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Biomedical subjects

M de Haan

Publications and source records attributed to M de Haan.

54 records · Page 3Linked to original sources
PubMed1997

Recognition of the mother's face by six-month-old infants: a neurobehavioral study.

Event-related potentials (ERPs) were recorded from 6-month-olds as each watched pictures of the mother's face and a stranger's face. The ERPs differed for the 2 faces, but the pattern of neural activity elicited depended on whether the mother and stranger looked different (Experiment 1, n = 22) or alike (Experiment 3, n = 22). In contrast, when different 6-month-olds were each shown 1 of these 44 pairs of faces their ERPs did not differ between the 2 faces (Experiment 2, n = 22, and Experiment 4, n = 22). In a visual preference test of recognition, infants showed no evidence of recognizing the mother's face (Experiment 5, n = 32). Together, these results suggest that infants are able to recognize their mothers' faces but (1) the neural processes accompanying recognition depend on the difficulty with which mother can be discriminated from stranger and (2) under the conditions investigated in this study, ERPs are a more sensitive measure of recognition than is looking time.

Arousal↗
PubMed1996

[Cause for referral by family physicians and obstetricians in Amsterdam in (threatened) miscarriage as reflected in the guideline '(Threatened) abortion' of the Dutch Society for Family Physicians].

OBJECTIVE: To determine the reasons general practitioners (GPs) and midwives have for referring patients with symptoms of imminent miscarriage to hospital and the management in hospital. DESIGN: Prospective and descriptive. SETTING: Research Centre Primary/Secondary Health Care, University Hospital Free University, the "Onze Lieve Vrouwe Gasthuis' hospital, both in Amsterdam, the Netherlands. METHOD: During the period August 1994-February 1995 anamnesis, diagnostics, diagnosis and further management were recorded for all patients who visited the "Onze Lieve Vrouwe Gasthuis' hospital with blood loss and/or pain in the first 16 weeks of gestation. Patients revealed their wishes concerning referral by filling in questionnaires. Their GPs/midwives were asked about the referral motives in a telephone interview. RESULTS: In the hospital 105 patients were recorded; 34% came on their own initiative. In hospital none of the patients with the diagnosis "imminent miscarriage' was referred back to the GP/midwife. Only 59% of the GPs/midwives performed the physical examinations the (imminent) miscarriage guideline of the Dutch College of General Practitioners advises. In 56% of the 32 patients referred there was no reason for referral according to the (imminent) miscarriage guideline. CONCLUSION: The (imminent) miscarriage guideline issued by the Dutch College of General Practitioners was not always followed because patients went to the hospital on their own account, GPs/midwives did not agree with the guideline, patients wanted another policy and obstetricians kept patients in their own care.

Abortion, Threatened↗
PubMed1995

[Does the '(Imminent) miscarriage standard of the Dutch College of Family Physicians correspond to the management by gynecologists?].

OBJECTIVE: To determine if the '(Imminent) miscarriage' standard issued by the Dutch College of General Practitioners corresponds to the management by obstetricians. DESIGN: Postal questionnaire. SETTING: Research Centre Primary/Secondary Health Care, Free University Hospital Amsterdam. METHOD: A postal questionnaire was sent in 1994 to all partnerships of obstetricians (n = 122) in the Netherlands about their management in case of an imminent miscarriage. RESULTS: The response rate was 86% (n = 105). Nearly all partnerships (94%) had an agreement about their management in case of an imminent miscarriage, but the individual protocols varied. In case of a miscarriage or an imminent miscarriage 10% and 28% respectively of all partnerships said they would refer the woman to the GP or midwife. Furthermore, 21% of all partnerships said that the GP or midwife could not have an ultrasound scan made themselves, i.e. without referring to the obstetrician. Many respondent knowing the GP standard (64%) did not agree with the guidelines restricting ultrasound scans (39%) or advising expectative management (24%). They thought that an ultrasound scan was essential to diagnosis and that an expectative management would increase the risk of severe blood loss. On the other hand 15% agreed to all the guidelines. CONCLUSION: The management of obstetricians with respect to (imminent) miscarriage is diverse and does not correspond to the guidelines of the '(Imminent) miscarriage' GP standard, notably with respect to the advised expectative management.

Abortion, Threatened↗
PubMed1994

Complete DNA sequence of yeast chromosome II.

In the framework of the EU genome-sequencing programmes, the complete DNA sequence of the yeast Saccharomyces cerevisiae chromosome II (807 188 bp) has been determined. At present, this is the largest eukaryotic chromosome entirely sequenced. A total of 410 open reading frames (ORFs) were identified, covering 72% of the sequence. Similarity searches revealed that 124 ORFs (30%) correspond to genes of known function, 51 ORFs (12.5%) appear to be homologues of genes whose functions are known, 52 others (12.5%) have homologues the functions of which are not well defined and another 33 of the novel putative genes (8%) exhibit a degree of similarity which is insufficient to confidently assign function. Of the genes on chromosome II, 37-45% are thus of unpredicted function. Among the novel putative genes, we found several that are related to genes that perform differentiated functions in multicellular organisms of are involved in malignancy. In addition to a compact arrangement of potential protein coding sequences, the analysis of this chromosome confirmed general chromosome patterns but also revealed particular novel features of chromosomal organization. Alternating regional variations in average base composition correlate with variations in local gene density along chromosome II, as observed in chromosomes XI and III. We propose that functional ARS elements are preferably located in the AT-rich regions that have a spacing of approximately 110 kb. Similarly, the 13 tRNA genes and the three Ty elements of chromosome II are found in AT-rich regions. In chromosome II, the distribution of coding sequences between the two strands is biased, with a ratio of 1.3:1. An interesting aspect regarding the evolution of the eukaryotic genome is the finding that chromosome II has a high degree of internal genetic redundancy, amounting to 16% of the coding capacity.

Base Composition↗
PubMed1994

Follow-up of pregnancies, infants, and families after multifetal pregnancy reduction.

OBJECTIVE: To evaluate the course of multifetal pregnancies and also the long-term pediatric and psychosocial follow-up of surviving offspring and their parents after selective reduction. DESIGN: Follow-up study. SETTING: University hospital and subject's homes. PATIENTS: Twenty-one couples with high-order multiple pregnancies resulting from infertility treatment were referred from all over the Netherlands. A total of 36 infants (15 twins and 2 triplets) were included in the follow-up. INTERVENTION: Pregnancy reduction by transabdominal approach at a median of 11 (9 to 13) weeks gestation. One assessment took place between the age of 9 months and 6 years after delivery. MAIN OUTCOME MEASURES: Pregnancy outcome, health of the infants, and psychosocial impact upon their parents after infertility treatment and the multifetal pregnancy reduction. RESULTS: Abortion within 4 weeks after pregnancy reduction did not occur in this series. Six infants (13.7%) died perinatally. Two infants (4.4%) died at the ages of 12 days and 3 months, respectively. Early preterm delivery was the cause of death in all cases. The development of the infants was appropriate to gestational age and birth weight. At follow-up, 14 couples disclosed at the time they were unaware of the risks and the consequences of infertility treatment. Nine couples indicated they had feelings of guilt after pregnancy reduction. These feelings, however, were not disclosed at the time of the interviews, during which none of the families showed either regret or distress about their decision. Two couples only occasionally experienced some grief and mourning reactions for the reduced fetuses. CONCLUSIONS: Pregnancy reduction is an acceptable option in the case of excessive multifetal conceptions after infertility treatment regimes. There are no adverse effects on either the infants and their families provided that the procedure is carefully planned and performed and the couples are given full support both before and after the procedure.

Female↗
PubMed1994

Care for the imminent miscarriage by midwives and GPs.

A postal questionnaire was sent to a random sample of 495 Dutch general practitioners (GPs) and 278 midwives to evaluate the use of the 'imminent miscarriage' standard used by the Dutch College of General Practitioners. The response rates were 63 and 87% respectively. The first questions asked related to the respondents' routine management of an imminent miscarriage. The second part of the questionnaire addressed the respondents' attitude to the 17 most important guidelines in the standard. Finally, the respondents were invited to describe problems arising in adhering to the standard. Midwives and GPs differed in their management of an imminent miscarriage. Midwives used more 'technology' such as ultrasound scans or a doptone to trace complications or see if the fetus was still viable, whereas the GPs more often carried out vaginal and speculum examinations. Midwives also paid more attention to care following a miscarriage. The guidelines that many respondents did not adhere to involved the period of 10 days for the follow-up appointment and counselling after 6 weeks. Guidelines restricting ultrasound scans and the decision only to refer the patients to an obstetrician after three consecutive miscarriages were also not accepted by all respondents. Respondents mentioned several practical problems or obstacles in adhering to the standard, including women's requests for ultrasound scans or referrals and also the attitude of obstetricians who sometimes simply assumed control. The results will serve as a starting point for updating the standard.

Abortion, Spontaneous↗
PubMed1992

[Paced addition. A neuropsychological test for assessment of divided attention].

The Pasat (Paced auditory serial addition task) is a test requiring addition of simple digits presented auditorily in several series of a successively higher pace of presentation. The task reflects the capacity for divided attention, is a measure of information processing speed and has appeared to be sensitive to minor attention deficits. We made a Dutch version characterized by longer time intervals between digits, for use in a study among (altogether 130) middle-aged and elderly persons. This modified version was evaluated with respect to feasibility. It appeared to be fairly feasible, provided sufficient opportunity for practice is given. Two series with inter-stimulus intervals of 4 and 3 seconds respectively were then evaluated with respect to validity and reliability in subjects of 48 to 74 years. Both Pasat series correlated well with two tests of attention: Digit Symbol (WAIS) and d2-test (r = 0.53-0.67), the relation with reaction decision speed being generally weak (r = 0.29-0.33) and weak to absent with a number of memory tests (r = -0.04-0.29). The Pasat performance shows a positive relationship with educational level and intelligence (inter-stimulus interval 4 seconds: r = 0.28 and 0.33 resp.; inter-stimulus interval 3 seconds: r = 0.40, 0.57 resp.). The stability of test performance over a period of about two months is moderate (r = 0.54, 0.61 resp.). In view of the excellent inter-observer reliability (r = 0.99) and the good parallel-test reliability (r = 0.79, 0.68 resp.), this might be explained by fluctuations in the capacity measured, rather than measurement error.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Dendritic cells and class II MHC expression on thyrocytes during the autoimmune thyroid disease of the BB rat.

The BB rat is a well-established model for spontaneous thyroid autoimmune disease. Since antigen presentation in thyroid autoimmunity is still a matter of debate, we studied the presence of antigen-presenting dendritic cells in the thyroid of the BB/O rat during the development of the disease in relation to the presence of other leucocytes and the aberrant expression of class II MHC determinants by thyrocytes. Thyroid glands, as well as thyroid-draining lymph nodes, were investigated in enzyme histochemistry and immune histochemistry. The appearance of anti-colloid antibodies in the circulation at 6 weeks of age was accompanied by an increase in the weight of the thyroid-draining cervical lymph nodes, which contained many anti-thyroglobulin-producing plasma cells. The only noteworthy event in the thyroid gland in this early stage of the disease was an increase in the number of dendritic cells. T cells, B cells, and plasma cells were virtually absent from the thyroid, and thyrocytes were invariably negative for class II MHC determinants. Only after 18 weeks of age, when large accumulations of dendritic cells, B lymphocytes, and T lymphocytes were seen in 40% of the BB thyroids, could some class II MHC positive thyroicytes be observed. At this stage the thyroid also contained some anti-thyoglobulin-producing plasma cells. Our observations suggest that dendritic cells play a role in antigen presentation in the early stages of the thyroid autoimmune response.

Animals↗
PubMed1988

Demarcation of a sequence involved in mediating catabolite repression of the gene for the 11 kDa subunit VIII of ubiquinol-cytochrome c oxidoreductase in Saccharomyces cerevisiae.

A regulatory element has been identified in the promoter region of the gene encoding the 11 kDa subunit VIII of the ubiquinol-cytochrome c oxidoreductase in Saccharomyces cerevisiae. The element, which is approximately 40 bp long and situated 185 bp upstream of the initiator ATG, is essential for induction of gene expression during growth in the presence of non-fermentable carbon sources. This is shown by the regulated synthesis of beta-galactosidase in yeast cells harbouring a CYC1-lacZ fusion gene, in which the CYC1 UAS's had been replaced by a 43 bp subunit VIII gene promoter fragment. In addition two DNA-binding activities, which may represent either separate factors or different forms of a single factor, have been detected. Both factors are abundant and they bind in a mutually exclusive fashion to a DNA sequence just upstream of the regulatory element. Although it is unlikely that these factors are directly involved in the response of the subunit VIII gene to catabolite repression, the position of their binding sites relative to the UAS and to the 3'-terminus of a gene located only 361 bp upstream suggest that they are important in modulating transcriptional activity of this region.

DNA, Fungal↗
PubMed1988

Noonan syndrome: partial factor XI deficiency.

Among the multiple extracardiac abnormalities seen in the Noonan syndrome, several authors have mentioned an unexplained bleeding tendency. In 1983 Kitchens and Alexander reported on a partial deficiency of coagulation factor XI in four patients with Noonan syndrome. We examined 9 patients with Noonan syndrome and 9 of their 18 parents (3 of them also had Noonan syndrome). Four Noonan patients were found to have a partial deficiency of factor XI (30-65%). The Noonan patients had a mean factor XI level of 67%, significantly lower than the normal parents (mean level of 109%). Our study suggests a relationship between Noonan syndrome and a partial deficiency of factor XI.

Blood Coagulation Disorders↗
PubMed1988

RNA splicing in yeast mitochondria: DNA sequence analysis of mit- mutants deficient in the excision of introns aI1 and aI2 of the gene for subunit I of cytochrome c oxidase.

We have characterized two yeast mutants deficient in the splicing of transcripts of the mitochondrial gene for cytochrome c oxidase subunit I (coxI). Both map to the first intron (aI1). RNA blot analysis shows that in addition to a reduced (mutant M15-190) or blocked (mutant M12-193) excision of the mutated intron aI1, the mutants are unable to excise the adjacent aI2 intron, the reading frame of which displays an amino acid sequence similarity to aI1. Splicing of the downstream introns is not affected, however. Sequence analysis of the first mutant DNA (M12-193) reveals a premature termination of the intron-encoded open reading frame, followed by two alterations at a short distance downstream. The other (M15-190) contains 11 separate changes. Although these occur in the intron reading frame, their main effect on RNA splicing may be exerted through the disturbance of intron secondary structure proposed for the 5' end of several group II introns. The implications of these findings in relation to maturase function and structure of intron aI1 are discussed.

Base Sequence↗
PubMed1987

Dendritic cells in autoimmune thyroid disease.

Dendritic cells form a morphologically distinct class of cells characterized by shape, reniform nucleus, absent to weak acid-phosphatase activity and strong Class II MHC determinant positivity. Functionally they are the most efficient cells in antigen presentation to T-lymphocytes which indicates their role in the initiation of an immune response. Using immunehistochemical techniques we studied the presence of dendritic cells in normal Wistar rat and human thyroids, in thyroids of BBW rats developing thyroid autoimmunity and in Graves' goitres. Dendritic cells could be identified in all thyroids studied and were positioned underneath the thyrocytes in between the follicles. Skin dendritic cells travel via lymphatics to draining lymph nodes, thus forming an antigen presenting cell system. It is likely that a similar cell system exists on the level of the thyroid for dendritic cells have also been detected in thyroid draining lymph nodes. In normal thyroid tissue of both human and rat dendritic cells were relatively scarce. During the initial phases of the thyroid autoimmune response in the BBW rat (before the appearance of Tg-antibodies in the circulation) numbers of thyroid dendritic cells increased. Intrathyroidal T-helper cells, B-cells or plasma cells could not be found. The thyroid draining lymph node contained large numbers of plasma cells. During the later stages of the thyroid autoimmune response in the BB/W rat (after the appearance of Tg-antibodies in the circulation) and in Graves' goitres dendritic cells were not only present in high number, but 20-30% were seen in contact with now-present intrathyroidal T-helper lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1985

[The effect of lowering the hematocrit on polycythemia and thrombocytopenia in congenital cyanotic heart defect].

The clinical history of a 15 year old girl with Down's syndrome and a complete atrioventricular septal defect undergoing blood-letting and plasma administration as a palliative treatment of polycythaemia and thrombocytopenia. A clear clinical improvement and a rapid increase of the thrombocyte count has been observed. The palliative treatment has to be continued with intervals after the therapeutic trial.

Adolescent↗
PubMed1983

Two intron sequences in yeast mitochondrial COX1 gene: homology among URF-containing introns and strain-dependent variation in flanking exons.

The DNA sequences of two optional introns in the gene for subunit I of cytochome c oxidase in yeast mitochondrial DNA have been determined. Both contain long unassigned reading frames (URFs). These display regions of amino acid homology with six other URFs, two of which encode proteins involved in mitochondrial RNA splicing. Such conserved regions may thus define functionally important domains of proteins involved in RNA processing. This homology also implies that these URFs had a common ancestral sequence, which has been duplicated and dispersed around the genome. Comparison of the flanking exons in the long strain KL14-4A with their unsplit counterpart in D273-10B reveals clustered sequence differences, which lead in D273-10B to codons rarely used in exons. These differences may be linked to the loss or absence of one of the optional introns.

Base Sequence↗
PubMedDate not supplied

Simultaneous enumeration of T-cell subsets and macrophages in bronchoalveolar lavage fluids by immunoenzyme double staining. Comparison with conventional immunofluorescence.

Bronchoalveolar lavage is a common research and clinical tool for the retrieval of cells from the lower respiratory tract. In addition to conventional morphologic study of these cells, the subtyping of T lymphocytes is often important for reaching a diagnosis of a disease or assessing its activity; subtyping is usually done by a standard immunofluorescence assay on cell suspensions requiring about 5 X 10(5) cells. Since the number of leukocytes in the lavage fluid from many patients is too small to obtain reliable information by this assay, a double immunoenzyme staining of T-lymphocyte subtypes on Cytospin preparations was utilized. This method, which requires a small number of cells, was compared with the standard immunofluorescence assay for the identification and quantitation of lymphocyte subtypes in the lavage fluids of patients with different disorders. Although the immunoenzyme double staining assay is somewhat more laborious, it provides important advantages: (1) simultaneous observation of two lymphocyte subsets and macrophages on the same slide; (2) a considerably smaller number of cells (2 X 10(4) instead of 5 X 10(5] is necessary; (3) the availability of permanent preparations; (4) the possibility of storing the Cytospin slides before staining; and (5) conventional light microscopy can be used. Since the reliability of both techniques appeared to be the same, the double staining assay for routine usage with bronchoalveolar lavage fluids appears to be preferable.

Bronchoalveolar Lavage Fluid↗