Ultrastructure of the capillary pericytes and the expression of smooth muscle α‐actin and desmin in the snake infrared sensory organs

The infrared sensory membranes of pit organs of pit vipers have an extremely rich capillary vasculature that forms many vascular loops, each serving a small number of infrared nerve terminals. We clarified the ultrastructure of capillary pericytes in the pit membranes by scanning and transmission electron microscopy, and examined the immunoreactivity in their cytoplasm to two contractile proteins: smooth muscle α‐actin (SM α‐actin) and desmin. The capillary pericytes had two major cytoplasmic processes: thickened primary processes that radiate to embrace the endothelial tube and flattened secondary processes that are distributed widely on the endothelium. Coexpression of SM α‐actin and desmin was observed in the pericytes of entire capillary segments, and SM α‐actin was characterized by prominent filament bundles directed mainly at right angles to the capillary long axis. This expression pattern was different from that of capillary pericytes of the scales, where SM α‐actin was expressed diffusely in the cytoplasm. In a series of electron microscopic sections, we often observed the pericyte processes depressing the endothelial wall. We also observed a close relationship of the pericytes with inter‐endothelial cell junctions, and pericyte processes connected with the endothelial cells via gap junctions. From these findings, we surmised that capillary pericytes in the pit membrane have a close functional relationship with the endothelium, and through their contractile and relaxing activity regulate capillary bloodflow to stabilize production of infrared nerve impulses. Anat Rec 260:299–307, 2000. © 2000 Wiley‐Liss, Inc.     

Ultrastructure of the capillary pericytes and the expression of smooth muscle alpha-actin and desmin in the snake infrared sensory organs

The infrared sensory membranes of pit organs of pit vipers have an extremely rich capillary vasculature that forms many vascular loops, each serving a small number of infrared nerve terminals. We clarified the ultrastructure of capillary pericytes in the pit membranes by scanning and transmission electron microscopy, and examined the immunoreactivity in their cytoplasm to two contractile proteins: smooth muscle alpha-actin (SM alpha-actin) and desmin. The capillary pericytes had two major cytoplasmic processes: thickened primary processes that radiate to embrace the endothelial tube and flattened secondary processes that are distributed widely on the endothelium. Coexpression of SM alpha-actin and desmin was observed in the pericytes of entire capillary segments, and SM alpha-actin was characterized by prominent filament bundles directed mainly at right angles to the capillary long axis. This expression pattern was different from that of capillary pericytes of the scales, where SM alpha-actin was expressed diffusely in the cytoplasm. In a series of electron microscopic sections, we often observed the pericyte processes depressing the endothelial wall. We also observed a close relationship of the pericytes with inter-endothelial cell junctions, and pericyte processes connected with the endothelial cells via gap junctions. From these findings, we surmised that capillary pericytes in the pit membrane have a close functional relationship with the endothelium, and through their contractile and relaxing activity regulate capillary bloodflow to stabilize production of infrared nerve impulses.     

Application of X-ray grating interferometry for the imaging of joint structures

Conventional X-ray absorption contrast imaging does not depict soft tissues, such as cartilage, in sufficient detail. For visualization of the soft tissues, X-ray phase-contrast imaging is more sensitive than absorption-contrast imaging. The basic concept of the X-ray phase-contrast imaging used in this study is similar to that of differential interference contrast (Nomarski) microscopy. We applied Talbot–Lau X-ray interferometry to visualize the joint structures in the right hand and knee of a donated cadaver. This imaging system simultaneously produced three different types of images: an absorption image, a differential phase image, and a visibility image. The interface between the articular cartilage of the metacarpo-phalangeal joint and fluid or the bony cortex was clearly demonstrated on the differential phase image, whereas this interface was unclear on the absorption image. Within the knee joint, the surface of the articular cartilage was demonstrated both on the differential phase and visibility images; the medial collateral ligament and medial meniscus were also visualized successfully. These results are clinically significant for the diagnosis and therapeutic estimation of rheumatoid arthritis and related joint diseases. This feasibility study on the clinical application of this imaging tool was a collaborative effort of researchers in the fields of physics, radiology, and gross anatomy.     

Vascular endothelial growth factor receptor 1 (VEGFR1) tyrosine kinase signaling facilitates granulation tissue formation with recruitment of VEGFR1<Superscript>+</Superscript> cells from bone marrow

Vascular endothelial growth factor (VEGF)-A facilitates wound healing. VEGF-A binds to VEGF receptor 1 (VEGFR1) and VEGFR2 and induces wound healing through the receptor’s tyrosine kinase (TK) domain. During blood flow recovery and lung regeneration, expression of VEGFR1 is elevated. However, the precise mechanism of wound healing, especially granulation formation on VEGFR1, is not well understood. We hypothesized that VEGFR1-TK signaling induces wound healing by promoting granulation tissue formation. A surgical sponge implantation model was made by implanting a sponge disk into dorsal subcutaneous tissue of mice. Granulation formation was estimated from the weight of the sponge and the granulation area from the immunohistochemical analysis of collagen I. The expression of fibroblast markers was estimated from the expression of transforming growth factor-beta (TGF-β) and cellular fibroblast growth factor-2 (FGF-2) using real-time PCR (polymerase chain reaction) and from the immunohistochemical analysis of S100A4. VEGFR1 TK knockout (TK^?/?) mice exhibited suppressed granulation tissue formation compared to that in wild-type (WT) mice. Expression of FGF-2, TGF-β, and VEGF-A was significantly suppressed in VEGFR1 TK^?/? mice, and the accumulation of VEGFR1⁺ cells in granulation tissue was reduced in VEGFR1 TK^?/? mice compared to that in WT mice. The numbers of VEGFR1⁺ cells and S100A4⁺ cells derived from bone marrow (BM) were higher in WT mice transplanted with green fluorescent protein (GFP) transgenic WT BM than in VEGFR1 TK^?/? mice transplanted with GFP transgenic VEGFR1 TK^?/? BM. These results indicated that VEGFR1-TK signaling induced the accumulation of BM-derived VEGFR1⁺ cells expressing F4/80 and S100A4 and contributed to granulation formation around the surgically implanted sponge area in a mouse model.     

Amino acid residues required for Gtr1p‐Gtr2p complex formation and its interactions with the Ego1p‐Ego3p complex and TORC1 components in yeast

The yeast Ras‐like GTPases Gtr1p and Gtr2p form a heterodimer, are implicated in the regulation of TOR complex 1 (TORC1) and play pivotal roles in cell growth. Gtr1p and Gtr2p bind Ego1p and Ego3p, which are tethered to the endosomal and vacuolar membranes where TORC1 functions are regulated through a relay of amino acid signaling interactions. The mechanisms by which Gtr1p and Gtr2p activate TORC1 remain obscure. We probed the interactions of the Gtr1p‐Gtr2p complex with the Ego1p‐Ego3p complex and TORC1 subunits. Mutations in the region (179–220 a.a.) following the nucleotide‐binding region of Gtr1p and Gtr2p abrogated their mutual interaction and resulted in a loss in function, suggesting that complex formation between Gtr1p and Gtr2p was indispensable for TORC1 function. A modified yeast two‐hybrid assay showed that Gtr1p‐Gtr2p complex formation is important for its interaction with the Ego1p‐Ego3p complex. GTP‐bound Gtr1p interacted with the region containing the HEAT repeats of Kog1p and the C‐terminal region of Tco89p. The GTP‐bound Gtr2p suppressed a Kog1p mutation. Our findings indicate that the interactions of the Gtr1p‐Gtr2p complex with the Ego1p‐Ego3p complex and TORC1 components Kog1p and Tco89p play a role in TORC1 function.     

Alteration in stress distribution patterns through the elbow joint in professional and college baseball pitchers: Using computed tomography osteoabsorptiometry

Background

Long-term pitching activities change the stress distribution across the elbow joint surface in living subjects, however the influence of the different strength of stress on the stress distribution patterns remain unclear. The aims of this study were to evaluate the distribution of subchondral bone density across the elbow joint in different levels of pitchers, and to reveal the influence of the strength of stress on the elbow joint surface under long-term loading conditions of baseball pitching.

Extended operation for invasive thymoma with intracaval and intracardiac extension.

Two cases of invasive thymoma with intracaval and intracardiac extension into the right atrium are reported. Radical excisions and reconstructions of the superior vena cava (SVC) requiring extracorporeal circulation were performed. Invasive thymoma with this growth pattern is extremely rare, and patients with SVC obstruction should be evaluated for the resection of tumors and reconstruction of the SVC.     

Clinical implication of pulmonary excision for undiagnosed peripheral lung cancer

Surgical excision is an option to diagnose small-sized lung cancer, although this procedure has potential to disseminate tumor cells from the surgical margin. This retrospective study enrolled 252 patients with clinical stage IA non-small cell lung carcinoma who had undergone lobectomy during the period 1998-2004. Except for 25 patients with ground-glass attenuation (GGA) lesions on computed tomography, all underwent preoperative biopsy using flexible fiberoptic bronchoscopy (FFB). A total of 148 patients were diagnosed by FFB, and 86 were diagnosed by surgical excision. In the surgical excision cases, 67 tumors were negative for malignancy at the surgical margins and 19 were positive. Diagnosis by surgical excision was associated significantly more often with smaller tumor size (P<0.0001), a greater number of GGA lesions (P=0.0006) and a lower pathological stage (P=0.001) than those diagnosed by FFB. Furthermore, these patients showed better survival (P=0.03) and fewer local recurrences than patients diagnosed by FFB. In the groups that underwent excision, there was no significant difference in survival between those with positive and negative cytological margins. The survival of patients diagnosed by surgical excision was significantly better than that of those diagnosed by FFB in clinical stage IA disease. Surgical excision is an optimal method to diagnose small lung cancer because the malignant status of the margin does not appear to influence the outcome.     

Parameters affecting prognosis after hemodialysis withdrawal: experience from a single center

Clinical and Experimental Nephrology - Withdrawal from maintenance hemodialysis is unavoidable in some patients due to their poor general condition; however, their survival days vary depending on...     

Covering the below-knee amputation stump with the pedicled dorsalis pedis flap from the ipsilateral foot: a case report

It is important to preserve the length, appropriate durable skin, and sensation of the stump when performing below-knee amputation to achieve functional ambulation with a prosthesis. There are many reports of reconstruction procedures using microvascular surgery to preserve the optimum length of the amputation stump for prosthesis; however, free tissue reconstruction is necessary to accompany with the donor site morbidity. In this report, we describe our experience with a below-knee amputation and stump covering using the pedicled dorsalis pedis flap from the no longer usable foot in the case of a severe osteomyelitis of a lower extremity after highly contaminated Gustilo type IIIB fracture. We achieved a well-healed amputated stump with enough length for a prosthesis and for protective sensation. The pedicled dorsalis pedis flap is easily elevated without microvascular anastomosis and is one useful option for the reconstruction of the below-knee amputated stump in the specific case.