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Biomedical subjects

L Ohlson

Publications and source records attributed to L Ohlson.

12 recordsLinked to original sources
PubMed1989

Normal collecting ducts: visualization at urography.

In 21 of 636 patients with normal renal function and without obstruction of the upper urinary tract, urograms showed that contrast medium filled thin cylindrical structures in the renal pyramids with the same course as that of the collecting ducts. The prevalence of cylinders when the low-osmolality contrast medium iohexol was used was 21 of 158 studies (13.3%) and with the high-osmolality contrast medium amidotrizoate, two of 529 studies (0.4%). The cylinders were more distinct and more numerous with iohexol, while with amidotrizoate most cylinders appeared as striations. The cylinders appeared within 4 minutes from the start of contrast medium injection and remained distinct for 35-50 minutes. The diameter of the cylinders varied between 0.05 and 0.30 mm; their course was almost straight and closely followed the shape of the pyramid. The cylinders proved to consist of the highly opacified collecting duct lumina. Their configuration indicated that a single cylinder might be an individual collecting duct, but conclusive evidence was lacking.

Adolescent↗
PubMed1989

Morphological dynamics of ureteral transport. I. Shape and volume of constituent urine fractions.

Ureteral transport was studied in 50 urinary systems by urography with video recording in the upright and recumbent positions using low-osmolality and high-osmolality contrast media. Morphometry and volumetry were applied to right urinary systems in which the urine-filled segments had a circular cross section at maximum peristaltic distension. The filling of the lumbar segment was composed of four fractions, each entering that segment by a specific mechanism: 1) the residual urine left behind by the preceding contraction ring, 2) the postcontraction injection from the pyelocalyceal system, 3) the extraperistaltic flow, and 4) the peristaltic injection produced by the pyelocalyceal contraction rings. The variations in the precontraction filling by fractions 1-3 and in the volume of fraction 4 gave rise to four types of transport. The junction between the lumbar and pelvic segments constituted a constant point of resistance to flow that prevented fractions 1-3 from entering the pelvic segment, the peristaltic injection into that segment being determined solely by the resistance at the junction and the volume of the bolus in the lumbar segment. Extraperistaltic flow to the bladder constituted a separate type of transport.

Adult↗
PubMed1989

Morphological dynamics of ureteral transport. II. Peristaltic patterns in relation to flow rate.

To study in the human the conditions for the flow regimes inherent in urinary systems with a dependence of the contraction interval on urine flow rate (boluses-in-contact, leaky-bolus, and open-tube flow regimes), 50 urinary systems were examined at low and high flow rates. Morphometry and volumetry were applied to eight urinary systems. The bolus frequently contacted the preceding contraction ring but the mechanisms differed categorically from that conventionally postulated. Thus the contraction interval proved independent of flow rate, leading to boluses in contact not only at high but also at low flow rates, which is impossible in flow-dependent urinary systems. Likewise, contact proved possible with small as well as large boluses. Furthermore, the contact was invariably interrupted at the points of resistance to flow, the total contact period being only 4% of the ureteral transit. Leaky-bolus flow and open-tube flow were absent. The flow regimes as conventionally defined thus proved to be absent from and inconsistent with normal human urinary transport.

Adult↗
PubMed1978

Effects of the pregnant uterus on the abdominal aorta and its branches.

The pregnant uterus was found to exert pressure upon the lumbar region with a maximum over the midline of the lordosis and diminishing laterally. Those parts of the arterial system formed by the aorta and its dorsal branches and displaceable at autopsy, were accordingly dislodged by the uterus, whereas the fixed parts were compressed. The pressure effects extended cranially during pregnancy. Symptoms of compression can be relieved by avoiding supine and prone positions.

Aorta, Abdominal↗
PubMed1978

Topography of ovarian veins in pregnancy.

The course of the ovarian vessels and the ureters in pregnancy was evaluated by a topographic coordinate system presented previously. The vein was found to be displaced with the artery, whereas the displacement of the ureters was distinct from that of the vessels. The vessels thus reflected both the pressure and traction transmitted from the uterus to the abdomen whereas the ureters reflected only the pressure applied to the posterior abdominal wall.

Female↗