Chronopharmacology of Captopril plus Hydrochlorothiazide in Hypertension: Morning Versus Evening Dosing

Blood pressure follows a strong circadian rhythm in normotensive people and in patients with primary hypertension. This may have several implications for antihypertensive therapy, including the time of dosing. For this reason we studied the influence of different dosing times on the antihypertensive effect over 24 h using ambulatory blood pressure monitoring (ABPM). We studied 13 male patients with moderate hypertension with controlled blood pressure over 12 months under a fixed combination of captopril and hydrochlorothiazide. The dosage of the combination therapy was then halved and given as one evening and then as one morning dose, each for 3 weeks. The combination therapy given twice daily showed a good 24-h antihypertensive effect after 12 months of treatment. During the following 6 weeks the mean 24-h blood pressure did not increase under half dosage, irrespective of whether under evening or morning dosing. However, mean daytime values (systolic and diastolic) of ABPM were significantly higher with evening dosing when compared both with full dosage and with half dosage given in the morning. The mean arterial blood pressure over 24 h showed the same differences as systolic and diastolic blood pressure, whereas heart rate was not significantly different between the three therapeutic regimens. ABPM seems to be an ideal method for chronopharmacological investigations under everyday conditions. Our study demonstrated significant differences in daytime blood pressure but not in 24-h blood pressure between morning and evening dosing of a fixed antihypertensive combination therapy.     

The action of ionizing radiation on DNA in the presence of quinacrine

It is shown by UV absorption and absolute fluorescence spectroscopy of solutions containing both DNA and quinacrine that the components experience mutual radio-protection due to scavenging of water radicals. From measurements at different ionic strengths it is inferred that quinacrine bound to DNA is more efficiently protected than the free compound. Furthermore, release of bound quinacrine from DNA is observed at higher doses.     

Subcellular distribution of histone-degrading enzyme activities from rat liver.

Chromatin prepared from liver tissue contains a histone-degrading enzyme activity with a pH optimum of 7.5-8.0, whereas chromatin isolated from purified nuclei is devoid of it. The histone-degrading enzyme activity was assayed with radioactively labelled total histones from Ehrlich ascites tumor cells. Among the different subcellular fractions assayed, only lysosomes and mitochondria exhibited histone-degrading enzymes. A pH optimum around 4.0-5.0 was found for the lysosomal fraction, whereas 7.5-8.0 has been found for mitochondria. Binding studies of frozen and thawed lysosomes or mitochondria to proteinase-free chromatin demonstrate that the proteinase associated with chromatin isolated from frozen tissue originates from damaged mitochondria. The protein degradation patterns obtained after acrylamide gel electrophoresis are similar for the chromatin-associated and the mitochondrial proteinase and different from that obtained after incubation with lysosomes. The chromatin-associated proteinase as well as the mitochondrial proteinase are strongly inhibited by 1.0 mM phenylmethanesulfonyl fluoride. Weak inhibition is found for lysosomal proteinases at pH 5. Kallikrein-trypsin inhibitor, however, inhibits lysosomal proteinase activity and has no effect on either chromatin-associated or mitochondrial proteinases. The higher template activity of chromatin isolated from a total homogenate compared to chromatin prepared from nuclei may be due to the presence of this histone-degrading enzyme activity.     

Assimilatory sulfate reduction in chloroplasts: Evidence for the participation of both stromal and membrane-bound enzymes

The reduction of sulfate in osmotically shocked chloroplastswas investigated. Like intact (i.e., Class a) chloroplasts,this type carries out the complete sulfate reducing process.The conditions for formation of the intermediate bound sulfiteand bound sulfide were examined. The amount of bound sulfideand bound sulfide formed from sulfate was proportional to theamount of chlorophyll. The Km of the overall reaction from sulfateto bound sulfite was 1.53 mmoles (at 500 µg chlorophyll).ATP was saturated at 5 mM over a concentration of 0.25 to 0.5mg chlorophyll. At higher concentrations of chlorophyll, nosaturation by ATP was observed. Cysteine formation showed anoptimum concentration for O-acetyl serine at 4 mM. After separation of the osmotically ruptured chloroplasts intoa soluble "chloroplast extract" and a paniculate "chloroplastthylakoid fraction," bound sulfite was formed from sulfate bythe thylakoid fraction but not by the chloroplast extract. Fromthe chloroplast extract, a protein of low molecular weight waspurified. It increased the amount of bound sulfite formed whena NADPH₂-regenerating system was present. (Received June 6, 1975; )     

Lipids in the proximal convoluted tubule of the cat kidney and the reabsorption of cholesterol

Summary Lipid deposits in the cat kidney are mainly located in the epithelium of the proximal tubuli contorti, particularly in the pars contorta. As the amount of fatty acids in the blood of renal arteries is higher than in renal veins, the lipid inclusions are likely to be formed in the proximal convoluted tubule. Whether fat occurring in the urine has been released from the nephron epithelium and the mode of this release remains obscure. The structural equivalent of lipid extrusion into the tubules has not been observed.Components of the tubular lipids include triglycerides, phosphoglycerides and cholesterol. The results of the digitonin-cholesterol reaction favour the assumption that cholesterol is eliminated in the glomeruli and pinocytotically reabsorbed by the brush border cells, this process possibly serving recycling of this compound. The dilated basal labyrinth and intercellular space contain perpendicularly oriented lipid accumulations that reach the basal lamina. The ultrastructure of the lipid storing cells of pars contorta reacting positively for phosphoglyceride and cholesterol is characterised mainly by bodies with marginal plates. As far as can be judged from their morphology, these bodies are interpreted as large peroxisomes. A special feature of the pars recta are dumbbell shaped bodies and elongated or cup-like mitochondria concentrically surrounding cytoplasmic areas, as well as a well-developed smooth ER. In what way the organelles of the brush border cells are involved in catabolic and anabolic processes as far as renal lipid metabolism is concerned remains to be answered.This investigation was supported by a grant from the Deutsche ForschungsgemeinschaftThis paper is dedicated in friendship to Professor Berta Scharrer (New York) on the occasion of her 70th birthday     

Single unit activity in the peripheral lateral line system of the cichlid fishSarotherodon niloticus L.

Summary The activities of single afferent fibers were recorded in the trunk lateral line nerve of the cichlid fishSarotherodon niloticus L. Using both electrophysiological recordings and neuroanatomical tracing techniques, the number, arrangement, and innervation of superficial (SNs) and canal (CNs) neuromasts were determined. Both, SNs and CNs, are innervated by several afferent fibers of different diameters and efferent fibers. The CNs and SNs are neuronally separated: afferent fibers which innervate both CNs and SNs were not found. Whereas the single CN is innervated by a separate set of afferent fibers, fibers innervating the SNs within rows often branched to reach all or several SNs. The SNs within a row were thus considered to form a functional unit. With the exception of SNs on the tail fin, functional units of neuromasts were in general topographically restricted to single scales.The majority of lateral line units had resting activity. On the basis of the time interval distribution of the resting activity, 4 types of units were classified: these were labelled irregular (type I), regular (type II), bimodal (type III) and silent (type IV). Type I was the most common type of resting activity (obtained in 47.8% of the recorded units). Units with this resting activity type were identified as afferents innervating either SNs or CNs. Units with resting activity of type II represented mostly afferents of CNs if their mean activity was high (around 40 imp/s). If the mean activity of this type was below 20 imp/s the units were unresponsive to local water movements and at least some were identified as efferent fibers. Resting activity of type III was found only in units originating from CNs. Only 4% of the units were silent (type IV). These units were often identified as injured neuromasts. Units originating from CNs show higher mean resting activity than those from SNs. For both SN and CN units, the mean discharge rate of the resting activity correlated with the sensitivity to stimulation for sinusoidal water movements.During stimulation of the neuromasts by sinusoidal water movements of small amplitude and different frequencies, the response characteristics of SN and CN units were determined by linear frequency analysis under steady state conditions. Most units responded linearly to small stimulus amplitudes. In this amplitude range the units' resting activity was modulated according to the stimulus frequency. Small stimulus amplitudes proportionally changed the amount of modulation but did not alter the phase of the response. CN and SN units that responded linearly produce differing frequency responses. Whereas CNs were most sensitive at frequencies of up to 200 Hz (center frequencies between 100 and 200 Hz), the center frequencies of SNs were distributed between 10 and 70 Hz with a maximum number at about 30 Hz. Bode plots for many CN and SN units indicated that the neuromasts were sensitive to the acceleration component of the water movement.The functional significance of the differences between the two types of lateral line neuromasts (SNs and CNs) were discussed.Abbreviations SN superficial neuromast - CN canal neuromast     

The specific radioactivity of glycolic acid in relation to the specific activity of carbon dioxide evolved in light in photosynthesizing sunflower leaves

Attached leaves of sunflower (Helianthus annuus L.) were exposed to ¹⁴CO₂ during steady-state photosynthesis for 2 to 30 min in 345 l/l CO₂ and 21% O₂ at 29° C and a light intensity of 1300 E m^-2s^-1. Glycolic acid was extracted with water and diethyl ether, and was determined in the aqueous residue by high-pressure liquid column chromatography. The relative specific radioactivity of the glycolic acid synthesized during photosynthesis reached about 100% after 30 min of photosynthesis and was almost equal to that of the CO₂ evolved during photorespiration, their ratio at all times being nearly one. These results provide strong in-vivo evidence that the glycolic acid is the substrate for CO₂ evolved by sunflower leaves in light.     

Untersuchungen zum Glyoxylsäurestoffwechsel vonBacillus fastidiosus Stamm 83

Zusammenfassung BeiBacillus fastidiosus, der Harnsäure und Allantoin über Glyoxylsäure abbaut, wurde der Glyoxylat-Stoffwechsel untersucht. Enzyme des Glycin-Serin-Weges, des Oxalat-Weges und des -Hydroxyaspartat-Weges waren in zellfreien Extrakten nicht nachweisbar. Das Enzym Glyoxylatcaboligase, welches die Synthese von Tartronsäuresemialdehyd (TSA) aus Glyoxylsäure katalysiert, war zwar in den Extrakten vorhanden,abereine nachfolgende Umsetzung von TSA über den Glycerat-Weg schien unwahrscheinlich, da keine Glyceratkinase nachgewiesen werden konnte. Allerdingswurde eine enzymatische Tautomerisierung von Enzymen, welche die Synthese von Pyruvat aus HP über Serin katalysieren,deutet darauf hin, daß die beobachtete enzymatische Umwandlung von TSA zu HP in diesem Organismus an der Synthese von C₃-Verbindungen aus Glyoxylat beteiligt ist.

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Glyoxylate metabolism was studied inBacillus fastidiosus, which is known to degrade uric acid and allantoin via glyoxylic acid. Enzymes of the glycine-serine pathway, of the oxalate pathway and of the -hydroxyaspartate pathway were not detected in cell-free extracts. Glycoxylate carboligase, which catalyzes the formation of tartronic semialdehyde (TSA) from glyoxylate was found to be present. A further utilization of TSA via the glycerate pathway appeared to be unlikely, since no glycerate kinase could be demonstrated. However, an enzymatic tautomerisation of TSA to hydroxypyruvate (HP) was observed in the extracts. Methods for the detection of this enzyme were described. The presence of enzymes, catalyzing the synthesis of pyruvate from HP via serine indicated that the observed enzymatic conversion of TSA to HP might participate in the formation of C₃-compounds from glyoxylate in this microorganism.

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Abkürzungen HP Hydroxypyruvat - TSA Tartronsäuresemialdehyd Ausug aus der Disseration von W. Braun: Untersuchungen zum Glyoxylsäurestoffwechsel und zur Substrataufnahme anBacillus fastidiosus DSM 83, Saarbrücken (1976)     

Hypopulvins,novel peptaibiotics from the polyporicolous fungus Hypocrea pulvinata, are produced during infection of its natural hosts

In order to investigate the significance of antibiotics for the producing organism(s) in the natural habitat, we screened specimens of the polyporicolous fungus Hypocrea pulvinata growing on its natural hosts Piptoporus betulinus and Fomitopsis pinicola. Results showed that a particular group of nonribosomally biosynthesised antibiotic polypeptides, the peptaibiotics, which contain the nonproteinogenic marker amino acid α-aminoisobutyric acid (Aib), was produced in the natural habitat by the fungicolous producer and, consequently, released into the host. Using liquid chromatography coupled to electrospray high-resolution mass spectrometry we detected especially 19-, but also 11-, 18-, and 20-residue peptaibiotics in the five infected specimens analysed. Structures of peptaibiotics found were confirmed by analysing the peptaibiome of pure agar cultures obtained by single-ascospore isolation from the specimens. The 19-residue peptaibols were determined as deletion sequences of the trichosporins B lacking the Aib residue in position 6. Notably, 26 of the 28 peptaibiotics sequenced were novel; therefore the name ‘hypopulvins’ was introduced. Considering not only the ubiquity of both the two host species but also the highly specific association between H. pulvinata and P. betulinus/F. pinicola, and the abundance of this fungicolous species in north temperate regions of the world, a decisive role for the peptaibiotics detected in this study is predicted, which may act as mediators of the complex interactions between the basidiomycetous host and its fungicolous ascomycete ‘partner’. Structural analogies of the hypopulvins, particularly with other 18-, 19-, and 20-residue peptaibiotics, suggest that the hypopulvins are forming transmembrane ion channels and could thus support the hypothesis of a parasitic lifestyle of the fungicolous producer.