Showing papers by "University of Münster published in 1972"

Cerebral pO 2 , pCO 2 and pH: changes during convulsive activity and their significance for spontaneous arrest of seizures.

Abstract: SUMMARY The present study on rats and cats aimed to clarify the role played by hypoxia, hypercapnia and acidosis in spontaneous arrest of seizures. 1) In most experiments cortical pO2 declined during seizure activity, whereas pCO2 increased. Occasionally, however, reverse reactions occurred. Since the increase in cortical blood flow varied over a wide range, it could account for the fact that gas tension did not always change in the same direction or to the same degree during a seizure. Cessation of seizure activity was independent of the degree and direction of the changes in gas tension. 2) When seizures were arrested by experimentally produced hypoxia, cortical and spinal neurons always showed a distinct depolarization. When convulsive discharges were suppressed by artificial increase in PCO2 most units were concomitantly hyperpolarized. 3) When seizures ceased spontaneously, both cortical and spinal neurons showed a steep re- and hyperpolarization, independent of concomitant fluctuations in local gas tension. The findings lead to the conclusion that the degree of hypoxia and hypercapnia usually encountered during prolonged seizure activity does not reach the critical level sufficient to depress seizure activity. It must be assumed that spontaneous seizure termination is based, primarily, on neuronal processes. RESUME Cette etude se propose de preciser, chez les rats et les chats, le role de l'hypoxie, de l'hypercapnie et de l'acidose dans l'arret des crises spontanees. 1) Dans la majorite des experiences, Ia pO2 au niveau cortical diminue pendant la crise, tandis que la pCO2 augmente, quoique occasionnellement, on ait observe le contraire. La tres grande variabilite de l'augmentation de la circulation sanguine cerebrale pouvait rendre compte du fait que pendant une crise, la tension des gaz ne changeait pas toujours dans le meme sens ou dans les memes limites. L'arret de la crise etait independant du degre et du type des modifications de la tension des gaz. 2) Lorsque les crises etaient arretees a la suite d'une anoxie provoquee experimentalement, on a toujours observe une depolarisation des neurones corticaux spinaux. Lorsque les decharges convulsives etaient supprimees par une augmentation artificielle de la pCO2, la majorite des neurones etait parallelement hyperpolarisee. 3) Lorsque les crises s'arretaient spontanement, les neurones du cortex et de la moelle montraient une rapide repolarisation et ensuite une hyperpolarisation independamment des fluctuations concomitantes de la tension des gaz. Ces donnees amenent a la conclusion que le degre d'hypoxie et d'hypercapnie qu'on observe habituellement pendant des crises prolongees n'atteint pas un niveau suffisant pour deprimer l'activite paroxystique. On doit en tirer la conclusion que l'arret spontane d'une crise est dua des processus nerveux.

The position of short and long loops of Henle in the rat kidney.

Abstract: To determine the histotopographical relations of short and long loops of Henle in the rat kidney single short and long-looped nephrons were marked by microinjection with a silicone rubber and subsequently traced in histological serial sections. Short loops of Henle, derived from both supericial and midcortical nephrons, follow a similar course and possess similar histotopographical relations. In the medullary rays of the renal cortex and in the outer stripe of the outer medullary zone both limbs of short loops of Henle are lying together, near to the corresponding collecting duct. At the transition of outer and inner stripes the descending limbs turn towards the bundles and descend in the bundle periphery juxtaposed to venous vasa recta. After looping back at the junction of outer and inner zones they change position and ascend distant from the bundles in the vicinity of collecting ducts. The straight proximal portions of long-looped nephrons directly penetrate the outer stripe transversing this zone in tortuous course. In the inner stripe, the thin descending limbs of long loops of Henle descend distant from the bundles among the ascending thick limbs. In the inner medullary zone, neither the descending nor the ascending thin limbs have an exactly defined constant histotopographical position. The long loops ascend straight through the outer medullary zone, usually near to a vascular bundle, and reach the convoluted portion without transversing the medullary rays. The regularity of the histological pattern in the outer medullary zone suggests that the arrangement of the loops may influence their function, whereas in the inner zone the histotopographical position of the loop limbs does not appear to be a functionally important parameter.

Dynamisches Verhalten und Kinetik der Kohlenmonoxid-Oxidation am Platin-Katalysator†

Abstract: Stort man in einem kontinuierlich betriebenen chemischen Reaktor einen stationaren Betriebszustand, so laufen nach Beseitigung der Storung die Betriebswerte normalerweise wieder in den urspriinglichen, stabilen Betriebszustand ein. Bei exothermen Reaktionen ist jedoch unter bestimmten Voraussetzungen [l - 51 ein instabiles Verhalten moglich. Dann stellt sich anstelle des instabilen Betriebswertes je nach Art der Instabilitat entweder ein anderer stabiler Betriebszustand (Zund/Losch-Vorgang) oder eine Grenzzyklusschwingung (oszillatorisches Verhalten) ein. Unter isothermen Bedingungen sind analoge Instabilitaten bei Reaktionen mit autokatalytischem Verhalten moglich [S - 81. Isotherme Grenzzyklusschwingungen konnen bei gekoppelten chemischen Umsetzungen mit autokatalytischem Charakter auftreten und wurden bislang bei biochemischen [9], organischen [lo, 111 und anorganischen [ 12, 131 Reaktionen beobachtet. Die im folgenden beschriebenen Untersuchungen zeigen, da13 bei der heterogenen Kohlenmonoxid-Oxidation an Platin unter isothermen Bedingungen ebenfalls sprunghafte und periodische Instabilitaten des Umsatzes auftreten. Die sprunghaften Instabilitaten lassen sich mit Hilfe der makroskopisch meBbaren Formalkinetik der Reaktion deuten. Die Ursache hierfiir ist die ,,negative" Reaktionsordnung beziiglich CO bei hoheren GO-Partialdriicken. Das Auftreten isothermer Grenzzyklusschwingungen des Umsatzes ist dagegen iiberraschend, weil bei der COOxidation im makroskopischen Sinne keine Parallel- oder Folgereaktionen auftreten. Fur dieses Verhalten mu13 daher die Kopplung der mikrokinetischen Teilschritte der Reaktion auf der Katalysatoroberflache einschlieBlich der vor- bzw. nachgelagerten Chemisorptions- bzw. Desorptionsschritte verantwortlich sein. Wie nachfolgend gezeigt wird, ist hierbei die besondere Form der CO-Chemisorption an Platin von ausschlaggebender Bedeutung. Eine Reihe von Autoren [14-191 weisen zwei verschiedene Chemisorptionsstrukturen des CO an der EdelmetallOberflache nach und deuten diese beiden verschiedenen Chemisorptionszustande des CO als ,,Linearstruktur" mit chemisorptiver Bindung an ein Platin-Oberflachenatom und als ,,Briickenstruktur" mit entsprechender Bindung an zwei Oberflachenatome. Hinweise auf den Bildungsmechanismus wurden bislang nur fiir das System Pd/CO gegeben [20]. ober den Bildungsmechanismus der Chemisorptionsstrukturen fiir das System Platin/Kohlenmonoxid haben wir an anderer Stelle [21] ausfiihrlich berichtet, im folgenden wird der Mechanismus deshalb nur kurz wiedergegeben. Zwischen den freien Oberflachenatomen (F), dem CO aus der Gasphase (CO,) und der Linearstruktur (COL) stellt sich das Chemisorptionsgleichgewicht

Methode der Spektralmomente für das Hubbard-Modell eines schmalen S-Bandes

Abstract: An improved approximation for the narrows-band model is proposed. We assume a “two-peak”-ansatz for the spectral density and fit the relative weights and the positions of the poles by equating moments. The one-particle energies, the general form of which has also been obtained by Roth and Tahir Kheli and Jarrett, are the same as the Hubbard-energies except for the appearance of an additional energy termB(k, — σ) which leads to a spin-dependent band shift.B(k, — σ) contains higher correlation functions which are also calculated by using spectral densities and spectral moments. The theory is applied to a simple cubic lattice in the strongly correlated limit.

[Growth of oocytes during previtellogenesis in the ovary of Bruchidius obtectus Say. (Coleoptera-Polyphaga)].

Abstract: Im ersten Teil der Arbeit werden die Ovariolen adulter Imagines von Bruchidius obtectus licht- und elektronenmikroskopisch untersucht. Durch den Nachweis von Nahrstrangen, die die Oocyten mit den Nahrzellen der Endkammer verbinden, konnte erstmals gezeigt werden, das Bruchidius telotroph-meroistische Ovariolen besitzt. Die Nahrzellen, deren Kerne kettenformige Nukleolen aufweisen, bilden bei den Imagines ein Syncytium, das von einem raumlichen Maschennetz aus interstitiellen Zellen stabilisiert wird. In den Oocytenkernen entsteht wahrend der Pravitellogenese eine Karyosphare, von der aus „Nukleolarkorper“, Binnenkorper und „segmentierte Langsstrukturen“ gebildet werden. Die „Nukleolarkorper“ und die kettenformigen Nahrzellnukleolen werden als multiple Nukleolen diskutiert.

Stofftransport im Ovar von Pyrrhocoris apterus L.

Abstract: Synthese und Transport von DNS, RNS und Proteinen in einem telotrophen Ovar wurden autoradiographisch untersucht. Das Vorkommen von Endomitosen in Kernen sich differenzierender Nahrzellen und des Follikelepithels konnen fur Pyrrhocoris bestatigt werden, desgleichen der Transport von hochmolekularer RNS von den Nahrzellkernen zu den Oocyten in der Phase euplasmatischen Wachstums. Ein Transport in jungere Oocyten erfolgt nicht. Ein Beitrag des Follikelepithels zur RNS-Versorgung der Oocyten wie er fur eine andere Wanze beschrieben wurde, ist bei Pyrrhocoris nicht feststellbar; gleichfalls im Gegensatz zu den Befunden an anderen Wanzen findet eine relativ schwache RNS-Synthese in allen Oocytenkernen statt. Protein wird mit unterschiedlicher Intensitat in der gesamten Ovariole synthetisiert und von den Nahrzellen in die Oocyten transportiert.

X-Linkage of Human α-Galactosidase

Abstract: A deficiency in α-galactosidase (α-Gal) activity–as measured aspecifically with the use of artificial substrates–is a regular feature in leucocytes and fibroblasts of patients affected by angiokeratoma corporis diffusum or Fabry's disease, a well-known X-linked trait in man1–4. Fibroblast clones derived from mothers of affected males exhibit either normal or deficient activity of α-galactosidase. This demonstrates that the deficiency of α-galactosidase is caused by an X-linked mutation, but does not necessarily prove that the structural locus for this enzyme is itself located on the X-chromosome.

Chromosomal aneuploidy in human spermatozoa

Abstract: Recently developed staining techniques have made it possible to recognize the Y and number 9 chromosome in human spermatozoan heads. Thus, the frequency of numerical aberrations involving these two chromsomes has become amenable to investigation in sperm. Y Chromosome. I t is well established that the distal portion of the human Y chromosome at metaphase fluoresces more intensely than the rest of the karyotype after quinacrine staining (Caspersson et al., 1970). By this property the presence of the Y chromosome can also be demonstrated in the interphase of somatic cells (Pearson et al., 1970) at meiosis (Pearson and Bobrow, 1970) and in mature spermatozoa (Barlow and Vosa, 1970). The objective of the present study (Pawlowitzki and Pearson, 1971) was to count spermatozoa with two Y bodies in a series of fertile men in order to estimate the frequency of meiotic errors involving the Y chromosome in the normal male population. A total of 10.692 spermatozoa obtained from ejaculates of 12 normal fertile healthy males were examined. 5 of these (individuals No. 7 t2 , Table t) w e r e donors of a sperm bank 1, their semen had been stored for periods up to several months in liquid nitrogen at temperatures of ~ 190°C before investigation. The technique of the fluorescent examination (Pearson and Bobrow, 1970) and the criteria of counting sperm and fluorescent bodies (Pawlowitzki, Habflitationsschrift, 1971) were described elsewere in detail. The results are shown in the table: 54.6% of the examined spermatozoa had no fluorescent body, presumably being X bearing sperm. In 43.9% a single fluorescent body was seen, which are considered to be Y bearing sperm. 1.3% had 2 fluorescent bodies and therefore are believed to contain a supernumerary Y chromosome. Giant forms with 2 fluorescent bodies (0.2%) were counted separately, since these may be polyploid (Sumner, 1971; Pawlowitzki and Bosse, 1972). The contribution of polyploidy to sperm with doubled Y bodies appears to be about 1 in 7. Our results on the frequency of YY gametes in healthy fertile men are in good agreement with the results of other studies: Pearson and Bobrow (1970) found 1.4% spermatids with 2 fluorescent bodies each in testicular tissue of 3 normal

Relations between Cortical DC Shifts and Membrane Potential Changes of Cortical Neurons Associated with Seizure Activity

Abstract: It is well established that seizure activity of the cerebral cortex is accompanied by slow potential changes which have been labelled as “steady” or “DC” potential shifts. With generalized seizure discharges or direct recordings from an active focus, these potential deviations are usually surface-negative in polarity and finally turn over to a positive deflection which corresponds to the post-ictal silent period (for references see O’Leary and Goldring 1964, Caspers and Speckmann 1969, Gumnit et al. 1970).

Sulphur-dioxide induced bronchial hyperreactivity against acetylcholine.

Abstract: The effect of sulphur-dioxide (SO2) on the bronchial reactivity against acetylcholine (ACH) is carried out on 25 dogs. The dogs were exposed initially to acetylcholine aerosol, then to SO2 for 1 hr and again to ACH. 3 such cycles were repeated. The concentration of SO2 used were 1, 2, 5 and 10 ppm and the controls were given room air in place of SO2. The parameters studied were intrathoracic pressure as the indicator of bronchoconstriction, blood oxygen and carbon-dioxide, tidal volume, respiratory rates and arterial blood pressure. All the SO2 exposed animals have shown a significant increase of bronchial sensitivity than those of the controls. Maximum sensitization was induced by 2 ppm. The reaction provoked by 1 and 5 ppm were almost of the same order and little smaller than 2 ppm but greater than those produced by 10 ppm. The peak reactions against ACH observed for 1, 2 and 5 ppm were 3, 2 and 1 hr of exposure, respectively. After attaining the peak points, the reactions declined in all the 3 groups. But no such trend was obtained for those animals exposed to 10 ppm of SO2. The role of small concentration of SO2 as bronchial sensitizing agent against ACH is discussed.

Quantitative Untersuchungen zum Dotterprotein-Haushalt der Honigbiene (Apis mellifica)

Abstract: Die loslichen Hamolymph-, Ovarund Eiproteine der Honigbiene wurden elektrophoretisch auf Celluloseacetat-Streif en und Polyacrylamid-Gelen aufgetrennt. Die dominierende Hamolymph-Fraktion (60–80%) ist ein Weibchen-spezifisches Protein. Korrespondierende Fraktionen sind im Ovar und in ungefurchten Eiern zu finden. Aufgrund verschiedener Ergebnisse wird es als sehr wahrscheinlich angesehen, das diese Fraktionen das Dotter-Material (= Vitellogenin) repr⇒entieren. Bei Apis besteht das Vitellogenin nur auseiner Protein-Bande ohne Kohlenhydrat-Komponenten.

Autoradiographische Untersuchungen zur RNS- und Protein-Synthese in der frühen Embryogenese vonMusca domestica

Abstract: 1) An Eiern vonMusca domestica wurde der3H-Uridin-Einbau inde novo gebildete RNS autoradiographisch untersucht. In gleicher Weise wurde mit einem3H-AminosAure-Gemisch die Proteinsynthese bestimmt. 2) Die erste embryonale RNS-Synthese wurde nach dem 10. Teilungsschritt der Furchungskerne gefunden. 3) Eine Proteinsynthese findet sowohl in reifen Oocyten wie in frisch abgelegten Eiern statt. Die Syntheserate steigt bei den befruchteten Eiern vom Eintritt der Kerne in das Periplasma an und erreicht mit der Vollendung des Blastoderms ein Niveau, das bis zur Keimblattbildung erhalten bleibt. Bei den unbefruchteten Kontrollen ist die Markierung unmittelbar nach der Ablage hoher als bei den befruchteten Eiern. Sie nimmt mit zunehmendem Alter der Eier kontinuierlich ab. 4) Die Markierung liegt nach der Ablage gleichmA\ig verteilt uber dem ganzen Ei. Mit fortlaufender Entwickliung wird sie im Bereich des Blastams stArker als im Eiinnern. Im hinteren Polplasma wird unabhAngig davon bereits vor dem Eintritt der Furchungskerne eine stArkere Proteinsynthese gemessen als in den ubrigen Periplasmabereichen. 5) Unmittelbar vor Beginn der Organanlagen-Differenzierung ist eine regionspezifische Proteinmarkierung der Kerne zu beobachten. 6) Die Bedeutung der mutterlichen Matrizen fur die Proteinsynthese im jungen Ei und fur die Determination einzelner Keimbreiche wird diskutiert. Das Einsetzen der RNS-Synthese und der gleichzeitige Anstieg der Proteinsynthese werden als embryonale DifferenzierungsvorgAnge gedeutet. Im Bereich der Polplasmas wird eine determinative Rolle dort gespeicherter, mutterlicher RNS angenommen.

Pattern of luminal diameter changes along the descending and ascending thin limbs of the loop of Henle in the inner medullary zone of the rat kidney.

Abstract: Long loops of Henle in rat kidneys fixed during an osmotic diuresis were marked by microinjection with a silicone rubber. In histological serial sections corresponding descending and ascending thin limbs in the inner medullary zone were identified and their luminal diameters measured.

Autoradiographic Studies on RNA and Protein Synthesis in the Early Embryogenesis ofMusca domestica

Abstract: 1) 3H-Uridine incorporation into the RNA of eggs ofMusca domestica was measured by means of autoradiography. In addition, protein synthesis was studied by measuring incorporation of3H-amino acids. 2) The onset of embryonic RNA synthesis was found to occur after the 10. division of the cleavage nuclei. 3) Protein synthesis occurs in mature oocytes as well as in freshly laid eggs. The rate of synthesis in fertilized eggs begins to increase when the cleavage nuclei penetrate the periplasma. At the end of blastodermal development, the rate of protein synthesis reaches a value which remains constant until differentiation of the germ layers. Immediately after deposition of the eggs, the rate of incorporation of3H-amino acids is higher in unfertilized eggs than in fertilized ones. 4) At oviposition the radioactivity is uniformly distributed over the whole egg. During further development more radioactivity is accumulated in the periplasm than in the inner part of the egg. Already before penetration of the cleavage nuclei, a higher rate of protein synthesis is observed in the posterior pole-plasm than in any other part of the periplasm. 5) Immediately before the beginning of organogenesis, a region specific incorporation of3H-amino acids into nuclei can be observed. 6) The rOle of the maternal RNA in protein synthesis in the developing egg as well as its rOle in the determination of certain egg regions (especially of the posterior pole-plasm) is discussed. The beginning of RNA synthesis and the simultaneous increase in the rate of protein synthesis are interpreted as processes of embryonic differentiation. It is assumed that the maternal RNA stored in the pole-plasm has a determinative function.

Quantitative investigations on vitellogenic protein metabolism in the honey bee (Apis mellifica)

Abstract: The soluble proteins of the haemolymph, ovary and eggs of the honey bee were separated by electrophoresis on cellulose acetate foils and on polyacrylamide gels. The predominant haemolymph fraction (60-80%) is a female-specific protein. Corresponding fractions are found in the ovary and in uncleaved eggs. According to the results, it is highly probable that these fractions represent the yolk material or vitellogenin. InApis, this vitellogenin is represented by only one protein band which carries no carbohydrate components.The haemolymph titre of vitellogenic protein depends on the physiological state of the female bees. In the worker bees, haemolymph yolk proteins are detectable only during the nurse age, whereas in queens they can be found throughout the year. It may be noted that in the mated and egg producing queens the concentration of vitellogenin in the haemolymph is lower than in virgin queens and in adult non-laying queens.The rate ofin vivo protein synthesis was determined by injecting a mixture of14C-amino acids and measuring the radioactivity in pherogram bands using a methane flow counter. In the actively laying queen the rate of vitellogenin synthesis is 3 times higher than that of the non-sex-specific blood proteins. Approximately 85% of the labeled proteins which are released from the fat body are yolk material. In contrast to other insects, non-laying queens were also found to synthesize vitellogenin; however, the rate did not exceed that of the other serum proteins. The fate of yolk material in such females is unknown. In the ovary, synthesis of the euplasmic proteins occurs at a rate similar to that of the nonspecific haemolyph fractions. The appearance of radioactivity in the ovarian yolk is delayed compared with all other proteins. This indicates that these proteins are labeled byde novo synthesis, whereas the yolk is not built up within the ovary. This conclusion is further supported by the fact that the increase in specific radioactivity of ovarian yolk proteins occurs at a time when free14C-amino acids are no longer available in the haemolymph. Following the maximum intensity of labelling of yolk proteins the specific activity declines. From the data it can be estimated that the period of vitellogenesis for a single follicle is 2 days; 2 additional days of maturation, during which glycogen synthesis and chorion formation occur, are required before oviposition.

F-CENTRES OF TWO TYPES IN BaFCl CRYSTALS.

Abstract: F-centres in X-irradiated and additively coloured tetragonal BaFCl single crystals have been studied. An F-centre at a fluorine site absorbs light polarized parallel to the crystallographic c-axis in a band at 438 nm and light polarized perpendicular to c in a band at 550 nm. A chlorine F-centre has a band at 532 nm (E ‖ c) and a double band at 440 nm (E ‖ c). This dichroism arises from the tetragonal surroundings of the F-centres. The splitting of the double bands is probably due to a dynamic Jahn-Teller effect. In an X-irradiated crystal there is a partial transformation of fluorine into chlorine F-centres. In additively coloured BaFCl predominantly fluorine type F-centres are formed above 300 °C in thermal equilibrium. F-Zentren in gerontgten und additiv verfarbten tetragonalen BaFCl-Einkristallen wurden untersucht. Ein F-Zentrum auf einem F-Platz absorbiert parallel zur kristallographischen c-Achse polarisiertes Licht in einer Bande bei 438 nm und senkrecht dazu polarisiertes Licht in einer Doppelbande bei 550 nm. Ein F-Zentrum auf einem Cl− Platz hat eine Bande bei 532 nm (E ‖ c) und eine Doppelbande bei 440 nm (E ‖ c). Dieser Dichroismus wird durch die tetragonale Gitterumgebung bewirkt. Die Aufspaltung der Doppelbande ist wahrscheinlich die Folge eines dynamischen Jahn-Teller-Effektes. In einem gerontgten Kristall wird eine teilweise Umwandlung von F(F−)- in F(Cl−)-Zentren beobachtet. In additiv verfarbtem BaFCl werden im thermischen Gleichgewicht oberhalb 300 °C fast ausschlieslich F(F−)-Zentren gefunden.