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Biomedical subjects

F Simon

Publications and source records attributed to F Simon.

At least 19 recordsLinked to original sources
PubMed2006

Photolabile carboxylic acid protected terpolymers for surface patterning. Part 2: Photocleavage and film patterning.

The surface properties of films made of p-methoxyphenacyl derivative terpolymers, associated with photocleavage by UV irradiation, and their optical patterning are investigated. The deprotection reaction has been monitored by UV and FTIR spectroscopy, contact angle measurements, and X-ray photoelectron spectroscopy, revealing the photoremoval of the protecting p-methoxyphenacyl group in high yields under mild conditions. Parallel and serial patterning of the films has been performed by selective irradiation through optical masks and by laser irradiation via fiber tips of a scanning near-field optical microscope, respectively. By irradiation of photolabile protected functional groups, free carboxylic groups become exposed to the surface with which fluorescent dyes and proteins can be associated specifically.

Carboxylic Acids↗
PubMed2006

Magnetic fullerenes inside single-wall carbon nanotubes.

C(59)N magnetic fullerenes were formed inside single-wall carbon nanotubes by vacuum annealing functionalized C(59)N molecules encapsulated inside the tubes. A hindered, anisotropic rotation of C(59)N was deduced from the temperature dependence of the electron spin resonance spectra near room temperature. Shortening of the spin-lattice relaxation time T(1) of C(59)N indicates a reversible charge transfer toward the host nanotubes above approximately 350 K. Bound C(59)N-C(60) heterodimers are formed at lower temperatures when C(60) is coencapsulated with the functionalized C(59)N. In the 10-300 K range, T(1) of the heterodimer shows a relaxation dominated by the conduction electrons on the nanotubes.

Journal Article↗
PubMed2006

Seroprevalence of canine heartworm disease (Dirofilaria immitis) on Tenerife Island: an epidemiological update.

Blood samples from 823 dogs were tested for circulating Dirofilaria immitis antigen during a 1-year period (May 2002 to May 2003) on Tenerife Island, Canary Islands, Spain. Seroprevalence of heartworm infection was 21%. Heartworm infection was similar in males and females and was more common in dogs aged >6 years. Distribution of infection in varying climatic zones was not statistically different.

Animals↗
PubMed2006

[Differential diagnosis of preneoplastic lesions of the pleura and of early mesothelioma: immunohistochemical and morphological findings].

The morphological diagnosis of small mesothelial lesions in pleural biopsies is gaining importance in view of more aggressive, multimodal therapeutic options and of medicolegal aspects if a malignant mesothelioma is diagnosed. We present a light microscopically and immunohistochemically based morphological classification for the planning of further clinical follow-up procedures. A reactive mesothelial hyperplasia heals without scars. Mesothelial inclusions in pleuritic scars are common in recurrent pleuritis and must not be confused with an epithelioid component of a desmoplastic mesothelioma. In case of atypical mesothelial proliferations, further diagnostic procedures have to be performed to obtain a clear diagnosis of malignancy. Mesothelioma in situ is the first morphological step in neoplastic mesothelial changes, also with regard to medicolegal aspects for the unambiguous diagnosis of a mesothelioma. Early infiltrative growth is characteristic of so called early mesothelioma. A useful immunohistochemical panel for the differential diagnosis consists of anti-cytokeratin, Ck 5/6, calretinin, EMA and MiB-1, whereas the immunohistochemical detection of telomerase is not helpful.

Biomarkers, Tumor↗
PubMed2006

XPS studies of chemically modified banana fibers.

Banana fibers obtained from the sheath of the banana plant (Musa Sapientum) whose major constituent is cellulose were modified using various chemical agents in order to improve their compatibility with the polymer matrix. The change in the surface composition of the raw and chemically modified fiber was investigated using various techniques such as solvatochromism, electrokinetic measurements, and XPS. Surface characterization by XPS showed the presence of numerous elements on the surface of the fiber. Investigation of the surface after alkali treatment on the other hand showed the removal of most of the elements. Silane treatment was found to introduce a considerable amount of silicon on the surface of the fiber. The [O]/[C] ratio was found to decrease in all cases except for the fluorinated and vinyl silane treated fibers. Detailed investigation of the deconvoluted C 1s spectra revealed the change in the percentage atomic concentration of the various elements on the fiber surface. The dissolution of the various surface components by alkali treatment, which was earlier revealed by SEM, was further confirmed by XPS. The XPS results were found to perfectly agree with the solvatochromic and electrokinetic measurements.

Acetic Anhydrides↗
PubMed2006

Hepatitis viruses in non-human primates.

BACKGROUND: Previous epidemiological studies of rural human populations in Gabon reveal a high prevalence of human hepatitis A, B, C and D viruses. In order to investigate the prevalence of the blood-born hepatitis viruses in apes and monkeys living in the same area, we performed an epidemiological survey of HBV, HCV and HDV in wild-born non-human primates. METHODS: We tested 441 wild-born non-human primates from Gabon and Congo and 132 imported monkeys for the presence of serological markers of HBV, HCV and HDV infections. RESULTS: None of Cercopithecidae monkeys were reactive against HBV/HDV and HCV. In contrast, 29.2% of wild-born great apes (154 chimpanzees and 14 gorillas) were positive for HBV serological markers. Nine chimpanzees were in the replicative phase of HBV infection. None of these HBV infected chimpanzees exhibited symptoms or significant changes in serum clinical chemistry related to HBV infection. CONCLUSIONS: The negativity to HCV-related viruses and the negativity of the Cercopithecidae species tested against HBV/HDV do not allow us to definitively rule out the presence of an animal counterpart of human hepatitis viruses in non-human primates.

Animals↗
PubMed2006

[Overview of endemic treponematoses].

Endemic treponematoses including yaws, bejel, pinta are distinguished from venereal syphilis on the basis of epidemiological characteristics and clinical manifestations. They cannot be differentiated by morphological and serological methods. A few minor genetic differences have been identified among the subspecies (Treponema pallidum sp. pallidum, pertenue, endemicum, carateum). Although penicillin therapy is effective, these infectious diseases have yet to be eliminated.

Diagnosis, Differential↗
PubMed2006

[Risk of noscomial infection in intertropical Africa--part 1: background].

Nosocomial infection is a risk in any health care setting. A review of recent medical literature shows that there is a paucity of information on nosocomial infection in intertropical Africa. Often misunderstood or denied, nosocomial infection is in reality an underestimated public health problem at most medical facilities even university hospital centers. However most hospitals are confronted with the same financial, structural and logistics difficulties, with limited training and awareness about hospital hygiene among caregivers, and with situations bringing together contagious infections with susceptible subjects. Assessment of the risks for patients and caregivers is a necessary prerequisite for implementing measures to control nosocomial infections in intertropical Africa.

Africa↗
PubMed2006

[Cutaneous tuberculosis overview].

Cutaneous tuberculosis is now uncommon in industrial countries despite the rising incidence of extrapulmonary tuberculosis in areas with high prevalence of HIV infection. Nevertheless it is still important to know the multiple clinical manifestations of cutaneous tuberculosis and to be aware of new laboratory diagnostic methods such as polymerization chain reaction gene amplification.

DNA, Bacterial↗
PubMed2005

NMR evidence for gapped spin excitations in metallic carbon nanotubes.

We report on the spin dynamics of 13C isotope enriched inner walls in double-wall carbon nanotubes using 13C nuclear magnetic resonance. Contrary to expectations, we find that our data set implies that the spin-lattice relaxation time (T1) has the same temperature (T) and magnetic field (H) dependence for most of the inner-wall nanotubes detected by NMR. In the high-temperature regime (T approximately > or = 150 K), we find that the T and H dependence of 1/T1T is consistent with a 1D metallic chain. For T approximately < or = 150 K we find a significant increase in 1/T1T with decreasing T, followed by a sharp drop below approximately = 20 K. The data clearly indicate the formation of a gap in the spin excitation spectrum, where the gap value 2delta approximately = 40 K (congruent to 3.7 meV) is H independent.

Journal Article↗
PubMed2005

Structural brain changes in tinnitus.

Tinnitus is a common but poorly understood disorder characterized by ringing or buzzing in the ear. Central mechanisms must play a crucial role in generating this auditory phantom sensation as it persists in most cases after severing the auditory nerve. One hypothesis states that tinnitus is caused by a reorganization of tonotopic maps in the auditory cortex, which leads to an overrepresentation of tinnitus frequencies. Moreover, the participation of the limbic system in generating tinnitus has been postulated. Here we aimed at identifying brain areas that display structural change in tinnitus. We compared tinnitus sufferers with healthy controls by using high-resolution magnetic resonance imaging and voxel-based morphometry. Within the auditory pathways, we found gray-matter increases only at the thalamic level. Outside the auditory system, gray-matter decrease was found in the subcallosal region including the nucleus accumbens. Our results suggest that reciprocal involvement of both sensory and emotional areas are essential in the generation of tinnitus.

Adult↗
PubMed2005

Isotope engineering of carbon nanotube systems.

The synthesis of a unique isotope engineered system, double-wall carbon nanotubes with natural carbon outer and highly 13C enriched inner walls, is reported from isotope enriched fullerenes encapsulated in single-wall carbon nanotubes (SWCNTs). The material allows the observation of the D line of the highly defect-free inner tubes that can be related to a curvature induced enhancement of the electron-phonon coupling. Ab initio calculations explain the inhomogeneous broadening of inner tube Raman modes due to the distribution of different isotopes. Nuclear magnetic resonance shows a significant contrast of the isotope enriched inner SWCNTs compared to other carbon phases and provides a macroscopic measure of the inner tube mass content. The high curvature of the small diameter inner tubes manifests in an increased distribution of the chemical shift tensor components.

Journal Article↗
PubMed2005

Interpretation of contact angle measurements on two different fluoropolymers for the determination of solid surface tension.

Contact angle measurements with a large number of liquids on the semi-fluorinated acryl polymer EGC-1700 films are reported. The surface tension was determined to be gammasv=13.84 mJ/m2 from contact angles of octamethylcyclotetrasiloxane (OMCTS) and decamethylcyclopentasiloxane (DMCPS). Inertness of these two liquids makes them ideal for determination of surface tension of low-energy fluoropolymers. On the other hand, contact angles of many other liquids deviated somewhat from a smooth contact angle pattern that represents the EGC-1700 surface tension. It is argued that noninertness of the molecules of these liquids gives rise to specific interactions with the polymer film, causing the deviations. Furthermore, contact angles of a series of n-alkanes (n-hexane to n-hexadecane) showed systematic deviations from this curve, similar to the trend observed for n-alkanes/Teflon AF 1600 systems studied earlier. Adsorption of vapor of short-chain liquids onto the polymer film caused their contact angles to fall above the gammasv=13.84 mJ/m2 curve, and a parallel alignment of molecules of the long-chain n-alkanes in the vicinity of the solid was the explanation for the deviation of their contact angles below it. It is found that vapor adsorption effect is more significant in the case of Teflon AF 1600, while the alignment of liquid molecules close to the surface is more pronounced for EGC-1700.

Journal Article↗
PubMed2005

Electron delocalization and dimerization in solid C59N doped C60 fullerene.

Electron spin resonance and ab initio electronic structure calculations show an intricate relation between molecular rotation and chemical bonding in the dilute solid solution. The unpaired electron of C59N is delocalized over several C60 molecules above 700 K, while at lower temperatures it remains localized within short range. The data suggest that below 350 K rigid C59N-C60 heterodimers are formed in thermodynamic equilibrium with dissociated rotating molecules. The structural fluctuations between heterodimers and dissociated molecules are accompanied by simultaneous electron spin transfer between C60 and C59N molecules. The calculation confirms that in the C59N-C60 heterodimer the spin density resides mostly on the C60 moiety, while it is almost entirely on C59N in the dissociated case.

Journal Article↗
PubMed2005

[Comparison of chromosomal defects in primary tumor and metastases by comparative genomic hybridization (CGH)].

Molecular methods can complement the classical methods in pathology like macroscopic, histological and immunohistochemical examinations.Comparative genomic hybridization is a cytogenetic method to screen for gains and losses of chromosomal material in tumor cells. This method allows defect studies of archival paraffin-embedded and formalin-fixed tumor material. CGH can detect gains and losses of chromosomal material that are at least 10 to 20 megabases in size. This genome-wide screening method allows to study the cytogenetic relationship between differently located tumors of a patient. To answer the question if these different tumors are metastases of the primary lung tumor or independent primary tumors CGH analysis is a supplementary method that introduces new prospectives.

Chromosome Aberrations↗
PubMed2005

Identification of hepatitis B virus genome in faecal sample from wild living chimpanzee (Pan troglodytes troglodytes) in Gabon.

Non-invasive faecal sampling in the equatorial forest in Gabon allowed the first identification of the hepatitis B virus (HBV-Ch(RC170)) genome in samples collected from wild chimpanzees (Pan troglodytes troglodytes). The HBV-Ch(RCl70)sequence clustered with 100% bootstrap support with previous viral sequences obtained from Pan troglodytes subspecies. This is the first evidence of HBV infection in wild apes and confirms that the HBV-like strains thus far characterized in captive apes are directly related to those circulating in the wild.

Animals↗