Search PubMed⌕ Search

Biomedical subjects

S Chang

Publications and source records attributed to S Chang.

At least 37 records · Page 2Linked to original sources
PubMed2001

Clinicopathologic findings in eyes with retained perfluoro-n-octane liquid.

OBJECTIVE: To describe the clinical and histopathologic findings in five eyes with retained perfluoro-n-octane (PFO) liquid after retinal reattachment surgery. DESIGN: Retrospective, noncomparative, clinicopathologic case series. PARTICIPANTS: Surgical specimens from five eyes were studied. METHODS: Surgical specimens from eyes with prior intraoperative PFO use submitted to the W. Richard Green Eye Pathology Laboratory at the Wilmer Ophthalmological Institute were identified and reviewed. MAIN OUTCOME MEASURES: Histopathologic analysis and energy dispersive spectroscopy identified intracellular vacuoles containing PFO. RESULTS: Five cases were identified. Three specimens were obtained at the time of further surgery for recurrent retinal detachment; one at repeat penetrating keratoplasty, and one at removal of retained PFO. Each eye had macroscopic white flake-like material on intraocular structures noted before or during surgery. Histopathologic analysis disclosed an inflammatory response featuring macrophages with intracellular vacuoles containing PFO. Removal of the PFO in all five eyes combined with repeat retinal reattachment surgery in three eyes resulted in resolution of the inflammatory response. CONCLUSIONS: Retention of PFO after surgery elicits an inflammatory response. We suspect that young patients, those with considerable residual vitreous gel, and eyes with larger amounts of retained PFO may be at higher risk for this complication.

Adolescent↗
PubMed2001

Granulysin expression is a marker for acute rejection and steroid resistance in human renal transplantation.

Differentiating etiologies of transplant dysfunction without biopsy and optimizing therapy for acute rejection by predicting steroid resistance will reduce patient morbidity. Granulysin is a cytolytic molecule released by CTL and NK cells and coexpressed with effectors of acute allograft rejection, like perforin and granzymes. Granulysin mRNA and protein expression were studied in peripheral blood lymphocytes (PBL; n = 61 total, n = 10 with intercurrent infections) and biopsy tissue from adult and children renal transplant recipients (n = 97) by competitive quantitative-reverse transcriptase-PCR (QC-RT-PCR) and immunohistochemistry. Differences in cell phenotypes were studied in steroid sensitive and resistant acute rejection biopsies. Granulysin was studied in phytohemagglutinin (PHA) stimulated cell lines (donor PBL and CD45RO(+) T cells) by FACS, Western blotting, and RT-PCR after pretreating with cyclosporine A (CSA), azathioprine, mycophenolic acid, and steroids. Granulysin mRNA was significantly increased in patient PBL and transplant biopsies during acute rejection (p < 0.0001) and infection (p < 0.001). Rejecting biopsies alone (n = 53) had mononuclear cell granulysin staining. Steroid resistant biopsies (n = 25) had denser granulysin staining (>2 cells/high power field) and CD45RO(+) lymphocytes, when compared with steroid sensitive (n = 28) rejecting tissue. Granulysin levels were unchanged after azathioprine and mycophenolic acid treatment, decreased after treating activated PBL with steroids and cyclosporine A (CSA), and paradoxically, increased (p < 0.05) after treating CD45RO(+) CTL with CSA. Elevated PBL granulysin is a peripheral marker for acute rejection and infection and dense granulysin staining a tissue marker for steroid resistance. Memory CTL abound in steroid resistant grafts and may have a markedly different response to CSA immunotherapy, suggesting a possible mechanism for steroid resistance.

Acute Disease↗
PubMed2001

Three-dimensional magnetic resonance spectroscopic imaging of histologically confirmed brain tumors.

The goal of this study was to determine whether presurgical metabolite levels measured by 3D MR Spectroscopic Imaging (MRSI) can accurately detect viable cancer within human brain tumor masses. A total of 31 patients (33 exams, 39 pathology correlations) with brain tumors were studied prior to surgical biopsy and/or resection. The 3D MRSI was obtained with a spatial resolution of 0.2 to 1 cc throughout the majority of the mass and adjacent brain tissue using PRESS-CSI localization. Levels of choline, creatine and NAA were estimated from the locations of the resected tissue and normalized to normal appearing brain tissue. The data were correlated with subsequent histologic analysis of the biopsy tissue samples. Although there were large variations in the metabolite ratios, all regions of confirmed cancer demonstrated significant choline levels and a mean choline/NAA ratio of 5.84 + 2.58 with the lowest value being 1.3. This lowest value is greater than 4 standard deviations above the mean (0.52 +/- 0.13) found in 8 normal volunteers. The choline signal intensities in confirmed cancers were significantly elevated compared to normal appearing brain tissue with a mean ratio of 1.71 +/- 0.69. Spectra with no significant metabolite levels were observed in the non-enhancing necrotic core of the tumor masses. The results of this study indicate that 3D MRSI of brain tumors can detect abnormal metabolite levels in regions of viable cancer and grades and can differentiate cancer from necrosis and/or normal brain tissue.

Biomarkers, Tumor↗
PubMed2001

The Immunology Case Registry.

The Veterans Health Administration (VA) is the nation's largest public integrated health care system and the largest single provider of health care to HIV-positive patients in the United States. First established in 1992, the Immunology Case Registry (ICR) is a national-level administrative database originally designed to monitor health care service utilization. With its interface to the VA electronic medical record, the ICR provides an opportunity to monitor and improve the quality of clinical care for HIV-positive patients receiving VA care. To realize this potential, key data element enhancements and quality review systems are being put into place. A brief description of the population included in the ICR is provided, along with current data limitations and planned improvements for data collection. The ICR, now managed by a national quality management center, is being updated and systematically improved for local clinical use. As local data capture improves, the ICR will prove to be an invaluable resource for assessing the quality of HIV care in the VA system and patient outcomes from that care.

Adult↗
PubMed2001

The truncated cytoplasmic tail of HLA-G serves a quality-control function in post-ER compartments.

In contrast to the current model of MHC class I trafficking, which predicts that once a MHC class I molecule leaves the ER, it moves to the cell surface by bulk flow, we show that HLA-G that is loaded with suboptimal peptides is retrieved from post-ER compartments to the ER. Loading of HLA-G with high-affinity peptides abrogates this retrieval due to the lack of binding affinity to coatomer. Moreover, the loss of the endocytosis motif in the truncated cytoplasmic tail results in the prolonged half-life of HLA-G on the cell surface. Our findings reveal that surface expression of HLA-G can be further regulated in post-ER compartments and that the truncated cytoplasmic tail plays a critical role in such quality-control mechanisms.

Amino Acid Motifs↗
PubMed2001

Glutamate regulates actin-based motility in axonal filopodia.

The dynamics of axonal arbors during synaptogenesis and their plasticity in the adult nervous system remain poorly understood. Axonal filopodia, which emerge from the shaft of axonal branches and contain small synaptic vesicle clusters, initiate synaptic formation. We found that the movement of axonal filopodia is strongly inhibited by the neurotransmitter glutamate. This inhibitory effect is local, requires extracellular Ca2+, and can be blocked by CNQX treatment but not by NMDA, implicating axonal AMPA/kainate glutamate receptors. Transport and exo-endocytic recycling of synaptic vesicle packages in filopodia are not affected. These results reveal that the effect of glutamate on axonal filopodia is similar to its previously described effect on dendritic spines. Our results raise the possibility that axonal ionotropic glutamate receptors are also involved in synaptic plasticity in the adult nervous system.

Actins↗
PubMed2001

Multidisciplinary management of adult anaplastic astrocytomas.

The management of patients with anaplastic astrocytoma (AA) requires multidisciplinary involvement. In this article, the literature on the treatment of patients with AA is reviewed, emphasizing randomized trials and key retrospective studies. The role of surgery, radiation therapy, and chemotherapy in newly diagnosed patients and those with recurrent disease is described. Basic science insights, advances in neuroimaging and neuropathology, and novel therapies targeting invasion, angiogenesis, and growth modulation will hopefully lead to improved outcome in this subset of patients with malignant glioma.

Adult↗
PubMed2001

The injured intoxicated driver: analysis of the conviction process.

BACKGROUND: The widespread nature of alcohol-related motor vehicle collisions suggests inadequacies in the system for deterring alcohol use when driving. This study was performed to determine whether hospitalization is a component in a "system failure" that allows injured, alcohol-impaired drivers to escape arrest and conviction for driving under the influence (DUI). METHODS: We conducted a retrospective review of medical and court records of intoxicated drivers injured in a motor vehicle collision who were transported to our Level I trauma center from January 1, 1997, through December 31, 1998. RESULTS: Of the 213 intoxicated drivers in our study, 172 (81%) were followed up by law enforcement officials, and 156 (73.2%) were arrested for DUI. Of those who were arrested and completed court hearings, 135 (93.8%) were convicted for DUI. CONCLUSION: These values are higher than those reported in previous studies and indicate that hospitalization does not "protect" injured, intoxicated drivers in our community.

Accidents, Traffic↗
PubMed2001

Regional variation in myosin isoforms and phosphorylation at the resting tone in urinary bladder smooth muscle.

Urinary bladder filling and emptying requires coordinated control of bladder body and urethral smooth muscles. Bladder dome, midbladder, base, and urethra showed significant differences in the percentage of 20-kDa myosin light chain (LC20) phosphorylation (35.45 +/- 4.6, 24.7 +/- 2.2, 13.6+/- 2.1, and 12.8 +/- 2.7%, respectively) in resting muscle. Agonist-mediated force was associated with a rise in LC20 phosphorylation, but the extent of phosphorylation at all levels of force was less for urethral than for bladder body smooth muscle. RT-PCR and quantitative competitive RT-PCR analyses of total RNA from bladder body and urethral smooth muscles revealed only a slight difference in myosin heavy chain mRNA copy number per total RNA, whereas mRNA copy numbers for NH2-terminal isoforms SM-B (inserted) and SM-A (noninserted) in these muscles showed a significant difference (2.28 x 10(8) vs. 1.68 x 10(8) for SM-B and 0.12 x 10(8) vs. 0.42 x 10(8) for SM-A, respectively), which was also evident at the protein level. The ratio of COOH-terminal isoforms SM2:SM1 in the urethra was moderately but significantly lower than that in other regions of the bladder body. A high degree of LC20 phosphorylation and SM-B in the bladder body may help to facilitate fast cross-bridge cycling and force generation required for rapid emptying, whereas a lower level of LC20 phosphorylation and the presence of a higher amount of SM-A in urethral smooth muscle may help to maintain the high basal tone of urethra, required for urinary continence.

Animals↗
PubMed2001

Phenotypic analysis of conditionally immortalized cells isolated from the BPK model of ARPKD.

To study the pathophysiology of autosomal recessive polycystic kidney disease (ARPKD), we sought to develop conditionally immortalized control and cystic murine collecting tubule (CT) cell lines. CT cells were isolated from intercross breedings between BPK mice (bpk(+/-)), a murine model of ARPKD, and the Immorto mice (H-2K(b)-ts-A58(+/+)). Second-generation outbred offspring (BPK x Immorto) homozygous for the BPK mutation (bpk(-/-); Im(+/+/-); cystic BPK/H-2K(b)-ts-A58), were phenotypically indistinguishable from inbred cystic BPK animals (bpk(-/-)). Cystic BPK/H-2K(b)-ts-A58 mice developed biliary ductal ectasia and massively enlarged kidneys, leading to renal failure and death by postnatal day 24. Principal cells (PC) were isolated from outbred cystic and noncystic BPK/H-2K(b)-ts-A58 littermates at specific developmental stages. Epithelial monolayers were under nonpermissive conditions for markers of epithelial cell polarity and PC function. Cystic and noncystic cells displayed several properties characteristic of PCs in vivo, including amiloride-sensitive sodium transport and aquaporin 2 expression. Cystic cells exhibited apical epidermal growth factor receptor (EGFR) mislocalization but normal expression of ZO-1 and E-cadherin. Hence, these cell lines retain the requisite characteristics of PCs, and cystic BPK/H-2K(b)-ts-A58 PCs retained the abnormal EGFR membrane expression characteristic of ARPKD. These cell lines represent important new reagents for studying the pathogenesis of ARPKD.

Animals↗
PubMed2001

Health and federal budgetary effects of increasing access to antiretroviral medications for HIV by expanding Medicaid.

UNLABELLED: OBJECTIVES. This study modeled the health and federal fiscal effects of expanding Medicaid for HIV-infected people to improve access to highly active antiretroviral therapy. METHODS: A disease state model of the US HIV epidemic, with and without Medicaid expansion, was used. Eligibility required a CD4 cell count less than 500/mm3 or viral load greater than 10,000, absent or inadequate medication insurance, and annual income less than $10,000. Two benefits were modeled, "full" and "limited" (medications, outpatient care). Federal spending for Medicaid, Medicare, AIDS Drug Assistance Program, Supplemental Security Income, and Social Security Disability Insurance were assessed. RESULTS: An estimated 38,000 individuals would enroll in a Medicaid HIV expansion. Over 5 years, expansion would prevent an estimated 13,000 AIDS diagnoses and 2600 deaths and add 5,816 years of life. Net federal costs for all programs are $739 million (full benefits) and $480 million (limited benefits); for Medicaid alone, the costs are $1.43 and $1.17 billion, respectively. Results were sensitive to awareness of serostatus, highly active antiretroviral therapy cost, and participation rate. Strategies for federal cost neutrality include Medicaid HIV drug price reductions as low as 9% and private insurance buy-ins. CONCLUSIONS: Expansion of the Medicaid eligibility to increase access to antiretroviral therapy would have substantial health benefits at affordable costs.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Nursing skill assessment within populations: scale development and testing.

This study examined the reliability and validity of an instrument to measure the skill level of registered nurses within an Australian state. Internal consistency and construct validity of the scale and subscales were investigated in a sample of 1223 registered nurses from varying practice areas. The scale consisted of 105 skills within 13 practice domains: nursing practice, professional practice, acute care, community and public health, rural and remote area nursing, service delivery, self-management, supervision, resource management, improving processes, training and development, research, and technology. Twelve subscales obtained reliability co-efficients of 0.85 or more, with one at 0.81. The 13 factors explained 64.5 per cent of the cumulative variance, adequately capturing the concept of nursing skill. This scale, and its subscales, represent valid and reliable tools for the assessment and monitoring of skill levels in a population of nurses, within some limitation.

Australia↗
PubMed2001

Recurrent cardiac myxoma with multiple distant metastasis and malignant change.

A 37 year-old female underwent open heart surgery for a left atrial myxoma. The post-operative course was uneventful and she was discharged two weeks later. She had regular monthly follow-up in the outpatient department until 10 months postoperatively when she was readmitted to the orthopedic ward for excision of a left ankle tumor. Two days after admission, she developed severe orthopnea. The initial diagnosis was heart failure, and she was transferred to the medical ward for treatment. Transthoracic and transesophageal echocardiography revealed a recurrent left atrial tumor. Because of acute obstruction of the mitral valve and deterioration of her condition, she underwent emergent open heart surgery. The recurrent atrial tumor was excised; histopathologic examination revealed a myxoid sarcoma. Multiple tumors were found on this admission, including a mass in the neck and in the left forearm; computed tomography revealed a brain tumor in the left posterior frontal lobe and a chest wall tumor. She died two months later. Recurrent cardiac myxoma with multiple distant metastasis may have a malignant potential. Because of the potential for tumor recurrence, long-term and regular follow-up is mandatory.

Adult↗
PubMed2001

Serial proton MR spectroscopic imaging of recurrent malignant gliomas after gamma knife radiosurgery.

BACKGROUND AND PURPOSE: The diagnosis of brain tumors after high-dose radiation therapy is frequently limited by the lack of metabolic discrimination available with conventional imaging methods. The purpose of this study was to use proton MR spectroscopy to investigate serial changes in recurrent malignant gliomas after gamma knife radiosurgery to characterize tissue response to high-dose radiation. METHODS: Eighteen patients with recurrent gliomas were studied with MR imaging and 3D proton MR spectroscopic imaging at the time of radiosurgery and at regular time points thereafter. Choline (Cho) and N-acetyl aspartate levels were calculated on a voxel-by-voxel basis and compared with levels found in normal tissue and with levels observed at previous time points. The results of the spectral analysis were then compared with the radiologic findings. Statistical comparisons were precluded by the small sample sizes involved. RESULTS: Response within the gamma knife target was observed as a reduction of Cho levels and an increase in lactate/lipid levels, typically within 6 months of treatment. Increases in Cho correlated with poor radiologic response and suggested tumor recurrence, confirmed histologically in six cases. The development of a spectral abnormality preceded a coincident increase in contrast enhancement by 1 to 2 months in nine cases. CONCLUSION: Proton MR spectroscopic imaging provided diagnostic and monitoring information before and after radiosurgery. Evaluation of metabolic changes with proton MR spectroscopy and structural changes with MR imaging improved tissue discrimination and provided correlation with histologic findings.

Adult↗
PubMed2001

[Super heavy oil produced water treatment by surface flow constructed wetland].

This paper adopts a new economic technology of treating super heavy oil produced water using surface flow reed wetland system. The field test was conducted at the average filtration rate of 3.33 cm/d. The average influent concentrations per year of COD, Oil, BOD5, TN were 459.16 mg/L, 27.65 mg/L, 33.52 mg/L, 13.74 mg/L, and the average effluent concentrations per year of above indices were 77.21 mg/L, 1.42 mg/L, 3.90 mg/L, 1.60 mg/L, respectively. Its respective removal ratios of COD, Oil, BOD5, TN and pH were 83.18%, 94.86%, 88.37%, 88.36%, 7.87-7.77. Analyses showed that super heavy oil produced water had no obvious effect on soil and almost no effect on growth volume and quality of reeds. Results indicated that the surface flow reed wetland could provide an efficient economical, stable new means of treating super heavy oil produced water.

Fuel Oils↗
PubMed2001

Biomedical image skeletonization: a novel method applied to fibrin network structures.

To understand the rheological behavior of fibrin clots, we must obtain quantitative measurements of morphometric parameters of the networks formed under various conditions. The networks are so complex that researchers must currently manually segment the images of network samples and estimate the parameters from them. Skeletonization is a promising tool for automating this task. We here propose a method that rapidly constructs a coarse representation of a skeleton graph and, using the snake model, deforms the graph to obtain smooth skeletons. Unlike many existing approaches, our method does not involve explicit object boundary information or high order derivatives. Since our method processes a given image as a whole, the presence of multiple objects in an image is automatically detected and the skeletons of these objects are computed simultaneously.

Algorithms↗
PubMed2001

[Narcolepsy in a prepubertal boy].

We reported a 10-year-old boy with narcolepsy, the onset of which was at the age of 8 years and 6 months. The initial symptom was excessive daytime sleepiness, followed by cataplexy and disrupted nocturnal sleep. There was neither hallucination nor sleep paralysis. A daytime polysomnogram showed a sleep-onset rapid eye movement period (SOREMP), and human leukocyte antigen (HLA) analysis revealed HLA-DR2/DQB1 * 0602. Treatment with methylphenidate and clomipramine was effective; methylphenidate (30 mg/day) improved his wakefulness and alertness throughout the day, and clomipramine (20 mg/day) reduced the number of cataplexic episodes. Because of their abnormal behavior, prepubertal narcoleptic children may often be misdiagnosed as having epilepsy or an attention deficit hyperactivity disorder. Therefore, they need early diagnosis and treatment. Assistance should be provided to protect them from being labeled as lazy by their parents and school teachers.

Child↗