Limitations in the use of rifampicin-gelatin grafts against virulent organisms

AbstractObjective: Efficacy and duration of antibacterial activity of rifampicin-gelatin grafts against virulent organisms were evaluated in an animal model. Materials and Methods: Rifampicin-gelatin grafts were prepared with impregnation of Gelseal (Vascutek Ltd, Scotland) graft in 1 mg/mL rifampicin solution. Rifampicin-gelatin grafts (6 cm long; n = 24) and plain Gelseal grafts as controls (n = 4) were implanted into the canine abdominal aorta with inoculation of Staphylococcus epidermidis, Escherichia coli, or methicillin-resistant Staphylococcus aureus (MRSA), and the rifampicin-gelatin grafts were retrieved after 1 to 4 weeks. Disks cut from the retrieved rifampicin-gelatin grafts were placed on agar plates streaked with one of the organisms, and the graft antibacterial activity was assessed with the width of the inhibition zone. Results: In in vitro tests, initial inhibition zones (inhibition zone of 24 hours after incubation) of rifampicin-gelatin grafts against S epidermidis, MRSA, and E coli were 40.0 ± 0.3 mm, 36.0 ± 0.2 mm, and 11.8 ± 0.1 mm, respectively. In the implantation, S epidermidis -inoculated rifampicin-gelatin grafts had no findings of graft infection, and no colony growth was recognized on the plates streaked with the perigraft fluids. Initial inhibition zones of S epidermidis -inoculated rifampicin-gelatin grafts retrieved at 1 or 2 weeks were 20.1 ± 1.1 mm and 7.6 ± 1.0 mm, respectively. In E coli -inoculated and MRSA-inoculated rifampicin-gelatin grafts, all of the eight animals had perigraft abscess, and blood culture test results probed septicemia in five animals with patent grafts at death. Inhibition zones against E coli or MRSA were not formed on the plates streaked with the same organism, whereas initial inhibition zones of E coli -inoculated and MRSA-inoculated rifampicin-gelatin grafts on S epidermidis -streaked plates were 8.0 ± 0.2 mm and 18.5 ± 0.5 mm, respectively. In the MRSA group, however, recolonization of high minimal inhibitary concentration strains developed within the inhibition zones as early as 24 hours. Histologically, neither organisms nor inflammatory cells were found in S epidermidis -inoculated rifampicin-gelatin grafts and tissue ingrowth was recognized at 2 to 4 weeks, whereas E coli -inoculated and MRSA-inoculated rifampicin-gelatin grafts had aggressive neutrophil infiltration into the graft interstices, revealing establishment of uncontrollable graft infection. Conclusion: These results suggested that rifampicin-gelatin grafts are clearly valid for S epidermidis infection, whereas no efficacy was recognized against either MRSA or E coli graft infection because of early development of high minimal inhibitary concentration MRSA strains or poor susceptibility. (J Vasc Surg 2002;35:779-85.

Real-time observation of X-ray-induced intramolecular and interatomic electronic decay in CH2I2

The increasing availability of X-ray free-electron lasers (XFELs) has catalyzed the development of single-object structural determination and of structural dynamics tracking in realtime. Disentangling the molecular-level reactions triggered by the interaction with an XFEL pulse is a fundamental step towards developing such applications. Here we report real-time observations of XFEL-induced electronic decay via short-lived transient electronic states in the diiodomethane molecule, using a femtosecond near-infrared probe laser. We determine the lifetimes of the transient states populated during the XFEL-induced Auger cascades and find that multiply charged iodine ions are issued from short-lived (similar to 20 fs) transient states, whereas the singly charged ones originate from significantly longer-lived states (similar to 100 fs). We identify the mechanisms behind these different time scales: contrary to the short-lived transient states which relax by molecular Auger decay, the long-lived ones decay by an interatomic Coulombic decay between two iodine atoms, during the molecular fragmentation

Pericentric H3K9me3 Formation by HP1 Interaction-defective Histone Methyltransferase Suv39h1

Pericentric regions form epigenetically organized, silent heterochromatin structures that accumulate histone H3 lysine 9 tri-methylation (H3K9me3) and heterochromatin protein 1 (HP1), a methylated H3K9-binding protein. At pericentric regions, Suv39h is the major enzyme that generates H3K9me3. Suv39h also interacts directly with HP1. However, the importance of HP1 interaction for Suv39h-mediated H3K9me3 formation at the pericentromere is not well characterized. To address this question, we introduced HP1 binding-defective, N-terminally truncated mouse Suv39h1 (ΔN) into Suv39h-deficient cells. Pericentric H3K9me3-positive cells were not detected by endogenous-level expression of ΔN. Notably, ΔN could induce pericentric accumulation of H3K9me3 as wild type Suv39h1 did if it was overexpressed. These findings demonstrate that the N-terminal region of Suv39h1, presumably via HP1–Suv39h1 interaction, is required for Suv39h1-mediated pericentric H3K9me3 formation, but can be overridden if Suv39h1 is overproduced, indicating that Suv39h1-mediated heterochromatin formation is controlled by multiple modules, including HP1

Novel homozygous CLN3

Abstract Background Biallelic CLN3 gene variants have been found in either juvenile‐onset neuronal ceroid lipofuscinosis (JNCL) or isolated retinal dystrophy. It has been reported that most JNCL patients carry a common 1.02‐kb deletion variant homozygously. Clinical characteristics of patients with biallelic CLN3 missense variants are not well elucidated. Methods We described a 26‐year‐old Japanese male patient with isolated retinal dystrophy. Whole‐exome sequencing (WES) and transmission electron microscopy (TEM) were performed. Results Whole‐exome sequencing identified a novel homozygous CLN3 missense variant [c.482C>T; p.(Ser161Leu)]. Ophthalmoscopy revealed retinal degeneration and macular atrophy, and later attenuated retinal vessels. Severely reduced responses were observed in both rod and cone electroretinograms. In TEM of the patient's lymphocytes, fingerprint profiles, which are specific findings in CLN3‐associated JNCL, were observed in 16/624 (2.56%) lymphocytes of the patient, who has never exhibited neurological signs during the 13‐year follow‐up period. Conclusion Our results indicated that this novel CLN3 missense variant is associated with teenage‐onset isolated retinal dystrophy. This is the first report of any patient with CLN3‐associated disorder in the Japanese population. Although fingerprint profiles have never been reported in CLN3‐associated isolated retinal dystrophy, these profiles were observed, albeit infrequently, suggesting that frequency of the fingerprint profiles might depend on variant types