Biomedical subjects

M Gerke

Publications and source records attributed to M Gerke.

10 recordsLinked to original sources

PubMed1999

Connexin expression patterns in human trophoblast cells during placental development.

This study focuses on the gap junction expression pattern in trophoblast cells during human placental development in vivo and in vitro. Investigations of cell-cell communication properties within the subpopulations of trophoblast responsible for invasion, placental growth and feto-maternal transport seem of special interest because the intercellular channels are believed to coordinate proliferation and differentiation processes. From all gap junction connexins (Cx) investigated (Cx26, Cx31, Cx32, Cx37, Cx40, Cx43), Cx40 was the only connexin clearly detected within the cytotrophoblast of human placenta, and was restricted to the extravillous trophoblast of cell islands and cell columns. Most intense staining was found in the juxtastromal area correlated to the proliferating extravillous trophoblast cells. Connexin protein expression was missing during trophoblast migration into the decidua but was re-expressed in trophoblast aggregates within the decidua. Cx40 expression decreased with progressing pregnancy and no connexins could be detected in villous or extravillous trophoblast of mature placentae. In parallel, isolated trophoblast cells of first and second trimester placentae revealed Cx40 expression and, in contrast to the situation in vivo, Cx43 was also found. In isolated cells of mature placentae, expression of both Cx40 and Cx43 transcripts was decreased to low levels and Cx40 immunoreactivity was absent. Cx43 protein, however, was still detectable in trophoblast cultures of term placentae. Our studies suggest that Cx40 is the characteristic channel for the proliferating cell population of cell islands and cell columns of first and second trimester placentae and isolated trophoblast and is probably involved in regulation and coordination of the invasive pathway.

Cell Division↗

PubMed1995

Relative contributions of voluntary apnoea, exposure to cold and face immersion in water to diving bradycardia in humans.

1. Diving or face immersion bradycardia is a well recognized but incompletely understood reflux which occurs in man and other mammals. 2. In order to investigate the contributions made by voluntary apnoea, face immersion in water and cold exposure, 18 normal subjects were exposed to these challenges separately and in various combination. 3. Tested individually, cold and apnoea caused significant reductions in heart beat (P < 0.01 and 0.002, respectively). Face immersion in thermoneutral water had no effect on heart rate. 4. The bradycardic effect of apnoea at maximal inspiration may be due to stimulation of pulmonary stretch receptors. 5. Cold exposure and voluntary apnoea applied simultaneously caused a summative effect but when tested with face immersion in water there was a synergistic response greater than the sum of individual responses. 6. The results confirm the bradycardic effect of apnoea and cold exposure, whereas immersion in thermoneutral water had little effect, a finding which has been disputed in the literature.

Adult↗

PubMed1994

Embryological development of the arterial system of the forelimb in Tupaia.

BACKGROUND: The arterial system of the upper extremities in man shows drastic developmental changes and many individual variations related to interspecific variations in primates. The ontogenetic development in Tupaia was examined from the viewpoint of comparative embryology. METHODS: Histological specimens of 39 embryos were observed and reconstructed in three dimensions using a computer program. Four adult animals were dissected and examined with angiography to ascertain the end stage of development. RESULTS: At the proximal end of the upper arm the deep brachial artery appears first as a concomitant vessel with the radial nerve. It becomes reduced in size and is succeeded by the posterior circumflex humeral artery, which is accompanied initially by the axillary nerve and finally by the radial nerve. The main arterial passageway to the fingers consists of the brachial and interosseous arteries during early development. The superficial brachial artery and median artery are formed later, and their connection becomes the main route of blood supply for the finger arteries up to the adult stage. The ulnar artery is formed at the end of arterial development to form the ulnar end of the superficial palmar arch. The superficial antebrachial arteries are also recognized. CONCLUSIONS: All the arterial elements of the forelimb in Tupaia are observed in a variety of primates, including man, and the characteristics of Tupaia are thought to represent the primitive conditions of the common ancestor of tree shrews and primates.

Angiography↗

PubMed1992

Computer-assisted 3D-reconstruction and statistics of the limbic system. 1. Computer-assisted 3D-reconstruction of the hippocampal formation, the fornix, and the mamillary bodies.

The hippocampal formation of eight perfusion-fixed human brains was examined using new methods according to stereotactic and morphometric principles (macrovibratome and computer-aided 3D reconstruction). The reconstructions form part of a neuroanatomical reference system (NeuRef). This reference system allows for 3D visualisation of the brain and its components on a computer graphic workstation, as well as for the presentation of the union set based on a neuroanatomical structure taken from this sample of brains. This retrievable knowledge of neurofunctional systems is important for the preoperative planning of neurosurgeons and the adjustment of radiotherapy.

Adult↗

PubMed1992

Computer-assisted 3D-reconstruction and statistics of the limbic system. 2. Spatial statistics of the hippocampal formation, the fornix, and the mammillary bodies.

A statistical method is described to show the distribution of neuroanatomical structures within a Cartesian coordinate system from any given number of examinations. The algorithm is based on polygons derived from the outlines of neuroanatomical structures in parallel canthomeatal-orientated cutting planes. These polygons are transformed in virtual voxels, rotated into the bicommissural coordinate system, and projected onto the three main planes of this coordinate system. Areas with the same probability for the structures examined are given in these planes. As an example this method is applied to the hippocampal formation and the results attained are shown.

Hippocampus↗

PubMed1991

[Three-dimensional reconstructions in neuroanatomy].

Computer-aided 3D reconstructions of neurofunctional systems and structures are generated as a reference for neuroimaging (CT, MRI, PET). The clinical application of these 3D reconstructions requires a coordinate system and conditions resembling the intravital neuroanatomy as far as possible. In this paper the neuroanatomical Reference System (NeuRef) of the Department of Neuroanatomy of Hannover Medical School is presented. This consists of methods to record brain structures from serial sections with minimal error (less than 1 mm) and to display 3D brain models derived from such a data base. In addition, NeuRef is able to generate sections through, for instance, the visual and pyramidal system and to transfer these data onto a corresponding CT image. Therefore, this method can serve as a diagnostic aid in neuroradiology, in operation planning, and radiotherapy. It can also be used in PACS.

Brain↗

PubMed1990

[Doctor's-office blood pressure, home blood pressure, ergometry blood pressure and 24-hour blood pressure. The correlations with the echocardiographic parameters of heart muscle mass].

In 62 untreated hypertensives (31 men, 31 women; median age 40 [17-57] years) blood pressures (BP) were measured in the doctor's office, at home (self-measured) and every 15 min during 24-hour monitoring (by portable automated oscillometry), the results being compared with echocardiographic measurements of ventricular septal thickness (VST), left ventricular muscle mass (LVM) and left ventricular mass index (LVMI), in 41 of them also during and 5 min after 100 W bicycle ergometry. In the total cohort, 24-hour values correlated better with diastolic VST (systolic: r = 0.706, P less than 0.00001; diastolic: r = 0.507, P less than 0.0001) than office BP (systolic: r = 0.381, P less than 0.01; diastolic: r = 0.177, not significant) and home BP (systolic: r = 0.477, P less than 0.0001; diastolic: r = 0.371, P less than 0.05). In the 41 exercised hypertensives the correlation with echocardiographic values was less close than with their 24-hour BP, but slightly better than with office and home BP. Systolic BP correlated better than diastolic BP with echocardiographic values. VST generally correlated better with BP than LVM and LVMI. It is concluded that (1) 24-hour BP values correlate more closely with LVM than any other noninvasive BP measurement; (2) VST is affected more by systolic than diastolic BP; and (3) VST more specifically reflects the influence of BP on myocardial structure than does LVM and LVMI.

Adolescent↗

PubMed1989

Nocturnal hypertension in renal failure, haemodialysis and after renal transplantation.

Diurnal blood pressure variations in 20 patients with advanced renal failure, 20 patients on chronic haemodialysis, and 21 renal transplant recipients were compared with those of matched control groups without renal disease, using 24-h ambulatory blood pressure monitoring. Whereas the blood pressure during the day (from 8 a.m. to 8 p.m.) was roughly the same in the patients compared with their respective control groups, during the night (from 8 p.m. to 8 a.m.) it was substantially higher in all patient groups. The differences between the mean daytime and night-time values were significantly lower in the patients (P less than 0.05 to P less than 0.001). The nocturnal blood pressure decrease may be attenuated or even reversed in renal failure, in haemodialysis and after renal transplantation. In a proportion of these patients, 24-h ambulatory blood pressure monitoring showed an elevated nocturnal blood pressure, which may require some modification of treatment.

Blood Pressure↗

PubMedDate not supplied

3D reconstructions of neurofunctional structures for neuroimaging.

An improved method for computer-aided 3D reconstruction of neuroanatomical structures derived from intracranially fixed human brains is demonstrated. The embedded brains are cut into slices. The sliced surfaces are photographed. The outlines of the neuroanatomical structures are drawn onto transparencies which are scanned. The surfaces of the structures are 3D reconstructed with the triangulation method. The cortical structures of the human brain are complex, resulting in possible ambiguities for triangulation which must be solved interactively. These surface reconstructions allow for 3D visualization of the brain and its components comparable with intravital conditions found in clinical neuroimaging.

Algorithms↗

PubMedDate not supplied

[Immunity of the populations of the USSR and East Germany to reference strains of influenza viruses and the characteristics of a new antigenic variant of the virus].

In 1985, a new epidemic variant of influenza virus, A/Berlin/6/85 (H3N2) was isolated which differed antigenically from the reference A/Philippines/2/82 virus. The results of the study of population immunity in adults and children of the USSR and GDR to these virus variants confirm the data on the continuing drift of virus A (H3N2).

Adolescent↗