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C G J Sweep

Publications and source records attributed to C G J Sweep.

At least 19 recordsLinked to original sources
PubMed2004

Hexosamines are unlikely to function as a nutrient-sensor in 3T3-L1 adipocytes: a comparison of UDP-hexosamine levels after increased glucose flux and glucosamine treatment.

Whether the hexosamine biosynthesis pathway acts as a nutrient-sensing pathway is still unclear. Glucose is directed into this pathway by GFAT. Because the activity of GFAT is tightly regulated, we examined whether UDP-hexosamine levels can increase significantly and dose-dependently in response to elevated glucose concentrations. In glucosamine-treated 3T3-L1 adipocytes, inhibition of insulin-stimulated glucose uptake was highly correlated with UDP-hexosamine levels (r = -0.992; p < 0.0001 for UDP-GlcNAc and r = -0.996; p < 0.0001 for UDP-GalNAc). Incubation of 3T3-L1 adipocytes with 0.1 microM insulin for 24 h in medium containing 1 and 5 mM glucose increased the rate of glucose uptake by 365% and 175% compared to untreated cells, respectively. This increase was not observed when the cells were incubated for 24 h with insulin in medium containing 10 or 25 mM glucose. However, treatment of cells with insulin and 1, 5, 10, or 25 mM glucose resulted in similar increases in levels of UDP-GlcNAc and UDP-GalNAc that always amounted to approx 30-40% above baseline values. This led us to conclude that despite exposure of adipocytes to conditions of extreme and prolonged glucose disposal, the increases in cellular UDP-hexosamines were minimal and not dependent on the extracellular glucose concentration. Taken together, our results are in line with the hypothesis that in glucosamine-treated adipocytes UDP-hexosamines influence insulin-stimulated glucose uptake. However, our observations in glucose-treated adipocytes argue against the possibility that UDP-hexosamines function as a nutrient-sensor, and question the role of the hexosamine biosynthesis pathway in the pathogenesis of insulin resistance.

3T3-L1 Cells↗
PubMed2003

Vascular endothelial growth factor is associated with the efficacy of endocrine therapy in patients with advanced breast carcinoma.

BACKGROUND: Vascular endothelial growth factor (VEGF) is a mediator of angiogenesis and is associated with a poor prognosis in patients with primary breast carcinoma. In the current study, the authors investigated whether there was an association between VEGF levels in tumor tissues and response rates to first-line, systemic therapy in patients with advanced breast carcinoma. METHODS: In 172 tumors from patients with primary breast carcinoma who developed distant metastases during follow-up, cytosolic levels of VEGF were measured using a quantitative enzyme-linked immunosorbent assay. Patients received either endocrine therapy (n = 96) or chemotherapy (n = 76) as first-line treatment after they were diagnosed with advanced disease. RESULTS: In univariate logistic regression analysis for response to endocrine therapy in 96 patients, an increasing level of VEGF, as a log-transformed, continuous variable, was correlated with a poor rate of response (P = 0.043). In multivariate analysis, a significantly lower rate of response to first-line endocrine therapy was found for patients who had high VEGF levels compared with patients who had low VEGF levels (P = 0.025). Similar results were found for the subgroup of 82 patients who received tamoxifen (P = 0.011). An association of VEGF with response to first-line endocrine therapy was found in addition to a predictive impact for estrogen receptor/progesterone receptor status (P = 0.027). VEGF levels did not predict the rate of response to first-line chemotherapy. CONCLUSIONS: The results demonstrated that the level of VEGF affects response to endocrine therapy independent of steroid hormone receptor status and may help to refine further the indication for this treatment in individual patients. Further studies are warranted to explain this underlying resistance to endocrine therapy.

Adult↗
PubMed2003

Cyclin-E is a strong predictor of endocrine therapy failure in human breast cancer.

Recently, cyclin-E was reported to be the most prominent prognostic factor for breast cancer outcome described so far, even surpassing axillary nodal involvement. Earlier studies on the prognostic value of cyclin-E in breast cancer, however, yielded heterogeneous results. Therefore, we set out to confirm and extend these results by quantitative Taqman RT-PCR of cyclin-E levels in 277 resectable breast cancers. Cyclin-E levels were not associated with relapse-free survival (RFS) or overall survival (OS) in the total cohort of patients, or in the subset of patients without involved lymph nodes that were not treated with adjuvant systemic therapy. Besides several classical clinicopathological factors, the interaction between cyclin-E and adjuvant endocrine therapy (P=0.01, HR=3.04, 95% CI: 1.30-7.09) was found to contribute significantly in multivariate analyses. Cyclin-E levels were associated with poor RFS specifically in patients treated with adjuvant endocrine therapy (n=108, P=0.001, HR=4.01, 95% CI: 1.76-9.12), independent of estrogen receptor status. In conclusion, cyclin-E is not a pure prognostic factor in breast cancer, but rather a predictor of failure of endocrine therapy. Differences in literature on the presumed prognostic value of cyclin-E may be due to differences in treatment. Assessment of cyclin-E levels can aid in improving adjuvant treatment selection.

Adult↗
PubMed2003

Carbonic anhydrase-9 expression levels and prognosis in human breast cancer: association with treatment outcome.

Here, we set out to assess CA9 expression levels by real-time quantitative RT-PCR in breast cancer tissue samples obtained from 253 patients, and correlated those with relapse-free (RFS) survival. The median follow-up time was 75 months (range 2-168 months). CA9 expression was mainly found in high-grade, steroid receptor negative cancer tissues. CA9 levels were not significantly associated with RFS (P=0.926, hazard ratio (HR)=0.99, 95% CI=0.80-1.22) in the total cohort of 253 patients. In multivariate analysis with other clinicopathological factors, CA9 (P=0.018, HR=0.77, 95% CI=0.62-0.96), the interaction of adjuvant chemotherapy with CA9 (P=0.009, HR=1.31, 95% CI=1.07-1.61) and the interaction of adjuvant endocrine therapy with CA9 (P<0.001, HR=1.41, 95% CI=1.20-1.66) all contributed significantly to the final model. These results indicate that patients with low CA9 levels benefit more from adjuvant treatment than do patients with high levels. Thus, the determination of CA9 levels could aid in the selection of patients who will not benefit from adjuvant therapy, and whose prognosis will more likely improve with other treatment modalities.

Antigens, Neoplasm↗
PubMed2003

Matrix metalloproteinase inhibitor reversion-inducing cysteine-rich protein with Kazal motifs: a prognostic marker for good clinical outcome in human breast carcinoma.

BACKGROUND: The recently described reversion-inducing cysteine-rich protein with Kazal motifs (RECK) inhibits membrane Type 1 matrix metalloproteinase (MMP-14), MMP-2, and MMP-9 secretion and enzymatic activity. Its expression is essential for normal vasculogenesis. Down-regulation of RECK has been implicated in tumor angiogenesis and progression. METHODS: The authors assessed the prognostic value of RECK expression in tumor tissue specimens from 278 breast carcinoma patients with a median follow-up time of 75 months (range, 2-169 months). RECK mRNA levels were measured by real-time quantitative reverse transcriptase-polymerase chain reaction. RESULTS: Expression levels of RECK were lower in tumor tissue specimens than in adjacent normal breast tissue specimens from 10 patients (P = 0.028). No relevant associations of RECK with established clinicopathologic factors or treatment regimens were found. RECK expression predicted a longer recurrence-free survival time (RFS; P = 0.037) at the optimal cutoff value (hazard ratio, 0.66; 95% confidence interval, 0.44-0.98). The 100 patients whose tumors exhibited low levels of RECK had a mean RFS time of 80.4 months and a 61.8% 5-year RFS rate, whereas the 178 patients with tumors with high RECK expression had a mean RFS time of 91.2 months and a 73.0% 5-year RFS rate. Multivariate Cox regression analysis showed that RECK expression maintained a significant independent prognostic value for RFS time (P = 0.047). CONCLUSIONS: These results are in agreement with the notion of RECK being an important tumor-suppressor gene. Therefore, the possibility of applying RECK, a pharmaceutical mimetic, or drugs activating endogenous RECK expression, as possible therapeutic or preventive agents for breast carcinoma should be explored.

Biomarkers, Tumor↗
PubMed2003

Inhibition of protein kinase CbetaII increases glucose uptake in 3T3-L1 adipocytes through elevated expression of glucose transporter 1 at the plasma membrane.

The mechanism via which diacylglycerol-sensitive protein kinase Cs (PKCs) stimulate glucose transport in insulin-sensitive tissues is poorly defined. Phorbol esters, such as phorbol-12-myristate-13-acetate (PMA), are potent activators of conventional and novel PKCs. Addition of PMA increases the rate of glucose uptake in many different cell systems. We attempted to investigate the mechanism via which PMA stimulates glucose transport in 3T3-L1 adipocytes in more detail. We observed a good correlation between the rate of disappearance of PKCbetaII during prolonged PMA treatment and the increase in glucose uptake. Moreover, inhibition of PKCbetaII with a specific myristoylated PKCbetaC2-4 peptide inhibitor significantly increased the rate of glucose transport. Western blot analysis demonstrated that both PMA treatment and incubation with the myristoylated PKCbetaC2-4 pseudosubstrate resulted in more glucose transporter (GLUT)-1 but not GLUT-4 at the plasma membrane. To our knowledge, we are the first to demonstrate that inactivation of PKC, most likely PKCbetaII, elevates glucose uptake in 3T3-L1 adipocytes. The observation that PKCbetaII influences the rate of glucose uptake through manipulation of GLUT-1 expression levels at the plasma membrane might reveal a yet unidentified regulatory mechanism involved in glucose homeostasis.

3T3-L1 Cells↗
PubMed2003

Phlorizin treatment prevents the decrease in plasma insulin levels but not the progressive histopathological changes in the pancreatic islets during aging of Zucker diabetic fatty rats.

A hallmark of Type 2 diabetes mellitus (T2DM) is chronic hyperglycemia, which is thought to play a role in pancreatic beta-cell failure. Here we investigated whether treatment of Zucker diabetic fatty (ZDF) rats, an animal model for T2DM, with the renal glucose transport inhibitor phlorizin could prevent alterations in the pancreatic islets. ZDF rats were treated with phlorizin or vehicle for 13 weeks starting with 6-week-old rats and before the onset of hyperglycemia. During the treatment, blood glucose levels in sham-treated ZDF rats increased rapidly from 7.7 +/- 0.3 to 24.8 +/- 0.6 mmol/l, whereas those in phlorizin-treated ZDF rats increased only slightly, but significantly, from 7.0 +/- 0.2 to 8.9 +/- 0.6 mmol/l. Phlorizin prevented the decrease in plasma insulin levels and caused a higher increase in body weight of the ZDF rats. Compared to 6-week-old untreated ZDF rats, in 19-week-old sham- and phlorizin-treated ZDF rats similar changes were found in islet architecture (more irregular boundaries and a disrupted mantle of peripheral islet cells) and in the mitochondria at the ultrastructural level (swelling of the matrix and disruption of the cristae). Using reverse transcriptase-polymerase chain reaction, no differences in mRNA expression levels were found for insulin, islet amyloid polypeptide (IAPP), and the prohormone convertase (PC) 1 and PC2 between 6-week-old untreated ZDF rats and 19-week-old sham- and phlorizin-treated ZDF rats. However, immunohistochemistry revealed similar decreases in insulin and IAPP protein expression in 19-week-old sham- and phlorizin-treated ZDF rats compared to those in 6-week-old untreated ZDF rats. These observations indicate that during aging of ZDF rats phlorizin treatment does not prevent the decreases in insulin and IAPP protein expression and the progressive histopathological changes in the pancreatic islets. Therefore, it is highly unlikely that these changes are caused by chronic hyperglycemia.

Aging↗
PubMed2003

Monitoring of menstrual cycles, ovulation, and adrenal suppression by saliva sampling in female patients with 21-hydroxylase deficiency.

OBJECTIVE: To investigate the correlation between menstrual cycles, ovulation, and adrenal suppression in congenital adrenal hyperplasia. DESIGN: Prospective observational study. SETTING: An academic outpatient clinic. PATIENT(S): Five females with salt-wasting 21-hydroxylase deficiency, aged 15.5 to 22.9 years; one had amenorrhea, one had irregular bleeding, and three had regular bleeding. INTERVENTION(S): Daily morning saliva sampling for 40 to 280 days. MAIN OUTCOME MEASURE(S): Salivary levels of progesterone (P), 17-hydroxyprogesterone (17-OHP), and androstenedione. RESULT(S): In the amenorrheic patient, the elevated P and 17-OHP levels decreased when the glucocorticoid dose was increased, and subsequently menarche occurred. The androstenedione levels were normal. The correlations between P and 17-OHP levels before and after menarche suggest that adrenal progesterone had prevented menarche. The patient with irregular bleeding showed slightly elevated androstenedione levels and increased levels of 17-OHP and P in an irregular pattern, without correlation in time with vaginal bleeding. Three patients with regular cycles showed a biphasic pattern of P levels, indicating ovulation. CONCLUSION(S): These longitudinal data support the hypothesis that menstrual cycling in females with 21-hydroxylase deficiency can be prevented or disturbed by elevated progesterone levels of adrenal origin, in the absence of androgen excess. Increasing glucocorticoid dose could suppress adrenal progesterone production, resulting in menarche.

17-alpha-Hydroxyprogesterone↗
PubMed2003

The prognostic value of the mitotic activity index in patients with primary breast cancer who were not treated with adjuvant systemic therapy.

BACKGROUND: At the St Gallen meeting of 2001 it was agreed to select high-risk patients for adjuvant systemic therapy by lymph node status, tumor size, age, hormone receptor status, and histological grade. In The Netherlands it was chosen to use either the histological grade or the mitotic activity index (MAI). The aim of this study was to retrospectively evaluate the independent prognostic value of the MAI in primary breast cancer patients, who were not treated with adjuvant systemic therapy, on relapse-free survival (RFS) and overall survival (OS). PATIENTS AND METHODS: The data of 137 systemically untreated patients with primary breast cancer diagnosed between 1992 and 1996, of whom MAI was assessed, were retrospectively collected. The MAI was correlated to classical prognostic factors and we determined the prognostic value of the MAI, the histological grade and other prognostic factors. RESULTS: The median observation time was 4.2 years. The MAI showed a positive correlation to lymph node status (P < 0.001) and a negative correlation to age (P = 0.005), menopausal status (P < 0.001) and the ER and PgR status (r(s) = -0.390 [ER], r(s) = -0.440 [PgR], both P < 0.001). A high MAI (> or = 15) predicted a reduced RFS and OS in the Kaplan-Meier analysis (P = 0.0070 and P = 0.0017, respectively). Also in the multivariate analysis, the MAI showed to be an independent predictor of poor RFS (P = 0.035), in addition to lymph node status. However, the MAI did not predict for OS, in contrast to tumor size and lymph node status. CONCLUSION: The present study confirms that the MAI is an independent prognostic factor for RFS, but not for OS and may be useful for daily clinical practice.

Adult↗
PubMed2003

E1AF expression levels are not associated with prognosis in human breast cancer.

E1AF is a transcription factor involved in regulation of several metastasis-associated genes, and is associated with overexpression of HER2/neu. We were unable to find a clear prognostic value of E1AF expression in human breast cancer. Furthermore, no association of E1AF levels with HER2/neu mRNA levels, hormone receptor status, histological grade, tumor size, or lymph node involvement was found.

Adenovirus E1A Proteins↗
PubMed2003

Elements regulating angiogenesis and correlative microvessel density in benign hyperplastic and malignant prostate tissue.

PURPOSE: To quantify the ex vivo production of proangiogenic proteins (vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (tPA)) and angiogenesis inhibitors (plasminogen activator inhibitor type-1 (PAI-1) and angiostatin) from epithelial and stromal components of primary prostate cancer (CaP) and benign prostatic hyperplasia (BPH) cultures. To perform microvessel density (MVD) counts on sections of BPH and CaP from the same prostatectomy specimens. SCOPE: Angiogenic cytokine expression was measured by immunoassays and in vitro angiostatin generating capacities assessed using immunoblotting. CaP and BPH tissue was immunostained using factor VIII antibody to determine MVD. CONCLUSIONS: Elements regulating angiogenesis are present in both primary cultures of CaP and BPH, suggesting that angiogenic ability is well established in the absence of carcinoma.

Angiogenic Proteins↗
PubMed2003

Antecedent adrenaline attenuates the responsiveness to but not the release of counterregulatory hormones during subsequent hypoglycemia.

Hypoglycemia unawareness is thought to be the consequence of recurrent hypoglycemia, yet the underlying mechanism is still incompletely understood. The aim of the present study was to determine the role of antecedent elevated adrenaline in the pathogenesis of hypoglycemia unawareness. Sixteen healthy volunteers (eight of either sex) participated in two experiments, performed in random order and at least 3 wk apart. During the morning, three consecutive doses of 0.04, 0.06, and 0.08 microg.kg(-1).min(-1) of adrenaline or matching placebo (normal saline) were infused for the total duration of 1 h. Three hours later, a hyperinsulinemic (360 pmol.m(-2).min(-1)) two-step hypoglycemic (5.0-3.5-2.5 mmol.liter(-1)) clamp study was performed. During hypoglycemia, hypoglycemic symptoms, counterregulatory hormones, cardiovascular responses, and cognitive function were monitored. Hypoglycemia induced similar responses of autonomic and neuroglycopenic symptoms, counterregulatory hormones, and lengthening in reaction time on the choice reaction time task, irrespective of antecedent infusions. However, prior adrenaline was associated with higher exogenous glucose requirements at hypoglycemic nadir (10.1 +/- 1.3 vs. 7.3 +/- 1.3 micromol.kg(-1).min(-1), P = 0.017), an attenuated hypoglycemia-induced fall in blood pressure (mean arterial pressure, -13 +/- 2 vs. -8 +/- 2 mm Hg, P = 0.006), and preserved cognitive function as assessed by the symbol digit test during hypoglycemia, when compared with prior placebo. We conclude that elevated adrenaline attenuates the responsiveness to, but not the release of counterregulatory hormones during subsequent hypoglycemia. As such, adrenaline's role in the development of hypoglycemia unawareness is limited.

Adrenergic Agonists↗
PubMed2003

An improved procedure for testing for assay linearity.

BACKGROUND: Statistical testing of assay linearity using replicate measurements made on binary mixtures of samples provides no information about the significance of any detected deviations from linearity, which may often be desirable. METHOD: Performance of additional statistical analysis of the assay data. RESULT: Objective measures for non-linearity and the minimum detectable deviation from linearity of the assay are obtained. CONCLUSION: A few additional calculations from the available data make it possible to assess whether or not an assay method needs improvement to achieve adequate performance within its intended application.

Biochemistry↗
PubMed2003

Quantitative detection of peripheral thyroglobulin mRNA has limited clinical value in the follow-up of thyroid cancer patients.

BACKGROUND: As recurrences after treatment for differentiated thyroid cancer can occur many years after thyroidectomy, periodic monitoring of serum thyroglobulin (Tg) levels is performed in these patients. However, autoantibodies that can interfere with Tg immunoassays occur in the blood of approximately 25% of these patients. Several earlier reports suggest that measuring Tg mRNA by reverse-transcriptase polymerase chain reaction (RT-PCR) could be of value, especially in patients with Tg autoantibodies. METHODS: Using an earlier described, real-time quantitative Taqman RT-PCR assay, Tg mRNA concentrations were assessed in peripheral blood taken from 58 patients treated for thyroid cancer and from two healthy controls. RESULTS: In all tested samples Tg mRNA could be found. No correlation between serum Tg protein and Tg mRNA could be found. Tg mRNA concentrations did not differ between serum Tg-negative and Tg-positive patients. No differences in the number of patients with high or low Tg/beta-actin ratios were found between the groups of patients without, (131)I uptake on whole-body scan, or patients with thyroid bed uptake, uptake elsewhere in the neck, or distant metastases with or without regional uptake (P = 0.871). CONCLUSIONS: We were not able to confirm earlier positive reports on the clinical value of Tg mRNA measurement for the monitoring of patients treated for thyroid cancer.

Adult↗
PubMed2002

Expression of the transcription factor Ets-1 is an independent prognostic marker for relapse-free survival in breast cancer.

The transcription factor Ets-1 regulates the expression of several angiogenic and extracellular matrix remodeling factors, and might be implicated in disease progression of breast cancer. In the present study, the prognostic value of Ets-1 expression was assessed by quantitative real-time fluorescence RT-PCR in 123 sporadic primary breast cancer samples of patients with a median follow-up time of 62 months. Ets-1 expression levels correlated significantly with VEGF and PAI-1 in the same tissue. In univariate (P=0.0011) and multivariate (P=0.005) analyses, Ets-1 expression showed significant prognostic value for relapse-free survival. Ets-1 is a strong, independent predictor of poor prognosis in breast cancer. This seems - at least in part - to be attributable to its role in transcriptional regulation of factors involved in angiogenesis (VEGF), and extracellular matrix remodeling (PAI-1).

Analysis of Variance↗
PubMed2002

An ELISA avoiding interference by heterophilic antibodies in the measurement of components of the plasminogen activation system in blood.

Endogenous heterophilic antibodies in blood are known to interfere with two-site enzyme-linked immunosorbent assays (ELISAs) evoking false positive signals. In the present study, we describe an assay for the assessment of components of the plasminogen activation system (uPA, tPA and PAI-1, and their complexes) in blood which is not susceptible to interference by heterophilic antibodies. In the ELISA format, two avian (duck, chicken) antibodies are employed in the pre-analyte and two mammalian (rabbit, goat) antibodies in the post-analyte stage. The assay is compared to our earlier reported ELISA for measuring uPA, tPA and PAI-1 components in tumor tissue extracts. Applying the so-called "nonsense formats", designed against non-existent components, to the NIBSC reference preparation of rheumatoid factor (RF), no response was found with the new assay, whereas a clear RF dose-dependent interfering signal was observed with the original assay designed for tumor tissue extracts. Analysis of tumor-tissue based international reference preparations (RBG EORTC 101094 and 040297), human anti-mouse antibodies (HAMA) containing sera, and sera from patients with rheumatoid arthritis (RA), also displayed no false positive signals. In conclusion, we have developed an ELISA that permits the determination of blood levels of components in the urokinase system, free from disturbance by endogenous heterophilic antibodies.

Animals↗
PubMed2002

The prognostic value of vascular endothelial growth factor in 574 node-negative breast cancer patients who did not receive adjuvant systemic therapy.

The growth and metastasising capacity of solid tumours are dependent on angiogenesis. Vascular endothelial growth factor is a mediator of angiogenesis. In this study we investigated whether vascular endothelial growth factor is associated with the natural course of the disease in primary invasive breast cancer. In 574 tumours of patients with node-negative invasive breast cancer the cytosolic levels of vascular endothelial growth factor were measured using a quantitative enzyme-linked immunosorbent assay. These patients did not receive adjuvant systemic therapy and were followed for a median follow-up time of 61 months (range 2-155 months) after the primary diagnosis. Correlations with well-known prognostic factors, and univariate and multivariate survival analyses were performed. Vascular endothelial growth factor level was positively associated with age and tumour size (P=0.042 and P=0.029, respectively). In addition, vascular endothelial growth factor level was inversely, but weakly correlated with progesterone receptor levels (PgR) (r(s)=-0.090, P=0.035). A high vascular endothelial growth factor level (equal or above the median level of 0.53 ng mg(-1) protein) predicted a reduced relapse-free survival and overall survival in the univariate survival rate analysis (for both P=0.005). In the multivariate analysis as well, vascular endothelial growth factor showed to be an independent predictor of poor relapse-free survival and overall survival (P=0.045 and P=0.029, respectively), in addition to age, tumour size and PgR. The results show that cytosolic levels of vascular endothelial growth factor in tumour tissue samples are independently indicative of prognosis for patients with node-negative breast cancer who were not treated with adjuvant systemic therapy. This implies that vascular endothelial growth factor is related with the natural course of breast cancer progression.

Adult↗