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Biomedical subjects

F Arnold

Publications and source records attributed to F Arnold.

At least 37 records · Page 2Linked to original sources
PubMed1998

Evidence for an heterogeneous glycosylation of the Clostridium tyrobutyricum ATCC 25755 flagellin.

Glycosylation analysis of the flagellin from the Gram-positive species Clostridium tyrobutyricum has been supplemented. Amino acid analysis of the glycopeptides obtained after pronase digestion of flagellin indicated that O-glycosylation which was previously demonstrated after nonreductive beta-elimination, probably occurred via the hydroxyl group of serine. Otherwise, beta-elimination partly deglycosylated flagellin. After this treatment carbohydrates were still linked to protein as shown by a digoxigenin-hydrazide labelling. Therefore, in addition to linkages via serine, alkaline resistant linkages exist on the flagellin and some glycans may be linked to the protein core via the amide nitrogen of asparagine or via the hydroxyl group of tyrosine. Furthermore, according to an immunological analysis, glycans attached to flagellin via alkaline sensitive linkages may be different from those attached via alkaline resistant linkages.

Amino Acids↗
PubMed1998

[Changes in indications in laparoscopic appendectomy?].

Acute appendicitis requires timely surgery. Still history and physical exam essentially lead us to the diagnosis. The definite histological-pathological finding of acute inflammation postoperatively confirms the diagnosis. Other findings especially chronic or chronic-recurrent inflammation should rise doubt. Therefore other criteria are needed to evaluate the quality of diagnosis for instance the nearly equal male to female relation of 1:1 in all appendectomies as well as in each decade. Today the principles of a strict indication for appendectomy becomes more loose because of the use of laparoscopy as we have shown in or own investigations. The valid standard have to be kept up, on the other hand we must reconsider the indication for surgery under the diagnosis "chronic or chronic-recurrent appendicitis".

Adolescent↗
PubMed1997

Outcome and cost of child abuse.

OBJECTIVE: To compare the cases of child abuse (CA) with other admissions in a pediatric intensive care unit (PICU) for differences in patient-specific health care costs, severity of illness (SI) and mortality, and describe their outcome. METHOD: A retrospective cohort study of all patients admitted to the PICU between January 1991 and August 1994. Discharge diagnosis, age, SI, mortality rate, length of stay, hospitalization charges ($Hosp), and mortality were retrieved. RESULTS: There were 937 admissions; 13 were secondary to CA. Cases of CA represented 1.4% of admissions and 17% of deaths. CA patients had the highest SI (61%), $Hosp ($30,684), daily charges ($5,294) and mortality rates (53%) than any other group. In our patients, SI is a factor that affects charges. Even when compared to a cohort group with SI, child abuse patients had higher daily hospitalization charges (p < .05). The medical bills for the acute care of a CA patient averaged $35,641 per case. Even with these expenditures, 70% died and 60% of the survivors had severe residual morbidity. CONCLUSION: These results confirm that interventional medical care in response to severe CA is very costly and the ultimate outcome is significantly worse than other diseases. Therefore, we believe it is imperative to allocate resources to prevention.

Analysis of Variance↗
PubMed1997

Postural vasoregulation and mediators of reperfusion injury in venous ulceration.

PURPOSE: To test the hypothesis that ischemia and reperfusion injury may contribute to the cause or nonhealing of venous ulcers, the effects of postural change on the microcirculation of ulcers and on levels of known mediators of reperfusion injury in their venous effluent were studied. METHODS: A standard protocol of stabilization (20 minutes), limb dependency (1 hour), and reelevation (2 hours) was used in 10 patients with venous leg ulcers as proven by clinical history, examination, ankle-brachial pressure index, and light reflective rheography. Superficial blood flow in and around ulcers was repeatedly examined with a new laser-Doppler scanning technique. Blood samples from the saphenous vein or a tributary adjacent to the ulcer before dependency and at 0, 10, 30, 60, and 120 minutes after reelevation were analyzed for tumor necrosis factor-alpha, interleukin (IL)-1RA, IL-1 beta, IL-6, platelet-activating factor, thromboxane B2, leukotriene B4, and P-selectin. RESULTS: Scans showed a consistent pattern of high ulcer blood flow, which decreased on dependency (p < 0.05) and then returned to baseline levels on reelevation and (in 7 of 10) eventually exceeded initial values. Mediator assays showed that levels of platelet-activating factor, IL-1RA, and IL-6 were significantly higher in resting ulcer venous effluent than in systemic venous samples; the reverse was true for P-selectin. There was no statistically significant change in effluent concentration of any mediator as a function of posture, ulcer size, or healing. CONCLUSIONS: Postural vasoregulation causes relative ischemia and reperfusion in venous leg ulcers. However, this is not associated with changes in release of mediators known to be related to reperfusion injury in internal organs.

Aged↗
PubMed1997

Pain in venous leg ulcers.

A prospective study was conducted to assess the prevalence, severity and diagnostic utility of pain in patients with venous leg ulcers. A semi-structured questionnaire was completed by 140 consecutive patients in two specialist centres caring for patients with leg ulcers. A high proportion (64%) of the 94 patients with ulcers of purely venous aetiology reported severe pain; 50% of these patients were taking either mild analgesia or none at all. In 10 of 72 cases, leg elevation made the pain worse. Venous ulcers are painful. Pain in three distinct locations was reported by patients-within ulcers, around ulcers and elsewhere in the leg. The presence of severe pain does not necessarily indicate arterial disease or infection. Pain is, in general, inadequately controlled in these patients.

Adult↗
PubMed1997

Mass screening programs for breast cancer in France--average values of assessment criteria.

Breast cancer is the most common cancer in women worldwide. Many studies have been performed worldwide to assess the effectiveness of screening in terms of reduced mortality due to breast cancer. Since the end of 1989, 10 breast cancer mass screening programs using mammography have been carried out in France under the sponsorship of the National Fund for Health Prevention, Education, and Information (FNPEIS) from the National Health Insurance of Salaried Workers (CNAMTS). These 10 campaigns, which are on a district scale, are organized according to variable methods and are assessed using a common procedure. Four groups of criteria are measured in this procedure, which investigates the impact, quality, effectiveness, and costs of screening programs. The average and extreme values of each criterion as calculated from the campaigns are presented in this paper. In order to enlighten the judgment on the French results, a comparison with the international standards in force and with the results of foreign screening programs is proposed.

Aged↗
PubMed1997

Monoclonal antibody detection of Clostridium microcolonies directly on membrane used for milk filtration.

The normal procedure for bacterial colony detection requires a nitrocellulose transfer step after membrane filtration and culture to prevent the development of a high background during the immunodetection. In this paper, we describe a modification of the basic protocol that omits the transfer step and reduces the risk of background. Previous observations indicated that interactions between milk components (principally cream) and membrane are responsible for the high non-specific staining observed. Experiments were performed to remove lipid components or to block the membrane binding sites before milk filtration. Samples of milks of different origin (collected at different times of the year) and different membranes were tested. The results obtained showed that removing lipids did not significantly improve the test but, on the contrary, led to an antigen diffusion. Incubation of the membrane in 0.1% (w/v) of Tween 20 in phosphate-buffered saline before milk filtration prevented non-specific binding, and allowed performance of the detection without any noticeable background.

Animals↗
PubMed1997

A mathematical model for the capillary endothelial cell-extracellular matrix interactions in wound-healing angiogenesis.

Angiogenesis, the process by which new blood capillaries grow into a tissue from surrounding parent vessels, is a key event in dermal wound healing, malignant-tumour growth, and other pathologic conditions. In wound healing, new capillaries deliver vital metabolites such as amino acids and oxygen to the cells in the wound which are involved in a complex sequence of repair processes. The key cellular constituents of these new capillaries are endothelial cells: their interactions with soluble biochemical and insoluble extracellular matrix (ECM) proteins have been well documented recently, although the biological mechanisms underlying wound-healing angiogenesis are incompletely understood. Considerable recent research, including some continuum mathematical models, have focused on the interactions between endothelial cells and soluble regulators (such as growth factors). In this work, a similar modelling framework is used to investigate the roles of the insoluble ECM substrate, of which collagen is the predominant macromolecular protein. Our model consists of a partial differential equation for the endothelial-cell density (as a function of position and time) coupled to an ordinary differential equation for the ECM density. The ECM is assumed to regulate cell movement (both random and directed) and proliferation, whereas the cells synthesize and degrade the ECM. Analysis and numerical solutions of these equations highlights the roles of these processes in wound-healing angiogenesis. A nonstandard approximation analysis yields insight into the travelling-wave structure of the system. The model is extended to two spatial dimensions (parallel and perpendicular to the plane of the skin), for which numerical simulations are presented. The model predicts that ECM-mediated random motility and cell proliferation are key processes which drive angiogenesis and that the details of the functional dependence of these processes on the ECM density, together with the rate of ECM remodelling, determine the qualitative nature of the angiogenic response. These predictions are experimentally testable, and they may lead towards a greater understanding of the biological mechanisms involved in wound-healing angiogenesis.

Animals↗
PubMed1997

[Mass screening programs for breast cancer in France. Comparative evaluation].

OBJECTIVE: The purpose of this work was to comparatively assess the results of mass screening programs for breast cancer implemented in six French departments in 1986, within the scope of the National Fund for Health Prevention, Education and Information of the National Health Insurance Office of Salaried Workers. MATERIAL AND METHODS: The data collected by the screening centres were analyzed by ten assessment teams that were independent from the program promotion staff, all using the same evaluation form. A complementary population study performed in eight French districts then, allowed assessing the frequency of self-referred screening (mammography performed out of program). RESULTS: The rate of participation in screening programs, in relation to the invited population, ranged from 21 to 48%, according to the district (36% in average). This low participation was probably related to the extent of self-referred screening. In fact, 19 to 40% of women, according to the district, had previously had a screening mammographic coverage: rate was around 68% in women aged 50 to 69 years. Positive findings with mammography ranged from 4.5 to 15.8% (10.1% in average), while intervention rates ranged from 0.7 to 1.6% and detection rates from 3.8 to 6.2%. The ratio between benign tumors and cancers ranged from 0.7 to 2.1 according to the district. In order to enlighten the judgement on French results, we propose a comparison with the international standards in force. CONCLUSION: The various experiences with breast cancer screening in France show that this screening is technically feasible on the basis of existing medical structures. However, some criteria are still below the expected values, especially if compared with international standards. This result is probably accounted for by the high rate self-referred screening before age 40 in France. In these conditions, the question is whether extending breast cancer screening programs in France is an appropriate course of action.

Breast Neoplasms↗
PubMed1996

Fluorescence signaling of ligand binding and assembly in metal-chelating lipid membranes.

BACKGROUND: Chemical information is sometimes transmitted across cell membranes by ligand-induced assembly of receptors. We have previously designed a series of lipids with metal-chelating headgroups that can serve as general receptors for proteins containing accessible histidines. Such lipids can also be derivatized with pyrene, a fluorescent probe that has a different emission maximum when it is aggregated (excimer fluorescence) from that seen for the monomer. We set out to examine whether lipids of this kind would produce a signal in response to ligand binding. RESULTS: A model ligand, poly-L-histidine (poly(His)), bound specifically to pyrene-labeled Cu(II)-iminodiacetate lipid (Cu-PSIDA) within a membrane matrix. Binding of poly(His) induces the redistribution of Cu-PSIDA, so that it forms pyrene-rich domains that are detectable by the increased ratio of excimer to monomer fluorescence. Using rhodamine-labeled poly(His), we have shown that the receptor lipid domains correspond to poly(His)-rich domains below the lipid interface. CONCLUSIONS: The Cu-PSIDA receptor signals binding of the macromolecular ligand through its excimer fluorescence and allows the resulting domains formed by ligand assembly to be imaged. Fluorescent Cu-PSIDA can thus serve as an optical reporter of ligand-induced lipid reorganization.

Chelating Agents↗
PubMed1995

Perfusion imaging of skin island flap blood flow by a scanning laser-Doppler technique.

Conventional laser-Doppler perfusion measurements can only obtain information from a single site. Since superficial blood flow is heterogeneous, this is a serious limitation, particularly in studies of methods to improve skin flap survival. A scanning laser-Doppler instrument has been developed which provides both an image and quantitative information about perfusion of the superficial tissue. We have evaluated this instrument in a circumflex iliac artery island flap model in the pig. The validity of the model was demonstrated by fluorescein dye injection and histology. Elevation of flaps was found to increase proximal flap blood flow but to decrease it in the distal portion. In flaps subjected to arterial ischaemia (9 h) and reperfusion we found an early increase in proximal flow, which gradually extended distally over the first 40 to 60 min. 16 h later, flow had declined, compatible with reperfusion damage to the vasculature. We suggest that perfusion imaging may be a valuable technique for investigating the mechanisms and extent of reperfusion injury.

Animals↗
PubMed1994

[Experience in mass screening of breast cancer with mammography in France].

In the framework of the National Fund for Prevention, Health Education and Information, the setting-up in France, on an experimental basis, of mass breast cancer screening programs by mammography in ten departments leads to suggest a common protocol for the evaluation of these programs, before an eventual generalization to the whole country. These programs are based on common principles: local screening based on existing medical facilities, single view mammography with double reading. However, the screening organisation is different in each department according to the target population, the screening interval, the mode of invitation, the methods for arranging double reading, etc. The purpose of this article is to report on the work of the evaluation group of the ten programs, and to propose a methodology for comparing the screening experiences in order to measure the role of the organisation methods. It gives definitions and modes of calculations for the evaluation criteria in four fields: impact, quality, efficacy and cost (with details about the feasibility of data collection) and proposes a reflection on analysis techniques in order to develop an optimum mass screening strategy.

Aged↗
PubMed1993

A critique of conceptual and treatment approaches to borderline psychopathology in light of findings about childhood abuse.

A series of recent research findings has begung to supply strong evidence of a highly significant correlation between borderline psychopathology and experiences of repeated childhood trauma including sexual abuse (especially incest), physical abuse, and the witnessing of severe domestic violence (Bryer et al. 1987; Herman et al. 1989; Western et al. 1990; Zanarini et al. 1989). The replication of these results with different research samples is in contrast to the inconsistent findings associated with earlier etiological theories, in which the roots of borderline pathology were variously linked to schizophrenic or affective illnesses (Akiskal 1981; Akiskal et al. 1985; Klein 1977; Perry 1985), to derailments in the separation-individuation process (Kernberg 1975, 1976; Mahler and Kaplan 1977; Masterson and Rinsley 1975), to actual early losses and separations (Bradley 1979; Paris et al. 1988; Soloff and Millward 1983a, 1983b), to severe empathic failures during the first years of life (Adler and Buie 1979), or to more general family-based pathologies (Frank and Hoffman 1980; Frank and Paris 1981; Grinker et al. 1968; Gunderson and Englund 1981; Gunderson et al. 1980; Links 1990; Walsh 1977; Zinner and Shapiro 1975). Not only do current findings regularly identify 50% to 80% of subjects as victims of childhood abuse and trauma, but also several studies show that factors such as age of onset, severity, and type of abuse reliably discriminate between borderline and other diagnostic groups (Herman et al. 1989; Zanarini et al. 1989).

Adolescent↗