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S Meijer

Publications and source records attributed to S Meijer.

At least 91 records · Page 5Linked to original sources
PubMed1999

Laparoscopic surgery in the treatment of colonic polyps.

BACKGROUND: Benign colonic polyps that are impossible to remove with the aid of the flexible colonoscope because of their size or location must be removed surgically. METHODS: Twenty patients with colonic adenomatous polyps that could not be resected by colonoscopy because of size or difficult location (n = 18) or polyps in combination with diverticulitis (n = 2) underwent polyp removal through a small 'assisted' incision in the abdominal wall using a standard 'dissection-facilitated' laparoscopic approach to the affected colonic segment. RESULTS: In six patients the polyp was removed through a colotomy, in three through a limited resection (two ileocaecal and one limited sigmoid resection) and in 11 through a standard colectomy (four right hemicolectomy, one left hemicolectomy, four sigmoid and two anterior resections) because of suspicion of cancer. In only one patient could the polyp not be found during laparoscopy, resulting in a second conventional surgical intervention. In four patients carcinoma was diagnosed in the specimen. CONCLUSION: Precise preoperative localization of the polyp and the use of dissection-facilitated laparoscopic colonic surgery make laparoscopic removal of benign colonic polyps an alternative to an open procedure.

Aged↗
PubMed1999

Reliability of intraoperative frozen section and imprint cytological investigation of sentinel lymph nodes in breast cancer.

AIMS: The sentinel lymph node procedure enables selective targeting of the first draining lymph node, where the initial metastases will form. A negative sentinel node (SN) predicts the absence of tumour metastases in the other regional lymph nodes with high accuracy. This means that in the case of a negative SN, regional lymph node dissection is no longer necessary. Besides saving costs, this will prevent many side-effects of lymph node dissection. The aim of this study was to evaluate the reliability of intraoperative cytological and frozen section investigation of the SN to detect metastases. This would allow the axillary lymph node dissection to be performed in the same session as the SN procedure and the excision of the primary tumour in case of a positive SN. METHODS AND RESULTS: Seventy-four SNs were detected by gamma probe detection of nanocolloid and visual localization of Patent Blue accumulations in 54 women with stage T1-2N0M0 invasive breast cancer. The identified SN were immediately investigated by frozen section and imprint cytological investigation. Diagnoses were confirmed on the paraffin material, and in case of negative frozen section and paraffin haematoxylin and eosin sections, skip sections and immunohistochemistry were performed. Thirty-one SNs (42%) contained metastases, of which 27 were detected by the frozen section procedure (sensitivity 87%). There were no false positives (specificity 100%). The sensitivity of the imprints was 62% with a specificity of 100%. When evaluating the data per patient, for the frozen section procedure the sensitivity was 91% and the specificity 100%, and for the imprints, the sensitivity was 63% and the specificity 100%. There were no SNs in which the imprints showed metastases and the frozen section did not. CONCLUSIONS: Intraoperative frozen section analysis is a reliable procedure by which a high percentage of sentinel lymph node metastases can be detected in breast cancer patients without false positive results. This allows the surgeon to perform an immediate axillary lymph node dissection in case of positive SNs. In up to 10% of cases, the final paraffin sections will reveal micrometastases that were not detected by the frozen section, and in these patients axillary lymph node dissection will have to be performed in a second session. The imprint method is significantly less sensitive than the frozen section but may be used as an alternative when frozen section is not possible.

Adult↗
PubMed1999

A prospective randomized study of the systemic immune response after laparoscopic and conventional Nissen fundoplication.

BACKGROUND: Laparoscopic techniques are thought to reduce the postoperative immunologic and metabolic changes of conventional operations. Until now, the only clinical data available were obtained from patients operated on for symptomatic gallstones; moreover, few studies were randomized. This randomized prospective study compares the systemic immune response after laparoscopic and conventional Nissen fundoplication. METHODS: Seventeen patients scheduled for Nissen fundoplication were randomly assigned to undergo either a laparoscopic or a conventional procedure. Postoperative inflammatory response was assessed by measuring the white blood cell count, C-reactive protein, and soluble tumor necrosis factor receptors p55 and p75. Postoperative immune function was assessed by measuring monocyte HLA-DR expression and the stress response was assessed by measuring plasma cortisol concentrations. RESULTS: Laparoscopic surgery resulted in significantly lower plasma CRP levels 1 day after surgery. Both approaches resulted in a significant decrease in HLA-DR expression within 2 hours after surgery. After the laparoscopic approach, postoperative expression was restored to preoperative values within 1 day after surgery. However, after conventional surgery HLA-DR expression remained suppressed and did not return to preoperative values until the fourth postoperative day. No significant differences between the 2 procedures were observed in white cell blood count, sTNFr-p55 and p75, nor in postoperative cortisol levels. CONCLUSIONS: Although both laparoscopic and conventional Nissen fundoplication result in an activation of the systemic immune response, this study suggests that this response could be less after the laparoscopic approach. The differences found may reflect a lower risk for postoperative infective complications.

Adult↗
PubMed1999

Selection of patients for resection of colorectal metastases to the liver using diagnostic laparoscopy and laparoscopic ultrasonography.

OBJECTIVE: To assess the value of diagnostic laparoscopy (DL) and laparoscopic ultrasonography (LUS) in the staging and selection of patients with colorectal liver metastasis. SUMMARY BACKGROUND DATA: Preoperative imaging modalities such as ultrasound, computed tomography, and magnetic resonance imaging are limited in the assessment of the number and exact location of hepatic metastases and in the detection of extrahepatic metastatic disease. Consequently, the surgeon is often faced with a discrepancy between preoperative imaging results and perioperative findings, resulting in either a different resection than planned or no resection at all. METHODS: Fifty consecutive patients were planned for DL and LUS in a separate surgical sitting to assess the resectability of their liver metastases. All patients were considered to be candidates for resection on the basis of preoperative imaging studies. RESULTS: Laparoscopy could not be performed in 3 of the 50 patients because of dense adhesions. The remaining 47 patients underwent DL. On the basis of DL and LUS, 18 (38%) patients were ruled out as candidates for resection. Of the 29 patients who subsequently underwent open exploration and intraoperative ultrasonography, another 6 (13%) were deemed to have unresectable disease. CONCLUSIONS: The combination of DL and LUS significantly improves the selection of candidates for resection of colorectal liver metastases and effectively reduces the number of unnecessary laparotomies.

Adult↗
PubMed1999

Mutagen sensitivity in common cutaneous malignant melanoma and dysplastic naevus syndrome.

Sunlight (ultraviolet radiation) has been identified as the major environmental risk factor for the development of cutaneous malignant melanoma and dysplastic naevi. This is, however, not sufficient to explain all melanoma cases. In recent years much emphasis has been given to genetic susceptibility to melanoma. A biomarker of susceptibility to environmentally related cancer is mutagen sensitivity. This is measured as the number of chromatid breaks in lymphocytes which are exposed to bleomycin in the G2 phase of the cell cycle. It has been described that patients with common melanoma show an increased mutagen sensitivity compared with controls. In the present study mutagen sensitivity was measured in 10 dysplastic naevus syndrome patients and compared with that in 11 patients with common melanoma. We found similar results for common melanoma patients as have been reported earlier: a relatively high mean breaks per cell value (0.93 +/- 0.31). In contrast, melanoma patients with dysplastic naevi showed a significantly (P<0.01) lower mutagen sensitivity value (0.46 +/- 0.34). This phenomenon was even more pronounced when only hereditary dysplastic naevi patients (one or more family members with dysplastic naevi) were considered (n = 5; 0.24 +/- 0.05). These results suggest a difference in the initiation of the carcinogenic process in melanoma with a dysplastic naevus as a precursor and melanoma without dysplastic naevi.

Adolescent↗
PubMed1999

Is major liver surgery associated with an increased systemic inflammatory response? A prospective comparison of hemihepatectomy and other major abdominal surgery.

AIMS/BACKGROUND: Extensive liver resection is associated with a higher morbidity and mortality than other major abdominal surgery. Because the liver is responsible for the clearance of pathogenic particles as well as the clearance and degradation of several inflammatory mediators, the high rate of complications after liver surgery may be due to an enhanced or prolonged inflammatory response. The objective of this prospective study was to investigate whether major liver resection is associated with an enhanced systemic inflammatory response. METHODS: The course of various inflammatory parameters was studied in 12 patients undergoing a hemihepatectomy and the results were compared with those of 12 patients undergoing other major abdominal surgery. RESULTS: After hemihepatectomy, the plasma levels of IL-6, IL-8, sPLA2 and elastase were similar to the levels after other major abdominal surgery, though the hepatectomized patients showed higher levels of lactoferrin, possibly due to impaired hepatic clearance. In addition, the hemihepatectomized patients showed signs of impaired liver function, as was indicated by increased plasma bilirubin and ASAT levels, whereas the other patients did not. CONCLUSIONS: The inflammatory response associated with major liver resection is not significantly different from that after other major abdominal surgery, and therefore does not explain the increased complication rate that is seen after major liver resection. We infer that the most important factor in the development of complications after liver resection may be the hepatic failure itself.

Abdomen↗
PubMed1998

Application of the redox potential for controling a sulfide oxidizing bioreactor

The investigations described show that the formation of elemental sulfur from the biological oxidation of sulfide can be optimized by controling the redox state of the solution. The nonsoluble sulfur can be removed by gravity sedimentation and re-used as a raw material, i.e., in bioleaching processes. It was shown that, by supplying an almost stoichiometrical amount of oxygen to the recirculated gas phase, the formation of sulfate is minimized. The redox potential is mainly determined by the sulfide concentration because this compound has a high standard exchange current density with the platinum electrode surface. By maintaining a particular redox setpoint value, in fact, the reactor becomes a "sulfide-stat." It was shown that in a sulfide-oxidizing bioreactor the measured redox potential, using a polished redox electrode, is kinetically determined rather than thermodynamically. The optimal redox value for sulfur formation is between -147 and -137 mV (H2 reference electrode, 30 degrees C, pH 8). The presented results are currently used for controling several full-scale installations, which desulfurize biogas and high-pressure natural gas. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗
PubMed1998

[The sentinel node procedure: standard intervention for surgical treatment of breast cancer].

Axillary lymph node dissection may be avoided in the surgical treatment of breast cancer if the sentinel node appears to be free of metastatic tumour cells. The sentinel node concept has been validated in hundreds of patients, in whom this node has been localized successfully by dye-guided node mapping and (or) gamma-probe localization after injection of a radiopharmaceutical agent. The success rate of sentinel node localization depends on different factors, such as type, volume and injection site of the radiopharmacon, choice of the handheld gamma-probe, timing of the blue dye injection, and clinical stage of the disease. The combination of preoperative lymphoscintigraphy, intraoperative gamma-probe guidance and blue dye administration will increase the success rate of a sentinel node biopsy. Recent reports, from both Europe and the United States, appear to indicate that the sentinel node biopsy will soon be standard procedure in the surgical treatment of (T1-2) breast cancer. In the majority of breast cancer patients axillary lymph node dissection, a cause of much morbidity, may thus be avoided.

Axilla↗
PubMed1998

Electrophoretic Mobilities of Protein-Coated Hexadecane Droplets at Different pH.

Electrophoretic mobilities of hexadecane droplets in 10 mM potassium phosphate solutions (pH between 3.0 and 7.0) and in phosphate buffered saline (pH 7.0) were measured during adsorption of bovine (BSA) and human (HSA) serum albumin, immunoglobulin G (IgG), and fibrinogen (Fg) from single-protein solutions as well as during protein adsorption from binary HSA/IgG and HSA/Fg mixtures and from diluted plasma. Electrophoretic mobilities became less negative upon adsorption of proteins within 1.5 min after the initiation of adsorption. Only for IgG, was a time-dependent change of the electrophoretic mobilities of the protein-hexadecane complex observed. In phosphate buffered saline, less negative electrophoretic mobilities were measured than in the potassium phosphate solution. Iso-electric points of the protein-hexadecane complexes in 10 mM potassium phosphate were located at pH 5.0 for albumin, at pH 5.5 for Fg, and at pH 6.6 for IgG, i.e., about the iso-electric points of the pure unadsorbed proteins. This confirms that the net charge addition upon protein adsorption, which is positive below the iso-electric point of the proteins, at low protein concentrations determines the effects on the final electrophoretic mobilities of the protein-hexadecane complexes. As a name for the methodology applied, we propose PATH (protein adsorption to hydrocarbons), in analogy to the well-known MATH (microbial adhesion to hydrocarbons) method. The major advantage of PATH is that it represents an in situ method to study protein adsorption, without artifactual rinsing steps, while furthermore the hydrocarbon phase can be replaced by organic solvents to study the role of acid-base interactions in protein adsorption. In combination with drop-shape analysis techniques, PATH also enables us to determine in situ effects of protein adsorption on interfacial tensions. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Localization of regional lymph nodes in melanomas of the head and neck.

OBJECTIVES: To study the efficacy of gamma-probe radiolocalization of the first draining (sentinel) lymph node (SLN) in stage N0 melanoma of the head and neck and to evaluate its potential role in the staging and treatment of this disease. DESIGN: Gamma-probe radiolocalization, a new alternative to blue-dye lymphatic mapping, uses a scintillation (gamma) probe to identify radiolabeled SLNs. In a consecutive sample clinical trial, gamma-probe radiolocalization of the SLN is compared with lymphoscintigraphy and blue-dye lymphatic mapping. Follow-ups ranged from 1.7 years to 4 years, with a mean follow-up of 2.5 years. SETTING: Tertiary and private care teaching hospital. PATIENTS: Between June 1993 and November 1995, 23 patients with stage N0 intermediate-thickness melanoma of the head and neck were enrolled in this volunteer sample. INTERVENTIONS: Twenty-four hours prior to surgery, a radioactive tracer was intradermally injected around the circumference of a primary melanoma. Twelve patients also had blue dye injected just prior to surgical resection. Using a handheld gamma probe, radiolabeled lymph nodes were identified and selectively removed with minimal dissection. In patients with nodes with histologic evidence of metastases, a regional lymphadenectomy was performed. MAIN OUTCOME MEASURES: The successful identification of radiolabeled SLNs, the correlation of SLN radiolabeling to lymphoscintigraphy and blue-dye mapping, and the long-term development of regional metastases. RESULTS: Surgeons successfully resected the radiolabeled SLNs in 22 (96%) of 23 patients. The success rate of blue-dye lymphatic mapping was 8 (75%) of 12 patients and lymphoscintigraphy was 20 (91%) of 22 patients. One hundred percent of blue-stained lymph nodes were radiolabeled. The one patient in whom no SLN could be identified developed regional disease at 17 months. CONCLUSIONS: Gamma-probe radiolocalization and resection of the radiolabeled SLN is a simple and reliable method of staging regional lymph nodes and determining the need for elective lymphadenectomy.

Adult↗
PubMed1998

Renal toxicity of the anticancer drug fostriecin.

PURPOSE: Fostriecin is an inhibitor of topoisomerase II catalytic activity. In a phase I trial we observed renal toxicity, documented as a rise in serum creatinine, which was reversible and non-dose-limiting. The purpose of this study was a detailed analysis of this toxicity. METHODS: A total of 20 patients received fostriecin as a 1-h i.v. infusion daily x 5 at doses ranging from 2 to 20 mg/m2 per day. Serum creatinine determination and urinalysis were performed daily during drug administration. Renal hemodynamics were measured by means of clearance studies using 125I-iothalamate and (131)I-hippuran in eight patients at doses of > or =4 mg/m2 per day at baseline, on day 3 or 4 during the first course, and 3 weeks after the second course. RESULTS: The rise in serum creatinine was maximal after one to two doses despite continued administration. This increase showed no correlation with the dose level at fostriecin doses of > or =4 mg/m2 per day. Urinary beta2-microglobulin concentrations increased 150-fold (median), which is compatible with impaired tubular reabsorption. The median change in the glomerular filtration rate (GFR) was -36% (range -28% to -44%), that in effective renal plasma flow (ERPF) was -23% (range -11% to -36%), and the filtration fraction (FF) decreased in all patients during the first course of treatment. The values measured 3 weeks after the second course, however, did not differ from baseline. CONCLUSIONS: Fostriecin induces reversible renal hemodynamic changes compatible with renal tubular damage.

Adult↗
PubMed1998

Effects of gemcitabine on renal function in patients with non-small cell lung cancer.

Gemcitabine is a novel fluorine-substituted cytarabine (Ara-C) analogue with activity against a range of solid tumours. Besides dose-limiting haematological toxicity, renal side-effects were observed from phase I and II studies concerning elevations of serum creatinine, proteinuria and erythrocyturia. The aim of this study was to investigate the effect of gemcitabine on renal function in 11 untreated patients with non-small cell lung cancer (NSCLC). Gemcitabine was given as weekly infusions of 1250 mg/m2 for 3 weeks, followed by 1 week rest. This comprised one cycle (maximum of six cycles). The glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured simultaneously with a constant infusion of 125I-iothalamate and 131I-hippuran, respectively. Tubular damage was monitored by excretion of tubular enzymes (lactic dehydrogenase (LDH), alkaline phosphatase (ALP), gamma-glutamyltransferase (GT) and beta 2-microglobulin); glomerular damage was monitored by excretion of albumin in the urine. In 9 patients, the effect of the first infusion was evaluated. After the first infusion of gemcitabine, no change was observed in renal function. After two, three, and six cycles of treatment, no significant changes in GFR and ERPF were noticed in 9 evaluable patients. However, in 3 patients, a decrease in GFR of > 10% was observed after multiple cycles. In one of them this was accompanied with albuminuria (360 mg/24 h) and erythrocyturia. There were no significant changes in urinary excretion of tubular enzymes or albumin. In conclusion, we did not observe acute renal toxicity with gemcitabine. No significant cumulative effects of gemcitabine on renal function could be detected, although 3 patients, treated with multiple cycles of gemcitabine, showed a moderate decrease in renal function. Glomerular damage might play a role in the development of renal function loss.

Adult↗
PubMed1998

Sentinel lymph node biopsy in breast cancer: guidelines and pitfalls of lymphoscintigraphy and gamma probe detection.

BACKGROUND: Sentinel node (SN) biopsy appears to offer an alternative to routine axillary lymph node dissection (ALND) for staging patients with breast cancer. Various techniques have been studied for identifying the SN, using vital blue dye or radioactive colloid, and initial reports are promising. The inherent limitations and pitfalls must be clearly understood before SN biopsy can be implemented in dinical practice. STUDY DESIGN: In a prospective trial, the feasibility of using lymphoscintigraphy and gamma probe detection for performing SN biopsy was studied. In 130 consecutive patients with T1-T2, N0 breast cancer, preoperative lymphoscintigraphy was performed with technetium 99m-colloidal albumin. During ALND, the radioactive axillary SNs were localized by the gamma probe. Histopathologic examination of the harvested SNs was compared with the status of the axillary lymph nodes. RESULTS: Axillary focal accumulations were clearly identified on lymphoscintigraphy in 116 patients (89%). The failure rate was significantly higher in patients who had a previous excision biopsy (36%) than in those with a palpable tumor in situ (4%). Using the gamma probe, radiolabeled axillary SNs were successfully biopsied in 122 patients (94%). Because 18 of these patients did not undergo formal lymphadenectomy, the predictive accuracy of SN biopsy was analyzed in 104 patients. Radioactive nodes revealed metastases in 44 of 104 patients (42%); in 26 of them (59%), these were the only involved axillary nodes. The SN was negative in 60 patients (58%); in one patient the ALND was found to contain metastatic disease (1.7% false negatives). Biopsy of the SN was 98% accurate in predicting the absence of nodal metastases. CONCLUSIONS: There are certain guidelines for performing SN biopsy by lymphoscintigraphy and gamma probe detection. Success depends primarily on an adequate functional capacity of the SN, necessary for sufficient nodal uptake to ensure accurate identification. Lymphoscintigraphy defines the pattern of lymph flow and may prevent failure or false-negative biopsies. Biopsy of the SN is a highly accurate, minimally invasive method of staging patients with breast cancer and can substantially reduce the morbidity and costs of surgical treatment by avoiding unnecessary ALND in the majority of patients.

Axilla↗
PubMed1998

Chemokines produced by mesothelial cells: huGRO-alpha, IP-10, MCP-1 and RANTES.

Recently we showed the in vivo relevance of chemokines in cases of bacterial peritonitis in continuous ambulatory peritoneal dialysis (CAPD) patients. Mesothelial cells, the most numerous cells in the peritoneal cavity, are hypothesized to function as a main source of chemokine production. We investigated the time- and dose-dependent expression patterns of four chemokines by mesothelial cells at the mRNA and protein level in response to stimulation with physiological doses of proinflammatory mediators that are present at the site of bacterial inflammation. Besides the chemokines huGRO-alpha (attractant for neutrophils), MCP-1 and RANTES (monocyte attractants), the expression and production of IP-10 was analysed. Mesothelial cells were cultured and stimulated with either IL-1beta, tumour necrosis factor-alpha (TNF-alpha) or IFN-gamma or combinations of these. The time- and dose-dependent mRNA expression of the chemokines was determined by Northern blot analysis and the protein production by ELISA. It was concluded that mesothelial cells could indeed be triggered by the mentioned stimuli to induce mRNA and protein production (huGRO-alpha and IP-10) or to augment constitutive protein production (MCP-1). However, RANTES mRNA and protein production could only be induced in some cases and only in small amounts. The chemokine response of mesothelial cells was regulated differentially, depending on the stimulus and the chemokine measured. In distinct cases, combination of the stimuli led to synergy in mRNA expression and protein production. The presented in vitro data support our hypothesis that mesothelial cells in vivo are the main source of relevant chemokines in response to proinflammatory mediators, suggesting an important role for mesothelial cells in host defence.

Cells, Cultured↗
PubMed1998

Transport and retention of colloidal tracers in regional lymphoscintigraphy in melanoma: influence on lymphatic mapping and sentinel node biopsy.

Sentinel node (SN) biopsy is a staging technique used to select patients for regional lymphadenectomy in melanoma. We compared the two most widely used radioactive tracers, 99mTc-colloidal albumin (99mTc-CA) and 99mTc-sulphur colloid (99mTc-SC), with respect to scintigraphy, success rate in gamma probe guided biopsy and absolute uptake in the SN. Scintigraphy was performed in six volunteers after simultaneous injection of the respective tracers in each leg. Comparison of uptake of both tracers showed a higher uptake on the 99mTc-CA side. The scintigraphic count ratio of SNs labelled with 99mTc-SC compared with 99mTc-CA was 1 to 9 28. Next, 20 patients with biopsy-proven melanoma were randomized for injection of 99mTc-CA or 99mTc-SC followed by SN biopsy. Within 20 min after the injection, focal uptake was seen in all cases of the 99mTc-CA group but in only seven of the 10 patients in the 99mTc-SC group (P < 0.05). Focal accumulations were seen in all patients of both groups after 2 h. Spill to non-SNs was seen in five of the 99mTc-CA patients and three of the 99mTc-SC patients. In all patients the SNs could be retrieved under the guidance of a gamma probe and blue dye. The uptake in the SN was significantly higher (P < 0.001) after the injection of 99mTc-CA (0.92+/-0.40%) compared with 99mTc-SC (0.34+/-0.34%). When dynamic scintigraphy is performed, 99mTc-CA is preferable. SN uptake of 99mTc-SC is less than that of 99mTc-CA but this does not adversely affect the surgical procedure.

Adult↗