Adenosine triphosphate hydrolysis in rat dental tissues

Summary The purpose of this study was to try to differentiate histochemically between the various enzymes which may catalyze the hydrolysis of ATP in developing rat dental tissues. Freeze cut and freeze dried sections of molar and incisor teeth were incubated in lead capture-based media at pH 5.0, 7.2 or 9.4 with one of the following substrates: -glycerophosphate, AMP, ADP, ATP, AMP-PNP and tetrasodium pyrophosphate. To establish the enzymatic nature of the hydrolysis parallel sections were incubated after prior fixation in either formaldehyde or glutaraldehyde.By comparing the enzymatic stainings obtained with the various substrates and at the different pH: s, it was concluded that ATP can be visibly hydrolyzed in rat dental tissues by alkaline phosphatase (stratum intermedium, apical part of maturation ameloblasts, basal part of all ameloblasts, odontoblasts and subodontoblastic layer), specific ATPase (apical and basal parts of secretory ameloblasts) and ATP pyrophosphatase and/or adenylate cyclase (stratum intermedium, odontoblasts). Acid phosphatase, specific ADPase, 5-nucleotidase, inorganic pyrophosphatase, 3:5-cyclic-AMP-phosphodiesterase and adenylate kinase on the other hand, seem not to be engaged in the ATP hydrolysis to such a degree as to complicate the interpretation of the histochemical staining. The alkaline phosphatase part of the ATP hydrolysis appeared to be rather insensitive to aldehyde fixation, while the hydrolysis effected by specific ATPase and ATP pyrophosphatase and/or adenylate cyclase was extinguished after fixation with formaldehyde for 4 h or glutaraldehyde for 10 min.     

Prostaglandins,indomethacin and dysmenorrhea

Uterine contractility was recorded during the period of menstruation in six dysmenorrheic women. A variable high tonus was observed in each case. Uterine recordings were repeated during the subsequent menstruation following pre-treatment with indomethacin at an oral dose of 75 mg or 200 mg per day beginning one day before the expected onset of menstruation. A lower uterine tonus was found in all indomethacin-treated cycles. Complete alleviation of spasmodic pain was obtained in the six subjects. The endogenous concentration of 15-keto-13,14-dihydro PGF_2α was determined by the gas chromatography-mass spectrometry method and observed to be relatively high in women with dysmenorrhea.     

Kinetic characteristics of the sulfate self-exchange in human red blood cells and red blood cell ghosts

Summary The sulfate and the chloride self-exchange fluxes were determined by measuring the rate of the tracer efflux from radioactively labeled human red blood cells and red blood cell ghosts. The concentration dependence and the pH-dependence of the sulfate self-exchange flux were studied. In addition, the effects of some monovalent and divalent anions on the sulfate and the chloride self-exchange fluxes were investigated.The sulfate self-exchange fluxes saturate, exhibiting a concentration maximum at sulfate concentrations between 100 and 300mm (25°C). The position of the concentration maximum depends upon pH. At high sulfate concentrations a self-inhibition of the flux becomes apparent. The apparent half-saturation constant and the apparent self-inhibition constant at pH 7.2 were 30mm and 400mm respectively. Within the pH range of 6.3–8.5, both constants decreased with increasing pH. No saturation of the sulfate self-exchange flux was observed if the sulfate concentration was raised by substituting sulfate for isoosmotic amounts of a second salt (NaCl, NaNO₃, Na-acetate, Na-lactate, Na-succinate or Na₂HPO₄). Red blood cells and red blood cell ghosts display the same pattern of concentration responsiveness.The sulfate self-exchange flux exhibits a pH-maximum at about pH 6.2 (37°C). The location of the pH-maximum is little affected by variations of the sulfate concentration. The logarithmic plots (log vs. pH) revealed that the flux/pH relation can be approximated by two straight lines. The slopes of the alkaline branches of the flux/pH curves range from –0.55 to –0.86, the slopes of the branches of the curves range from 0.08 to 1.14 and were strongly affected by changes of the sulfate concentrations. The apparent pK's obtained from the alkaline and from the acidic branches of the flux/pH curves were about 7.0 and 6.0, respectively. Intact red blood cells and red blood cell ghosts display the same type of pH-dependency of the sulfate self-exchange flux.The sulfate self-exchange flux is competitively inhibited by nitrate, chloride, acetate, oxalate and phosphate. The chloride self-exchange flux is competitively inhibited by thiocyanate, nitrate, sulfate and phosphate. The inhibition constants for the various anion species increase in the given sequence.The results of our studies indicate that the sulfate self-exchange flux is mediated by a two-site transport mechanism consisting either of a mobile carrier or a two-site pore. The experiments reported in this paper do not permit distinguishing between both transport mechanisms. The similarities of the sulfate and the chloride self-exchange flux and the mutual competition between sulfate and chloride point to a common transport system for both anion species.     

Solutions to a degenerate system of parabolic equations from marine biology

Summary A system of parabolic and ordinary differential equations u _t = a ² u _xx + F(u, v, w), v _t = a ² v _xx + G(u, v, w),w _x = – k(u)w is studied which has been proposed by Radach and Maier-Reimer for the dynamics of phytoplankton and nutrient in dependence of light intensity. It is shown that there is a unique solution to this system satisfying given initial and boundary conditions. The solution depends continuously on the data. For specific nonlinearities F, G, and k bounds for the solutions are given.     

Über die Bildung von Bakterienhemmstoffen durch Cosmarium impressulum

1. An already published test method for detecting bactericidal substances in paper chromatograms was further improved. 2. In cultures of Cosmarium impressulum free from bacteria, two bactericidal substances were found in the ether extracts from the algae and two others in the extracts of the culture medium. The are active against some or all bacteria testes (Serratia marcescens, Pseudomonas fluorescens; Aerobacter aerogenes or Bacillus pumilus). 3. If the culture medium of Cosmarium or another desmidiale was inoculated with the test bacteria, a clear bactericidal effect was never observed. 4. Because the activity of the bactericidal substances of Cosmarium is only small and the formation is not constant, it is concluded that the water-soluble bactericidal substances of the alga are not the cause that epiphytic bacteria do not grow normally on Cosmarium.     

Transport of material between the nucleus,the chromatoid body and the golgi complex in the early spermatids of the rat

Summary The movement and transport of material between intranuclear dense particles, the chromatoid body and the Golgi complex have been studied in early spermatids of the rat. The analyses involved observation of living accurately identified cells, time-lapse cinemicrography and electron microscopy.The chromatoid body establishes transient contacts with intranuclear material during early spermiogenesis. The chromatoid body also makes contacts with the Golgi complex. It is suggested that the chromatoid body receives material from the nucleus during the postmeiotic period and participates in the early formation of the acrosomic system.This work was supported by the Finnish National Research Council for Medical Sciences. The authors are grateful to Mrs. Marita Aaltonen and Mrs. Raija Andersen for their skilful technical assistance     

Ein Modell zur örtlich-zeitlichen Signalübertragung im visuellen System des Menschen auf der Basis der linearen Systemtheorie kontinuierlicher Medien

Zusammenfassung Als Modell für die Übertragung örtlich-zeitlich variabler Helligkeitsmuster durch das visuelle System des Menschen wird ein dreidimensionales, homogenes neuronales Geflecht betrachtet. Die Ausbreitung der neuronalen Erregung erfolgt anisotrop in afferenter und lateraler Richtung und wird durch eine modifizierte Wärmeleitungsgleichung beschrieben, deren Hauptmerkmal ein regenrativer Signalanteil ist. Die zeitabhängige Lösung beschreibt u.a. die zeitliche Übertragungscharakteristik für flimmernde Gitter im gesamten Frequenzbereich. Die stationäre Lösung beschreibt die örtliche Übertragungscharakteristik für Gitter, wobei auch die Struktur rezeptiver Felder mit inhibitorischem Umfeld deutlich erkennbar ist. Die Struktur der Lösung läßt verstehen, wie sich mit zunehmender Tiefe im neuronalen Geflecht der Übergang von der Ortsselektivität zur Ortsfrequenzselektivität vollzieht.

---

A model for the spatial-temporal signal transmission properties of the human visual system based on the linear system theory of continuous media

In this paper, a three dimensional homogeneous neural web serves as a model for the transmission of spatial-temporal luminous pattern by the human visual system. The propagation of neuronal excitation in afferent and lateral direction is assumed to be anisotropic. It is described by a modified heat conduction equation a main feature of which is a regenerative signal component. The time-dependent solution describes f.e. the temporal transmission characteristics for flickering grids in the whole frequency range. The stationary solution contains the spatial transmission characteristics for grids as well as the structure of receptive fields with inhibitory surrounds. The structure of the solution makes it under-standable how the transition from spatial selectivity to spatial-frequency-selectivity develops with growing depth of the neuronal web.

     

Confirmation of linkage between the loci for HL-A and glyoxalase I

Summary Linkage analysis of 7 families with 30 children confirmed previous findings of the linkage between HL-A and GLO. Out of 28 families with 90 children the highest lod score value obtained was +8.887 (recombination fraction=0.1).Supported by the Deutsche Forschungsgemeinschaft.