"Wide QRS complex tachycardia in a patient with a minute ventilation (MV) rate-responsive pacemaker".
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Electrocardiography↗
Biomedical subjects
P Dekker
Publications and source records attributed to P Dekker.
Physical interaction between Wilms tumor 1 and p73 proteins modulates their functions.
The WT1 gene, which is heterozygously mutated or deleted in congenital anomaly syndromes and homozygously mutated in about 15% of all Wilms tumors, encodes tissue-specific developmental regulators. Through alternative mRNA splicing, four main WT1 protein isoforms are synthesized. All isoforms can bind to DNA via their zinc fingers, albeit with different affinities and specificities, and thereby modulate the transcriptional activity of their target genes. Several proteins bind to and alter the transcription regulatory properties of the WT1 proteins, including the product of the tumor suppressor gene p53. Interaction between WT1 and p53 was shown to modulate their ability to regulate the transcription of their respective target genes. Here, we report that all four isoforms of WT1 bind to p73, a recently cloned homologue of p53. p73 binds to the zinc finger region of WT1 and thereby inhibits DNA binding and transcription activation by WT1. Similarly, WT1 inhibits p73-induced transcription activation in reporter assays and counteracts p73-induced expression of endogenous Mdm2. This, taken together with our finding that WT1 also interacts with p63/KET, another p53 homologue, suggests that association between WT1 and the members of the p53 family of proteins may be an important determinant of their functions in cell growth and differentiation.
Alternative Splicing↗
Internal translation initiation generates novel WT1 protein isoforms with distinct biological properties.
The Wilms' tumor 1 gene, WT1, is homozygously mutated in a subset of Wilms' tumors. Heterozygous mutations in WT1 give rise to congenital anomalies. During embryogenesis, WT1 is expressed mainly in the kidneys, uterus, and testes. Alternative splicing of the WT1 mRNA results in synthesis of four main WT1 protein isoforms with molecular masses of 52-54 kDa. In addition, translation initiation at a CUG upstream of the initiator AUG generates four larger WT1 proteins of 60-62 kDa. We describe here the existence of novel WT1 isoforms and demonstrate that they are derived from translation initiation at the second in-frame AUG of the WT1 mRNA. These N-terminally truncated WT1 proteins of 36-38 kDa can be detected in several cell lines, mouse testes, and Wilms' tumor specimens. They can bind to DNA and direct transcription from reporter constructs. The shorter WT1 protein lacking the two splice inserts has a greater transcription activation potential than the corresponding main WT1 protein isoform but shows no transcription repression potential. Overexpression of full-length or N-terminally truncated WT1 efficiently induces apoptosis. These data show that additional WT1 isoforms with distinct transcription-regulatory properties exist, which further increases the complexity of WT1 expression and activity.
Alternative Splicing↗
Sutureless microvascular anastomoses by a biodegradable laser-activated solid protein solder.
A new sutureless technique to successfully anastomose the abdominal aorta of rats (1.3 mm in diameter) by using a fully biodegradable, laser-activated protein solder is presented. A total of 90 rats were divided into two groups randomly. In group one, the anastomoses were performed by using conventional microsuturing technique, whereas in group two, the anastomoses were performed by using a new laser welding technique. In addition, each of the two groups were divided into five subgroups and evaluated at different follow-up periods (10 minutes, 1 hour, 1 day, 1 week, and 6 weeks). At these intervals, the anastomoses were evaluated for patency and tensile strength. Three anastomoses in each subgroup were processed for light and electron microscopy. All anastomoses were found to be patent. The mean clamp time of the anastomoses performed with conventional suturing was 20.6 minutes compared with 7.2 minutes for the laser-activated welded anastomoses (p < 0.001). The strain measurements showed a stronger mechanical bond of the sutured anastomoses in the initial phase. However, at 6 weeks the tensile strength of the laser-welded anastomoses was higher compared with the conventional suture technique. Histologic evaluations revealed a near complete resorption of the solder after 6 weeks. The junction site of the vessel ends cannot be determined on the luminal side of the artery. In conclusion, a resorbable protein used as a solder, activated by a diode laser, can provide a reliable, safe, and rapid arterial anastomosis, which could be performed by any microsurgeon faster than conventional suturing after a short learning curve.
Anastomosis, Surgical↗
[Pressure-reducing effect of latanoprost 0.005%].
BACKGROUND: Earlier studies in monkeys have shown that latanoprost 0.005% lowers the IOP by improving the uveoscleral Outflow. We wanted to know if this is also the case in the human eye. PATIENTS AND METHODS: We used our new aqueous humor outflow test with 2-nitrophenyl-acetate in 9 healthy human volunteers, mean age 32 +/- 8.3 years. They were measured before and 12 h after receiving one drop of latanoprost 0.005% in one eye, randomly chosen. The ocular Photometer was used to quantify the disappearance of the dye out of the anterior chamber. RESULTS: The half-life time of the dye is shortened after latanoprost 0.005%. It is significantly correlated to the pressure lowering effect of latanoprost 0.005% (r2 = 0.5968). CONCLUSION: The dye-dilution technique proves that latanoprost 0.005% influences the outflow of the human eye. The better the outflow, the greater the pressure drop in the eye. The experiment nicely shows that photometric quantification of 2-nitrophenyl-acetate is a simple, reliable test for the knowledge of the aqueous humor outflow.
Adult↗
Isolation and identification of the human homolog of a new p53-binding protein, Mdmx.
We recently reported the identification of a mouse cDNA encoding a new p53-associating protein that we called Mdmx because of its structural similarity to Mdm2, a well-known p53-binding protein. Here we report the isolation of a cDNA encoding the human homolog of Mdmx. The ORF of the cDNA encodes a protein of 490 amino acids, 90% similar to mouse Mdmx. The homology between Mdmx and Mdm2 is most prominent in the p53-binding domain and the putative metal-binding domains. The Mdmx protein, which, based on SDS-PAGE, has a MW of 80 kDa, can bind p53 in vitro. The human MDMX gene is transcribed in all tissues tested, with high levels in thymus. By fluorescence in situ hybridization analysis we mapped the mouse mdmx gene to chromosome 1 (region F-G) and the human MDMX gene to chromosome 1q32.
Amino Acid Sequence↗
Primary non-Hodgkin's lymphoma of the cranial vault.
We present a case of primary B-cell, large-cell, lymphoma of the skull vault in a 50-year-old HIV-positive male, who presented with a history of unilateral headache and a swelling on the scalp. Primary non-Hodgkin's lymphoma of the skull is rare, with only ten such cases in adults previously described. We suggest that this is the second reported case in an HIV-positive individual.
Antineoplastic Combined Chemotherapy Protocols↗
MDMX: a novel p53-binding protein with some functional properties of MDM2.
Here we report the isolation of a cDNA encoding a new p53-associating protein. This new protein has been called MDMX on the basis of its structural similarity to MDM2, which is especially notable in the p53-binding domain. In addition, the putative metal binding domains in the C-terminal part of MDM2 are completely conserved in MDMX. The middle part of the MDMX and MDM2 proteins shows a low degree of conservation. We can show by co-immunoprecipitation that the MDMX protein interacts specifically with p53 in vivo. This interaction probably occurs with the N-terminal part of p53, because the activity of the transcription activation domain of p53 was inhibited by co-transfection of MDMX. Northern blotting showed that MDMX, like MDM2, is expressed in all tissues tested, and that several mRNAs for MDMX can be detected. Interestingly, the level of MDMX mRNA is unchanged after UV irradiation, in contrast to MDM2 transcription. This observation suggests that MDMX may be a differently regulated modifier of p53 activity in comparison with MDM2. Our study indicates that at least one additional member of the MDM protein family exists which can modulate p53 function.
Amino Acid Sequence↗
[Contact glass tonometer].
This paper present a tonometer incorporated in a contact lens, which allows simultaneous measurement of intraocular pressure and performance ophthalmoscopy. The tonometer can record the pulse curve continuously, which can give us an indication of any circulatory problem. The device is therefore expected to yield additional information useful for the diagnosis of early glaucoma. Te device has three force sensors built in, which allow continuous measurement of the force exerted on the eye surface by the contact lens. The force of the contact lens on the eye can be altered and makes the adjustment of different eye pressures possible. These induced changes of the eye pressure and their influence on the fundus can be checked. We have taken some measurements on enucleated human eyes to compare our device with a Statham tansducer in the vitreous. We found a good correlation. We are currently taking measurements in volunteers. The clinical relevance of these observations and measurements will be examined in a future study.
Calibration↗
[Yellow discoloration of the lens in the diabetic patient].
BACKGROUND: The yellowing is a precursor of the cataract. In the diabetic patient this phenomenon is established earlier than in normal control groups. In the literature the yellowing is explained by elevated glucose levels. Does the duration of diabetes play a key role for this phenomenon? MATERIALS AND METHODS: The yellowing of the lens can be very well detected by the ocular photometer. Using this device, 52 well regulated diabetics without retinopathy and 19 diabetics with mild background retinopathy were examined. We determined the contrast-transfer ratio of the lens, which has been correlated with the age, the duration of diabetes, the weight of the patient, the bodymass index and the hemoglobin a1c of the patient. RESULTS: Without retinopathy none of the introduced correlations were significant. If the diabetes is well regulated, even a long duration of diabetes does not cause any yellowing of the lens. With mild retinopathy the yellowing of the lens could not be detected because of the sites of measurement, which were changing. A high correlation between the duration of diabetes and the intensity of the macula and the excavation has been found. The macula gets darker and the excavation gets brighter. CONCLUSIONS: The yellowing of the lens does not depend on any of the presented parameters. In diabetics with mild background retinopathy the macula gets darker. This can be interpreted as an hyperemia of the choroid. Most probably this phenomenon is caused by the decline of sympathetic nerve fibers.
Blood Glucose↗
Oncocytic metaplasia of the nasopharynx or extra-parotid Warthin's tumour?
A case of oncocytic metaplasia obstructing the Eustachian tube in an elderly patient is described. Histologically, it was similar to Warthin's tumour of the parotid gland. The lymphocytes were predominantly T cell, unlike those of Warthin's tumour which are predominantly B cell. It is proposed that oncocytic metaplasia represents an early stage in the evolution of Warthin's tumour.
Adenolymphoma↗
A 40 kd protein binds specifically to the 5'-untranslated regions of yeast mitochondrial mRNAs.
Using a gel mobility shift assay we show that a 40 kd protein (p40), present in extracts of yeast mitochondria, binds specifically to the 5'-untranslated leader of cytochrome c oxidase subunit II mRNA. Binding of p40 to coxII RNA protects an 8-10 nucleotide segment from diethylpyocarbonate modification, indicating that the protein interacts with only a restricted region of the 5'-leader. This segment is located at position -12 with respect to the initiation AUG. Deletion of 10 nucleotides encompassing this site completely abolishes protein binding. Nevertheless, Bal31 deletion analysis within the coxII leader shows that a major part of the leader is essential for p40 binding, suggesting that binding of the protein is also dependent on secondary structural features. p40 binds to other mitochondrial leader mRNAs including those for coxI, coxIII and cyt b. p40 is present in a cytoplasmic (rho0) petite mutant lacking mitochondrial protein synthesis. It is therefore presumably nuclear encoded. The possible biological function of the protein is discussed.
Base Sequence↗
[Mutual concept formation of older and younger subjects. Stereotyping and distribution preferences].
This article analyzes the extent to which younger and older persons are apt to stereotype and discriminate age groups. Several hypotheses are tested based on a recent (1987) large scale national Dutch survey. No evidence is found for the hypothesis that positive attributes are systematically more ascribed to younger people and negative attributes systematically more to older people. Only a small minority of the Dutch population holds negative images of older people. A large majority does not discriminate between age groups or finds positive attributes more characteristic of older people. It is demonstrated, however, that older people have a more positive perception of older people - or a more negative perception of younger people - than younger people. In accordance with our hypothesis, negative stereotyping of older versus younger people is related to authoritarian attitudes and a general tendency to social discrimination. The assumption that both older and younger people favour their own age group in (hypothetical) distributions of scarce goods and tasks is in general not supported. On the contrary both age groups, especially the elderly, exhibit a surprising willingness to support the other age group.
Adolescent↗
Asymmetrical limb reduction deformities--aetiological considerations.
The clinical features of a newborn female infant with reduction deformities of three limbs and no additional major malformations are presented. Diagnostic precision is crucial for accurate prognostication since both genetic and non-genetic causes have to be considered in such instances. The main differential diagnosis in our patient included a number of specific inherited disorders of which limb reduction is a component, as well as the consequences of both early amniotic rupture and fetal vascular disruption. We favoured the latter and concluded that the risk of recurrence was minimal. The approach to limb reduction disorders should be individualized.
Abnormalities, Multiple↗
Acquired amegakaryocytic thrombocytopenic purpura: a syndrome of diverse etiologies.
The possible pathogenetic mechanisms responsible for the production of acquired amegakaryocytic thrombocytopenic purpura (AATP) were investigated in a group of patients with this disorder. Absence of megakaryocytes and small platelet glycoprotein-bearing mononuclear cells, as determined by immunochemical staining of patient marrows with an antisera to platelet glycoproteins, suggested that the defect in AATP occurs in an early progenitor cell of the megakaryocytic lineage. Using an in vitro clonal assay system for negakaryocytic progenitor cells or megakaryocyte colony-forming units (CFU-M), the proliferative capacity of AATP marrow cells was then assessed. Bone marrow cells from three of four patients formed virtually no megakaryocyte colonies, suggesting that in these individuals the AATP was due to an intrinsic defect in the CFU-M. Bone marrow cells from an additional patient, however, formed 12% of the normal numbers of colonies, providing evidence for at least partial integrity of the CFU-M compartment in this patient. Serum specimens from all six patients were screened for their capacity to alter in vitro megakaryocyte colony formation. Five of six sera enhanced colony formation in a stepwise fashion, demonstrating appropriately elevated levels of megakaryocyte colony-stimulating activity. The serum of the patient with partial integrity of the CFU-M compartment, however, stimulated colony formation only at low concentrations. At higher concentrations, this patient's serum actually inhibited the number of colonies cloned, suggesting the presence of a humoral inhibitor to CFU-M. Serum samples from all patients were further screened for such humoral inhibitors of megakaryocyte colony formation using a cytotoxicity assay. The patient whose serum was inhibitory to CFU-M at high concentrations was indeed found to have a complement-dependent serum IgG inhibitor that was cytotoxic to allogeneic and autologous marrow CFU-M but did not alter erythroid colony formation. These-studies suggest that AATP can be due to at least two mechanisms: either an intrinsic effect at the level of the CFU-M or a circulating cytotoxic autoantibody directed against the CFU-M.
Adult↗
Paroxysmal nocturnal hemoglobinuria terminating as erythroleukemia.
A case of a patient who developed erythroleukemia 3 years into the course of paroxysmal nocturnal hemoglobinuria (PNH) is presented. A case of erythroleukemia with a positive sucrose lysis test has been reported, but our case appears to be the first with a long clinical course of PNH evolving into erythroleukemia. The association between these two diseases, their possible clonal origin, and how they fit into the myelodysplastic syndromes are discussed.
Aminosalicylic Acid↗