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Biomedical subjects

W C Wu

Publications and source records attributed to W C Wu.

At least 55 records · Page 3Linked to original sources
PubMed1999

Management of severe proliferative vitreo-retinopathy with perfluorocarbon liquids and silicone oil.

12 patients of retinal detachment with advanced proliferative vitreoretinopathy were managed with intraoperative perfluoro-N-octane and postoperative silicone oil injection from March 1994 to June 1996 in Kaohsiung Medical University Hospital. The combined intraoprative procedures included posterior vitrectomy (12 eyes), membrane peeling (12 eyes), lower peripheral iridectomy (8 eyes), endo-photocoagulation (8 eyes), retinotomy (8 eyes), and retinal fixation with tack (1 eye). After a minimum of 10 months of follow up, the retina was successfully reattached in 10 (84%) of the 12 eyes, 5 of these eyes had stable tractional detachments on the anterior part of the scleral buckle. Seven patients (58.3%) regained vision of 5/200 or better. The rate of improvement by listing best corrected visual acuity after operation was 75%. We think that the ability to readily remove additional pre-retinal fibrous tissue after the retina was flattened with perfluorocarbon liquids allowed the surgeon to perform a further complete membrane dissection. It can therefore improve the success rate of surgery and hence decrease the rate of complications that was previously thought to be caused by sillicone oil.

Fluorocarbons↗
PubMed1999

Surgical outcome of combined phacoemulsification and trabeculectomy.

BACKGROUND: A retrospective study was undertaken to evaluate the results of phacoemulsification, intraocular lens implantation, and trabeculectomy in patients with cataracts coexisting with glaucoma. METHODS: This study consisted of 20 eyes from 19 patients. Fifteen eyes had chronic angle-closure glaucoma and 5 eyes had primary open-angle glaucoma. All cases were followed for a minimum of 6 months (range, 6 to 16 months). The mean preoperative intraocular pressure (IOP) was 17.3 +/- 4.5 mmHg. The mean preoperative visual acuity was 0.05 +/- 0.19. The mean number of preoperative antiglaucoma medications per patient was 2.3. RESULTS: Postoperatively, all patients except for one no longer required antiglaucoma medication. The mean IOP was 10.7 +/- 3.7 mmHg one month postoperatively and 13.7 +/- 4.3 mmHg at the final follow-up visit. Vision improved in 80% of the patients and remained unchanged in 20%. The failure to achieve improvement was due to advanced optic atrophy. The mean level of surgically induced astigmatism at the final visit was 0.98 +/- 0.91 diopters as calculated by vector analysis. Various extents of fibrin exudate was found in 10 eyes (50%). The most serious postoperative complication, occurring in one eye (5%), was temporary hypotony with moderate choroidal effusion, which later resolved spontaneously. CONCLUSION: Combined phacoemulsification and trabeculectomy is an effective and safe approach for obtaining good visual rehabilitation and glaucoma control.

Aged↗
PubMed1998

Concomitant tuberculosis and pyogenic infection of the cervical spine. A case report.

STUDY DESIGN: This case report describes a middle-aged woman with concomitant tuberculosis and pyogenic infection of the cervical spine. OBJECTIVE: To describe an unusual case of concomitant tuberculosis and pyogenic infection of the cervical spine. SUMMARY OF BACKGROUND DATA: Neither tuberculosis nor pyogenic spondylitis of the cervical spine is a common disorder. This case report describes a concomitant infection of C3-C4 in an otherwise healthy patient. To the authors' knowledge, such a case has never been reported. METHODS: This 52-year-old woman had spontaneous neck pain and myelopathy. Radiologic examination revealed the presence of an epidural abscess with destruction of C3-C4 vertebral bodies. RESULTS: Anterior decompression and fusion were performed, followed by therapy with antituberculosis drugs and antibiotics. The patient completely recovered. A follow-up radiograph revealed that solid fusion had been achieved. CONCLUSION: A case of concomitant tuberculosis and pyogenic infection of the cervical spine is presented. The possibility of this differential diagnosis should be considered, especially in areas of endemic tuberculosis. Examination of biopsy samples for histologic and bacteriologic findings is important to confirm this diagnosis. Radical debridement and combination therapy are strongly recommended to treat patients with this combination of infections.

Abscess↗
PubMed1998

Fusion of the lumbar spine with a free vascularized fibular bone graft: case report.

Spinal fusion with either non-vascularized or vascularized bone grafts has been well documented for inflammatory, degenerative, post-oncological and post-traumatic reconstruction Vascularized bone graft has been proven to have more rapid healing and better clinical results. A few reports have indicated that free vascularized fibular bone grafts have been used for reconstruction of the cervical and thoracic spine with good clinical results. We report a case of a third lumbar vertebra burst fracture successfully treated with a free vascularized fibula graft after failure of an initial conventional bone graft. The neurological symptoms improved significantly. The strong and straight bone quality makes the vascularized fibula an ideal choice for reconstruction of the spine. Vascularized fibula bone graft is an option in cases with failed nonvascularized bone grafts, in cases where an iliac bone is not suitable for reconstruction, or in cases where a poor recipient bed makes having well-vascularized bone necessary. This report describes our surgical approach and demonstrates the versatility of the free fibular osteoseptocutaneous flap for reconstruction of any portion of the spine.

Adult↗
PubMed1998

Spike responses of sympathetic vertebral nerve activities during stimulation of the pressor dorsomedial and rostral ventrolateral medulla differ in cats.

In this study, we developed a differential integrator unit containing a window discriminator (WPI-121) and three integrators (sample/hold, Gould) to characterize the difference in spikes involved in sympathetic vertebral nerve activity (VNA) and integrated VNA (Int. VNA) during stimulation of the dorsomedial (DM) and rostral ventrolateral (RVLM) medullar. The upper level (UL) in the window discriminator was set at a value, 80% of the VNA amplitude above the zero. The low level (LL) was set at a value 10% above the zero. The number of VNA spikes above the UL in the window discriminator was defined as Fa, while the number of VNA spikes within the UL and LL as Fw. In 26 cats anesthetized with urethane and alpha-chloralose, results showed that electrical stimulation and microinjections of glutamate (Glu, 0.25 M, 50 nl) or glycine (Gly, 1.0 M, 50 nl) at the same point in DM or RVLM increased both systemic arterial pressure (SAP) and Int. VNA. However, the increase of Int.VNA on DM stimulation was contributed by increases of both Fa and Fw, while on RVLM stimulation the increase of Int.VNA was mainly contributed by the increase of Fa, against a decrease of Fw. As compared to Glu, stimulation of DM by Gly produced more increase in Fw, while stimulation of RVLM by Gly produced more decrease in Fw. During RVLM stimulation the VNA was usually transferred to a huge synchronized oscillation. These findings suggest that although stimulations of the sympathetic-pressor neurons in DM and RVLM produce similar increases in SAP and VNA, the nature of these neurons is different.

Action Potentials↗
PubMed1997

Glycine increases arterial pressure and augments NMDA-induced pressor responses in the dorsomedial and ventrolateral medulla of cats.

The present study is designed to determine and characterize two neurobiological events. Firstly, we investigated whether increases of systemic arterial pressure (SAP) and sympathetic vertebral nerve activity (VNA) produced by microinjection of glycine (Gly) in the dorsomedial (DM) or rostral ventrolateral medulla (RVLM) are mediated by pressor neurons in DM or RVLM. Secondly, we assessed whether simultaneous microinjections of Gly and N-methyl-D-aspartate (NMDA) in DM or RVLM potentiate the NMDA-pressor effects. Changes in SAP and VNA were recorded in 33 cats under alpha-chloralose and urethane anesthesia. Microinjection of sodium glutamate (Glu, 0.25 M, 30 nl) or Gly (1.0 M, 30 nl) into the DM or RVLM increased SAP and VNA in similar magnitude. Latencies of changes in SAP and VNA induced by Gly, however, were longer (3 s) than those induced by Glu. Prior microinjection of the following antagonists blocked the Gly-induced pressor responses: 2-amino-5-phosphonopentanoate (AP-5, 25 mM, 30 nl), a specific NMDA receptor antagonist; or glutamate diethyl ester (GDEE, 0.5 M, 30 nl), a quisqualate receptor antagonist; or kynurenic acid (KYN, 10 mM, 30 nl), a broad spectrum competitive Glu antagonist. Prior treatment with strychnine (3 mM, 30 nl), a specific Gly antagonist, also blocked the Gly-induced pressor responses. Since Gly is believed to be an inhibitory neurotransmitter, these data suggest that Gly may produce pressor actions via an inhibition on specific inhibitory neurons synapsing with the pressor neurons. NMDA (0.1 M, 30 nl) and Gly (1.0 M, 30 nl) microinjected simultaneously in DM or RVLM produced a greater pressor action than NMDA alone. This potentiation was blocked by KYN, another known antagonist for such potentiation, but was only partially blocked by strychnine.

2-Amino-5-phosphonovalerate↗
PubMed1997

Attenuation of cardiovascular reactions of vocalized and non-vocalized defence areas of periaqueductal grey following lesions in dorsomedial or ventrolateral medulla of cats.

In the pretentorial periaqueductal grey (PAG), the region producing pressor responses, vocalization and other somatic and visceral signs (VPR) of the defence reaction and another region producing pressor responses (PR) were localized by electrical stimulation in adult cats, anesthetized with intraperitoneal chloralose (40 mg/kg) and urethane (400 mg/kg). The pressor responses included increases of systemic arterial pressure (SAP) and heart rate, increases of blood flow in the common carotid and femoral arteries and a decrease of blood flow in the superior mesenteric artery. The VPR was found in a relatively restricted region of the dorsolateral PAG, while PR was found scattered within the dorsal and ventral portions of the lateral PAG. The increase of SAP and the changes of blood flow in the sampled arteries were slightly greater during VPR than PR stimulation. Mild vocalization with a slight increase of SAP but marked increases of carotid and femoral blood flow (vasodilation) could be induced by microinjection of N-methyl D-aspartate (0.2 M, 200 nl) into the VPR and the blood flow increase, particularly that of the femoral artery, was greatly attenuated by atropine (1 mg/kg, i.v.). In order to ascertain the contribution of the medullary pressor areas to the VPR- and PR-induced responses, extensive lesions were made in the dorsomedial (DM) or vetrolateral medulla (VLM) by microinjections of kainic acid (KA, 0.024 M) in 27 of the 42 cats. The resting SAP and blood flow of the three arteries were reduced by lesioning of the VLM more than that of the DM. Responses of SAP and blood flow from activation of the PR and VPR, particularly the latter, were affected more after DM compared to VLM lesioning. These data suggest that, while the pretentorial PAG constitutes the 'defence area,' vocalization is confined exclusively to its dorsolateral region and that both the VLM and DM contribute to the cardiovascular components of defence reactions. The DM appears to have a greater contribution compared to the VLM.

Animals↗
PubMed1997

Use of dynamic capillaroscopy for studying cutaneous microcirculation in patients with diabetes mellitus.

To investigate the relationship between cutaneous microcirculation and retinopathy in diabetes mellitus, we studied by dynamic capillaroscopy 35 diabetes mellitus patients, including 10 patients without retinopathy, 10 patients with background retinopathy, and 15 patients with proliferative retinopathy. We found that (1) cutaneous and retinal microcirculation in diabetes mellitus in long-term diabetes mellitus, regressional rather than proliferational changes occurred in skin vasculature as compared to that in retina; (2) functional impairments of cutaneous microcirculation, that is, decreased resting capillary blood cell velocity, peak blood cell velocity, and prolonged time to peak capillary blood cell velocity by dynamic capillaroscopy, could be detected in diabetes mellitus patients without retinopathy; (3) the degree of tortouosity of capillaries, impairment in peak capillary blood cell velocity, and time to peak capillary blood cell velocity of cutaneous microcirculation were significantly correlated with the gravity of retinopathy in diabetes mellitus patients; (4) abnormal leakage of fluorescence in cutaneous microcirculation appeared in diabetes mellitus patients with or without abnormal fluorescein angiography in retina. In conclusion, dynamic capillaroscopy used in concert with ophthalmoscopy and fluorescein angiography can facilitate a comprehensive examination of vasculopathy in diabetes mellitus.

Adult↗
PubMed1997

Propofol inhibits medullary pressor mechanisms in cats.

PURPOSE: Propofol may cause hypotension and the mechanism is complex. The present study was designed to determine the direct actions of propofol in medulla of cats. METHODS: Mean systematic arterial pressure (MSAP), heart rate (HR) and cardiac contractility (dp/dt) were compared before and after administration of propofol the femoral vein (2, 3, or 4 mg.kg-1), vertebral artery (1 mg.kg-1) or the lateral cerebral ventricle (0.5 mg.kg-1) in eight anaesthetized cats. To study the direct effect of propofol in medulla, pressor areas of the dorsomedial medulla (DM) and rostral ventrolateral medulla (RVLM), or the depressor area of the caudal ventrolateral medulla (CVLM) were first identified with electrical stimuli and then confirmed by pressure microinjection of glutamate (Glu, 0.25M, 30 nl) via a multibarrel-micropipette in 28 cats. One hour later, propofol (0.001%, 50 nl) was microinjected at the same site. Electrical stimulation and Glu were applied again to compare changes of SAP, HR and dp/dt with that of the control. RESULTS: Propofol dose-dependently decreased SAP, HR and cardiac contractility. The percent increase of MSAP induced by Glu were reduced by propofol in DM (59 +/- 3% vs 13 +/- 2%, n = 11, P < 0.01) or in RVLM (56 +/- 4% vs 18 +/- 2%, n = 9, P < 0.01). In CVLM, propofol slightly but not significantly increased depressor responses elicited by Glu (-27 +/- 2% vs -33 +/- 3%, n = 5, P > 0.05). CONCLUSION: Our results show that propofol principally inhibits the vasomotor mechanism in the dorsomedial and ventrolateral medulla to effect its hypotensive actions.

Anesthetics, Intravenous↗
PubMed1997

The combined use of flaps based on the subscapular vascular system for limb reconstruction.

The combined use of flaps based on the subscapular vascular system for limb reconstructions has been infrequently reported. Such combinations have mainly been used for mandibular and facial reconstructions. We have used these flaps as free flaps for lower limb reconstructions in 7 patients, in 6 cases after trauma and in one after infection. A latissimus dorsi muscle or musculocutaneous flap and serratus anterior muscle flap were used together in 4 cases, and a latissimus dorsi muscle flap and parascapular flap in 3 cases. All cases healed satisfactorily. The indications for the combined use of these flaps are to resurface two separate defects simultaneously or to resurface very large defects. The anatomy of the subscapular vascular system allows the combined use of two or more flaps. It has the advantage of requiring anastomosis of one vascular pedicle only. Such combined flaps are particularly suitable for resurfacing defects wider than their length in relation to the long axis of the limb.

Adult↗
PubMed1997

Evidence of a direct projection from the cardiovascular-reactive dorsal medulla to the intermediolateral cell column of the spinal cord in cats as revealed by light and electron microscopy.

To ascertain whether the dorsal medulla, a well-established vasopressor structure, would project directly to the sympathetic intermediolateral cell column of the spinal cord, we have carried out both anterograde and retrograde tracing studies in cats. For anterograde tracing, biotin-dextran was iontophoretically delivered into the cardiovascular-reactive dorsal medulla following its functional identification by electrical stimulation. The anterogradely transported biotin-dextran was then visualized using the avidin-biotin-horseradish peroxidase complex method. By light microscopy, dextran-labelled varicose axons were observed bilaterally in the intermediolateral nucleus extending from segments T1 to L3, but concentrated in segments T1-T5, notably at levels T2-T4. Electron microscopic examination revealed the localization of biotin-dextran reaction product in some small myelinated axons and axon terminals in the intermediolateral cell column. The majority of tracer-labelled axonal boutons contained spherical synaptic vesicles and made asymmetric synaptic contacts primarily with small dendrites. A few boutons contained polymorphic synaptic vesicles and tended to form symmetric axodendritic synapses. Spinally projecting neurons of the dorsal medulla were identified using the retrograde transport of horseradish peroxidase injected into the electrically cardiovascular-reactive intermediolateral nucleus. The labelled neurons were localized in the medullary dorsomedial reticular formation ventromedial to the nucleus of the solitary tract, approximately 0.5-5 mm rostral to the obex. The projection was bilateral, but was relatively denser in the rostral portion of the contralateral dorsal medulla. The present findings support the hypothesis that the dorsal medulla, through its direct pathway innervating the intermediolateral nucleus, may serve as a sympathetic premotor structure for regulation of arterial pressure.

Animals↗
PubMed1997

Daily omeprazole surpasses intermittent dosing in preventing relapse of oesophagitis: a US multi-centre double-blind study.

INTRODUCTION: Relapse of erosive oesophagitis occurs in almost all patients if treatment is stopped after initial healing. AIM: To assess the potential of different therapeutic regimens of omeprazole to prevent relapse of erosive reflux oesophagitis after initial healing with omeprazole. PATIENTS AND METHODS: Patients whose active erosive reflux oesophagitis (grade > or = 2) had healed (grade 0 or 1) after 4-8 weeks of open-label omeprazole 40 mg daily (phase I) were eligible to join a multi-centre, 6-month double-blind, placebo-controlled maintenance study (phase II), which included endoscopy, symptom assessments, serum gastrin measurements, and gastric fundic biopsies. During phase I, endoscopy was performed at weeks 0, 4, and 8. At the end of phase I, 429 of 472 patients (91%) were healed, and there were significant reductions in heartburn, dysphagia and acid regurgitation. Of the 429 patients who healed, 406 joined phase II and were randomized to one of three groups: 20 mg omeprazole daily (n = 138), 20 mg omeprazole for 3 consecutive days each week (n = 137), or placebo (n = 131). During phase II, endoscopy was performed at months 1, 3, and 6 or at symptomatic relapse. RESULTS: The percentages of patients still in endoscopic remission at 6 months were 11% for placebo, 34% for omeprazole 3-days-a-week, and 70% for omeprazole daily. Both omeprazole regimens were superior to placebo in preventing recurrence of symptoms (P < 0.001); however, omeprazole 20 mg daily was superior to omeprazole 20 mg 3-days-a-week (P < 0.001). Compared to baseline, omeprazole therapy resulted in no significant differences among treatment groups in the distribution of gastric endocrine cells. CONCLUSIONS: These results show that after healing of erosive oesophagitis with 4-8 weeks of omeprazole, relapse of oesophagitis and recurrence of reflux symptoms can be prevented in 70% of patients with a maintenance regimen of 20 mg daily, but that intermittent dosing comprising 3 consecutive days each week significantly compromises efficacy.

Anti-Ulcer Agents↗
PubMed1997

Diagnostic criteria for pseudomalignant osteoblastoma.

AIMS: Osteoblastoma is a rare bone tumour and differentiation from osteosarcoma is occasionally a diagnostic problem. The difficulty is further compounded when such a lesion microscopically shows cytological or architectural atypia. METHODS AND RESULTS: A case of pseudomalignant osteoblastoma occurring in the left iliac crest of a 34-year-old Chinese woman is presented. Radiographic findings were non-diagnostic, but favoured a benign yet locally aggressive lesion. Histologically the diagnosis was based on the findings of classical osteoblastoma areas harbouring pseudomalignant osteoblasts in the absence of mitoses, but there were co-existing atypical architectural features also. CONCLUSION: The significance and pathogenesis of the 'permeative pattern' are discussed. Difficulties in differentiating borderline lesions are emphasized.

Adult↗
PubMed1997

Reversed arterial flow in free flap surgery for leg reconstruction.

A lower leg open fracture with an accompanying extensive soft-tissue defect may require free flap transfer to resurface the wound. In open-leg fracture injuries the major arteries are frequently damaged during the injurious event. When the antegrade arterial blood flow is not available for arterial inflow to the free flap, end-to-side arterial anastomoses or a venous graft from a proximal healthy artery is an appropriate solution. Reversed arterial flow is another technique that may be used to provide arterial inflow to the free flap. We report 5 patients with open tibial fracture injuries that were successfully covered using latissimus dorsi muscle free flaps with reverse arterial inflow and either antegrade venous outflow (4 patients) or retrograde outflow (1 patient). This technique is indicated when (1) the defect is not located at the site adjacent to the residual antegrade artery, (2) a long vein graft might pass through severely scarred soft tissue, or (3) after failure in end-to-side anastomosis with accompanying insufficient antegrade proximal arterial flow but good distal arterial reflux.

Adolescent↗
PubMed1997

Involvement of non-NMDA and NMDA receptors in glutamate-induced pressor or depressor responses of the pons and medulla.

1. Fifty-five intact and six baroreceptor denervated and vagotomized cats of either sex were anaesthetized intraperitoneally with urethane (400 mg/kg) and alpha-chloralose (40 mg/kg). Responses of the systemic arterial pressure (SAP), mean SAP (MSAP) and sympathetic vertebral nerve (VNA) and renal nerve activities (RNA) were recorded. 2. In intact animals, monosodium L-glutamate (Glu, 0.1 mol/L, 50 nL) was microinjected into pressor areas of the locus coeruleus (LC), gigantocellular tegmental field (GTF), rostral ventrolateral medulla (RVLM) and dorsomedial medulla (DM), and the depressor areas of caudal ventrolateral medulla (CVLM). The induced actions were compared before and after microinjection of either glutamate antagonists, glutamate diethylester (GDEE, 0.5 mol/L, 50-100 nL), a competitive AMPA receptor blocker, or 2-amino-5-phosphonovaleric acid (D-AP5, 0.025 mol/L, 50-100 nL), a competitive N-methyl-D-aspartate (NMDA) receptor blocker. GDEE completely blocked the increases of SAP and VNA elicited from all pressor areas. D-AP5 only partially blocked the pressor but slightly blocked VNA and RNA responses from LC, GTF and DM, particularly those from RVLM. Neither GDEE nor D-AP5 blocked the depressor responses of SAP and two nerve activities elicited from CVLM. 3. In baroreceptor denervated animals, NMDA (2 mmol/L, 50-100 nL) and AMPA (0.2 mmol/L, 50-100 nL) were micro-injected into the same pressor areas of GTF, RVLM and DM and the depressor area of CVLM responsive to Glu activation (0.1 mol/L, 30 nL). In RVLM, DM and CVLM, the results of either NMDA or AMPA were similar to those induced by Glu. However, in GTF, microinjection of either NMDA or AMPA did not induce similar responses to Glu. This suggests that the nature of GTF may differ from RVLM and DM. 4. The above results suggest that the Glu-induced pressor responses from LC, GTF, DM and especially RVLM, are primarily mediated through AMPA receptors. The Glu-induced depressor responses from CVLM may not be predominantly mediated by either AMPA or NMDA receptors. 5. In both baroreceptor-intact and -denervated cats stimulation of the pressor areas often produced an increase of VNA and a decrease of RNA, while in the depressor CVLM decreased both VNA and RNA. The VNA, but not RNA were positively correlated with the pressor responses, while both VNA and RNA were positively correlated with the depressor responses. This may suggest that neurons of the sympathetic vertebral and renal nerves are topographically organized in the brain.

2-Amino-5-phosphonovalerate↗
PubMed1997

Orthopaedic ice-skating injuries in a regional hospital in Hong Kong.

Ice-skating is a popular sport in Hong Kong. Since the opening of our hospital, we have observed a special pattern of injury related to ice-skating. Individuals have had a wide range of injuries including fractures and deep tissue lacerations, many of which have needed operative intervention. Public awareness of the risks remains low. The pattern and mechanisms of injury, management modalities, and contributing factors to the injuries are discussed. Preventive measures and socioeconomic implications are also discussed.

Journal Article↗
PubMed1997

Balanced fluid exchange by volume homeostatic fluid-fluid exchanger--a new solution to postvitrectomy vitreous hemorrhage.

We introduce a new device and a new technique that facilitate the clearance of postvitrectomy vitreous hemorrhage. We have developed a volume homeostatic fluid-fluid exchanger--Chen's Infusion/Aspiration (Chen's I/A) device. Due to reciprocal synchronized hydraulic action, Chen's I/A provides simultaneous infusion and aspiration of fluid of equal amounts. Therefore, it can be used to perform vitreous cavity lavage through smaller caliber needles and at the same time maintain a constant intraocular pressure. This improved vitreous cavity lavage technique is named Balanced Fluid Exchange. Performing Balanced Fluid Exchange with Chen's I/A can reduce trauma to the eyeball and decrease complications resulting from unstable intraocular pressure. Thus, it increases both the intra-operative and post-operative clearance rates of postvitrectomy vitreous hemorrhage, and is a promising method for the management of postvitrectomy vitreous hemorrhage.

Hemostatic Techniques↗