Biomedical subjects

S T Chen

Publications and source records attributed to S T Chen.

At least 109 records · Page 6Linked to original sources

PubMed1996

Magnetic resonance images of Tolosa-Hunt syndrome before and after steroid therapy.

Tolosa-Hunt syndrome (THS) is characterized by painful ophthalmoplegia due to idiopathic granulomatous inflammation of the cavernous sinus. Steroid therapy dramatically reverses the clinical signs and symptoms of THS. We report a typical case of THS, in which MRI showed a mass lesion in the right cavernous sinus with intermediate signal intensity on T1-weighted images, hypointensity on T2-weighted images and positive gadolinium enhancement. This 24-year-old man had three episodes of painful opthalmoplegia in a period of 9 months. The side of the involved cavernous sinus was different in the first and the second episodes of THS. The symptoms lasted for 1 month and the patient recovered spontaneously from these two episodes. In the third episode, the right pupil was also involved and the light reflex was lost. After steroid therapy, the ocular symptoms improved rapidly within 48 hours and the mass lesion in the right cavernous sinus on MRI was markedly diminished by the 7th day of treatment.

Adult↗

PubMed1996

Distribution of beta-amyloid precursor and B-cell lymphoma protooncogene proteins in the rat retina after optic nerve transection or vascular lesion.

The expression of beta-amyloid precursor protein (APP) and B-cell lymphoma protooncogene protein (Bcl-2) in retinal cells in the rat was studied using immunocytochemistry at different times after intraorbital optic nerve transection or vascular lesion. Three hours to one month after transection of the optic nerve, a significant increase in APP and Bcl-2 immunostaining was observed in retinal Müller glia but not in retinal neurons. In contrast, injury to blood vessels that supply the eye without cutting the optic nerve resulted in a complete loss of APP and Bcl-2 immunostaining in Müller cells and an increase in immunoreactivity in distinct populations of retinal neurons. The overall pattern of APP immunostaining in Müller cells and neurons was essentially the same as that of Bcl-2 under identical experimental conditions. These results suggest that the expression of APP and Bcl-2 in retinal cells is dependent on the nature and severity of injury, and that rapid and common mechanisms are involved in regulating the expression of these molecules.

Amyloid beta-Peptides↗

PubMed1996

Juvenile-onset of Dejerine-Sottas disease in a Taiwanese woman.

Dejerine-Sottas disease is an uncommon hereditary neuropathy which has not been reported in Taiwan. We describe a 57-year-old woman who had slowly progressive weakness in her four limbs since adolescence. None of her close relatives had the disease and no consanguinity was noted. Neurologic examination showed severe weakness and vibratory sensation loss in the four limbs. The tendon reflexes were generally absent. Electrophysiologic studies suggested a systemic myelinopathic process. Light and electron microscopy of the sural nerve biopsy specimens revealed many onion-bulb shapes formed by the Schwann cell processes or basement membranes without any evidence of myelin sheaths around the axons, which are characteristic features of Dejerine-Sottas disease.

Age of Onset↗

PubMed1996

Vocal cord paralysis as an initial sign of multiple system atrophy in the central nervous system.

Multiple system atrophy (MSA) of the central nervous system has been recognized as a rare cause of stridor secondary to vocal cord paralysis. This respiratory problem usually occurs in the later stages of the disease. We report the case of a 53-year-old man who presented with bilateral vocal cord paralysis accompanied by stridor and sleep apnea, which were relieved by a tracheostomy. Two years after the onset of stridor, he developed extrapyramidal and cerebellar signs combined with severe autonomic failure. Magnetic resonance imaging of the brain revealed atrophy of the brainstem and cerebellum. This clinical picture is consistent with the diagnosis of MSA. Vocal cord paralysis preceding any other neurologic and autonomic manifestations has been infrequently described. This case should remind clinicians that MSA should be considered in the differential diagnosis of vocal cord palsy of undetermined origin.

Atrophy↗

PubMed1996

Inhibition of in vitro proliferation of chronic myelogenous leukemia progenitor cells by c-myb antisense oligodeoxynucleotides.

Normal hematopoietic progenitors and acute myelogenous leukemia cells show a differential requirement for the encoded product of c-myb proto-oncogene for proliferation. To determine whether c-myb is also differentially required for the proliferation of hematopoietic progenitors of chronic myelogenous leukemia (CML), mononuclear cells derived from both chronic phase and blast crisis were exposed to c-myb antisense oligodeoxynucleotides and assayed for colony-forming ability. Exposure of CML-BC cells from 12 patients to c-myb antisense oligodeoxynucleotides resulted in significant (p<001) inhibition of leukemia colony formation (average inhibition 63%) and was accompanied by down-regulation of c-myb expression. Colonies derived from CML chronic phase progenitors were virtually unaffected in 10 cases, but down-regulation of c-myb expression was not detected. However, in studies conducted with CD34+ leukemia cells, a subset highly enriched for hematopoietic progenitors, colony formation was inhibited at both disease stages, whereas CFU-GM colony formation derived from normal CD34+ cells was not affected by exposure to c-myb antisense oligodeoxynucleotides. These data suggest that CML chronic phase and blast crisis progenitors are both sensitive to the inhibitory effects of c-myb antisense oligomers, and that the lack of inhibition in partially purified CML-chronic phase progenitors is probably due to inefficient penetration of oligodeoxynucleotides into the clonogenic cells. The preferential effect of c-myb antisense oligodeoxynucleotides on colonies arising from the compartment that includes CML-CD34+ progenitors likely reflects the expansion of a cell population with high proliferative potential and elevated c-myb mRNA levels.

Antigens, CD34↗

PubMed1996

Idiopathic hypereosinophilic syndrome with eosinophilic myositis, peripheral neuropathy and central nervous system involvement.

Idiopathic hypereosinophilic syndrome (HES) is a rare disorder marked by a sustained overproduction of eosinophils and a predilection for damage to multiple organ systems. Its neurologic involvement ranges from the central to the peripheral nervous system, and can be associated with eosinophilic myositis. We report a 68-year-old woman who had eosinophilia, eosinophilic dermatitis and eosinophilic pneumonia. She also suffered from numbness and weakness of the lower limbs. Because of long-lasting (> 6 mo) eosinophilia (> 1.5 x 10(9)/L) in the peripheral blood and the fact that no other underlying causes of eosinophilia and neurologic involvement could be identified, a diagnosis of idiopathic hypereosinophilic syndrome was made. The muscle biopsy showed infiltration of inflammatory cells, including a few eosinophils (Liu's stain). Magnetic resonance images, motor evoked potentials, somatosensory evoked potentials and nerve conduction velocities also showed abnormalities in the central and peripheral nervous systems. The pathogenesis and treatments of HES are discussed in this report.

Central Nervous System Diseases↗

PubMed1996

Connective tissue grafting for primary closure of extraction sockets treated with an osteopromotive membrane technique: surgical technique and clinical results.

This article describes a grafting technique using connective tissue to predictably obtain primary closure of extraction sockets treated with an osteopromotive membrane technique. This technique was used for a total of 24 sites in 22 consecutive patients to regenerate alveolar bone in severely damaged ridges and in conjunction with implants immediately installed into extraction sites. Two sites (8.3%) were complicated by premature membrane exposure that necessitated early removal. In the remaining 22 sites, membranes remained completely covered for a mean period of 23.75 weeks (SD = 8.21 weeks; range = 10 to 38 weeks).

Adult↗

PubMed1995

Increased invasive activity of human hepatocellular carcinoma cells is associated with an overexpression of thyroid hormone beta 1 nuclear receptor and low expression of the anti-metastatic nm23 gene.

To understand the role of thyroid hormone in metastasis, we studied the expression of the anti-metastatic nm23 gene in eight human hepatocellular carcinoma (HCC) cell lines. These cells differentially expressed the anti-metastatic nm23 gene. A low level of nm23 proteins was found to have a high in vitro invasive activity which correlated closely with an overexpression of the thyroid hormone beta 1 nuclear receptor (h-TR beta 1). Concurrent with the down-regulation of h-TR beta 1, the invasive activity of HCC cells was suppressed by the thyroid hormone, 3,3',5-triiodo-L-thyronine (T3). These results indicate that the invasive activity of HCC cells was regulated by T3, suggesting that T3 could be involved in modulating the functions of nm23.

Carcinoma, Hepatocellular↗

PubMed1995

Sequence comparison and computer modelling of cardiotoxins and cobrotoxin isolated from Taiwan cobra.

Six cardiotoxins and one neurotoxin isolated and purified from the Taiwan cobra venom (Naja naja atra) possess distinct pharmacological and biochemical properties despite the existence of a grossly similar tertiary structure among these toxins, i. e., a core consisting of a series of short loops and four disulfide bridges. A systematic structure comparison of these major toxin isoforms was made by the secondary-structure predictions together with computer model-building based on the primary sequences and the established X-ray and NMR structures of one published cardiotoxin isoform and cobrotoxin. It is of interest to find that some defined and subtle differences can be detected upon the superposition of these three-dimensional polypeptide chains, which may reflect the intrinsic differences in the surface hydrophobicity of cardiotoxins and cobrotoxin as revealed by hydropathy profiles of these toxins in one of three major loops. The differences seem to correlate with different inhibitory activities exhibited by cardiotoxins in contrast to the lack of activity by cobrotoxin on protein kinase C (PKC).

Amino Acid Sequence↗

PubMed1995

Physicochemical properties of alkaline serine proteases in alcohol.

The alkaline proteases subtilisin Carlsberg and alcalase possess substantial enzymatic activity even when dissolved in ethanol. The crude enzymes were purified by gel filtration and the main fractions suspended in ethanol to give a translucent suspension. Both the supernatant and the resuspended precipitate after high-speed centrifugation were found to have enzymatic activities. The solubility of subtilisin Carlsberg in anhydrous ethanol was found to be 45.1 micrograms/ml and that of alcalase was 48.1 micrograms/ml by Coomassie blue dye-binding method using bovine serum albumin as a standard. In the presence of water, the solubility of both enzymes increased with water content. The stability of enzymes incubated in ethanol was assayed by their amidase and transesterase activities using Ala-Ala-Pro-Phe-pNA as substrate in phosphate buffer (pH8.2) and Moz-Leu-OBzl as substrate in anhydrous ethanol, respectively. The soluble enzymes have a half-life of about 36 hr and that of suspended enzymes about 50 hr in the amidase activity assay, whereas the same soluble enzymes have a half-life of about several hours and that of suspended enzymes 1 h by the transesterase activity assay. The stability of both enzymes decreased as water concentration increased. The diastereoselectivity of the enzyme-catalyzed hydrolysis of diastereo pairs of tetrapeptide esters, L-Ala-L-Ala-(D- or L-)Pro-L-Phe-OMe and L-Ala-L-Ala-(D- or L-)Ala-L-Phe-OMe, in phosphate is as high as that of the transesterification of these substrates in ethanol. It is concluded that active sites and selectivity of alkaline serine proteases in anhydrous alcohol are probably very similar to those in aqueous solution in spite of the fact that a lower reactivity is usually associated with the enzymes in nonaqueous solvents.

Amino Acid Sequence↗

PubMed1995

Long-term expression of the biologically active growth hormone in genetically modified fibroblasts after implantation into a hypophysectomized rat.

We employed the hypophysectomized rats as an animal model to explore the feasibility of using genetically engineered fibroblast cells for growth hormone gene therapy. An internal ribosome entry site (IRES)-directed bicistronic retroviral vector, PSN, which contained a porcine growth hormone (pGH) cDNA at the first cistron and a Neo(r) gene at the second cistron was used to infect primary rat embryo fibroblast (REF) cells. The infected cells (5 x 10(6) cells/rat) were injected directly into the peritoneum of syngeneic hypophysectomized rats. We demonstrate that the implanted PSN-infected REF cells could secrete biologically active pGH in vivo, leading to significant growth of the tibia at day 15 and day 57 post-implantation. We also treated the PSN-infected REF cells with collagen to form a tissue-like structure. The skin-like discs were grafted underneath the skin on the back of rats and cells were retrieved at different times. Using two criteria, semiquantitative reverse transcription-polymerase chain reaction on the pGH RNA extracted from the explants and G418 resistance conferred from the explanted cells, we demonstrate that pGH was expressed in the implanted fibroblasts up to 70 days. Despite the fact that the total pGH RNA level was reduced in the explants of long-time post-implantation, which was probably due to the reduction of transduced cells retained in the explants, the specific efficiencies of pGH RNA expression from these explants were maintained as high as the primary PSN-infected REF prior implantation. These results suggest that fibroblast cells are capable of expressing the foreign genes persistently in vivo.

3T3 Cells↗

PubMed1995

Conformational studies of a synthetic cyclic decapeptide fragment of rat transforming growth factor-alpha.

The solution conformation of a synthetic cyclic decapeptide [with sequence mimicking the third disulfide loop of rat transforming growth factor-alpha (rTGF-alpha)] in deuterated dimethyl sulfoxide was studied by 2D NMR. The determination of solution structures was based on NOE interproton distances, using a combination of distance geometry and simulated annealing protocols. The convergence of the selected structures was evident from the small atomic pairwise root-mean-square deviation values among them. Good agreement was noted between the experimental and simulated NOESY spectra, thereby reflecting the accuracy of the calculated solution structures. Analysis of the structures indicates that the residues Tyr5 and Arg9 exhibit similar side chain orientation as that in the corresponding disulfide loop of human transforming growth factor-alpha.

Amino Acid Sequence↗

PubMed1995

Recurrent hypertensive intracerebral hemorrhage.

Hypertensive intracerebral hemorrhage has been considered as a one-time event with rare recurrence. This observation is quite different from our experience in Taiwan. We, therefore, conducted a systematic review of our series of consecutive patients with recurrent bleeding. During a 2-year period, we encountered 47 patients with recurrent hypertensive intracerebral hemorrhage from a total of 892 consecutive patients with hypertensive hemorrhage (5.3%). There were 25 men and 22 women with a mean age of 59 +/- 10 (range: 36-78) years at the onset of the first hemorrhage and 62 +/- 9 (range: 39-80) years at the second hemorrhage. The median interval between 2 hemorrhages was 2 years and 4 months (range: 1 month to 8.5 years). All except one recurrent hemorrhages occurred at a site different from the previous one. Of the 38 patients admitted to our hospital for both hemorrhages only 5 were regularly treated with antihypertensive therapy. The outcome for the recurrent bleeding was grave: 26% died and 51% became totally dependent or vegetative. Recurrent hypertensive hemorrhage is not as rare as previously thought; it comprises 5.3% of our patients with hypertensive intracerebral hemorrhage. The recurrent hemorrhage, however, rarely occurs at the same location as the previous one. Uncontrolled hypertension appears to be an important risk factor for the recurrence. Control of blood pressure after the first bleeding should be attempted to prevent recurrent hemorrhage.

Adult↗

PubMed1995

Prognosis of deeply comatose patients on ventilators.

Although the concept of brain death has been widely accepted, the criteria required for making the diagnosis remain controversial. This prospective study was undertaken to examine the reliability of a set of clinical criteria adopted in Taiwan. One hundred and forty deeply comatose patients (101 men, 39 women; mean age 49.5 (SD 17.6) years) requiring ventilation were studied. Seventy three patients met the clinical criteria for brainstem death; all developed cardiac asystole (97% within seven days) despite continued full cardiorespiratory support. Brainstem death was diagnosed in only two of the 21 patients with hypoxic or ischaemic insults. This stresses the rarity of hypoxic or ischaemic encephalopathy as a cause of brainstem death. The results show that if strict attention is paid to preconditions and exclusions, brainstem death can be reliably diagnosed on clinical grounds alone.

Adolescent↗

PubMed1995

POEMS syndrome in Chinese.

POEMS (polyneuropathy, organomegaly, endocrine disturbance, M-protein and skin hyperpigmentation) syndrome occurring in Chinese has been inadequately described. Here we report our experience of 12 Chinese patients with the syndrome. This series is similar to those reported from Japan and from the Western world by the predominance of middle-aged males. Diabetic mellitus, a common feature in POEMS syndrome, was not present in our patients. M-protein of the lambda type was demonstrated in 7 patients by immunoelectrophoresis or by immunofixation electrophoresis. Osteosclerosis in Chinese patients is not as common as in patients reported from Japan or from the Western world; a common radiographic finding in our patients was a compression fracture of the thoraco-lumbar spine with or without sclerotic and lytic lesions. The condition has a grave prognosis; 9 patients die within 4 years after onset of the disease despite various kinds of treatment.

Adult↗

PubMed1995

Acute transverse myelopathy and cutaneous vasculopathy in primary Sjögren's syndrome.

Neurologic complications of primary Sjögren's syndrome (SS) may be under-estimated. Here, we report a patient with primary SS, who developed acute transverse myelopathy (ATM) and skin purpuric lesions simultaneously. In the first episode of myelopathy, the patient's neurologic deficits improved after steroid therapy. However, she died of recurrent myelopathy with systemic complications 4 months later. Review of the English-language literature revealed only 3 cases of primary SS associated with ATM, none of the 3 patients had skin lesions. Anti-Ro(SS-A) antibodies, and ATM in our patient suggests that immune-mediated vasculopathy may play a role in the pathogenesis of acute myelopathy in primary SS.

Acute Disease↗

PubMed1995

Brain abscess as a complication of stroke.

BACKGROUND: Systemic infection is a common complication of stroke. However, brain abscess as a complication of stroke has never been reported. CASE DESCRIPTIONS: We report two patients, one with a hypertensive intracerebral hemorrhage and the other with nonseptic cerebral infarction. In both patients, brain abscess developed at the stroke lesion site after an infectious complication. After surgical aspiration and antibiotic treatment, one patient recovered and the other died. CONCLUSIONS: These two cases demonstrate that brain abscess may occur in a previous hemorrhage or infarction area as a complication of systemic infection. Recognition of the risk is important for early diagnosis and proper treatment of this potentially fatal complication of stroke.

Aged↗

PubMed1995

Concurrent trigeminal, abducens, and facial nerve palsies presenting as false localizing signs: case report.

Multiple cranial nerve dysfunction presenting as false localizing signs is rare. We report a 20-year-old woman who had concurrent trigeminal sensory disturbance, abducens, and peripheral facial nerve palsies in association with a contralateral acoustic neuroma. After surgery, the trigeminal nerve disturbance and the abducens nerve palsy completely recovered, but the peripheral facial nerve palsy persisted. The nature of tumor, the presence of brain stem distortion, the anatomic variation of posterior fossa, and the relationships of cranial nerves and nearby blood vessels, which are factors influencing the occurrence of false localizing, are briefly discussed.

Abducens Nerve↗