PubMed Health⌕ Search

Biomedical subjects

J van Aken

Publications and source records attributed to J van Aken.

At least 19 recordsLinked to original sources
PubMed2005

Comparison of long term outcome of patients with rheumatoid arthritis presenting with undifferentiated arthritis or with rheumatoid arthritis: an observational cohort study.

BACKGROUND: The outcome of undifferentiated arthritis (UA) ranges from remission to rheumatoid arthritis (RA) fulfilling the American College of Rheumatology (ACR) classification criteria. OBJECTIVES: To report the outcome of UA after 1 year of follow up and compare the disease course of patients who presented with UA, but evolved into RA within 1 year (UA-RA group), with that of patients who presented with RA fulfilling the ACR criteria (RA-RA group). METHODS: The diagnosis of 330 patients who presented with UA was recorded at 1 year. The UA-RA and RA-RA groups were then followed up for 3 more years. Outcome measurements were radiographic progression, disease activity, and functional capacity. RESULTS: From 330 patients who were diagnosed UA, 91 had evolved into RA at 1 year; 62 patients had presented with RA. No significant differences were detected between the UA-RA and RA-RA groups in median Sharp/van der Heijde score at baseline, radiographic progression rates, disease activity, and functional capacity. However, significantly more disease modifying antirheumatic drugs were prescribed in the RA-RA group. CONCLUSION: The disease outcome of patients who present with UA that evolves into RA within 1 year is the same as that of patients who present with RA as measured by radiographic progression, disease activity, and functional capacity.

Adult↗
PubMed2004

Radiological outcome after four years of early versus delayed treatment strategy in patients with recent onset rheumatoid arthritis.

OBJECTIVE: To determine the effect of different treatment strategies (early versus delayed) on the radiological progression of joint damage during 4 years. Additionally, to determine the effect of treatment strategy on the association of HLA class II alleles and joint damage. METHODS: Progression of radiographic damage and association of radiographic damage and genetic predisposition were compared in two cohorts, one treated according to the delayed treatment strategy (initial treatment with analgesics), the other treated according to the early treatment strategy (treatment with disease modifying antirheumatic drugs (DMARDs) chloroquine or sulfasalazine). Radiographic damage was measured by the modified Sharp-van der Heijde method. Genetic predisposition was determined by high resolution HLA-DR and DQ typing. RESULTS: A completers-only analysis of 153 patients (originally 206 patients) in a non-randomised design showed less radiographic progression from 0 to 4 years in the early treatment group (median Sharp progression rate 1.3 points/year, n = 75) than in the delayed treatment group (2.5 points/year, n = 78) (p = 0.03). The progression from 1 to 4 years did not differ significantly between the groups. At 4 years, joint destruction in both groups was positively correlated with the presence of the shared epitope. CONCLUSIONS: The beneficial effect of early DMARD treatment on the radiological progression of joint damage is still present at 4 years. However, the rate of joint destruction from 1 to 4 years did not differ between the delayed and early treatment group. Neither the radiographic nor the immunogenetic data suggest that longlasting disease modification has been induced by early treatment.

Adult↗
PubMed2003

Cardiovascular changes during endoscopic third ventriculostomy.

During an endoscopic third ventriculostomy (ETV) a sudden increase in intracranial pressure (ICP) may occur at any time. In the literature little attention has been paid to the early detection of such an increase. In particular the occurrence of a 'Cushing reflex' has not been discussed in this context. Therefore, we have now analysed retrospectively the anesthesia charts of 88 patients with obstructive hydrocephalus who had undergone ETV under general anesthesia. Monitoring included invasive blood pressure, electrocardiogram, end-expired carbon dioxide, pulse oximetry and heart rate. These variables were now evaluated before and after the introduction of the endoscope and during and after the occurrence of any change. In 67 patients the procedure had been uneventful. In 6 patients the occurrence of tachycardia and hypertension followed by bradycardia and hypertension was clearly the result of an increase in ICP, which we call a Cushing reflex. In his classical description of this pressure response Cushing reported the occurrence of hypertension, bradycardia and apnoea. However, many investigators have shown that beside systemic hypertension, both tachycardia and bradycardia are essential components of the Cushing reflex. Waiting for a persistent bradycardia to alert the surgeon during ETV can allow a fatal asystole.

Adolescent↗
PubMed1998

[Tuberculosis of the larynx].

Laryngeal tuberculosis was diagnosed in two men, a 73-year-old man Dutch by birth and a 40-year-old one Turkish by birth. In the former patient it was probably primary tuberculosis, in the latter secondary (he had lung tuberculosis as well). The clinical picture was highly suggestive of laryngeal carcinoma in both patients. They both recovered with chemotherapy. Laryngeal tuberculosis may mimic laryngeal carcinoma. The diagnosis is based on Ziehl-Neelsen staining, culture and polymerase chain reaction (PCR) on Mycobacterium tuberculosis. Because laryngeal tuberculosis is highly infectious, the patient has to be nursed in isolation and people in his or her environment have to be screened. The response of laryngeal tuberculosis to chemotherapy is good.

Adult↗
PubMed1997

Fever attributed to the use of hydroxyurea.

We report on three patients who developed fever after starting treatment with the anti-neoplastic agent, hydroxyurea. Fever occurred within 5 days to 3 weeks after starting treatment. In all cases the causal relationship between fever and use of hydroxyurea was demonstrated by spontaneous recovery after drug withdrawal and was confirmed by recurrence of fever after rechallenge. Other causes were excluded. Fever was accompanied by rash, gastro-intestinal and pulmonary symptoms, and arthralgia. Physicians should be aware of the fact that unexplained fever may be caused by hydroxyurea.

Aged↗
PubMed1996

Tip-localized calcium entry fluctuates during pollen tube growth.

Studies have been conducted on the dynamics of Ca2+ entry in pollen tubes using ratiometric ion imaging to measure the intracellular gradient and an ion selective vibrating electrode to detect the extracellular influx. A steep tip-focused gradient occurs in all species examined, including Lilium longiflorum, Nicotiana sylvestris, and Tradescantia virginiana. Anlaysis of Lilium pollen tubes loaded with dextran conjugated fura-2 reveals that the gradient derives from Ca2+ entry that is restricted to a small area of plasma membrane at the extreme apex of the tube dome. Since the apical membrane is continually swept to the flanks during tube elongation, either Ca2+ channels are specifically retained at the extreme apex or, as seems more likely, the Ca2+ channels which were active at the tip rapidly inactivate, as new ones are inserted during vesicle fusion. Ratiometric imaging further indicates that the high point of the gradient fluctuates in magnitude from 0.75 to above 3 microM, during measuring intervals of 60 sec, with the elevated points being correlated with an increased rate of tube growth. Independent analysis of the growth at 2- to 3-sec intervals reveals that the rates can fluctuate more than threefold; tubes longer than 700 mu m exhibit oscillations with a period of 23 sec, while tubes shorter than 700 mu m display erratic fluctuations. Inhibition of pollen tube growth caused by mild temperature shock or caffeine (1.5 to 3.0 mM) is correlated with the dissipation of the tip-focused gradient and the Ca2+ influx. Recovery from both treatments is denoted by a global swelling of the pollen tube tip, concomitant with a high transient entry of Ca2+ in the tip. The location of the highest Ca2+ domain within the tip region defines the point from which normal cylindrical elongation will proceed.

Caffeine↗
PubMed1994

[Poisoning with amitraz, an agricultural anti-ectoparasitic agent].

A mentally handicapped male aged 22 years ingested 25-100 ml of the agricultural anti-ectoparasite product amitraz (Taktic) (at most 12.5 g amitraz), and went into coma approx. one hour later (Glasgow coma score: 3). Gastric lavage was performed and activated charcoal and sodium sulphate deposited in the stomach. Product information could be obtained from the manufacturers in the United Kingdom with some trouble, 1.5 hours after admission. It was striking how little information is available concerning the toxicity of agricultural products. Patient had recovered the next day; he was discharged three days after admission. Blood assay 1.5 hours after ingestion revealed a concentration of amitraz plus metabolites of 3.7 micrograms/ml; when the patient came out of coma it was < 0.67 microgram/ml.

Adult↗
PubMed1994

A large intracranial xanthoma in familial hypercholesterolemia.

Intracranial xanthomata occurring in patients with familial hypercholesterolemia are very rare. We present a young woman with a large intracranial xanthoma. The patient was treated for a familial hyperlipoproteinemia type IIa. MRI and morphological features are shown and discussed on reviewing the literature.

Adult↗
PubMed1993

Time-related changes of in vivo projection errors in standardized radiographs.

Subtraction radiography requires radiographs made with identical projection geometry. Recently a new radiographic aiming device and an x-ray beam manipulator made it possible to repeat radiographic exposures in vivo with small angular errors and to measure the angular errors occurring. The purpose of the present investigation was to study in vivo the measuring error and the angular errors produced by this new method at different time points (0, 6, and 12 months) and to assess the effect of different time intervals between exposures (0, 6, and 12 months). Ten sites were investigated. At each time point 2 exposures were made, resulting in 6 radiographs per site. For each pair of radiographs the measuring errors occurring during analysis and the projection errors were determined for each time point and for each time interval. Friedman's test and t-test were used to evaluate the errors. A difference in the measuring error of the system and in the angular errors at the time points 0, 6, and 12 months could not be detected. A time interval between exposures also did not have an effect on the measuring error. Time did not affect the vertical and horizontal angular errors measured between the radiographs producing the smallest oblique error. A combination of radiographs producing the largest oblique angular error showed an increase of the horizontal and vertical angular errors when the time interval increases. These effects, however, were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Dose distribution in tissues].

Biological effects of ionising radiation are dependent on the distribution of doses in tissue. In this article parameters influencing the distribution of dose in tissue are discussed with emphasis on intraoral and rotational panoramic radiography. For both examinations the probability to develop stochastic effects is estimated. For intraoral radiography the probability ranges from 0.1 to 0.3 per million exposures and for rotational panoramic radiography from 0.4 to 0.8 per million. For the whole Dutch population the probability to develop stochastic effects is 0-2 persons per year and 0-1 person per year respectively. Dental radiography is therefore justified if further diagnostic information is to be expected and exposure circumstances are optimal.

Dose-Response Relationship, Radiation↗
PubMed1991

Absorbed dose to organs in the head and neck from bitewing radiography.

Dose measurements were carried out to estimate the absorbed dose to organs at risk from bitewing radiography under exposure conditions similar to those found in general dental practice in The Netherlands. The measurements were carried out in the head and neck of a Rando phantom using TLD-100 ribbons. Three different X-ray machines were used simulating 10 different exposure conditions to determine the effects of beam energy, beam size and focus-skin distance on the absorbed dose. The absorbed dose in the primary beam, close to the focal spot, decreased as the beam energy increased, while behind the film plane it increased with the beam energy. Outside the primary beam, at short distances from the skin surface, the absorbed dose decreased as the energy increased, while behind the film plane and at greater distances from the primary beam the absorbed dose increased as the beam energy increased. The absorbed dose was significantly lower for smaller beam sizes and for larger focus-skin distances, independent of beam energy.

Bone Marrow↗
PubMed1991

Risk assessment from bitewing radiography.

The effective dose equivalent and the effective dose from bitewing radiography have been estimated for three different X-ray sets under 10 different exposure conditions using the ICRP 26 (1977) and the ICRP 60 (1990) recommendations. The results of dose measurements in the head and neck with an Alderson Rando phantom and thermoluminescence dosimeters (TLD-100 ribbons) were used (Velders XL et al. Dentomaxillofac Radiol 1991; 20: 161-5). The effective dose equivalent (ICRP 26) was calculated using the salivary glands and brain as remainder organs. The highest effective dose equivalent was 11 microSv for the Philips Oralix 50 unit with a round, pointed cone; the lowest was 2 microSv for the X-ray sets with a rectangular open-ended tube. The highest effective dose using the ICRP 60 weighting factors was 4 microSv for the Oralix 50, the lowest 1 microSv for the X-ray sets with a rectangular open-ended tube. The probability of stochastic effects was calculated as at the most 0.18 x 10(-6) using a nominal probability coefficient of 165 x 10(-4) Sv-1 (ICRP 26); when using the ICRP 60 recommendations (where the nominal probability coefficient for stochastic effects including non-fatal cancer is 730 x 10(-4) Sv-1) the maximum probability was 0.25-0.31 x 10(-6). The maximum probability of fatal cancer induction was calculated as 0.18 x 10(-4) for both fatal probability coefficients, 125 x 10(-4) Sv-1 in ICRP 26 and 500 x 10(-4) Sv-1 in ICRP 60. The calculated probability of the total stochastic effects is nearly twice as high when using the new recommendations, whilst the estimated probability of fatal cancer induction is of the same order of magnitude with both.

Dose-Response Relationship, Radiation↗
PubMed1991

In vivo determination of radiographic projection errors produced by a novel filmholder and an x-ray beam manipulator.

Subtraction radiography requires radiographs made with identical projection geometry. The purpose of the present investigation was to develop and evaluate a new in vivo method to measure angular radiographic projection error. This included the development of a system for accurate control of the x-ray beam angulation relative to the intraoral film and the evaluation of the in vivo projection errors (equivalent to the "angular difference" between repeated exposures) produced by the new system. A filmholder, an x-ray beam manipulator, and an aiming device were newly constructed. Reference wires were attached for measuring the projection error on the filmholder and on the 22 bicuspids at the sites of investigation in 16 patients. Two exposures using standardized projection conditions were made of each site. The relative position of the reference wires on the duplicate radiographs was used to calculate the angular difference in the direction of the x-ray beam which occurred between the 2 exposures. Triplicate measurements allowed the determination of measurement error. The angular projection errors were measured in a horizontal and vertical direction. The reference wires allowed determination of the angular projection errors relative to the filmholder, relative to the dentition and the angular error due to the repositioning of the filmholder in the patient's mouth. The average projection errors deviated only slightly from zero. The largest deviation registered was -0.11 degrees. This applies to the horizontal and vertical direction and all relationships. The standard deviations varied between 0.403 degrees and 0.697 degrees. This applies to the standard deviation for all relationships in the horizontal, the vertical, and the oblique directions. The measuring error found from the triplicate measurements had a standard deviation of 0.08 degrees to 0.19 degrees depending on the distance between the reference wires. This new system for controlling in vivo projection errors seems to provide highly standardized radiographs in vivo. The new measuring system proved to be accurate enough to measure the in vivo projection errors between repeated radiographs produced with the new filmholder and x-ray beam manipulator. The in vivo errors produced by the new system are markedly smaller than all in vivo and in vitro errors previously reported in the literature.

Adult↗