PubMed Health⌕ Search

Biomedical subjects

Shigeru Ichioka

Publications and source records attributed to Shigeru Ichioka.

At least 19 recordsLinked to original sources
PubMed2006

Arterioles' contribution to oxygen supply to the skeletal muscles at rest.

We tested the hypothesis that oxygen is supplied to the resting skeletal muscle by arterioles rather than by capillaries. This hypothesis was evaluated in rats and rabbits by combining different approaches (1) determination of the intravascular oxygen tension (PO2) in arterioles of different diameters, (2) measurement of the perfused capillary number in response to changes in tissue PO2, and (3) estimation of the optimum capillary number to provide oxygen efficiently to the surrounding tissue. The intravascular PO2 values of arterioles along the vessels decreased downstream, suggesting that a significant amount of oxygen diffuses from the arterioles to the surrounding tissue. The perfused capillary number decreased as the tissue PO2 level was elevated, and this mutual relationship displayed a nonlinear correlation. The results suggest that a boundary PO2 level affecting the capillary recruitment exists for tissue PO2 of less than 40 mmHg with the capillary blood-flow stops above that PO2 level. At a high PO2 level, therefore, the oxygen is supplied from the arterioles. Furthermore, an estimation of optimum capillary number reveals that the capillary arrangement is constructed to achieve sufficient oxygen supply to the muscle during exercise, rather than at rest. These results suggest that oxygen is supplied from arterioles to the resting skeletal muscle, whereas the oxygen is supplied from the capillaries during exercise.

Animals↗
PubMed2006

Vascular wall energetics in arterioles during nitric oxide-dependent and -independent vasodilation.

The objective of this study was to evaluate whether the nitric oxide (NO) released from vascular endothelial cells would decrease vessel wall oxygen consumption by decreasing the energy expenditure of mechanical work by vascular smooth muscle. The oxygen consumption rate of arteriolar walls in rat cremaster muscle was determined in vivo during NO-dependent and -independent vasodilation on the basis of the intra- and perivascular oxygen tension (Po2) measured by phosphorescence quenching laser microscopy. NO-dependent vasodilation was induced by increased NO production due to increased blood flow, whereas NO-independent vasodilation was induced by topical administration of papaverine. The energy efficiency of vessel walls was evaluated by the variable ratio of circumferential wall stress (amount of mechanical work) to vessel wall oxygen consumption rate (energy cost) in the arteriole between normal and vasodilated conditions. NO-dependent and -independent dilation increased arteriolar diameters by 13 and 17%, respectively, relative to the values under normal condition. Vessel wall oxygen consumption decreased significantly during both NO-dependent and -independent vasodilation compared with that under normal condition. However, vessel wall oxygen consumption during NO-independent vasodilation was significantly lower than that during NO-dependent vasodilation. On the other hand, there was no significant difference between the energy efficiency of vessel walls during NO-dependent and -independent vasodilation, suggesting the decrease in vessel wall oxygen consumption produced by NO to be related to reduced mechanical work of vascular smooth muscle.

Animals↗
PubMed2006

Orthopaedic POSSUM scoring system: an assessment of the risk of debridement in patients with pressure sores.

We hypothesised that the implementation of a validated method of audit, the Physiological and Operative Severity Score for enUmeration of Mortality and morbidity (POSSUM), would be useful in the evaluation of the risks of debridement in bedridden patients with pressure ulcers. With the orthopaedic version of POSSUM (O-POSSUM), physiological data and an operative profile are scored to predict mortality for 30 days postoperatively. Fourteen cases were analysed retrospectively. The difference in predicted mortality was compared with those who died and those who survived. The mean (SD) predicted mortality among those who died was 47 (16)%, and among those who lived was 18 (14)%. Those who died were classified as a relatively high risk group, and the values differed significantly (p=0.01). O-POSSUM may be helpful in audit.

Aged↗
PubMed2005

Bone marrow-impregnated collagen matrix for wound healing: experimental evaluation in a microcirculatory model of angiogenesis, and clinical experience.

OBJECTIVES: This study aims to investigate the effect of collagen matrix impregnated with bone marrow on wound healing angiogenesis in an effective microcirculatory model and to describe our clinical experience. METHODS: We used a skinfold chamber of original design which visualises microcirculation following wound creation on the dorsal skin of the mouse to establish an in vivo experimental model to estimate angiogenesis. Animals were divided into two groups: a bone marrow group (n = 6) in which bone marrow-impregnated collagen matrix was applied to the wound; and a control group (n = 7), in which collagen immersed in saline was applied, and functional capillary density was quantified during the repair process. RESULTS: The increase rate in functional capillary density during wound healing significantly increased in the bone marrow group on days 3, 5 and 7 after creation of the wound but no significant difference was detected on day 10. A patient with a chronic leg ulcer that had not responded to conventional therapy for 1 year was treated with autogenous bone marrow-impregnated collagen matrix and successful wound closure was obtained. CONCLUSION: The present study suggested that collagen matrix impregnated with bone marrow significantly promoted the repair process, especially in the early stage. The features of the treatment, including the possible use of a patient's own cells, simple method, immediate application without any processing procedure and preservation of the inclusive potentiality of bone marrow suspension, offer significant advantages in terms of the anticipated routine clinical use.

Animals↗
PubMed2005

Nitric oxide modulates oxygen consumption by arteriolar walls in rat skeletal muscle.

To study the role of nitric oxide (NO) in regulating oxygen consumption by vessel walls, the oxygen consumption rate of arteriolar walls in rat cremaster muscle was measured in vivo during flow-induced vasodilation and after inhibiting NO synthesis. The oxygen consumption rate of arteriolar walls was calculated based on the intra- and perivascular PO2 values measured by phosphorescence quenching laser microscopy. The perivascular PO2 value of the arterioles during vasodilation was significantly higher than under control conditions, although the intravascular PO2 values under both conditions were approximately the same. Inhibition of NO synthesis, on the other hand, caused a significant increase in arterial blood pressure and a significant decrease in arteriolar diameter. Inhibition of NO synthesis also caused a significant decrease in both the intra- and perivascular PO2 values of the arterioles. Inhibition of NO synthesis increased the oxygen consumption rate of the vessel walls by 42%, whereas enhancement of flow-induced NO release decreased it by 34%. These results suggest that NO plays an important role not only as a regulator of peripheral vascular tone but also as a modulator of tissue oxygenation by reducing oxygen consumption by vessel walls. In addition, enhancement of NO release during exercise may facilitate efficient oxygen supply to the surrounding high metabolic tissue.

Animals↗
PubMed2005

Nonlinear regulation of capillary perfusion in relation to ambient pO(2) changes in skeletal muscle.

To study the process of O(2) transport to tissue, we investigated how capillary perfusion is controlled in response to changes in tissue O(2) levels in skeletal muscle. Capillary red blood cell (RBC) velocity and perfused capillary recruitment were measured in rabbit tenuissimus muscle at various ambient oxygen tensions (pO(2)) by intravital microscopy. Both RBC velocity and capillary recruitment significantly decreased as the pO(2) level of the suffusate was increased, and the relationship between capillary perfusion, calculated from the velocity and recruitment data, and the pO(2) level of the suffusate clearly yielded a nonlinear correlation that fitted a sigmoidal curve. Capillary perfusion dramatically decreases or increases above or below a suffusate pO(2) level of around 40 Torr, where the O(2) dissociation curve of hemoglobin changes slope. These findings support the hypothesis that microvasculature possesses an intrinsic, effective flow-control mechanism by sensing the metabolic demands of tissue, intimately related to the O(2) saturation of hemoglobin.

Animals↗
PubMed2005

Estimating oxygen consumption rates of arteriolar walls under physiological conditions in rat skeletal muscle.

To examine the effects of vascular tone reduction on O2 consumption of the vascular wall, we determined the O2 consumption rates of arteriolar walls under normal conditions and during vasodilation induced by topical application of papaverine. A phosphorescence quenching technique was used to quantify intra- and perivascular PO2 in rat cremaster arterioles with different branching orders. Then, the measured radial PO2 gradients and a theoretical model were used to estimate the O2 consumption rates of the arteriolar walls. The vascular O2 consumption rates of functional arterioles were >100 times greater than those observed in in vitro experiments. The vascular O2 consumption rate was highest in first-order (1A) arterioles, which are located upstream, and sequentially decreased downstream in 2A and 3A arterioles under normal conditions. During papaverine-induced vasodilation, on the other hand, the O2 consumption rates of the vascular walls decreased to similar levels, suggesting that the high O2 consumption rates of 1A arterioles under normal conditions depend in part on the workload of the vascular smooth muscle. These results strongly support the hypothesis that arteriolar walls consume a significant amount of O2 compared with the surrounding tissue. Furthermore, the reduction of vascular tone of arteriolar walls may facilitate an efficient supply of O2 to the surrounding tissue.

Animals↗
PubMed2004

Distal perforator-based fasciocutaneous V-Y flap for treatment of sacral pressure ulcers.

Although the gluteal V-Y advancement flap has been recognized as the most reliable method for management of sacral pressure ulcers, its limited mobility has been a challenging problem. The authors present a new modification of the V-Y advancement flap to overcome the problem. After débridement, a large triangle is designed to create a V-Yadvancement flap on the unilateral buttock and the medial half is elevated as a fasciocutaneous flap, preserving the distal perforators in the muscular attachment. Then an arc-shaped incision is made in the gluteus maximus muscle along with the lateral edge of the triangular flap. The split muscle is elevated at a depth above the deeper fascia until sufficient advancement of the flap is obtained. This full-thickness elevation of the gluteus maximus muscle from the distal (lateral) side avoids the impairment of perforators or their mother vessels and achieves great advancement. Thirty-one patients with sacral pressure defects larger than 8 cm in diameter were treated using this surgical procedure. Overall, 93.5 percent of the flaps (29 of 31) healed primarily. The largest defect that was closed with a unilateral flap was 16 cm in diameter. The present technique accomplishes remarkable excursion of the unilateral V-Y fasciocutaneous flap, with high flap reliability and preservation of the contralateral buttock as well as gluteus maximus muscle function.

Adult↗
PubMed2004

Triple coverage of ischial ulcers with adipofascial turnover and fasciocutaneous flaps.

Despite a wide variety of flap options, ischial ulcers remain the most difficult pressure ulcers to treat. This article describes the authors' successful surgical procedure for coverage of ischial ulcers using adipofascial turnover flaps combined with a local fasciocutaneous flap. After debridement, the adipofascial flaps are harvested both cephalad and caudal to the defect. The flaps are then turned over to cover the exposed bone in a manner so as to overlap the two flaps. A local fasciocutaneous flap (Limberg flap) is applied to the raw surface of the turnover flaps. Twenty-two patients with ischial ulcers were treated using this surgical procedure. Overall, 86.4 percent of the flaps (19 of 22) healed primarily. Triple coverage with the combination of double adipofascial turnover flaps and a local fasciocutaneous flap allows for an easily performed and minimally invasive procedure, preservation of future flap options, and a soft-tissue supply sufficient for covering the prominence and bony prominence and filling dead space. This technique provides successful soft-tissue reconstruction for minor to moderate-size ischial pressure ulcers.

Adult↗
PubMed2004

Bone marrow cell implantation improves flap viability after ischemia-reperfusion injury.

This study attempted to clarify the effects of therapeutic neovascularization by bone marrow cells for salvaging flaps after ischemia-reperfusion injury. Bone marrow mononuclear cell layer (endothelial progenitor cell-enriched fraction) was isolated from the mouse femur and tibia. Symmetrical double flaps were elevated in mice. Each flap topically received phosphate buffered saline (PBS) or bone marrow cells in PBS. Flaps were subjected to 6-hour ischemia and subsequent reperfusion. On the seventh postoperative day, the flap survival area was measured (n = 27). The mean survival area of bone marrow cells-transplanted flaps was 66.3 +/- 18.0%, whereas control flaps showed a survival area of 49.7 +/- 22.2%. The difference was highly significant (P = 0.000209). Histologic examination revealed the average vascular density of bone marrow cells-transplanted flaps had significantly increased. The present study proved bone marrow cells acted with significant efficacy in promoting the survival of ischemia-reperfusion-mediated damaged tissue.

Animals↗
PubMed2003

Skin temperature changes induced by strong static magnetic field exposure.

High intensity static magnetic fields, when applied to the whole body of the anesthetized rat, have previously been reported to decrease skin temperature. The hypothesis of the present study was that in diamagnetic water, molecules in the air play significant roles in the mechanism of skin temperature decrease. We used a horizontal cylindrical superconducting magnet. The magnet produced 8 T at its center. A thermistor probe was inserted in a subcutaneous pocket of the anesthetized rats to measure skin temperature. Animals (n=10) were placed in an open plastic holder in which the ambient air was free to move in any direction (group I). Animals (n=10) were placed in a closed holder in which the air circulation toward the direction of weak magnetic field was restricted (group II). Each holder was connected to a hydrometer to measure humidity around the animal in the holder. The data acquisition phase consisted of a 5 min baseline interval, followed by inserting the animal together with the holder into the center of the magnet bore for a 5 min exposure and a 5 min postexposure period outside the bore. In group I, skin temperature and humidity around the animal significantly decreased during exposure, followed by recovery after exposure. In group II, skin temperature and humidity did not decrease during the measurement. The skin temperature decrease was closely related to the decrease in humidity around the body of the animal in the holder, and the changes were completely blocked by restricting the air circulation in the direction of the bore entrance. Possible mechanisms responsible for the decrease in skin temperature may be associated with magnetically induced movement of water vapor at the skin surface, leading to skin temperature decrease.

Adaptation, Physiological↗
PubMed2003

Analytic review of 2372 free flap transfers for head and neck reconstruction following cancer resection.

Microvascular free tissue transfer has gained world-wide acceptance as a means of reconstructing post-oncologic surgical defects in the head and neck region. Since 1977, the authors have introduced this reconstructive procedure to head and neck reconstruction after cancer ablation, and a total of 2372 free flaps were transferred in 2301 patients during a period of over 23 years. The most frequently used flap was the rectus abdominis flap (784 flaps: 33.1 percent), followed by the jejunum (644 flaps: 27.2 percent) and the forearm flap (384 flaps: 16.2 percent). In the reported series, total and partial flap necrosis accounted for 4.2 percent and 2.5 percent of cases, respectively. There was a significant statistical difference ( p < 0.05) in complete flap survival rate between immediate and secondary reconstruction cases. The authors believe that the above-mentioned three flaps have been a major part of the armamentarium for head and neck reconstruction because of a lower rate of flap necrosis, compared to other flaps.

Cohort Studies↗
PubMed2003

Regenerative surgery for sacral pressure ulcers using collagen matrix substitute dermis (artificial dermis).

Collagen matrix substitute dermis, or artificial dermis, has recently been developed to induce angiogenesis and fibroplasia in deep, poorly vascularized tissue defects, and its use is desirable as a means of achieving effective treatment with less invasion. However, it is difficult to apply collagen matrix to pressure ulcers, because they are usually accompanied by infection with discharge of excessive amounts of exudate or pus and generally exposed to external forces that prevent graft fixation. To overcome these difficulties, the authors demonstrated a novel procedure to exclude unfavorable exudate and external forces. The procedure resulted in successful fixation of the artificial dermis and induction of regeneration in poorly vascularized defects in every case. The histologic findings provided supporting evidence that collagen matrix acts as a scaffold for reconstruction of nearly normal vascular structures coursing perpendicularly in the upper layer of normal dermis.

Humans↗
PubMed2002

In vivo model for visualizing flap microcirculation of ischemia-reperfusion.

Since ischemia-reperfusion injury continues to be a major problem in reconstructive microsurgery, improvement of experimental models is still desirable. We developed a model that allows direct visualization of flap microcirculation in mice by intravital microscopic techniques. A newly designed skinfold chamber was installed on the dorsum of mice, and microcirculation was inspected with an intravital microscope. An island flap, nourished by the deep circumflex iliac arteries, was elevated after implantation of the chamber, allowing visualization of the microcirculation in the island flap. The island flap was exposed to global ischemia by clamping the pedicles, and the clamps were then released to allow reperfusion. Various microcirculatory responses induced by ischemia-reperfusion were visualized. This model accurately simulated the clinical situation in reconstructive surgery and successfully realized chronic visualization of the flap microcirculation in vivo.

Animals↗
PubMed2002

Effect of hyperthermic preconditioning on the survival of ischemia-reperfused skin flaps: a new skin-flap model in the mouse.

To investigate whether hyperthermic preconditioning can actually protect skin flaps against ischemia/reperfusion injury, the authors first developed a new skin-flap model in 15 mice, a dorsal bipedicle island skin-flap model. Then, another 75 mice were separated into five groups. Mice in Groups 1 to 4 received the same hyperthermic preconditioning, but had different recovery times of 6 hr, 24 hr, 48 hr, and 72 hr, respectively. Mice in Group 5 served as control. Island skin flaps were elevated in all groups, and then were subjected to 8 hr of ischemia and subsequent reperfusion. Flap survival was statistically significantly higher than in controls in animals in Groups 1 and 3, with recovery times of 6 hr and 48 hr, respectively. Mice in Groups 2 and 4 had recovery times of 24 hr and 72 hr, respectively. Hyperthermic preconditioning could thus protect skin flaps against ischemia/reperfusion injury, and there were two optimal periods for such a protective effect.

Analysis of Variance↗
PubMed2002

Dorsal bipedicled island skin flap: a new flap model in mice.

Mice are popular animals for biomedical studies, but few skin flap models have been reported in them. To investigate the ischaemia/reperfusion phenomenon in skin flaps, we first investigated the vascular anatomy of murine dorsal skin and then designed a suitable murine dorsal skin flap model. In 120 mice, six distinct vascular patterns were identified, one being seen in 111 mice (93%). Based on this finding, in Part 2 of the study, 15 mice had flaps (4 x 4 cm) raised based on the two caudal vascular pedicles of the left and right deep circumflex iliac vessels as a bipedicled flap in which the mean (SD) survival was 96 (5)%. In a further 10 mice, flaps were raised based on a single pedicle, the left deep circumflex iliac vessel, as a monopedicled flap, in which the mean (SD) survival was 71 (12)%. The bipedicled flap model was then used to study ischaemia/reperfusion injury. Twenty flaps were subjected to eight hours of ischaemia and subsequent reperfusion, and their mean (SD) survival was 43 (26)%. Histological assessments were also carried out using neutrophil and leucocyte counts, and significant differences between groups were observed.

Analysis of Variance↗
PubMed2002

CATCH 22 Syndrome.

CATCH 22 syndrome is characterized by cardiac defects, abnormal facial features, thymic hypoplasia, cleft palate, and hypocalcemia. It results from a deletion within chromosome 22q11. This syndrome is not a simple disease. It includes DiGeorge syndrome, conotruncal anomaly face syndrome, and velocardiofacial syndrome. The authors report two cases of CATCH 22 syndrome.

Abnormalities, Multiple↗