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Biomedical subjects

I van der Tweel

Publications and source records attributed to I van der Tweel.

At least 19 recordsLinked to original sources
PubMed2005

Clinical prospective study of biochemical markers and evoked potentials for identifying adverse neurological outcome after thoracic and thoracoabdominal aortic aneurysm surgery.

BACKGROUND: Neurological deficit after repair of a thoracic or thoracoabdominal aortic aneurysm (TAA/TAAA) remains a devastating complication. The aim of our study was to investigate the clinical value of biochemical markers [S-100B, neurone-specific enolase (NSE) and lactate dehydrogenase (LD)], evoked potentials and their combinations for identifying adverse neurological outcome after TAA/TAAA surgery. METHODS: From 69 patients, cerebrospinal fluid and blood samples for biochemical analysis were drawn after the induction of anaesthesia, during the cross-clamp period, 5 min, 2, 4, 6, 8, and 19 h, respectively, after reperfusion. In addition, continuous perioperative recording of motor-evoked potentials after transcranial electrical stimulation (tcMEP) and somatosensory-evoked potentials was carried out. Furthermore, neurological examinations were performed. RESULTS: In patients with a defined decrease in lower extremity tcMEP during the cross-clamp period, we found that combinations of the serum concentrations of S-100B and tcMEP ratios at 4, 6, and 8 h after reperfusion had a positive and negative predictive value of 100% in predicting adverse neurological outcome after TAA/TAAA surgery. Furthermore, combinations of the serum concentrations of S-100B and NSE or LD at 19 h after reperfusion had both a positive and negative predictive value of 100% in identifying patients with adverse outcome after TAA/TAAA repair. CONCLUSIONS: TcMEP monitoring during TAA/TAAA surgery seems to be an effective but not completely sufficient guide in our protective multi-modality strategy. Combinations of the serum concentrations of S-100B and tcMEP ratios during the early reperfusion period might be associated with adverse neurological complications. Furthermore, biochemical markers could detect central nervous system injury on the first postoperative day and may have prognostic value.

Adult↗
PubMed2004

Surgical treatment of traumatic fractures of the thoracic and lumbar spine: a systematic review of the literature on techniques, complications, and outcome.

STUDY DESIGN: A systematic review of the literature, pertaining surgical treatment of traumatic thoracic and lumbar spine fractures, was performed. OBJECTIVES: To provide information on surgical techniques for traumatic spine fracture management, their respective performance and complication rates, based on previously published information. SUMMARY OF BACKGROUND DATA: The treatment of traumatic fractures of the thoracic and lumbar spine remains controversial. There is insufficient evidence in the literature to choose between the various surgical options. In absence of conclusive studies, a systematic review can be an alternative to obtain more convincing information. METHODS: Full-text papers from 1970 until 2001 were included if strict inclusion criteria were met. Five surgical subgroups were recognized: posterior short-segment (PS), posterior long-segment (PL), reports on both posterior short- and long-segment (PSL), anterior (A), and anterior combined with posterior (AP) techniques. Clearly defined and generally accepted parameters were scored and subsequently analyzed. The preoperative injury severity of the surgical groups was compared. The neurologic, radiologic, and functional outcome and complications of all groups were assessed. RESULTS: A total of 132 papers, the majority being retrospective case-series, were included representing 5,748 patients. The preoperative injury severity revealed an inequality between the subgroups. Partial neurologic deficits had the potential to resolve irrespective of treatment choice. None of the five techniques used was able to maintain the corrected kyphosis angle. The functional outcome after surgery seems to be better than generally believed. Complications are relatively rare. CONCLUSIONS: In general, surgical treatment of traumatic spine fractures is safe and effective. Surgical techniques can only be compared using randomized controlled trials.

Adult↗
PubMed2004

Quality of life: patients and doctors don't always agree: a meta-analysis.

OBJECTIVE: In addition to traditional clinical markers, quality-of-life assessment can be helpful to estimate the well-being of patients. Discrepancies in perception of well-being between physicians and patients may interfere with the effectiveness of treatment. A systematic review and meta-analysis were performed to explore the (dis-)agreement in quality-of-life assessments between patients and physicians. STUDY DESIGN AND SETTING: Data on the proportion agreement of paired observations were collected from Medline, Embase, Psychlit, and Social Abstracts. RESULTS: Of the 1,316 articles found, six met the selection criteria, four studied the proportion agreement between children and physicians, and all six the proportion agreement between parents and physicians. None examined the magnitude of over- or underestimation by physicians. The agreement was lower in the more subjective domains (0.54-0.77) in comparison to the more objective domains (0.79-0.94). CONCLUSION: Quality-of-life assessment should be integrated in clinical practice. During long-term treatment the perception of the patients' well-being by physicians and patients themselves can easily diverge from each other, resulting in misunderstandings about the treatment and its usefulness in relation to perceived quality of life, and may even become the base for noncompliance.

Attitude of Health Personnel↗
PubMed2003

Acute toxicity of concurrent adjuvant radiotherapy and chemotherapy (CMF or AC) in breast cancer patients. a prospective, comparative, non-randomised study.

The concurrent administration of adjuvant chemotherapy and radiotherapy in breast cancer treatment might lead to an increased incidence of side-effects. In this prospective, non-randomised, comparative study, the acute toxicity of radiotherapy alone (RT) and radiotherapy concurrent with doxorubicin-cyclophosphamide (AC/RT) and radiotherapy concurrent with cyclophosphamide-methotrexate-5-fluorouracil (CMF/RT) was compared. We used the common toxicity criteria (CTC) to score the level of acute toxicity before, during and 6 months after the completion of the period of irradiation. The number of hospital admissions, as well as the compliance of chemotherapy, were noted. We observed that patients treated with AC/RT and CMF/RT had significant higher incidences of (high-grade) skin-toxicity, oesophagitis, dyspnoea, malaise, anorexia, nausea and hospital admission compared with those treated with RT only. The target-volume of radiotherapy was the main predictor of (high-grade) acute skin toxicity and oesophagitis. AC/RT was associated with significant more (high-grade) skin toxicity than CMF/RT. The dose of chemotherapy was reduced to less than 85% of the planned dose in 11% of patients, 17% of patients treated with concurrent chemotherapy and radiotherapy needed admission to hospital. From the results of our study, we conclude that the concurrent administration of adjuvant chemotherapy and radiotherapy leads to an unacceptably high level of acute toxicity.

Adult↗
PubMed2003

Eye shielding during total body irradiation for bone marrow transplantation in children transplanted for a hematological disorder: risks and benefits.

This is a retrospective analysis of 188 children who underwent total body irradiation (TBI) in one or two fractions before bone marrow transplantation (BMT) for a hematological disorder. While 139 children had eye shielding during TBI to decrease cataract formation, 49 did not. The blocks used for shielding caused cylindrical areas of decreased dose intensity in the brain. The aim of the study was to determine if there was an increased risk of relapse in the eyes or in the CNS after shielding of the eyes. The probability and severity of cataract formation with and without shielding were also evaluated. None of the 49 children without shielding had a relapse in their eyes or in the CNS after BMT. Of the children with shielding, none had a relapse in the eyes but two of the 139 (1.4%) had a CNS relapse. The incidence of cataracts without shielding was 90% (19 of 21 evaluable patients), while with shielding it was 31% (20 of 64). Severe cataracts were present in eight of 21 (38%) patients without and two of 64 (3%) patients with shielding. The probability of staying cataract free for at least five years was 0.77 with and 0.33 without shielding, at 8 years it was 0.53 and 0.24 respectively. The relative risk of developing a cataract without shielding vs shielding was three (95% CI=1.5; 5.9). It appears that the incidence of relapse in the eyes and CNS is not increased when the eyes are shielded during TBI. Shielding increased the latency time of cataract formation and decreased the severity of cataracts.

Adolescent↗
PubMed2002

[Sequential analysis in clinical and epidemiological research].

In clinical trials and epidemiological studies, interim analyses are usually performed for ethical or economical reasons, although efficiency aspects can also be a reason. The analysis is referred to as group-sequential analysis or continuous-sequential analysis, dependent on the number of interim analyses performed. Repeated testing of cumulative data requires an adjustment to the significance level or type I error alpha of a statistical test. On average a (group-)sequential analysis of a clinical or epidemiological study requires less patients than the analysis of a fixed-sample study.

Clinical Trials as Topic↗
PubMed2001

Proliferative capacity in head and neck cancer.

BACKGROUND: Shortening of overall treatment time (accelerated radiotherapy) appears to result in an increase of the efficacy of irradiation. In this study, we compared the proliferative capacity between tumors originating in different sites of the head and neck region. Tumors with a large proliferating capacity might, theoretically, benefit most from accelerated radiotherapy. MATERIAL AND METHODS: BrdUrd was administered intravenously in patients with head and neck carcinomas. Tumor samples were analyzed with flow cytometry. T and N stages were assessed in accordance with the TNM classification system (UICC 1987). RESULTS: No significant differences in proliferation parameters were observed with respect to site of origin of head and neck tumors. For T3/T4 tumors, DNA ploidy is an important tumor characteristic: G1- and S-phase fractions, labeling index, and tumor doubling time Tpot differences were statistically significant; the aneuploid tumors showed the largest proliferative potential. CONCLUSIONS: (1) In general, no significant differences in proliferation parameters were observed with respect to site of origin. (2) Aneuploid head and neck tumors have a higher proliferative capacity than diploid ones, they might benefit most from accelerated irradiation.

Antimetabolites, Antineoplastic↗
PubMed2001

Prophylactic cranial irradiation in limited disease small-cell lung cancer in complete remission: a retrospective analysis.

Recently a meta-analysis showed an improved survival probability of prophylactic cranial irradiation (PCI) in limited disease small-cell lung cancer (LD SCLC) in complete remission after chemotherapy. We evaluated treatment results of PCI+ and PCI- in these patients. Whether PCI (n = 65) or no PCI (n = 37) was administered did not depend either on patients or on tumour characteristics. After 2 years the incidence of brain metastases was 11% in PCI+ patients and 51% in PCI- patients. Both disease-free survival and overall survival were significantly longer after PCI. PCI reduces the incidence of brain metastases, prolongs brain metastases-free period, and overall survival in LD SCLC patients in complete remission after chemotherapy.

Brain Neoplasms↗
PubMed2000

Cataract-free interval and severity of cataract after total body irradiation and bone marrow transplantation: influence of treatment parameters.

PURPOSE: To determine prospectively the cataract-free interval (latency time) after total body irradiation (TBI) and bone marrow transplantation (BMT) and to assess accurately the final severity of the cataract. METHODS AND MATERIALS: Ninety-three of the patients who received TBI as a part of their conditioning regimen for BMT between 1982 and 1995 were followed with respect to cataract formation. Included were only patients who had a follow-up period of at least 23 months. TBI was applied in one fraction of 8 Gy or two fractions of 5 or 6 Gy. Cataract-free period was assessed and in 56 patients, who could be followed until stabilization of the cataract had occurred, final severity of the cataract was determined using a classification system. With respect to final severity, two groups were analyzed: subclinical low-grade cataract and high-grade cataract. Cataract-free period and final severity were determined with respect to type of transplantation, TBI dose, and posttransplant variables such as graft versus host disease (GVHD) and steroid treatment. RESULTS: Cataract incidence of the analyzed patients was 89%. Median time to develop a cataract was 58 months for autologous transplanted patients. For allogeneic transplanted patients treated or not treated with steroids, median times were 33 and 46 months, respectively. Final severity was not significantly different for autologous or allogeneic patients. In allogeneic patients, however, final severity was significantly different for patients who had or had not been treated with steroids for GVHD: 93% versus 35% high-grade cataract, respectively. Final severity was also different for patients receiving 1 x 8 or 2 x 5 Gy TBI, from patients receiving 2 x 6 Gy as conditioning therapy: 33% versus 79% high-grade cataract, respectively. The group of patients receiving 2 x 6 Gy comprised, however, more patients with steroid treatment for GVHD. So the high percentage of high-grade cataract in the 2 x 6 Gy group might also have been caused to a significant extent by steroid treatment. The percentage of patients with high-grade cataract was lower in allogeneic transplanted patients without steroid treatment for GVHD than in autologous transplanted patients: 35% versus 48%. An explanation for this could be pretransplant therapy containing high-dose steroids. CONCLUSIONS: After high-dose-rate TBI in one or two fractions, steroids for GVHD influence latency time of a cataract and are of great importance for the severity the cataract finally attains. Although a cataract will develop in all patients, a clinically important high-grade cataract is relatively infrequent in patients not treated with steroids. Pretransplant therapy might also influence final severity of cataract.

Adolescent↗
PubMed2000

Influence of p53 and bcl-2 on proliferative activity and treatment outcome in head and neck cancer patients.

Knowledge about the influence of biomarkers on cell proliferative activity might explain differences in radiosensitivity between head and neck tumors and might improve patient selection for the most optimal treatment strategy. p53 and bcl-2 protein expression were determined immunohistochemically in 56 head and neck cancer patients, treated by surgery only in five cases and by radiotherapy, with or without surgery, in 51 cases. Relationships with various cell proliferation markers, determined by flow-cytometry (G1-phase fraction, S-phase fraction, BrdUrd-labeling index, duration of S-phase and potential doubling time) were investigated. Associations between these cell proliferation parameters, on the one hand, and both p53 and bcl-2, on the other, were not found. Furthermore, p53 and bcl-2 expression were both not related to clinicopathological parameters (T- and N-stage, site, grade) and did not affect loco-regional recurrence-free survival and/or disease-free survival. We could not find a prognostic value for both p53 and bcl-2 protein expression to differentiate radiosensitive from radioresistant head and neck tumors.

Adult↗
PubMed2000

Rebreathing K(CO) and single breath K(CO) measured at the same mean alveolar volume reveal a physiological relationship between unequal diffusion and unequal ventilation in normal subjects.

BACKGROUND: The single breath (SB) method for determining the transfer factor for carbon monoxide is influenced by an unequal distribution of diffusion and ventilation. The rebreathing (RB) method is thought not to be influenced by these inequalities. Therefore, a comparison of the results of the two methods enables us to investigate unequal ventilation and diffusion. We have previously shown that even in normal subjects unequal ventilation influences the relation between the transfer factor as measured by the RB method and by the SB method. OBJECTIVES: To investigate to what extent unequal diffusion influences the relation between the RB and SB transfer factor in normal subjects. METHODS: Measurements were performed in 8 normal subjects. Differences in alveolar volume as measured by the RB and SB method were prevented from influencing the results by comparing the RB and SB transfer factor per liter of alveolar volume, i.e. the RB and SB Krogh factor, instead of the RB and SB transfer factor. The effect of the known dependence of the Krogh factor on inspired volume was prevented by measuring the SB Krogh factor at an inspired volume equal to the mean inspired volume of the RB measurement. This SB Krogh factor was compared with the RB Krogh factor calculated as the quotient of the RB transfer factor and the mean alveolar volume during the RB measurement. RESULTS: This RB Krogh factor was always larger than the corresponding SB Krogh factor. The difference was significant (p = 0.006). A high percentage (80%) of the variance in the quotient of the two Krogh factors, which can be considered as a parameter for unequal diffusion, was explained by the variance in the quotient of the mean RB volume and the corresponding SB volume. The latter quotient is a measure of unequal ventilation. CONCLUSIONS: The finding suggests a physiological relation between unequal diffusion and unequal ventilation. A plausible explanation was found in the decrease of the Krogh factor with an increasing ratio of inspired volume to residual volume for each part of the lung separately. The consequence is that in the absence of unequal ventilation the RB transfer factor is equal to the SB transfer factor measured at an inspired volume equal to the mean RB inspired volume.

Adult↗
PubMed1999

Prognostic relevance of MIB-1 immunoreactivity, S-phase fraction, 5-bromo-2'-deoxyuridine labeling indices, and mitotic figures in gliomas.

Prognostic relevance of cell proliferation markers was evaluated in 27 glioma patients. By 1) flow cytometry (FCM), i.e., S-phase fraction (SPF), and BrdUrd-labeling index (LIfcm); 2) immunohistochemistry (IHC), i.e., BrdUrd-labeling index (LIihc) and MIB-1 immunoreactivity (MIB-1 LIihc); and 3) histologic examination, i.e., the presence or absence of cells in mitoses, were assessed. A longer local progression free survival (LPFS) was significantly associated with low SPF, low LIfcm, and low MIB-1 LIihc. For LIihc, no significant association was found. LIfcm appeared to be a more promising prognosticator than MIB-1 LIihc. In comparison with this marker, the presence or absence of mitotic figures appeared to be an even stronger prognosticator. Prognostic significance of LIfcm appeared to be of importance in low-grade gliomas. The number of patients in our study is limited. Our findings were: 1) the presence or absence of cells in mitoses (M-phase activity) appeared to be of more prognostic significance than LIfcm (S-phase activity) and MIB-1 LIihc (non-G0-phase activity); 2) of the tested experimental cell proliferation markers, LIfcm appeared to be of more prognostic significance than MIB-1 LIihc, SPF, and LIihc; and 3) LIfcm is likely to be an important prognosticator in low-grade gliomas and is, therefore, not definitive and only of potential interest.

Adult↗
PubMed1999

No effect of long-term physical activity on the glycemic control in type 1 diabetes patients: a cross-sectional study.

BACKGROUND: The main purpose of the present study was to assess the relation between long-term physical activity and glycemic control in patients with type 1 diabetes mellitus. METHODS: Medical data and blood samples for the determination of glycosylated hemoglobin (glyHb) were collected in 221 consecutive type 1 diabetes patients between 18 and 45 years of age without late complications. A self-report questionnaire was used to determine the degree of physical activity. Correlation coefficients and analysis of variance were used for statistical analyses. RESULTS: No correlation was observed between the different levels of physical activity and glycemic control. Females showed a significantly higher total physical activity index than males (p = 0.004), mostly due to the leisure time activity index. More active patients used a lower amount of insulin (r = -0.20, p = 0.002) than less active patients. CONCLUSIONS: Glycemic control was not found to be associated with long-term physical activity in type 1 diabetes patients. Physical activity did not negatively affect long-term glycemic control.

Adolescent↗
PubMed1999

Regional heterogeneity and intra-observer variability of DNA-content and cell proliferation markers determined by flow cytometry in head and neck tumours.

We analyzed regional heterogeneity of DNA content and of proliferative capacity. DNA-diploid as well as DNA-non-diploid tumour cell populations both were found to be present in 13% of the cases. The average coefficient of variation (CV) of DI appeared to be 2%. The CV's of G1PF, LI, and SPF, were 4%, 20%, and 25%, respectively. The CV's of Ts and for Tpot appeared to be 17% and 30%, respectively. The ratio of the intratumoural variability to the intertumoural variability, was lowest for DI. Intraobserver variability was evaluated. The correlation coefficient (CC) for LI and DI was 0.99 and 0.98, respectively, and for relative movement (RM) was 0.71. We concluded that for DI of head and neck tumours both representativity and reproducibility were better when compared with those for SPF, LI, G1PF, Ts, and Tpot.

Aged↗
PubMed1998

Interrelationships of DNA-ploidy and cell proliferation markers with T-stage and N-stage in primary laryngeal tumors.

PURPOSE: The purpose of this study was to evaluate the interrelationships of DNA-ploidy and cell proliferation markers with T-stage and N-stage in primary laryngeal tumors. METHODS AND MATERIALS: DNA-index, S-phase fraction (SPF), 5-bromo-2'-deoxy-uridine (BrdUrd)-labeling index (LI), duration of S-phase (Ts), and potential doubling time (Tpot) were determined by flow cytometry. T-stage and N-stage were assessed in accordance with the TNM classification system (UICC 1987). RESULTS: T1-2-, when compared with T3-4-stage tumors, had significantly higher LI values (independent from N-stage) resulting in lower Tpot values. No such relationship was found with respect to N-stage. N1-3 tumors, as opposed to NO tumors, appeared to be characterized by a significantly shorter Ts (and, hence, a shorter Tpot). Ts values appeared to vary considerably (range 1.9-6.2 h). For DNA-aneuploidy, as opposed to DNA-diploidy, a significantly higher geometric mean LI was noted. Locally advanced (T3-4) tumors, when compared with T1-2 tumors, were characterized by a significantly higher percentage of DNA-aneuploidy. CONCLUSIONS: The reported lack of prognostic relevance of cell proliferation markers to predict radiation treatment efficacy may relate to a decreased proliferative capacity (LI, Tpot) in locally advanced (T3-4) tumors, as found in our series. In laryngeal tumors, the predictive value of cell proliferation markers (LI, Tpot) should, therefore, be evaluated after stratification for T-stage. The existence of higher LI values in DNA-aneuploidy tumors was confirmed in our series, stressing the need for distinction of DNA-diploid tumor cells from DNA-diploid normal cells. The prognostic potential of DNA-index was confirmed.

Cell Division↗
PubMed1998

Prognostic significance of cell proliferation markers and DNA-ploidy in head and neck tumors.

PURPOSE: The purpose of this study was to evaluate the prognostic significance of cell proliferation markers and DNA ploidy in patients with a squamous cell carcinoma of the head and neck region. METHODS AND MATERIALS: With flow cytometry, DNA index, G1PF-phase fraction (G1PF), S-phase fraction (SPF), 5-bromo-2'-deoxy-uridine (BrdUrd) labeling-index (LI), and potential doubling time (Tpot), were determined. T-stage and N-stage were assessed in accordance with the TNM classification system (UICC 1987). RESULTS: After multivariate analysis, it appeared that the probability of locoregional recurrent disease was increased by (a) T4-stage, (b) high values of the ratio SPF to LI, (c) DNA tetraploidy. Prognostic significance G1PF for SPF, LI, and Tpot was not demonstrated. However, the treatment regimen was not uniform for the total group of 103 patients. In 45 patients treated with radiation as single treatment and in 49 patients treated with postoperative radiotherapy, prognostic significance for G1PF, SPF, LI, and Tpot could not be demonstrated either. Separate statistical analysis was not executed for nine patients, treated by surgery alone. CONCLUSIONS: Prognostic significance could not be demonstrated for Tpot, LI, SPF, and G1PF in our series. The ratio of SPF to LI was found to be a promising prognosticator and is regarded to be indicative for the size of the hypoxic fraction. Prognostic significance for DNA ploidy was confirmed.

Analysis of Variance↗
PubMed1998

Prognostic relevance of cell proliferation markers and DNA-ploidy in gliomas.

The prognostic significance of clinically, histologically and flow cytometrically derived parameters was assessed in 49 glioma patients. With flow cytometry, DNA-index, S-phase fraction (SPF), 5-bromo-2'-deoxyuridine (BrdUrd)-labelling index (LI), and potential doubling time (Tpot) were determined. After univariate analysis of clinical variables such as, age, seizures as initial symptom, and duration of first symptom were found to be significantly associated both with proliferation rate and with local progression free survival (LPFS). Cytomorphological features such as, the presence or absence of mitosis, necrosis, and endothelial proliferation, were separately analysed and appeared to be significantly associated with LPFS. With respect to the cell proliferation markers, we observed a longer LPFS to be associated with a low SPF, a low LI, and a short Tpot. We did not observe a significant association between DNA-ploidy and LPFS. After multivariate analysis both of high and of low grade tumours, we found that neither LI, SPF, nor age had additional prognostic significance for cells in mitoses. We also demonstrated, that necrosis and endothelial proliferation had no additional prognostic significance to that for cells in mitoses. In the subgroup of low grade gliomas, in contrast to high grade gliomas, we noted prognostic significance for LI. We concluded, that i) the presence or absence of cells in mitoses was the strongest single prognosticator in gliomas, ii) in low grade gliomas LI holds prognostic significance.

Brain Neoplasms↗