Biomedical subjects
Publications and source records attributed to K Harii.
The development of a new rabbit model for study of neovascularization of the jejunal graft is described. The relationship between stripping of the serosal membrane and the speed of the neovascularization process was analyzed. The results demonstrate that the visceral peritoneum acts like a physical barrier, retarding the formation of the new nutrient blood supply from recipient bed to the jejunal graft.
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Electrodes were implanted in the grafted muscles of rabbits to generate continuous stimulation for the purpose of preventing denervation atrophy. Denervation atrophy could be prevented, to some extent, in dissected muscles with vascular pedicles not occluded during the experiment. Denervation atrophy was found to be promoted, rather than prevented, in grafted muscles with occluded vascular pedicles. The crucial conditions are varying stimulation and the long duration of occlusion (90 min). Overly strong stimulation of muscle contraction appears to result in "fatigue" of grafted muscles in which blood circulation has been blocked for more than the 90 min used in the reported experiment. Further investigations are necessary of the conditions of stimulation and the point in time at which stimulation should commence after grafting.
In the past 27 years, 75 patients were found to have separate primary carcinomas of the head and neck and the esophagus. Head and neck tumor was discovered first in 41 patients, synchronously with esophageal tumors in 17 patients, and esophageal tumors were recognized first in 17 patients. Reconstruction by graft after resection of head and neck cancer was necessary in 18 patients and esophagectomy was performed in 62 patients. In eight patients, pharyngeal and esophageal reconstruction was necessary after resection of synchronous and metachronous pharyngeal and esophageal carcinoma. The combined procedure with free tissue transfer was useful for surgical treatment for synchronous or metachronous carcinomas of the head and neck and the esophagus.
Microsurgical reconstruction of the face completely destroyed after malignant skin tumor excisions in a xeroderma pigmentosum patient is reported. The patient's left cheek was reconstructed using a free latissimus dorsi flap and the nose using a free forearm flap with a base of iliac bone graft. There has been no recurrence of tumor at or surrounding the transferred flap site over two years postoperative follow-up.
To study the histopathologic changes of spinal cords exposed to long-duration complete ischemia, the authors developed an upper-half-body transplantation model of inbred rat. In this model, an infant Lewis rat is transplanted to the inguinal region of another adult Lewis rat using microsurgical vascular anastomosis. Even when 2-week-old donor rats were exposed to complete ischemia for 90 minutes, functions of the spinal cord were comparatively preserved. In histopathologic observations, degeneration proportional to complete ischemia duration was noted. In the 60-minute ischemia group of 2-week-old donor rats, however, no substantial differences from normal spinal cord were observed. Under conditions of equal ischemia duration, it appeared the younger animal had the greater ischemic tolerance.
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We report herein, a rare case of a patient who, having undergone resection of a thoracic esophageal cancer, underwent removal of a cervical esophageal cancer, for which a free jejunal graft with microvascular anastomoses was utilized. The tumor in the cervical esophagus had originated from a second primary squamous cell cancer, which had occurred synchronously but had unfortunately escaped detection before the first operation. Due to the high incidence of other multicentric neoplasma or metastatic skip lesions accompanying esophageal carcinoma, careful evaluation during preoperative examinations in order to avoid overlooking another lesion, especially in the cervical portion of the esophagus is imperative.
A case of simultaneous carcinomas of the lower thoracic esophagus and the oropharynx in a 62-year-old man is reported. Reconstruction was successfully performed using a one-stage operation consisting of pharyngolaryngoesophagectomy followed by a combination of gastric pull-up and microvascular jejunal transfer procedures. The postoperative course was uneventful except for regurgitation of food, which persisted for 1 month.
A new experimental model is presented, using isohistogenic Lewis rats and microsurgical techniques. Transplantation of the head and forelimbs of the infantile rat was done to the groin of an adult rat. The goal was to study the effects of ischemia on brain tissue. This model also proved useful for other experiments in studies of facial and cranial bone growth. The model presented proved efficient for the study goals, and long-term experiments were possible. The maximum ischemia time tolerated by brain tissue was found to be somewhere between 60 min and 120 min.
Hypopharynx and cervical-esophageal reconstruction after malignant-lesion removal has been a challenging problem for head and neck surgeons. The reconstructive technique has been developed over the years through several ingenious methods of replacement. As a result of recent refinements in microvascular anastomosis techniques, many studies concerning one-stage, immediate cervical-esophagus reconstruction have been reported. An experimental study on esophageal reconstruction has been developed using a free intestinal transplantation in two distinct strains of rats. One of the groups consisted of a heterogeneous population of Wistar rats and the other an inbred Lewis strain. In our study the Wistar group reacted as in allograft transplantations and developed an immunological rejection process. The Lewis strain reacted according to isogenic transplantations. The surviving rats were killed and microscopical studies of the reconstructed esophagus were performed. This study is a low-cost, practical experimental model to achieve a better knowledge of the behavior of the transplanted organs.
Our first clinical success in microneurovascular free muscle transplantation for treatment of long-standing facial paralysis was in 1973. The author introduces his recent technical refinements of this clinical procedure and the results obtained.
The osteogenic capacity of vascularised periosteum was investigated in rabbits using island rib periosteum nourished by intercostal vessels as an experimental model. Twenty-three adult white female rabbits were used. Excellent bone formation was observed after 2 postoperative weeks in each case. In the early stages of bone formation, extensive chondral ossification was observed. Newly formed bone became mature after 4 to 8 postoperative weeks, on histological examination.
Technetium-99m Methylene Diphosphonate (Tc-99m MDP) has often been used to assess revascularisation of bone, because positive uptake of Tc-99m MDP reflects patent anastomoses and viability of the grafted bone. However, the sequential evaluation of bone scintigraphy has seldom been reported, especially in clinical cases. We carried out sequential evaluation in 17 patients with revascularised bone grafts. In this series, intense or maximal uptake in the grafted bone was observed in the early days after surgery (1-2 weeks postoperatively), with considerable reduction after 4 weeks. Furthermore, it was found that there was no uptake of Tc-99m MDP when the anastomosed vessels were occluded, even after 6 weeks, and these three cases all developed fracture or sequestrum. We therefore believe that bone scintigraphy is reliable in the postoperative monitoring of revascularised bone for at least 4 or 6 weeks postoperatively.
The hind limbs of young rats were transferred to adult rats to clarify the morphologic and growth changes of a young epiphyseal plate in an adult hormonal environment. The transplanted femur and tibia achieved about 70 percent of normal growth in length, or significantly less than normal control (p less than 0.001). Histologically, the thickness of the epiphyseal plate in the transplanted bone was significantly thinner than that of normal control (p less than 0.001), and earlier epiphyseal union was also noted. Hormonal alterations during adolescence are believed to have a marked effect on these findings. However, the circumferential growth of the femur and tibia was greatly affected by the loss of biomechanical stress, precluding an evaluation of the influence exerted by hormonal alterations.
The purpose of this study was the sequential evaluation of vascularized bone by quantitative analysis of bone scintigraphy with Tc-99m methylene diphosphonate (MDP). The correlation between the uptake of Tc-99m MDP and the morphologic behavior of vascularized bone was investigated, simultaneously with bone labeling, contact microradiogram (CMR), and histology of an undecalcified sample. In this experiment, 41 adult female rabbits were used. An island tibia pedicled with the popliteal vessels was used as the model of vascularized bone. The maximum uptake of Tc-99m MDP was observed at two to four postoperative weeks. When bone marrow was partially exposed, the uptake was significantly large. On the basis of this experimental study, the degree of Tc-99m MDP uptake seemed to depend primarily on the osteoblastic activity of vascularized bone. The newly-formed bone was observed mainly at periosteal sites.
In order to examine whether or not facial bones are themselves able to regulate their own growth, we devised a new experimental model in which we transplanted the whole head of an infant rat to the body of an isohistogeneic adult rat by means of microvascular anastomoses. The advantage of this model is that the transplanted head has neither scars nor any moving soft tissues that could modify growth around facial bones. Using this model, we conducted a study of the nasomaxillary region that has led us to conclude that facial bones do in fact regulate their own growth. The results also suggested that facial bone sutures play a more active role in the growth process than presently suspected.
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