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Biomedical subjects

J T Chen

Publications and source records attributed to J T Chen.

At least 91 records · Page 5Linked to original sources
PubMed1998

Conditioning effect on the long latency potentials in the lower limb to transcranial magnetic stimulation.

OBJECTIVES: We used an electrical conditioning stimulation followed by transcranial magnetic stimulation (TMS) to facilitate the occurrence of long latency potentials (LLPs) in order to study the relationship between primary motor evoked potentials (MEPs) and LLPs in the lower limbs. MATERIALS AND METHODS: The study group included 6 healthy subjects, 1 patient with right thalamic infarction, and 3 patients with spinal cord injuries. The subjects were subjected to electrical conditioning (C) stimulation delivered to the left big toe at 250 Hz in a train of pulses of 20 ms duration prior to TMS (T) from 0 to 150 ms at an increment of 10 ms. The surface electromyographic signals were recorded at the tibialis anterior and gastrocnemius medialis for 400 ms. RESULTS: The C-T test facilitated both primary MEPs and LLPs with a pattern similar to the primary MEPs of its antagonist. There was no facilitation of the primary MEPs or LLPs in the affected limb of patients with thalamic or spinal cord lesions. CONCLUSION: At appropriate C-T interval, LLPs could be consistently provoked by TMS. The LLPs were absent in the patients with thalamic infarction and spinal cord injuries. It suggests that LLPs might be provoked through a supraspinal control.

Adult↗
PubMed1998

Long latency responses in pure sensory stroke due to thalamic infarction.

OBJECTIVES: Our study was designed to clarify the role of the thalamus in the generation of the electrically elicited long-latency reflexes (LLR) in voluntarily activated hand muscles. MATERIALS AND METHODS: EMG responses of the thenar muscles were evoked by electrical stimulation of the median nerve at the wrist at motor threshold intensity in 10 patients with acute pure sensory stroke due to thalamic infarction. Concomitant recording of somatosensory evoked potentials (SEPs) was performed. The subjects were asked to steadily abduct the thumb at 20-30% of maximal force against a force transducer. Rectified and averaged EMG activities were recorded. RESULTS: The LLR II was missing completely or significantly attenuated in the majority of the patients (9 of 10), of whom 3 also had delayed latency. Abnormal SEPs were documented in 7 patients (7 of 10). In the follow-up, 5 patients had partial reversal of LLR II. LLR II was still pathological in 1 fully recovered patient. CONCLUSION: Our results further confirm the transcortical generation of LLR II and imply that a thalamic relay is present in the afferent limb of the LLR.

Adult↗
PubMed1998

A SPECT study of patients with gait apraxia without evidence of frontal lobe dysfunction.

BACKGROUND: The pathogenesis of gait apraxia (GA) is unknown. Even though imaging studies provide excellent assessment of brain morphology, there is still a lack of congruous results. Single photon emission computed tomography (SPECT) using Tc-99m hexamethylpropyleneamine oxime (HMPAO) may show alterations in regional cerebral blood flow (rCBF) and provide indirect information about brain metabolism. METHODS: We conducted a SPECT study of GA patients and evaluated the related cortical function. rCBF was assessed in 16 GA patients (15 male, one female; age range 65-79 years, mean 70.5 years) by SPECT using HMPAO. Mean HMPAO cortical or basal ganglia/cerebellum activity ratios were calculated. The regions of interest included the frontal lobe, parietal lobe and basal ganglia. A battery of GA tests and magnetic resonance imaging (MRI) of the brain were also performed in these 16 patients. RESULTS: Nine of the patients had equilibrium disorder, and all 16 patients had locomotion disorder. The MRI findings were lacunar infarct (16/16 in basal ganglia, or 6/16 in thalamus), leukoaraiosis (4/16), enlarged ventricle (3/16), frontal lesion (3/16) and parietal lesion (1/16). Lower rCBF was noted in the frontal lobe (3/16), occipital lobe (1/16, thalamus (7/16) and basal ganglia (9/16). Though SPECT showed decreased rCBF in nine patients (9/16), mean cortical and basal ganglia regional uptake ratios in the patient group were not significantly different from values in the control group (cortical p = 0.0613; basal ganglia p = 0.0576, by Student's t-test). CONCLUSIONS: Though only a small number of patients were studied, it was clear that brain SPECT and MRI did not show any significant abnormalities in the frontal or parietal lobes of patients with GA. Thus, the pathogenesis of GA and its related anatomic lesion should be further investigated.

Aged↗
PubMed1998

Tumor angiogenesis and metastasis: correlation in invasive renal cell carcinoma.

BACKGROUND: Experience suggests that tumor growth is dependent on angiogenesis. The intensity of angiogenesis in human cancer is reported to be predictive of the probability of metastasis in many types of cancer. The aims of this study were 1) to determine the relationship of microvessel density (MVD) in renal cell carcinoma to pathologic stage, and 2) to evaluate the role of MVD in metastasis. METHODS: Paraffin-embedded tumor specimens were reviewed from 34 unselected patients with RCC who had undergone surgery from 1986 to 1990 at Taichung Veterans General Hospital. The pathology findings and clinical records were reviewed to note relationships between pathologic stage and whether or not metastasis had occurred. Specimens were studied from 16 cases (eight Stage I cancers, five Stage II and three Stage III) without metastasis and from 18 cases (two Stage I, six Stage II, six Stage III and four Stage IV) in which metastasis later developed. Microvessels were highlighted by immunostaining endothelial cells for factor VIII-related antigen. Microvessels were counted in a x-400 field (0.1885 mm2/field) in the most active areas of neovascularization. RESULTS: The 16 patients without metastasis have survived for between 65 and 136 months (mean, 94.5 months), up to the present time. Of the 18 patients with metastasis, 15 died and three survived, with mean survivals of 42.8 months (range, 12-99 months). Mean overall MVD was 99.6 vessels; mean MVD was 98.5, 96.2, 109.3 and 90.0 in Stages I, II, III and IV tumors, respectively. Mean MVD was 99.3 in patients without metastasis and 99.9 in patients with metastasis. CONCLUSIONS: MVD does not correlate with pathologic stage and is of no prognostic significance in renal cell carcinoma.

Adult↗
PubMed1998

Intratumoral injection of rhenium-188 microspheres into an animal model of hepatoma.

UNLABELLED: Intratumoral injection of 90Y microspheres is a potential alternative in the treatment of primary liver tumor. However, complicated preparation and lack of a gamma ray for imaging are the disadvantages of 90Y. In this study, we used 188Re, a generator-produced radioisotope with 155-keV gamma ray emission, to label microspheres. After intratumoral injection of 188Re microspheres into rats with hepatoma, biodistributions and survival times were analyzed. METHODS: Twelve male rats with hepatoma were killed at 1, 24 and 48 hr (4 rats at each time point) after intratumoral injection of approximately 7.4 MBq 188Re microspheres. Samples of various organs were obtained and used to calculate the tissue concentrations. In addition, 30 male rats bearing hepatoma were divided into two groups (15 rats in each group) to evaluate survival time. Group 1 received intratumoral injection of 37 MBq 188Re microspheres, whereas Group 2 served as the control group and received an intratumoral injection of 0.1 ml normal saline only. Survival time was calculated from the day of injection to 2 mo after treatment. RESULTS: Radioactivity in the tumor was very high throughout. Biological half-time was 170.8 hr. Radioactivity in the lung was 1.78% injected dose (i.d.)/g at 1 hr but declined rapidly over time. The concentration in the urine was approximately 6.14% i.d./ml after the first hour and rapidly declined thereafter. The concentrations of radioactivity in other organs, such as normal liver, muscle, spleen, bone, testis and whole blood, were quite low throughout the study. Twelve of 15 (80%) of rats survived over 60 days after intratumoral injection of 188Re microspheres, whereas only 4 of 15 (26.7%) survived more than 60 days after injection of normal saline only. The difference between the groups was significant (p < 0.05). CONCLUSION: Rhenium-188 offers cost-effectiveness, on-site availability, short half-life, energetic beta particle, emission of gamma photons for imaging, easy preparation, easy clinical administration and apparent lack of radiation leakage from the treated tumor. Direct intratumoral injection of 188Re microspheres is extremely attractive as a clinical therapeutic alternative in hepatoma patients.

Animals↗
PubMed1998

Fine-needle aspiration cytology of retroperitoneal extramedullary hematopoiesis: a case report.

We report a 69 year-old man with left renal hilar tumor, which was incidentally detected and clinically suspected to be malignant. Interpretations of fine-needle aspiration (FNA) and frozen section of this tumor were not conclusive, and originally malignancy could not be ruled out. Later, correlation with the patient's history and bone marrow biopsy with cytological and histological pictures resulted in the diagnosis of a tumor of extramedullary hematopoiesis (EMH). This case shows that FNA cytology may be a useful method for diagnosing EMH. However, we also demonstrate the potential pitfall of misdiagnosing atypical megakaryocytes as malignant cells on FNA smears, or even in frozen sections, when clinical history and clinical data are not available. EMH should be considered in the differential diagnosis of patients with bone marrow disorders and mass lesions in extramedullary sites.

Aged↗
PubMed1997

Referred pain elicited by palpation and by needling of myofascial trigger points: a comparison.

OBJECTIVE: To investigate the occurrence of referred pain (ReP) elicited by palpation (Pal-ReP) or by needle injection (Inj-ReP) of myofascial trigger point (MTrP), and to assess the correlated factors, including the pain intensity of an active MTrP and the occurrence of local twitch response (LTR). DESIGN: Correlational study. PATIENTS: Ninety-five patients who were treated with MTrP injections. INTERVENTION: MTrP injections. MAIN OUTCOME MEASURE: Pain intensity of MTrP and occurrence of Pal-ReP, Inj-ReP, and LTR. RESULTS: Both Pal-ReP and Inj-ReP were elicited in 53.9% of MTrPs, Inj-ReP, but not Pal-ReP, was elicited in 33.7% of MTrPs. Both Pal-ReP and Inj-ReP were unobtainable in 12.3% of MTrPs. The occurrence of ReP was significantly correlated to the pain intensity of active MTrP and the occurrence of LTR. CONCLUSION: ReP could be elicited more frequently by needling than by palpation. The frequency of occurrence in ReP mainly depends on pain intensity of an active MTrP.

Adult↗
PubMed1997

1-alpha-Hydroxyvitamin D3 treatment decreases bone turnover and modulates calcium-regulating hormones in early postmenopausal women.

50 Japanese women within 10 years after menopause (mean age 52.5 years) were studied to determine the effects of 0.75 microgram of 1-alpha-hydroxyvitamin D3 [1-alpha-(OH)D3] with calcium (150 mg/day) (treated group: N = 25) and calcium only (control group: N = 25) for 12 months on bone mass and metabolism. Their L2-4 BMD measurements were 1.5 SD below the mean value of Japanese young, normal women. L2-4 BMDs increased significantly in the treated group (+2.1%; p < 0.01), but decreased significantly in controls (-2.1%; p < 0.01). Although serum calcium and creatinine remained unchanged in both groups, phosphorus levels increased significantly in the treated group (p < 0.01). Urinary calcium/creatinine (Cr) increased in both groups. Urinary pyridinoline/Cr and deoxypyridinoline/Cr decreased significantly in the treated group (p < 0.05), but not in the control group. Serum osteocalcin levels remained unchanged in both groups. Intact parathyroid hormone levels decreased significantly (p < 0.05) and calcitonin levels significantly increased in the treated group (p < 0.05), but these changes were not observed in the control group. These data clearly demonstrate that 0.75 microgram of 1-alpha-(OH)D3 maintained bone mass by reducing bone resorption by modulation of calcium-regulating hormones. Temporarily increased urinary calcium excretion was observed in control group, but did not appear to be effective in modulating bone turnover.

Biomarkers↗
PubMed1997

Primary coexistent adenocarcinoma and choriocarcinoma of the stomach. A case report and review of the literature.

We report a case of primary gastric choriocarcinoma with liver metastasis. The mixed histologic patterns included adenocarcinoma, undifferentiated carcinoma, and choriocarcinoma. Immunohistologic staining for the beta-subunit of human chorionic gonadotrophin (beta-HCG) showed positive results in the choriocarcinoma, adenocarcinoma, and normal mucosal gland. However, positive HCG cells were present at different intensities in the choriocarcinoma, adenocarcinoma, and normal mucosal gland. The level of HCG was significantly increased in serum. This unusual tumor probably resulted from dedifferentiation of a primary adenocarcinoma or developed directly from the mucosal glands.

Adenocarcinoma↗
PubMed1997

Mutational analysis of BRCA1 gene in ovarian and breast-ovarian cancer families in Japan.

We analyzed the alteration of BRCA1 in DNA obtained from 83 individuals of 13 Japanese site-specific ovarian cancer families and 6 breast-ovarian cancer families. Six germline mutations were detected in 7 families, which consisted of 4 breast-ovarian cancer and 3 site-specific ovarian cancer families, by single-strand conformation polymorphism analysis, followed by direct sequence determination. The mutations included three frameshifts, two nonsense mutations, and one missense mutation causing loss of a zinc-binding motif. The frequency of loss of heterozygosity at the microsatellite markers on the BRCA1 gene was 57% (8 of 14 cases) in site-specific ovarian cancer families, and 100% (6 of 6 cases) in breast-ovarian cancer families. All tumors of the patients carrying a mutation of BRCA1 showed deletion of wild-type alleles, implicating BRCA1 as a tumor suppressor gene. These results suggest that germline mutations of the BRCA1 gene play an important role in the carcinogenesis of breast and/or ovarian cancer in a majority of breast-ovarian cancer families and in some site-specific ovarian cancer families.

Adult↗
PubMed1997

Thoracic aortic aneurysm repair with endovascular stent-grafts.

The purpose of the study was to describe the clinical experience is using endoluminal stent-grafts for the treatment of thoracic aortic aneurysms in high-risk patients. Patients with aneurysms of the descending thoracic aorta who were considered high surgical risks underwent evaluation for endoluminal repair. The prosthesis was constructed from Z stents covered with polyester fabric using dimensions based upon preprocedural computed tomography scans and angiography. Through a femoral arteriotomy or left retroperitoneal flank incision, a 22-24 Fr delivery catheter was inserted and advanced through the aorta to the target site under fluoroscopic guidance in the operating suite. The stent-graft prosthesis was deployed at the site of the aneurysm. 44 patients (36 male, 8 female; mean age 36 years) underwent stent-graft repair for thoracic aneurysms (mean diameter 6.3 cm). The deployment was technically successful in all cases, with complete aneurysm thrombosis in 88%. The 30-day perioperative mortality rate was 6.8% and 35-month actuarial survival was 82%. There were no cases of stent migration, surgical conversion or intraprocedural death. Paraplegia occurred in two patients who underwent simultaneous surgical infrarenal aortic aneurysm repair immediately followed by stent-graft placement for a coexisting thoracic aneurysm. The conclusion was that placement of endoluminal stent-grafts for repair of thoracic aortic aneurysms is technically feasible in high-risk patients in whom conventional surgery is contraindicated. Long-term studies are needed to determine protection against aneurysm rupture and patient survival.

Adult↗
PubMed1997

Effect of 1 alpha-hydroxyvitamin D3 on loss of bone mineral density immediately after artificial menopause.

To evaluate the effects of 1 alpha-hydroxyvitamin D3 (1 alpha(OH)D3), a series of clinical trials, preventive and therapeutic, were performed in an open label manner in women immediately after oophorectomy. The series included a total of 121 oophorectomized subjects, whose lumbar bone mineral density (L2-4BMD) was followed by the use of dual energy X-ray absorptiometry. (1) Preventive trial: 61 women who had undergone premenopausal bilateral oophorectomy, were divided into 3 groups (Group C: control; Group L: 0.25 micrograms 1 alpha (OH)D3/day; Group H: 0.50-0.75 micrograms 1 alpha (OH)D3/day). The changes in BMD and chemical indices were followed up for one year. (2) Therapeutic trial: the trial included 60 premenopausally oophorectomized subjects having L2-4BMD lower than the normal control level minus 1SD which has been reported in age-matched normal Japanese women. These subjects were divided into 3 groups and treated in the same way as in the preventive trial. In the preventive trial, L2-4BMD decreased by 8.2%, 6.5% and 4.5% in groups C, L and H, respectively, at 12 months of treatment, whereas in the therapeutic trial, L2-4BMD decreased by 3.6%, 3.2% and 0.8% in the groups C, L and H, respectively, at 12 months of treatment. In conclusion, 1 alpha(OH)D3 was found to be effective both to prevent the bone loss subsequent to bilateral oophorectomy and improve low bone mass after oophorectomy.

Bone Density↗
PubMed1997

Optimal surgical strategy for potentially curable serosa-involved gastric carcinoma with intraperitoneal free cancer cells.

BACKGROUND: Radical gastrectomy with systematic lymphadenectomy (RG) remains controversial in the treatment of gastric carcinoma. On the other hand, the prognosis of gastric carcinoma, in the presence of intraperitoneal free cancer cells, is poor. The optimal surgical strategy for serosa-involved gastric carcinoma with intraperitoneal free cancer cells remains undefined. STUDY DESIGN: A prospective study of intraperitoneal cytologic washing was conducted on 134 patients with potentially curable serosa-involved gastric carcinoma who underwent RG. During the same period, 28 patients with resectable tumors who received palliative simple gastrectomies because of the presence of gross incurable conditions (eg, multiple hepatic metastases, peritoneal carcinomatosis, or extra-abdominal metastasis) were used as controls. RESULTS: Intraperitoneal free cancer cells were found in 26 patients (19.4 percent). Compared with the remaining 108 patients without free cancer cells, there were no significant differences in the clinicopathologic characteristics and pathologic stages. No patients died after palliative resection, but five patients died after RG. The patients with free intraperitoneal free cancer cells had a poorer long-term prognosis after RG than those without free cancer cells (p < 0.0001). The prognosis for such patients was similar to the prognosis of those who underwent palliative resection. CONCLUSIONS: A peritoneal washing cytologic examination is mandatory before resection for potentially curable serosa-involved gastric carcinoma. When free cancer cells appear in the washing fluid, the cancer is incurable. Simply gastrectomy without additional lymphadenectomy is the optimal strategy for treatment.

Aged↗
PubMed1997

Frozen-section diagnosis in surgical pathology: a quality assurance study.

In a quality assurance study we reviewed one thousand four hundred and forty-three consecutive frozen sections performed at department of pathology, VGH-TC from June 1995 to July 1996. The diagnostic accuracy was 92.6%. The diagnosis was deferred in sixty-eight cases (4.7%). False positive for malignant tumor was made in two cases (0.14%) and false negative diagnosis for malignancy in thirty-seven (2.56%). The inaccurate diagnosis was mainly in samples taken from the brain, female breast, and thyroid. Incorrect diagnoses were mainly due to interpretation of the pathologic findings (71.8%), followed by gross sampling (15.4%) and microscopic sampling (12.8 %). Some of the lesions were difficult to diagnose even in permanent sections. Technical skill and diagnostic expertise are essential for frozen diagnosis. We suggest that an accuracy survey of frozen section be periodically performed in every pathology department as part of its quality assurance program.

Animals↗
PubMed1997

Prediction of bleeding diathesis in patients undergoing cardiopulmonary bypass during cardiac surgery: viscoelastic measures versus routine coagulation test.

BACKGROUND: Severe hemorrhagic tendency often complicates cardiopulmonary bypass (CPB) in cardiac surgery. In this study, we compared the effectiveness of thromboelastography (TEG), Sonoclot (SCT), and routine coagulation test (RCT) in the prediction of coagulation defects. METHODS: Forty-three patients undergoing cardiac surgery with CPB were included. Blood for RCT, TEG, and SCT profiles was sampled before systemic heparinization and after protamine administration. Clinically significant bleeding was defined as chest tube drainage in excess of 100 ml/h for 3 consecutive hours or 300 ml/h in 1 h. All coagulation parameters obtained before and after CPB were compared. The sensitivity, specificity, accuracy, false positive, and false negative rate were also calculated and compared. RESULTS: All coagulation tests were within normal range except higher partial thromboplastin time. Variables which were significantly different from those before CPB included platelet count, fibrinogen level, prothrombin time, and thrombin time in RCT, alpha angle and maximum amplitude in TEG, and R2 and peak time in SCT. In the TEG tracing, all variables had high sensitivity, specificity, and accuracy (average 85.4%, 83%, and 83.5% respectively) and low false positive and negative rate (12.5% and 5% respectively). Although SCT had high sensitivity (76.3%) and low false negative rate (6.5%), its specificity and accuracy were all under 50%. CONCLUSIONS: Our data demonstrated that the TEG monitoring is a useful tool for detecting post-CPB bleeding diathesis and can provide much predictive information. RCT and SCT are of limited value because of higher rate of unreliable results.

Blood Coagulation Tests↗
PubMed1996

Serum N-terminal osteocalcin is a good indicator for estimating responders to hormone replacement therapy in postmenopausal women.

To estimate the response to hormone replacement therapy (HRT) by bone metabolic markers, 36 patients with postmenopausal osteoporosis or osteopenia were studied to assess the correlation between percent baseline changes in lumbar bone mineral density (BMD) after 12 months and those in various bone metabolic markers after 3, 6, and 12 months of HRT. All the patients were treated with 0.625 mg of conjugated estrogen and 2.5 mg of medroxyprogesterone per day and continued for 12 months. BMD was significantly increased up to 4.19 +/- 0.87% after 6 months and 4.93 +/- 1.27% after 12 months of HRT (p = 0.0001 by analysis of variance). In accordance with this, changes in the levels of osteocalcin (p = 0.041), alkaline phosphatase (p = 0.0001), N-terminal osteocalcin (p = 0.0001), urinary excretion of pyridinoline/Cr (p = 0.0001), and deoxypyridinoline/Cr (p = 0.0001) were significantly decreased, respectively. Among these bone metabolic markers, only the change in the serum N-terminal osteocalcin at 3 months (r = 0.557, p = 0.0022), at 6 months (r = 0.470, p = 0.0184), and at 12 months (r = 0.545, p = 0.0061) significantly correlated with the change in BMD 12 months after HRT. The elution profiles of immunoreactive osteocalcin-related molecules in serum fractionated by reverse-phase high performance liquid chromatography revealed that the N-terminal fragment as well as the intact osteocalcin molecule decreased after 3 months of HRT. These results demonstrate that N-terminal osteocalcin is a suitable predictor for estimating good responders to HRT in postmenopausal women.

Analysis of Variance↗
PubMed1996

Overexpression of p53 is not a feature of ovarian granulosa cell tumors.

The p53 tumor suppressor gene has been extensively studied in various human tumors including epithelial ovarian cancers. However, little is known about the expression of this gene in ovarian granulosa cell tumors, the most common histologic type of sex cord-stromal tumors. We investigated whether overexpression of the p53 gene product occurs in this specific ovarian tumor. Nineteen patients with ovarian granulosa cell tumors were recruited in this study. Immunohistochemical staining for the p53 protein with monoclonal antibody PAb 1801 was performed in the paraffin-embedded tissue of each case to screen for p53 overexpression. Among the 19 ovarian granulosa cell tumors, there was only one well-differentiated tumor found to have nuclear immunoreactivity in a small fraction of tumor cells. Polymerase chain reaction--single-stranded conformation polymorphism was used to study the tumor showing focal p53 positivity, but no mobility shift was noted from exon 4 through exon 9 of the p53 gene. On the basis of this observation, we propose that alteration of the p53 tumor suppressor gene is not a common finding in ovarian granulosa cell tumors.

Adolescent↗