mg/kg cyclophosphamide (Bu-Cy200 group). During the same time period, 32 patients were prepared with total-body irradiation (TBI group) most often in combination with 120 mg/kg of cyclophosphamide. RESULTS: The probability of relapse was 54%, 13%, and 10% for the Bu-Cy120, Bu-Cy200, and TBI groups, respectively (P < .05 in the univariate analysis, log-rank test, 2 df). In the multivariate analysis, a conditioning regimen with Bu-Cy120 was significantly associated with a higher risk of relapse (P = .02; relative risk, 3.62). The probability of transplant-related mortality (TRM) was 0% for Bu-Cy120, 5% for Bu-Cy200, and 10% for TBI. Kaplan-Meier estimations of event-free survival (EFS) were 46% +/- 24%, 82% +/- 18%, and 80% +/- 14%, respectively, for the three groups, with median follow-up durations of 28 months (range, 3 to 78), 31 months (4 to 68), and 48 months (2 to 73). In the multivariate analysis, two factors adversely affected EFS: a conditioning regimen with Bu-Cy120 (P = .07) and a long interval from diagnosis to BMT (> or = 120 days, P = .08). CONCLUSION: Bu-Cy120 is a well-tolerated preparation, but results in a high risk of relapse for children with AML in first CR. This high risk of relapse is not observed when the dose of cyclophosphamide is increased to 200 mg/kg.

Antineoplastic Combined Chemotherapy Protocols↗

Croconazole: a new broad spectrum agent in the treatment of fungal skin infections.

Croconazole hydrochloride (1%) cream is a new antifungal agent for the treatment of dermatomycoses. In vitro, croconazole has a broad spectrum of activity against dermatophytes, moulds, yeasts, dimorphic fungi and some skin-relevant bacteria. Therapeutic results obtained in 277 patients (mean age 43.0 +/- 14.8 years; 158 male and 119 female) who had mycoses at various locations and were treated with 1% croconazole cream are reported. The types of fungal infection in these patients were: pityriasis versicolor (94), candidiasis (43) and trichophytosis (140). One topical application per day was administered for a period of up to three weeks. Clinical improvement and mycology were assessed at one-week intervals, and after a two-week treatment-free follow-up. In all three infection groups the criteria of mycosis, particularly fungal microscopy findings and itching, showed rapid improvement. At the end of the observation period, clinical and mycological cure was observed in the majority of patients. The physicians' global efficacy rating of the medication was "good" or "very good" in 92.6% of the cases with pityriasis versicolor, 97.7% of the patients with candidiasis and 82.9% of the trichophytosis patients. The medication was well tolerated: only one patient reported an adverse reaction (pruritus) at the site of application. It is concluded that croconazole cream is effective and well tolerated in dermatomycoses. The once-a-day use of croconazole cream may be a positive factor in patient compliance.

Adult↗

[Sporocidic activity of sodium hypochlorite and peracetic acid alone or combined against free or fixed spores or on biofilm].

In order to assess the sporocidal activity of chlorine and peracetic acid (PAA), alone and in combination, against a spored biofilm, the biofilms of two species (Bacillus subtilis ATCC 6633 and Bacillus megaterium ATCC 8245) were formed on inert support (tygon). A sporulation kinetic of these bacteria in biofilm was established. Sporocidal properties of chlorine and PAA were compared against free spores, spores fixed by drying and spores in biofilm. The combination of these two products was also tested. Minimal sporocidal concentrations (MSC) of the two products towards free spores were determined (contact time 5 mn). The efficacy of these MSC were evaluated in terms of contact time on adhered spores and on spores in biofilm. Chlorine and PAA exhibited an excellent sporocidal activity. The combination of PAA and chlorine, tested by checkerboard micromethod, was found to be synergistic in case of free or adhered spores. The spored biofilm showed a high resistance. The combination of these two products revealed then only an additive effect.

Bacillus megaterium↗

Effect of iturin A, a lipopeptide from Bacillus subtilis on morphology and ultrastructure of human erythrocytes.

Iturin A, a lipopeptide from Bacillus subtilis, induced morphological modifications of human erythrocytes and a concomitant release of exovesicles. The modifications depended on the lipopeptide concentration and on the incubation time. Crenation of cells occurred while invaginations appeared when the incubation time was increased. This suggested that iturin A was gradually translocated from the outer layer into the inner half of the bilayer. For one lipopeptide concentration, heterogeneity in the form of the erythrocytes was observed which could result from heterogeneity in the self-association of iturin A. The lipid composition of exovesicles was markedly different from that of the native erythrocytes; they were enriched in cholesterol, sphingomyelin and phosphatidylcholine. Freeze-fracture showed that the ultrastructure of the protoplasmic face of the membrane was not modified by iturin A but, when erythrocytes were prefixed with glutaraldehyde prior to iturin A treatment, irregular smooth protuberances appeared with a decrease of intramembranous particles density. These protuberances which covered the complete area of the cell may have been complex associations of iturin A, phospholipids and cholesterol.

Anti-Bacterial Agents↗

Concentration time courses of troponin and myosin subunits after acute myocardial infarction.

BACKGROUND: As a result of the limited sensitivity and specificity of creatine kinase and lactate dehydrogenase (LDH) as well as their isoenzymes, there is increasing interest in the use of cardiac contractile proteins for the diagnosis of acute myocardial infarction (AMI) and myocardial damage. METHODS: This study compared the release of creatine kinase, creatine kinase MB, myoglobin, cardiac troponin I (cTnI), cardiac troponin T (cTnT), cardiac myosin light chain-1 (cMLC-1), and beta-type myosin heavy chains (bMHC) in serial blood samples from 13 patients (10 men, three women; median age 54 years, range 40-74 years) with first-time AMI (11 Q-wave, two non-Q-wave AMI; three anterior and 10 inferior wall AMI). All but one patient received intravenous thrombolytic treatment. RESULTS: Myoglobin was the first marker to increase in blood after AMI and showed the earliest peak levels, whereas bMHC increased latest, showing the latest peak levels. cTnI and cTnT increased significantly earlier than cMLC-1 and bMHC. cTnI and cTnT increased and reached peak levels parallel to each other, but the latter tended to stay increased longer. cTnT time courses were biphasic in the majority of AMI patients, unlike cTnI time courses. cMLC-1 release was mostly biphasic. cMLC-1 allows diagnosis during the acute phase as well as several days after the onset of AMI. The time courses of bMHC were usually monophasic. Its delayed appearance makes it useful for the diagnosis of remote infarction. In contrast to cTnI and cTnT, cMLC-1 and bMHC time courses were not significantly influenced by early reperfusion. CONCLUSION: Our results demonstrate the impact of the intracellular compartmentation of an intramyocardial protein (cytosolic, structurally bound, or structurally bound with soluble pool) on its concentration time course after AMI, particularly on the rapidity of its release.

Adult↗

GOR-antibodies in patients with chronic liver disease and hepatocellular carcinoma.

HCV infection frequently leads to liver cirrhosis and the development of hepatocellular carcinoma, while the mechanisms of carcinogenesis are still unclear. Autoantibodies like antinuclear antibodies have been described to increase and change their specificity in patients with hepatocellular carcinoma. Autoantibodies against GOR, an antigen not encoded by the viral but by the host's genome and overexpressed in tumor cells, are frequently associated with hepatitis C infection, but their significance during the development of hepatocellular carcinoma has not been determined yet. We analysed the frequency of GOR-antibodies in 38 patients with hepatocellular carcinoma on the grounds of liver cirrhosis of different origin, 38 patients with extrahepatic tumors, 24 patients with hepatitis C infection and 30 healthy controls. GOR-antibodies were found to be specifically associated with hepatitis C and were only found in patients with hepatocellular carcinoma if the liver cirrhosis was due to HCV-infection. Patients with extrahepatic tumors with or without liver metastasis had no detectable GOR antibodies, if no HCV infection was present. The determination of antibodies to the autoantigen GOR therefore has no clinical significance in patients with hepatic or extrahepatic tumors not related to HCV infection.

Adolescent↗

Lung toxoplasmosis after HLA mismatched bone marrow transplantation.

We report a clinically isolated toxoplasma pneumonitis in a child treated by HLA haplo-mismatched BMT. Conditioning consisted of TBI, cytarabine and melphalan. The BM graft was T-depleted and the boy received iv moAb antiLFA1 and antiCD2. The clinical course of pneumonitis was characterised by an early onset (day 28) and a rapidly overwhelming course. Donor and recipient had pre-graft IgG Ab against toxoplasma without IgM. These Abs had completely disappeared from the serum of the patient at the time of pneumonitis. PCR amplification detected the B1 gene of Toxoplasma gondii in the patient's PBMC from day 28.

Animals↗

[Implantable insulin pumps: evaluation after more than 3 years experience].

Since the beginning of insulin therapy the improvement of treatment in IDDM is mainly for acute metabolic complications than for chronic degenerative complications. The DCCT could recently prove for the first time that the incidence of chronic complications (retinopathy, nephropathy and neuropathy) could be diminished by reaching glycemic control in more than 700 patients. One of the problems explaining the failure of classical treatment is due to the variability of absorption in the sub-cutaneous tissue. The patients treated by insulin pumps are all IDDM. The aim of this study is to evaluate safety and feasibility of implantable programmable pumps with intraperitoneal insulin infusion. We found three cases of irreversible catheter obstruction. Defects of external communicators and the slow-downs of insulin infusion in infusaid pumps were observed. No acceleration in insulin infusion was found. Acute metabolic complications were two severe hypoglycemic events, but no acito-cetosis. After more than two years for most of the patients we observed a global improvement in glycemic control, demonstrated by a better mean glycemia and lower HbA1c values. The standard deviation of the glycemia was lowered significantly, this value reflects daily fluctuability. The number of hypoglycemias was also lowered. Our study shows a more stable glycemic control than the one in the DCCT study. The safety and feasibility seem to be highly satisfying.

Adult↗