Limited use of chromosomal markers in prenatal diagnosis

By aid of fluorescent centromere markers in chromosome No. 3 it could be shown that crossing over in a translocation quadrivalent had occurred on two occasions in a father who is carrier of a 3/5 translocation. This case demonstrates that marker chromosomes cannot always be used to trace the parental origin of structurally abnormal chromosomes.

Destruction of phospholipids and respiratory-chain activity in pig-heart submitochondrial particles induced by an adriamycin-iron complex

Ferric ion complexes of the antibiotic and antitumor agent adriamycin support peroxidation of phospholipids in pig heart submitochondrial particles as judged by disappearance of polyunsaturated fatty acids, loss in extractable phospholipid, adriamycin-Fe3+-dependent oxygen consumption and formation of material with ultraviolet absorption. Peroxidation was stimulated to an extent of about 100% at low rates of NADH oxidation in the submitochondrial particles, whereas oxidation rates higher than 50 nmol NADH oxidized x min-1 x mg protein-1 appeared to protect the membrane lipids. NADH oxidase, NADH-cytochrome c reductase as well as cytochrome c oxidase activities in the submitochondrial particles were progressively inactivated during incubation with adriamycin in the presence of Fe3+ ions, whereas NADH-ferricyanide reductase activity remained fully stable.

NADH oxidation in phospholipid-enriched cytoplasmic membrane vesicles from Escherichia coli

NADH oxidation in Escherichia coli cytoplasmic membrane vesicles enriched in anionic phospholipids by de novo synthesis of lipid in the vesicles from acyl-CoA esters and sn-glycerol 3-phosphate has been studied. NADH-oxidase but not NADH-dehydrogenase activity was found to decrease during synthesis and accumulation of phospholipid in the vesicles. Density gradient fractionation showed that NADH-oxidase activity was reduced to approximately 30% in vesicles with a 3-6 fold increase in anionic phospholipid, whereas vesicles with a greater than 10-fold increase in phospholipid had virtually no NADH oxidase activity.

Morphological and functional differentiation in epithelial cultures obtained from human skin explants

The present study was undertaken to characterize primary epithelial cultures obtained from human skin explants as experimental systems for studies of the differentiation process. When human skin explants were incubated at 34-35 degrees C, fibroblastic growth was strongly inhibited, whereas the epithelial growth proceeded unchanged. The lateral growth of the epithelial cells could be divided into two phases - a migratory and a proliferative one. Only cultures incubated at 35 degrees C or below completed the morphological differentiation process before sloughing, whereas no qualitative difference in protein synthesis was observed between cultures incubated at temperatures from 33-37 degrees C. Cultured epidermal cells were labelled with 3H-thymidine and analysed by flow cytometry and cell sorting. Cells sorted from the S- and G2-phase populations were further analysed by autoradiography and a considerable heterogeneity as to the nuclear labelling was disclosed. A large fraction of S-phase cells were found to be totally unlabelled. The grain count distributions revealed similar cell cycle subpopulations as have been shown to occur in vivo. The relationship of these subpopulations to the differentiation process is discussed.

Fluorescein in human plasma in vivo

In connection with corpus vitreum fluorophotometric examinations fluorescein was injected iv and fluorescein in the blood stream was studied with respect to protein binding and elimination kinetics. It was shown by ultrafiltration that in blood obtained during the examination most of the fluorescein was protein bound, and only a minor fraction (10-20%) was free in the water phase. While the free fraction was approximately constant over a wide concentration range when studied in vitro the free fraction increased by a factor of about 2 during a 2 h examination period in vivo. The curve describing the elimination of fluorescein from blood showed a polyexponential decline course. The area under this curve showed only a small variation for the same normal person examined 3 times over a period of 6 months. The area under the bolus has a magnitude, which is 30-40% of that under the rest of the curve.

Selective inhibition of fibroblasts by spermine in primary cultures of normal human skin epithelial cells

Overgrowth with fibroblasts has been a major problem in the cultivation of normal human skin epithelium. In the present study it is shown that the addition of spermine to the culture medium in micromolar concentrations has a differential cytotoxic effect on fibroblasts allowing the cultivation of human skin epithelial cells in primary culture without fibroblastic overgrowth. Putrescine, another polyamine, is shown to be equally cytotoxic to fibroblasts and epithelial cells when added in millimolar concentrations; below this concentration range no cytotoxic effect could be demonstrated. This difference in cytotoxicity between spermine and putrescine is suggested to depend on the conversion of spermine, but not putrescine, and to highly cytotoxic products by an amine oxidase present in fetal bovine serum.

A model study of the tubuloglomerular feedback mechanism: effector site and influence on renal autoregulation

The effector site of the macula densa tubuloglomerular feedback mechanism was determined with a mathematical model of glomerular ultrafiltration. The feedback response was found to be mediated by an increase in the hydraulic resistance of the afferent arteriole, possibly accompanied by a slight decrease in the ultrafiltration coefficient of the glomerular membrane. The contribution of the tubuloglomerular feedback mechanism to the autoregulation of renal blood flow and GFR during increased arterial blood pressure was evaluated with a mathematical model of the kidney. The tubuloglomerular feedback system of the superficial nephron was found to be a less efficient regulator of renal blood flow and GFR than the remainder of the autoregulatory mechanism.

Renal function in streptozotocin-diabetic rats

Renal function was examined with micropuncture methods in the insulin-treated streptozotocin-diabetic rat. Kidney glomerular filtration rate was significantly higher in the diabetic rats (1.21 ml/min) than in the control group (0.84 ml/min) Nephron glomerular filtration rate increased in proportion to the rise in kidney glomerular filtration rate (diabetic rats: 37.0 nl/min; control rats: 27.9 nl/min). Likewise renal plasma flow was significantly higher in the diabetic rats (4.1 ml/min) than in the control group (3.0 ml/min). Glomerular capillary pressure was identical in both groups (56.0 and 56.0 mmHg, respectively). The proximal intratubular pressure was significantly reduced in the diabetic rats (10.4 mmHg; control value: 12.5 mmHg). The effective glomerular ultrafiltration coefficient was slightly but not significantly higher in the diabetic rats (0.027 nl s-1mmHg-1) than in the control group (0.023 nl s-1mmHg-1). Kidney weight was significantly higher in the diabetic rats (1.15 g; control rats: 0.96 g) while body weight was similar in both groups (diabetic rats: 232 g; control rats: 238 g). Calculations indicate that the increases in transglomerular hydraulic pressure, renal plasma flow and ultrafiltration coefficient of the glomerular membrane contribute about equally to the rise in glomerular filtration rate. The increases in the values of the determinants of glomerular filtration rate may be the result of renal hypertrophy. These studies suggest that this model provides a useful method for investigating kidney function in diabetes, which may have relevance for our understanding of the kidney abnormalities in human diabetes.

Cultivation at low temperature as a measure to prevent contamination with fibroblasts in epithelial cultures from human skin

A major problem in cultivating normal human skin epithelium is overgrowth of the epidermal cells by fibroblasts. In this report we show that it is possible to obtain pure epithelial cell cultures by lowering the incubation temperature to 32-33 degrees C. Whereas the epithelial growth proceeds unchanged at this temperature, the growth of fibroblasts is strongly inhibited.

A mathematical model of fluid transport in the kidney

A mathematical model of the rat kidney is developed from glomerular and tubular submodels. It is assumed that all nephrons are identical, that the hydraulic pressure in the tubules obeys Hagen-Poiseuille's law, that the rate of fluid reabsorption depends on the flow rate of tubular fluid, and that the tubules are distensible. The independent variables of the model are selected to comply with experimental measurements in the hydropenic rat. The model is used to evaluate the mechanism of glomerulotubular balance: changing the mean ultrafiltration pressure to the glomerular capillaries has a substantial influence on glomerular filtration rate (GFR). A change in the rate of fluid reabsorption in the proximal tubules has a strong influence on GFR notwithstanding that the change in GFR is smaller than that in the rate of fluid reabsorption. The calculated values for the hydraulic pressure profile in the tubular system and the interstitial pressure during ureteral obstruction are in close agreement with experimental measurements. Increasing the arterial haematocrit above normal causes a substantial decrease in GFR, whilst reducing it below normal has only a small effect on GRF.

A bisatellited marker chromosome in an infant with the caudal regression anomalad

An infant with the caudal regression anomalad is described. Karyotypic analysis revealed mosaicism for a bisatellited microchromosome. Using banding techniques, an attempt was made to further identify the marker chromosome. It is suggested that a causal relationship exists between the cytogenetic findings and the clinical observations.

Influence of intratubular pressure on proximal tubular compliance and capillary diameter in the rat kidney

Tubular compliance is the response of tubular diameter to changes in intratubular pressure [7]. Proximal tubular compliance was determined directly by measurements of tubular diameter and pressure and indirectly using a mathematical model of tubular fluid flow based on measurements of the hydraulic pressure gradients along the tubule under free flow conditions and during an induced pressure reduction at the end of the proximal tubule. The two independent methods yielded similar values for compliance. Proximal tubular compliance was found to depend upon the intratubular pressure: tubular compliance was significantly higher (P less than 0.001) when the intratubular pressure was reduced below normal (1.0 micron cm H2O-1) than when the pressure was increased above the control value (0.4 micron cm H2O-1). Almost identical compliance values were measured in sodium pentobarbital and inactin anaesthetized rats (P greater than 0.8). Intratubularpressure changes resulted in inverse changes in the diameters of the adjacent capillaries, suggesting that the peritubular capillaries are distensible structures.

Continuous measurement of flow rate and volume in the nanoliter range

A simple transducer which is based on changes of electrical capacity with volume is described. The system accomodates fluid volumes of several microliters and the resolution is below one nanoliter. The response time of the transducer is about 10 ms. The system is applicable for continuous recording of flow rates in renal collecting tubules. Pulsatile flow in the duct of Bellini is demonstrated.

The interstitial cells in the renal medulla of rat, rabbit, and gerbil in different states of diuresis

The inner zone of the renal medulla of rats, gerbils, and rabbits was investigated to determine whether or not there are any characteristic ultrastructural differences between the interstitial cells of these species. The effects on the interstitial cells of water deprivation and water loading were also investigated. In all three species, the Type 1 interstitial cells, the lipid containing cells, were abundant and their distribution and topographical relations as well as their general ultrastructure were similar. The previously reported significantly higher frequency in desert rats could not be confirmed. Although the lipid droplets of the interstitial cells were smaller in gerbils and rabbits when compared to rats, their fine structure was similar. Their electron dense outer zone was sometimes associated with a granular material and/or a lamellar material with a periodicity of about 40 A resembling phospholipid "myelin figures". Water-loaded rats showed a considerable increase in the number of lipid droplets when compared to dehydrated or untreated animals. In contrast, the interstitial cells of waterloaded gerbils and rabbits were depleted of lipid droplets.

Angiotensin II induced reduction of peritubular capillary diameter in the rat kidney

Large peritubular capillaries were infused consecutively (20 nl-min-1) in random sequence with isotonic saline and angiotensin II (20-80 ng-ml-1). The diameters of the infused capillaries were measured, without knowledge of the infusate used, from colour photographs of the infused area. Angiotensin II induced a significant (p less than 0.001) decrease in capillary diameter (delta = 1.2 +/- 0.2 (SE) micron and delta = 2.1 +/- 0.2 (SE) micron with 20 ng-ml-1 and 80 ng-ml-1 angiotensin II infusates, respectively). This decrease was shown to be independent of external tubular compression: separate experiments in which the surrounding tubules were collapsed by injection of oil blocks yielded similar results. The possibility that the observed reduction in diameter was caused by an angiotensin II induced change in capillary permeability to the staining solution was excluded, since the angiotensin II effect was unchanged when fluorescent dextran (mol. wt. 150 000) was substituted for lissamin green. These experiments indicate that peritubular capillaries contract actively when infused with angiotensin II.