Studies on the role of oxytocin in late pregnancy in the pregnant rhesus monkey: plasma concentrations of oxytocin in the maternal circulation throughout the 24-h day and the effect of the synthetic oxytocin antagonist [1-beta-Mpa(beta-(CH2)5)1,(Me(Tyr2, Orn8] oxytocin on spontaneous nocturnal myometrial contractions

Previous observations have demonstrated that under several different circumstances the pregnant rhesus monkey myometrium shows a spontaneous shift in activity from contractures to contractions around the beginning of the hours of darkness. Preliminary studies were conducted to demonstrate that the competitive oxytocin antagonist ([1-beta-Mpa(beta-(CH2)5)1,) Me)Tyr2, Orn8] oxytocin was effective in vivo in inhibiting oxytocin induced contraction type myometrial activity in the pregnant rhesus monkey in the last third of gestation. Four pregnant and one fetectomized rhesus monkey (98-141 days gestation) received one intra-arterial dose of oxytocin antagonist to study its ability to inhibit myometrial contractions occurring spontaneously around the onset of prevailing nighttime. In three pregnant monkeys (105-121 days gestation) maternal arterial plasma oxytocin levels were measured at 4-h intervals for a period of 48 h. Maternal plasma oxytocin concentration was maximal during the early hours of darkness and demonstrated a significant 24-h rhythm. From the combined results of both experiments it may be concluded that circulating oxytocin and/or a change in one of the many potential regulatory sites for oxytocin function plays a role in the switch from contractures to contractions that occurs around the beginning of the hours of darkness.     

Synchronization of estrus in early diestral dairy heifers with Prostaglandin F(2)alpha and estradiol benzoate

Following observation of estrus, 134 Holstein heifers were given injections of Prostaglandin F(2)alpha (PGF(2)alpha) between Days 5 and 10 of their cycle (estrus = Day 0). They were then randomly assigned to either a group receiving 400 mug of estradiol benzoate (E(2)B) 40 h or maintained as controls. Heifers observed in estrus within 120 h of PGF(2)alpha administration were inseminated (approximately 12 h after initial observation of estrus). Blood samples for progesterone determination were drawn from the coccygeal vein on Days 15 and 21 after insemination. Pregnancy was confirmed by palpation per rectum between Days 5.0 and 60 post insemination. When control and treated heifers were compared it was found that a higher percentage of heifers treated with E(2)B exhibited estrus after PGF(2)alpha, but there had been no effect on subsequent progesterone concentrations or pregnancy rates.     

Localisation of immunoreactive kininogen and tissue kallikrein in the human nephron

Summary The cellular localisation of kininogen and its relationships with tissue kallikrein containing cells was studied in the human kidney by the peroxidase-antiperoxidase method using antisera to human LMW kininogen and to human tissue kallikrein. Immunoreactive kininogen was localised in the principal cells of collecting ducts. Immunoreactive tissue kallikrein was detected in the connecting tubule cells segment of the nephron preceeding the cortical collecting ducts. The co-existence of tissue kallikrein and kininogen in the same transitional tubule, but in different cells, was established by the use of serial sections and double immunostaining. This anatomical relationship is in accordance with known studies that describe intermingling of principal cells and connecting tubule cells where connecting tubules merge into cortical collecting ducts in the human nephron. the close relationship between cells that contain tissue kallikrein and its substrate, kininogen, suggests that kinins could be generated in the lumen of distal cortical segments of the human nephron.     

Satiety, hunger and regional brain content of cholecystokinin/gastrin and met-enkephalin immunoreactivity in sheep

Cholecystokinin (CCK) and met-enkephalin (MEK) related peptides have been shown to alter feeding behavior subsequent to their injection into the peripheral circulation or directly into the brains of several species. To evaluate the potential role of endogenous brain pools of these peptides in feeding, groups of sheep were sacrificed either immediately following a meal (satiated) or after various intervals of food deprivation (hungry). Content of CCK-gastrin immunoreactivity in the anterior hypothalami of satiated sheep was elevated compared to 2, 4, or 24 hours of food deprivation. Content of MEK increased progressively with longer intervals of fasting (4 and 24 hours) in the amygdala and basomedial hypothalamus, whereas olfactory bulb content decreased with a similar time course. The results support a potential role for anterior hypothalamic CCK/gastrin in behaviors of satiety, whereas MEK neurons of limbic/rhinencephalic regions appear to form part of a separate circuit gradually activated by increasing hunger. Results are discussed in terms of potential target regions of the peptides, as well as the regional levels and feeding response of sheep as compared to available data from other species.     

Role of tracheal and bronchial circulation in respiratory heat exchange

Due to their anatomic configuration, the vessels supplying the central airways may be ideally suited for regulation of respiratory heat loss. We have measured blood flow to the trachea, bronchi, and lung parenchyma in 10 anesthetized supine open-chest dogs. They were hyperventilated (frequency, 40; tidal volume 30-35 ml/kg) for 30 min or 1) warm humidified air, 2) cold (-20 degrees C dry air, and 3) warm humidified air. End-tidal CO2 was kept constant by adding CO2 to the inspired ventilator line. Five minutes before the end of each period of hyperventilation, measurements of vascular pressures (pulmonary arterial, left atrial, and systemic), cardiac output (CO), arterial blood gases, and inspired, expired, and tracheal gas temperatures were made. Then, using a modification of the reference flow technique, 113Sn-, 153Gd-, and 103Ru-labeled microspheres were injected into the left atrium to make separate measurements of airway blood flow at each intervention. After the last measurements had been made, the dogs were killed and the lungs, including the trachea, were excised. Blood flow to the trachea, bronchi, and lung parenchyma was calculated. Results showed that there was no change in parenchymal blood flow, but there was an increase in tracheal and bronchial blood flow in all dogs (P less than 0.01) from 4.48 +/- 0.69 ml/min (0.22 +/- 0.01% CO) during warm air hyperventilation to 7.06 +/- 0.97 ml/min (0.37 +/- 0.05% CO) during cold air hyperventilation.     

Mapping in the mouse of the region homologous to the rat growth and reproduction complex (grc)

Offprint requests: J. Klein.     

Specific DNA probes for the identification of the fish pathogen,Renibacterium salmoninarum

To obtain specific DNA probes for the identification of the fish pathogen, Renibacterium salmoninarum, a discriminatory recombinant DNA library was constructed using selective fragments of the bacterial genome. Three renibacterial clones, pMAM29, pMAM46 and pMAM77, containing 149, 73, and 154 bp respectively, were isolated and characterized. The specificity of the probes was confirmed by dot-blot and Southern hybridization analyses. Bacterial hybridization experiments revealed that pMAM29 discriminates the R. salmoninarum genome from that of other fish pathogens such as Aeromonas salmonicida, Yersinia ruckeri, Flexibacter columnaris, Lactobacillus piscicola, Vibrio ordalii, Vibrio anguillarum and Aeromonas hydrophila. Thus, this probe may provide a new means to diagnose bacterial kidney disease in asymptomatic fish and ova.The authors are with the instituto de Bioquímica, Universidad Austral de Chile, P.O. Box 567, Valdivia, Chile