Long-Term Results of Cell-Free Biodegradable Scaffolds for In Situ Tissue-Engineering Vasculature: In a Canine Inferior Vena Cava Model

We have developed a new biodegradable scaffold that does not require any cell seeding to create an in-situ tissue-engineering vasculature (iTEV). Animal experiments were conducted to test its characteristics and long-term efficacy. An 8-mm tubular biodegradable scaffold, consisting of polyglycolide knitted fibers and an L-lactide and ε-caprolactone copolymer sponge with outer glycolide and ε-caprolactone copolymer monofilament reinforcement, was implanted into the inferior vena cava (IVC) of 13 canines. All the animals remained alive without any major complications until euthanasia. The utility of the iTEV was evaluated from 1 to 24 months postoperatively. The elastic modulus of the iTEV determined by an intravascular ultrasound imaging system was about 90% of the native IVC after 1 month. Angiography of the iTEV after 2 years showed a well-formed vasculature without marked stenosis or thrombosis with a mean pressure gradient of 0.51±0.19 mmHg. The length of the iTEV at 2 years had increased by 0.48±0.15 cm compared with the length of the original scaffold (2–3 cm). Histological examinations revealed a well-formed vessel-like vasculature without calcification. Biochemical analyses showed no significant differences in the hydroxyproline, elastin, and calcium contents compared with the native IVC. We concluded that the findings shown above provide direct evidence that the new scaffold can be useful for cell-free tissue-engineering of vasculature. The long-term results revealed that the iTEV was of good quality and had adapted its shape to the needs of the living body. Therefore, this scaffold would be applicable for pediatric cardiovascular surgery involving biocompatible materials

Primary brain T-cell lymphoma of the lymphoblastic type presenting as altered mental status

The authors present a case of a 56-year-old man with altered mental status. Magnetic resonance imaging (MRI) of the brain revealed non-enhancing abnormalities on T2 and FLAIR imaging in the brainstem, cerebellum, and cerebrum. Immunohistochemisty demonstrated precursor T-cell lymphoblastic lymphoma. After treatment with methotrexate, he improved clinically without focal sensorimotor deficits and with improving orientation. MRI showed almost complete resolution of brainstem and cerebral lesions. To the authors’ knowledge, there are only five previous reports of primary central nervous system T-cell lymphoblastic lymphoma. Since treatable, it deserves consideration in patients with altered mental status and imaging abnormalities that include diffuse, non-enhancing changes with increased signal on T2-weighted images

Activation of cGMP-Dependent Protein Kinase Stimulates Cardiac ATP-Sensitive Potassium Channels via a ROS/Calmodulin/CaMKII Signaling Cascade

) channels, an ion channel critical for stress adaptation in the heart; however, the underlying mechanism remains largely unknown. The present study was designed to address this issue. channels was confirmed in intact ventricular cardiomyocytes, which was ROS- and CaMKII-dependent. Kinetically, PKG appeared to stimulate these channels by destabilizing the longest closed state while stabilizing the long open state and facilitating opening transitions. channels and contribute to cardiac protection against ischemia-reperfusion injury

Evidence for involvement of A-kinase anchoring protein in activation of rat arterial KATP channels by protein kinase A

We have investigated the possible role of A-kinase anchoring proteins (AKAPs) in protein kinase A (PKA) signalling to ATP-sensitive K+ (KATP) channels of rat isolated mesenteric arterial smooth muscle cells using whole-cell patch clamp and peptides that inhibit PKA–AKAP binding.Intracellular Ht31 peptide (20 μm), which inhibits the PKA–AKAP interaction, blocked KATP current activation by either dibutyryl cAMP or calcitonin gene-related peptide. Ht31-proline (20 μm), which does not inhibit PKA binding to AKAP, did not block KATP current activation.Ht31 reduced KATP current activated by pinacidil and also prevented its inhibition by Rp-cAMPS, effects consistent with Ht31 blocking steady-state KATP channel activation by PKA. However, Ht31 did not prevent KATP current activation by the catalytic subunit of PKA.An antibody to the RII subunit of PKA showed localization of PKA near to the cell membrane. Our results provide evidence that both steady-state and receptor-driven activation of KATP channels by PKA involve the localization of PKA by an AKAP

Insulin-like growth factor-I inhibits rat arterial K-ATP channels through PI 3-kinase.

Since, in addition to its growth-promoting actions, insulin-like growth factor-I (IGF-I) has rapid vasoactive actions, we investigated the effects of IGF-I on whole-cell ATP-sensitive K+ (K-ATP) currents of rat mesenteric arterial smooth muscle cells. IGF-I (10 or 30 nM) reduced K-ATP currents activated by pinacidil or a membrane permeant cAMP analogue. Inhibition of phospholipase C, protein kinase C, protein kinase A, mitogen-activated protein kinase or mammalian target of rapamycin (mTOR) did not prevent the action of IGF-I. However, inhibition of K-ATP currents by IGF-I was abolished by the tyrosine kinase inhibitor genistein or the phosphoinositide 3-kinase inhibitors, LY 294002 and wortmannin. Intracellular application of either phosphatidylinositol 4,5-bisphosphate (PIP-2) or phosphatidylinositol 3,4,5-trisphosphate (PIP-3) increased the K-ATP current activated by pinacidil and abolished the inhibitory effect of IGF-I. Thus, we show regulation of arterial K-ATP channels by polyphosphoinositides and report for the first time that IGF-I inhibits these channels via a phosphoinositide 3-kinase-dependent pathway