One-component Diels–Alder based polyurethanes: a unique way to self-heal

In the present work, we synthesized one-component self-healing polyurethanes based on thermo-reversible furan/maleimide Diels–Alder reactions.

Free radical-induced grafting from plasma polymers for the synthesis of thin barrier coatings

Enhanced barrier properties of Al substrate coated by plasma polymer film grafted with radical-induced polymer.

Derivatization of free radicals in an isopropanol plasma polymer film: the first step toward polymer grafting

Plasma-polymerized films (PPF) synthesized by plasma-enhanced chemical vapor deposition (PECVD) find increasing applications in biomedicine and differ in many ways from conventional polymers. One of the most specific properties of the PPF is the high reactivity of its free-radical-rich surface, arising from the deposition mechanism. Although generally considered as a disadvantage leading to the aging of the PPF, reactivity of the plasma-treated polymers and PPF surfaces can be beneficially employed, for example, for grafting of a specific chemical functionality or short polymer chains. The quantitative evaluation of the surface radical density of the PPF is thus considered as the necessary preparatory step toward any subsequent grafting reaction. In the present study, the surface radical density of an isopropanol-based PPF was quantitatively determined by a combination of NO chemical derivatization and X-ray photoelectron spectroscopy (XPS). Once the derivatization conditions were optimized, the radical density, derived from at % N determined by XPS, was evaluated as a function of the deposition power. It was found out that the surface density of free radicals presents a maximum for the deposition power of 200 W (~2.3 × 10(14) spin/cm(2)) and it stabilizes (~2.1 × 10(14) spin/cm(2)) with further power increase. XPS findings were supported by in situ FTIR measurements that provided additional information about the degree of plasma fragmentation denoting fragmentation saturation for a deposition power of 200 W. By fitting the N1s peak it was possible to identify primary, secondary and ternary radicals and to study their respective evolutions with different deposition conditions. Angle-resolved XPS analysis allowed the in-depth distribution of radicals to be addressed, revealing that on the top surface, primary, and secondary radicals are dominating, whereas more tertiary radicals are present in the subsurface region. Finally, some preliminary chemical grafting experiments have allowed the relevance of derivatization results to be cross-checked.

[Characteristics of hepatitis B viral strains in chronic carrier patients from North-East Algeria]

OBJECTIVE

The goal of the study was to determine the characteristics of chronic hepatitis B virus (HBV) infections in the north-east part of Algeria. Chronic HBV infection remains a global public health issue and Algeria is considered as an intermediate prevalence area. Improving our knowledge on the epidemiology of this infection is a prerequisite to adopt the best preventive and curative strategy.

MATERIAL AND METHODS

We have studied 75 chronic hepatitis B patients from north-east Algeria. The characteristics of HBV strains were determined by use of serological and molecular testing. Genes encoding part of the precore, the surface and the polymerase were sequenced and phylogenetically analyzed.

RESULTS

Median age of the patients was 35 years and 80% of them had normal transaminase level. Liver histological lesions were identified in 63% of the patients who benefited from a liver biopsy and 21% of them had cirrhosis. Median viral replication was 3.9 Log IU/ml and 87% of patients had a "precore" mutant serological profile without HBe Ag. Genotype D was predominant (93%) followed by genotype A (5%) and E for one patient. Algerian strains clustered independently from other genotype D reference sequences, suggesting a possible new D subtype. Within the "precore" region, only 16% of the strains did not show any mutation at positions 1762/1764 and 1896.

CONCLUSION

In this original set of patients from north Algeria, the virologic characteristics of HBV are comparable to what has been described in other Mediterranean countries. Our study raises several important aspects with regard to the prevention and treatment of chronic hepatitis B in Algeria.

Comparison of SPECT lung perfusion with transbronchial lung biopsy after lung transplantation

The objective of this study was to evaluate the potential role for single photon-emission computed tomography (SPECT) using technetium 99m-macroaggregated albumin for diagnosing rejection in lung transplant patients. SPECT results were compared with those obtained from transbronchial biopsy (TBB) in patients undergoing bronchoscopy during routine surveillance and in cases of clinical, radiographic, or physiologic suspicion of lung rejection. This prospective, nonrandomized study was conducted by the Marseille Lung Transplant Group, Marseille University Hospitals South. It included 26 lung transplant recipients (19 double-lung, four single-lung, and three heart-lung). For each patient, SPECT lung perfusion was performed before TBB as part of routine surveillance protocol and when clinically indicated. Routine surveillance included TBB at 1, 3, 6, 9, and 12 months and every 6 months thereafter. SPECT was always performed within the 24 h preceding TBB. Whenever the SPECT was abnormal, biopsies were obtained from an area corresponding to a region of hypoperfusion. Results of the study were based on 79 paired SPECT and TBB obtained from 26 patients. Concordance between SPECT and biopsy occurred in 71 instances (89.9%). Among 25 cases of normal SPECT, TBB was normal in 24 and revealed subclinical lung rejection in one. Among 54 cases of abnormal SPECT, TBB was also abnormal in 47 (87.0%), with lung rejection being the abnormality in 23 (46%). For pairs performed as part of the routine surveillance protocol (61 pairs), clinically silent lung rejection was diagnosed in 16 (26.2%). SPECT was abnormal in 15 of 16 instances and normal in only one; this patient had minimal rejection that resolved without treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pulmonary perfusion tomoscintigraphy in pulmonary embolism. Preliminary study]

Tomoscintigraphy, a method developed over 10 years ago, is little used nowadays for the evaluation of suspected pulmonary embolism. The authors report the results of a preliminary study of 10 patients hospitalised for this condition. Tomoscintigraphy was normal in 2 cases and abnormal in 8 cases. Seven of these 8 patients underwent pulmonary angiography which confirmed the diagnosis of pulmonary embolism in 6 cases. The small number of patients, however, did not allow measurement of the sensitivity and specificity. Tomoscintigraphy, repeated at the 8th day and at the first month, provides an assessment of therapeutic efficacy. Some improvement is observed in all cases from the first control but the amount varies from one subject to another. At one month, 3 of the 6 patients undergoing control tomoscintigraphy had hypoperfusion sequellae. The simplicity of pulmonary tomoscintigraphy makes it a useful investigation for emergency diagnosis and follow-up pulmonary embolism.