Biomedical subjects

T C Chang

Publications and source records attributed to T C Chang.

At least 55 records · Page 3Linked to original sources

PubMed1999

Preoperative prognostic variables and the impact of postoperative adjuvant therapy on the outcomes of Stage IB or II cervical carcinoma patients with or without pelvic lymph node metastases: an analysis of 891 cases.

BACKGROUND: The purpose of this study was to investigate pretreatment variables that could predict prognosis and to evaluate the impact of postoperative adjuvant therapy on the outcomes of patients with Stage IB or II cervical carcinoma with or without pelvic lymph node metastases. METHODS: Eight hundred ninety-one patients with Stage IB or II cervical carcinoma who underwent radical hysterectomy and bilateral pelvic lymphadenectomy as primary treatment at a single institution were analyzed. Potential prognostic variables were studied. RESULTS: Among the variables that could be assessed before treatment, depth of cervical stromal invasion (determined by magnetic resonance imaging), clinical stage, tumor size, grade of differentiation, and DNA index (determined by flow cytometry) were independent predictors of outcome in multivariate analysis using a Cox regression model. Three distinct prognostic groups (low, intermediate, and high risk) were defined using these variables. Five-year recurrence free survival (RFS) rates for the low, intermediate, and high risk groups were 94.6%, 82.7%, and 62.3%, respectively (P = 0.0001), and overall survival (OS) rates were 98.4%, 84.5%, and 68.7%, respectively (P = 0.0001). Among patients with pelvic lymph node metastases who were free of parametrial extension, those who received postoperative chemotherapy or chemoradiotherapy had significantly better RFS (P = 0.017) and OS (P = 0.043) than those who received no adjuvant therapy. Among patients without pelvic lymph node metastases but at high risk of recurrence, those who received adjuvant radiotherapy had significantly better RFS (P = 0.015) and marginally improved OS (P = 0.087) compared with those who received no adjuvant therapy. CONCLUSIONS: A model containing assessable pretreatment variables for predicting the prognoses of patients with early stage cervical carcinoma was formulated. Subsets of patients for whom postoperative chemotherapy or radiotherapy might be beneficial were identified. The data from this retrospective review may be useful when future prospective trials of the treatment of early stage cervical carcinoma are designed.

Adult↗

PubMed1999

A study of diagnostic failure of loop conization in microinvasive carcinoma of the cervix.

OBJECTIVE: The aim of this study was to evaluate the specimen adequacy and the histological interpretation of loop conization for microinvasive cervical carcinoma. METHODS: We retrospectively reviewed the histopathological findings of the original cone specimens together with the final hysterectomy specimens in patients with microinvasive carcinoma of the cervix. From 1990 to 1995, 63 consecutive patients with microinvasive carcinoma of the cervix were included in the study, of which 35 patients underwent loop conization and 28 underwent cold-knife conization. All patients had a hysterectomy. RESULTS: The mean width, depth, and cone volume of the conization specimens were 2.44 cm, 2.15 cm, and 3.96 cm3, respectively, in the loop group versus 2.3 cm, 2.35 cm, and 4.38 cm3 in the cold-knife group. No significant differences were seen between the two groups. The application of loop conization was completed in a single slice in 27 patients (77.1%) and multiple slices by the loop in 8 (22.9%), in spite of the attempt to perform conization in a one-pass application when possible. In assessing these cone specimens microscopically, the rate of transection of tissue was significantly higher in the loop cone than in the cold-knife cone (17.1% versus 0%, P = 0.02). Because of transection of tissue and misorientation, pathologic determination of the depth and width of stromal invasion was undetermined in two loop cone specimens compared with none in the cold-knife cones. CONCLUSION: Our study suggests that cold-knife conization is a preferred method in assessing microinvasive carcinoma of the cervix if multiple applications of loop conization are inevitable.

Adult↗

PubMed1999

Prognostic factors and treatment for placental site trophoblastic tumor-report of 3 cases and analysis of 88 cases.

OBJECTIVE: In order to understand the prognostic factors of placental site trophoblastic tumors (PSTT), we performed a MEDLINE search for cases from 1976 through 1998 and report three cases. MATERIALS AND METHODS: The patients' age at presentation, antecedent pregnancies, and responses to treatment were analyzed according to the extent of disease, disease status after treatment, and survival in 88 cases. RESULTS: Patients with disease extending outside the uterus at presentation had a median latency of 24 months between the antecedent pregnancy and presentation of PSTT, which was significantly longer than that of 12 months in those with disease confined to the uterus. Patients with metastatic diseases were 3 years older than patients with diseases confined to the uterus and had a higher incidence of term delivery as their antecedent pregnancy. The outcomes of patients with FIGO stage I-II disease after hysterectomy were excellent, while those with FIGO stage III-IV diseases had a 30% survival. Although initial partial responses to chemotherapy were observed in some patients, only 5 patients achieved a complete remission and 3 of these 5 received a combination of etoposide, methotrexate, and actinomycin-D, alternating with cyclophosphamide and vincristine. CONCLUSION: FIGO stage is the most important prognostic factor, and complete removal of all lesions provided good outcomes in PSTT patients. For those with unresectable tumors, combination chemotherapy showed a high response rate, but only a few achieved a complete response.

Adult↗

PubMed1999

The prognostic factors for patients with early cervical cancer treated by radical hysterectomy and postoperative radiotherapy.

PURPOSE: This study was undertaken to evaluate the efficacy of postoperative radiotherapy (post-OP RT) and to investigate the prognostic factors for early-stage cervical cancer patients who were treated by radical surgery, and the pathological findings suggested a relatively high risk of relapse with surgery alone. MATERIALS AND METHODS: From January 1990 to December 1995, 222 patients with stage IB-IIA cervical cancer, treated by radical surgery and a full course of post-OP RT, were included in this study. The indications for post-OP RT were based on pathological findings, including lymph node metastasis, positive surgical margins, parametrial extension, lymphovascular permeation, and invasion of more than two-thirds of the cervical wall thickness. The radiation dose of external beam was 44-45 Gy to the whole pelvis and 50-54 Gy to the true pelvis. One hundred seventy-two patients also received intravaginal brachytherapy as a local boost. The minimal follow-up period was 2 years. RESULTS: The actuarial 5-year overall and disease-specific survival rates for all patients were 76 and 82%, respectively. The tumor control rate within the pelvis reached 94%, and distant metastasis was the major cause of treatment failure. Univariate analysis of clinical and pathological parameters revealed that clinical stage, bulky tumor size, positive lymph nodes, parametrial extension, and histologic type were significant prognostic factors. After multivariate analysis, only positive lymph nodes (P = 0.01), bulky tumor size (P = 0.02), and parametrial extension (P = 0.05) independently influenced the disease-specific survival (DSS). For patients with lymph node metastasis, the number and location of the nodal involvement significantly affected the prognosis. The 5-year DSS for patients with no, one, and more than one lymph node metastasis were 87, 84, and 61% (P = 0.0001), respectively. Patients with upper pelvic lymph node metastasis had a higher incidence of distant metastasis (50% vs 16% in lower pelvic node group, P = 0.03). In the subgroup of single lower pelvic nodal metastasis, the prognosis was similar to that of patients without lymph node involvement (5-year DSS 85% vs 87%, P = 0.71). CONCLUSION: Our results indicate that post-OP RT can achieve very good local control in stage IB-IIA cervical cancer patients whose pathological findings show risk features for relapse after radical surgery. The prognostic factors for treatment failure identified in this study can be used as selection criteria for clinical trials to test the effects of other adjuvant treatments, such as chemotherapy. Patients with a single lower pelvic lymph node metastasis have a relatively good prognosis and may not need adjuvant treatment beyond radiation therapy.

Adult↗

PubMed1999

Demonstration of thyrotropin receptor mRNA in orbital fat and eye muscle tissues from patients with Graves' ophthalmopathy by in situ hybridization.

There is a controversy regarding whether there are thyrotropin (TSH) receptors in orbital fat and eye muscle tissues that may play a role in the pathogenesis of Graves' ophthalmopathy. To elucidate whether there are TSH receptors in orbital fat and eye muscle tissues in patients with Graves' ophthalmopathy, we applied the method of in situ hybridization in orbital fat and eye muscle tissues obtained during the operation for patients with Graves' ophthalmopathy, to directly detect TSH receptor mRNA. To identify whether the cells with positive TSH receptor mRNA are fibroblasts, we also did vimentin immunoreactivity study. To further prove the transcript does have a full length of TSH receptor, the samples of total RNA preparations, extracted from orbital fat and eye muscle tissues, were used as a template for reverse transcriptase polymerase chain reaction (RT-PCR) using three primer sets to generate cDNA fragments and cloned for sequencing. The results showed that the expression of TSH receptor mRNA was demonstrated in adipocytes and fibroblasts of orbital fat, and perimysial fibroblasts within eye muscle tissues by in situ hybridization and vimentin immunoreactivity study. Also, by using the RT-PCR, cloning and sequencing, we further proved that the transcript does have a full length of TSH receptor. The present study suggested that there are TSH receptors expressed in orbital fat and eye muscle tissues.

Adipocytes↗

PubMed1999

The neurodevelopmental outcome of term infants with different intrauterine growth characteristics.

The objective of this study was to test the hypothesis that neurodevelopmental outcome would differ between two groups of small-for-gestational age infants born at term showing different in utero growth characteristics during the third trimester. The design was a prospective cohort study done at a tertiary referral centre. The 76 subjects who fulfilled the inclusion criteria had an estimated fetal weight below the 10th centile for their gestation. Subsequent to enrolment, repeat ultrasound scans were performed weekly to determine growth velocity. Twenty-three infants whose change in fetal abdominal circumference between first and last scan was greater than -1.5 standard deviation scores (SDS) were assigned to the intrauterine growth retardation group (IUGR) while 53 infants whose fetal abdominal circumference changed less than 1.5 SDS were assigned to the small-for-gestational-age (SGA) group. Ten infants with normal intrauterine growth were enrolled as controls. Following delivery all infants had a neurological examination and a cranial ultrasound scan. At 1 year, 75 infants (87%) were traced and reassessed (49 SGA, 18 IUGR and eight controls) with a neurological examination and a developmental assessment. At birth, impairments were found in 27 (51%) of the SGA, 13 (57%) of the IUGR groups and one (10%) of the controls. At 1 year, 18 (37%) of the SGA subjects, six (33%) of the IUGR subjects and one (13%) of the control infant were impaired, including three (6%) of the SGA subjects and one (6%) of the IUGR subjects who were disabled. We conclude that in term fetuses with an estimated birthweight below the 10th centile for their gestation, the pattern of growth in the third trimester does not affect outcome at 1 year. In spite of optimum obstetric management, nearly one-third of the combined SGA and IUGR term fetuses had suffered some, albeit minor, neurological damage.

Apgar Score↗

PubMed1999

Phase II trial of neoadjuvant chemotherapy in early-stage small cell cervical cancer.

Clinical complete response (CR) to chemotherapy is not uncommon in small cell carcinoma. To understand its pathologic response, we conducted a phase II trial with neoadjuvant chemotherapy followed by hysterectomy in patients with small cell cervical cancer and reviewed all reported cases receiving neoadjuvant chemotherapy followed by hysterectomy through a MEDLINE search. From December 1993 to December 1997, the enrolled patients were treated with two to three courses of vincristine, adriamycin and cyclophosphamide alternating with cisplatin and etoposide (VAC/PE) before hysterectomy. Another three courses of chemotherapy were added after surgery. A total of seven patients was enrolled. Clinical CR was observed in six patients, but microscopic residual tumor was present in all. Lymphatic permeation, scattered residual tumor clusters and residual superficial invasive adenocarcinoma over the cervix presented in five cases, and another had a metastatic pelvic node with no residual cervical tumor. Three of these seven patients have been alive with no evidence of disease for 16.2, 45.2 and 56.6 months, respectively. The other four died from disease 10.3-23.6 months after diagnosis. These findings indicate the discrepancy between clinical and pathologic responses in small cell cervical cancer after chemotherapy and emphasize the necessity of local treatment.

Adult↗

PubMed1999

A case of extraadrenal pheochromocytoma associated with adrenal cortical nodular hyperplasia and papillary thyroid carcinoma.

A 64-year-old woman was admitted in November, 1996 for fluctuating blood pressure. There was multinodular goiter in her neck. High urine VMA and serum aldosterone were noted. Computed tomography showed an oval lesion in the left adrenal gland. Left adrenalectomy was performed and the pathology was proved to be adrenal cortical nodular hyperplasia. Fluctuating blood pressure and high urine VMA persisted after the operation. CT scan of the abdomen revealed a soft tissue mass in lower abdomen. The patient was admitted again in September, 1997. Laboratory examinations showed normal serum aldosterone, normal plasma renin activity and high urine VMA. Aspiration cytology of the thyroid gland disclosed papillary thyroid carcinoma. [131I]-metaiodobenzylguanidine image revealed a high uptake lesion in the right L-3 paravertebral area. Tumor excision and thyroidectomy were performed. The pathology was reported as extraadrenal pheochromocytoma and papillary thyroid carcinoma. Papillary thyroid carcinoma is rarely associated with pheochromocytoma. To our knowledge, this paper is the first report of a patient with extraadrenal pheochromocytoma associated with papillary thyroid carcinoma and adrenal cortical nodular hyperplasia.

Adrenal Cortex↗

PubMed1999

Adrenal cancer with hypertension but low plasma renin and aldosterone.

Patients with malignant lesions of the adrenal gland may present with a syndrome of excess mineralocorticoids. Both primary hyperaldosteronism and excess mineralocorticoids other than aldosterone resulting from adrenal carcinoma have rarely been reported. In most patients with adrenal tumors secreting mineralocorticoids other than aldosterone, distant metastasis had already occurred at the time of diagnosis and the prognosis was poor. We present a rare case of adrenal cancer with hypertension in a patient with low plasma renin activity and a low plasma aldosterone concentration. The patient's blood pressure returned to normal after removal of the tumor. The patient is still alive and without recurrence 6 years after surgery. This case illustrates the value of thorough evaluation of hypertension and prompt surgical treatment for patients with adrenal cancer.

Adrenal Cortex Neoplasms↗

PubMed1999

Combination of color Doppler ultrasonography and ultrasound-guided fine-needle aspiration cytology for localization of parathyroid lesions.

We examined the usefulness of color Doppler ultrasonography combined with ultrasound-guided fine-needle aspiration cytology (FNAC) for preoperative localization of parathyroid lesions in patients with hyperparathyroidism. Twenty-eight patients (19 men, 9 women; mean age, 56 years) with clinical and laboratory evidence of hyperparathyroidism underwent preoperative color Doppler ultrasonography and ultrasound-guided FNAC prior to surgery. On ultrasonography, the parathyroid lesions were anechoic or hypoechoic, located behind or at the margin of the thyroid gland, and mimicked blood vessels in some cases. On color Doppler ultrasound, parathyroid lesions showed little or no vascularity. They were easily differentiated from blood vessels, thus improving the safety of ultrasound-guided FNAC. Thirty-four (76%) of 45 surgically confirmed parathyroid lesions were detected with ultrasonography in 21 (75%) of the patients. There was no significant difference in the detection rates of lesions in the right upper, right lower, left upper, and left lower parathyroid glands. Eight (29%) patients had coexisting thyroid lesions. FNAC of the ultrasound-detected abnormalities provided preoperative confirmation that they were parathyroid lesions. In conclusion, our findings show that color Doppler ultrasonogrphy in combination with ultrasound-guided FNAC is useful for preoperative localization of parathyroid lesions.

Biopsy, Needle↗

PubMed1999

De novo RET proto-oncogene mutation in a patient with multiple endocrine neoplasia type 2B.

We report a case of multiple endocrine neoplasia type 2B (MEN 2B) with de novo RET proto-oncogene mutation. The patient, a 23-year-old Taiwanese woman, was admitted for treatment of recurrent medullary thyroid cancer (MTC) 7 years after a total thyroidectomy. Mucosal neuromas and marfanoid appearance were also noted. Because MEN 2B was suspected, the patient and her family members underwent genetic analysis. A heterozygous germline mutation at codon 918 (ATG-->ACG) of the proto-oncogene RET was detected in the patient. This mutation was considered de novo, as it was not detected in either of her parents or her siblings. The patient underwent surgery for removal of the recurrent tumor. Although no pheochromocytoma was noted, regular follow-up is necessary because of persistent hypercalcitoninemia.

Adult↗

PubMed1999

High-risk human papillomavirus deoxyribonucleic acid as an adjunct marker in cervical cytology.

BACKGROUND: This study was designed to determine whether screening for high-risk human papillomaviruses testing could improve the detection of cervical dysplasia and cancer in assistance with conventional Papanicoloau (Pap) smears. METHODS: The study was based on 114 patients with abnormal Pap smears referred for colposcopy from Feb. 1997 to Dec. 1997. The presence of high-risk human papillomavirus (HPV) DNA was determined with the Hybrid Capture method (including HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68). Cytologic examination by Papanicolaou smear was based on the Bethesda system and cervical biopsy was done via colposcopy. RESULTS: Cytologic examination demonstrated high-grade squamous intraepithelial lesions (HSIL) in 24 patients with HPV positive (75%), low-grade squamous intraepithelial lesions (LSIL) in 38 with 61% HPV positive, and atypical squamous cells of undetermined significance (ASCUS) in 52 with 37% HPV positive. Among patients with a cytologic diagnosis of borderline abnormalities (ASCUS or LSIL), those with who were HPV positive were significantly more likely to have cervical dysplasia (both p < 0.05). The sensitivity of combined HPV assay and/or cytology for detection of noninvasive precursor (91%) was significantly greater than those of cytology (68%) or HPV assay (81%) alone. CONCLUSION: The addition of the hybrid capture high-risk HPV DNA assay to cytologic examination of cervical smears appears to increase the sensitivity of cervical screening. Our findings suggest that HPV DNA may be a useful adjunct marker for early detection of cervical dysplasia in women with minimally abnormal Pap smears (ASCUS/low-grade SIL).

Biomarkers↗

PubMed1998

Prognostic factors in surgically treated small cell cervical carcinoma followed by adjuvant chemotherapy.

BACKGROUND: Small cell carcinoma of the uterine cervix is an uncommon tumor associated with high mortality even among patients with early stage disease. The role of adjuvant chemotherapy after surgery has been suggested by regimens used for small cell lung carcinoma. During the years 1980-1997, 19 cases in which various adjuvant chemotherapies were given after hysterectomy were reported in the literature published in English. METHODS: Adjuvant chemotherapy was administered consecutively to 23 patients with Stage Ib-II small cell cervical carcinoma who had been primarily treated with radical hysterectomy and had adequate bone marrow, renal, and hepatic functions. A combination of vincristine, doxorubicin, and cyclophosphamide alternating with cisplatin and etoposide (VAC/PE) was administered to 14 patients during the years 1988-1996 according to a prospective study protocol. A combination of cisplatin, vinblastine, and bleomycin (PVB) was administered to 8 patients, and another regimen was administered to 1 patient during the years 1984-1988. Prognostic factors were evaluated by analyzing both the data on these 23 patients and the pooled data on the cases retrieved from the literature and our own files. RESULTS: Ten of the 14 patients who received VAC/PE had no evidence of disease during a median follow-up of 41 months, whereas 3 of the 9 who received PVB or another regimen survived. Of the 10 patients who died of their disease, all died of distant metastasis within 10 months after recurrence. Meta-analysis of the pooled data showed that 68% of patients who received regimens containing VAC or PE survived, whereas 33% of patients who received regimens not containing VAC/PE survived (P = 0.0078, log rank test). Seventy percent of patients with no lymph node metastasis at hysterectomy and 35% with lymph node metastasis survived (P = 0.05). All patients who died of disease had extrapelvic metastasis. CONCLUSIONS: Chemotherapies containing VAC or PE are favorable regimens for patients with early stage small cell cervical carcinoma after radical hysterectomy.

Adult↗

PubMed1998

The prognostic significance of pre- and posttreatment SCC levels in patients with squamous cell carcinoma of the cervix treated by radiotherapy.

PURPOSE: To investigate the prognostic significance of the pre- and posttreatment serum squamous cell carcinoma antigen (SCC) levels in patients with Stage I-IVA squamous cell carcinoma of the cervix primarily treated by radiotherapy. MATERIALS AND METHODS: 401 patients with squamous cell carcinoma of cervix primarily treated with radiotherapy (RT) were included in this study. All had preRT, and 249 patients had postRT serum SCC values. The association of pretreatment SCC level with the clinical parameters, including stage, hemoglobin (Hb) level, age, cell differentiation, and lymph node status, was assessed by univariate and multivariate analysis. The prognostic significance of pretreatment SCC level and these clinical parameters were evaluated. The impact of postRT residual induration and SCC levels on survival was analyzed. RESULTS: 1. PreRT SCC level strongly correlated with stage. After controlling for stage, only SCC levels higher than 10 ng/ml were associated with enlarged lymph nodes shown in CT scan. No association of preRT SCC level with other clinical parameters was found. 2. SCC level higher than 10 ng/ml, but not between 2-10 ng/ml, had significant impact on survival in a multivariate analysis. Stage, Hb levels (<10 g/dl) and positive lymph node shown by CT scan were also independent prognostic factors for survival. No significant difference in failure pattern in terms of local and/or distant sites was found in patients with different SCC levels. 3. Patients with residual induration and/or persistently elevated SCC level at 2-3 months after RT had a significantly higher incidence of treatment failure. Persistently elevated SCC level is a stronger predictor for treatment failure than residual induration by pelvic examination, and is associated with a higher incidence of distant metastasis. One third of patients with initial SCC level higher than 10 ng/ml had persistently elevated SCC. CONCLUSION: Pretreatment SCC levels higher than 10 ng/ml are an independent predictor for poor prognosis in patients included in this study, and can be used as one of the prognostic factors for selection of patients for intensive treatment. Persistently elevated SCC levels after RT is a strong predictor for treatment failure. A combination of clinical pelvic examination and SCC levels provides useful information for the need of further work-up and management.

Adult↗

PubMed1998

Solvent kinetic isotope effects of human placental alkaline phosphatase in reverse micelles.

Human placental alkaline phosphatase was embedded in a reverse micellar system prepared by dissolving the surfactant sodium bis(2-ethylhexyl) sulphosuccinate (Aerosol-OT) in 2,2, 4-trimethylpentane. This microemulsion system provides a convenient instrumental tool to study the possible kinetic properties of the membranous enzyme in an immobilized form. The pL (pH/p2H) dependence of hydrolysis of 4-nitrophenyl phosphate has been examined over a pL range of 8.5-12.5 in both aqueous and reverse micellar systems. Profiles of log V versus pL were Ha-bell shaped in the acidic region but reached a plateau in the basic region in which two pKa values of 9.01-9.71 and 9.86-10.48, respectively, were observed in reverse micelles. However, only one pKa value of 9.78-10.27 in aqueous solution was detected. Profiles of log V/K versus pL were bell-shaped in the acidic region. However, they were wave-shaped in the basic region in which a residue of pKa 9.10-9.44 in aqueous solution and 8.07-8.78 in reverse micelles must be dehydronated for the reaction to reach an optimum. The V/K value shifted to a lower value upon dehydronation of a pKa value of 9.80-10.62 in aqueous solution and 11.23-12.17 in reverse micelles. Solvent kinetic isotope effects were measured at three pL values. At pL 9.5, the observed isotope effect was a product of equilibrium isotope effect and a kinetic isotope effect; at pL 10.4, the log V/K value was identical in water and deuterium. The deuterium kinetic isotope effect on V/K was 1.14 in an aqueous solution and 1.16 in reverse micelles. At pL 11.0 at which the log V values reached a plateau in either solvent system, the deuterium kinetic isotope effect on V was 2.08 in an aqueous solution and 0.62 in reverse micelles. Results from a proton inventory experiment suggested that a hydron transfer step is involved in the transition state of the catalytic reaction. The isotopic fractionation factor (pi) for deuterium for the transition state (piT) increased when the pH of the solution was raised. At pL 11.0, the piT was 1.07 in reverse micelles, which corresponds to the inverse-isotope effect of the reaction in this solvent system. Normal viscosity effects on kcat and kcat/Km were observed in aqueous solution, corresponding to a diffusional controlled physical step as the rate-limiting step. We propose that the rate-limiting step of the hydrolytic reaction changes from phosphate releasing in aqueous solution to a covalent phosphorylation or dephosphorylation step in reverse micelles.

Alkaline Phosphatase↗

PubMed1998

Differential properties of D4/LyGDI versus RhoGDI: phosphorylation and rho GTPase selectivity.

RhoA/B/C and CDC42/Rac, which form two subgroups of the rho guanosine triphosphatase (GTPase) family, regulate various aspects of actin cytoskeleton organisation. In cytosol, guanosine diphosphate (GDP) dissociation inhibitor (GDI) interacts with and maintains rho GTPases in their inactive GDP-bound form. RhoGDI is a ubiquitously expressed GDI, whereas D4/LyGDI is hematopoietic cell-specific and 10-fold less potent than RhoGDI in binding to and regulating rho GTPases. We have combined microanalytical liquid chromatography with the use of specific antibodies in order to separate D4/LyGDI and RhoDGI-complexes from the cytosol of U937 cells and to demonstrate that the two GDIs associate with different rho protein partners. RhoGDI can form a complex with CDC42Hs, RhoA, Rac1 and Rac2, while none of these GTPases was found to interact with D4/LyGDI. In addition, we found that stimulation of U937 cells with phorbol ester leads to phosphorylation of D4/LyGDI. Our results suggest that LyGDI forms complexes with specific rho GTPases expressed in hematopoietic cells where it may regulate specific pathways.

Amino Acid Sequence↗

PubMed1998

Isolation and characterization of a novel 98-kd Dermatophagoides farinae mite allergen.

BACKGROUND: Exposure to allergens from house dust mites is a significant cause of immediate hypersensitivity. Thus far, the active mite allergens defined are low molecular weight (MW) proteins or glycoproteins. However, other important mite allergens remain to be investigated. In this study a high MW mite antigen with a high IgE-binding activity was characterized. METHODS: An anti-Dermatophagoides farinae (Df) monoclonal antibody, mAb642, which recognized a 98-kd allergenic mite protein, was used for affinity chromatography. The purified Df642 was characterized biochemically and immunologically. RESULTS: Competitive ELISA demonstrated that mAb642 was inhibited by the interaction between serum IgE from allergic patients and Df642 antigen in a dose-dependent fashion. The IgE reactivity to both 98-kd and 92-kd components was removed or diminished by preincubation of asthmatic sera with Df642-coated CNBr-activated cellulose-4B gel. Two-dimensional immunoblot analysis revealed that there are at least 4 isoforms of Df642 that represent a minor component in the crude mite extract. The allergenicity of Df642 was assayed by IgE immunoassay with a large panel of 67 sera from asthmatic patients with positive skin reactions, and Df 642 showed positive IgE reactivity with more than 80% of the sera tested. Thus it should be classified as an important allergen. In addition, amino acid sequence analysis revealed that Df642 shares more than 50% homology with paramyosin from invertebrates. CONCLUSION: We have identified and characterized a 98-kd house dust mite allergen that showed greater than 80% IgE reactivity with sera from patients allergic to mites. This is the first high MW allergen characterized to date, and it shares high sequence homology with paramyosins in invertebrates.

Adolescent↗

PubMed1998

Direct antimicrobial susceptibility testing of gram-negative bacilli in blood cultures by an electrochemical method.

Nonfastidious aerobic gram-negative bacilli (GNB) are commonly isolated from blood cultures. The feasibility of using an electrochemical method for direct antimicrobial susceptibility testing of GNB in positive blood cultures was evaluated. An aliquot (10 microliter) of 1:10-diluted positive blood cultures containing GNB was inoculated into the Bactometer module well (bioMérieux Vitek, Hazelwood, Mo.) containing 1 ml of Mueller-Hinton broth supplemented with an antibiotic. Susceptibility tests were performed in a breakpoint broth dilution format, with the results being categorized as resistant, intermediate, or susceptible. Seven antibiotics (ampicillin, cephalothin, gentamicin, amikacin, cefamandole, cefotaxime, and ciprofloxacin) were used in this study, with each agent being tested at the two interpretive breakpoint concentrations. The inoculated modules were incubated at 35 degreesC, and the change in impedance in each well was continuously monitored for 24 h by the Bactometer. The MICs of the seven antibiotics for each blood isolate were also determined by the standardized broth microdilution method. Of 146 positive blood cultures (1,022 microorganism-antibiotic combinations) containing GNB tested by the direct method, the rates of very major, major, and minor errors were 0, 1.1, and 2.5%, respectively. The impedance method was simple; no centrifugation, preincubation, or standardization of the inocula was required, and the susceptibility results were normally available within 3 to 6 h after inoculation. The rapid method may allow proper antimicrobial treatment almost 30 to 40 h before the results of the standard methods are available.

Amikacin↗