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Biomedical subjects

H J Gundersen

Publications and source records attributed to H J Gundersen.

At least 127 records · Page 7Linked to original sources
PubMed1978

Circadian and 30 minutes variations in serum TSH and thyroid hormones in normal subjects.

Ten normal young males were investigated in order to examine diurnal and short-term variations in serum TSH and serum thyroid hormones. In five subjects blood samples were obtained every 30 min during a 24 h period of daily life. A synchronous diurnal rhythm was found for free T3 and serum TSH with low levels in the day-time and higher levels at night. The mean increase from day to night was 15 and 140 per cent, respectively. There was a tendency to a similar rhythm in free T4, but the increase of 7 per cent fell short of statistical significance. In the other five men blood samples were obtained every 5 min in a 6 to 7 h period starting within the interval from 19.15 to 22.00 h. A significant regular variation with a cycle-length of half an hour was found in TSH, free T3 and free T4. This rhythm accounted for a significant part of the total variation in the levels of TSH, free T3 and free T4. The mean amplitude of the short-term variation is 13, 15 and 11 per cent of the mean level of the respective hormones. The data suggest a pulsatile release of hormones from the thyroid gland governed by a pulsatile TSH secretion.

Adult↗
PubMed1978

Estimators of the number of objects per area unbiased by edge effects.

A survey is given of principles for obtaining an estimate of the numerical density of profiles not biased by the edge effect in planar samples. Various practical problems of implementation of the principles are discussed. None of the methods represent the ideal combination of independence of assumptions concerning both profiles and frame as well as independence of information external to the frame. The counting rules usually employed in the determination of numerical density are biased and also unnecessarily complicated. For manual work only two unbiased principles apply. The choice between them is mainly determined by the ease by which they are implemented.

Histological Techniques↗
PubMed1977

A long-term diabetic autonomic nervous abnormality. Reduced variations in resting heart rate measured by a simple and sensitive method.

Three types of variation in resting pulse rate were measured, using simple and reproducible methods, in 44 young juvenile diabetics and 11 controls. Diabetics with few years duration of the disease showed normal values of both long-term and cyclic fluctuations, as well as of non-systematic, random variation from beat-to-beat. All three types of variation were reduced in long-term diabetics, and the reduction was in all cases correlated with the duration of diabetes. The decrease in non-systematic, beat-to-beat variation attained statistical significance after 5 to 10 years duration of diabetes. It is concluded that reduced variation in resting pulse rate is a long-term diabetic manifestation and that the decrease of non-systematic, beat-to-beat variations in diabetics is a useful indicator of functional abnormalities of the autonomic nervous system.

Adult↗
PubMed1977

Glomerular size and structure in diabetes mellitus. II. Late abnormalities.

A study of autopsy kidney material from six long-term diabetics and four controls was performed in order to elucidate the mechanism of the glomerular enlargement in long-term diabetics. The volume and the severity of the glomerular lesions were measured in each of a number of randomly selected, open glomeruli. The relative amount of solid material was taken as an expression of the severity of the glomerular lesion. In the long-term diabetics the volume of open glomeruli was almost doubled compared to that of controls and in the individual subject the enlargement was found to be inversely related to the relative amount of solid material in the glomeruli. This indicates that the enlargement of open glomeruli in long-term diabetics is due to a compensatory hypertrophy rather than to the excessive deposition of basement membrane material. The number of nuclei per open glomerulus was increased in long-term diabetics, but nuclear size was unchanged. Most of the long-term diabetics had a large number of occluded glomeruli and the individual, relative number of such glomeruli correlated closely both with the duration of diabetes above 15 years and the concentration of creatinine in serum. It is concluded that the destruction of glomeruli due to diabetic microangiopathy is compensated for some years by hypertrophy of the least affected glomeruli. This compensatory hypertrophy of glomeruli might well account for the preservation of renal funtion in long-term diabetics for a number of years despite the progressive basement membrane lesions of diabetic microangiopathy.

Adult↗
PubMed1977

Glomerular size and structure in diabetes mellitus. III. Early enlargement of the capillary surface.

The present electron microscopic study shows that the kidney hyperfunction in early diabetes can be due to a significant morphological change: an increased glomerular filtration surface. Applying standard stereological methods, the area of the peripheral wall of the glomerular capillaries was measured in biopsy specimens obtained from 7 patients with early diabetes and 7 controls.--An 80% enlargement of the capillary wall (the surface of the peripheral basement membrane) was found in the diabetics (2p=0.0096). Also the total area of the interface between the tuft and the urinary space was increased by 70% (2p=0.029). Since the thickness of the peripheral basement membrane is known to be unchanged in patients with early diabetes the finding of an increased area of the membrane implies that an increased quantity of basement membrane material is present in these patients. The significance of this phenomenon for the understanding of the metabolism of the basement membrane is discussed, and a working hypothesis is advanced for the pathogenesis of the diabetic microangiopathy.

Basement Membrane↗
PubMed1977

A new principle for simplified and continuous counting of radioactive samples: enclosure between adhesive tapes.

Radioactive samples are enclosed between two layers of adhesive, transparent tape. The double-tape is wound into drums and automatically fed through the 4pi counting apparatus. This system reduced the workload of mounting, storage and disposal to less than half and the adhesive tape used is fifteen times cheaper than the disposable plastic counting tubes usually employed. The risk of radioactive contamination is practically excluded.

Adhesives↗
PubMed1976

A new photostimulator and videopupillograph for quantitative neuroophthalmological studies.

A new photostimulator and an infrared videopupillograph are described. The light output from the photostimulator is quantitatively variable, and the beam of light is focused in the plane of the pupil to a spot smaller than the narrowest pupil, thus affording open loop conditions. The videopupillograph gives a direct and continuous measure of the area of the pupil. The importance of these features in quantitative neurophysiological studies is discussed.

Constriction↗
PubMed1975

Glomerular size and structure in diabetes mellitus. I. Early abnormalities.

The volume of the glomerular tuft and its components was estimated in juvenile diabetics at onset and after one to six year's duration of the disease. An enlargement of the glomerular tuft was demonstrated in the newly diagnosed diabetics. In these patients the volume of both the individual capillary lumina and of the individual glomerular cells was enlarged, whereas the number of cells was unchanged. Although a partial normalization is seen in diabetics after a few years' disease, such patients still have an elevated capillary volume. The possible relationship between these findings and the well-documented elevation of the glomerular filtration rate in diabetics is discussed. It is suggested that the mechanism behind the morphological and functional changes is either a pressure-induced unfolding of the capillary wall or an increase of the capillary wall area, but the present study permits no distinction between these possibilities.

Capillaries↗