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Biomedical subjects

James Chang

Publications and source records attributed to James Chang.

31 records · Page 2Linked to original sources
PubMed2003

Early experience with computed tomographic angiography in microsurgical reconstruction.

Preoperative angiography is frequently used in the planning of microsurgical reconstruction. However, several potentially devastating complications can result from angiography, including arterial occlusion and pseudoaneurysm. Computed tomographic angiography is a relatively new technique that can provide detailed information about vascular anatomy as well as soft and bony tissue without the risks of traditional angiography. In addition, three-dimensional image reconstruction uniquely demonstrates anatomical relationships among blood vessels, bones, and soft tissue. Fourteen computed tomographic angiograms were obtained in 10 patients undergoing microsurgical reconstruction of the head and neck, lower extremity, or upper extremity. The average patient age was 46.9 years (range, 22 to 67 years). Charges related to the computed tomographic procedure were compared with those of conventional preoperative imaging for microsurgical repair. At our institution, the average computed tomographic angiogram charge was 1140 US dollars, whereas the average charge for traditional arteriography was 3900 US dollars. When compared with intraoperative evaluation, computed tomographic angiograms demonstrated clinically relevant surgical anatomy. No complications were noted for the radiographic procedure or after free flap reconstruction. Computed tomographic angiography provides high-resolution, three-dimensional arterial, venous, and soft-tissue imaging without the risks of traditional angiogram and at a lower cost.

Adult↗
PubMed2003

Scaphoid nonunion: diagnosis and treatment.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Understand the anatomy and pathophysiology of scaphoid fractures. 2. Understand the risk factors for scaphoid nonunion. 3. Identify treatment options for scaphoid nonunion and their respective advantages and disadvantages. 4. Identify salvage procedures for scaphoid nonunion advanced collapse of the wrist. Scaphoid nonunion is a common but difficult problem for hand surgeons. The diagnosis of scaphoid nonunion is often delayed, and therefore, treatment must be tailored to the type of fracture, the duration of nonunion, and the presence or absence of resulting arthritis. This article reviews the diagnosis and work-up of scaphoid nonunion, classification schemes for scaphoid nonunion, and various treatment options, including internal fixation, nonvascularized and vascularized bone grafting, and salvage procedures.

Arthrodesis↗
PubMed2002

Matrix metalloproteinases and the ontogeny of scarless repair: the other side of the wound healing balance.

Early gestation mammalian fetuses possess the remarkable ability to heal cutaneous wounds in a scarless fashion. Over the past 20 years, scientists have been working to decipher the mechanisms underlying this phenomenon. Much of the research to date has focused on fetal correlates of adult wound healing that promote fibrosis and granulation tissue formation. It is important to remember, however, that wound repair consists of a balance between tissue synthesis, deposition, and degradation. Relatively little attention has been paid to this latter component of the fetal wound healing process. In this study, we examined the ontogeny of ten matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in nonwounded fetal rat skin and fibroblasts as a function of gestational age. We used a semiquantitative polymerase chain reaction protocol to analyze these important enzymes at time points that represent both the scarless and scar-forming periods of rat gestation. The enzymes evaluated were collagenase-1 (MMP-1), stromelysin-1 (MMP-3), gelatinase A (MMP-2), gelatinase B (MMP-9), membrane-type matrix metalloproteinases (MT-MMPs) 1, 2, and 3, and TIMPs 1, 2, and 3. Results demonstrated marked increases in gene expression for MMP-1, MMP-3 and MMP-9 that correlated with the onset of scar formation in nonwounded fetal skin. Similar results were noted in terms of MMP-9 gene expression in fetal fibroblasts. These results suggest that differences in the expression of these matrix metalloproteinases may have a role in the scarless wound healing phenotype observed early in fetal rat gestation. Furthermore, our data suggest that the differential expression of gelatinase B (MMP-9) may be mediated by the fetal fibroblasts themselves.

Animals↗
PubMed2002

Transient response to imatinib mesylate (STI571) in a patient with the ETV6-ABL t(9;12) translocation.

We report the transient response of a patient with the ETV6-ABL fusion gene to imatinib mesylate (STI571). A 38-year-old man was referred with an erroneous diagnosis of Philadelphia-positive chronic myeloid leukemia in blastic transformation for treatment with the ABL tyrosine kinase inhibitor, STI571. Further investigation indicated that the patient in fact had acute myeloid leukemia; no evidence of the Philadelphia translocation or BCR-ABL was found using fluorescence in situ hybridization (FISH) or reverse transcription-polymerase chain reaction. Detailed FISH analysis identified a cryptic t(9;12) translocation, and molecular studies confirmed the presence of the ETV6-ABL fusion transcript. Because the patient was gravely ill at presentation, treatment was commenced immediately with STI571 monotherapy, resulting in considerable initial improvement. However within 10 days the patient's condition again deteriorated, and he required conventional chemotherapy. This case has implications for the design of future studies using STI571 in leukemias involving ABL-encoded fusion proteins other than BCR-ABL.

Acute Disease↗
PubMed2002

Autologous lymphocytes as vectors to target therapeutic radiation, using indium-114m, in patients with lymphoid cell malignancy.

Autologous lymphocytes provide a potential vector for the delivery of a cytotoxic agent in patients with lymphoid cell malignancy. This report describes a phase I-II study using autologous lymphocytes to target the radionuclide indium-114m ((114m)In) in patients with refractory chronic lymphocytic leukaemia or small lymphocytic non-Hodgkin's lymphoma. Nineteen patients, the majority of whom had been heavily pretreated with conventional chemotherapy and radiotherapy, received between 69 and 211 MBq (114m)In-labelled autologous lymphocytes. Approximately 80% of the administered activity was localized in the liver and spleen, with around 5% accumulating in the bone marrow. Ten patients (53%) responded (one complete response and nine partial responses). The median duration of response was 7 months. The median survival for the responders was 14 months and for the non-responders was 3 months. The first notable response in every patient was a fall in peripheral lymphocyte count. The indium treatment was not associated with any subjective toxicity, although all patients suffered from myelosuppression, with thrombocytopenia being the dose-limiting factor. This study has demonstrated a significant anti-tumour effect in a group of patients with late-stage highly resistant disease.

Aged↗
PubMed2002

The value of bone marrow examination in the staging of Hodgkin's lymphoma: a review of 955 cases seen in a regional cancer centre.

Bone marrow aspirates (BMA) and trephine biopsies (BMT) are commonly performed in the staging of patients with newly diagnosed Hodgkin's lymphoma (HL) but the value of these procedures is controversial. The purpose of this study was to evaluate the predictive value of the blood count and erythrocyte sedimentation rate (ESR) for bone marrow involvement (BMI) and the influence of BMI on stage and prognostic score. A retrospective analysis of 955 patients with newly diagnosed HL entered into clinical trials in a regional cancer centre between 1975 and 1999 was performed. BMI was identified by BMT in 50 patients (5.2%) but in only five of these by BMA. The negative predictive values of a normal full blood count (FBC) and ESR for absence of BMI were 98.8% and 97.3%, respectively, and the positive predictive value of an abnormal FBC and ESR for presence of BMI were both 6.7%. BMT did not alter initial patient management in a single case but provided valuable prognostic information in certain subgroups of patients. BMA gave no additional staging information over BMT and abnormalities of blood count and ESR were poor predictors of infiltration. We conclude that BMA should be abandoned for staging purposes in HL and BMT restricted to patients with stage IIB or III disease, for whom valuable prognostic information may be obtained.

Adult↗
PubMed2002

Flexor tendon healing in vitro: effects of TGF-beta on tendon cell collagen production.

Flexor tendon healing is complicated by adhesions to the surrounding sheath. Transforming growth factor beta (TGF-beta) is a cytokine with numerous activities related to wound healing. We examined the effects of TGF-beta-1, -2 and -3 on tendon cell proliferation and collagen production. Three separate cell lines--sheath fibroblasts, epitenon and endotenon tenocytes--were isolated from rabbit flexor tendons and cultured separately. Cell culture media was supplemented with 1 or 5 ng/mL of TGF-beta-1, -2, or -3. Cell number and collagen I and III production were measured and compared with unsupplemented control cultures. The addition of TGF-beta to cell culture media resulted in a decrease in cell number in all 3 lines that did not reach statistical significance. There was a significant increase (p <.05) in collagen I and III production with the addition of all 3 TGF-beta isoforms. Modulation of TGF-beta production may provide a mechanism to modulate adhesion formation clinically.

Animals↗
PubMed2002

Reconstruction of the hand in Apert syndrome: a simplified approach.

Children born with Apert acrocephalosyndactyly pose great challenges to the pediatric hand surgeon. Reconstructive dilemmas consist of shortened, deviated phalanges and extensive skin deficits following syndactyly release. We present a 10-year review of patients with Apert acrocephalosyndactyly who were treated with a simplified surgical approach. Between 1986 and 1996, 10 patients with Apert syndrome underwent reconstructive surgery of their hands. The overall strategy involved early bilateral separation of syndactylous border digits at 1 year of age, followed by sequential unilateral middle syndactyly mass separation with thumb osteotomy and bone grafting as needed. In these 10 patients, a total of 53 web spaces were released, 49 of which involved osteotomies for complex syndactyly. Only local flaps and full-thickness skin grafts from the groin were used in all cases to achieve soft-tissue coverage. To date, seven of the 53 web spaces have needed revision (revision rate, 13 percent). Eleven thumb osteotomies (nine opening wedge and two closing wedge) were performed. Bone grafts from the proximal ulna or from other digits were used in all cases. To date, none of these thumb osteotomies have needed revision. This early, simplified approach to the complex hand anomalies of Apert acrocephalosyndactyly has been successful in achieving low revision rates and excellent functional outcomes as measured by gross grasp and pinch and by patient and parent satisfaction.

Acrocephalosyndactylia↗
PubMed2002

Radiographic analysis of growth in pediatric microsurgical toe-to-hand transfers.

Microsurgical toe-to-hand transfers may provide improved hand function in children with absent digits. To date, documentation of the growth potential of these transferred digits has not been performed. This study reviewed the authors' series of pediatric toe-to-hand transfers, with specific attention paid to measuring growth by radiographic analysis. From 1995 to 2000, 23 toe-to-hand transfers were performed in 18 children. Age at time of transfer ranged from 2.8 to 13 years. Indications included constriction band syndrome, transverse deficiency, longitudinal deficiency, traumatic amputation, and vascular malformation. The transfers were successful in 22 of 23 procedures (96 percent success rate). Radiographic analysis of growth was performed using three criteria: (1) appearance of open epiphyseal plates, (2) comparison with preoperative radiographs, and (3) comparison with radiographs of the contralateral control toe. Epiphyseal plates remained open on postoperative radiographs in 27 of 28 phalanges (96 percent) at a mean of 12 months' follow-up (range, 1 to 36 months). The preoperative foot radiographs were compared with serial radiographs of the transferred toe over time. In 10 toe transfers with follow-up greater than 6 months (mean, 21 months), nine patients had increased bony length in the transferred digit. In four patients, radiographs of the toe transfer were compared with radiographs of the corresponding toe on the opposite foot. With a mean follow-up of 29 months, all patients had equal length measurements of the toe transfer with the contralateral toe control. These data provide objective evidence that digital growth potential is preserved in toe-to-hand transfers. Furthermore, this bone growth is comparable with that of the corresponding toe on the contralateral foot. Therefore, microsurgical toe-to-hand transfers may provide children with extra digits that maintain growth and improve hand function.

Adolescent↗
PubMed1998

A Method for Immobilizing the Forelimbs of Rabbits.

Immobilizing the forelimbs of rabbits after surgical procedures is necessary to allow healing, yet it often can be difficult, because rabbits are often able to pull the repaired limb from its cast soon after surgery and well before adequate tissue repair has taken place. We describe here a method of immobilization that uses 3 layers of cast material combined with flexion of the radiocarpal and radiohumeral joints. This method resulted in successful immobilization in 97% of the rabbits on which it was used.

Journal Article↗
PubMedDate not supplied

Reconstruction of hand soft-tissue defects: alternatives to the radial forearm fasciocutaneous flap.

Soft-tissue defects of the hand and wrist are not an uncommon problem confronting the hand surgeon. Over the past 20 years the retrograde radial forearm fasciocutaneous flap has gained widespread acceptance in reconstruction of these defects. Appreciation of the inherent limitations of this workhorse flap and increased understanding of the blood supply of the upper extremity have prompted the development of several alternative pedicled forearm flaps. Aspects of surgical technique, specific limitations, and indications for the radial forearm fascial flap, the posterior interosseous artery flap, the retrograde radial artery perforator flap, and the dorsal ulnar artery flap are discussed and a reconstructive algorithm for flap selection is presented.

Forearm↗
PubMedDate not supplied

Sternal osteomyelitis: use of vacuum-assisted closure device as an adjunct to definitive closure with sternectomy and muscle flap reconstruction.

OBJECTIVES: Sternal osteomyelitis following cardiac surgery often requires debridement and flap coverage. The VAC (vacuum-assisted closure) device has been useful in complex wound coverage. A retrospective review of a single surgeon's experience with sternal reconstruction using the VAC device as an adjunct to debridement and muscle flap reconstruction was performed. METHODS: Thirteen consecutive patients over a 34-month period underwent debridement and reconstruction of sternal wounds. Eleven patients (85%) were males, and two (15%) were females. Mean age was 61 years (range: 43-73 years). Acute purulent sternal infections occurred in seven patients, while chronic sternal osteomyelitis was seen in six patients. Use of the VAC device during the perioperative period was evaluated. RESULTS: Of the 13 patients, the VAC device was used prior to flap closure in six patients, and after flap closure in two patients. Sternal debridement with bilateral pectoralis muscle flaps was used to reconstruct 12 patients, and one patient underwent debridement only with VAC placement. All 13 patients (100%) had complete closure of their complex wounds at an average of follow-up of 14 months. CONCLUSIONS: The VAC device is useful in the treatment of sternal osteomyelitis in three contexts: (1) as a temporary wound care technique preoperatively that minimizes dressing changes and prevents shear stresses of an open sternum, (2) as the sole method of wound closure in specific cases, and (3) as a technique to facilitate healing in postoperative flap reconstruction cases complicated by reinfection.

Adult↗