L.D.H. and L.D.H. isoenzymes of the intra-uterine secretions of the cow during the estrous cycle

Uterine secretions were collected from 20 mature cows during estrus (day 0), metestrus (day 5), diestrus (day 10) and proestrus (day-1). Lactate dehydrogenase (LDH) and LDH isoenzymes activity were evaluated. No significant cyclic variations of LDH activity was found in the uterine secretions while the mean of the enzyme activity was higher during the estrogenic period of the cycle. The relative activity of LDH-1, LDH-2 and LDH-3 isoenzymes were higher during proestrus and estrus whereas LDH-5 activity was more important during metestrus. The LDH-3 seems to have the higher relative activity in uterine secretions of the cow.     

Pleuromeia from the lower triassic of the far east of the U.S.S.R.

Pleuromeia obrutschewii Elias from Russian Island (Russkiy Ostrov, near Vladivostok) is hardly distinguishable from the European P. sternbergii (Muenster) Corda. The sporangia are adaxial, filling spoon-like depressions of the megasporophylls which have sterile tips. P. olenekensis sp. nov. from the Olenek River (northeastern Siberia) has larger sporangia and much larger megaspores with three-layered walls. The outer layer (ectexosporium) is reticulate. It is assumed that in other species this layer is lacking due to imperfect preservation. Mature megasporophylls, when shed, have a buoy-like shape and are often deposited together with cephalopod shells. This suggests a special mechanism of propagation by means of megasporophylls dispersed by water currents. The cosmopolitan distribution of Pleuromeia points to weakened climatic zonation in the Early Triassic.     

Studies of metal-sugar complexes in the solid state by the 13C-n.m.r. c.p.-m.a.s. method

Several metal-sugar conjugates have been prepared. Chelate coordination complexes of copper(II) and zinc(II) were prepared from salicylaldimine ligands derived from combinations of methyl 3,4,6-tri-O-acetyl-2-amino-2-deoxy-β-d-glucopyranoside or 1,3,4,6-tetra-O-acetyl-2-amino-2-deoxy-β-d-glucopyranose and salicylaldehyde. Similar Schiff's bases were prepared from chitosan and complexed to copper(II). Cross-polarisation-magic angle spinning ¹³C-n.m.r. spectroscopy showed that paramagnetic ions have profound effects on the resolution obtainable and, at high concentration, result in broad, featureless spectra. In contrast, diamagnetic ions have little effect on the isotropic chemical shifts of the sugar chelates.     

Peptidergic transmission in the brain. III. Hippocampal inhibition by the amygdala.

The mechanism of arginine vasopressin (AVP) action in the rat hippocampus has been determined. The peptide activates inhibitory interneurons and constricts cerebral microvessels. In the whole animal, each of these direct actions has secondary consequences for the excitability of pyramidal cells. Recent studies have shown that a peptide similar to AVP mediates endogenous neurotransmission in the hippocampus. Here we report experiments showing that the endogenous peptide activates the same mechanisms as exogenously applied AVP. The endogenous AVP-like peptide has no effect on the presynaptic fiber volley, or on pure somatic and dendritic postsynaptic potentials. These results are taken to exclude presynaptic mechanisms as explanations for the peptide's action. The endogenously released peptide inhibits individual pyramidal cells in single unit recording and excites presumed interneurons, just as AVP itself is known to act. The endogenous peptide is released only by stimuli applied to a nucleus that contains immunoreactive AVP and projects to the hippocampus.     

Pohlia andrewsii J. Shaw in the U.S.S.R.

Abstract

P. andrewsii appears to be widespread in the arctic regions of the U.S.S.R. and also in mountains of southern Siberia, the Altai Mountains. Except in the mountains of Central and Northern Europe the range of P. andrewsii does not overlap with P. annotina and P. camptotrachela.     

An e.p.r. study of the non-equivalence of the copper sites of caeruloplasmin.

The two Type 1 (blue) copper-binding sites of caeruloplasmin were spectroscopically differentiated by the kinetic analysis of the e.p.r. spectra during the redox cycle. One blue copper, with a hyperfine splitting constant (A parallel) of 6.8 mT, which was rapidly reduced, was not reoxidized by oxygen, whereas it was reoxidized by H2O2. The other blue copper (A parallel = 5.8 mT), which was reduced slowly, was rapidly reoxidized by either oxygen or H2O2. A conformational change of the Type 2 copper was concomitant with the fast reduction of Type 1 copper, whereas its reduction occurred during the slow phase. This sequence of events was reversed in the reoxidation step, that is, the Type 2 copper reappeared rapidly as the species with altered conformation and reverted to the symmetry typical of the native state in the slow phase. The specific reaction of a blue-copper site with the H2O2 can tentatively be related to the established ability of caeruloplasmin to prevent 'oxidative' attack of proteins and lipids.