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Biomedical subjects

J de Vries

Publications and source records attributed to J de Vries.

At least 37 records · Page 2Linked to original sources
PubMed2004

Axillary recurrence after sentinel lymph node biopsy.

UNLABELLED: Sentinel lymph node biopsy (SLNB) without further axillary dissection in patients with sentinel node-negative breast carcinoma appears to be a safe procedure to ensure locoregional control. During a median follow-up of 35 months the false-negative rate was 1% in our study population of 185 patients. BACKGROUND: The objective of this prospective study is to provide data on follow-up of patients with primary operable breast carcinoma staged with SLNB without axillary lymph node dissection (ALND) if the sentinel lymph nodes (SLNs) were tumour-negative. METHODS: One hundred and eighty-five patients were enrolled. Preoperative dynamic and static lymphoscintigraphy were performed; both a vital blue dye and a gamma detection probe were used intraoperatively. Patients with tumour-positive SLNs received completion ALND or if no SLNs could be identified. All patients were monitored according to regional follow-up protocols. RESULTS: The SLNs were identified in 179 out of the 185 patients. In 73 patients the SLNs were tumour-positive and in 106 patients tumour-negative. The median follow-up was 35 months (range 17-59). In one SLN-negative patient an axillary recurrence occurred 26 months after the SLNB (false-negative rate: 1%). CONCLUSIONS: SLNB without ALND appears to be a safe procedure to ensure locoregional control in SLN-negative breast carcinoma, if carried out by an experienced team.

Adult↗
PubMed2003

Charge driven fragmentation of nucleobases.

We studied multiple ionization of single nucleobases by means of slow highly charged ions (Xe(q+), q=5-25). The products of the subsequent fragmentation were studied using high resolution coincidence time-of-flight spectrometry. We observed a strong dependence of the fragment kinetic energies on the initial charge state of the intermediate parent ions as well as on the initial chemical environment of the respective fragment ions within the parent molecule. The data allow us to shed light on the charge distribution within the molecule as well as on the fragmentation dynamics of these intermediate size systems.

DNA Damage↗
PubMed2003

Multiple surface properties of worn RGP lenses and adhesion of Pseudomonas aeruginosa.

The aim of this study is to determine rigid gas permeable (RGP) lens surface properties prior to and after wear that are influential on adhesion of Pseudomonas aeruginosa. After 10 and 50 days of wear and after end-stage use, lenses were collected for determination of physico-chemical surface properties and bacterial adhesion in a parallel plate flow chamber. Water contact angles on unused RGP lenses amounted 47+/-13 degrees and were affected by wear. In addition, %O at the lens surfaces, as determined by X-ray photoelectron spectroscopy increased after use for 10 and 50 days, but decreased after end-stage wear. The %N hardly increased after wear and, in line, SDS-PAGE did not indicate adsorbed proteins. The surface roughness of the lenses, as measured by atomic force microscopy amounted 9 nm after 10 and 50 days of use, but end-stage lenses were significantly rougher (48+/-23 nm). Moreover, initial deposition of P. aeruginosa #3 increased with increasing roughness for end-stage lenses. Multiple regression analysis, however, revealed that both physical and chemical surface properties were predictive for initial bacterial deposition to lens surfaces. After 10 days of wear, bacterial deposition was governed by the water contact angle, surface roughness, %O, %N, and %Si, while after 50 days of wear the surface roughness, %N, and %Si were found predictive for bacterial deposition. Initial bacterial deposition to end-stage lenses was solely dependent on the surface roughness. Summarizing, physico-chemical surface properties of RGP lenses change slightly during the first 10-50 days of wear, but end-stage lenses all had increased surface roughness, concurrent with increased bacterial adhesion.

Bacterial Adhesion↗
PubMed2003

The influence of mental fatigue on facial EMG activity during a simulated workday.

The present study investigated whether facial EMG measures are sensitive to the effects of fatigue. EMG activity of the corrugator and frontalis muscles was recorded during and after a simulated workday. Fatigue was evaluated in four ways: (a) the building up of fatigue effects during the workday, (b) the building up of fatigue during a test period, (c) examination of after-effects of the workday in two test sessions in the evening, and (d) comparison of subjects with a high-and low-score on an Emotional Exhaustion questionnaire. EMG activity decreased during the workday and increased again in the evening. EMG activity also increased during a test period, reflecting increased mobilization to maintain performance. High-score subjects showed a lower level of EMG activity throughout the entire workday. They reported a higher need for recovery, experienced the workday as more fatiguing, and were less well rested when getting up. EMG measures seem to reflect that high-score subjects have problems with investing sufficient energy to maintain performance during a workday.

Adult↗
PubMed2003

The influence of a hexametaphosphate-containing chewing gum on the wetting ability of salivary conditioning films in vitro and in vivo.

OBJECTIVE: Adsorbed conditioning films of salivary components on dental enamel surfaces or pellicles form the interface between teeth and the oral environment. The wetting ability of salivary conditioning films dictates biological adhesion phenomena such as plaque formation, calcification and staining, and also influences mouth perception through effects on lubricity. This study assessed the effects of hexametaphosphate release from a chewing gum matrix on the wetting ability of salivary conditioning films in vitro and in vivo. METHODOLOGY: Results obtained for hexametaphosphate chewing gum were compared with those produced by hexametaphosphate-containing dentifrice, which has been clinically proven to have efficacy for stain removal and prevention and dental calculus prevention. RESULTS: Contact angle assessments revealed that hexametaphosphate dentifrice produced markedly hydrophilic conditioning films in vitro. Hexametaphosphate chewing gums had only minor effects on surface contact angles in vitro. However, in vivo intra-oral contact angle measurements on tooth surfaces in volunteers showed that both hexametaphosphate dentifrice and chewing gum produced more hydrophilic tooth surfaces. CONCLUSION: These results support the activity of hexametaphosphate on tooth surfaces delivered both from dentifrice and chewing gum forms.

Adhesiveness↗
PubMed2002

[Endoscopic adrenal surgery: a new standard in 10 years].

OBJECTIVE: Description of the development of endoscopic adrenal surgery and the introduction of this procedure in Groningen University Hospital (GUH) and in the rest of the Netherlands. DESIGN: Literature overview, description of own results and results of a national survey. METHOD: Medline was searched with the search terms: 'laparoscopic', 'endoscopic' and 'adrenalectomy' for the period 1992-2001. During the period January 1998-July 2001, 39 patients underwent adrenal surgery at the GUH. A questionnaire about adrenal surgery was sent to 41 Dutch hospitals which provide surgical training. RESULTS: A total of 37 literature references were found, mostly prospective studies with a maximum of 130 patients, sometimes in retrospective comparison with conventional open surgery. No randomised studies were found. In the patient group at the GUH, 32 of the 39 patients had the adrenal gland removed endoscopically (82%). There were 3 (8%) primary open procedures due to tumour size (mean: 13 cm) and 4 (11%) conversions (mean tumour size: 6 cm). After 32 procedures, there was still a trend towards a shorter operation time. The response to the national survey was 88% (36/41). In 9% of the hospitals no adrenal surgery was performed. In the remaining hospitals minimally invasive adrenal surgery took place in about two-thirds of the patients, mainly via the retroperitoneal route (63%). More procedures were carried out in the university hospitals (mean: 11.6 per year) than in the non-university hospitals (mean: 2.9 per year). There were few concrete arrangements concerning the concentration of this technically demanding and rare procedure. CONCLUSION: Over the last 10 years endoscopic adrenalectomy has developed to become the new standard for the surgical removal of benign adrenal tumours with a diameter < 10 cm. Although the procedure has an evident learning curve, there are still few concrete arrangements in the Netherlands concerning the necessary concentration of this difficult and rare technique.

Adrenal Gland Neoplasms↗
PubMed2002

Quantitative assessment of calf circumference in Duchenne muscular dystrophy patients.

Duchenne muscular dystrophy is clinically characterised by progressive muscle weakness and a gradual increase in the size of some affected muscles, especially calf muscles. The extent of calf enlargement is usually determined by subjective visual assessment. The purpose of this study was to determine the extent of calf muscle enlargement in Duchenne muscular dystrophy (DMD) patients compared with healthy age matched boys by quantifying calf circumference. Calf circumference in the group of DMD patients is significantly increased. However, in individual patients calf enlargement can be feigned by a discrepancy between calf circumference and circumference of the upper leg and arm muscles as part of a general muscle atrophy.

Case-Control Studies↗
PubMed2002

Surgical revision of filtration blebs: a follow-up study.

PURPOSE: To assess the clinical outcome of one technique for surgical revision of filtration blebs in terms of bleb function and intraocular pressure control. METHODS: Retrospective analysis of 36 consecutive cases of leaking, overfiltrating, or oversized blebs treated with bleb excision and conjunctiva and Tenon advancement in a glaucoma referral center between January 1991 and December 1999. Surgical success was defined as a final intraocular pressure between 6 and 22 mm Hg with or without topical antiglaucoma medication, resolution of the bleb leak, hypotony maculopathy and symptoms, and no need for repeat glaucoma surgery. RESULTS: With a minimum of 12 months and an average of 29.5 months of follow-up, the overall success rate was 86.1%, with 51.6% of patients not requiring medication. In the success group, mean (SD) intraocular pressure was 23.7 (5.9) mm Hg before the original trabeculectomy, 4.3 (3.7) mm Hg prior to revision surgery, and 13.5 (SD 3.8) mm Hg at the last follow-up visit after the revision surgery. Mean number of antiglaucoma medications was 2.1 (range, 1-4) before the original trabeculectomy, none before the revision surgery, and 0.8 (range, 0-3) at the last follow-up visit. CONCLUSIONS: The surgical revision technique offers a definitive solution for most of these bleb complications and a satisfactory intraocular pressure control in the majority of patients.

Adult↗
PubMed2001

The release of noradrenaline in the locus coeruleus and prefrontal cortex studied with dual-probe microdialysis.

The present study was undertaken to investigate and compare the properties of noradrenaline release in the locus coeruleus (LC) and prefrontal cortex (PFC). For that aim the dual-probe microdialysis technique was applied for simultaneous detection of noradrenaline levels in the LC and PFC in conscious rats. Calcium omission in the LC decreased noradrenaline levels in the LC, but increased its levels in the PFC. Novelty increased noradrenaline levels in both structures. Infusion of the alpha(2)-adrenoceptor agonist clonidine decreased extracellular noradrenaline in the LC as well as in the PFC. Infusion of the alpha(2A)-adrenoceptor antagonist BRL44408, or the alpha(1)-adrenoceptor agonist cirazoline into the LC or PFC caused a similar dose-dependent increase in both structures. When BRL44408 or cirazoline were infused into the LC, few effects were seen in the PFC. Infusion of the 5-HT(1A)-receptor agonist flesinoxan into the LC or the PFC decreased the release of noradrenaline in both structures. When flesinoxan was infused into the LC, no effects were seen in the PFC. When the GABA(A) antagonist bicuculline was applied to the LC, noradrenaline increased in the LC as well as in the PFC. It is concluded that the release of noradrenaline from somatodendritic sites and nerve terminals responded in a similar manner to presynaptic receptor modulation. The possible existence of dendritic noradrenaline release is discussed.

Adrenergic alpha-Agonists↗
PubMed2001

The natural transformation of the soil bacteria Pseudomonas stutzeri and Acinetobacter sp. by transgenic plant DNA strictly depends on homologous sequences in the recipient cells.

The nptII(+) gene present in the genome of transgenic potato plants transforms naturally competent cells of the soil bacteria Pseudomonas stutzeri and Acinetobacter BD413 (both harboring a plasmid with an nptII gene containing a small deletion) with the same high efficiency as nptII(+) genes on plasmid DNA (3x10(-5)-1x10(-4) transformants per nptII(+)) despite the presence of a more than 10(6)-fold excess of plant DNA. However, in the absence of homologous sequences in the recipient cells the transformation by nptII(+) dropped by at least about 10(8)-fold in P. stutzeri and 10(9)-fold in Acinetobacter resulting in the latter strain in < or =1x10(-13) transformants per nptII(+). This indicated a very low probability of non-homologous DNA fragments to be integrated by illegitimate recombination events during transformation.

Acinetobacter↗
PubMed2001

Contralateral reinnervation of midline muscles in facial paralysis.

We report on a patient with recovery of activity of the left orbicularis oris and nasalis muscles 3 months after a complete left facial palsy. Stimulation of the affected facial nerve evoked no responses, whereas contralateral facial nerve stimulation showed polyphasic responses with very long latencies in the nasalis and orbicularis oris muscles. Needle electromyography (EMG) revealed abnormal spontaneous activity in the left orbicularis oris muscle. The motor unit action potentials on the left side of the face could be recruited only during marked contraction of the corresponding muscles on the right and were of low voltage and polyphasic ("nascent potentials"). Contralateral reinnervation is probably due to sprouting of terminal branches crossing the midline of the face and innervating bundles of muscle fibers on the affected side. This phenomenon seems unfamiliar to most clinicians. Whether the activity is due to conduction along nerve fibers or muscle fibers crossing the midline is discussed.

Adult↗
PubMed2001

Employment status, job characteristics, and work-related health experience of people with a lower limb amputation in The Netherlands.

OBJECTIVES: To describe the occupational situation of people with lower limb amputations in The Netherlands and to compare the health experience of working and nonworking amputee patients with a nonimpaired reference population. DESIGN: Cross-sectional study in which patients completed a questionnaire about their job participation, type of job, workplace adjustments to their limb loss, their position in the company, and a general health questionnaire. SETTING: Orthopedic workshops in The Netherlands with a population of lower limb amputees. PATIENTS: Subjects were recruited from orthopedic workshops in the Netherlands. They ranged in age from 18 to 60 years (mean, 44.5yr) and had a lower limb amputated at least 2 years (mean, 19.6yr) before this study. MAIN OUTCOME MEASURES: A self-report questionnaire, with 1 part concerning patient characteristics and amputation-related factors, and the other concerning job characteristics, vocational handicaps, work adjustments, and working conditions; and a general health questionnaire (RAND-36) to measure health status. RESULTS: Responses were received from 652 of the 687 patients (response rate, 95%) who were sent the questionnaire. Sixty-four percent of the respondents were working at the time of the study (comparable with the employment rate of the general Dutch population), 31% had work experience but were not presently working, and 5% had no work experience. After their amputations, people shifted to less physically demanding work. The mean delay between the amputation and the return to work was 2.3 years. Many people wished their work was better adjusted to the limitations presented by their disability and they mentioned having problems concerning possibilities for promotion. Seventy-eight percent of those who stopped working within 2 years after the amputation said that amputation-related factors played a role in their decision. Thirty-four percent said that they might have worked longer if certain adjustments had been made. The health experience of people who were no longer working was significantly worse than that of the working people with amputations. CONCLUSIONS: Although amputee patients had a relatively good rate of job participation, they reported problems concerning the long delay between amputation and return to work, problems in finding suitable jobs, fewer possibilities for promotion, and problems in obtaining needed workplace modifications. People who had to stop working because of the amputation showed a worse health experience than working people.

Adult↗