Newly developed hybrid suture without lubricant: noninvasive in vivo assessment of biocompatibility with multiparametric MR imaging.

Magnetic resonance imaging (MRI) and magnetic resonance (MR) relaxometry were used to assess noninvasively the tissue response of a new uncoated hybrid braided suture made from a combination of ultra-high-molecular-weight polyethylene (UHMWPE) and polyester (polyethylene terephthalate) (PET) yarns in comparison to a silicone impregnated braided 100% polyester (PET) control suture (Ticron). Both biomaterials were monitored for a period of 30 days following implantation in both incised and nonincised paravertebral rabbit muscles. In all cases, MR images and relaxometry demonstrated that the hybrid suture elicited either a milder or a similar tissue and cellular response compared to the control suture. These findings were confirmed by conventional histological analysis of the surrounding tissues. They also demonstrated that the hybrid suture promoted faster healing in terms of collagen infiltration between the yarns and individual filaments. This milder inflammatory reaction and improved biocompatibility represent a real advantage in the healing performance of sutures for cardiac and vascular surgery, and support the need for continued research and development of hybrid structures. This study also demonstrated the ability of MRI techniques to noninvasively evaluate the biocompatibility of biomaterials. By extending the capacity of MR diagnostic tools from patients to experimental animals, it is now possible to validate the healing performance of foreign materials with statistical reliability and fewer animals.     

Biocompatibility studies of the Anaconda stent-graft and observations of nitinol corrosion resistance.

PURPOSE: To validate the deployment, in vivo performance, biostability, and healing capacity of the Anaconda self-expanding endoprosthesis in a canine aortic aneurysm model. METHODS: Aneurysms were surgically created in 12 dogs by sewing a woven polyester patch onto the anterior side of the thoracic or abdominal aorta. Anaconda prostheses were implanted transfemorally for prescheduled periods (1 or 3 months). Aneurysm exclusion and stent-graft patency were monitored angiographically. Healing was assessed with histological analysis and scanning electron microscopy (SEM). Textile analysis determined the physical and chemical stability of the woven polyester material, while the biostability of the nitinol wires was evaluated with SEM and spectroscopy. RESULTS: All prostheses were intact at explantation. After 1 month, endothelial-like cells were migrating in a discontinuous manner both proximally and distally over the internal collagenous pannus at the device-host boundary. After 3 months, endothelialization had reached the midsections of the devices, with a thicker collagenous internal capsule. Patches of endothelial-like cells were sharing the luminal surface with thrombotic deposits. However, the wall of the device at the level of the aneurysm was generally poorly healed, with multiple thrombi scattered irregularly over the luminal surface. The polyester fabric was intact except for some filaments that were ruptured adjacent to the sutures and some abrasion caused by the nitinol wires. No evidence of corrosion was found on the nitinol stents. CONCLUSIONS: This Anaconda stent-graft has demonstrated its ability to exclude arterial aneurysms. The device used in this study was an experimental prototype, and the manufacturer has incorporated new immobilization features into the model for clinical use. The constituent materials appear to be suitable in terms of biocompatibility, biofunctionality, and short-term durability.     

The depressing effect of tetracaine and ryanodine on the slow outward current correlated with that of contraction in voltage-clamped frog muscle fibres

The effects of tetracaine (10–50 M) and ryanodine (0.1–10 M) were tested on the slow outward K⁺ current (I _so) and the mechanical tension of isolated frog muscle fibres in a voltage-clamp device (double mannitol-gap) connected to a mechanoelectric transducer. In the concentration range tested, both drugs induced a simultaneous inhibition of tension and current. In all cases the effect on tension was twice that on current. The tetracaine-induced current and tension blocks were fully reversible and dose-dependent. In contrast the ryanodine effects on current and tension were not reversible and did not exhibit a dose dependence except for the delay before the onset of the response, which was shortened when the concentration was raised. Linear regression analysis of the time-dependent and dose-dependent effects of both drugs indicated a strong correlation between the decreases in tension and current. It is concluded that the slow outward current is partly under the control of the Ca²⁺ release from sarcoplasmic reticulum during contraction.     

Molecular evolution of human immunodeficiency virus type 1 subtype A in Senegal: 1988-1997

OBJECTIVE: Few studies have been able to track the genetic diversity of HIV-1 viruses in human populations over time. We analyzed the molecular evolution of subtype A over a 10-year period, in a cohort of female sex workers with a known time of infection. STUDY DESIGN/METHODS: We amplified and sequenced the C2-V3 region of the surface envelope glycoprotein from 73 HIV-1-infected women, infected between 1987-1997. RESULTS: Fifty-one patients were infected by subtype A viruses. The viruses demonstrated significant diversification (p < 0.001) with mean genetic distance increasing from 8.6% in 1989 to 15.9% in 1997. The slope of the fitted curve suggested a rate of diversification of 0.7% per year. The majority of subtype A viruses clustered with HIV-1 subtype A/G recombinant form (IbNG). CONCLUSION: The genetic diversity of HIV-1 subtype A infections doubled over the first 10 years of this high risk population's epidemic, suggesting that implementation of vaccines early in the epidemic may have a higher likelihood of success based on levels of genetic diversity. The A/G recombinant form (IbNG) has taken epidemic proportions in West Africa. This is of particular importance in understanding the epidemiology of HIV-1 subtypes in Africa and to further dissect the potential phenotypic and biological characteristics of these viruses.     

Arbovirus surveillance from 1990 to 1995 in the Barkedji area (Ferlo) of Senegal, a possible natural focus of Rift Valley fever virus

Surveillance for mosquito-borne viruses was conducted in Barkedji area from 1990 to 1995, following an outbreak of Rift Valley fever (RVF) virus in southern Mauritania. Mosquitoes, sand flies, and midges were collected from human bait and trapped by solid-state U.S. Army battery-powered CDC miniature light traps baited with dry ice or animals (sheep or chickens) at four ponds. Overall, 237,091 male and female mosquitoes representing 52 species in eight genera, 214,967 Phlebotomine sand flies, and 2,527 Culicoides were collected, identified, and tested for arboviruses in 9,490 pools (7,050 pools of female and 331 of male mosquitoes, 2,059 pools of sand flies and 50 pools of Culicoides). Viruses isolated included one Alphavirus, Babanki (BBK); six Flaviviruses, Bagaza (BAG), Ar D 65239, Wesselsbron (WSL), West Nile (WN), Koutango (KOU), Saboya (SAB); two Bunyavirus, Bunyamwera (BUN) and Ngari (NRI); two Phleboviruses, Rift Valley fever (RVF) and Gabek Forest (GF); one Orbivirus, Ar D 66707 (Sanar); one Rhabdovirus, Chandipura (CHP); and one unclassified virus, Ar D 95537. Based on repeated isolations, high field infection rates and abundance, Culex appeared to be the vectors of BAG, BBK, Ar D 65239 (BAG-like), and WN viruses, Ae. vexans and Ae. ochraceus of RVF virus, Mansonia of WN and BAG viruses, Mimomyia of WN and BAG viruses, and Phlebotomine of SAB, CHP, Ar D 95537, and GF viruses. Our data indicate that RVF virus circulated repeatedly in the Barkedji area.     

Specificities and functions of the recA and pps1 intein genes of Mycobacterium tuberculosis and application for diagnosis of tuberculosis

The worldwide recrudescence of tuberculosis and the widespread appearance of antibiotic resistance have strengthened the need for rapid and specific diagnostic tools. The prevailing microbiological identification of Mycobacterium tuberculosis, the causative agent of tuberculosis, which implies the use of in vitro cultures and acid-fast staining microscopy, is time-consuming. Detection of M. tuberculosis directly in clinical samples through PCR amplification of mycobacterium-specific genes, designed to shorten diagnostic delay, demonstrated reliability and high sensitivity. However, the quality of the diagnosis depends on the specificity of the target sequence for M. tuberculosis complex strains. In the present study, we demonstrated the specificity of recA and pps1 inteins for this complex and thus the feasibility of using intein-coding sequences as a new target for PCR diagnosis. Indeed, the recA and pps1 genes of 36 clinical isolates of M. tuberculosis and 10 field strains of M. bovis were found to be interrupted by an intein sequence at the RecA-a and Pps1-b sites, respectively, while a large number of nontuberculous mycobacterial species failed to demonstrate these insertions. Besides, the MtuPps1, which was cloned and expressed in Escherichia coli, was shown to possess an endonuclease activity. The intein cleaves the 40-bp sequence spanning the intein insertion site Pps1-b in the inteinless pps1 gene. In addition to the PCR amplification of recA and pps1 intein genes as a tool for diagnosis, the specific endonuclease activity could represent a new molecular approach to identify M. tuberculosis.     

Ultrasonographic aspects of urinary schistosomiasis in children of the Dogon plateau and the Niger office; impact of praziquantel treatment

Urinary bilharziasis is a parasitic infection responsible for vesical, urethral and renal lesions. The authors demonstrate the importance of ambulatory echography on a large scale and describe various echographic lesions. Vesical attacks occurred in 27% of the wall irregularity, 44% of the masses and polyps. Pyelic and urethral abnormalities occurred in 16.6% and 29.9% of cases respectively at the baseline in 1991. These prevalence rates decreased after seven years, in 1998. The authors discuss the utility of chemotherapy with praziquantel and the necessity of a periodical mass treatment in the areas with high bilharziasis endemicity in Mali.     

An association of HIV infection and noma in Niger

We report a case of noma having occurred in an adult female patient with HIV. The strain was characterized as HIV-1 group M subtype G. In order to explore the interactions between HIV/AIDS and this disease, we purpose systematic HIV screening for any case of noma, especially for adult patients.     

Molecular epidemiology of the RNA satellite of <Emphasis Type="Italic">Rice yellow mottle virus</Emphasis> in Africa

Summary. Satellite RNA was sought in 51 isolates of Rice yellow mottle virus (RYMV) representative of the geographical, molecular and pathogenic variability of the virus in Africa. Three-quarters of the isolates from cultivated rice and wild gramineaceous hosts supported a satellite RNA. The prevalence of RYMV isolates that were associated with a satellite differed among regions, being c. 100% in West and Central Africa and c. 36% in East Africa. The RYMV satellite showed a low diversity as only seven of the 220 sequenced positions were variable. One insertion also occurred after serial host passages of the satellite. Two forms of the satellite differed by six substitutions forming three base pairs in one branch of the predicted RNA secondary structure. There was no evidence of intermediates between these two forms, but double-infection occurred. Each form had a specific geographical distribution: one occurred in Central Africa, the other elsewhere in Africa. There was no relation between the occurrence or the forms of the satellite and the phylogeny of the helper virus. The satellite was not involved in symptom modulation or ability to break host-plant resistances to the disease.Received January 29, 2003; accepted April 12, 2003 Published online June 24, 2003