Showing papers by "Flinders University published in 1990"

Rapid Isolation of Metabolically Active Mitochondria from Rat Brain and Subregions Using Percoll Density Gradient Centrifugation

Abstract: Two procedures are described for isolating free (nonsynaptosomal) mitochondria from rat brain. Both procedures employ a discontinuous Percoll gradient and yield well coupled mitochondria which exhibit high rates of respiratory activity and contain little residual contamination by synaptosomes or myelin. The procedures are considerably more rapid than methods described previously for the isolation of brain mitochondria and do not require an ultracentrifuge or swing-out rotor. The first method separates mitochondria by gradient centrifugation from a P2 (crude mitochondrial) fraction and is likely to be widely applicable for studies in which at least 500 mg of tissue are available as starting material. In the second method, the unfractionated homogenate is subjected directly to gradient centrifugation. This method requires the preparation of more gradients (per gram of tissue) than the first method and yields a subcellular fraction with slightly more synaptosomal contamination. However, this second procedure is more rapid, requires less manipulation of the tissue, and is suitable for obtaining mitochondria with well preserved metabolic characteristics from subregions of single rat brains.

Metabolism of 2-Acetylaminofluorene and Benzo(a)pyrene and Activation of Food-derived Heterocyclic Amine Mutagens by Human Cytochromes P-450

Abstract: The human P-450 CYP1A1 gene and a P450IA2 complementary DNA have been expressed in Cos-1 cells and the expressed proteins were assayed for their capacity to metabolize the carcinogens 2-acetylaminofluorene (AAF), benzo( a )pyrene, 2-amino-3-methylimidazo[4,5- f ]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5- f ]quinoline, 2-amino-3,8-dimethylimidazo[4,5- f ]quinoxaline, 2-amino-3,4,8-trimethylimidazo[4,5- f ]quinoxaline, 2-amino-1-methyl-6-phenylimidazo[4,5- b ]pyridine (PhIP) was determined. The expressed human P450IA1 and P450IA2 proteins, when run on a 7.5% sodium dodecyl sulfate-polyacrylamide gel, migrated with different mobilities, with the former displaying the lower molecular weight. In human liver microsomes from 18 subjects, only a protein band corresponding to P450IA2 was detectable. Cos-1 cell-expressed P450IA1 and P450IA2 were capable of N -hydroxylating AAF and these activities were inhibited by α-naphthoflavone. In human liver microsomes, a correlation of r = 0.76 ( P n = 18) was obtained between AAF N -hydroxylase activity and P450IA2 content. AAF N -hydroxylase activity of human liver microsomes was also strongly inhibited by α-naphthoflavone. Except in the case of PhIP, where both proteins exhibited similar activities, P450IA2 was at least an order of magnitude more efficient than P450IA1 in activating IQ, 2-amino-3,4-dimethylimidazo[4,5- f ]quinoline, 2-amino-3,8-dimethylimidazo[4,5- f ]quinoxaline, and 2-amino-3,4,8-trimethylimidazo[4,5- f ]quinoxaline to mutagens as measured in the Ames test. Statistically significant correlations were obtained between IQ activation and P450IA2 content ( r = 0.75, r 2 = 0.56) and PhIP activation and P450IA2 content ( r = 0.71, r 2 = 0.5) in human liver microsomes. The activation of both IQ and PhIP by expressed proteins and human liver microsomes was strongly inhibited by α-naphthoflavone. The above data suggest a major role for P450IA2 in activation ( N -hydroxylation) of aromatic amides and amines in human liver. When benzo( a )pyrene hydroxylase activity was determined, only Cos-1 cell-expressed P450IA1 exhibited appreciable activity. While α-naphthoflavone inhibited Cos-1 cell-expressed P450IA1 benzo( a )pyrene hydroxylase activity, it caused a marked stimulation of this activity in human liver microsomes, which lack P450IA1 protein. The lack of a role for P450IA proteins in benzo( a )pyrene metabolism is further supported by the poor correlation ( r = 0.43, P > 0.05) between this activity and P450IA2 content of human liver microsomes. However, when P450IIIA3 content of the above human liver microsomes was determined by using the Western blot technique and correlated with benzo( a )pyrene metabolism, an r value of 0.70 ( P a )pyrene metabolism.

Performance measures of 16- to 86-year-old males and females on the auditory verbal learning test

Abstract: This study reports Auditory Verbal Learning Test (AVLT) data for 153 adults in age groups spanning seven decades, with approximately equal numbers of males and females and matched for intelligence, education, and occupation. Overall performance deteriorated with increased age, females performing better than males. Older subjects recalled fewer words, were more susceptible to information overload during input, showed diminished retrieval efficiency, and had a decline in memory for the source of items. In contrast, rate of learning, forgetting over 20-min, monitoring of recall, and interference effects remained stable across the age range.

Accounting History: Definition and Relevance

Abstract: This paper defines and relates contemporary applications of accounting history and is intended to assist scholars who do not specialize in historical study. A definitional distinction is drawn between history as a social science, with an emphasis on interpretation, criticism, and method, and history as a descriptive narrative form. Arguments are presented for the relevance of published accounting history studies to accounting pedagogy, policy and practice. The inherent limitations of historical inquiry are also explored. An appendix provides information on accounting history organizations, publications, and activities worldwide. A related paper which develops an accounting historiography will appear in a later issue of this journal.

An Accounting Historiography: Subject Matter and Methodology

Abstract: This paper continues to study issues developed in a preceding manuscript which provided a definitional context for accounting history, its uses and limitations as a method of inquiry related to educational endeavours, standard setting and practice. In this study two aspects of the development of the history of accounting, subject matter and methodology, are extensively explored within the context of a definition of historiography. A set of outline tables is provided to assist researchers considering the topic areas as well as the process of historical inquiry, especially those scholars who do not specialise in historical study. As in the previous paper, an extensive bibliography is provided.

Calbindin neurons of the guinea-pig small intestine: quantitative analysis of their numbers and projections.

Abstract: The distribution of nerve cells with immunoreactivity for the calcium-binding protein, calbindin, has been studied in the small intestine of the guinea-pig, and the projections of these neurons have been analysed by tracing their processes and by examining the consequences of nerve lesions. The immunoreactive neurons were numerous in the myenteric ganglia; there were 3500±100 reactive nerve cells per cm2 of undistended intestine, which is 30% of all nerve cells. In contrast, reactive nerve cells were extremely rare in submucous ganglia. The myenteric nerve cells were oval in outline and gave rise to several long processes; this morphology corresponds to Dogiel's type-II classification. Processes from the cell bodies were traced through the circular muscle in perforating nerve fibre bundles. Other processes ran circumferentially in the myenteric plexus. Removal of the myenteric plexus, allowing time for subsequent fibre degeneration, showed that reactive nerve fibres in the submucous ganglia and mucosa came from the myenteric cell bodies. Operations to sever longitudinal or circumferential pathways in the myenteric plexus indicated that most reactive nerve terminals in myenteric ganglia arise from myenteric cell bodies whose processes run circumferentially for 1.5 mm, on average. It is deduced that the calbindin-reactive neurons are multipolar sensory neurons, with the sensitive processes in the mucosa and with other processes innervating neurons of the myenteric plexus.

The Development of Gender Differences in Body‐Size Dissatisfaction

Abstract: This study aimed to replicate with an Australian sample Fallon and Rozin's (1985) finding of gender differences in body dissatisfaction, and to further investigate the developmental origins of such dissatisfaction. There were three age groups of subjects: adult undergraduates, adolescents aged 15–16 years, and children aged 9–10 years. All subjects were presented with a set of nine age-relevant silhouette drawings ranging from very thin to very heavy. Adult women rated their current figure as significantly larger than their ideal and attractive figure, whereas there were no differences in rating for men. In contrast to the finding of Cohn et al., (1987), this pattern was replicated in the adolescent group, such that girls, but not boys, showed substantial body dissatisfaction. In the youngest age group, all the children rated their current figures as larger than their ideal. It was concluded that both adolescent and adult women expressed body dissatisfaction and were subjected to pressures toward...

Distension-evoked ascending and descending reflexes in the circular muscle of guinea-pig ileum: an intracellular study.

Abstract: Reflex responses evoked by distension of the guinea-pig small intestine were recorded from the circular muscle with intracellular microelectrodes. For this purpose a mechanically stable preparation that allowed the intestinal wall to be distended within 9 mm of the recording site was developed. A segment of intestine was opened along the mesenteric border and pinned mucosa uppermost over a balloon set in the base of an organ bath, so that inflation of the balloon could distend the intestinal wall without simultaneously pushing against the mucosa. Compound excitatory junction potentials (EJPs) and compound inhibitory junction potentials (IJPs) were recorded at sites up to 40 mm oral and anal to the distending stimulus, respectively. The compound EJPs recorded orally had amplitudes of up to 24 mV and declined to baseline during distensions that exceeded 10-15 s. Distensions at intervals of less than 20 s evoked successively smaller oral compound EJPs; after four distensions in 30 the amplitude of the compound EJP had fallen to less than 10%. The amplitude of the oral compound EJP was reduced by hyoscine (1 microM), but the extent of the reduction depended on the degree of distension; responses to mild stimuli were blocked, whereas those to strong stimuli were only slightly reduced. The amplitude of the hyoscine-resistant component of the compound EJP was markedly reduced by antagonists of substance P receptors in the muscle. In the presence of muscarinic and substance P receptor antagonists, a transient compound IJP could be detected on the oral side of the stimulus. The compound IJPs recorded anal to the distension had amplitudes up to 22 mV but the potential returned to baseline during prolonged distension. In the presence of hyoscine (1 microM) some inhibitory activity continued throughout prolonged stimuli. Compound IJP amplitudes were not significantly reduced by repeated distensions separated by more than 6 s. At anal sites a transient depolarization (off-response) was recorded immediately following the termination of a distension in some preparations. The off-response was unaffected by hyoscine and was more readily observed after the further addition of substance P antagonists. The compound IJPs were almost completely blocked by apamin (0.2 microM). The compound EJPs and IJPs recorded orally were blocked by hexamethonium (100 microM), but the amplitudes of compound IJPs recorded anally were significantly reduced by hexamethonium (100-200 microM) only at recording sites greater than 15 mm from the centre of the balloon. The off-response was reduced by hexamethonium at all sites.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of exercise intensity and duration on postexercise metabolism

Abstract: Data are reported on the net recovery O2 consumption (VO2) for nine male subjects (mean age 21.9 yr, VO2max 63.0 ml.kg-1.min-1, body fat 10.6%) used in a 3 (independent variables: intensities of 30, 50, and 70% VO2max) x 3 (independent variables: durations of 20, 50, and 80 min) repeated measures design (P less than or equal to 0.05). The 8-h mean excess postexercise O2 consumptions (EPOCs) for the 20-, 50-, and 80-min bouts, respectively, were 1.01, 1.43, and 1.04 liters at 30% VO2max (6.8 km/h); 3.14, 5.19, and 6.10 liters at 50% VO2max (9.5 km/h); and 5.68, 10.04, and 14.59 liters at 70% VO2max (13.4 km/h). The mean net total O2 costs (NTOC = net exercise VO2 + EPOC) for the 20-, 50-, and 80-min bouts, respectively, were 20.48, 53.20, and 84.23 liters at 30% VO2max; 38.95, 100.46, and 160.59 liters at 50% VO2max; and 58.30, 147.48, and 237.17 liters at 70% VO2max. The nine EPOCs ranged only from 1.0 to 8.9% of the NTOC (mean 4.8%) of the exercise. These data, therefore, indicate that in well-trained subjects the 8-h EPOC per se comprises a very small percentage of the NTOC of exercise.

The relative effects of unemployment and quality of employment on the affect, work values and personal control of adolescents

Abstract: This study examined the relative effects of unemployment and quality of employment on the affective states, personal control and work values of school-leavers. Initially, students were surveyed at school and then reassessed two years later when they were either unemployed, employed or continuing their education. Those in employment were categorized as being in good or poor employment on the basis of the degree to which their jobs allowed them to utilize their skills and education. When school-leavers who obtained good quality employment were compared with those who were unemployed, they had lower depressive affect, higher life-satisfaction, higher internal control and higher personal competence. However, there was little difference on these variables between the unemployed and the poor employment groups. Both of these groups, when compared with students and those in good employment, had higher depressive affect, lower work values and lower personal control. All of these results were confirmed when analyses controlled for testing effects and initial differences on the dependent variables. These results show that the relative effects of employment and unemployment upon adolescents depend on the quality of experienced employment.

Sleep-onset insomniacs have delayed temperature rhythms.

Abstract: It was predicted from free running and ultradian cycle studies that sleep-onset insomniacs would have endogenous circadian rhythms that were phase delayed compared to good sleepers. Thirteen sleep-onset insomniacs and nine good sleepers were selected to differ only in their sleep-onset latencies as confirmed by polysomnography. their rectal temperatures were measured over a 26-h constant routine and analyzed with best-fit Fourier curves including 24-h fundamental and 12-h harmonic components. The temperature rhythm markers of the insomniacs' rhythms were approximately 2.5 h later than the respective phases of the good sleepers. The usual bedtimes of the insomniacs fell within the "wake maintenance zone" of their delayed temperature rhythm. The good sleepers had typical bedtimes several hours after their "wake maintenance zone" and closer to their body temperature minimum. It was suggested that manipulations to phase advance the insomniacs' rhythms would reduce their sleep-onset latencies. It was also predicted that early morning insomnia results from phase advanced circadian rhythms and that sleep maintenance insomnia results from an abnormal phase relationship between the 24-h temperature rhythm and 12-h sleep-alert rhythm.

Heritability of locomotor performance and its correlates in a natural population

Abstract: Locomotor capacities and their physiological bases are thought to be of considerable selective importance in natural populations. Within this functional complex, organismal performance traits (e.g., speed, stamina) are expected to be of more direct selective importance than their suborganismal determinants (e.g., heart size). Quantitative genetics theory predicts that traits of greater selective importance should generally have lower heritabilities at equilibrium. Contrary to these expectations, we report that organismal performance traits had the highest heritabilities in a natural population of garter snakes.

Validation of the tolbutamide metabolic ratio for population screening with use of sulfaphenazole to produce model phenotypic poor metabolizers.

Abstract: The present study has validated kinetically a convenient method to measure tolbutamide hydroxylation capacity in human beings by use of urinary metabolic ratios. The known in vivo and in vitro inhibitory properties of sulfaphenazole were used to convert control phase subjects to phenotypically “poor” metabolizers of tolbutamide. Six healthy subjects were given a single 500 mg oral dose of tolbutamide with and without sulfaphenazole, 500 mg every 12 hours. Tolbutamide, hydroxytolbutamide, and carboxytolbutamide in urine were determined by newly developed HPLC procedures. Plasma tolbutamide clearance and half-life were measured, as were the metabolic ratio (hydroxytolbutamide + carboxytolbutamide/tolbutamide) in successive 6-hour urine collections. The mean tolbutamide plasma clearance decreased from 0.196 ± 0.026 ml/min/kg without sulfaphenazole to 0.039 ± 0.009 ml/min kg with sulfaphenazole, and the mean half-life of tolbutamide increased from 7.28 ± 0.89 hours to 38.76 ± 13.30 hours. The metabolic ratio determined in the 6 to 12 hour urine collection period decreased from 794.0 ± 86.6 to 126.0 ± 79.3, and this collection period also gave the best separation of subjects between phases. There was a good correlation between tolbutamide plasma clearance and metabolic ratio (rs = 0.853, p < 0.01, n = 12) and between the percentage decrease in plasma tolbutamide clearance and the percentage decrease in metabolic ratio (r = 0.932, p < 0.01, n = 6). The tolbutamide urinary metabolic ratio therefore effectively distinguishes tolbutamide hydroxylase activity in “normal” subjects and in those converted to model phenotypically “poor” metabolizers by sulfaphenazole. Clinical Pharmacology and Therapeutics (1990) 47, 403–411; doi:10.1038/clpt.1990.46

The effect of exercise intensity and duration on the oxygen deficit and excess post-exercise oxygen consumption.

Abstract: Nine males with mean maximal oxygen consumption (\(\dot V_{O_2 \max } \)) =63.0 ml· kg−1 · min−1, SD 5.7 and mean body fat = 10.6%, SD 3.1 each completed nine counterbalanced treatments comprising 20, 50 and 80 min of treadmill exercise at 30, 50 and 70%\(\dot V_{O_2 \max } \). The OZ deficit, 8 h excess post-exercise oxygen consumption (EPOC) and EPOC:O2 deficit ratio were calculated for all subjects relative to mean values obtained from 2 control days each lasting 9.3 h. The O2 deficit, which was essentially independent of exercise duration, increased significantly (P 0.05) between the three EPOCs after walking at 30%\(\dot V_{O_2 \max } \) for 20 (1.01 l), 50 (1.43 l) and 80 min (1.041), respectively, the EPOC thereafter increased (P<0.05) with both intensity and duration such that the increments were much greater for the three 70%\(\dot V_{O_2 \max } \) workloads (EPOC: 20 min=5.68 l; 50 min=10.04 l; 80 min= 14.59 l) than for the three 50%\(\dot V_{O_2 \max } \) workload (EPOC: 20 min =3.14 l; 50 min=5.19 l; 80 min= 6.10 l). An analysis of variance indicated that exercise intensity was the major determinant of the EPOC since it explained five times more of the EPOC variance than either exercise duration or the intensity times duration interaction. The mean EPOC:O2 deficit ratio ranged from 0.8 to 4.5 and generally increased with both exercise intensity and duration. These data imply that the EPOC is more than mere repayment of the O2 deficit because metabolism is increasingly disturbed from resting levels as exercise intensity and duration increase due to other physiological factors occurring after the steady-state has been attained.

Galanin immunoreactive neurons in the human hypothalamus: colocalization with vasopressin-containing neurons.

Abstract: Galanin (GA) is a recently described neuropeptide that has been demonstrated to be widely distributed in the hypothalamus of experimental animals. So far there is no immunohistochemical description of GA in the human hypothalamus and, in particular, no studies of the colocalization of this neuropeptide with other transmitter candidates in the human hypothalamus. We have now investigated this question immunohistochemically by using human brains fixed by vascular perfusion within 24 hours of death. Nerve cell bodies and fibers stained for GA were observed throughout the hypothalamus. Major populations of GA-ir cell bodies were found in the suprachiasmatic, intermediate, supraoptic, paraventricular, arcuate, tuberomammillary, and supramammillary nuclei. Scattered positive neurons were found in the periventricular preoptic area, the posterior hypothalamic nucleus, the lateral hypothalamic area, and zona incerta. A few positive cells were located in the dorsomedial and ventromedial hypothalamic nuclei. The number of GA-ir neurons estimated from three brains was 11,100 +/- 2,400 for the intermediate nucleus, 57,800 +/- 9,100 for the supraoptic nucleus and 47,400 +/- 13,900 for the paraventricular nucleus. GA-ir fibers were widely distributed in the hypothalamus. They were more dense in the periventricular and medial hypothalamic zones, whereas the lateral tuberal nuclei and the dorsolateral part of the supraoptic nucleus contained sparse positive fibers. The mammillary complex contained almost no GA-ir fibers. In the ventromedial tuberal region, GA-ir axons formed bundles travelling down in the infundibular stem. In the median eminence the vascular plexus was wrapped by GA-ir fiber networks. The coexistence of GA with arginine vasopressin (AVP), oxytocin (OXY), and tyrosine hydroxylase (TH) was examined in the supraoptic, paraventricular, and suprachiasmatic nuclei in adjacent paraffin sections. Neurons containing both GA and AVP were very common in the supraoptic nucleus and also occurred in the paraventricular and suprachiasmatic nuclei. The supraoptic and paraventricular nuclei also contained some neurons immunoreactive for both GA and OXY. Neurons positive for GA and TH were rare. The topographic distribution of GA-ir neuronal structures in the hypothalamus and the colocalization of GA, principally with AVP and to a lesser extent with OXY, in some hypothalamic nuclei constitute anatomical evidence that this neuropeptide may be involved in the regulation of endocrine, autonomic, and behavioural homeostatic responses.

Differential cross sections for electron-impact excitation of the electronic states of N 2

Abstract: Differential cross sections for the electron-impact excitation of the first ten electronic states of ${\mathrm{N}}_{2}$ have been determined at five incident energies ranging from 15 to 50 eV. These differential cross sections were obtained for the scattering range 10\ifmmode^\circ\else\textdegree\fi{}--90\ifmmode^\circ\else\textdegree\fi{} by analyzing electron-energy-loss spectra in ${\mathrm{N}}_{2}$ at a number of fixed scattering angles within that range. The present study represents a comprehensive remeasurement of the earlier work of Cartwright and co-workers [Phys. Rev. A 16, 1013 (1977)] and was undertaken with a view to resolving certain anomalies which have been reported in the literature when the earlier cross-section set has been applied to model calculations of swarm parameters.

Physical behaviour of a large, negative or inverse estuary

Abstract: The observational behaviour of a large, negative or inverse estuary is discussed in the context of theoretical, and laboratory models of gravitationally driven circulations. The characteristics of Spencer Gulf, South Australia, in which evaporation exceeds precipitation all year round, and the spring-neap tidal cycle is greatly exaggerated, make it particularly instructive with regard to the role of turbulence in controlling the strength of the baroclinic circulation, and hence the exchange between Gulf and shelf waters. Seasonal influences, involving the reversal of the temperature gradient across the mouth, are shown to have a profound impact on this Gulf-shelf exchange. The development of strong temperature and salinity fronts which are compensatory with respect to density, removes almost all baroclinic forcing in the region and effectively blocks communication across the Gulf entrance during summer. It is apparent that the equilibrium of such systems relies on the sensitive interplay of influences primarily related to the nature of the change from estuary to shelf regime across the entrance, and the variability of turbulence in the region.

Managerial accounting early in the British Industrial Revolution: The Carron Company, a case study

Abstract: Traditional accounting histories date the advent of sophisticated cost accounting to the mid-1880s. Research in recent years, however, has provided evidence of purposeful cost management during the British Industrial Revolution. Given the advances in capital accumulation techniques, market structure development, and technology, it might have been expected that British entrepreneurs would have appreciated the advantages that effective costing could provide. This article is a case study of the Carron Company, the huge Scottish ironworks, whose cost accounting methods were notably innovative during the period for which plentiful archival records exist: 1759–1786. Carron's utilisation and practice of cost management is examined in the areas of expenditure control; responsibility and departmental cost management; overhead allocation; cost comparisons and transfers; costs for decision-making; budgets, forecasts, and standards; and inventory control. The positive findings in all these activity areas con...

Catecholamines and catecholamine-synthesizing enzymes in guinea-pig sensory ganglia

Abstract: Cranial and spinal sensory ganglia of the guinea-pig were investigated by means of histochemistry and biochemistry for the presence of catecholamines and catecholamine-synthesizing enzymes. Sensory neurons exhibiting immunoreactivity to the rate-limiting enzyme of catecholamine synthesis, tyrosine hydroxylase (TH), were detected by immunohistochemistry in lumbo-sacral dorsal root ganglia, the nodose ganglion and the petrosal/jugular ganglion complex. The carotid body was identified as a target of TH-like-immunoreactive (TH-LI) neurons by the use of combined retrograde tracing and immunohistochemistry. Double-labelling immunofluorescence revealed that most TH-LI neurons also contained somatostatin-LI, but TH-LI did not coexist with either calcitonin gene-related peptide- or substance P-LI. TH-LI neurons did not react with antibodies to other enzymes involved in catecholamine synthesis, i.e., aromatic amino acid decarboxylase (AADC), dopamine-beta-hydroxylase (D beta H), and phenylethanolamine-N-methyl-transferase (PNMT). Petrosal neurons as well as their endings in the carotid body lacked dopamine- and L-DOPA-LI. Sensory neurons did not display glyoxylic acid-induced catecholamine fluorescence. Ganglia containing TH-LI neurons were kept in short-term organ culture after crushing their roots and the exiting nerve in order to enrich intra-axonal transmitter content at the ganglionic side of the crush. However, even under these conditions, catecholamine fluorescence was not detected in axons projecting peripherally or centrally from the ganglia. Sympathetic noradrenergic nerves entered the ganglia and terminated within them. Accordingly, biochemical analyses of guinea-pig sensory ganglia revealed noradrenaline but no dopamine. In conclusion, catecholamines within guinea-pig sensory ganglia are confined to sympathetic nerves, which fulfill presently unknown functions. The TH-LI neurons themselves, however, lack any additional sign of catecholamine synthesis, and the presence of enzymatically active TH within these neurons is questionable.

Projections of substance P, vasoactive intestinal peptide and tyrosine hydroxylase immunoreactive nerve fibres in the canine intestine, with special reference to the innervation of the circular muscle.

Abstract: Antisera raised against neuron specific enolase (NSE), substance P, vasoactive intestinal peptide (VIP) and tyrosine hydroxylase (TH) were used to reveal nerve fibres in the wall of the canine small and large intestine. The circular muscle of the colon was innervated by nerve fibre bundles that ran parallel to the muscle throughout its thickness. A plexus of fibre bundles was found against the inner (submucosal) surface of the circular muscle. Fibres with substance P, VIP and TH immunoreactivity all contributed to this innervation. The circular muscle of the small intestine was distinctly separated into outer and inner layers by a dense plexus of nerve fibres, the deep muscular plexus. The outer and inner circular muscle were innervated by substance P, VIP and TH fibres. Extrinsic denervation through the severing of nerve fibres in the mesentery caused TH fibres in the intestine to degenerate, but had no detectable effect on the fibres with substance P or VIP immunoreactivity. Myectomy (the removal of the myenteric plexus from the full circumference of the intestine over a distance of 2-3 cm), performed 7-13 days before tissue was taken, resulted in an almost complete loss of substance P fibres from the circular muscle of the colon and the outer circular muscle of the small intestine. However, many fibres persisted in the deep muscular plexus of the small intestine, and most fibres remained in its inner circular muscle. The changes in distribution of VIP fibres were almost identical, except that a small proportion of reactive fibres remained in the circular muscle of the colon and the outer circular muscle of the small intestine. It is concluded that the circular muscle layers of the small intestine and colon have dual sources of intrinsic nerve supply: the myenteric ganglia supply fibres primarily to the outer part of the muscle and the submucous ganglia supply fibres to the inner muscle. The present study further demonstrated that VIP fibres ran anally in the myenteric plexus of both the small and large intestine, whereas substance P fibres ran orally in the large intestine and both orally and anally in the small intestine. The innervation of the muscularis mucosae and mucosa by substance P and VIP fibres was not affected by myectomy or extrinsic denervation, and these structures are therefore likely to be innervated by nerve cells in the submucous ganglia.

Cholera toxin B‐gold, a retrograde tracer that can be used in light and electron microscopic immunocytochemical studies

Abstract: The purpose of this study was to test whether a new retrograde tracer, the B subunit of cholera toxin conjugated to colloidal gold particles (CTB-gold), was taken up and transported by neurons in the central nervous system of the rat Retrograde transport of CTB-gold was assessed from axon terminals, from damaged nerve fibers, and from axons of passage For light microscopy, CTB-gold was visualized by silver intensification; for electron microscopy, sections were silver-intensified with or without subsequent gold toning Retrogradely transported CTB-gold was detected in neurons after survival times of 12 hours to 42 days and appeared as black punctate deposits in perikarya and proximal dendrites at the light microscope level Ultrastructurally, the deposits were usually associated with lysosomes Injections of CTB-gold into the caudal ventrolateral medulla or into the lateral horn of the spinal cord gave small well-defined injection sites and resulted in retrograde labelling in medullary neurons in the same locations as similarly placed injections of wheat germ agglutinin-horseradish peroxidase When injected into the superior cervical ganglion, CTB-gold was transported to nerve cell bodies in the spinal cord, but application of CTB-gold to the cut cervical sympathetic trunk did not label neurons in the spinal cord Injection of CTB-gold into the nodose ganglion retrogradely labelled neurons in the dorsal motor nucleus of the vagus and the nucleus ambiguus CTB-gold was not transported anterogradely from injections sites within the medulla Nerve fibers and cell bodies containing neuropeptides, monoamines, or neurotransmitter-synthesizing enzymes were readily immunostained after silver intensification of retrogradely transported CTB-gold Immunoreactivity for neuropeptides and enzymes was also demonstrated ultrastructurally after silver intensification and gold toning These results show that CTB-gold is retrogradely transported from nerve terminals and fibers of passage but not from damaged axons CTB-gold gives well-localized injection sites and persists in neurons for weeks Transported CTB-gold is easily visualized and its detection is compatible with light and electron microscopic immunocytochemistry These properties make CTB-gold a valuable tool for studying the connectivity and neurochemistry of pathways in the central nervous system

Body temperature alters the lipid composition of pulmonary surfactant in the Lizard ctenophorus nuchalis

Abstract: In any 24-h period the body temperature (Tb) of the central Australian agamid lizard, Ctenophorus nuchalis, may vary from 13 to 45°C; the mean preferred Tb is 37°C. We have analyzed surfactant-type lipids in lizards that underwent rapid changes in Tb from 37°C to 14, 19, 27, or 44°C. Lipids were extracted from lung lavage and lamellar body fractions, and phospholipids and cholesterol components were measured. There was no change in either the total amount or relative proportions of the different classes of phospholipids, but cooling increased the cholesterol content of lavage. An increase in the cholesterol: phospholipid ratio was evident within 2 h of cooling to 19°C and was maintained for at least 48 h. The ratio increased from 8% at 37°C, to 15% after 4 h at 19°C, and 18% after 4 h at 14°C. Possibly the increase in cholesterol promotes fluidity and absorption of surfactant within the alveoli of lizards with low Tb. Cold lizards collapse their lungs during prolonged periods of apnea and the surfactant m...