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Biomedical subjects

R Brouwer

Publications and source records attributed to R Brouwer.

At least 19 recordsLinked to original sources
PubMed2003

Automated counting of white blood cells in synovial fluid.

OBJECTIVES: To evaluate the performance of automated leucocyte (white blood cell; WBC) counting by comparison with manual counting. METHODS: The number of WBC was determined in heparinized synovial fluid samples by the use of (i) a standard urine cytometer (Kova) and a microscope (reference method) and (ii) a haematology analyser (Sysmex XE-2100; WBC/BASO and DIFF channels). Imprecision within and between days was determined by replicate analysis of a low (level A; WBC approximately 0.560 x 10(9)/l) and a high (level B; WBC approximately 1.081 x 10(9)/l) dedicated synovial fluid control (Quantimetrix). RESULTS: The WBC count of the DIFF channel was highly correlated with the WBC count of the microscopic reference method (r = 0.99; WBC analyser = 0.870 x WBC reference method + 0.413). In contrast, no agreement existed between WBC counts generated by the WBC/BASO channel of the analyser and the reference method (r = 0.52; WBC analyser = 0.008 x WBC reference method + 0.079). Within-day imprecision (4-7%) and between-day imprecision (10%) of the haematology analyser were smaller than the within-day imprecision (12%) and the between-day imprecision (20-22%) of the manual reference method. For manual counting, inter-observer coefficients of variation were 35.9% (control level A) and 21.0% (control level B). CONCLUSIONS: The WBC count in synovial fluid can be reliably determined using the DIFF channel of the Sysmex XE-2100. Automated counting of WBC in synovial fluid offers more precise and faster results than manual counting.

Arthritis↗
PubMed2002

Clinical and serological characteristics of 125 Dutch myositis patients. Myositis specific autoantibodies aid in the differential diagnosis of the idiopathic inflammatory myopathies.

The idiopathic inflammatory myopathies (IIM) are a heterogeneous group of systemic diseases that include the familiar disease entities of dermatomyositis (DM), polymyositis (PM), and inclusion body myositis (IBM). A subset of patients has unique autoantibodies which are specific for IIM (myositis specific autoantibodies; MSAs). We studied the clinical and serological characteristics of IIM in 125 Dutch patients. Sera were analysed by immunoblotting, enzyme-linked immunosorbent assay, and immunoprecipitation. The most frequently encountered MSA was the anti-Jo-1 autoantibody (20%), followed by anti-tRNAHis (6%), anti-Mi-2 (6%), and anti-SRP (4%). The presence of certain MSAs was clearly associated with specific clinical characteristics. Anti-Jo-1 and anti-tRNAHis were associated with the anti-synthetase syndrome, anti-SRP with PM with severe myalgia and arthralgia and a moderate response to immunosuppressive treatment. A novel finding was the presence of anti-Mi-2, not only in DM, but also in PM. MSAs were frequently present in DM/PM sera, but were hardly ever detected in the sera of IBM patients. The few IBM patients with MSAs demonstrated a significant response to immunosuppressive treatment. It can be concluded that MSAs define specific clinical syndromes within the spectrum of IIM and that they can assist in the differential diagnosis and treatment plan of these enigmatic disorders by virtually excluding IBM by their presence, and by potentially identifying a subgroup of steroid-responsive IBM patients.

Adenosine Triphosphatases↗
PubMed2002

Autoantibodies against small nucleolar ribonucleoprotein complexes and their clinical associations.

Sera from patients suffering from systemic autoimmune diseases such as systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) have been shown to contain reactivities to nuclear components. Autoantibodies specifically targeting nucleolar antigens are found most frequently in patients suffering from SSc or SSc overlap syndromes. We determined the prevalence and clinical significance of autoantibodies directed to nucleolar RNA-protein complexes, the so-called small nucleolar ribonucleoprotein complexes (snoRNPs). A total of 172 patient sera with antinucleolar antibodies were analysed by immunoprecipitation. From 100 of these patients clinical information was obtained by chart review. Autoantibodies directed to snoRNPs were detected not only in patients suffering from SSc and primary Raynaud's phenomenon (RP), but also in patients suffering from SLE, rheumatoid arthritis (RA) and myositis (PM/DM). Antibodies against box C/D small snoRNPs can be subdivided in antifibrillarin positive and antifibrillarin negative reactivity. Antifibrillarin-positive patient sera were associated with a poor prognosis in comparison with antifibrillarin negative (reactivity with U3 or U8 snoRNP only) patient sera. Anti-Th/To autoantibodies were associated with SSc, primary RP and SLE and were found predominantly in patients suffering from decreased co-diffusion and oesophagus motility and xerophthalmia. For the first time autoantibodies that recognize box H/ACA snoRNPs are described, identifying this class of snoRNPs as a novel autoantigenic activity. Taken together, our data show that antinucleolar patient sera directed to small nucleolar ribonucleoprotein complexes are found frequently in other diseases than SSc and that categorization of diagnoses and clinical manifestations based on autoantibody profiles seems particularly informative in patient sera recognizing box C/D snoRNPs.

Autoantibodies↗
PubMed2001

Autoantibody profiles in the sera of European patients with myositis.

OBJECTIVE: To determine the prevalence of myositis specific autoantibodies (MSAs) and several myositis associated autoantibodies (MAAs) in a large group of patients with myositis. METHODS: A total of 417 patients with myositis from 11 European countries (198 patients with polymyositis (PM), 181 with dermatomyositis (DM), and 38 with inclusion body myositis (IBM)) were serologically analysed by immunoblot, enzyme linked immunosorbent assay (ELISA) and/or immunoprecipitation. RESULTS: Autoantibodies were found in 232 sera (56%), including 157 samples (38%) which contained MSAs. The most commonly detected MSA was anti-Jo-1 (18%). Other anti-synthetase, anti-Mi-2, and anti-SRP autoantibodies were found in 3%, 14%, and 5% of the sera, respectively. A relatively high number of anti-Mi-2 positive PM sera were found (9% of PM sera). The most commonly detected MAA was anti-Ro52 (25%). Anti-PM/Scl-100, anti-PM/Scl-75, anti-Mas, anti-Ro60, anti-La, and anti-U1 snRNP autoantibodies were present in 6%, 3%, 2%, 4%, 5%, and 6% of the sera, respectively. Remarkable associations were noticed between anti-Ro52 and anti-Jo-1 autoantibodies and, in a few sera, also between anti-Jo-1 and anti-SRP or anti-Mi-2 autoantibodies. CONCLUSIONS: The incidence of most of the tested autoantibody activities in this large group of European patients is in agreement with similar studies of Japanese and American patients. The relatively high number of PM sera with anti-Mi-2 reactivity may be explained by the use of multiple recombinant fragments spanning the complete antigen. Furthermore, our data show that some sera may contain more than one type of MSA and confirm the strong association of anti-Ro52 with anti-Jo-1 reactivity.

Antibody Specificity↗
PubMed2000

The human exosome: an autoantigenic complex of exoribonucleases in myositis and scleroderma.

The anti-PM/Scl autoantibodies are known to characterize a subset of autoimmune patients with myositis, scleroderma (Scl), and the PM/Scl overlap syndrome. The major autoantigens that are recognized by anti-PM/Scl autoantibodies are designated PM/Scl-100 and PM/Scl-75. These autoantigens have been reported to associate into a large complex consisting of 11 to 16 proteins and to play a role in ribosome synthesis. Recently, it was discovered that the PM/Scl complex is the human counterpart of the yeast (Saccharomyces cerevisiae) exosome, which is an RNA-processing complex consisting of 11 3' --> 5' exoribonucleases. To date, 10 human exosome components have been identified, although only some of these were studied in more detail. In this review, we discuss some recent advances in the characterization of the PM/Scl complex.

Autoantigens↗
PubMed2000

Three novel components of the human exosome.

The yeast exosome is a complex of 3' --> 5' exoribonucleases. Sequence analysis identified putative human homologues for exosome components, although several were found only as expressed sequence tags. Here we report the cloning of full-length cDNAs, which encode putative human homologues of the Rrp40p, Rrp41p, and Rrp46p components of the exosome. Recombinant proteins were expressed and used to raise rabbit antisera. In Western blotting experiments, these decorated HeLa cell proteins of the predicted sizes. All three human proteins were enriched in the HeLa cells nucleus and nucleolus, but were also clearly detected in the cytoplasm. Size exclusion chromatography revealed that hRrp40p, hRrp41p, and hRrp46p were present in a large complex. This cofractionated with the human homologues of other exosome components, hRrp4p and PM/Scl-100. Anti-PM/Scl-positive patient sera coimmunoprecipitated hRrp40p, hRrp41p, and hRrp46p demonstrating their physical association. The immunoprecipitated complex exhibited 3' --> 5' exoribonuclease activity in vitro. hRrp41p was expressed in yeast and shown to suppress the lethality of genetic depletion of yeast Rrp41p. We conclude that hRrp40p, hRrp41p, and hRrp46p represent novel components of the human exosome complex.

Animals↗
PubMed1999

Sitting and low back pain: the positive effect of rotary dynamic stimuli during prolonged sitting.

In this study the effect of dynamic stimuli on low back pain during prolonged sitting was investigated. The pain experience of two groups of 60 subjects with a specific low back pain was recorded. All subjects were investigated on pain behaviour by the Multidimensional Pain Inventory (MPI) and pain was measured on an open visual analogue scale (VAS). During sitting, one group received dynamic stimuli that were generated by alternating rotations in the horizontal plane of the seat of the chair, with back and arm rests in fixed position. Two different frequencies of rotation were applied in subgroups. The authors concluded that such stimuli, especially of the lower frequency, reduced pain in prolonged sitting.

Adult↗
PubMed1998

Frequent occurrence of anti-tRNA(His) autoantibodies that recognize a conformational epitope in sera of patients with myositis.

OBJECTIVE: To investigate the incidence of autoantibodies directed to deproteinized transfer RNA(His) (tRNA(His)) in anti-Jo-1 positive myositis patients and to determine the major B cell epitope. METHODS: One hundred sixty-seven myositis sera were screened by immunoblotting and enzyme-linked immunosorbent assay for the presence of anti-Jo-1 antibody. Autoantibodies directed to deproteinized RNA were detected by immunoprecipitation. Ribonuclease cleavage experiments were performed to determine the tRNA(His)-specific features important for recognition. RESULTS: Approximately one-third of the anti-Jo-1 positive sera also contained autoantibodies recognizing tRNA(His). This recognition was independent of modified bases, but the presence of stabilizing Mg2+ ions appeared to be essential for efficient immunoprecipitation. Transfer RNA(His)-specific features in the anticodon loop were not protected from ribonuclease cleavage by bound antibodies, while protection of bases located in the D and T loops was observed. CONCLUSION: A significant number of anti-Jo-1 positive myositis sera contain anti-tRNA(His) activity. Formation of the major autoepitope on tRNA(His) is strongly dependent on proper folding of this molecule mediated by an interaction between D and T loops which is stabilized by either modified residues or Mg2+ ions.

Autoantibodies↗
PubMed1995

Diagnostic analysis of total protein, albumin, white cell count and differential in ascitic fluid.

Accurate and precise procedures are described for the measurement of total protein, albumin, white cell count and differential in ascitic fluid. The total protein method (biuret) on the serum chemistry analyser, Bayer-Technicon Chem-1, was calibrated against the biuret reference method in the measuring range from 1-100 g/l, covering serum as well as ascitic fluid values. The albumin method (bromcresol green) on the Chem-1 was calibrated for the measurement range from 1-50 g/l against the new human plasma protein international reference preparations and compared to the nephelometric method on the Beckman Array, which was also calibrated against these reference preparations. A good correlation was obtained for total protein between the Chem-1 (y) and the biuret reference method (x) in 58 ascitic fluids (y = 1.02x -0.3; r = 1.00). A good correlation between the Chem-1 (y) and the Array (x) was also obtained for albumin (r = 0.99). The bromcresol green method, however, which is not fully specific, resulted in significantly higher results (y = 1.32x - 1.3). The immunochemical procedure is considered the more accurate and therefore the bromcresol green method is not suitable for the determination of albumin in ascitic fluids. The white cell count in ascitic fluid can be measured reliably by most haematology analysers if the sample is fresh and homogeneous, but the differential is flagged as a result of differing morphology. Handmade smears from ascitic fluid, however, show uneven distribution of cells and disturbed morphology.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1993

Skin contamination, airborne concentrations, and urinary metabolite excretion of propoxur during harvesting of flowers in greenhouses.

In eight greenhouses used for carnation culture, workers engaged in harvesting (n = 16), were monitored for dermal and respiratory exposure and urinary excretion of propoxur. Dermal exposure of hands and forearms was estimated from dislodgable foliar residue, using a transfer factor (a measure of transfer of pesticides from leaves to the skin) and the total number of working hours. Total estimated dermal and respiratory exposure during harvesting ranged from 0.2 to 46 mg and from 3 to 278 micrograms, respectively. To study the relationship between external and internal exposure to propoxur, respiratory and dermal exposure levels were compared with the total amount of 2-isopropoxyphenol (IPP), the major metabolite of propoxur, excreted in urine in 24 hr. The Pearson correlation coefficient between dermal exposure and the total amount of excreted IPP was 0.95. A correlation coefficient of 0.84 was found between respiratory exposure and the amount of IPP excreted. The latter association was probably caused by the covariation of respiratory and dermal exposure levels (r = 0.85). Assuming negligible oral absorption, calculations indicated that dermal exposure could account for > 80% of the amount of excreted IPP. On the basis of the amount of IPP excreted, there was no reason to suspect increased health risks for workers from exposure to propoxur during harvesting.

Agriculture↗
PubMed1992

Risk assessment of dermal exposure of greenhouse workers to pesticides after re-entry.

On 18 farms for rose culture in greenhouses in The Netherlands, dermal exposure of hands and forearms to abamectin (avermectin B1), dodemorph (4-cyclododecyl-2,6-dimethylmorpholinium acetate) and bupirimate (5-butyl-2-(ethylamino)-6-methyl-4-pyrimidinyl dimethylsulphate) was measured during crop activities. Dermal exposure during cutting (75 workers) amounted to 13 micrograms/h, 1.8 mg/h, and 2.2 mg/h for abamectin, dodemorph and bupirimate, respectively. Dermal exposure to abamectin and dodemorph during sorting (21 workers) and bundling (30 workers) was comparable with that during cutting. From the dependence of dermal exposure on the amount of dislodgeable foliar residue (DFR) a transfer factor was estimated to be 1,200, 4,550, and 2,400 cm2/h for abamectin, dodemorph and bupirimate, respectively. For sorting and bundling these factors were of the same order of magnitude. The results suggested that work rate was also a determinant of dermal exposure. The within-farm variance of dermal exposure during cutting appeared to account for approximately 30% of the unexplained part of the variation remaining after regression on DFR and application technique. The final unexplained part in the variation of dermal exposure during cutting was amongst others due to the variation between the different farms in which the measurements were performed. A health risk evaluation of the observed levels of dermal exposure after re-entry of greenhouses led to the conclusion that a health hazard may exist, especially after application of high rates of relatively toxic pesticides which easily penetrate the skin.

Agriculture↗
PubMed1992

Pesticides in the cultivation of carnations in greenhouses: Part I--Exposure and concomitant health risk.

Respiratory exposure and dermal exposure of the hands and forearms to the pesticides chlorothalonil, thiophanate-methyl, thiram, and zineb during application and during crop activities have been measured on 18 farms for carnation culture in glass-covered greenhouses in the Netherlands. Farms were selected according to a "worst case" strategy with regard to dermal exposure during cutting of flowers. For 94 workers, the geometric mean dermal exposure rate during cutting (measured on long-sleeved cotton glove monitors) was 10.1 mg/hr (active ingredient per unit of actual working time) and during sorting/bundling of these flowers by 35 workers the dermal exposure rate was 7.3 mg/hr. The average concentration in air as measured by personal air sampling during cutting after a pesticide had been dusted was 0.07 mg/m3. For the same area, spraying a pesticide exposed the applicator to a dermal exposure seven times higher than dusting. However, during dusting respiratory exposure was higher. Generally, overall exposure is higher during re-entry activities than during application. From the observed levels of dermal exposure during harvesting (re-entry) and from toxicity data, health risk occurs after application of pesticides that are relatively toxic and show relatively good skin-penetrating properties at relatively high application rates. The respiratory exposure to dusted pesticides after re-entry is about as high as during application of these pesticides and may in some situations also result in health risks. Training and education of greenhouse workers on (personal) hygiene and use of protective gloves are advocated in order to reduce exposure.

Agrochemicals↗
PubMed1992

Pesticides in the cultivation of carnations in greenhouses: Part II--Relationship between foliar residues and exposures.

The relationship between the levels of dermal and respiratory exposure to pesticides and the amount of pesticide on the leaves of the plants has been studied during cutting of carnations in greenhouses. The study was focused on four pesticides and performed in 18 farms in the Netherlands. Dermal exposure measured by using long-sleeved cotton gloves is strongly related to the amount of dislodgeable foliar residue (DFR). A transfer factor from leaves to hands of approximately 4500 cm2/hr (one-sided projected area) has been calculated. Small differences have been noticed between the different pesticides. Dermal exposure of hands and forearms to pesticides during cutting of carnations can be predicted from measurements of DFR. The DFR was mainly determined by the amount of pesticide remaining from previous applications and the last application rate, not by the application technique (spraying or dusting). The concentrations in the breathing zone after dusting of zineb (dustable powder) and chlorothalonil (wettable powder) were significantly correlated with the dislodgeable foliar residue. The concentrations of thiram did not correlate with DFR. Respiratory exposure results from dispersion of foliar dust containing pesticides.

Agrochemicals↗
PubMed1991

Relationship of airborne endotoxin and bacteria levels in pig farms with the lung function and respiratory symptoms of farmers.

Previous studies have demonstrated a high prevalence of respiratory and other symptoms and a decrement in lung function among pig farm workers, although the relationships with specific agents present in the work environment remain obscure. This study was therefore undertaken to investigate the relationship between symptoms, lung function and airborne endotoxin, ammonia and dust levels in piggeries. Information on symptoms, lung function, endotoxin, ammonia and dust levels was available for 183 pig farmers who worked in 136 farms. For 62 farms information was present on the levels of bacteria and gram-negative bacteria. For these 62 farms, endotoxin exposure measurements were taken in more than one stable. In general, no significant correlations were found between lung function and chronic respiratory symptoms, or dust and ammonia levels. The endotoxin concentration in stables was negatively related to most lung function variables, but only for the subgroup of 62 farmers was a statistically significant relationship found between endoxtoxin exposure and FEV1. A borderline statistically significant and negative relationship was found between the endotoxin concentration and the FVC. Symptoms experienced during or shortly after work showed odds ratios larger than one with the levels of bacteria, gram-negative bacteria and endotoxin, indicating a positive relationship. No consistency in the relationship between symptoms and dust levels was found. The results suggest that endotoxins and (gram-negative) bacteria probably play an important role in the development of symptoms and lung function changes among pig farmers.

Adolescent↗
PubMed1989

Effects of exposure to dust in swine confinement buildings--a working group report.

Pulmonary and other symptoms among workers in swine confinement buildings were evaluated by an international working group. In several studies in five different countries a total of about 2000 workers has been studied in clinical and epidemiologic investigations. Symptoms indicative of acute and chronic airway inflammation were widespread, as were systemic reactions of organic dust toxic syndrome. The base-line, and across workshift, pulmonary function changes were moderate. There was no evidence that antigen-antibody reactions are important in the pathogenesis. Longitudinal studies are recommended to establish the relationship between acute and chronic symptoms and end stage disease.

Agricultural Workers' Diseases↗
PubMed1988

myc and sis expression in acute myelogenous leukemia.

Several oncogenes have been reported to be expressed in normal and malignant hematopoietic cells. Since these studies have almost exclusively been done by Northern and dot blot hybridization techniques using mixed populations of cells, any conclusions concerning quantitative changes in gene expression are difficult to document. We have developed a rapid and sensitive RNA-in situ hybridization technique permitting detection of as few as five copies of mRNA per cell. Using this technique we have studied the expression of two genes, c-myc and c-sis, in acute leukemia patients as well as hematologically normal individuals. We have found that expression levels of myc and often sis are higher (greater than 5-fold) in hematopoietic cells obtained from leukemia patients than in normal hematopoietic cells. In regenerating marrow, there is a dramatic increase in the frequency of cells expressing myc at the level of five to 10 copies without the presence of any cells expressing myc at the high levels found in acute leukemia. This is completely different from leukemic remission marrow in which we find a subpopulation of cells which express myc at very high levels. At this time, the leukemic origin of this abnormal cell population is likely because of the close correlation we find between gene overexpression and leukemic phenotype as identified by double-labeling experiments. It appears that gene overexpression may be a more sensitive or an earlier marker for leukemic cells and that such an assay could be used in the detection of residual disease.

Bone Marrow↗