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Biomedical subjects

C L Ho

Publications and source records attributed to C L Ho.

At least 37 records · Page 2Linked to original sources
PubMed2000

Lymphoma of bone with initial presentation as a calvarial mass.

A 21-year-old man was examined for a right frontal skull mass that had been present for 4 months. Excision biopsy of the mass revealed diffuse large B-cell lymphoma. Subsequent studies showed right preauricular lymphadenopathy but no systemic involvement. The patient was treated with six courses of CHOP (cyclophosphamide, adriamycin, vincristine, and prednisolone) with adjuvant whole brain irradiation and achieved a complete remission.

Adult↗
PubMed2000

Acute respiratory distress syndrome following intrathecal methotrexate administration: a case report and review of literature.

Acute Respiratory distress syndrome (ARDS) is a rare complication following intrathecal (IT) injection of methotrexate (MTX) in adult acute lymphoblastic leukemia (ALL) patients. A 19-year-old man with ALL developed strikingly acute respiratory failure during central nervous system (CNS) prophylaxis with IT MTX administration and cranial irradiation. Histopathologic study of the lungs revealed a pattern of diffuse alveolar damage with interstitial cellular infiltration. His symptoms were relieved soon following treatment with corticosteroids and the pulmonary infiltrates resolved gradually. Pulmonary symptoms did not recur as he was continuously treated with oral corticosteroids.

Adult↗
PubMed2000

Cerebral dural sinus thrombosis in acute lymphoblastic leukemia with early diagnosis by fast fluid-attenuated inversion recovery (FLAIR) MR image: a case report and review of the literature.

Cerebral dural sinus thrombosis (CDST) is a very rare complication of acute lymphoblastic leukemia (ALL) in adult patients. A 23-year-old man with ALL developed dizziness, headache, diplopia, limb weakness, and a sensation of fullness in his head after his second induction chemotherapy with doxorubicin, prednisolone, and vincristine. Examinations of the peripheral blood, bone marrow, and cerebrospinal fluid showed no recurrent leukemic cells. Magnetic resonance (MR) imaging of the brain disclosed unexpected CDST at the left transverse sinus, which was seen only on the fast fluid-attenuated inversion recovery (FLAIR) sequence. His symptoms were relieved soon after treatment with heparin. MR imaging with FLAIR performed a second time 7 days later showed complete disappearance of the thrombosis. The patient was treated continuously with oral anticoagulant therapy and the symptoms did not recur. CDST can be diagnosed in its early phase by MR studies with FLAIR images. Anticoagulant therapy can be administered safely without precipitating the occurrence of infarction hemorrhage at such an early stage of CDST.

Adolescent↗
PubMed2000

Rapid movement of axonal neurofilaments interrupted by prolonged pauses.

Axonal cytoskeletal and cytosolic proteins are synthesized in the neuronal cell body and transported along axons by slow axonal transport, but attempts to observe this movement directly in living cells have yielded conflicting results. Here we report the direct observation of the axonal transport of neurofilament protein tagged with green fluorescent protein in cultured nerve cells. Live-cell imaging of naturally occurring gaps in the axonal neurofilament array reveals rapid, intermittent and highly asynchronous movement of fluorescent neurofilaments. The movement is bidirectional, but predominantly anterograde. Our data indicate that the slow rate of slow axonal transport may be the result of rapid movements interrupted by prolonged pauses.

Animals↗
PubMed2000

Elucidation of the solution structure of cardiotoxin analogue V from the Taiwan cobra (Naja naja atra)--identification of structural features important for the lethal action of snake venom cardiotoxins.

The aim of the present study is to understand the structural features responsible for the lethal activity of snake venom cardiotoxins. Comparison of the lethal potency of the five cardiotoxin isoforms isolated from the venom of Taiwan cobra (Naja naja atra) reveals that the lethal potency of CTX I and CTX V are about twice of that exhibited by CTX II, CTX III, and CTX IV. In the present study, the solution structure of CTX V has been determined at high resolution using multidimensional proton NMR spectroscopy and dynamical simulated annealing techniques. Comparison of the high resolution solution structures of CTX V with that of CTX IV reveals that the secondary structural elements in both the toxin isoforms consist of a triple and double-stranded antiparallel beta-sheet domains. Critical examination of the three-dimensional structure of CTX V shows that the residues at the tip of Loop III form a distinct "finger-shaped" projection comprising of nonpolar residues. The occurrence of the nonpolar "finger-shaped" projection leads to the formation of a prominent cleft between the residues located at the tip of Loops II and III. Interestingly, the occurrence of a backbone hydrogen bonding (Val27CO to Leu48NH) in CTX IV is found to distort the "finger-shaped" projection and consequently diminish the cleft formation at the tip of Loops II and III. Comparison of the solution structures and lethal potencies of other cardiotoxin isoforms isolated from the Taiwan cobra (Naja naja atra) venom shows that a strong correlation exists between the lethal potency and occurrence of the nonpolar "finger-shaped" projection at the tip of Loop III. Critical analysis of the structures of the various CTX isoforms from the Taiwan cobra suggest that the degree of exposure of the cationic charge (to the solvent) contributed by the invariant lysine residue at position 44 on the convex side of the CTX molecules could be another crucial factor governing their lethal potency.

Amino Acid Sequence↗
PubMed2000

Protective and defensive airway reflexes evoked by nasal exposure to wood smoke in anesthetized rats.

We investigated the airway responses evoked by nasal wood smoke in anesthetized Sprague-Dawley rats. Wood smoke (5 ml, 1.4 ml/s) was delivered into an isolated nasal cavity while animals breathed spontaneously. In study 1, nasal wood smoke triggered either an apneic response (n = 26) or a sniff-like response (n = 16) within 1 s after smoke exposure in 42 normal rats. Both airway responses were abolished by trigeminal nerve denervation and by nasal application of a local anesthetic or a hydroxyl radical scavenger, but they were not significantly affected by removal of smoke particulates or nasal application of a saline vehicle. In study 2, nasal wood smoke only triggered a mild apneic response in two rats neonatally treated with capsaicin and had no effect on breathing in the other six; the treatment is known to chronically ablate C fibers and some Adelta fibers. In contrast, nasal wood smoke evoked an apneic response in six rats neonatally treated with the vehicle of capsaicin and elicited a sniff-like response in the other two. These results suggest that the apneic and sniff-like responses evoked by nasal wood smoke result from the stimulation of trigeminal nasal C-fiber and Adelta-fiber afferents by the gas-phase smoke and that hydroxyl radical is the triggering chemical factor.

Animals↗
PubMed2000

Acute lymphoblastic leukemia in young adults: two chemotherapeutic protocols for the treatment of 46 patients.

BACKGROUND: Acute lymphoblastic leukemia (ALL) in adults has a very poor prognosis. Many chemotherapeutic protocols have been designed to try to improve treatment results for adult ALL. Two chemotherapeutic protocols were used to treat young adult ALL patients in our institute and treatment results are reported. METHODS: From 1984 through 1997, 46 young adult patients with ALL were treated. There were 43 males and three females. Their ages ranged from 16 to 38 years, with a median of 24 years. Thirty-two patients (group A) received a four-week conventional induction regimen with daunomycin, vincristine, prednisolone, and L-asparaginase, followed by prophylaxis of the central nervous system (CNS) with intrathecal methotrexate and cranial irradiation, as well as maintenance therapy with oral 6-mercaptopurine and methotrexate. Fourteen patients (group B) received the modified protocol of the German multicenter trial for adult ALL (GMALL) with a two-phase induction regimen, CNS prophylaxis and maintenance therapy. RESULTS: In group A, 25 of 32 patients achieved complete remission (CR), three obtained partial remission and four died of treatment-related complications during induction therapy. The median duration of remission (DR) was 12 months (range, 3-39 months) and the median overall survival time (OST) was 13 months (range, 0.5-50 months). Of the 25 patients who achieved CR, 21 relapsed and died. In group B, 11 of 14 patients obtained CR and three died of leukopenia-related infectious complications during induction. The median DR was 12 months (range, 8-37 months) and the median OST was 15 months (range, 0.5-39 months). During follow-up, 10 of 11 patients relapsed from ALL and died. Only one patient who received allogeneic bone marrow transplantation first CR is still alive. No statistical differences between the two groups were noted in terms of CR rate, DR (p = 0.87) and OST (p = 0.34). However, the the GMALL protocol had during the significantly more hematologic toxicity during induction therapy. CONCLUSIONS: Our results suggest that young adult ALL is a disease with a very poor prognosis and conventional chemotherapy is not adequate for its treatment. The notion that GMALL protocol is better than conventional therapy in the treatment of adult ALL cannot be justified by our data.

Adolescent↗
PubMed2000

Cyclosporine-induced encephalopathy in a patient with relapsed acute myeloid leukemia treated with unrelated allogeneic bone marrow transplantation.

Cyclosporine (CSP) is the most frequently used immunosuppressive agent for prevention of graft versus host disease (GVHD) in allogeneic bone marrow transplantation (BMT). Some adverse effects such as hepatic and renal toxicity have been frequently encountered, but central nervous system (CNS) toxicity caused by CSP is rare. We report an adult male patient with acute myeloid leukemia who developed CSP-induced encephalopathy under treatment for allogeneic BMT from an unrelated donor. Methotrexate and CSP were used for GVHD prophylaxis. Leukocyte and platelet engraftment were successfully achieved on days 21 and 24 after BMT, respectively. Abrupt onset of mental confusion and disorientation occurred on day 25, followed by a generalized tonic clonic seizure and consciousness disturbance. The whole blood CSP level was 160.65 ng/mL. Magnetic resonance (MR) imaging revealed high signal intensities in the bilateral occipital lobes with predominant involvement of the cortical areas. The patient recovered from the CNS toxicity, but with slight memory impairment, 6 days after CSP was discontinued. When patients receiving CSP treatment for allogeneic BMT develop mental confusion, consciousness disturbance, or seizure, CSP-induced CNS toxicity should be taken into consideration.

Adult↗
PubMed2000

Macular translocation--an innovative treatment for macular degenerative diseases.

BACKGROUND: Age-related macular degeneration with subfoveal choroidal neovascularization (CNV) is difficult to handle with any treatment modality so far. Macular translocation is an innovative surgical approach to this disease. METHODS: The "full" macular translocation comprises phacoemulsification, complete vitrectomy, artificial retinal detachment, 360 degrees retinotomy, removal of the CNV, translocation of the neurosensory retina, and endotamponade with silicone oil. The "limited" macular translocation is accomplished by partial retinal detachment and scleral imbrication. The CNV can be removed during the operation or ablated by a laser postoperatively. RESULTS: Full macular translocation was performed on 3 eyes, and upward macular displacement was achieved from 10 to 45 degrees. Limited macular translocation was performed on 2 eyes, and downward macular displacement was achieved from 350 to 900 microns. One eye had visual improvement, 2 eyes remained stationary, and another 2 eyes had worse visual acuity postoperatively. No proliferative vitreoretinopathy occurred in any of these eyes. CONCLUSION: Macular translocation can relocate the macula to a healthy adjacent retinal pigment epithelium-choroid bed and is a promising surgical treatment for macular degenerative disorders. Further trials are mandatory to evaluate its benefits.

Adult↗
PubMed2000

Perfluorodecalin condensation on posterior surface of lens capsule and corneal endothelium during vitrectomy.

BACKGROUND: High-density vitreous substitutes, including perfluorodecalin, are widely used in current vitreoretinal surgery. We report 4 cases of perfluorodecalin condensation on the posterior capsule of the lens or corneal endothelium during vitrectomy. To the best of our knowledge, no such phenomenon has ever been reported. METHODS: This study consisted of 4 patients with retinal detachment and large retinal tears. All patients were men. All of the patients underwent pars plana vitrectomy, perfluorodecalin injection, endolaser retinopexy and air-fluid exchange. Two patients received additional surgery for scleral buckling. RESULTS: Perfluorodecalin condensation was observed on the posterior surface of the lens capsule in one phakic patient and on the endothelium in three aphakic patients during vitrectomy. The condensation obscured the image of the fundus and made air-fluid exchange difficult. The condensation could be dissipated by first removing the perfluorodecalin as completely as possible, and then by lowering the intraocular pressure below the vapor pressure of perfluorodecalin. CONCLUSIONS: Perfluorodecalin condensation may occur when perfluorodecalin is not properly used. To avoid forming condensation, high-density vitreous substitutes should never be injected into eyes that are completely air-filled, prolonged air-fluid exchanges should be avoided, and the intraocular pressure should always be kept at a higher level during air-fluid exchange.

Adult↗
PubMed1999

Plastidic pathway of serine biosynthesis. Molecular cloning and expression of 3-phosphoserine phosphatase from Arabidopsis thaliana.

In plants, Ser is biosynthesized by two different pathways: a photorespiratory pathway via Gly and a plastidic pathway via the phosphorylated metabolites from 3-phosphoglycerate. In contrast to the better characterization of the photorespiratory pathway at a molecular level, the molecular regulation and significance of the plastidic pathway are not yet well understood. An Arabidopsis thaliana cDNA encoding 3-phosphoserine phosphatase, the enzyme that is responsible for the conversion of 3-phosphoserine to Ser in the final step of the plastidic pathway of Ser biosynthesis, was cloned by functional complementation of an Escherichia coli serB- mutant. The 1.1-kilobase pair full-length cDNA, encoding 295 amino acids in its open reading frame, contains a putative organelle targeting presequence. Chloroplastic targeting has been demonstrated by particle gun bombardment using an N-terminal 60-amino acid green fluorescence protein fusion protein. Southern hybridization suggested the existence of a single-copy gene that mapped to chromosome 1. 3-Phosphoserine phosphatase enzyme activity was detected in vitro in the overexpressed protein in E. coli. Northern analysis revealed preferential gene expression in leaf and root tissues of light-grown plants with an approximately 1.5-fold abundance in the root compared with the leaf tissues. This indicates the possible role of the plastidic pathway in supplying Ser to non-photosynthetic tissues, in contrast to the function of the photorespiratory pathway in photosynthetic tissues. This work completes the molecular cloning and characterization of the three genes involved in the plastidic pathway of Ser biosynthesis in higher plants.

Amino Acid Sequence↗
PubMed1999

Regulation of serine biosynthesis in Arabidopsis. Crucial role of plastidic 3-phosphoglycerate dehydrogenase in non-photosynthetic tissues.

In plants, Ser is synthesized through a couple of pathways. 3-Phosphoglycerate dehydrogenase (PGDH), the first enzyme that is involved in the phosphorylated pathway of Ser biosynthesis, is responsible for the oxidation of 3-phosphoglycerate to phosphohydroxypyruvate. Here we report the first molecular cloning and characterization of PGDH from Arabidopsis thaliana. Sequence analysis of cDNA and a genomic clone revealed that the PGDH gene is composed of three exons, encoding a 623-amino acid polypeptide (66, 453 Da). The deduced protein, containing three of the most conserved regions in the NAD-dependent 2-hydroxyacid dehydrogenase family, has 38-39% identity to its animal and bacterial counterparts. The presence of an N-terminal signal sequence for translocation into plastids was confirmed by particle-gun bombardment experiments using green fluorescence protein as a reporter protein for subcellular localization. Southern hybridization analysis and restriction fragment length polymorphism mapping indicated that PGDH is a single-copy gene that is mapped to the upper arm of chromosome 1. Northern hybridization analysis indicated preferential expression of PGDH mRNA in root tissues of light-grown plants, suggesting that the phosphorylated pathway of Ser biosynthesis plays an important role in supplying Ser to non-photosynthetic tissues. The recombinant enzyme overproduced in Escherichia coli displayed hyperbolic kinetics with respect to 3-phosphoglycerate and NAD+.

Amino Acid Sequence↗
PubMed1999

Mandibular mass as the presenting manifestation of IgM myeloma in a 22-year-old man.

We report here the youngest known IgM myeloma patient to have presented with a mandibular mass. A 22-year-old Chinese man sought medical attention due to a mass over his right mandible that had been growing progressively for 6 months. A solitary osteolytic lesion in the right mandible was identified radiologically. Incisional biopsy revealed the presence of plasma cells of monoclonal origin, as evidenced by the exclusively positive staining of the kappa light chain. The diagnosis of multiple myeloma with mandibular involvement was confirmed by bone marrow examination. Further tests, including immunoglobulin electrophoresis and assay of the serum levels of kappa and lambda light chains, demonstrated that his myeloma was of the IgM, kappa subtype. The patient achieved a nonsustained partial response to six courses of melphalan and prednisolone therapy and palliative radiotherapy.

Adult↗
PubMed1999

Adrenal insufficiency caused by primary aggressive non-Hodgkin's lymphoma of bilateral adrenal glands: report of a case and literature review.

A 64-year-old woman was hospitalized because of poor general condition, gastrointestinal upset, unexplained fever, electrolyte imbalances, and an incidental finding of bilateral huge adrenal masses on computerized tomography (CT) of the abdomen. Non-Hodgkin's lymphoma (NHL) of B-cell origin was proven by ultrasound-guided aspiration biopsy of the left adrenal gland. Meanwhile, primary adrenal insufficiency was confirmed by her low serum cortisol level, high ACTH level, and inadequate adrenal response to the rapid ACTH stimulation test. The diagnosis of primary adrenal NHL was supported by detailed physical examinations, bone marrow examination, and such imaging studies as CT scan and sonography. She received three courses of chemotherapy with cyclophosphamide, vincristine, and prednisolone and there was an initial transient response, but she died of sepsis and progression of NHL three and a half months later.

Adrenal Gland Neoplasms↗
PubMed1999

Three toxins with phospholipase activity isolated from the yellow-legged hornet (Vespa verutina) venom.

The yellow-legged hornet, Vespa verutina, is widely distributed in both the mountain area and the suburbs of Taiwan and possesses highly toxic venom (LD50=0.02 microl/g mouse). By gel filtration on Fractogel (TSK HW 50f) followed by cation-exchange chromatography on Mono S column, three toxins designated as verutoxin 1, 2a and 2b (VT-1, VT-2a and VT-2b) were isolated from the venom. The toxin VT-1 had a molecular mass of 34,982 Da and an LD50 value of 3.61 microg/g mouse. Toxin VT-2a and 2b were more basic and more toxic than VT-1. VT-2a and 2b were isotoxins with molecular masses differing in only 14 Da (33,360 and 33,374 Da, respectively) and had a similar toxicity in mice (LD50=0.87 microg/g mouse). All three toxins were capable of catalyzing the hydrolysis of emulsified phospholipids and lysophosphatide, but not sphingomyelin. Analysis of the hydrolyzed products (fatty acid and lyso-compound) by a liquid chromatography/mass spectrometer revealed that the toxins liberates fatty acid mainly from the 1-position of the synthetic phospholipid. This result indicates that verutoxins possess phospholipase A1 activity. Toxin VT-1 showed higher phospholipase activity than VT-2a and 2b. However, the latter toxins exhibited much higher direct hemolytic activity toward the mouse red blood cells. Vespid phospholipases are known as one of the three major venom allergens in many species of wasps. Our studies indicate that vespid phospholipases A1, in addition to acting as allergens, possess direct toxic actions that may also cause death in animals. Toxin VT-2a and 2b which possess potent hemolytic activity and high lethality in mice may act as the lethal factor of V. verutina venom.

Amino Acid Sequence↗
PubMed1999

Excimer laser phototherapeutic keratectomy for recurrent corneal erosions.

The purpose of this paper was to review the Singapore National Eye Centre's (SNEC) experience with excimer laser phototherapeutic keratectomy (PTK) for treating recurrent corneal erosions (RCE). Thirty-five eyes of 32 patients who had PTK between 1992 and 1997 in SNEC were studied retrospectively. There was a history of previous ocular trauma in 15 eyes. Sixteen eyes had anterior corneal dystrophy. All had received conventional therapy without improvement in symptoms. The mean duration of symptoms prior to PTK was 19 months (range 1 to 71 months). PTK was performed with one of two 193 nm excimer lasers (Summit UV200LA, Summit Technology, Waltham, USA or Visx 20/20B, Visx Corp, Santa Clara, USA). An average of 30 laser pulses were delivered to Bowman's membrane after debridement of the corneal epithelium. The mean follow-up time was 12 months (range 0 to 56 months). Among those with adequate length of follow-up, 26/27 eyes (96%) were symptom-free for 3 months, 19/22 eyes (86%) were symptom-free for 6 months and 9/13 eyes (69%) were symptom-free for 1 year. Three eyes had repeat PTK. Mild corneal haze was seen in 3 eyes. No visually threatening complications were encountered. PTK is a safe and effective procedure for RCE refractory to conventional treatment.

Adult↗
PubMed1998

Comparison of the immunogenicity of wasp venom peptides with or without carbohydrate moieties.

Three synthetic vespulakinin analogues either with or without carbohydrate moieties and mastoparan B isolated from Vespa basalis venom were investigated for their immunogenic activity and solution conformation. Mice immunized with these wasp venom peptides, with the exception of (Gal alpha)Thr3, (Gal alpha)Thr4-vespulakinin 1, showed positive antibody responses. However, the response elicited by mastoparan B was much higher than those induced by vespulakinin analogues. The class of antibody induced by these peptides was identified as an IgG1 isotype with kappa-light chain, suggesting stimulation of a T-cell-dependent immune response by these peptides. According to the circular dichroism spectra of these peptides, the structures of the vespulakinin analogues in solution were largely unordered, while mastoparan B exhibited a conformation rich in alpha-helices. The presence of carbohydrate moieties and the rather random structure in vespulakinins may interfere with T-cell recognition of the peptides, leading to lower immune responses.

Allergens↗