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H Engels

Publications and source records attributed to H Engels.

At least 37 records · Page 2Linked to original sources
PubMed1997

Molecular investigation of the parental origin of a de novo unbalanced translocation 13/18.

We report a patient with a de novo translocation 13/18, identified by high-resolution banding. The breakpoints were ascertained by fluorescence in situ hybridisation with whole chromosome 13 and 18 paints. Short tandem repeat typing demonstrated the aberration to be of combined maternal/paternal origin and thereby confirmed its de novo and postzygotic formation. Thus, a gonadal mosaic in one of the parents resulting in a higher recurrence risk could be excluded.

Abnormalities, Multiple↗
PubMed1996

Tetrasomy 18p de novo: identification by FISH with conventional and microdissection probes and analysis of parental origin and formation by short sequence repeat typing.

We report a de novo supernumerary isochromosome 18p in a child with tetrasomy 18p, analyzed by a straightforward combination of cytogenetic and molecular cytogenetic methods. The diagnostic procedure consisted of standard banding techniques and fluorescence in situ hybridization (FISH) with centromere and library DNA probes for chromosome 18, and 18p-specific FISH probes prepared by chromosome dissesction and in vitro amplification. The maternal origin as well as the most probable cell stages of formation of the supernumerary isochromosome were determined by typing of short sequence repeats (SSRs). The pattern of allelic distribution suggests a nondisjunction during meiosis followed by a centromeric misdivision in an early postzygotic mitosis as the most probable mode of isochromosome 18p formation. The combination of the applied methods represents a powerful tool to investigate the nature and the origin of de novo marker chromosomes.

Alleles↗
PubMed1992

Cervical cancer screening and detection of genital HPV-infection and chlamydial infection by PCR in different groups of Kenyan women.

A pilot study was conducted in Nairobi, Kenya, to evaluate the feasibility of a larger study on the prevalence of cervical cancer and precancerous lesions and on the role of Sexually Transmitted Diseases (STD) as risk factors for cervical cancer in Kenya. 692 women were screened for cervical cancer by cytology in 3 City Commission family planning clinics and in 1 City Commission STD referral clinic in Nairobi. In one family planning clinic and in the STD clinic, a sample of the participating women (n = 212) was also screened for genital Human Papillomavirus (HPV) and chlamydial infection by Polymerase Chain Reaction (PCR). Of all women screened for cancer, 5.1% had a PAP smear showing mild dysplasia, 1.2% moderate dysplasia and 0.15% severe dysplasia or worse. Of the women screened for genital HPV infection and for chlamydial infection, the following results can be reported: in women attending the family planning clinic, HPV-DNA was detected in 3.7% (0.9% HPV6/11 and 2.8% HPV 16/18/31/33) and Chlamydia trachomatis in 6.4%; in women attending the STD clinic, HPV-DNA was detected in 16.5% (1% HPV6/11 and 2.8% HPV 16/18/31/33) and Chlamydia trachomatis in 4%. A significantly higher frequency of HPV-infection was observed in the STD clinic, while this was not the case for chlamydial infection.

Adolescent↗
PubMed1990

Incidental magnetization transfer contrast in standard multislice imaging.

Radio frequency magnetic fields from 5 to 100 kHz off resonance reduce longitudinal magnetization of water in some tissues without affecting the magnetization of simple solutions (Wolff, S.D.; Balaban, R.S. Magnetization transfer contrast (MTC) and tissue water proton relaxation in vivo. Magn. Reson. Med. 10:135-144; 1989). We demonstrate that off resonant fields used in day to day multislice imaging have a significant effect. Extra slices reduced brain (gray and white matter) and muscle intensities 10%-20% relative to fat, water, and paramagnetic solutions, a larger effect than produced by slice overlap. Implications for image contrast and quantitation are discussed.

Body Water↗
PubMed1990

Evaluation of magnetic resonance velocimetry for steady flow.

Whole body magnetic resonance (MR) imaging has recently become an important diagnostic tool for cardiovascular diseases. The technique of magnetic resonance phase velocity encoding allows the quantitative measurement of velocity for an arbitrary component direction. A study was initiated to determine the ability and accuracy of MR velocimetry to measure a wide range of flow conditions including flow separation, three-dimensional secondary flow, high velocity gradients, and turbulence. A steady flow system pumped water doped with manganese chloride through a variety of test sections. Images were produced using gradient echo sequences on test sections including a straight tube, a curved tube, a smoothly converging-diverging nozzle, and an orifice. Magnetic resonance measurements of laminar and turbulent flows were depicted as cross-sectional velocity profiles. MR velocity measurements revealed such flow behavior as spatially varying velocity, recirculation and secondary flows over a wide range of conditions. Comparisons made with published experimental laser Doppler anemometry measurements and theoretical calculations for similar flow conditions revealed excellent accuracy and precision levels. The successful measurement of velocity profiles for a variety of flow conditions and geometries indicate that magnetic resonance imaging is an accurate, non-contacting velocimeter.

Aorta, Thoracic↗
PubMed1989

[Genital human papillomavirus infections in certain groups of women in the Antwerp region].

Different groups of women, living in the Antwerp region, are examined for the occurrence of genital human papillomavirus (HPV)-infections. To detect these infections, physical examination and DNA-DNA-hybridisation technics (Southern Blotting with the probes of HPV 6, 11, 16 and 18) have been used. Part of these women are also examined colposcopically. The following groups of women have been included in the study: --women who present for cervical cancer screening with their general practitioner after a communal campaign. (HPV detection by physical examination, cytology and hybridisation); --women who present for cervical cancer screening with the mobile team after a communal campaign. (HPV detection by physical and colposcopical examination, by cytology and by hybridisation); --women who are routinely screened for cervical cancer in a gynecological private practice, situated in the same region. (HPV detection by physical examination and hybridisation). Prevalences of HPV infections in these groups will be presented and the detection methods used will be discussed.

Adult↗
PubMed1989

[The use of the cervix brush for early diagnosis of cervix uteri cancer: quality of the smear].

From may 1988 till may 1989, a cervix-brush has been used to take smears by a group of general practitioners involved in a cervical cancer screening program. These smears are compared--retrospectively--with a selection of smears from previous cervical cancer screening programs. The collection devices previously used were an Ayre spatula and an Ayre spatula combined with a cotton tipped swab. All smears have been cytologically examined by the Center for Cancer Prevention of the UIA and have been described using the standardized KOPA-method. 3 Groups of smears have been included in the study: --group 1 (n = 299): use of a cervix-brush --group 2 (n = 1315): use of an Ayre spatula --group 3 (n = 1450): use of an Ayre spatula + cotton tipped swab. Concerning their previous experience in taking smears, all the participating GP's are considered to be comparable. There was a slight difference in the age distribution of the women examined, between group 1 and the other 2 groups. From this study, we concluded: --a larger number of smears from the group using the cervix-brush (group 1) has been described as having "good quality". This result was confirmed after matching for age group. --the number of abnormal smears detected was comparable for all groups.

Female↗
PubMed1979

[The postnatal growth of the skull in the house mouse Mus musculus Linné, 1758, and in 2 different large subspecies of the field mouse Microtus arvalis Pallas, 1779. I. Introduction, materials and methods].

In order to describe postnatal skull growth in Mus musculus, Microtus arvalis arvalis and M. a. asturianus, a total of 408 animals were raised and measured. The growth rate of single bones was followed by means of a maximum-likelihood estimator for the parameters A, B and C of the growth function Y(t) = A-B exp(-Ct). Supplementary techniques used to estimate the morphological divergence of the different taxa included methods of allometry research and multivariate statistical methods such as discriminate analysis and MANOVA. Drawings of selected stages of skull-bone ossification are provided to assist researchers in determining the age of undated specimens.

Animals↗
PubMed1979

[Post-natal growth of the skull in the house mouse Mus musculus Linné, 1758, and in 2 different large subspecies of the field mouse Microtus arvalis Pallas, 1779. II. Results (I)].

Postnatal skull ontogeny of Mus musculus, Microtus arvalis arvalis and M. a. asturianus was studied qualitatively and quantitatively. To facilitate age determination for undated specimens, the most important stages in ossification of the skull bones are described, with drawings of selected ontogenetic stages (Part I). Using Parameter C of the growth function Y(t) = A - B exp (- Ct), it is possible to establish skull growth gradients. The growth functions are subdivided into 3 classes, based on Parameter C, associated with different growth regions of the skull. Changes in individual skull proportions are demonstrated by means of ontogenetic and intraspecific allometries.

Animals↗
PubMed1978

Preparation and properties of acetylcholinesterase from the sea mussel Mytilus edulis.

The large-scale isolation of an acetylcholinesterase from the haemolymph of the sea mussel mytilus edulis by means of fractional (NH4)2SO4 precipitation, affinity chromatography and isoelectric focusing is described. The yield is about 20% of the initial enzyme activity with a specific activity of 1727 nkat/mg protein. Purification steps are followed by disc electrophoresis, analytical isoelectric focusing and immunoelectrophoresis, showing the enzyme to be homogeneous with an isoelectric point of 4.81 +/- 0.02 and to have an apparent molecular weight of 245,000, which is composed by six equal subunits as judged by C- and N-terminal amino acid analysis. The acetylcholinesterase is a metalloprotein containing three Fe2 ions per subunit (molecular weight 40625); this consists of 351 amino acid and six sugar residues, but contains no sialic acid. As calculated from CD data, the enzyme has about 55% helical structure.

Acetylcholinesterase↗
PubMedDate not supplied

"Keyhole" method for accelerating imaging of contrast agent uptake.

Magnetic resonance (MR) imaging methods with good spatial and contrast resolution are often too slow to follow the uptake of contrast agents with the desired temporal resolution. Imaging can be accelerated by skipping the acquisition of data normally taken with strong phase-encoding gradients, restricting acquisition to weak-gradient data only. If the usual procedure of substituting zeroes for the missing data is followed, blurring results. Substituting instead reference data taken before or well after contrast agent injection reduces this problem. Volunteer and patient images obtained by using such reference data show that imaging can be usefully accelerated severalfold. Cortical and medullary regions of interest and whole kidney regions were studied, and both gradient- and spin-echo images are shown. The method is believed to be compatible with other acceleration methods such as half-Fourier reconstruction and reading of more than one line of k space per excitation.

Contrast Media↗
PubMedDate not supplied

Accessory equipment considerations with respect to MRI compatibility.

The MR Section of The National Electrical Manufacturers Association (NEMA), in response to a request from the Food & Drug Administration (FDA), recently issued a position paper to address generic issues related to the compatibility of accessory equipment produced by third party equipment manufacturers or MR equipment users and intended to be used in conjunction with MR equipment or within the MR scanning room. The recommendations concern scanning accessories, such as radiofrequency (RF) coils, patient monitoring equipment and injectors, as well as patient comfort accessories and positioning devices. The following issues related to safety performance are discussed: (a) the interaction of the equipment with the MR scanner, (b) interactions of the MR scanner with the equipment, and (c) potential safety hazards for patients and staff that can be posed by accessory equipment in the MR scan environment. The recommendations are based on combined input from NEMA member companies who manufacture MR systems and MR accessories and are presented for consideration in the design of MR accessory products and incorporation of these concepts into testing plans to ensure MR compatibility of third party devices.

Equipment Design↗
PubMedDate not supplied

Unbalanced translocation 8;Y (45,X,dic(Y;8)(q11.23;p23.1)): case report and review of terminal 8p deletions.

A boy with a rare unbalanced de novo Y/autosome translocation is presented. Main clinical features in the boy comprised a psychomotor delay, talipes planus, a dolichocephalus, low set and retroverted ears, supraorbital fullness of subcutaneous tissue and a bulbous nasal tip. Chromosomal analysis on amniocytes showed a single X chromosome and a derivative 8p (Karyotype: 45,X,der(8)GTG). The following DAPI staining revealed the inactivated centromere of the chromosome Y located on 8p and the absence of heterochromatic material Yq. Microsatellite analysis on fetal blood DNA using markers between SRY on Yp and DYS 240 on Yq proved presence of the spermatogenetic relevant factors. A terminal deletion of 8p was confirmed by FISH postnatally. Molecular genetic reassessment revealed the monosomy 8p to be of maternal origin; the translocation can thus be proven to have occurred in the zygote. The breakpoint in 8p was localised distal to GATA4, a gene which is involved in heart development; the finding that our patient did not suffer from cardiac problems agrees with the disomic presence of GATA4. Only the application of FISH combined with microsatellite analysis allowed a precise correlation between clinical phenotype and a subtle deletion of terminal 8p; furthermore, a recurrence risk for the parents could be excluded.

Child↗