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Biomedical subjects

H Asato

Publications and source records attributed to H Asato.

At least 19 recordsLinked to original sources
PubMed2001

Motor unit properties of nerve-intact extensor digitorum longus muscle grafts in young and old rats.

Impaired reinnervation has been implicated as the cause of the threefold disparity in the recovery of maximum force (P0) of standard muscle grafts in old compared with young rats. The specific, null hypothesis of this study is that compared with age-matched control extensor digitorum longus (EDL) muscles, nerve-intact EDL muscle grafts in young and old rats show no evidence of an age-related impairment in reinnervation. Nerve-intact grafts were performed in 3-month-old and 23-month-old rats and were evaluated 60 days postoperatively. Compared with age-matched control EDL muscles, nerve-intact grafts in young and old rats showed no difference in muscle mass or motor unit numbers. The mean motor unit P0 for nerve-intact graft muscles in both age groups was significantly lower than that of age-matched control muscles. These data support our hypothesis that if axons are allowed to regenerate in an endoneurial environment, there is no evidence of an age-related impairment in muscle reinnervation.

Aging↗
PubMed2001

Mandibular reconstruction using microvascular free flaps: a statistical analysis of 178 cases.

For this article, 178 consecutive cases of mandibular reconstruction using microvascular free flaps and performed from 1979 to 1997 were studied. The purpose of this report is to compare flap success rates, complications, and aesthetic and functional results. The ages of the 131 men and 47 women ranged from 13 to 85 years, with an average of 55 years. Donor sites included the rib (11 cases), radius (one case), ilium (36 cases), scapula (51 cases), fibula (34 cases), and soft-tissue flaps with implant (45 cases). Complications included total flap necrosis, partial flap necrosis, major fistula formation, and minor fistula formation. The rate of total flap necrosis involving the ilium and fibula was significantly higher than that of all other materials combined (p < 0.05). The overall rate of implant plate removal, which resulted from the exposure or fracture of the plate, was 35.6 percent (16 of 45 cases). Each mandibular defect was classified by the extent of the bony defect and by the extent of the soft-tissue defect. The extent of the mandibular bony defect was classified according to the HCL method of Jewer et al. The extent of the soft-tissue defect was classified into four groups: none, skin, mucosal, and through-and-through. According to these classifications, functional and aesthetic assessments of deglutition and contour were performed on 115 subjects, and speech was evaluated in 110. To evaluate the postoperative results, points were assigned to each assessment of deglutition, speech, and mandibular contour. Statistical analysis between pairs of bone-defect groups revealed that there was no significant difference in each category. Regarding deglutition, statistical analysis between pairs of soft-tissue-defect groups revealed there were significant differences (p < 0.05) between the none and the mucosal groups and also between the none and the through-and-through groups. Regarding speech, there was a significant difference (p < 0.05) between the none and the through-and-through groups. Regarding contour, there were significant differences (p < 0.01) between the none and the through-and-through groups and between the mucosal and the through-and-through groups. The points given for each function, depending on the reconstruction material, revealed that there was no significant difference between pairs of material groups. From this prospective study, the authors have developed an algorithm for oromandibular reconstruction. When the bony defect is lateral, the ilium, fibula, or scapula should be chosen as the donor site, depending on the extent of the soft-tissue defect. When the bony defect is anterior, the fibula is always the best choice. When the soft-tissue defect is extensive or through-and-through with an anterior bony defect, the fibula should be used with other soft-tissue flaps.

Adolescent↗
PubMed2001

[Microvascular anastomoses in cervical esophageal reconstruction].

Ischemia or hemostasis in the gastric, jejunal, and colonic pedicle after esophagectomy is believed to contribute significantly to postoperative complications. With the advent of microvascular anastomoses, many surgeons have adopted vascular augmentation (supercharge) as a means of avoiding these difficulties. Microsurgical free tissue transfer represented by the free jejunum and forearm flap also plays an important role in esophageal reconstruction. In this paper, the authors introduce the technical points important for successful revascularization including the choice of recipient vessels, setting up of the reconstructive materials, and postoperative monitoring. In cases of gastric pull-up elevated via posterior mediastinum, the left gastroduodenal vessels are anastomosed to the cervical transverse or superior thyroidal vessels. In cases of duodenal or colonic pull-up elevated via the anterosternal route, the vascular pedicles are anastomosed to the internal mammary vessels which are dissected by resecting the costal cartilage. When the free jejunum flap is used, the cervical transverse or superior thyroidal vessels are most frequently used as recipients. Postoperative monitoring of free flaps is performed using Doppler ultrasound or through a small skin incision made above the transferred tissue. Although gastric or colonic pull-up is difficult to monitor, color Doppler sonography permits quantitative analysis of blood flow and may be a useful option.

Anastomosis, Surgical↗
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↗
PubMed2000

Endoscopic-assisted harvest of the temporoparietal fascial flap.

Elevation of the temporoparietal fascial flap by conventional T or Y incisions in the temporal region frequently leaves conspicuous scarring, hair thinning, or baldness. To avoid such undesirable effects, endoscopic-assisted harvest of the temporoparietal fascial flap was performed in 9 patients with microtia. Through two horizontal incisions in the temporal region, the temporoparietal fascia was dissected, and the flap was harvested using bipolar scissors and coagulating shears. Flaps were dissected and harvested successfully without any complications in 7 patients, although extra incisions were required to facilitate coagulation in 2 patients. The authors introduce this harvesting technique and describe some representative cases. Using endoscopic guidance, this is a versatile, safe procedure with minimal morbidity, and is applicable to other reconstructive procedures that require a temporoparietal fascial flap, including the free flap.

Adult↗
PubMed2000

Skeletal muscle reinnervation by reduced axonal numbers results in whole muscle force deficits.

Patients sustaining a peripheral nerve injury will frequently experience residual muscle weakness after muscle reinnervation, even if the nerve repair is performed under optimal circumstances to allow rapid muscle reinnervation. The mechanisms responsible for this contractile dysfunction remain unclear. It is hypothesized that after peripheral nerve injury and repair, a reduced number of axons are available for skeletal muscle reinnervation that results in whole muscle force and specific force deficits. A rat model of peroneal nerve injury and repair was designed so that the number of axons available for reinnervation could be systematically reduced. In adult rats, the peroneal nerve to the extensor digitorum longus muscle was either left intact (sham group, n = 8) or divided and repaired with either 50 percent (R50 group, n = 7) or 100 percent (R100 group, n = 8) of the axons in the proximal stump included in the repair. Four months after surgery, maximal tetanic isometric force was measured and specific force was calculated for each animal. Mean tetanic isometric force for extensor digitorum longus muscles from R50 rats (2765.7 +/- 767.6 mN) was significantly lower than sham (4082.8 +/- 196.5 mN) and R100 (3729.0 +/-370.2 mN) rats (p < 0.003). Mean specific force calculations revealed significant deficits in both the R100 (242.1 +/- 30 kN/m2) and R50 (190.6 +/- 51.8 kN/m2) rats compared with the sham animals (295.9 +/- 14 kN/m2) (p < 0.0005). These data support our hypothesis that after peripheral nerve injury and repair, reinnervation of skeletal muscle by a reduced number of axons results in a reduction in tetanic isometric force and specific force. The greater relative reduction in specific force compared with absolute force production after partial nerve repair may indicate that a population of residual denervated muscle fibers is responsible for this deficit.

Animals↗
PubMed2000

[A clinical investigation of infective endocarditis at a community hospital in Japan].

There have been few reports on the clinical features of infective endocarditis (IE) in Japan. We clinically investigates 45 episodes (36 cases) of definite IE that were experienced from January 1985 to March 1997 at a community hospital, Okinawa Chubu Hospital, Okinawa, Japan. Regarding age, prior dental procedure, causative organisms and sites of infection, analyses and comparison were performed on a total of 94 episodes, by adding another 49 episodes of IE that were experienced between 1977 and 1984 at our hospital. The mean age was 47 years and majority of patients in the recent 12 years were older than 50 years of age. Mortality of all 94 episodes was 20%, while that of recent 45 cases was 13%. Eight % of all episodes had history of recent dental treatment but significance of the finding remains unclear. Alpha streptococci were most common (33%) and Staphylococcus aureus was the second most common organism (17%). Eleven % of all episodes were culture-negative and there was a statistically significant difference in the histories of prior antibiotic therapy between culture-negative and culture-positive episodes. Regarding sites of infection, 27% of all episodes involved mitral valves, while 24% involved aortic valves. Prosthetic valves were involved in 12%. Ninety-eight % of the recent episodes had fever, 98% had cardiac murmurs and 27% had characteristic mucocutaneous lesions. Heart failure was the most common complication (27%) and half of the cases with prosthetic valve infection had heart failure. Cerebral embolism was most frequently seen among the major arterial embolic complications. Our results were similar to those which were previously reported from other countries. We should have a high index of suspicion for endocarditis whenever we see patients who present various clinical manifestations and fever of which origin remains unclear. Willingness to obtain blood culture before starting antibiotics is most important.

Adolescent↗
PubMed2000

Acute aortic valvular regurgitation secondary to avulsion of aortic valve commissure in a patient with pseudoxanthoma elasticum.

A 68-year-old woman developed acute pulmonary edema due to severe acute aortic valvular regurgitation. At the time of emergency surgery, it turned out to result from spontaneous avulsion of the aortic valve commissure. Later, the patient was diagnosed to have pseudoxanthoma elasticum based on typical skin lesions. Connective tissue abnormalities associated with pseudoxanthoma elasticum might have contributed to the development of the avulsion of the aortic valve in this particular patient.

Acute Disease↗
PubMed1999

The effect of reinnervation on force production and power output in skeletal muscle.

Failure to fully restore contractile function after denervation and reinnervation of skeletal muscle engenders significant disability in patients suffering peripheral nerve injuries. This work tested the hypothesis that skeletal muscle denervation and reinnervation result in a deficit in normalized power (W/kg), which exceeds the deficit in specific force (N/cm2), and that the mechanisms responsible for these deficits are independent. Adult Lewis rats underwent either transection and epineurial repair of the left peroneal nerve (denervation-reinnervation, n = 13) or SHAM exposure of the peroneal nerve (SHAM, n = 13). After a 4-month recovery period, isometric force, peak power, and maximum sustained power output were measured in the left extensor digitorum longus (EDL) muscle from each animal. Isometric force measurements revealed a specific force deficit of 14.3% in the reinnervated muscles. Power measurements during isovelocity shortening contractions demonstrated a normalized peak power deficit of 25.8% in the reinnervated muscles, which is accounted for by decreases in both optimal velocity (10.5%) and average force during shortening (13.7%). Maximum sustained power was similar in both groups. These data support our working hypothesis that both whole muscle force production and power output can be impaired in reinnervated muscle and that the relative deficits in power output exceed the deficits in force production. The mechanisms responsible for the deficits in force production appear to be independent of those that result in changes in peak power output. The measurement of muscle power output may represent a clinically relevant variable for studies of the recovery of mechanical function after motor nerve injury and repair.

Animals↗
PubMed1999

Elevation of a constructed auricle using the anteriorly based mastoid fascial flap.

Two-stage methods for reconstruction of congenital microtia have been widely utilised. To obtain a desirable auriculocephalic angle and provide a nutrient support to the constructed auricle, elevation of reconstructed ears using a costal cartilage graft, the anteriorly based mastoid fascial flap transfer and a skin graft was performed as the second operation for nine microtia patients. In this procedure, the mastoid fascial flap was used instead of the temporoparietal fascial flap. Following the elevation of the reconstructed ear the anteriorly based mastoid fascial flap was harvested. A carved costal cartilage was grafted at the posterior wall of the concha and covered with the mastoid fascial flap, followed by a full-thickness skin graft from the inguinal region. The skin grafts took well and the appropriate auriculocephalic angle was preserved in all cases. This method was easy to perform and did not leave any scar in the temporal hair-bearing area.

Adult↗
PubMed1999

Rat walking tracks do not reflect maximal muscle force capacity.

The relationship between walking-track measurements and maximum force generation in reinnervated rat hindlimb muscles was assessed. A rat model was designed to result in a broad range of recoveries of both muscle force and walking-track measurements after unilateral sciatic nerve injury and reconstruction. Three months following sciatic nerve injury, maximal force in the extensor digitorum longus (EDL) muscle ranged from 1325 to 3666 mN, and maximal specific forces ranged from 137.5 to 359.4 kNm(-2). In the same animals, functional intermediate toe spread factor (FIS) ranged from -0.03 to -0.78. Neither the correlation coefficient between EDL muscle maximal force and FIS (r = 0.4) nor that between EDL maximal specific force and FIS (r = -0.2) were statistically significant. The lack of correlation between muscle maximal force values and walking-track measurements suggests that these neuromuscular tests are assessing different factors.

Analysis of Variance↗
PubMed1999

Evaluation of muscle graft using facial nerve on the affected side as a motor source in the treatment of facial paralysis.

To acquire symmetry of the cheek when smiling, we carried out 39 free vascularised grafts of the muscle, the motor nerve of which was sutured to a stump of the ipsilateral facial nerve, for 39 patients with facial paralysis. We used two methods: an as healthy and fresh as possible facial nerve stump (method 1A, n = 17), or an incompletely affected stump (method 1B, n = 22). The results are classified into grade 1 to 5 indicating increasing efficiency of muscle function. All patients who had method 1A and 14 patients who had method 1B were evaluated grade 4 or better. Both an incompletely affected facial nerve stump and the proximal stump of a facial nerve that had previously been resected have sufficient function to provide contraction in the grafted muscle.

Adult↗
PubMed1998

Immunohistochemical analysis of clinically transplanted muscles.

BACKGROUND: Although a number of studies have examined the morphology and function of experimentally transplanted muscles, immunohistochemical evaluation of clinically transplanted muscles has not been reported. The purpose of this study was to examine clinically transplanted muscles at long periods after transplantation with biochemical markers specific for satellite cell activation and muscle regeneration. MATERIALS AND METHODS: Nine biopsies of muscles transplanted to the paralyzed face were examined. In five cases, the gracilis muscles were transplanted about 1 year after cross face nerve grafting. The other four cases underwent one-stage latissimus dorsi (LD) muscle transplantation. Twelve to 162 months after transplantation, muscle biopsies were harvested in nine cases. In eight cases, secondary corrections of facial expression including debulking of the grafted muscle were required, while another muscle was transplanted in one case because of the failed first operation. As control, six specimens of normal LDs were examined as well. Monoclonal antibodies were employed to visualize myosin heavy chain (MHC) isoforms (slow, fast, and embryonic) and MyoD protein. RESULTS: Although one specimen exhibited only small, atrophic fibers indicating failed reinnervation, the remaining eight specimens showed regularly distributed fibers and type grouping indicating successful reinnervation. There was no statistically significant difference in fiber area and lesser diameter between normal LDs and transplanted LDs. However, even in these successfully reinnervated muscles, intermediate and small fibers expressing embryonic MHC and small cells expressing MyoD were observed, suggesting that satellite cells were activated for repair of the adjacent fibers. CONCLUSIONS: Muscle adaptation (presumably to denervation), which is a regenerative change accompanied by activation of satellite cells, was still seen even long periods after transplantation. It is concluded that, in microneurovascular human skeletal muscle transfers, there is a wide variation in the time required for reinnervation of individual muscle fibers, and it may be that human muscle fibers cannot be properly reinnervated after denervation has continued for a certain period such as 12 months.

Adult↗
PubMed1998

Use of the disposable stapler to insure proper fixation of a transferred muscle in treatment of facial paralysis.

The authors introduce the use of a disposable stapler to create a stable muscle end in transferring a free neurovascular muscle segment for the treatment of facial paralysis. This procedure allows the firm fixation of the fragile soft end of a muscle transferred to the nasolabial region of a paralyzed face, and avoids adhesion and tethering of the muscle end to the skin, which may result in inaccurate positioning of a newly-created nasolabial fold and an asymmetrical smile. Transection and hemostasis at both ends of the harvested muscle segment also can be achieved simultaneously. Although the disposable stapler incurs additional cost, it can greatly improve the result of a free neurovascular muscle transfer for the treatment of facial paralysis, as well as simplify harvesting of the muscle segment. No complications and problems have been encountered in stapling the muscle.

Disposable Equipment↗
PubMed1998

Comparative evaluation in pharyngo-oesophageal reconstruction: radial forearm flap compared with jejunal flap. A 10-year experience.

We reviewed 109 consecutive patients with cancer of the hypopharynx or cervical oesophagus who underwent free flap transfer for immediate reconstruction after total pharyngolaryngo-oesophagectomy. The free flaps used were either free jejunal (n = 70) or radial forearm flaps (n = 39). Significantly more fistulas (3/70 compared with 15/39, p < 0.0001) and strictures (6/64 compared with 13/33, p = 0.0008) developed in the radial forearm than the jejunal flap group. However, functional donor site morbidity was minimal and there were no cases of total flap necrosis in the forearm flap group. We consider that the free jejunal flap should be the first choice for total reconstruction of pharyngo-oesophageal defects. However, the forearm flap is suitable for elderly, high risk patients, because it is less invasive and has minimal donor site morbidity, which facilitates early recovery.

Adult↗