Pancreatic exocrine responses to parasympathetic stimulation in anaesthetized pigs.

Pancreatic exocrine responses to stimulation of the peripheral ends of the vagus nerves intermittently have been investigated in anaesthetized pigs and compared with the effects of continuous stimulation at corresponding frequencies. At relatively low frequencies < or =20 Hz in bursts or 2 Hz continuously) both the flow of pancreatic juice and the output of protein therein were potentiated by stimulating in bursts. Thus stimulation at 20 Hz in bursts produced a significantly greater flow of pancreatic juice than stimulation at 2 Hz continuously (10.9+/-0.9 compared to 4.8+/-0.7 microl min(-1) (g gland)-1 , respectively; P<0.01). Likewise the output of protein during intermittent stimulation at 20 Hz (144+/-23 microg min(-1) (g gland)-1) far exceeded that produced during continuous stimulation at 2 Hz (49+/-9 microg min(-1) (g gland)-1; P<0.01). Both differences were abolished by atropine (0.5 mg kg(-1) i.v.), which augmented the flow during continuous stimulation (to 8.7 +/- 1.5 microl min(-1) (g gland)-1; P<0.05 at 2 Hz) and substantially reduced the output of protein during intermittent stimulation (to 27+/-7 ng min(-1) (g gland)-1; P<0.01 at 20 Hz in bursts). These results show that a variety of pancreatic exocrine responses can be enhanced by stimulating the parasympathetic innervation in bursts. They are also consistent with the contention that the secretion of protein from the gland, in response to parasympathetic stimulation, is dependent mainly on activation of muscarinic receptors. They confirm that the flow of pancreatic juice is due mainly to the release of VIP and show that, in the absence of atropine, this is restricted by muscarinic inhibition which may be presynaptic as elsewhere.

The recovery of populations of dogwhelks suffering from imposex in the Firth of Forth 1987-1997/98.

The impact of tributyltin (TBT) contamination on dogwhelk (Nucella lapillus) populations was assessed at 33 sites in the Firth of Forth, UK, during spring 1997 and summer 1998. The sex ratio of the animals; the ratio of juveniles to adults; the degree of imposex, as determined by the relative penis size index (RPSI); and the total tin concentration in a sample of dogwhelk tissue were used as measurements of TBT impact on dogwhelk populations. These data were compared with data from a similar survey carried out at the same sites in the Firth of Forth in 1987 (Bailey, S.K., Davies, I.M., 1988. Tributyltin contamination in the Firth of Forth (1975-1987). Science of the Total Environment 76, 185-192.) before restrictions were introduced on the use of TBT. The results demonstrate a general recovery in dogwhelk populations from the impact of TBT at the majority of the sites studied, although at six of the sites, the RPSI value remains high enough to suggest breeding problems in the population. It is suggested that large vessels are responsible for localised cases of imposex within the Firth of Forth.

Immunization has no effect on arousal from sleep in the newborn infant.

OBJECTIVE: To investigate arousal from sleep in infants before and after triple antigen immunization (DTP). METHODOLOGY: Arousal thresholds were determined in both active sleep (AS) and quiet sleep (QS) the day before and the day following the first DTP immunisation in 14 infants. Arousal was induced using a pulsatile puff of air delivered alternately to the nostrils of the infant. RESULTS: Arousal threshold was significantly higher in QS compared to AS in both studies (P < 0.001). Mean arousal threshold in the pre immunization study was not different from that in the post immunization study in either sleep state. Core temperature and heart rate measured at the time of stimulus delivery were both significantly elevated in the post immunisation study (P < 0.001). Sleep duration and number of awakenings from sleep were unaffected by immunization. CONCLUSION: The first triple antigen immunisation has no effect on arousal from sleep in either AS or QS in this group of infants.

Dynamic changes in arousal threshold during sleep in the human infant.

Failure to arouse from sleep is a possible mechanism leading to sudden infant death. Using a controlled pulsatile air jet applied alternately to the nostrils we have made multiple measures of arousal threshold both between and within sleep states. Infants (n = 22) born at term were studied at 2-3 wk postterm (mean age 13 d, range 9-17 d, study 1) and again at 2-3 mo postterm (mean age 78 d, range 56-98 d, study 2). Arousal threshold (stimulus driving pressure, cm H2O) was determined in both active sleep (AS) and quiet sleep (QS). At both ages arousal threshold in QS was significantly higher (251 +/- 24 and 298 +/- 35) than in AS (163 +/- 19 and 144 +/- 29) (p < 0.001). In a morning sleep period, the first and second QS epochs were compared in each baby. In both study 1 and study 2, respectively, arousal thresholds were significantly higher in the second QS epoch (270 +/- 34 and 497 +/- 100) than in the first QS epoch (198 +/- 29 and 252 +/- 69) (p < 0.05 and p < 0.02). There was a significant correlation in individual infants between arousal thresholds in the two states at both ages (p < 0.005 and p < 0.007, respectively). Regression analysis showed no correlation between the length of time the infant had been in a particular sleep state and the arousal threshold in either state in study 1 or in AS in study 2; however, arousal threshold increased significantly (p < 0.01) with time in QS in study 2. This study has expanded on previous findings that arousability is sleep state-dependent by demonstrating that arousability in QS is also altered by the length of time that the infant has been asleep.

A method of measuring the oviposition rate of the sheep blowfly, Lucilia cuprina under field conditions.

A simple technique, which allows sheep to be rendered temporarily susceptible to fly attack, is described and used to examine oviposition rates of Lucilia cuprina under field conditions. Oviposition rates are shown to be related to both fly activity and fly density. The question of Hobson's 'live sheep factor' in attracting L. cuprina to sheep is re-considered.

Alternative birthing center: experience in a teaching obstetric service.

The Illinois Masonic Medical Center's (IMMC) experience with an Alternative Birthing Center (ABC), established as an integral part of the conventional obstetric suite, has proved to be a safe and efficacious method of providing a true alternative to high technology obstetric care to those carefully screened, low-risk patients who elect this form of childbirth experience. However, the high transfer rate (23.8%) and substantial cesarean birth rate (9.17%) in this low-risk group of patients do demonstrate the necessity for the immediate availability of conventional and high technology obstetric facilities, as well. The low incidence of neonatal morbidity demonstrates that the ABC is a safe environment for the neonate. Acceptance and utilization of the ABC by consumers and professionals is rapidly increasing as it is demonstrated to be a safe alternative to birth in a conventional delivery suite or home delivery.