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T K Ho

Publications and source records attributed to T K Ho.

15 recordsLinked to original sources
PubMed2006

Increased angiogenic response but deficient arteriolization and abnormal microvessel ultrastructure in critical leg ischaemia.

BACKGROUND: Ischaemia is known to induce angiogenesis, but the effects of critical leg ischaemia (CLI) on angiogenesis remain unclear. The aim of this study was to examine the physiological angiogenic response in CLI by investigating the extent of neovascularization, characterizing microvessel subtypes and determining the microvessel ultrastructure. METHODS: Gastrocnemius muscles were biopsied from 12 patients with CLI and 12 without leg ischaemia. Microvessels were evaluated immunohistochemically using three endothelial markers (anti-CD31, anti-CD34 and PAL-E) and anti-alpha smooth muscle actin (SMA) as a mural cell marker to label arterioles. Ki67 was used to demonstrate active cell proliferation. Further microvessel ultrastructural characteristics were determined by transmission electron microscopy. RESULTS: The CLI group had significantly higher microvessel density and microvessel : muscle fibre ratio for all endothelial subtypes examined (P < 0.001). PAL-E staining demonstrated the highest increase: 4.7 times higher in CLI muscle. There was no significant difference in alphaSMA-positive microvessel density (P = 0.118) or microvessel: muscle fibre ratio (P = 0.214). Ki67 staining showed no active cell proliferation. Transmission electron microscopy showed CLI microvessels had abnormal morphology, mainly a thick basement membrane. CONCLUSION: A physiological angiogenic response was found in CLI, but the microvessels had an abnormal ultrastructure. A lack of active cell proliferation suggests that the angiogenic response may have been exhausted.

Aged↗
PubMed1996

Prevalence of associated infections in community-acquired spontaneous bacterial peritonitis.

OBJECTIVES: The frequency with which other infections occur in association with spontaneous bacterial peritonitis is not known, but has implications for both pathogenesis and management. Spontaneous bacterial peritonitis that occurs in hospitalized patients is mainly a nosocomial infection, the study of which must take into account multiple confounding factors. We conducted a prospective study to compare the clinical features and the frequency of associated infections in patients with community-acquired spontaneous bacterial peritonitis to those of cirrhotic patients with ascites but without spontaneous bacterial peritonitis. Previous studies of spontaneous bacterial peritonitis have not found an infection consistently present at some other site, but those studies did not separate community-acquired from hospital-acquired spontaneous bacterial peritonitis. METHODS: Over a 5-yr study period, 176 cirrhotic patients with ascites were enrolled and were followed. There were 68 patients who had 83 admissions with spontaneous bacterial peritonitis and 108 patients with 124 admissions without spontaneous bacterial peritonitis. Of the 68 patients with spontaneous bacterial peritonitis, 56 had single episodes of peritonitis and 12 had 27 episodes of recurrent bacterial peritonitis. All episodes of spontaneous bacterial peritonitis were diagnosed within 24 h of admission. All subjects had cultures of ascitic fluid, blood, and urine. RESULTS: Patients with spontaneous bacterial peritonitis were more often symptomatic than the nonspontaneous bacterial peritonitis patients. Ascites cultures were positive in 63 (76%) episodes of spontaneous bacterial peritonitis. The frequency of bacteremia in the spontaneous bacterial peritonitis group was significantly higher than that of the nonspontaneous bacterial peritonitis (56.6% vs. 4.8%, p < 0.0001). Bacteriuria occurred in 51 episodes of spontaneous bacterial peritonitis compared with only nine in nonspontaneous bacterial peritonitis patients (61.4% vs. 7.3%, p < 0.0001). Bacteriuria was observed even more often in recurrent bacterial peritonitis patients than in single episode bacterial peritonitis patients (77.8% vs. 53.6%, p < 0.0001). Most patients with bacteriuria had no urinary tract symptoms. There was no significant difference between the frequency of pneumonia in spontaneous bacterial peritonitis patients compared with nonspontaneous bacterial peritonitis patients (8.4% vs. 10.5%, p = 0.17). CONCLUSIONS: Asymptomatic bacteriuria occurs often in association with community-acquired spontaneous bacterial peritonitis.

Bacteremia↗
PubMed1995

Posterior cruciate avulsion fracture associated with a large inverted medial tibial osteochondral fragment.

A case of traumatic avulsion fracture of the posterior cruciate ligament in association with a large osteochondral fracture of the medial tibial condyle is described. The osteochondral fragment was inverted 180 degrees. Many associated injuries of the posterior cruciate ligament have been described. This unusual combination of fractures to the best of our knowledge has not been reported before. The mechanism of injury and its clinical implications are discussed.

Adult↗
PubMed1994

Laser iridotomies in Asian eyes.

Argon laser iridotomy and Nd:YAG (Neodymium: Yttrium-Aluminium-Garnet) iridotomy are the two established techniques of laser iridotomies. However, in the thicker and more heavily pigmented Asian irides, they are associated with higher complication and failure rates. A third iridotomy technique that is recently described is the sequential argon-YAG laser iridotomy. Here, both the argon and Nd:YAG laser are used serially at the same sitting to achieve a patent iridotomy. By using the argon to make the initial bore and the Nd:YAG laser to complete the perforation, the technique is able to effectively combine most of the advantages of both lasers whilst avoiding their disadvantages. It is possibly the ideal iridotomy technique to use in the Asian irides.

Argon↗
PubMed1991

Palladium 103 ophthalmic plaque radiotherapy.

We compared the ocular radiation distribution of palladium 103 (103Pd) vs iodine 125 (125I) ophthalmic plaques sewn to 12 human donor eyes. We then performed preoperative comparative simulations on the first seven patients to be treated with palladium 103 plaque therapy for choroidal melanoma. The in vitro experiment involved palladium 103 seeds placed into a Silastic seed holder, which was affixed into standard 14-mm gold eye plaques. Then the plaques were sewn onto 12 human donor eyes so as to approximate either the nasal (six eyes) or temporal (six eyes) equator. Three sets of two thermoluminescent dosimeters were used to quantify the amount of radiation delivered by the episcleral plaques. Thermoluminescent dosimeters were sewn to the sclera in three locations: on the center of the cornea, on the sclera beneath the macula, and at the equator in a position opposite the plaque. This experiment was then repeated with iodine 125 seeds and thermoluminescent dosimeters. After the plaques were adjusted to equalize their activity (plaque strength), the palladium 103 plaques were found to deliver less radiation to the three target points. Comparative clinical dosimetry also reflected this difference. Preoperative simulations comparing equal doses to the tumors' apex revealed that the palladium 103 ophthalmic plaques delivered more radiation to the tumor and less radiation to most normal ocular structures.

Brachytherapy↗
PubMed1990

Intraocular radiation blocking.

Iodine-based liquid radiographic contrast agents were placed in normal and tumor-bearing (Greene strain) rabbit eyes to evaluate their ability to block iodine-125 radiation. This experiment required the procedures of tumor implantation, vitrectomy, air-fluid exchange, and 125I plaque and thermoluminescent dosimetry (TLD) chip implantation. The authors quantified the amount of radiation attenuation provided by intraocularly placed contrast agents with in vivo dosimetry. After intraocular insertion of a blocking agent or sham blocker (saline) insertion, episcleral 125I plaques were placed across the eye from episcleral TLD dosimeters. This showed that radiation attenuation occurred after blocker insertion compared with the saline controls. Then computed tomographic imaging techniques were used to describe the relatively rapid transit time of the aqueous-based iohexol compared with the slow transit time of the oil-like iophendylate. Lastly, seven nontumor-bearing eyes were primarily examined for blocking agent-related ocular toxicity. Although it was noted that iophendylate induced intraocular inflammation and retinal degeneration, all iohexol-treated eyes were similar to the control eyes at 7 and 31 days of follow-up. Although our study suggests that intraocular radiopaque materials can be used to shield normal ocular structures during 125I plaque irradiation, a mechanism to keep these materials from exiting the eye must be devised before clinical application.

Animals↗
PubMed1989

Thermoradiotherapy of choroidal melanoma. Clinical experience.

Thermoradiotherapy (TRT) was used to treat 18 patients with choroidal melanoma. Techniques and clinical observations using a plaque-type device capable of delivering microwave hyperthermia to intraocular tumors are described. Iodine-125 plaque irradiation (48-88 Gy to apex), together with microwave hyperthermia (46 degrees-52.5 degrees C to base), were given to patients during one brachytherapy session. Since October 1985, 15 medium and 3 large-sized tumors were treated. Clinical observations include partial clearing of six vitreous opacities as well as three retinal detachments noted before treatment. Objective measurements of improved visual acuity were noted in seven of the nine cases. All tumors responded to treatment, but one tumor had regrowth and the eye was enucleated. These data suggest that a microwave plaque can be used to deliver hyperthermia to human choroidal melanomas. Within the range of the follow-up period, no side effects that might preclude the use of this hyperthermia system for choroidal melanoma treatment were noted.

Choroid Neoplasms↗
PubMed1984

Isolation of Ca2+-tolerant myocytes from adult rat heart.

A procedure for the isolation of myocytes from adult rat hearts is described. It is based on successive treatments with Ca2+-free medium, disaggregating enzymes (collagenase and hyaluronidase) and mechanical agitation. Several recent isolation methods were compared and their best features were combined, together with some original modifications. A good yield of high purity myocytes with excellent morphological and functional integrity was obtained. The cells are tolerant to physiological concentrations of Ca2+. Cellular levels of ATP, Na+, and K+ are close to those in intact hearts and glucose oxidation rates and succinate exclusion are also close to normal. These characteristics are maintained for periods over 1 h.

Adenosine Triphosphate↗
PubMed1978

Opiate properties of SKF 525A.

SKF 525A, a classical inhibitor of microsomal drug-metabolizing enzymes, is structurally similar to the diphenylpropylamine analgesics, and certain reported effects in animals resemble those produced by opiate drugs. In an opiate radioreceptor assay, SKF 525A was 50 times less potent than methadone in the absence of sodium and 10 times less potent in the prescence of sodium. The nature of the sodium effect indicates SKF 525A to have less opiate agonist character than does methadone. In mice, 2 mg of SKF 525A given intraperitoneally induced less profound analgesia on a hot plate (44 degrees C) than did 0.1 mg of methadone. Analgesia by SKF 525A was prevented by pretreatment of the mice with naloxone. In rats, 50 microgram of SKF 525A given intracerebroventricularly was analgesic.

Analgesia↗