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J Visser

Publications and source records attributed to J Visser.

At least 19 recordsLinked to original sources
PubMed2006

Hormonal versus non-hormonal contraceptives in women with diabetes mellitus type 1 and 2.

BACKGROUND: Adequate contraceptive advice is important in women with diabetes mellitus type 1 and 2 to reduce the risk of maternal and infant morbidity and mortality in unplanned pregnancies. A wide variety of contraceptives are available for these women. However hormonal contraceptives might influence carbohydrate and lipid metabolism and increase micro- and macrovascular complications. So caution in selecting a contraceptive method is required. OBJECTIVES: To investigate whether progestogen-only, combined estrogen/progestogen or non-hormonal contraceptives differ in terms of effectiveness in preventing pregnancy, in their side effects on carbohydrate and lipid metabolism and in long-term complications such as micro- and macrovascular disease, when used in women with diabetes mellitus. SEARCH STRATEGY: The search was performed in MEDLINE, EMBASE, CENTRAL/CCTR, POPLINE, CINAHL, WorldCat, ECO, ArticleFirst, the Science Citation Index, the British Library Inside, and reference lists of relevant articles. Last search was performed in May 2005. In addition, experts in the field and pharmaceutical companies marketing contraceptives were contacted to identify published, unpublished or ongoing studies. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials that studied women with diabetes mellitus comparing: 1. hormonal versus non-hormonal contraceptives. 2. progestogen-only versus estrogen/progestogen contraceptives. 3. contraceptives containing <50 microg estrogen versus contraceptives containing > or = 50 microg estrogen. 4. contraceptives containing 'first'-, 'second'- and 'third'-generation progestogens, drospirenone and cyproterone acetate. Principal outcomes were contraceptive effectiveness, diabetes control, lipid metabolism and micro- and macrovascular complications. DATA COLLECTION AND ANALYSIS: Two investigators evaluated the titles and abstracts from the literature search. Quality assessment was performed independently with discrepancies resolved by discussion or consulting a third reviewer. Because the trials differed in studied contraceptives, participant characteristics and methodological quality, we could not combine the data in a meta-analysis. The trials were therefore examined on an individual basis and narrative summaries were provided. MAIN RESULTS: Three randomised controlled trials were included. Only one was of good methodological quality. It compared the influence of levonorgestrel-releasing IUD versus copper-IUD on carbohydrate metabolism in women with type 1 diabetes mellitus. No difference was found in daily insulin requirement, glycosylated hemoglobin (HbA1c) or fasting blood sugar after twelve months. The other two trials were of limited methodological quality. Both compared progestogen-only pills with different estrogen/progestogen combinations. The trials reported blood glucose levels to remain stable during treatment with most regimens. Only high-dose combined oral contraceptives were found to slightly impair glucose homeostasis. Combined oral contraceptives also appeared to have a minor adverse effect on lipid metabolism whereas progestogen-only contraceptives slightly improved lipid-metabolism. Only one study reported on micro- and macrovascular complications. No signs or symptoms of thromboembolic incidents or visual disturbances were observed. However study duration was short. Minor adverse effects were reported in one study. The trial found progestogen-only pills to cause more bleeding irregularities when compared with combined oral contraceptives. Unintended pregnancies were not observed during any of the studies. AUTHORS' CONCLUSIONS: The three included randomised controlled trials in this systematic review provided insufficient evidence to assess whether progestogen-only and combined contraceptives differ from non-hormonal contraceptives in diabetes control, lipid metabolism and complications. Two of the three studies were of limited methodological quality, sponsored by pharmaceutical companies and described surrogate outcomes. Ideally, an adequately reported, high-quality randomised controlled trial analysing both intermediate outcomes (i.e. glucose and lipid metabolism) and true clinical endpoints (micro- and macrovascular disease) in users of combined, progestogen-only and non-hormonal contraceptives should be conducted. However, due to the low incidence of micro- and macrovascular disease and accordingly the large sample size and follow-up period needed to observe differences in risk, a randomised controlled trial might not be the ideal design.

Blood Glucose↗
PubMed2006

Angular spectrum of quantized light beams.

We introduce a generalized angular spectrum representation for quantized light beams. By using our formalism, we are able to derive simple expressions for the electromagnetic vector potential operator in the case of (a) time-independent paraxial fields, (b) time-dependent paraxial fields, and (c) nonparaxial fields. For the first case the well-known paraxial results are fully recovered.

Journal Article↗
PubMed2006

Comparative quantification of umbilical cord blood CD34+ and CD34+ bright cells using the ProCount-BD and ISHAGE protocols.

The total number of CD34+ cells is the most relevant clinical parameter when selecting human umbilical cord blood (HUCB) for transplantation. The objective of the present study was to compare the two most commonly used CD34+ cell quantification methods (ISHAGE protocol and ProCount - BD) and analyze the CD34+ bright cells whose 7-amino actinomycin D (7AAD) analysis suggests are apoptotic or dead cells. Twenty-six HUCB samples obtained at the Placental Blood Program of New York Blood Center were evaluated. The absolute numbers of CD34+ cells evaluated by the ISHAGE (with exclusion of 7AAD+ cells) and ProCount (with exclusion of CD34+ bright cells) were determined. Using the ISHAGE protocol we found 35.6 +/- 19.4 CD34+ cells/microL and with the ProCount method we found 36.6 +/- 23.2 CD34+ cells/microL. With the ProCount method, CD34+ bright cell counts were 9.3 +/- 8.2 cells/microL. CD34+ bright and regular cells were individually analyzed by the ISHAGE protocol. Only about 1.8% of the bright CD34+ cells are alive, whereas a small part (19.0%) is undergoing apoptosis and most of them (79.2%) are dead cells. Our study showed that the two methods produced similar results and that 7AAD is important to exclude CD34 bright cells. These results will be of value to assist in the correct counting of CD34+ cells and to choose the best HUCB unit for transplantation, i.e., the unit with the greatest number of potentially viable stem cells for the reconstitution of bone marrow. This increases the likelihood of success of the transplant and, therefore, the survival of the patient.

Antigens, CD34↗
PubMed2006

[Role of anti-Müllerian hormone in follicle recruitment and maturation].

Anti-Müllerian hormone (AMH), a member of the TGF-beta family, plays a crucial role during male sexual differentiation. This paper reviews the role of anti-Müllerian hormone in the ovary. In vivo and in vitro studies showed that AMH has an inhibitory effect on primordial follicle recruitment and it decreases the sensitivity of follicles for the FSH-dependent selection for dominance. Besides its functional role in the ovary, the AMH serum level serves as an excellent candidate marker of ovarian reserve.

Adult↗
PubMed2005

Immunophenotype of hematopoietic stem cells from placental/umbilical cord blood after culture.

Identification and enumeration of human hematopoietic stem cells remain problematic, since in vitro and in vivo stem cell assays have different outcomes. We determined if the altered expression of adhesion molecules during stem cell expansion could be a reason for the discrepancy. CD34+CD38- and CD34+CD38+ cells from umbilical cord blood were analyzed before and after culture with thrombopoietin (TPO), FLT-3 ligand (FL) and kit ligand (KL; or stem cell factor) in different combinations: TPO + FL + KL, TPO + FL and TPO, at concentrations of 50 ng/mL each. Cells were immunophenotyped by four-color fluorescence using antibodies against CD11c, CD31, CD49e, CD61, CD62L, CD117, and HLA-DR. Low-density cord blood contained 1.4 +/- 0.9% CD34+ cells, 2.6 +/- 2.1% of which were CD38-negative. CD34+ cells were isolated using immuno-magnetic beads and cultured for up to 7 days. The TPO + FL + KL combination presented the best condition for maintenance of stem cells. The total cell number increased 4.3 +/- 1.8-fold, but the number of viable CD34+ cells decreased by 46 +/- 25%. On the other hand, the fraction of CD34+CD38- cells became 52.0 +/- 29% of all CD34+ cells. The absolute number of CD34+CD38- cells was expanded on average 15 +/- 12-fold when CD34+ cells were cultured with TPO + FL + KL for 7 days. The expression of CD62L, HLA-DR and CD117 was modulated after culture, particularly with TPO + FL + KL, explaining differences between the adhesion and engraftment of primary and cultured candidate stem cells. We conclude that culture of CD34+ cells with TPO + FL + KL results in a significant increase in the number of candidate stem cells with the CD34+CD38- phenotype.

ADP-ribosyl Cyclase 1↗
PubMed2004

Neonatal oral administration of DiaPep277, combined with hydrolysed casein diet, protects against Type 1 diabetes in BB-DP rats. An experimental study.

AIMS/HYPOTHESIS: Environmental factors such as diet and bacterial antigens play an important role in the onset of Type 1 diabetes. Different self-antigens are suggested to play a role in the development of diabetes. Antibodies against the 60-kDa heat shock protein 60, which have a high homology to bacterial heat shock protein 65, have been found in the circulation at the onset of diabetes in humans and in pre-diabetic NOD-mice. One of the immunodominant epitopes in autoimmune diabetes is p277, a specific peptide of human heat shock protein 60 corresponding to positions 437-460. In this study we investigated whether neonatal oral administration of DiaPep277 (a synthetic peptide analogue of p277) affected the development of diabetes in the BioBreeding-Diabetes Prone (BB-DP) rat, and whether this could potentiate the effect of a protective hydrolysed casein-diet. METHODS: BB-DP rats were orally inoculated once per day with placebo or DiaPep277 at days 4, 5, 6 and 7 of life. At the age of 21 days rats were weaned on to a conventional, cereal-based diet or on to the hydrolysed casein-diet. RESULTS: The development of diabetes in animals receiving DiaPep277 in combination with the hydrolysed casein-diet was delayed by 17 days, and a relative reduction of the incidence by 64% was seen. Non-diabetic animals did not show any sign of insulitis. CONCLUSIONS/INTERPRETATION: Short-term neonatal feeding with p277 in early life, combined with diet adaptation, appears to provide a procedure to significantly reduce the development of Type 1 diabetes in later life.

Administration, Oral↗
PubMed2003

The spectrum of lower motor neuron syndromes.

This review discusses the most important lower motor neuron syndromes. This relatively rare group of syndromes has not been well described clinically. Two subgroups can be distinguished: patients in whom motor neurons (lower motor neuron disease (LMND)) are primarily affected or motor axons and their surrounding myelin (multifocal motor neuropathy (MMN)), both leading to muscle atrophy and weakness. Both hereditary and sporadic forms of LMND have been described. The discussion of recent advances in the genetic knowledge of several hereditary forms of LMND may lead to a better understanding of the pathophysiology and the development of therapeutic strategies. By contrast, the pathogenesis of sporadic LMND is largely unknown. It is, therefore, difficult to consider the various sporadic forms of LMND, discussed in this review, as separate diseases. Because the diagnostic and therapeutic options may differ, it would seem rational to consider sporadic LMND as a spectrum of syndromes which can be distinguished from each other on the basis of clinical presentation.MMN is a lower motor neuron syndrome with presumed immunemediated pathogenesis. Evidence of motor conduction block on nerve conduction studies and a positive response to treatment with intravenous immunoglobulins (IVIg) are considered the most relevant criteria for the diagnosis of MMN. As it is treatable, it is important to distinguish MMN from LMND. Careful electrophysiological analysis in the search for conduction block is, therefore, required in all adult patients with pure lower motor neuron syndromes. For the individual patient, distinction between the various lower motor neuron syndromes is important as it enables the physician to provide adequate information over the disease course in LMND and to facilitate early treatment in MMN.

Adolescent↗
PubMed2003

Developmental coordination disorder: a review of research on subtypes and comorbidities.

The interest in Developmental Coordination Disorder (DCD) has grown considerably over the last decade. Nevertheless, its etiology and prognosis are still poorly understood. The idea is growing that DCD may not be a uniform disorder. This review summarizes research on DCD, with a particular focus on subtype and comorbidity studies. The main message of the paper is that, in order to understand the etiology and prognosis of DCD, we need to have a better understanding of its nature. This requires an awareness of the existence of subtypes and comorbidities. Current theories on comorbidity phenomena are discussed in terms of their possible merit for the development of the field. Particular attention is given to the Automatization Deficit Hypothesis, a theory based on research on dyslexia.

Attention Deficit Disorder with Hyperactivity↗
PubMed2003

Validation of a volumic reconstruction in 4-d echocardiography and gated SPECT using a dynamic cardiac phantom.

A dynamic cardiac phantom was used as a reference to compare the volumes reconstructed with 4-D echocardiography and gated single-photon emission computed tomography (SPECT). 4-D echocardiography used a new prototype of rotating scan head to acquire ultrasound (US) images during a cardiac cycle, associated with a new protocol (left ventricular 4-D or LV 4-D) to reconstruct the volume deformations of the heart as a function of time. Gated SPECT data were acquired with a standard single-head gamma camera, and the reconstructions were carried out using the Mirage software released by Segami. The influences of different LV 4-D parameters were tested and analyzed. End-diastolic volume, end-systolic volume, and ejection fraction were measured using both LV 4-D and gated SPECT. Results obtained showed a straight correlation between the two examinations. The agreement confirmed the relevance of the comparisons. This study is an initial step before conducting clinical trials to exhaustively compare the two modalities.

Echocardiography, Four-Dimensional↗
PubMed2003

Comparison of maximal voluntary isometric contraction and hand-held dynamometry in measuring muscle strength of patients with progressive lower motor neuron syndrome.

Context. Maximal voluntary isometric contraction, a method quantitatively assessing muscle strength, has proven to be reliable, accurate and sensitive in amyotrophic lateral sclerosis. Hand-held dynamometry is less expensive and more quickly applicable than maximal voluntary isometric contraction. Objective. To investigate if hand-held dynamometry is as reliable and valid as maximal voluntary isometric contraction in measuring muscle strength in patients with an adult-onset, non-hereditary progressive lower motor neuron syndrome. Design. Two testers performed maximal voluntary isometric contraction and hand-held dynamometry measurements in six muscle groups bilaterally in patients with progressive lower motor neuron syndrome to assess reliability and validity of both the methods. Setting. Outpatient units of an academic medical center. Patients. A consecutive sample of 19 patients with non-hereditary progressive lower motor neuron syndrome (median disease duration 32.5 months, range 10-84) was tested. Outcome measures. Comparison between maximal voluntary strength contractions as measured by hand-held dynamometry and maximal voluntary isometric contraction. Results. Low intra- and interrater variation in all muscle groups were found, intraclass correlation coefficients vary between 0.86 and 0.99 for both methods. Both methods correlated well in all muscle groups with Pearson's correlation coefficients ranged between 0.78 and 0.98. Scatter plots indicated a trend to under-estimate muscle strength above 250 N by hand-held dynamometry as compared with maximal voluntary isometric contraction. Conclusions. For longitudinal evaluation of muscle strength in patients with progressive lower motor neuron syndrome (i.e. between 0 and 250 N), muscle strength can be accurate quantified with both hand-held dynamometry and maximal voluntary isometric contraction. Hand-held dynamometry has the advantage of being cheap and quickly applicable. However, our results indicate that hand-held dynamometry is less sensitive than maximal voluntary isometric contraction in detecting subnormal muscle strength in strong muscle groups (i.e. >250 N), due to limited strength of the tester.

Adult↗
PubMed2003

Sporadic lower motor neuron disease with adult onset: classification of subtypes.

The discovery of the genetic basis of hereditary lower motor neuron disease (LMND) and the recognition of multifocal motor neuropathy as a distinct clinical entity necessitate a new classification of LMND. To this end, we studied the clinical and electrophysiological features of 49 patients with sporadic adult-onset LMND in a cross-sectional study. Disease duration was more than 4 years to exclude the majority of patients with amyotrophic lateral sclerosis. Based on the pattern of weakness, we identified three groups: 13 patients with generalized weakness (group 1); eight patients with symmetrical, distal muscle weakness (group 2); and 28 patients with non-generalized asymmetrical weakness of the arms in most patients (group 3). Group 3 could be subdivided into patients with weakness in predominantly the distal (group 3a) or the proximal (group 3b) muscle groups, both with disease progression to adjacent spinal cord segments. Distinctive features of group 1 were an older age at onset, more severe weakness and muscle atrophy, lower reflexes, greater functional impairment, more widespread abnormalities on concentric needle EMG, respiratory insufficiency and serum M-protein. In groups 2 and 3, concentric needle EMG findings also suggested a more widespread disease process. Retrospectively, the prognosis of sporadic adult-onset LMND appears to be favourable, because clinical abnormalities were still confined to one limb in most patients after a median disease duration of 12 years. We propose to classify the patients in the different subgroups as slowly progressive spinal muscular atrophy (group 1), distal spinal muscular atrophy (group 2), segmental distal spinal muscular atrophy (group 3a) and segmental proximal spinal muscular atrophy (group 3b). The described clinical phenotypes may help to distinguish between different LMND forms.

Adult↗
PubMed2003

Long-term prophylactic insulin treatment can prevent spontaneous diabetes and thyroiditis development in the diabetes-prone bio-breeding rat, while short-term treatment is ineffective.

OBJECTIVE: Prophylactic insulin treatment has been demonstrated to reduce diabetes development in the diabetes-prone bio-breeding (DP-BB) rat. These prophylactic insulin treatments were given from 50 to 150 days of age. However, several data indicate that the diabetogenic process in DP-BB rats starts well before day 50. DESIGN AND METHODS: DP-BB rats were given bovine insulin pellets from 21 to 60 days of age, from 21 to 100 days of age and from 60 to 100 days of age. At 160 days of age a glucose tolerance test was performed to establish beta-cell function and pancreata collected for histological analysis. RESULTS: Prophylactic insulin treatment from 21 to 100 days of age gave a 42% reduction of diabetes incidence. The other treatment protocols had no effect. Non-diabetic rats treated with insulin from day 21 to 100 showed normal glucose tolerance and no sign of insulitis at 160 days of age. Non-diabetic rats of the control group and the other treatment groups showed normal glucose tolerance, but a slight increase of insulitis. Interestingly, the 21-100 day treated rats showed reduced serum levels of anti-colloid antibodies as compared with the control group. CONCLUSIONS: These results show that short-term prophylactic insulin treatment cannot prevent diabetes and thyroiditis development in DP-BB rats. The prophylactic treatment must start well before 60 days of age and be prolonged into the phase when the rats normally become diabetic to reduce diabetes incidence. These findings imply that in the human situation prophylactic insulin treatment must be prolonged over the normal range of diabetes onset.

Animals↗
PubMed2002

Regulation of the alpha-glucuronidase-encoding gene ( aguA) from Aspergillus niger.

The alpha-glucuronidase gene aguA from Aspergillus niger was cloned and characterised. Analysis of the promoter region of aguA revealed the presence of four putative binding sites for the major carbon catabolite repressor protein CREA and one putative binding site for the transcriptional activator XLNR. In addition, a sequence motif was detected which differed only in the last nucleotide from the XLNR consensus site. A construct in which part of the aguA coding region was deleted still resulted in production of a stable mRNA upon transformation of A. niger. The putative XLNR binding sites and two of the putative CREA binding sites were mutated individually in this construct and the effects on expression were examined in A. niger transformants. Northern analysis of the transformants revealed that the consensus XLNR site is not actually functional in the aguA promoter, whereas the sequence that diverges from the consensus at a single position is functional. This indicates that XLNR is also able to bind to the sequence GGCTAG, and the XLNR binding site consensus should therefore be changed to GGCTAR. Both CREA sites are functional, indicating that CREA has a strong influence on aguA expression. A detailed expression analysis of aguA in four genetic backgrounds revealed a second regulatory system involved in activation of aguA gene expression. This system responds to the presence of glucuronic and galacturonic acids, and is not dependent on XLNR.

Aspergillus niger↗
PubMed2002

Mimic syndromes in sporadic cases of progressive spinal muscular atrophy.

Described are patients initially diagnosed with progressive spinal muscular atrophy (PSMA), in whom further evaluation established another diagnosis. The authors prospectively investigated incident and prevalent cases of PSMA. Seventeen of 89 patients, after initial registration, were later excluded because reassessment revealed a diagnosis other than PSMA. In 11 of the 17 patients with a revised diagnosis, a potential treatment was available: multifocal motor neuropathy (7), chronic inflammatory demyelinating polyneuropathy (2), inflammatory myopathy (1), and MG (1). Other misdiagnoses included myopathy, syringomyelia, ALS, idiopathic chronic axonal polyneuropathy, and idiopathic brachial plexus neuropathy. One patient with a possible herniated lumbar disk recovered spontaneously.

Adult↗
PubMed2002

Cloning of a prolidase gene from Aspergillus nidulans and characterisation of its product.

Using EST sequence information available from the filamentous fungus Aspergillus nidulans as a starting point, we have cloned the prolidase-encoding gene, designated pepP. Introduction of multiple copies of this gene into the A. nidulansgenome leads to overexpression of an intracellular prolidase activity. Prolidase was subsequently purified and characterised from an overexpressing strain. The enzyme activity is dependent on manganese as a cofactor, is specific for dipeptides and hydrolyses only dipeptides with a C-terminal proline residue. Although these proline dipeptides are released both intracellularly and extracellularly, prolidase activity was detected only intracellularly.

Aspergillus nidulans↗
PubMed2002

Disease severity in multifocal motor neuropathy and its association with the response to immunoglobulin treatment.

Disease progression in multifocal motor neuropathy (MMN) was studied by comparing severity and duration of disease. We assessed disease severity by determining muscle weakness, disability, conduction block (CB), and distal and proximal compound muscle action potential (CMAP)-amplitude in 38 patients with MMN in whom disease duration ranged from 6 months to 34 years. As indicator for an ongoing immune-mediated process, the response to one course of IVIg treatment was measured in 34 patients and associated with disease severity. With increasing disease duration, weakness and disability became significantly more severe, and the distal and proximal CMAP-amplitude decreased significantly. The number of CBs was significantly higher in patients with a disease duration longer than 10 years than in those affected less than 10 years. Thirty of the 34 patients responded to IVIg treatment. Non-responsiveness to IVIg was not associated with any of the disease variables. Severe and widespread weakness was significantly associated with a response > or = 2 on the MRC-sum-score. Our results provide evidence for a slowly progressive disease course of MMN. The good response to IVIg treatment in patients with severe and prolonged disease indicates that progression may be the result of an ongoing immune-mediated process. These findings imply that early treatment may prevent future progression of weakness and disability in patients with MMN.

Action Potentials↗