Inhibition of mast cell chymase by eglin c and antileukoprotease (HUSI-I). Indications for potential biological functions of these inhibitors

Recombinant eglin c (originally isolated from the medical leech) and antileukoprotease (HUSI-I from human seminal plasma) were examined for their ability to inhibit the mastcell protease chymase. Both inhibitors react rapidly with the enzyme: when about equimolar concentrations (in the range of 10(-8) M) of chymase and HUSI-I or eglin c were incubated the complex formation was apparently at equilibrium after 1 or 5 min respectively. When a constant amount of chymase (approximately 3 X 10(-8) M) was incubated with increasing concentrations of inhibitor a concentration of HUSI-I of 7 X 10(-7) M was necessary to cause 50% inhibition of the initial enzyme activity, whereas 8 X 10(-8) M eglin c was sufficient. The dissociation constant of the chymase-eglin c complex was calculated to be 4.4 X 10(-8) M. These results are discussed with respect to the possible in vivo function of antileukoprotease as an inhibitor of mast cell chymase.     

The effects of aromatizable androgens,non-aromatizable androgens,and estrogens on gonadotropin release in castrated African catfish,Clarias gariepinus (Burchell)

Summary To study the feedback mechanism of gonadal hormones on GTH secretion in male African catfish, the effects of castration and steroid replacement on GTH release, pituitary GTH content, and ultrastructural appearance of gonadotropes were investigated.Castration resulted in an increase in plasma GTH levels, a decrease in pituitary GTH content, and a degranulation of many gonadotropes. The aromatizable androgens testosterone and androstenedione were able to abolish the castration-induced increase in plasma GTH. This was accompanied with a restoration of pituitary GTH content and a regranulation of gonadotropes. The non-aromatizable androgens 5-dihydrotestosterone and 11-hydroxyandros tenedione did not have these effects. Replacement with estrone or estradiol resulted in an increase in pituitary GTH, however, without abolishing the elevated plasma GTH levels; ultrastructurally, many gonadotropes showed a welldeveloped granular endoplasmic reticulum together with a regranulation.The results of the present study indicate the significance of androgen aromatization in the feedback mechanism of gonadal steroids on the brain-pituitary axis.     

Gravity as an orientation guide during web-construction in the orb spiderAraneus diadematus (Araneae,Araneidae)

summary The effect of gravity on the web building behaviour of the common garden spiderAraneus diadematus was studied in three ways: (i) frames with partially completed vertical webs were swivelled into a horizontal position, (ii) by rotating frames with spiders in a vertical klinostat (1 rpm), and (iii) by vertically rotating a partially completed web treadmill fashion keeping the building animal in a certain position in space.(i) In the horizontal, radial wheels are not constructed, however, a more or less irregular spiral is added to a completed wheel; (ii) in the klinostat the radial wheel lacks the up/down distinction of normal webs, and the spiral is irregular; (iii) in the treadmill the spiral course is abnormal, and the degree of deviation depends on the position of the animal. If the body axis is parallel to gravity the spiral path deviates to both sides of the norm. In ag perpendicular body position the path deviates predominantly to one side, spiralling sharply inwards towards the hub. The observations suggest that the cyclic changes in the body position of spiral-buildingAraneus are an important component of the animal's orientation during this phase of web-construction.     

Ecological effects of lime treatment of acidified lakes and rivers in Sweden

Effects on the aquatic biota of lime (CaCO₃) application in acidified lakes and streams were studied in a number of waters. After treatment, lime-sensitive species of mosses (Sphagnum spp.) decreased, but species such as Potamogeton natans and Myriophyllum alterniflorum seemed to be favoured. A few years after liming species composition and diversity of phytoplankton, zooplankton and benthic insect larvae were almost identical to that found in oligotrophic and non-acid lakes. Molluscs and benthic crustaceans may have difficulties recolonizing. Reproduction of remaining species of fish was successful as soon as pH increased. High survival of larvae and fry can result in some extremely rich year classes with slow individual growth. In most cases restocking of depleted fish stocks was successful.     

Processing of yeast mitochondrial RNA: involvement of intramolecular hybrids in splicing of cob intron 4 RNA by mutation and reversion

Revertants have been obtained from six mutants of the box9 cluster, which are supposed to be defective in RNA splicing as a result of alterations in a splice signal sequence. This sequence is in the 5' part of intron 4 of the cob gene, 330 to 340 bp downstream from the 5' splice site. Sequencing reveals that reversion to splicing competence is achieved by restoration of the wild-type box9 sequence; by creation of novel box9 sequences; and by introduction of a second site or suppressor mutation (sup-) compensating for the effect of the primary box9- mutation. The sup- mutation alters a sequence in intron 4,293 bp upstream from the box9- primary mutation. The box9 sequence and this upstream sequence can base pair to form an intramolecular hybrid in intron RNA in which box9- and sup- are compensatory base pair exchanges (G----A and C----U, respectively). Thus intramolecular hybrid structures of intron RNA are essential for RNA splicing.     

Epitopes of peptide 43-88 of guinea pig myelin basic protein: localization with monoclonal antibodies

Two monoclonal antibodies, one raised by immunization with mouse myelin basic protein (MBP) and the second raised by immunization with peptide 68-88 of guinea pig MBP, were compared with respect to specificity. The former antibody (15.32) cross-reacted completely with rat, guinea pig, human, and bovine MBP. It also reacted with peptide 43-88 from each MBP. The latter antibody (22.17) was nonreactive with MBP, but cross-reacted with peptide 43-88 from rat, human, guinea pig, and bovine MBP. When tested with small peptides derived from peptide 43-88, antibody 22.17 reacted with an epitope in the C-terminal region. Antibody 15.32 reacted with an epitope in the N-terminal half of the peptide. The data show that 22.17 reacted with a unique epitope associated only with free peptide, whereas 15.32 recognized an epitope common to both peptide 43-88 and MBP.     

Structural alterations in fibronectin correlated with morphological changes in smooth muscle cells

Nontransformed cultures of vascular smooth muscle cells proliferate until they form a confluent sheet of cells. Subsequently, the cells become reorganized to form multicellular nodules that are loosely attached to the substrate. The formation of nodules is facilitated by the addition of medium conditioned by nodular cultures. Nodulation is inhibited by the addition of fibronectin. Fibronectins derived from monolayer culture conditioned medium or from plasma are maximally effective while fibronectin isolated from nodular cell conditioned medium is inactive. Analysis by NaDodSO4-polyacrylamide gel electrophoresis reveals that the nodular cell fibronectin has a molecular weight that is about 20-30 kd less than that of monolayer cell fibronectin. Further, nodular cell conditioned medium contains an activity that can convert both plasma fibronectin and monolayer cell fibronectin to the lower molecular weight correlated with the loss of biological activity.     

Energy metabolism of medium-chain triglycerides versus carbohydrates during exercise

Medium-chain triglycerides (MCT) are known to be rapidly digested and oxidized. Their potential value as a source of dietary energy during exercise was compared with that of maltodextrins (MD). Twelve subjects exercised for 1 h on a bicycle ergometer (60% VO2 max), 1 h after the test meal (1MJ). The metabolism of MCT was followed using 1-13C-octanoate (Oc) as tracer and U-13C-glucose (G) was added to the 13C-naturally enriched MD. After MCT ingestion no insulin peak was observed with some accumulation of ketone bodies (KB), blood levels not exceeding 1 mM. Total losses of KB during exercise in urine, sweat and as breath acetone were small (less than 0.2 mmol X h-1). Hence, the influence of KB loss and storage on gas exchange data was negligible. The partition of fat and carbohydrate utilization during exercise as obtained by indirect calorimetry was practically the same after the MCT and the CHO meals. Oxidation over the 2-h period was 30% of dose for Oc and 45% for G. Glycogen decrements in the Vastus lateralis muscle were equal. It appears that with normal carbohydrate stores, a single meal of MCT or CHO did not alter the contribution of carbohydrates during 1 h of high submaximal exercise. The moderate ketonemia after MCT, despite substantial oxidation of this fat, led to no difference in muscle glycogen sparing between the diets.     

Ontogenetic development of the pineal organ,parapineal organ,and retina of the three-spined stickleback,Gasterosteus aculeatus L. (Teleostei)

The ontogenetic developments of the pineal organ, parapineal organ, and retina were studied by the use of light and electron microscopy in embryos and fry of the teleost, Gasterosteus aculeatus, from 60 to 168 h after fertilization. Sixty to 66 h after fertilization, the primordium of the pineal complex is discernible in the diencephalic roofplate; the parapineal anlage is located rostral to the pineal anlage. Photoreceptor cells endowed with outer segments are present in the embryonic pineal organ already after 72 h, whereas outer segments of retinal photoreceptors could not be demonstrated before 144 h (hatching occurs between 120-144 h). Furthermore, neuropil formations with synaptic specializations are present in the rostral part of the pineal organ 108 h after fertilization. At 72 h, the embryonic parapineal parenchyma is already differentiated into parapinealocytes, which give rise to the parapineal tract, and glia-resembling elements. Although parapinealocytes carry cilia (9 X 2 + 0), only a single outer segment of the photoreceptor type could be demonstrated in the parapineal organ of one adult stickleback. Photoreceptors present in the pineal organ of unhatched embryos are hardly involved in visual functions, but may already at this early developmental stage serve as photoneuroendocrine transducers.     

The Mechanism of Microbiological Leaker Spoilage of Canned Foods: A Review

S ummary : This review summarizes the work on the subject carried out mainly in the authors'laboratories but also in the associated laboratories of Metal Box Co. Ltd., London, and Plat Manufaktor, Malmö, Sweden. Special attention is paid to the mechanism of bacterial reinfection and how it is influenced by deviations in can construction or can handling procedures. Methods of preventing bacterial reinfection at the most critical points in the canning operation are considered and certain guiding principles are derived.