Biomedical subjects

Mei-Hsiu Chen

Publications and source records attributed to Mei-Hsiu Chen.

15 recordsLinked to original sources

PubMed2007

Validity of prostate-specific antigen as a tumour marker in men with prostate cancer managed by watchful-waiting: correlation with findings at serial endorectal magnetic resonance imaging and spectroscopic imaging.

OBJECTIVE: To investigate the validity of prostate-specific antigen (PSA) as a tumour marker in men with clinically localized prostate cancer who have selected watchful waiting, by determining if serial PSA level measurements are correlated with findings of malignancy or benign prostatic hyperplasia (BPH) at serial endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI). PATIENTS AND METHODS: We retrospectively identified 69 men with biopsy-proven prostate cancer being managed by watchful waiting, who underwent serial endorectal MRI/MRSI and who had contemporaneous serial PSA measurements. The mean (range) follow-up was 392 (294-571) days. A panel of three experienced readers reviewed the initial and follow-up MRI/MRSI studies, and classified findings of prostate cancer as stable or progressive. Another reader assessed BPH by calculating total gland and central gland volumes on all studies. RESULTS: At the follow-up MRI/MRSI, 51, 17 and one patient had stable, progressive, or unevaluable prostate cancer, respectively. The mean PSA velocity was significantly greater in patients with radiologically progressive disease (1.42 vs 0.42 ng/mL/year, P = 0.04). A PSA velocity of >0.75 ng/mL/year identified those with radiologically progressive disease with a true-positive fraction of 0.71 and a false-positive fraction of 0.39. PSA levels were not correlated with changes in total or central gland volumes (P > 0.05). CONCLUSIONS: In men with clinically localized prostate cancer who select watchful waiting, serial PSA levels are correlated with findings of malignancy but not BPH at serial endorectal MRI/MRSI, suggesting that PSA is a useful longitudinal tumour marker in this population.

Aged↗

PubMed2006

Gelatin-tricalcium phosphate membranes immobilized with NGF, BDNF, or IGF-1 for peripheral nerve repair: an in vitro and in vivo study.

In the present study, NGF, BNDF from the neurotrophin family and IGF-1 were covalently immobilized on gelatin-tricalcium phosphate (GTG) membrane using carbodiimide. We investigated the effects of these growth factors released from the GTG composites on cultured PC12 cells and sciatic nerve regeneration across a 10-mm-long gap in rats. In PC12 cell culture, the total protein content and MTT assay indicated more cell attachment on the composites modified with growth factors. The IGF-1 group showed a higher survival promotion effect on PC12 cells than did BDNF and NGF groups. On the other hand, NGF released from the composite showed the highest level of neuritogenesis for PC12 cells in neurite outgrowth assay. In the animal study, the GTG conduits modified with various growth factors were well tolerated by the host tissue. In the regenerated nerves, the number of the axons per unit area of the BDNF group was significantly higher than that of NGF and GTG groups but similar to that of IGF-1 group. However, the average axon size was the largest in NGF group. This result was in concordance with the neurite outgrowth assay in which NGF showed the highest neuritogenic potential. In the assessment of motor and sensory recovery after nerve repair, conduits modified with various neurotrophic factors showed a more favorable outcome in compound muscle action potential. The BDNF group had a better gastrocnemic muscle weight ratio than blank GTG repair. Nevertheless, the different effects of GTG conduits modified with various neurotrophic factors on functional recovery cannot be simply illustrated in the sciatic function index.

Animals↗

PubMed2006

MRI features of an infected cephalhaematoma in a neonate.

Bacterial infection of a cephalhaematoma is rare and has been associated with needle aspiration of the haematoma, placement of scalp electrodes and systemic sepsis. Clinical diagnosis of infected cephalhaematoma is difficult without obvious evidence of local infection. The role of imaging in differentiating infected from non-infected cephalhaematoma has not been clearly established. Needle aspiration is considered mandatory for suspected cases. In this report, we present the magnetic resonance imaging (MRI) findings of a 23-day-old neonate with an infected cephalhaematoma. Cephalhaematoma is a subperiosteal accumulation of blood, thus the diagnosis of infected cephalhaematoma was made as the MRI showed an accumulation of blood under thick, contrast-enhancing periosteum in the presented case. Without a diagnostic puncture, the decision for surgical intervention was made before complicating osteomyelitis developed. Early intervention with simple incision and drainage resulted in prompt improvement.

Anti-Bacterial Agents↗

PubMed2006

An in vivo study of tricalcium phosphate and glutaraldehyde crosslinking gelatin conduits in peripheral nerve repair.

In order to modulate the mechanical properties of gelatin, we previously developed a biodegradable composite composed by tricalcium phosphate and glutaraldehyde crosslinking gelatin (GTG) feasible for surgical manipulation. In this study, we evaluated the in vivo applications of GTG conduit for peripheral nerve repair. The effect of sciatic nerve reconstruction was compared between resorbable permeable GTG conduits and durable impermeable silicone tubes. Traditional methods of assessing nerve recovery following peripheral nerve repair including histomorphometric and electrophysiologic features were conducted in our study. In addition, autotomy score and sciatic function index (SFI) in walking tract analysis were used as additional parameters for assessing the return of nerve function. Twenty-four weeks after sciatic nerve repair, the GTG conduits were harvested. Microscopically, regeneration of nerves was observed in the cross-section at the mid portion of all implanted GTG conduits. The cross-sectional area of regenerated nerve of the GTG group was significant larger than that of the silicone group. In the compound muscle action potentials (CMAP), the mean recovery index of CMAP amplitude was 0.24 +/- 0.02 for the silicone group, 0.41 +/- 0.07 for the GTG group. The mean SFI increased with time in the GTG group during the evaluation period until 24 weeks. Walking tract analysis showed a higher SFI score in the GTG group at both 12 and 24 weeks. The difference reached a significant level at 24 weeks. Thus, the histomorphometric, electrophysiologic, and functional assessments demonstrate that GTG can be a candidate for peripheral nerve repair.

Action Potentials↗

PubMed2006

MRI of arthritis: comparison of ultrasmall superparamagnetic iron oxide vs. Gd-DTPA.

PURPOSE: To compare the ability of the ultrasmall superparamagnetic iron oxide (USPIO) SHU555C vs. gadopentetate dimeglumine (Gd-DTPA) to detect antigen-induced monoarthritis with MRI. MATERIALS AND METHODS: Twelve seven-week-old female rats with an antigen-induced monoarthritis of the right knee were randomly assigned to two groups. Animals in group I (N = 6) underwent MRI using T1-weighted gradient-echo sequences before injection and at 2, 9, 17, 25, 33, 40, 47, 55, and 63 minutes postinjection (p.i.) of Gd-DTPA on day 1, and before injection and at 3, 23, 43, and 123 minutes p.i. of SHU555C on day 2. Animals in group II (N = 6) were imaged before injection and at 3, 23, 43, and 123 minutes p.i. using identical sequences. Signal-to-noise ratios (SNRs) and relative enhancement (DeltaSI%) of arthritic and normal synovium were determined from region-of-interest (ROI) measurements in consensus reading by two experienced radiologists. Data were tested for significant differences between the two agents and between the arthritic and normal knees using a mixed-effect model and F-tests (P < 0.05). Joints were processed for histopathology as the gold standard. RESULTS: USPIO and Gd-DTPA showed significant enhancement differences (P < 0.001). USPIO provided a progressive and persistent enhancement of arthritic joints while Gd-DTPA provided an early and rapidly declining enhancement. Maximal enhancement in synovitis was 400% at 40-120 minutes p.i. of USPIO vs. 300% at two minutes p.i. of Gd-DTPA. USPIO provided a significant higher difference in enhancement between the arthritic and normal synovium than Gd-DTPA (P < 0.001). Histopathology confirmed marked inflammatory synovial changes in all arthritis-induced right knee joints and normal synovium in all left knee joints. CONCLUSION: Both USPIO and Gd-DTPA detect arthritis by positive T1-enhancement. Compared to standard Gd-DTPA, the USPIO SHU555C provides a comparable maximal T1-enhancement (at two minutes p.i for Gd-DTPA and between 43 and 123 minutes p.i. for SHU555C), but in addition it provides a prolonged T1-enhancement of synovitis and a higher difference between the relative enhancement of arthritic and normal synovium.

Animals↗

PubMed2006

Ultrasmall supraparamagnetic iron oxide-enhanced magnetic resonance imaging of antigen-induced arthritis: a comparative study between SHU 555 C, ferumoxtran-10, and ferumoxytol.

OBJECTIVES: We sought to compare the ability of 3 ultrasmall superparamagnetic iron oxides (USPIOs) to detect and characterize antigen-induced arthritis with MR imaging. MATERIALS AND METHODS: A monoarthritis was induced in the right knee of 18 rats. The left knee served as a normal control. Knees underwent magnetic resonance (MR) imaging before, up to 2 hours, and 24 hours after injection (p.i.) of 200 mumol Fe/kg SHU 555 C (n= 6), ferumoxtran-10 (n = 6), or ferumoxytol (n = 6), using T2-2D-SE 100/20,40,60,80/90 (TR/TE/flipangle), T2*-3D-spoiled gradient recalled (SPGR) 100/15/38, and T1-3D-SPGR 50/1,7/60 sequences. RESULTS: Quantitative signal to noise ratio and DeltaSI data of arthritic knees on T1- and T2*-weighted MR images showed no significant differences between the 3 USPIOs (P > 0.05). At 2 hours p.i., SNR and DeltaSI data were significantly increased from baseline on T1-weighted images and significantly decreased on T2*-weighted images (P < 0.001). At 24 hours p.i., the T1-enhancement returned to baseline, whereas the T2*-enhancement remained significantly elevated (P < 0.001). Immunostains demonstrated an USPIO compartmentalization in macrophages in the arthritic synovium. CONCLUSIONS: Based on the relatively small number of animals in our study group, inflammation in antigen-induced arthritis can be equally detected and characterized with any of the three USPIOs evaluated.

Animals↗

PubMed2005

Ultrasmall superparamagnetic iron-oxide-enhanced MR imaging of normal bone marrow in rodents: original research original research.

RATIONALE AND OBJECTIVES: The objective is to compare three different ultrasmall superparamagnetic iron oxides (USPIOs) for magnetic resonance (MR) imaging of normal bone marrow in rodents. MATERIALS AND METHODS: Femoral bone marrow in 18 Sprague-Dawley rats was examined by using MR imaging before and up to 2 and 24 hours postinjection (PI) of 200 mumol of Fe/kg of SHU555C (n = 6), ferumoxtran-10 (n = 6), or ferumoxytol (n = 6), using T1-weighted (50 ms/1.7 ms/60 degrees = repetition time [TR]/echo time [TE]/flip angle) and T2*-weighted (100 ms/15 ms/38 degrees = TR/TE/flip angle) three-dimensional spoiled gradient recalled echo sequences. USPIO-induced bone marrow was evaluated qualitatively and quantified as signal-to-noise ratio (SNR) and change in signal intensity (DeltaSI) values. A mixed-effect model was fitted to the SNR and DeltaSI values, and differences among USPIOs were tested for significance by using F tests. RESULTS: At 2 hours PI, all three USPIOs showed marked positive signal enhancement on T1-weighted images and a corresponding marked signal loss on T2*-weighted images. At 24 hours PI, the T1 effect of all three USPIOs disappeared, whereas T2*-weighted images showed persistent signal loss on SHU555C and ferumoxytol-enhanced MR images, but not ferumoxtran-10-enhanced MR images. Corresponding SNR and DeltaSI values on T2*-weighted MR images at 24 hours PI were significantly different from baseline for SHU555C and ferumoxytol, but not ferumoxtran-10. CONCLUSION: All three USPIO contrast agents, ferumoxtran-10, ferumoxytol, and SHU555C, can be applied for MR imaging of bone marrow. Ferumoxtran-10 apparently reveals a different kinetic behavior in bone marrow than ferumoxytol and SHU555C.

Animals↗

PubMed2004

Thyroid papillary carcinoma in subhyoid ectopic thyroid tissue.

Ectopic thyroid tissue is a rare entity in thyroidology; however, the occurrence of thyroid carcinoma in such aberrant thyroid tissue has been reported. Carcinoma arising in subhyoid thyroid is especially unusual, with even fewer reports published. Usually, surgical excision is considered to be therapeutic strategy for managing possible malignancy in ectopic thyroid. Thyroid ultrasonography, radioactive iodine scanning, and fine-needle aspiration cytology are rapid, safe, and minimally invasive diagnostic procedures. We report one case of papillary carcinoma in subhyoid ectopic thyroid to emphasise the importance to evaluate all ectopic thyroid tissues.

Carcinoma, Papillary↗

PubMed2004

Biocompatibility of NGF-grafted GTG membranes for peripheral nerve repair using cultured Schwann cells.

We previously developed a biodegradable composite with potentially good biocompatibility composed by tricalcium phosphate and gluataraldehyde cross-linking gelatin (GTG) with good mechanical property feasible for surgical manipulation. The purpose of this study was to evaluate the feasibility of immobilizing nerve growth factor (NGF) onto the composite (GTG) with carbodiimide (GEN composite). Cultured Schwann cells were seeded onto the GTG and GEN composites. For comparison, GTG membrane soaked in NGF solution without carbodiimide (GN composite) as cross-linking agent was also used to culture Schwann cells. Cell morphology was observed by a scanning electron microscope. Cell survival, cytotoxicity and cellular metabolism on the NGF-grafted GTG membrane were assessed quantitatively in terms of cell protein content, leakage of cytosolic lactate dehydrogenase (LDH) activity and by the well-established MTT assay, respectively. The result of LDH study did not show significant difference among GTG, NGF-modified GTG and control group. This indicated that GTG composite, whether cross-linking with NGF or not, has little cytotoxic effect. Comparing the protein content and MTT assay among GEN, GN composite and control group, the data confirmed more attachment of Schwann cells on GEN composite. Although GTG cross-linking with NGF did not promote Schwann cell proliferation, the techniques we used in this study provided a method to fabricate a novel biomaterial incorporation of Schwann cells and covalently immobilized NGF.

Animals↗

PubMed2004

A lumbar clear cell meningioma with foraminal extension in a renal transplant recipient.

Spinal meningiomas are characteristically dural based. We report a lumbar clear cell meningioma extending into the intervertebral foramen without dural attachment which mimics a neurilemmoma. This is a rare finding, with no other reported cases in the literature. The importance of recognizing clear cell meningioma relates specifically to its inordinately aggressive clinical course. Compared to with of spinal clear cell meningiomas reported to date, our case showing the extension into the intervertebral foramen and mimicking a neurilemmoma is rather unique. Clear cell meningioma may be confused with other clear cell tumors, especially with the similar-looking metastatic renal cell carcinoma, which should be carefully ruled out in our case - an immunosuppressed renal transplant recipient.

Adult↗

PubMed2004

Cervical subdural empyema following acupuncture.

A review of the literature reveals only a few cases of spinal subdural empyema. Etiologies of spinal subdural empyema include hematogenous spread from skin lesions, systemic sepsis, direct spread from spinal osteomyelitis and complications of discography. However, in this report, we describe a patient who developed spinal subdural empyema following several cervical acupuncture sessions. Operative treatment with adequate laminectomy, removal of abscess, and copious irrigation resulted in good recovery. Microbiologic culture study of pus obtained at surgery was positive for Staphylococcus aureus. The need for sterilization procedures for acupuncture is emphasized and a brief review of the relevant literature is presented.

Acupuncture Therapy↗

PubMed2004

Endoscopic ligation vs. nadolol in the prevention of first variceal bleeding in patients with cirrhosis.

BACKGROUND: The value of band ligation for prevention of the first episode of variceal bleeding has not been fully evaluated. This study compared the efficacy and safety of band ligation vs. treatment with a beta-blocker for the prophylactic prevention of first bleeding in patients with cirrhosis and high-risk esophageal varices. METHODS: A total of 100 patients with cirrhosis and endoscopically determined high-risk esophageal varices but no history of bleeding were randomized to band ligation (50 patients) or treatment with nadolol (50 patients). In the ligation group, two to 4 elastic bands were deployed during each session. Ligation was repeated at intervals of 3 to 4 weeks until variceal obliteration was achieved. In the nadolol group, the dose of the drug, administered once daily, was sufficient to reduce the pulse rate by 25%. RESULTS: In the ligation group, variceal obliteration was achieved in 41 patients (82%), at a mean of 2.7 (1.1) ligation sessions. In the nadolol group, the mean daily dose of nadolol administered was 60 (20) mg. During follow-up (median approximately 22 months), 10 patients (20%) in the ligation group and 16 (32%) in the nadolol group had upper-GI bleeding (p=0.23). Esophageal variceal bleeding occurred in 5 patients (10%) in the ligation group and 9 (18%) in the nadolol group (p=0.31). By multivariate Cox analysis, Child-Pugh class was the only factor predictive of variceal bleeding. Minor complications were noted in 9 patients (18%) in the ligation group and 4 (8%) in the nadolol group (p=0.35). No serious complication was encountered. Twelve patients in the ligation group and 11 in the nadolol group died (p=0.62). One patient in the ligation group and 3 in the nadolol group died from uncontrollable variceal hemorrhage. CONCLUSIONS: Variceal ligation is as effective and as safe as treatment with nadolol for prevention of first variceal bleeding in patients with cirrhosis.

Adult↗

PubMed2004

The characteristics and the prognosis for patients presenting with actively bleeding esophageal varices at endoscopy.

BACKGROUND: It remains unresolved whether the prognosis is worse for patients who present with actively bleeding varices at endoscopy compared with those in whom variceal bleeding has stopped. METHODS: Patients with acute esophageal variceal bleeding were enrolled in this study and were divided into two groups: an active bleeding group and an inactive bleeding group. All patients had band ligation shortly after endoscopic examination and underwent elective ligation procedures until the varices were obliterated. Patients were followed for 1 year or until death. Short- and long-term prognoses were compared. RESULTS: The active bleeding group included 54 patients and the inactive bleeding included 251 patients. Initial hemostasis was achieved in 93% in the active group and 99% in the inactive group ( p = not significant). The rate of recurrent variceal bleeding within 30 days was 24% in the active bleeding group vs. 12% in the inactive bleeding group ( p = 0.01); the mortality rates were 18% and 8%, respectively ( p = 0.03 in a single statistical test; however, Bonferroni correction for the multiple testing of data removed this significance). The rate of recurrent variceal bleeding within 1 year was 37% in the active bleeding group and 27% in the inactive bleeding group ( p = 0.06); the mortality rates were 22% and 21%, respectively ( p = not significant). CONCLUSIONS: Whether variceal bleeding is active or inactive at endoscopy, variceal ligation is equally effective for control of bleeding. The rates of recurrent bleeding and mortality at 1 month were significantly higher among patients with active bleeding. However, the mortality rate was similar for both groups at 1 year.

Endoscopy, Gastrointestinal↗

PubMed2003

Factors affecting long-term survival of Taiwanese patients with medullary thyroid carcinoma.

BACKGROUND AND PURPOSE: Long-term survival of patients with postoperative recurrence of medullary thyroid carcinoma (MTC) is not uncommon. This study assessed whether local or distant recurrence after operation is a significant factor affecting long-term survival in Taiwanese patients with MTC. The benefit of family screening for MTC patients on survival was also evaluated. METHODS: A total of 54 patients with a diagnosis of MTC by pathology or cytology during the period from 1977 to 2000 were included in the study. Survival curves were compared between different groups according to age, gender, tumor size, metastasis, recurrence after surgical intervention, or diagnosis before and after the performance of family screening for MTC patients. RESULTS: The 5-year survival rate using the Kaplan-Meier method was 84.1% (95% confidence interval, 73.9% to 94.2%), and the 10-year survival rate was 77.6% (95% confidence interval, 64.9% to 90.3%). Patients with lymph node metastasis and distant metastasis before operation had significantly shorter survival. Surprisingly, recurrence was not associated with shorter survival. Patients diagnosed after the start of family screening in 1991 had fewer lymph node metastases before operation, and lived longer. CONCLUSIONS: Patients with lymph node or distant metastasis before operation had poor prognosis. However, local or distant recurrence after operation did not influence survival. Efforts to obtain early diagnosis and surgical intervention before tumor metastasis, such as family screening, resulted in improved survival.

Adolescent↗

PubMed2002

Banding ligation versus nadolol and isosorbide mononitrate for the prevention of esophageal variceal rebleeding.

BACKGROUND & AIMS: beta-blockers and banding ligation are effective in the prevention of variceal rebleeding. However, the relative efficacy and safety remains unresolved. METHODS: One hundred twenty-one patients with a history of esophageal variceal bleeding were enrolled. Patients were randomized to undergo regular endoscopic variceal ligation (EVL group, 60 patients) until variceal obliteration, or drug therapy by using nadolol plus isosorbide mononitrate (N+I group, 61 patients) during the study period to prevent rebleeding. RESULTS: After a median follow-up period of 25 months, recurrent upper gastrointestinal bleeding developed in 23 patients in the EVL group and 35 patients in the N+I group (P = 0.10). Recurrent bleeding from esophageal varices occurred in 12 patients (20%) in the EVL group and 26 patients (42%) in the N+I group (relative risk = 0.45; 95% confidence interval, 0.24-0.85). The actuarial probability of rebleeding from esophageal varices was lower in the EVL group (P = 0.01). The multivariate Cox analysis indicated that the treatment was the only factor predictive of rebleeding. Treatment failure occurred in 8 patients (13%) in the EVL group and 17 patients (28%) in the N+I group (P = 0.01). Fifteen patients in the EVL group and 8 patients of the N+I group died (P = 0.06). Complications occurred in 17% of the EVL group and in 19% of the N+I group (P = 0.6). CONCLUSIONS: Our trial showed that ligation was more effective than nadolol plus isosorbide-5-mononitrate in the prevention of variceal rebleeding, with similar complications in both treatment modalities. However, there is no significant difference in the survival rate between the 2 groups.

Adult↗