title: An investigation of the distribution of gastrin-like activity, and its nature, in the gastrointestinal tract of the sheep

authors: Jury, Denis R.

abstract: Using a modification of the extraction procedure of Gregory and Tracy (1964), and a perfused rat stomach bioassay, gastrin-like activity has been located in the ovine rumen, reticulum, omasum, abomasal body, antrum, duodenum and caecum. The antrum showed the highest concentration of gastrin-like activity, but substantial concentrations were found in the rumen, reticulum, omasum and caecum and proximal duodenum declining progressively with distance from the pylorus. A lesser concentration occurred in the abomasal body. Consideration of the relative total content of gastrin-like activity showed that the amount of extra-antral activity was substantial. 
The active principle was unlikely to have been cholecystokinin as the extracts had isoelectric points of a more acidic nature than that of cholecystokinin. Similarly, bioassay using an isolated guinea-pig ileum showed histamine to be absent from the extracts.
Extraction of rumenal, reticular, omasal, abomasal body and antral mucosa and muscle separately showed that the gastrin-like activity resided almost completely in the mucosa.
An investigation of the gastrin-like activity of air dried and freeze dried extracts showed that the freeze dried extracts were approximately 50% more active than the air dried extracts. Bioassay of a freeze dried antral extract over a twenty four week period showed that the activity was maintained for the initial six weeks, and that 80% of the activity was then lost over the following eighteen weeks.
Studies using columns of Sephadex have shown that extracts from all regions of the ovine gastro-intestinal tract investigated were similar and consisted of several components of differing molecular weight. By a comparison of their respective molecular weights, to those reported for components separated from extracts of non-ruminant origin, it seems likely that components corresponding to MG, HLG, BG, BBG and component I were present in varying amounts. 
The response to infusions of gastrin extract in fed and fasted sheep were different. In fasted sheep infusions of extract, after a relatively long latent period, caused a small, but prolonged increase in acid secretion. In contrast pentagastrin caused an immediate and pronounced response. In fed sheep the responses were variable. 
Experiments on a single dolphin (Delphinus delpis) have shown there to be gastrin-like activity present in the forestomach, mainstomach, pyloric stomach, duodenal ampulla and intestine of this mammal. 
The distribution of gastrin-like activity reported in the present work has been compared to previous reports concerning the distribution of gastrin activity in animals with a more simple stomach, and the possible function of gastrin in the ruminant has been discussed.

text: An investigation of the distribution of gastrin-like activity, and its nature, in the gastrointestinal tract of the sheep Using a modification of the extraction procedure of Gregory and Tracy (1964), and a perfused rat stomach bioassay, gastrin-like activity has been located in the ovine rumen, reticulum, omasum, abomasal body, antrum, duodenum and caecum. The antrum showed the highest concentration of gastrin-like activity, but substantial concentrations were found in the rumen, reticulum, omasum and caecum and proximal duodenum declining progressively with distance from the pylorus. A lesser concentration occurred in the abomasal body. Consideration of the relative total content of gastrin-like activity showed that the amount of extra-antral activity was substantial. 
The active principle was unlikely to have been cholecystokinin as the extracts had isoelectric points of a more acidic nature than that of cholecystokinin. Similarly, bioassay using an isolated guinea-pig ileum showed histamine to be absent from the extracts.
Extraction of rumenal, reticular, omasal, abomasal body and antral mucosa and muscle separately showed that the gastrin-like activity resided almost completely in the mucosa.
An investigation of the gastrin-like activity of air dried and freeze dried extracts showed that the freeze dried extracts were approximately 50% more active than the air dried extracts. Bioassay of a freeze dried antral extract over a twenty four week period showed that the activity was maintained for the initial six weeks, and that 80% of the activity was then lost over the following eighteen weeks.
Studies using columns of Sephadex have shown that extracts from all regions of the ovine gastro-intestinal tract investigated were similar and consisted of several components of differing molecular weight. By a comparison of their respective molecular weights, to those reported for components separated from extracts of non-ruminant origin, it seems likely that components corresponding to MG, HLG, BG, BBG and component I were present in varying amounts. 
The response to infusions of gastrin extract in fed and fasted sheep were different. In fasted sheep infusions of extract, after a relatively long latent period, caused a small, but prolonged increase in acid secretion. In contrast pentagastrin caused an immediate and pronounced response. In fed sheep the responses were variable. 
Experiments on a single dolphin (Delphinus delpis) have shown there to be gastrin-like activity present in the forestomach, mainstomach, pyloric stomach, duodenal ampulla and intestine of this mammal. 
The distribution of gastrin-like activity reported in the present work has been compared to previous reports concerning the distribution of gastrin activity in animals with a more simple stomach, and the possible function of gastrin in the ruminant has been discussed.

year: 1978

title: Comparison of changes in electroencephalographic measures during induction of general anaesthesia: influence of the gamma frequency band and electromyogram signal

authors: Sleigh, James W.

subjects: monitoring

abstract: Recent research has shown that high-frequency, gamma-band electroencephalographic (EEG) oscillations (40–60 Hz) may be an important marker of the conscious state. We compared the ability of the bispectral index (BIS) to distinguish the awake and anaesthetized states during the induction of general anaesthesia with: (i) components of the BIS (BetaRatio, SynchFastSlow); (ii) a new EEG variable—the median frequency of the first time derivative of the EEG signal (SE50d); and (iii) the SE50d derived from an EEG signal that has had the frequencies above 30 Hz removed (SE50d30Hz). Two groups of subjects were studied: (i) nine volunteers undergoing a short propofol infusion until loss of response to verbal command, and (ii) 84 patients undergoing routine anaesthesia for a variety of surgical procedures. In the volunteer group, the changes in the BetaRatio and SE50d were comparable with changes in the BIS. The changes in the SE50d30Hz were less consistent. In the patient group, the BIS components were equivalent to the BIS in separating the awake from the surgically anaesthetized states (area under receiver operating curve: BIS 0.95, SE50d 0.95, BetaRatio 0.96). Using the submental electromyogram (EMG) signal to estimate the frontalis EMG (30–47 Hz) signal, the changes in EMG signal were, on average, about one-tenth the magnitude of the EEG. We conclude that: (i) there exist simpler derived EEG variables that are similar in accuracy to the BIS; (ii) it is important to avoid filtering out the EEG frequencies above 30 Hz; and (iii) in most patients the confounding effects of the frontalis EMG on the EEG are minimal.

text: Comparison of changes in electroencephalographic measures during induction of general anaesthesia: influence of the gamma frequency band and electromyogram signal Recent research has shown that high-frequency, gamma-band electroencephalographic (EEG) oscillations (40–60 Hz) may be an important marker of the conscious state. We compared the ability of the bispectral index (BIS) to distinguish the awake and anaesthetized states during the induction of general anaesthesia with: (i) components of the BIS (BetaRatio, SynchFastSlow); (ii) a new EEG variable—the median frequency of the first time derivative of the EEG signal (SE50d); and (iii) the SE50d derived from an EEG signal that has had the frequencies above 30 Hz removed (SE50d30Hz). Two groups of subjects were studied: (i) nine volunteers undergoing a short propofol infusion until loss of response to verbal command, and (ii) 84 patients undergoing routine anaesthesia for a variety of surgical procedures. In the volunteer group, the changes in the BetaRatio and SE50d were comparable with changes in the BIS. The changes in the SE50d30Hz were less consistent. In the patient group, the BIS components were equivalent to the BIS in separating the awake from the surgically anaesthetized states (area under receiver operating curve: BIS 0.95, SE50d 0.95, BetaRatio 0.96). Using the submental electromyogram (EMG) signal to estimate the frontalis EMG (30–47 Hz) signal, the changes in EMG signal were, on average, about one-tenth the magnitude of the EEG. We conclude that: (i) there exist simpler derived EEG variables that are similar in accuracy to the BIS; (ii) it is important to avoid filtering out the EEG frequencies above 30 Hz; and (iii) in most patients the confounding effects of the frontalis EMG on the EEG are minimal.

year: 2001

title: Māori leaders wellbeing: A self-determination perspective

authors: Roche, Maree A.

subjects: Positive psychology

abstract: This research draws on interviews with 18 Māori leaders from various leadership positions within business, community, political and marae organisations, to garner an understanding of how their leadership roles interact with their own well-being. Analysis of interviews revealed that crosscultural developments in self-determination theory could be gained by incorporating Māori tikanga and values into a model of well-being for Māori leaders. Largely, the principles of tino rangatiratanga (autonomy and self-determination), mana (respect and influence), whānau (extended family), whakapapa (shared history) and whanaungatanga (kin relations, consultation and engagement), were united into a model of leader well-being. This ensured that mātauranga Māori (Māori knowledge) informed our model of Māori leader well-being, while also drawing on the burgeoning Western research in the area of well-being, specifically self-determination theory. Overall, we find that similarities exist with self-determination theory and Māori tikanga and values. However, in contrast to self-determination theory, autonomy and competence are developed within relationships, which means that ‘others’ underpin Māori leaders’ well-being. From this perspective, we present a view of the psychological and well-being resources that Māori leaders draw on to guide them through complex times.

text: Māori leaders wellbeing: A self-determination perspective This research draws on interviews with 18 Māori leaders from various leadership positions within business, community, political and marae organisations, to garner an understanding of how their leadership roles interact with their own well-being. Analysis of interviews revealed that crosscultural developments in self-determination theory could be gained by incorporating Māori tikanga and values into a model of well-being for Māori leaders. Largely, the principles of tino rangatiratanga (autonomy and self-determination), mana (respect and influence), whānau (extended family), whakapapa (shared history) and whanaungatanga (kin relations, consultation and engagement), were united into a model of leader well-being. This ensured that mātauranga Māori (Māori knowledge) informed our model of Māori leader well-being, while also drawing on the burgeoning Western research in the area of well-being, specifically self-determination theory. Overall, we find that similarities exist with self-determination theory and Māori tikanga and values. However, in contrast to self-determination theory, autonomy and competence are developed within relationships, which means that ‘others’ underpin Māori leaders’ well-being. From this perspective, we present a view of the psychological and well-being resources that Māori leaders draw on to guide them through complex times.

year: 2015