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Biomedical subjects

J G Yan

Publications and source records attributed to J G Yan.

At least 19 recordsLinked to original sources
PubMed2000

Hyperbaric oxygen: a means of decreasing ischemic epiphyseal damage in a pediatric rabbit model.

The effect of hyperbaric oxygen on epiphyseal ischemia was evaluated using a pediatric rabbit model. Forty-five animals were compared in this study: 23 from a control pilot study and 22 hyperbaric exposed animals. In each animal the right distal femoral and proximal tibial epiphyses were isolated on a popliteal vascular pedicle. The left leg acted as the control. The growth difference between the rabbit's hindlimbs was the means of comparison throughout the groups established. Warm ischemia was induced by applying a vascular clamp to the right popliteal artery for 12 hours (20 animals) and 7 hours (17 animals). The remaining 8 animals underwent a sham operation without interruption of epiphyseal perfusion. On completion of the ischemic period hyperbaric oxygen therapy (HBOT) was performed on 12 12-hour (12h-HBOT) and 10 7-hour (7h-HBOT) animals at 2 atmospheres for 90 minutes twice per day for 4 postoperative days. The animals were killed on either postoperative day 14 or 90. Measurement of longitudinal bone growth was performed on the 90-day animals from serial radiographs at the time of surgery and then at 1 month, 2 months, and 3 months after surgery. There was no significant difference in longitudinal bone growth between the sham-operated and the 7h-HBOT animals at 1, 2, and 3 months. There was a statistically significant difference, however, between the normal growth of the 7h-HBOT group compared with the abnormal growth of the 7-hour, 12-hour, and 12h-HBOT animals. Histology was consistent, with the bone growth data demonstrating relative normalcy of the 7h-HBOT group epiphyseal plates versus severe architectural aberrance and necrosis of the 12h-HBOT group epiphyses. Our experimental data indicate that a clinical trial should be instituted using HBO for pediatric replantation patients when warm ischemia exceeds 7 hours. (J Hand Surg 2000; 25A:159-165.

Analysis of Variance↗
PubMed1998

The detailed anatomy of the palmar cutaneous nerves and its clinical implications.

The forearms and hands of 40 fresh-frozen cadavers were dissected under the microscope to study the palmar cutaneous branch of the median nerve (PCBm) and the palmar cutaneous branch of the ulnar nerve (PCBu). Branches of the PCBm innervating the scaphoid were typically found, but in no specimen did we find a 'typical' cutaneous branch of the ulnar nerve. According to our findings, standard incisions for open carpal tunnel release carry a significant risk of damaging branches of the PCBm or PCBu. The chance of injury to these sensory nerves can be minimized by using a short incision in the proximal palm or a twin incision approach, which we describe. Because the PCBm is closely associated with the ulnar side of the flexor carpi radialis (FCR) sheath, this sheath should be opened on the radial side during harvest of the FCR tendon for transfer. When transferring the palmaris longus tendon, it should be cut proximal to the distal wrist crease to avoid possible damage to the PCBm.

Cadaver↗
PubMed1998

A prefabricated free flap for eyelid reconstruction.

Patients with severe soft-tissue trauma to the ipsilateral upper and lower eyelid and surrounding structures represent a reconstructive challenge. The authors present a new approach to eyelid reconstruction, by creating a prefabricated free flap from the contralateral lower eyelid. New Zealand white rabbits were anesthetized, and the central artery and vein of the ear were mobilized and placed in a subcutaneous tunnel in the lower eyelid. After a delay procedure, flaps were made that measured 50 percent of the lower lid area. In an initial group (n = 9), the flaps were harvested at 3 weeks, and injected with Microfil, to demonstrate visual and radiologic patency and perfusion from the neopedicle. In a subsequent group of animals (n = 6), full-thickness defects of 50 percent of the left upper lid were created. Prefabricated free flaps from the right lower lid were transferred, anastomosing to the central artery and vein on the side of the eyelid being reconstructed. Tissue removed from the upper eyelid was placed in the defect of the lower lid donor site to serve as a control. Flaps were followed for periods of up to 6 months, documenting results photographically and by injection. Prefabricated free flaps from the lower eyelid maintained long-term patency and full-thickness perfusion from the pedicle, and also maintained size, shape, and accessory skin appendages better than composite graft controls. The authors concluded that prefabricated free flaps may be used to reconstruct eyelid defects; a surgical technique for application to human subjects is proposed.

Animals↗
PubMed1997

Anatomy of the intermetacarpal ligaments of the carpometacarpal joints of the fingers.

In this study, the structure of the retaining ligaments between the proximal metacarpal bones of the fingers was defined. Anatomic dissections were performed on 10 fresh cadavers. Four separate ligaments were found: a dorsal metacarpal ligament, a palmar metacarpal ligament, and 2 interosseous ligaments oriented in a V-shaped configuration. The V-shaped interosseous ligaments were found to be the strongest; along with the palmar and dorsal intermetacarpal ligaments, they form a very strong connection between the bases of the adjacent metacarpals.

Carpal Bones↗
PubMed1994

Entrapment of posterior interosseous nerve of forearm. Report of 25 cases.

Of the 25 cases of entrapment, or compression syndrome of the posterior interosseous nerve of the forearm reported, 23 were treated surgically. The compressing or entrapping factors found during the operations consisted of 14 sites in tendinous tissues, 12 in vessels, 6 in scar adhesions, and 3 unclear. Of 11 cases each had 2 or more compression sites. 19 patients underwent local decompression. And 4 cases had membranous and degenerated nerves resection and end-to-end anastomoses. Hypertrophy and inflammation appeared to be the main pathological changes in 10 cases. The causes and pathology are discussed and the early diagnosis and treatment emphasized.

Adolescent↗
PubMed1993

Toe-to-hand transfer: an analysis of 14 failed cases.

Fourteen failed cases of 325 patients who had undergone the operation of toe-to-hand transfer to reconstruct the thumb and/or the finger are reported. Five key factors were related to the survival of the transferred toe: two sets of arterial blood supply in the case of an arterial anomaly, the resection of diseased vascular segments, the observation of capillary blood refill for the judgment of circulatory crisis, and the prevention and treatment of a hypercoagulable state.

Adult↗
PubMed1993

Free toe transfer for thumb and finger reconstruction in 300 cases.

From 1966 to 1989, we performed free toe transfer for thumb and finger reconstruction in 300 patients, with 286 survivals and 14 failures, a total survival rate of 95.55 percent. Follow-up for 2 to 23 years showed that movement and sensation of the reconstructed thumbs and fingers were satisfactory in all of the 286 cases. The optimal indications for the operation were defect of the thumb at the plane of the metacarpophalangeal joint and defects of the second to fifth fingers. Besides atraumatic isolation of the second toe and sophisticated microsurgical suturing technique, special attention was paid to intraoperative vascular variations, to providing the double arterial blood supply system if necessary, and to the identification and management of postoperative circulatory crisis.

Adult↗
PubMed1992

Seventh cervical nerve root transfer from the contralateral healthy side for treatment of brachial plexus root avulsion.

Cervical root nerve transfer from the contralateral side has been used for the treatment of brachial plexus root avulsion in 49 patients. Resection of C7 root from the healthy side has produced no long-term symptoms or signs. Nine patients with ten recipient nerves have been followed up for more than two years and seven have obtained a functional recovery. This operation offers a new approach for the treatment of brachial plexus root avulsion.

Adolescent↗
PubMed1991

Cervical nerve root transfer from contralateral normal side for treatment of brachial plexus root avulsions.

The authors had designed cervical root nerve transfer from the contralateral normal side for the treatment of brachial plexus root avulsions in August 1986. Since then, the operation was performed in 50 cases. Follow-up studies showed that resection of C-7 root from the healthy side produced no long-term ill effect except numbness and pain of the fingers and weakness of gripping strength shortly after the procedure. In 10 recipient nerves of 9 cases with follow-ups of more than 2 years, satisfactory results were seen in 7. This is a new approach for the treatment of persistent cases of brachial plexus avulsion.

Adolescent↗
PubMed1990

[Microstructure of tendon and its clinical significance].

Superficial and internal-structure of human and rat tendons were investigated under scanning electronic microscopy. Histologically, there are many pores on the synovium, under which a layer of network of fiber bands wraps the tendon. The synovial fluid propulsion system includes: Synovium----pores----network of fiber bands----space of tendon bands----space of tendon fibers. The synovial fluid is propelled through the above structure. The function of the network structure is like a sponge, it has the function of nutrition, absorption of heat, and lubrication.

Animals↗
PubMed1990

Root avulsion of brachial plexus in infants and children.

Twenty-one patients, under 6 years of age, with root avulsion of the brachial plexus were treated from 1975 to 1987. Among them, 9 had root avulsion of the upper trunk, 2 root avulsion of the lower trunk with middle trunk broken, and 10 root avulsion of the whole brachial plexus. Follow-up of 16 patients showed excellent results in 2 patients, good in 11, fair in 1 and poor in 2. It is suggested that good results can be obtained if multi-paired nerve transfer is adopted in treatment. We conclude that owing to anatomical and physiological characteristics of the respiratory system in children, it is harmful to perform phrenic nerve transfer concomitantly with intercostal nerve transfer. Advisably, two-stage operation is required, otherwise dyspnea and pneumonia are liable to occur. In addition, the time of the operation could be extended to 4-5 years after injury in children, but best results are obtained if the operation is performed within 1 year.

Accidents, Traffic↗
PubMed1990

[Experimental study of activity of vessels in the smooth muscles and changes in Ca(++)-ATPase following transplantation of severed limb in rats].

240 Wistar rats were divided into 3 groups to study the postoperative activity of smooth muscle of the anastomosed vessel and the response of it to mechanical and chemical (nor-adrenaline) stimuli, together with the changes of Ca(++)-ATPase following transplantation of the severed limb. The results showed that the post-operative circulatory crisis could set in 3 definite periods with different causes: (1) paralytic period: Within the first 48 hours after operation, no vascular spasm could be provoked anyhow. Should circulatory crisis be found, thrombosis is the most likely cause and prompt surgical exploration with appropriate management is mandatory. (2) Hypersensitive period: 49 to 96 hours after operation, following re-establishment of circulation, the smooth muscle of the vessel, having been recovering in function and in ultrastructure from pathological changes, retains its contractability; while Ca(++)-ATPase, a vascular relaxator, has not yet resumed to be active; the vessel becomes hypersensitive to stimuli of any kind. In case of circulatory crisis, vessel spasm is probably the rule. Conservative management with anti-spasmodic drugs is the treatment of choice. (3) recovery period: 97 to 240 hours after operation, both the anatomical structure and biological activity of the smooth muscle have returned normal and, the Ca(++)-ATPase has also come to play. So that the smooth muscle of vessel resumes its normal function and becomes relatively stable. However, possibility of vascular spasm exists until the tenth post-operative day has passed.

Animals↗
PubMed1990

[Transmission electron microscope observation of morbid nerve segments in neurocausalgia].

The authors report the observations by TEM of morbid nerve segment from 3 cases of typical neurocausalgia. It was discovered that a lot of collagen fibrils proliferation, myelin sheaths compressed partly or completely disintegrated and exposed axons. A great number of no myelinic nerve fibers, remained and a great number of macrophages were present, which are morphological characteristics of neurocausalgia.

Adult↗
PubMed1989

Phrenic nerve transfer for brachial plexus motor neurotization.

We report a series of 164 patients who underwent phrenic neurotization to elements of the brachial plexus with root avulsion injuries. Recipient nerves included musculocutaneous nerve in 125 patients (78 direct neurotizations and 48 with intervening autograft), median nerve in 10 patients, and a variety of other nerves in 28 patients. Sixty-five patients presented a follow-up period of 2 or more years. Of this group, 55 patients (84.6%) achieved a recovery of M-3 or better. We observed no long-term deleterious effects on respiratory function.

Adolescent↗
PubMed1989

Arterialized free flap. Report of four cases.

In 1985, we applied an arterialized vein stem free flap in 4 cases with success in 3. In making this flap the superficial vein with the covered skin of the limb was used. In operation the flap was inverted and the 2 ends of the vein stem were anastomosed with the artery of the recipient area. Rapid arterial blood flow not only provided blood supply to the flap, but through the "venous network shunt" and "tidal pressure difference of artery" maintained blood circulation of the flap. The details of technique and the changes of blood circulation after flap transfer are described, as are indications advantages and mechanism of blood circulation of the flap, and factors affecting the circulation.

Adolescent↗
PubMed1989

Microsurgical treatment of brachial plexus irreversible avulsion.

A new combined measure of nerve transfer, including antebrachial medial cutaneous nerve, and free musculocutaneous flap transfer was applied to the treatment of irreversible avulsion of the brachial plexus. 12 patients underwent this operation for restoring elbow and finger flexion. Good result was obtained in 71% for elbow and 60% for finger flexion restoration. The definition of irreversible avulsion and the methods, key points and value of the operation are described and discussed in detail.

Brachial Plexus↗