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Biomedical subjects

Y H Chou

Publications and source records attributed to Y H Chou.

At least 55 records · Page 3Linked to original sources
PubMed2000

Texture analysis of breast tumors on sonograms.

We performed a feasibility study to determine if the texture features extracted from sonograms can be used to predict malignant or benign breast pathology by the proposed artificial neural network and to compare the diagnostic results with the radiologists' results. A total of 1,020 images (4 different rectangular regions from the 2 orthogonal imaging planes of each tumor) from 255 patients were used as samples. When a sonogram was performed, 1 physician identified the region of interest in the sonogram; then, a neural network model, using 24 autocorrelation texture features, classified the tumor as benign or malignant. Three radiologists who were unfamiliar with the samples also classified these images. The receiver operating characteristic (ROC) area index for the proposed neural network system is 0.9840 +/- 0.0072. The neural network identified 35 of 36 malignancies and 211 of 219 benign tumors using all 4 regions of interest. The radiologists, on average, identified 19 of 36 malignancies, with 12 tumors called indeterminate and 4 tumors called benign. We conclude that benign and malignant breast tumors can be distinguished using interpixel correlation in digital ultrasonic images.

Adolescent↗
PubMed2000

Candidaemia in special care nurseries: comparison of albicans and parapsilosis infection.

OBJECTIVES: Candidaemia caused by Candida parapsilosis (CP) is being increasingly reported among infants in neonatal intensive care units (NICU). To assess relative severity, clinical manifestations of candidaemia caused by C. albicans (CA) and CP in a NICU were compared. METHODS: Between January 1994 and July 1997, episodes of candidaemia occurring among infants hospitalized in the NICU were identified in a children's hospital. The demographic characteristics, associated risk factors, clinical manifestations and outcome of the infants with CP fungaemia were collected and compared with those of the infants with CA fungaemia. RESULTS: Twenty-four episodes caused by CA and 22 episodes caused by CP were included in this study. No significant differences were found between the two groups for gestational age, birth weight, male gender, post-natal age at onset of candidaemia, frequency of antecedent neonatal events, prior duration of antibiotic therapy and hyperalimentation, as well as presence of central venous catheter (CVC). Infants with CA fungaemia were significantly more likely than those with CP fungaemia to present with hypoxaemia, bradycardia and respiratory distress requiring intubation, and have a longer prior duration of indwelling CVC and a higher dissemination rate. The eradication rate of candidaemia and overall case fatality rate were comparable in both groups. but CP fungaemia did not appear to cause acute lethal events. CONCLUSION: The presenting signs of CP fungaemia are relatively not so severe, but CP fungaemia, which is relatively difficult to eradicate, increases the morbidity and mortality of the infants.

Blood↗
PubMed2000

Fluconazole therapy in neonatal candidemia.

We reviewed 62 episodes (from 59 infants) of neonatal candidemia that occurred between January 1994 and June 1999. Except 5 term babies, all infants were premature (median gestational age [GA], 30 weeks) and birth weight was less than 2,500 g (median, 1,300 g). Most infants had reported risk factors and other neonatal problems. The age at onset of candidemia ranged from 15 to 173 days with a median of 34 days. In addition to catheter removal, all but one infants received antifungal agents and candidemia was eradicated subsequently in 46 episodes (75%). Eighteen infants with 19 episodes ever received fluconazole therapy. Fluconazole was administered as the first line agent in 6 episodes and successfully cleared candidemia in 5 episodes. Fluconazole was used as an alternative agent in an additional 13 episodes after amphotericin B (am B) +/- flucytosine were given for a period without a satisfactory result and eradication of candidemia was achieved in 8 episodes subsequently. All 18 infants tolerated fluconazole well and no withdrawal was required on account of its adverse effect. In contrast, am B alone was administered as the first line agent in 55 episodes and successfully cleared candidemia in 32 episodes (58%). This retrospective analysis suggests that fluconazole appears to be safe in neonates and can be used as an alternative agent in treating neonatal candidemia. A large-scaled prospective study may be needed.

Antifungal Agents↗
PubMed2000

Mycotic aneurysm of the abdominal aorta in a patient undergoing hemodialysis: an unusual complication of Staphylococcus aureus bacteremia.

When Staphylococcus aureus is repeatedly positive in blood cultures even under effective antibiotics therapy (vancomycin, teicoplanin, or rifampin), computed tomography scan and sonography should be performed early to exclude mycotic aneurysm of the deeply seated arteries, especially in patients with abdominal aortic calcification. Before 1990, the most common causative organism of suprarenal aortic mycotic aneurysm was Salmonella; since 1990, it has been gram-positive cocci (i.e., Streptococcus and Staphylococcus) rather than gram-negative bacilli (i.e., Salmonella), possibly because of the more invasive procedures performed in clinical settings, but this hypothesis needs further investigation.

Aged↗
PubMed2000

Decreased dopamine transporter binding in Machado-Joseph disease.

UNLABELLED: The aim of this study was to use 99mTc-TRODAT-1 brain SPECT for investigation of the binding of dopamine transporter (DAT) in the nigrostriatal dopaminergic pathway of symptomatic Machado-Joseph disease (MJD) and to compare the results with the abnormal cytidylate, adenylate, and guanylate (CAG) expansion in the MJD1 gene and other clinical factors. METHODS: Ten symptomatic MJD patients (8 women, 2 men; age range, 20-71 y; mean age +/- SD, 36.4 +/- 10.6 y; mean duration of illness, 9.8 +/- 5.4 y) and 21 healthy volunteers (age range, 24-71 y; mean age, 47.6 +/- 20.1 y) were examined. Brain SPECT images were acquired 4 h after injection. The ratio of specific to nonspecific nigrostriatal 99mTc-TRODAT-1 binding was measured and compared with the clinical symptoms, duration of illness, and size of abnormal expanded CAG repeats. RESULTS: All nigrostriatal 99mTc-TRODAT-1 ratios were significantly lower in MJD patients than in healthy volunteers (P < 0.05). Discriminant function analysis of all MJD patients showed that the decreased binding of 99mTc-TRODAT-1 in the putamen was not significantly different from that in the caudate nucleus. Eight of 10 MJD patients had significantly decreased 99mTc-TRODAT-1 uptake. Of these 8, 2 had extrapyramidal signs and 6 had no obvious extrapyramidal signs. The other 2 patients, who had normal 99mTc-TRODAT-1 uptake, had no obvious extrapyramidal signs. CONCLUSION: Our findings indicate that 99mTc-TRODAT-1 brain SPECT is an appropriate method for evaluating damage to the nigrostriatal DAT in symptomatic MJD patients with and without extrapyramidal signs. The decreased binding of 99mTc-TRODAT-1 in the nigrostriatal dopaminergic pathway in symptomatic MJD patients correlates with the phenotype of extrapyramidal signs but not with the abnormal CAG repeat length, age at disease onset, or disease duration.

Adolescent↗
PubMed2000

Adrenal myelolipoma--report of two cases.

Adrenal myelolipoma, which is composed of hematopoietic and adipose elements, is a rare benign tumor. Most adrenal myelolipomas are asymptomatic and are found incidentally. We report two cases of adrenal myelolipoma. One was a middle-aged woman with right flank pain. Tumor size increased 8 years later. The other patient was a 63-year-old man presenting with right flank soreness. The right adrenal tumor was found by abdominal sonography. Both of them received adrenalectomy to relieve symptoms and the pathologic results showed adrenal myelolipoma. The clinical, radiologic and pathologic characteristics of these two cases are discussed together with a review of the literature.

Adrenal Gland Neoplasms↗
PubMed1999

Integrating the actin and vimentin cytoskeletons. adhesion-dependent formation of fimbrin-vimentin complexes in macrophages.

Cells adhere to the substratum through specialized structures that are linked to the actin cytoskeleton. Recent studies report that adhesion also involves the intermediate filament (IF) and microtubule cytoskeletons, although their mechanisms of interaction are unknown. Here we report evidence for a novel adhesion-dependent interaction between components of the actin and IF cytoskeletons. In biochemical fractionation experiments, fimbrin and vimentin coprecipitate from detergent extracts of macrophages using vimentin- or fimbrin-specific antisera. Fluorescence microscopy confirms the biochemical association. Both proteins colocalized to podosomes in the earliest stages of cell adhesion and spreading. The complex is also found in filopodia and retraction fibers. After detergent extraction, fimbrin and vimentin staining of podosomes, filopodia, and retraction fibers are lost, confirming that the complex is localized to these structures. A 1:4 stoichiometry of fimbrin binding to vimentin and a low percentage (1%) of the extracted vimentin suggest that fimbrin interacts with a vimentin subunit. A fimbrin-binding site was identified in the NH(2)-terminal domain of vimentin and the vimentin binding site at residues 143-188 in the CH1 domain of fimbrin. Based on these observations, we propose that a fimbrin-vimentin complex may be involved in directing the assembly of the vimentin cytoskeleton at cell adhesion sites.

Actins↗
PubMed1999

[Cerebral uptake and metabolism of (11C) Vinpocetine in monkeys: PET studies].

Vinpocetine, a vinca alkaloid, is a therapeutic agent widely used in the treatment of acute and chronic stroke patients. To explore the uptake and distribution of vinpocetine in the primate brain, vinpocetine was labelled with 11C and positron emission tomography (PET) was used to measure the uptake and distribution of 11C-vinpocetine in the brain and the trunk of a cynomolgous monkey. HPLC was used to determine the concentration of vinpocetine and its labelled metabolites in blood and plasma. Following the radioligand's intravenous administration, after an initial peak, the total concentration of radioactivity in blood was relatively stable with time. The uptake of 11C-vinpocetine into the brain was rapid and about 5% of the total injected radioactivity was present in the brain two minutes after drug administration. These facts indicate that the compound passes the blood-brain barrier readily and enters the brain. The radioactivity uptake was heterogeneously distributed among brain regions. The highest concentrations were found in the thalamus, the basal ganglia and certain neocortical regions. In an earlier PET investigation on chronic stroke patients the highest increases in cerebral blood flow and glucose metabolism after intravenous vinpocetine treatment occurred in these anatomical structures. The heterogenous regional distribution of vinpocetine and the observation that the highest uptake values in brain structures go parallel with the greatest regional blood flow and glucose metabolic rate increases indicate that direct CNS effects of vinpocetine should be considered as an explanation for the therapeutic effects. The confirmation of this suggestion requires further investigations.

Animals↗
PubMed1999

Induction of p21(CIP1/Waf1) and activation of p34(cdc2) involved in retinoic acid-induced apoptosis in human hepatoma Hep3B cells.

The biological activity of retinoic acid (RA) was examined in human hepatoma Hep3B cells. Under serum-deprived conditions, RA induced S/M-phase elevation and mitotic index increase within 24 h, followed by apoptosis. This RA-induced apoptosis was accompanied by p53-independent up-regulation of endogenous p21(CIPI/Waf1) and Bax proteins, as well as activation of p34(cdc2) kinase, and increase of Rb2 protein level and phosphorylation pattern. In addition, RA had no effect on the levels of Bcl-XL; Bcl-XS; cyclins A, B, D1, D3, or E; or Rb1 expression but markedly down-modulated Cdk2 kinase activity and reduced Cdk4 expression. RA also slightly delayed p27(Kip1) expression. Olomoucine, a potent p34(cdc2) and Cdk2 inhibitor, effectively blocked RA-mediated p34(cdc2) kinase activation and prevented RA-induced apoptosis. Furthermore, antisense oligonucleotide complementary to p21(CIP2/Waf1) and p34(cdc2) mRNA significantly rescued RA-induced apoptosis. Our data indicate that p21(CIP2/Waf1) overexpression may not be the only regulatory factor necessary for RA-induced apoptosis in human hepatoma Hep3B cells. RA treatment leads to Rb2 hyperphosphorylation, and p34(cdc2) kinase activation is coincident with an aberrant mitotic progression, followed by appearance of abnormal nucleus. This aberrant cell cycle progression appeared requisite for RA-induced cell death. These findings suggest that inappropriate regulation of the cell cycle regulators p21(CIP2/Waf1) and p34(cdc2) is coupled with induction of Bax and involved in cell death with apoptosis when Hep3B cells are exposed to RA.

Apoptosis↗
PubMed1999

A high molecular weight intermediate filament-associated protein in BHK-21 cells is nestin, a type VI intermediate filament protein. Limited co-assembly in vitro to form heteropolymers with type III vimentin and type IV alpha-internexin.

BHK-21 fibroblasts contain type III vimentin/desmin intermediate filament (IF) proteins that typically co-isolate and co-cycle in in vitro experiments with certain high molecular weight proteins. Here, we report purification of one of these and demonstrate that it is in fact the type VI IF protein nestin. Nestin is expressed in several fibroblastic but not epithelioid cell lines. We show that nestin forms homodimers and homotetramers but does not form IF by itself in vitro. In mixtures, nestin preferentially co-assembles with purified vimentin or the type IV IF protein alpha-internexin to form heterodimer coiled-coil molecules. These molecules may co-assemble into 10 nm IF provided that the total amount of nestin does not exceed about 25%. However, nestin does not dimerize with types I/II keratin IF chains. The bulk of the nestin protein consists of a long carboxyl-terminal tail composed of various highly charged peptide repeats. By analogy with the larger neurofilament chains, we postulate that these sequences serve as cross-bridgers or spacers between IF and/or other cytoskeletal constituents. In this way, we propose that direct incorporation of modest amounts of nestin into the backbone of cytoplasmic types III and IV IFs affords a simple yet flexible method for the regulation of their dynamic supramolecular organization and function in cells.

Animals↗
PubMed1999

Unusual clinical presentation of upper urothelial carcinoma in Taiwan.

BACKGROUND: The unusual clinical picture of transitional cell carcinoma (TCC) in Taiwan appears to be different from that reported elsewhere. METHODS: The authors reviewed their experience of 135 cases of pathologically proven TCC of the upper urinary tract. Data regarding the gender ratio and clinical presentation were analyzed. RESULTS: The male to female ratio was found to be 1 to 1.3, showing a slight female predominance. The ratio of TCC of the renal pelvis to TCC of the ureter to TCC of the bladder was noted to be approximately 1.1:0.9:8.0. TCC of the renal pelvis accounted for 10.7% of all urothelial TCC, and for approximately 40% of all renal carcinomas. CONCLUSIONS: The results of the current study found that the gender incidence and ratio of renal pelvis TCC to all renal carcinomas are different in Taiwan compared with data presented in the majority of other studies.

Adolescent↗
PubMed1999

Echo-enhancing sonography of a large-vessel hemangioma of the neck.

Because of the slow flow in the venous spaces of large-vessel hemangiomas, demonstration of color flow signals with conventional color Doppler or power Doppler sonography may be difficult. We report the case of a 22-year-old female patient with a soft tissue tumor containing multiple fluid-filled spaces in the right supraclavicular region. Gray-scale, color, and power Doppler sonography could not differentiate between cystic lymphangioma and large-vessel hemangioma. The intravenous echo-enhancing contrast agent Levovist was administered, and a significant echo-enhancing effect on color and power Doppler imaging was demonstrated in the fluid-filled spaces and lasted for about 3 minutes. Histopathologic study of the excised tumor confirmed the sonographic diagnosis of hemangioma. Levovist appears useful in depicting slow flow in a large-vessel hemangioma.

Adult↗
PubMed1999

A PET study of D(1)-like dopamine receptor ligand binding during altered endogenous dopamine levels in the primate brain.

RATIONALE: Several positron emission tomography (PET) studies have shown that radioligand binding to D(2)-like dopamine receptors competes with endogenous dopamine. OBJECTIVE: The purpose of this PET study was to examine the effect of amphetamine and reserpine on D(1)-like dopamine receptor binding. METHODS: Three Cynomolgus monkeys were examined with the radioligands [(11)C]SCH 23390 or [(11)C]NNC 112 at baseline condition and after pretreatment with amphetamine (2 mg/kg IV). The B/F values (binding potential) in the striatum and the neocortex were calculated at transient equilibrium. In two monkeys, the effect of the long-lasting dopamine depletion after reserpine (1 mg/kg IV) was followed by a repeated Scatchard procedure in up to 77 days after drug administration. The Scatchard analysis was based on two PET measurements with high and low specific radioactivity and allowed the calculation of D(1)-like dopamine receptor density (B(max)) and apparent affinity (K(D)(app)). RESULTS: The effect of amphetamine on the B/F values was between -14 and 6%. These changes can be considered as within the range of the test-retest reliability. Thus, there was no evident effect of amphetamine-induced dopamine release on D(1)-like dopamine receptor binding. Five hours after reserpine administration, there was no change in B(max) or K(D)(app). At 3, 23, and 28 days after reserpine administration, the Scatchard analyses indicated a 13-20% reduction in B(max) without any evident change in K(D)(app) in both the striatum and the neocortex. CONCLUSIONS: The lack of evident effects of amphetamine and reserpine on D(1)-like dopamine receptor binding is markedly different from the 20% amphetamine-induced decrease and 50% reserpine-induced increase that has been consistently reported for D(2)-like dopamine receptor binding. The data indicated that D(1)-like dopamine receptor occupancy of endogenous dopamine is low at physiological condition. It is thus unlikely that D(1)-like dopamine receptor radioligands can be used to measure changes in the concentration of endogenous dopamine.

Algorithms↗
PubMed1999

Congenital hypothyroidism with multiple ovarian cysts.

UNLABELLED: A case of ectopic thyroid with congenital hypothyroidism presenting with bilateral multicystic ovaries without marked precocious puberty is reported. The cystic ovaries disappeared dramatically after thyroid hormone therapy. CONCLUSION: When ovarian cysts are found in prepubescent females, the possibility of associated hypothyroidism should be considered.

Age Determination by Skeleton↗
PubMed1999

Implementation of spectral width Doppler in pulsatile flow measurements.

In this paper, we present an automatic beam-vector (Doppler) angle and flow velocity measurement method and implement it in pulsatile flow measurements using a clinical Doppler ultrasound system. In current clinical Doppler ultrasound flow velocity measurements, the axis of the blood vessel needs to be set manually on the B-scan image to enable the estimation of the beam-vector angle and the beam-vector angle corrected flow velocity (the actual flow velocity). In this study, an annular array transducer was used to generate a conical-shaped and symmetrically focused ultrasound beam to measure the flow velocity vectors parallel and perpendicular to the ultrasound beam axis. The beam-vector angle and flow velocity is calculated from the mode frequency (f(d)) and the maximum Doppler frequency (f(max)) of the Doppler spectrum. We develop a spectrum normalization algorithm to enable the Doppler spectrum averaging using the spectra obtained within a single cardiac cycle. The Doppler spectrum averaging process reduces the noise level in the Doppler spectrum and also enables the calculation of the beam-vector angle and flow velocity for pulsatile flows to be measured. We have verified the measurement method in vivo over a wide range of angles, from 52 degrees to 80 degrees, and the standard deviations of the measured beam-vector angles and flow velocities in the carotid artery are lower than 2.2 degrees and 12 cm/s (about 13.3%), respectively.

Blood Flow Velocity↗
PubMed1999

PET examination of three potent cocaine derivatives as specific radioligands for the serotonin transporter.

Several positron emission tomography (PET) radioligands based on the aryl tropane structure have been used for studies on monoamine reuptake sites. RTI-364, RTI-330, and RTI-357 (3-beta-(4'-n-propyl-,4'-iso-propyl-, and 4'-iso-propenyl-phenyl)nortropane-2-beta-carboxylic acid methyl ester) are three recently synthesized cocaine analogues with higher affinity for the serotonin (5-HTT) than the dopamine transporter (DAT). Unlabelled RTI-364 and RTI-330 were prepared in a two-step synthesis. The key step was the addition of the appropriate propyl Grignard reagent to anhydroecgonine methyl ester. RTI-357 was prepared in a three-step synthesis with a palladium-catalyzed coupling reaction of beta-CIT and isopropenylzinc bromide as key step. Hydrolysis of the ester functions gave the carboxylic acid analogues of RTI-364, RTI-330, and RTI-357, which were labelled with 11C using [11C]methyl iodide in dimethyl formamide (DMF) and tetrabutylammonium hydroxide (TBAH) as base. All three compounds entered the monkey brain in a high degree (approximately 5-10%). There was a low uptake of [11C]RTI-364 in serotonin-rich brain areas, whereas [11C]RTI-330 and [11C]RTI-357 showed a marked uptake of radioactivity in the thalamus and the brainstem, regions known to contain serotonin transporters. Transient equilibrium was reached at 15 and 40 min for [11C]RTI-330 and [11C]RTI-357, respectively. After pretreatment with citalopram, the ratio of radioactivity in the thalamus and the brainstem to the cerebellum were markedly reduced for [11C]RTI-357 but not for [11C]RTI-330. The results indicate that [11C]RTI-357 is a potential PET radioligand for quantitation of the serotonin reuptake site.

Animals↗
PubMed1999

Variations in ocular hemodynamics in patients with early and late glaucoma.

PURPOSE: To determine the retrobulbar hemodynamics in glaucoma patients with different degrees of optic nerve damage. METHODS: Color Doppler imaging was performed in 52 patients with controlled primary open angle glaucoma (POAG) and in 25 control subjects. Glaucomatous eyes were divided into early and late groups based on the perimetry findings. Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistive index of the central retinal artery (CRA) and posterior ciliary arteries (PCA) were evaluated. RESULTS: Early glaucoma showed significantly decreased PSV in nasal PCA when compared with the normal. Late glaucoma showed significantly decreased PSV and EDV in the CRA and nasal PCA, and significantly decreased PSV in temporal PCA as compared with the control and early glaucoma. The resistive index of the CRA also increased significantly in late glaucoma. CONCLUSION: Eyes with advanced glaucomatous optic neuropathy were associated with more marked alterations in retrobulbar circulation than eyes with less nerve damage.

Aged↗