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Biomedical subjects

S Ichioka

Publications and source records attributed to S Ichioka.

At least 19 recordsLinked to original sources
PubMed2005

Sprouting from arteriovenous shunt vessels with increased blood flow.

The purpose of this study was to evaluate the effect of increased blood flow on angiogenesis at the large vessels. The arteriovenous (AV) shunt was made on the thigh of male Wistar rats (n = 27) to increase blood flow, wrapped with artificial skin dermis, which consisted of a silicon outer layer, and isolated from surrounding tissues. Blood flow increased from 2.40 +/- 0.77 to 35.8 +/- 8.7 ml min(-1) (14.9 times), and the shear stress index (relative value of shear stress) increased from 10.7 +/- 3.6 to 73.4 +/- 18.1 (6.85 times) 60 min after the shunt formation. Newly formed vessels were observed around the AV shunt loop. Scanning electron micrographs at the AV shunt vessel lumen showed modified endothelial cells at day 7 and a remarkable number of pores at day 14. The volume of newly formed vessels was increased 12 times from day 5 to day 14. The mechanical factor of shear stress was considered the major stimulator of angiogenesis. This is the first report of electron-microscopic observation of sprouts from a large vessel lumen. The new AV shunt model is useful for basic research on angiogenesis at the large vessels in vivo and, furthermore, could generate vascularised tissues with various cultured cells.

Animals↗
PubMed2005

Benefits of surgical reconstruction in pressure ulcers with a non-advancing edge and scar formation.

OBJECTIVE: To highlight the difficulty in treating pressure ulcers associated with scar formation and the benefits of surgical treatment in these cases by presenting a series of clinical cases. METHOD: Nine sacral ulcers surrounded by significant scar formation and 14 sacral ulcers without significant scars were treated using the same conservative management protocol. Healing status was quantitatively estimated using an assessment tool called DESIGN, which classifies pressure ulcer severity and allows healing to be monitored; a decreasing score indicates progressive improvement. RESULTS: Ulcers with scar formation showed little response to the treatment, while those without remarkable scars exhibited a significant decrease of the DESIGN scores. Surgical reconstruction was conducted in five ulcers surrounded by scar formation, and all showed complete healing within extremely short periods. CONCLUSION: Conservative treatment of pressure ulcers with a non-advancing edge surrounded by scar formation presents considerable difficulties. Surgical reconstruction offers many benefits for non-healing ulcers.

Adult↗
PubMed2005

Evaluating dressing materials for the prevention of shear force in the treatment of pressure ulcers.

OBJECTIVE: Shear force is believed to affect pressure ulceration. Therefore, dressing materials that reduce shear force may prevent ulceration and facilitate healing. METHOD: We measured the following three properties: the coefficient of friction between the outer layer of the dressings and the patient's clothes; the degree of adhesiveness between the inner layer of the dressing and the patient's skin; the transmissibility of shear force of the dressing. RESULTS: The coefficients of static friction were 1.01 for hydropolymer, 0.72 for hydrofoam and 0.48 for hydrocolloid. Adhesiveness was tested by rolling different sized ball bearings down a slope and over the adhesive lining under both wet and dry conditions. Under dry conditions, the heaviest ball bearing that stopped rolling for five seconds was 111.9g for both hydrofoam and hydrocolloid. Under wet condition, it was 11.9g for hydrofoam and under 1g for hydrocolloid. Tests showed the very low transmissibility (I N buffer) of shear force for hydrofoam, with significant differences between the dressings. Clinical observation has identified good results for hydrofoam when used under highly exuding conditions and for hydrocolloid when used with relatively slight or decreased exudate. CONCLUSION: Existing dressing materials are being developed and evaluated for wound healing. However, if innovations in the raw materials from which dressings are manufactured could lead to a reduction in shear force and the prevention of pressure ulcers, then dressing materials could be discussed from a viewpoint that is quite different from wound healing.

Bandages↗
PubMed2001

Clinical use of amrinone (a selective phosphodiesterase III inhibitor) in reconstructive surgery.

Amrinone is a selective phosphodiesterase III inhibitor that increases cyclic adenosine monophosphate by preventing its breakdown. It is effective in the treatment of congestive heart failure because of its ability to increase myocardial contractility and vascular smooth muscle relaxation. This study was designed to clarify the potential efficacy of amrinone in plastic surgery by clinically assessing its ability to enhance flap blood flow after reconstructive surgery and relieve intraoperative vasospasm. Its effects were compared with those of prostaglandin E1 and lidocaine, which are widely approved agents for improving the hemodynamics of flaps. In the first clinical study, the effects on flap blood flow after flap transfers were investigated. Twenty-six patients underwent reconstructive surgery with vascularized free or pedicled flaps. Blood flow was measured before and 60 minutes after intravenous infusion of lactated Ringer solution (control), amrinone (10 microg/kg/min), or prostaglandin E1 (10 ng/kg/min) using a laser Doppler flowmeter. In the second study, the effects on relief of vasospasm during operation were evaluated. The blood flow of 28 island flaps was measured by laser Doppler flowmetry immediately after flap elevation and 10 minutes after topical application of saline (control), amrinone (5 mg/ml), or lidocaine (10%) to the pedicle in an attempt to resolve the vasospasm. In both clinical studies, the effects of amrinone were statistically no less than those of prostaglandin E1 and lidocaine. The results show that amrinone positively influences the microcirculatory blood flow of transferred flaps and relieves intraoperative vasospasm in clinical cases. The present study suggests that amrinone could be useful for postoperative and intraoperative care in reconstructive surgery.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2001

Microvascular and interstitial PO(2) measurements in rat skeletal muscle by phosphorescence quenching.

To clarify the transport of O(2) across the microvessels in skeletal muscle, we designed an intravital laser microscope that utilizes a phosphorescence quenching technique to determine both the microvascular and tissue PO(2). After we injected the phosphorescent probe into systemic blood, phosphorescence excited by a N(2)-dye pulse laser was detected with a photomultiplier over a 10 microm in diameter area. In vitro and in vivo calibrations confirmed that the present method is accurate for PO(2) measurements in the range of 7-90 Torr (r = 0.958) and has a rapid response time. This method was then used to measure the PO(2) of microvessels with different diameters (40-130 microm) and of interstitial spaces in rat cremaster muscle. These measurements showed a significant drop in PO(2) in the arterioles after branching (from 74.6 to 46.6 Torr) and the presence of a large PO(2) gradient at the blood-tissue interface of arterioles (15-20 Torr). These findings suggest that capillaries are not the sole source of oxygen supply to surrounding tissue.

Animals↗
PubMed2000

High-intensity static magnetic fields modulate skin microcirculation and temperature in vivo.

We investigated the acute effect of static magnetic fields of up to 8 T on skin blood flow and body temperature in anesthetized rats. These variables were measured prior to, during, and following exposure to a magnetic field in a superconducting magnet with a horizontal bore. The dorsal skin was transversely incised for 1 cm to make a subcutaneous pocket. Probes of a laser Doppler flowmeter and a thermistor were inserted into the pocket and positioned at mid-dorsum to measure skin blood flow and temperature. Another thermistor probe was put into the rectum to monitor rectal temperature. After baseline measurement outside the magnet, the rat was inserted into the bore for 20 min so that mid-dorsum was exactly positioned at the center, where the magnetic field was nearly homogeneous. Post-exposure changes were then recorded for 20 min outside the bore. Sham-exposed animals were submitted to exactly the same conditions, except that the superconducting magnet was not energized. Skin blood flow and temperature decreased significantly during magnetic field exposure and recovered after removal of the animal from the magnet. The rectal temperature showed a tendency to decrease while the animal was in the magnet. The microcirculatory and thermal reactions in the present study were consistent and agreed with some of the predictions based on mathematical simulations and model experiments.

Animals↗
PubMed2000

Topical application of amrinone (a selective phosphodiesterase III inhibitor) for relief of vasospasm.

BACKGROUND: Amrinone, a selective phosphodiesterase III inhibitor, is an agent that possesses a combination of positive inotropic and vasodilating properties as a result of preventing the degradation of cAMP, and it has recently been licensed for the treatment of heart failure. The aim of this study was to investigate the potential therapeutic application of amrinone to resolve vasospasm, which is the major problem in reconstructive surgery. In this study its effect was compared with that of lidocaine, the most commonly used topical vasodilating agent clinically. MATERIALS AND METHODS: The probe of an ultrasonic transit-time volume flowmeter was applied to the femoral artery of rats to measure blood flow. After a baseline recording was obtained, 0.03 ml of epinephrine was applied topically to induce vasospasm. The vessels were then immersed in 1 ml of amrinone (5 mg/ml), 10% lidocaine hydrochloride, or normal physiological saline solution for 1 min in an attempt to resolve the spasm. In another group of animals, no solution was used following administration of epinephrine to allow observation of spontaneous resolution of the vasospasm over time. RESULTS: The results showed an essentially immediate spasm-resolving effect in both the amrinone group and the lidocaine group. The amrinone group showed a significantly greater degree of maximum increase in blood flow than the lidocaine group. The effect of lidocaine decreased with time, whereas amrinone had a more lasting effect. CONCLUSIONS: The findings suggest that amrinone could be used as an effective topical vasodilating agent to resolve vasospasm in reconstructive surgery.

Administration, Topical↗
PubMed2000

Microsurgical reconstruction for caustic injuries of the oral cavity and esophagus.

Ingestion of caustic material often produces profound and irreversible pathologic changes that require reconstructive surgery of the organs damaged. This report describes the authors' successful experience with microsurgical techniques that allowed adequate reconstruction in three patients with cicatricial contracture of the oral cavity and esophagus following ingestion of caustic substances. All patients had attempted suicide by ingesting liquid alkali. Patients #1 and #2 complained of limited mouth opening and impaired tongue movement due to oral scar contracture. Contracture release in the first patient resulted in a defect from the anterior border of the mandible to the retromolar region. The defect was resurfaced with a 6 x 12 cm free forearm flap. Release of the scar contracture in the second patient resulted in a long, narrow, tortuous defect that was difficult to cover, even with a forearm flap, and a jejunal segment was microsurgically transferred as a patch graft to reconstruct the defect. Patient #3 had dysphagia due to stricture of the cervical portion of the esophagus. The defect after resection of the cervical portion was reconstructed by free jejunal interposition. Appropriately selected free-flap transfer in each case provided a satisfactory restoration of function of the oropharyngeal and digestive passages.

Adult↗
PubMed1999

Dual-beam laser illuminator of fluorescence microscope for in vivo microcirculation studies.

A new fluorescence intravital microscope of long working distance (39 mm) has been developed for the observation of microcirculation in a wide visual field by designing a simple epi-illumination technique with dual laser beams. Cross-illumination, in which a pair of laser beams is symmetrically placed on either side of the objective such that they intersect at the focal plane of the objective, was employed to produce uniform distribution of the incident light in the object plane. In vitro experiments using a fluorescein isothiocyanate dextran (FITC-dextran; molecular weight = 70,000) solution of known concentration confirmed uniform tracer excitation in a wide visual field (approximately 30 mm2), and a linear correlation between fluorescence intensity and tracer concentration (r = 0.999), ranging between 5 mumol l-1 and 25 mumol l-1. In vivo observations in the microcirculation of a hamster cheek pouch indicated that the present technique had the advantage of high contrast compared with the image obtained by bright-field transillumination. This microscope illuminator may prove useful for the evaluation of vascular permeability under physiological and inflammatory conditions, with sufficient quantitative reliability to determine tracer concentrations in all parts of the microvascular network. Furthermore, a long working distance in this technique could have considerable advantages for the application to nail-fold capillaroscopy in humans.

Animals↗
PubMed1999

Free jejunal patch to reconstruct oral scar contracture following caustic ingestion.

Reconstruction of oral scar contracture is often a challenging problem due to the complex structures and functions of the oral cavity. This report describes the treatment of a patient who sustained extensive oral scar contracture following caustic liquid soda ingestion. Surgical release of the scar contracture formed an S-shaped, thin, long defect that was difficult to cover with a conventional flap or skin graft. A jejunal segment was transferred microsurgically as a patch to reconstruct the defect. It sustained a sufficient oral space to provide full opening of the mouth and good movement of the tongue. A free jejunal flap, used occasionally for reconstruction following oral cancer resection, has significant advantages for restoration of function after release of an oral scar contracture.

Burns, Chemical↗
PubMed1999

Prefabricated free jejunal transfer: a new reconstructive technique for high pharyngeal defects.

A new method that uses a prefabricated free jejunal transfer has been applied to three cancer patients with pharyngoesophageal defects with a high pharyngeal deficit extending up to the nasopharynx. In this method, the jejunum harvested in the usual manner is divided into two segments with a single vascular pedicle. Its distal segment is used to reconstruct the cervical esophagus, and its proximal segment is turned over to create a mucosal patch to cover the high pharyngeal defects. The two segments are then co-apted in a side-by-side anastomosis. The esophagus can be reconstructed in a naturally straight shape without a curved portion or blind loop formation, thus leading to good swallowing function. In our series, all grafts survived well and there was no complication directly related to jejunal transfer. All patients could tolerate a soft diet without difficulty. This method is easy to perform and applicable to any shape or size of very high pharyngeal defects that cannot be reconstructed properly by other methods. Although patients with an advanced hypopharyngeal cancer usually have a poor prognosis, this technique allows a better quality of life for a probable short life span.

Aged↗
PubMed1999

[Recent advance in head and neck reconstruction].

The clinical application of microvascular free-flap transfers in reconstructive surgery has expanded tremendously since their introduction. Difficult reconstruction in the head and neck region can now be accomplished in a one-stage procedure using these techniques. Free flaps such as rectus abdominis, forearm, and scapular flap have been used frequently in this region because of their many advantages. They have a long vascular pedicle of a large-caliber vessel with anatomic stability and have ample blood supply. It is easy to harvest, and donor site morbidity in negligible. However, further improvement and refinement of surgical procedures are required to obtain better functional results and increase patients' quality of life. In this article, we describe the most recent concepts and techniques in head and neck reconstruction.

Head↗
PubMed1998

Amrinone, a selective phosphodiesterase III inhibitor, improves microcirculation and flap survival: a comparative study with prostaglandin E1.

BACKGROUND: Amrinone, a selective phosphodiesterase (PDE) III inhibitor, is a newly developed agent that possesses a combination of positive inotropic and vasodilating properties as a result of preventing the degradation of cAMP and it has recently been licensed for treatment of heart failure alone. Amrinone is expected to be useful for the treatment not only of heart failure but also of peripheral circulatory disorders, including vascular disease, and for ischemic flaps, because it improves microcirculatory hemodynamics. To investigate potential therapeutic applications of amrinone, we evaluated its ability to improve microcirculatory hemodynamics and flap survival. MATERIALS AND METHODS: The rat skinfold chamber technique was employed to quantify microcirculation directly in vivo. The improved survival area of random flaps in rats treated with amrinone was examined to assess therapeutic efficacy of this drug. Its effects were compared with those of prostaglandin E1 (PGE1), which has been widely approved as an agent for improving hemodynamics. RESULTS: Microcirculatory blood flow and flap survival area were significantly increased in both amrinone- and PGE1-treated animals, compared to the saline-treated controls. The ameliorating effects of amrinone were comparable to those of PGE1. CONCLUSIONS: The results of this study suggest amrinone to be a potentially useful drug not only for treating heart failure but also for improving microcirculation in patients with vascular diseases and for postoperative care after reconstructive surgery.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1998

In vivo measurement of morphometric and hemodynamic changes in the microcirculation during angiogenesis under chronic alpha1-adrenergic blocker treatment.

The effect of chronic administration of the alpha 1 blocker prazosin on microvascular angiogenesis was studied in rabbit ear chamber to investigate the role of concomitant increase in flow-oriented wall shear stress in vascular remodeling during angiogenesis. Rabbits were treated with prazosin hydrochloride (50 mg/liter in water) orally after ear chambers were installed. The microcirculation in the chamber was observed and recorded from 4 to 23 postoperative day (POD) by an intravital videomicroscope. The total vascular area (TA) were quantified as a morphometric parameter. Changes in wall shear stress in venules (20-40 micron ID) were calculated from flow velocity, vessel diameter, and in vivo blood viscosity. TA was significantly increased in the prazosin-treated animals. The levels of shear stress, which was increased 1.43 times by prazosin on 9 POD, gradually decreased toward the control level on 13 POD and they almost coincided on 21 POD. These findings experimentally provided supporting evidence that shear stress is probably involved in the adaptive response as one of mechanical factors regulating vascular remodeling during angiogenesis.

Adrenergic alpha-Antagonists↗
PubMed1998

Biological effects of static magnetic fields on the microcirculatory blood flow in vivo: a preliminary report.

There have been few studies of the effect of static magnetic fields on microcirculatory haemodynamics in vivo. The rat skinfold transparent chamber technique was used, which provides an excellent means of observing and quantifying direct in vivo microvascular haemodynamic responses to static magnetic fields up to 8 T. An intravital videomicroscope was used to measure the changes in blood flow before and after exposure to a magnetic field for 20 min in a horizontal type superconducting magnet with a bore 100 mm in diameter and 700 mm long. After exposure, microcirculatory blood flow showed an initial increase for about 5 min followed by a gradual decrease and a return to the control value. It is hypothesised that these changes represent rebound hyperaemia following reduced blood flow during exposure.

Animals↗
PubMed1998

An experimental comparison of hydrocolloid and alginate dressings, and the effect of calcium ions on the behaviour of alginate gel.

Gel-forming dressings, which absorb the wound exudate to form a non-adherent gel, accelerate wound healing in a moist environment. The most commonly used of these dressings are calcium alginate and hydrocolloid membranes. This study was designed to evaluate the physical properties of these dressings, including fluid retaining ability, gel formation, and the dissolution process to clarify the mechanisms that promote healing. A simple immersion method was used for measurement. This technique was useful for the quantitative assessment of gel-forming dressings and may help to evaluate potential application of these dressings. A comparative analysis showed that alginate dressings remained gelled longer than hydrocolloid dressings. This result was consistent with previously reported clinical features of these dressings. The absence of calcium in wound fluid induced rapid resolution of alginate gel while the presence of a certain concentration of calcium prevented degradation of the gel for as long as one month.

Alginates↗
PubMed1997

Effects of shear stress on wound-healing angiogenesis in the rabbit ear chamber.

Recent studies indicate that wall shear stress plays a significant role in the physiological adaptation of the vascular system. This study focused on the effect of sustained wall shear stress on wound-healing angiogenesis by exploring the morphologic and hemodynamic changes in developing microvessels in vivo through the tissue repair process. Rabbits were treated with the alpha 1 blocker prazosin (50 mg/L in water) orally from Day 0 to Day 23 after implantation of ear chambers to increase peripheral blood flow. The microvasculature in the chamber was recorded from Day 7 to Day 23 by using an intravital videomicroscope. The relative area of the chamber covered by vascularized tissue (%), the rate of ingrowth (mm2/day), the total vascular area (mm2), and the wall shear stress level (dyne/cm2) in venules (diameter in 20-40 microns) were quantified using a computerized image analysis system. The relative area increased significantly in the prazosin-treated animals from Days 7 to 19. The chamber of the treated group was completely covered with vascularized tissue earlier than that of the control group. The final total vascular area was larger by 21% in the treated group. The time course of shear stress in the treated group showed an initial elevation (1.44 times increase vs the control) followed by a gradual decrease toward the control level. These findings suggest that wound-healing angiogenesis may be partly involved in the adaptive response of microvasculature to shear stress.

Adrenergic alpha-Antagonists↗