Sequential Hormonal Changes in the Postpartum Dairy Cow

Peripheral plasma levels of 15-keto-13,14-dihydro-PGF2α, progesterone, Cortisol, LH and prolactin were studied in 6 primiparous postpartum dairy cows. The cows were followed by hormone measurements and clinical examinations from parturition until pregnancy was established. Blood was collected 3 times per day. The cervix, uterus and ovaries were examined by rectal palpation at 6–10 days intervals. The cows were observed for signs of oestrus twice daily and were additionally teased with a bull to provoke standing heat. Four cows had a normal parturition and dropped their fetal membranes shortly afterwards. (NR group). The remaining 2 retained their fetal membranes for more than 24 h following parturition (RFM group). One out of 6 cows showed standing oestrus at the first ovulation, 4 animals were in oestrus at the second ovulation and all cows showed signs of oestrus at the third ovulation. Although the length of the first luteal phase varied from 9 to 22 days a corpus luteum was in all cases palpated. The secretion of progesterone during the first luteal phase was terminated by a PGF2α release. A significant difference in 15-keto-13,14-dihydro-PGF2α levels between the 2 groups was found on days 0–4 (2.39 vs 6.87 nmol/1 at Ρ < 0.06). Postpartum prostaglandin F2α release as reflected by the level of 15-keto-13,14-dihydro-PGF2α lasted shorter in the NR group than in the RFM group (15–17 vs 21 days). Significant positive correlations between 15-keto-13,14-dihydro-PGF2α and Cortisol as well as between prolactin and Cortisol during the first 24 days postpartum were noted only in cows having normal parturition. The most pronounced daily prolactin variations occurred during the second luteal phase (NR group), when a significant difference between the times 8.00, 12.00 and 15.00 was recorded (14.7, 31.5 and 19.7 μg/l, respectively). Moreover, a partial negative correlation between log value of prolactin and arithmetical value of LH was found in these cows only during the first luteal phase after parturition.     

Progesterone determinations and clinical examinations of reproductive organs in purebred and crossbred female Zebu cattle

Five experiments were undertaken to investigate variation in progesterone concentrations as related to the collection and handling of samples of milk and blood, to determine reference values for progesterone and to evaluate clinical findings in relation to progesterone data from pure- and crossbred Zebu cattle reared in the Peruvian tropics. Whole-milk progesterone concentrations obtained from 12 Holstein x Nellore pregnant cows at hourly intervals over a 24-h period were highest immediately after milking; this peak was followed by a sharp drop over the next 3 h. Milk-fat content from 28 Brown Swiss x Nellore pregnant cows increased from 2.4% before milking to 6.7% afterwards (P < 0.05), whereas progesterone concentrations in whole milk increased from 18.4 to 59.5 nmol/1 (P < 0.05). Progesterone concentrations in fat-free milk were stable, with the exception of the fore-milk sample, which was lower than subsequent samples collected during milking (P < 0.05). Blood samples collected from 23 purebred, pregnant Nellore cows, were divided into four aliquots, and plasma and serum were harvested periodically over the next 120 h of storage at +4 degrees C, or in the shade at ambient air temperatures. The results indicate that blood samples can be stored unseparated at both temperatures studied for up to 3 h without severe loss of progesterone. Milk samples collected at different intervals during the luteal phase of the estrous cycle and during early and mid-pregnancy from crossbred cows showed no significant differences in progesterone concentrations between Days 9 to 13 of the cycle and Days 9 to 13 of gestation. Progesterone levels during advanced gestation were higher (P < 0.05). Out of 2,607 clinical examinations, the level of agreement between palpatory findings and progesterone determinations was 95.6 and 81.9% in diagnosing non-luteal and luteal structures, respectively. Significant differences in the level of agreement between palpators were found (P < 0.01). It is concluded that milk samples, preferably composite milk or strippings, must be consistently collected at the same stage of milking, and that centrifugation of blood samples should be done as soon as possible and not later than 3 h after collection.     

Endocrine profiles and embryo quality in the PMSG-PGF2alpha treated cow

Plasma progesterone and LH concentrations around estrus were determined for both PMSG treated (experimental animals) and non-treated (control animals) dairy cows and heifers of the Holstein Friesian and Jersey breeds, and these hormone profiles were related to the embryo quality. Most experimental animals experienced an increase in progesterone concentrations following PMSG treatment and an abrupt decrease to values below 3 nmol/l after PG injection. The mean (+/-SE) intervals from prostaglandin treatment to estrus were 46.9+/-1.8 h and 64.5+/-4.8 h for experimental and control animals, respectively. At the onset of heat the progesterone concentration in experimental animals with optimal embryo quality (group I) was significantly lower (p<0.01) than in experimental animals which yielded unfertilized eggs (group II) (1.2+/-0.1 versus 3.9+/-0.8 nmol/l) and significantly higher than the level in the control group (0.6+/-0.1 nmol/l). Following estrus the progesterone profiles in all 3 groups were studied and the length of the superovulatory cycle was measured to 26.0+/-4.8 days. The preovulatory LH surge occurred sooner after prostaglandin injection in experimental (41 h) than in control animals (65 h). The LH surge in group I occurred within a narrow range and reached a higher average level than group II (24.2+/-2.2 ng/ml and 16.3+/-3.7 ng/ml, respectively). The control group attained an even higher LH surge (31.8+/-8.8 ng/ml) than did the experimental animals. The data presented in this experiment indicate that plasma levels of progesterone and LH in PMSG-PGF(2)alpha treated animals are related to embryo or egg quality.     

Post-partum release of prostaglandin F(2alpha) and uterine involution in the cow

Peripheral plasma levels of the main blood plasma metabolite of PGF(2alpha) (15-keto-13,14-dihydro-PGF(2alpha)) and progesterone were investigated during the immediate, post-partum period in 59 normally calving cows. Uterine involution was monitored by weekly rectal palpations. The levels of the prostaglandin metabolite were high at parturition and remained thereafter elevated for periods varying up to 7-23 days. Uterine involution was completed during periods ranging from 16-53 days. According to the clinical findings, the animals were divided into three groups. Group A comprises 46 animals which had an uncomplicated, puerperal period. A significant (p<0.001) correlation between the duration of elevated prostaglandin levels and the time for completed uterine involution (Y=29.6 - 1.3 (X - 13.5)) was found for these animals. Group B animals (n=8) had periods of varying length with uterine discharge during the first 30 days post-partum. When compared to group A animals, the animals in group B had comparatively longer periods of prostaglandin release and also longer periods for completion of uterine involution. Group C animals (n=5) at times had palpable, thin-walled, cystlike structures in the ovaries during the first 30 days post-partum. In this group of animals, the periods of high prostaglandin levels, as well as for the completion of uterine involution, were similar to those for the animals in group A. Progesterone levels remained low during the immediate post-partum period and in no case were elevated levels found until the prostaglandin release had ceased.     

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.     

Temporal and spatial variation in coastal macrobenthic community structure,hanö bay (southern Baltic)

Quantitative (0.1-m²) samples of benthic macrofauna were taken at three depths (5, 10, 17 m) off the eastern coast of Scania, southern Baltic, in the period April 1974 to August 1978. Altogether 20 sampling cruises were made. Spatial and temporal species composition, abundance and biomass were compared. The number of species increased significantly with increasing depth. Zonation of the species was due to their zoogeographical origin and capacity to withstand exposure. Abundance was highest at 5 m depth whereas biomass increased with depth due to the dominance of large bivalves. Variation in abundance within years was large at all three depths and connected with reproductive recruitment for all species except Bathyporeia pilosa Lindström which migrated towards the shore in summer.     

Intrafusal myosin heavy chain expression of human masseter and biceps muscles at young age shows fundamental similarities but also marked differences

Muscle spindles are skeletal muscle mechanoreceptors that provide proprioceptive information to the central nervous system. The human adult masseter muscle has greater number, larger and more complex muscle spindles than the adult biceps. For a better knowledge of muscle diversity and physiological properties, this study examined the myosin heavy chain (MyHC) expression of muscle spindle intrafusal fibres in the human young masseter and young biceps muscles by using a panel of monoclonal antibodies (mAbs) against different MyHC isoforms. Eight MyHC isoforms were detected in both muscles-slow-tonic, I, IIa, IIx, foetal, embryonic, α-cardiac and an isoform not previously reported in intrafusal fibres, termed IIx′. Individual fibres co-expressed 2–6 isoforms. MyHC-slow tonic separated bag₁, AS-bag₁ and bag₂ fibres from chain fibres. Typically, bag fibres also expressed MyHC-I and α-cardiac, whereas chain fibres expressed IIa and foetal. In the young masseter 98 % of bag₁ showed MyHC-α cardiac versus 30 % in the young biceps, 35 % of bag₂ showed MyHC-IIx′ versus none in biceps, 17 % of the chain fibres showed MyHC-I versus 61 % in the biceps. In conclusion, the result showed fundamental similarities in intrafusal MyHC expression between young masseter and biceps, but also marked differences implying muscle-specific proprioceptive control, probably related to diverse evolutionary and developmental origins. Finding of similarities in MyHC expression between young and adult masseter and biceps muscle spindles, respectively, in accordance with previously reported similarities in mATPase fibre type composition suggest early maturation of muscle spindles, preceding extrafusal fibres in growth and maturation.     

Evidence for myofibril remodeling as opposed to myofibril damage in human muscles with DOMS: an ultrastructural and immunoelectron microscopic study

The myofibrillar and cytoskeletal alterations observed in delayed onset muscle soreness (DOMS) caused by eccentric exercise are generally considered to represent damage. By contrast our recent immunohistochemical studies suggested that the alterations reflect myofibrillar remodeling (Yu and Thornell 2002; Yu et al. 2003). In the present study the same human muscle biopsies were further analyzed with transmission electron microscopy and immunoelectron microscopy. We show that the ultrastructural hallmarks of DOMS, Z-disc streaming, Z-disc smearing, and Z-disc disruption were present in the biopsies and were significantly more frequent in biopsies taken 2–3 days and 7–8 days after exercise than in those from controls and 1 h after exercise. Four main types of changes were observed: amorphous widened Z-discs, amorphous sarcomeres, double Z-discs, and supernumerary sarcomeres. We confirm by immunoelectron microscopy that the main Z-disc protein alpha-actinin is not present in Z-disc alterations or in the links of electron-dense material between Z-discs in longitudinal register. These alterations were related to an increase of F-actin and desmin, where F-actin was present within the strands of amorphous material. Desmin, on the other hand, was seen in less dense regions of the alterations. Our results strongly support that the myofibrillar and cytoskeletal alterations, considered to be the hallmarks of DOMS, reflect an adaptive remodeling of the myofibrils.