Plasma Cortisol in the Horse,Diurnal Rhythm and Effects of Exogenous Acth

Peripheral blood plasma Cortisol concentration and its diurnal variation was measured in 4 horses. Mean concentration of Cortisol during 24 hrs. was 42 ng/ml (s ± 20 ng/ml). Peak values occurred at 6 a.m. and the lowest values were observed at about 6 p.m. (mean 65 ng/ml and 20 ng/ml, respectively). Long-acting ACTH at a dose of 150 i.u. was given by intramuscular injection to the 4 horses. Peak Cortisol concentrations markedly exceeding the prestimulation level were obtained between 2 and 4 hrs. after injection. During the immediate 24 hrs. after these peaks, the mean Cortisol level was markedly lower and the cyclic variation out of phase with the basal diurnal pattern. After a gradual adjustment during the second postinjection day, no differences could be seen between the 2 patterns on day 3 after injection.     

The intra-axonal transport of acetylcholine and cholinergic enzymes in rat sciatic nerve during regeneration after various types of axonal trauma

The proximo-distal intra-axonal transport of acetylcholine (ACh) and cholinergic enzymes (choline acetyltransferase, CAT, and ACh-esterase, AChE) in rat regenerating sciatic nerve was studied by accumulation technique. Four types of axonal trauma were performed: freezing with solid CO₂, crushing, ligating the nerve with remaining tight silk ligature, and cutting the nerve. Normal and sham-operated rats were used as controls. One to twenty-nine days later, the nerves were crushed about 15 mm proximal to the trauma. The nerve segment proximal to this crush was dissected out 12 hr later and assayed for ACh-content and enzyme activities. The increase in this segment 12 hr after crushing was taken as an indication of proximo-distal transport in the regenerating nerves. ACh transport did not seem to vary during regeneration as compared to controls. In contrast, the transport of both CAT and AChE was initially markedly depressed. Towards the end of the observation period (29 days), a recovery of CAT-transport occurred in all groups. Recovery of AChE-transport was marked in the freeze and crush groups. In the cut group no recovery was seen and in the ligated group only a small recovery occurred. Thus, in the nerves where regeneration was facilitated by the presence of intact connective tissue sheaths (freezing and crushing) recovery of transport occurred earlier than in cut or ligated nerves.     

Comparison of Light and Electron Microscopic Determinations of the Number of Bacteria and Algae in Lake Water

Determinations of the number of microorganisms in lake water samples with the bright-field light microscope were performed using conventional counting chambers. Determinations with the fluorescence microscope were carried out after staining the organisms with acridine orange and filtering them onto Nuclepore filters. For transmission electron microscopy, a water sample was concentrated by centrifugation. The pellet was solidifed in agar, fixed, dehydrated, embedded in Epon, and cut into thin sections. The number and area of organism profiles per unit area of the sections were determined. The number of organisms per unit volume of the pellet was then calculated using stereological formulae. The corresponding number in the lake water was obtained from the ratio of volume of solidified pellet/volume of water sample. Control experiments with pure cultures of bacteria and algae showed good agreement between light and electron microscopic counts. This was also true for most lake water samples, but the electron microscopic preparations from some samples contained small vibrio-like bodies and ill-defined structures that made a precise comparison more difficult. Bacteria and small blue-green and green algae could not always be differentiated with the light microscope, but this was easily done by electron microscopy. Our results show that transmission electron microscopy can be used for checking light microscopic counts of microorganisms in lake water.     

Covalent binding of an NAD analogue to liver alcohol dehydrogenase resulting in an enzyme-coenzyme complex not requiring exogenous coenzyme for activity.

1. The NAD analogue, N6-[N-(6-aminohexyl)carbamoylmethyl]-NAD, was covalently bound to horse liver alcohol dehydrogenase in a carbodiimide-mediated reaction and in such a way that it was active with the very same enzyme molecule to which it was coupled. 2. The degree of substitution, i.e. the number of NAD analogues per enzyme subunit, could be varied (0.3-1.6). In one preparation 1.6 coenzyme molecules were bound per subunit; the alcohol dehydrogenase activity of this preparation was 40% of the activity obtained after addition of free NAD in excess. 3. It was calculated that every fourth active site of this preparation was provided with a covalently bound functioning coenzyme analogue, and that this analogue had a cycling rate of about 40 000 cycles/h in a coupled substrate assay. 4. The presence of the covalently bound coenzyme made the active sites difficult to inhibit with a competitive inhibitor. For example, 10 mM AMP inhibited the activity of the preparation by 50% whereas a reference system containing native alcohol dehydrogenase was inhibited by 80% in spite of the fact that the reference system contained about 20 000 times as high a concentration of coenzyme.     

Fluorescence histochemistry of peptide hormone-producing cells: Observations on the nitroso-naphthol method for the demonstration of tyrosine residues

Summary Nitroso-naphthol reacts with tyrosine residues of peptides (and probably also proteins) to yield intensely fluorescent condensation products. This reaction forms the basis of a fluorescence histochemical procedure designed to demonstrate cells that are rich in tyrosine-containing peptides or proteins. In models the method was found to be specific for p-hydroxylated phenolic compounds. Fluorescence was induced also following formaldehyde vapour fixation. With the nitroso-naphthol technique the zymogen granules of gastric chief cells, intestinal Paneth cells, pancreatic acinar cells and certain peptide hormone-secreting cells such as the GH cells in the adenohypophysis, the insulin cells of the pancreatic islets and the calcitonin cells of the thyroid gave intense fluorescence with spectral characteristics indistinguishable from those of the fluorophores of tyrosine-containing peptides. In addition, a population of endocrine-like cells in the antral and intestinal mucosa of certain mammals displayed fluorescence.Grant support from the Swedish Medical Research Council (04X-04499)     

Effects of estrone, estradiol and estriol combined with dihydrotestosterone on mounting and lordosis behavior in castrated male rats

Prepuberally castrated male rats were injected with estrone (1 or 5 μg), estradiol (1 or 5 μg) or estriol (1, 5, or 25 μg) either alone or in combination with dihydrotestosterone, (0.5 mg). Each of these steroids, when given alone, had no or only weak stimulatory effects on male sexual behavior. When combined with dihydrotestosterone all estrogens stimulated full copulatory behavior, the order of potency being estradiol, estrone, and estriol. Lordosis behavior in response to male mounting or manual stimulation was facilitated by all estrogens. All estrogens caused a slight weight increase of the seminal vesicles, ventral prostate and glans penis.     

Effect of some antiestrogens and aromatase inhibitors on androgen induced sexual behavior in castrated male rats

The effect of antiestrogens (MER-25, ICI-46474, and cis-clomiphene) and aromatase inhibitors (5-α-androstanedione, metopirone, and aminoglutethimide) on androgen induced copulatory behavior was tested in sexually inexperienced castrated male tats. Daily injections of 1 mg testosterone (T) for 21 days induced sexual activity in most subjects (61% mounting). Daily pretreatment with MER-25 or cis-clomiphene at three dose levels did not block the behavioral response to T. ICI-46474 at the high dose level (1 mg/kg) elicited a significant depressory effect on the sexual behavior of the T treated castrated rats. A single injection of 6 mg testosterone propionate (TP) induced mounting behavior in 56% of the tested rats within 120 hr. Treatment with metopirone or 5 α-androstanedione (injections every 12 hr for 96 hr) did not inhibit the response to TP. By contrast, aminoglutethimide (5 or 15 mg every 12 hr for 96 hr) abolished the behavioral response to androgen.     

Studies on closure of the ductus arteriosus. XII. effect of indomethacin and sodium salicylate in rats and rabbits

Administration of prostaglandin synthetase inhibitors to pregnant does and dams in late gestation was followed by contraction of the fetal ductus arteriosus when studied by the whole-body freezing method. In the rat this contraction was well established within 6 h and persisted up to 36 h following 15 mg/kg indomethacin p.o. No effect was observed in the 18 d rat fetus but fetuses at 20 d and 22 d of gestation responded significantly to indomethacin. Doses of indomethacin approaching clinical usage (2.5 mg/kg) also caused a positive response . The rat was found to be sensitive also to sodium salicylate and in the rabbit both indomethacin and sodium salicylate were effective. Exposure to prostaglandin synthetase inhibitors with resulting contraction of the ductus may seriously disturb cardiac function in the fetus.     

Bimodal regulation of secretion by cytoplasmic Ca2+ as demonstrated by the parathyroid

Bovine parathyroid cells were used to study parathyroid hormone (PTH) release and the cytoplasmic Ca2+ concentration (Cai2+). When the extracellular Ca2+ concentration was decreased from 3.0 to 0.5 mM, perifused cells reacted with rapid stimulation of PTH release. However, a further reduction of extracellular Ca2+ to less than 10 nM resulted in prompt inhibition. Both effects were readily reversible. Using the intracellular Ca2+ indicator quin-2 also as a buffer for calcium it was possible to control Cai2+ within the 20-600 nM range. PTH release was found to increase with Cai2+ up to 200 nM but was gradually suppressed above this concentration.     

Sequential endocrine changes and behaviour during oestrus and metoestrus in repeat breeder and virgin heifers

The aim of the experiment was to study the oestrous behaviour and the peripheral blood plasma profiles of luteinizing hormone (LH), progesterone and the prostaglandin metabolite, 15-keto-13,14-dihydro-PGF₂, during oestrus and metoestrus in repeat breeder (RBH) and virgin heifers (VH). Ten animals of each category were utilized. The RBH had a history of at least three inseminations without conception, and the VH were sexually mature animals not previously inseminated or mated. Oestrous symptoms were recorded and blood collected from the onset of prooestrus to 7 days after oestrus. The animals were inseminated during oestrus and their embryos were collected by a nonsurgical technique 7 days after insemination. The morphology of the embryos was evaluated.

The duration of oestrus was longer (P < 0.05) in the RBH (31.5 ± 3.6 h) than in the VH (23.8 ± 2.0 h). No differences in duration of prooestrus or in the interval from the end of oestrus to postoestrous bleeding were found between the heifer categories. The interval from the onset of oestrus to the preovulatory LH peak was longer (P < 0.05) in the RBH (12.2 ± 2.8 h) than in the VH (4.8 ± 1.5 h). There was a lower LH release in the RBH than in the VH, measured as the magnitude of the preovulatory LH peak (P < 0.05; 28.0 ± 4.0 vs. 40.7 ± 3.6 μg/l) or as the area under the curve of the LH peak (P < 0.01; 1141 ± 164 vs. 1765 ± 144 mm²). The progesterone levels were higher (P < 0.05) in the RBH than in the VH during the interval 5–48 h and lower (P < 0.05) during the interval 121–168 h after the LH peak. Peaks of the prostaglandin metabolite were seen during oestrus in both heifer groups. There were more prostaglandin metabolite peaks in the RBH than in the VH during the interval 13–24 h after the LH peak. Fewer normal embryos (P < 0.05) and more degenerated embryos (P < 0.01) were found in the RBH than in the VH group 7 days after insemination. No apparent relation was found between the morphology of the embryos and the hormonal changes.

The result of the study indicates a hormonal imbalance in the RBH. The hormonal asynchronism starts before or early in oestrus, which presumably leads to a sequence of improper hormonal changes responsible for the elevated embryonic loss in repeat breeder animals.