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Biomedical subjects

K Hui

Publications and source records attributed to K Hui.

At least 19 recordsLinked to original sources
PubMed2001

Acupuncture effects on reflex responses to mental stress in humans.

In animal studies, acupuncture has been shown to be sympathoinhibitory, but it is unknown if acupuncture is sympathoinhibitory in humans. Nineteen healthy volunteers underwent mental stress testing pre- and postacupuncture. Muscle sympathetic nerve activity (MSNA), blood pressure, and heart rate during mental stress were compared pre- and postacupuncture. Control acupuncture consisted of acupuncture at nonacupoints and "no-needle" acupuncture. Acupuncture had no effect on resting MSNA, blood pressure, or heart rate. After real acupuncture, the increase in mean arterial pressure (pre- vs. postacupuncture 4.5 vs. 1.7 mmHg, P < 0.001), but not MSNA or heart rate, was blunted during mental stress. Similarly, following nonacupoint acupuncture, the increase in mean arterial pressure was blunted during mental stress (5.4 vs. 2.9 mmHg, P < 0.0003). No-needle acupuncture had no effect on these variables. In conclusion, acupuncture at traditional acupoints, nonacupoints, and no-needle acupuncture does not modulate baseline MSNA or MSNA responses to mental stress in normal humans. Acupuncture significantly attenuates the increase in blood pressure during mental stress. Needling nonacupoints, but not "no-needle" acupuncture, have a similar effect on blood pressure.

Acupuncture Therapy↗
PubMed2000

Free vascularized fibular bone flap in the rat.

Free vascularized fibula bone flap has been widely used in reconstruction of the mandible, long segment defect, congenital pseudarthroses, and osteomyelitis. Such applications stirred an interest in basic studies of bone biology, bone healing process, and incorporation of recipient bone defect. An experimental free vascularized fibula rat model is presented here for such investigations. We performed 16 angiograms and anatomic dissections in eight rats for collecting data on fibular length, blood supply, and the caliber of significant vessels. The fibula was harvested with part of the flexor hallucis longus muscle with an average length of 28 mm. The pedicle can be taken in continuity with the popliteal vessels (average diameter of 0.8 mm and 0.9 mm of artery and vein, respectively, with an average pedicle length of 14 mm). This vascularized fibula bone was harvested and transferred to the groin area of the same rat and anastomosed to the saphenous vessels. Twelve transplantations were performed, with a 7-day flap survival rate of 100%. The free fibula vascularized bone flap in the rat is a reliable model for further investigations.

Animals↗
PubMed2000

Free flap closure in complex congenital and acquired defects of the palate.

Extensive palatal defects cause substantial morbidity, including nasal regurgitation, poor oral hygiene, loose-fitting obturators, and difficulty with speech. Microvascular techniques allow the surgeon to repair these complex defects with a one-stage reconstruction, in contrast to possible multistage local or regional flap reconstruction. In this retrospective review, the authors present their 5-year experience with free flap coverage of extensive palatal defects. From 1993 to 1998, 6 patients underwent free flap coverage of large palatal defects. The etiology of the large palatal defects included trauma (N = 1), neoplasm (N = 4), and a recurrent congenital cleft palatal fistula (N = 1). Three patients underwent osteocutaneous radial forearm flaps and 1 patient underwent a fasciocutaneous radial forearm flap. The remaining 2 patients underwent rectus abdominis muscle flaps. The ipsilateral facial artery and vein were used as the recipient vessels in all patients. There were no intraoperative complications (surgical or anesthetic). Postoperatively, 2 patients had surgical evacuation of small flap hematomas. One patient underwent revision of the fasciocutaneous flap. All flaps survived. In our experience, the benefits of free flap reconstruction of complex palatal fistulas seem to outweigh the risks of the operation, with reliable long-term results.

Adolescent↗
PubMed2000

Economics of microsurgical cases and routine cases in a medical center.

This report describes the economic impact of microsurgical cases and routine plastic surgery cases in our medical center. The study is based on a financial analysis of the practices of two surgeons. Financial data of patient encounters (admission to the hospital or a surgical unit) identified with each surgeon were categorized into microsurgical and related cases and routine cases (including cosmetic procedures and general hand cases). Revenues, costs, and profits were tabulated. Data were analyzed for 2 fiscal years (1994-95 and 1995-96). Analysis of the first fiscal year showed that microsurgery encounters (n = 188) generated $4.4 million in revenue with a profit margin after direct costs of $2.5 million (57 percent) and a net profit, after indirect costs, of $1 million (23 percent). Routine encounters (n = 262) generated $1.7 million with a net loss of -$145,000 after direct and indirect costs. In the second fiscal year, microsurgery encounters (n = 230) had income of $4.7 million, a profit over direct costs of $2.5 million (53 percent), and a net profit after indirect costs of $0.9 million (19 percent). Routine cases (n = 202) in the same period earned $1.3 million with a net loss of -$107,000. This analysis formulates a comprehensive definition of microsurgical practice and shows that cases within this definition generated dramatically higher hospital incomes and profits compared with routine plastic surgical practice. In the circumstances of our medical center, development of this subspecialty is fiscally justifiable.

Academic Medical Centers↗
PubMed1999

The role of the plastic surgeon in the management of surgical infection.

At our Medical Center, our reconstructive service has actively sought referrals of acute and chronic infections by declaring an interest in undertaking the integrated management and reconstruction of these cases. The practices of the two senior surgeons were reviewed for three academic years (1992 to 1995). Cases of surgical infection were analyzed as to site, ablative procedures, and reconstructive procedures. In total, 139 patients with 147 infections were identified. Sites of infection included head and neck (9.5 percent), trunk and pelvis (39.5 percent), upper extremity (22 percent), and lower extremity (29 percent). One-hundred thirty-one ablative procedures were done on this group, as were 126 reconstructive procedures, including 17 fasciocutaneous flaps, 26 pedicled muscle flaps, and 28 microsurgical flaps. With a mean follow-up of 14 months, 92 percent of these patients had resolution of infection. The 8 percent failure group included recurrences, amputation, and death. This series demonstrates that a plastic surgery service can attract a diverse population of surgical infections and manage them successfully with ablation and a wide variety of reconstructive procedures. The coordination of ablation and reconstruction may be optimally performed by the plastic surgeon.

Adult↗
PubMed1998

Use of 20 cm or longer interposition vein grafts in free flap reconstruction of the trunk.

Between January of 1993 and September of 1995, six microsurgical free tissue transplants were performed using saphenous vein grafts ranging from 20 to 39 cm in length. All six free flaps survived. Two wounds were caused by radiation injury and two by tumor resection. The remaining two free flaps were performed for contour deformity and spinal cord coverage. All of the recipient sites were located on the trunk. In each case, an arteriovenous loop was created before the microvascular anastomosis to the free flap. There was one arterial thrombosis requiring thrombectomy and revision of the anastomosis. Three patients developed minor wound complications that responded to local wound care. Each of the flaps successfully provided wound coverage, and in two cases the flaps tolerated further radiation results. Long interposition vein grafts can be used for difficult microsurgical reconstructive procedures with reliable results when no local recipient vessels are available. Versatility is therefore afforded in placement of the flap and the choice of recipient vessels, making this option a useful one in the treatment of complex wounds of the trunk.

Abdomen↗
PubMed1997

Acute reconstruction of traumatic injuries of median and ulnar nerves by grafting with intercostal nerves from the rectus muscle: case reports.

In two cases of complicated hand and wrist injuries for which rectus flaps were used as soft-tissue coverage, intercostal nerves from the rectus muscles were harvested simultaneously to graft significant nerve defects. In one patient, a 7-cm ulnar-nerve defect was bridged with four intercostal nerves. The other patient had a 5-cm median-nerve defect repaired with three intercostal nerves. Both patients recovered either protective or normal sensation; and the patient with the median nerve injury recovered thenar muscle function. Intercostal nerves harvested with rectus muscle flaps can be the basis for acute grafting of nerve defects without using conventional nerve grafts at a traumatic site.

Abdominal Muscles↗
PubMed1997

Gene expression of transforming growth factor beta-1 in rabbit zone II flexor tendon wound healing: evidence for dual mechanisms of repair.

The postoperative outcome of hand flexor tendon repair can be complicated by adhesions between the repair site and surrounding tissue. To date, the biology of hand flexor tendon wound healing remains controversial--both intrinsic (resident tenocyte) and extrinsic (tendon sheath fibroblast and inflammatory cell) processes may contribute to repair. Transforming growth factor beta-1 is a cytokine that plays multiple roles in wound healing but is also implicated in the pathogenesis of excessive scar formation. This study examines the activation of transforming growth factor beta-1 mRNA in a rabbit zone II flexor tendon wound-healing model. Forty New Zealand White rabbit forepaws underwent complete transection and repair of the middle digit flexor digitorum profundus tendon in zone II. Tendons were harvested at increasing time intervals (1, 3, 7, 14, 28, and 56 days) and analyzed by in situ hybridization and immunohistochemistry to determine the expression patterns of transforming growth factor beta-1. A small number of tenocytes exhibited expression of transforming growth factor beta-1 mRNA at baseline in nonwounded control tendon specimens. The surrounding tendon sheath in these control specimens also revealed low numbers of fibroblasts and inflammatory cells expressing transforming growth factor beta-1 mRNA. In contrast, flexor tendons subjected to transection and repair exhibited increased signal for transforming growth factor beta-1 mRNA in both resident tenocytes and infiltrating fibroblasts and inflammatory cells from the tendon sheath. These data demonstrate that (1) normal unwounded tenocytes and tendon sheath cells are capable of transforming growth factor beta-1 production, (2) this cytokine is activated in the tendon wound environment, as evidenced by mRNA upregulation, and (3) the upregulation of this cytokine in both "intrinsic" tenocytes and "extrinsic" tendon sheath fibroblasts and inflammatory cells supports dual mechanisms for tendon repair. Because transforming growth factor beta-1 is thought to contribute to the pathogenesis of excessive scar formation, the findings presented here suggest that perioperative biochemical modulation of transforming growth factor beta-1 levels may help limit flexor tendon adhesion formation.

Animals↗
PubMed1996

Magnetic resonance imaging detection of vascular occlusion of a pedicled muscle flap.

Contrast-enhanced magnetic resonance imaging (MRI) can be a highly sensitive monitor of tissue blood perfusion. This technique has been used to assess blood flow through liver, kidney, and certain tumors, but has not been widely applied to the study of skeletal muscle circulation. In our study, we used a novel scanning software to obtain contrast-enhanced T2*-weighted gradient echo MRI images of pedicled quadriceps muscle flaps in rabbits in order to study images of arterial, venous, and arterio-venous occlusion. We administered an intravenous bolus of gadoteridol contrast agent at the initiation of scanning, which produces a decrease in T2*-signal and improves the sensitivity of measuring blood perfusion. Within 30 seconds of MRI scanning, control flaps with intact pedicles exhibited a rapid decrease in T2*-signal intensity, indicating adequate perfusion of blood through muscle tissue; however, occluded pedicled flaps showed no significant change in signal intensity, indicating lack of blood perfusion. Differences in signal intensities as measured by MRI between occluded and control flaps were statistically significant (P < 0.05). Selective vascular occlusion of either artery alone, or both artery and vein were detected within 15 minutes, whereas selective venous occlusion could be detected after 2 hours. We conclude that MRI has the ability to assess skeletal muscle perfusion, and is capable of noninvasively evaluating a cross-section of tissue in both superficial and buried flaps. MRI, therefore, may have the potential for evaluating perfusion in muscle flaps (including buried flaps), and other disorders of muscle circulation such as compartment syndrome.

Animals↗
PubMed1996

Femur lengthening with a vascularized tibia bone flap.

A vascularized tibial bone flap based on a single nutrient vessel has been previously proposed for use in long-bone reconstruction. While the routine use of the tibia for donor bone tissue is precluded by its essential weight-bearing function, in select cases it provides a useful alternative to standard donor bone sources. Cadaver dissection was performed to confirm the endosteal and periosteal vascular anatomy of the tibia. The presence of a consistent nutrient vessel was confirmed. Selective dye injection demonstrated a dual cortical blood supply based on both the endosteal nutrient vessel and multiple periosteal perforator vessels. Inclusion of both vascular supplies maximizes perfusion of bone and periosteum, thus potentially optimizing bone healing and osseous union. Based on these findings, the vascularized tibial bone flap was applied to a clinical case. A 45-year-old male veteran sustained a right proximal femur fracture in a motor vehicle accident. Multiple attempts at fusion with open reduction, internal fixation, grafting, and nonvascularized fibular onlay strut with cerclage wires were all unsuccessful. The patient presented with a chronic right femur nonunion with painful pseudoarthrosis; frozen knee joint; and an internally rotated, 20.3-cm shortened, nonfunctional lower limb. Femur length proximal to the nonunion was less than 15 cm. A maximum amputation stump length is recommended for optimal prosthetic function. A 15-cm pedicled tibial bone flap based on the posterior tibial endosteal and periosteal vascular supply was reversed and plated to the proximal femur to provide a stump of adequate length to optimize prosthetic fitting and function. The tibia is essential for normal weight-bearing, but in select cases may be sacrificed for use in long-bone reconstruction. Expanded use of tibial vascularized allografts in long-bone reconstruction may be made possible following future development of effective and safe immunosuppressive therapy. Transfer based on the posterior tibial pedicle, which includes the endosteal nutrient vessel as well as the periosteal supply via the tibialis posterior muscle, maximizes bone perfusion. The pedicle is of sufficient length to be used for positioning the tibia in the thigh or for free transfer to distant sites.

Amputation Stumps↗
PubMed1996

Gluteal infarction as a complication of aortofemoral bypass grafting.

Early complications following aortofemoral bypass grafting include acute limb ischemia, renal failure, bowel and spinal cord ischemia, and myocardial infarction. Although the literature recognizes these more common complications, we have found very few reports that raised the possibility of an anatomically determined, soft-tissue infarction as a complication of aortofemoral bypass grafting. Our plastic surgery service was consulted in August and October 1992 to examine 2 patients with soft-tissue complications following aortofemoral bypass grafting. Both patients were found to have complete gluteal infarction. Recognition of muscle infarction following aortofemoral grafting must be distinguished from postoperative pressure sores, since the muscle infarction requires prompt and thorough anatomic debridement to prevent in situ muscle liquefaction and sepsis.

Aged↗
PubMed1989

Synthetic peptide inhibitors of prorenin activation.

In studying potential inhibitors of prorenin activation, we synthesized stereoisomers of a nonapeptide which spans the putative prorenin cleavage site. Peptide 67 has a D-Leu substitution on the amino side of the sessile bond and peptide 68 has a D-Arg substitution on the carboxy side. Both peptides equally inhibited human urinary kallikrein activity with an IC50 of 5 x 10(-4) mol/l. However, peptide 67 inhibited tryptic prorenin activation more effectively, with an IC50 of 5 x 10(-3) mol/l, than did peptide 68 with an IC50 of 10(-2) mol/l. Although the inhibitory properties of these peptides are weak, our data suggest that peptide analogue inhibitors of prorenin activation can be developed, and that prorenin activating enzyme(s) may be another potential target of renin-angiotensin inhibition.

Amniotic Fluid↗