Showing papers by "Flinders University published in 1991"

Electron momentum spectroscopy of atoms and molecules

Abstract: Unique information about the motion and correlation of valence electrons in atoms, molecules and their ions is obtained from electron-impact ionization reactions near the Bethe ridge at total energies of the order of 1000 eV or higher. This is electron momentum spectroscopy. The history, theory and practice of the field are discussed and its value is shown by numerous examples.

The UDP glucuronosyltransferase gene superfamily: suggested nomenclature based on evolutionary divergence.

Abstract: A nomenclature system for the UDP glucuronosyltransferase superfamily is proposed, based on divergent evolution of the genes. A total of 26 distinct cDNAs in five mammalian species have been sequenced to date. Comparison of the deduced amino acid sequences leads to the definition of two families and a total of three subfamilies. For naming each gene, we propose that the root symbol UGT for human (Ugt for mouse), representing "UDP glucuronosyltransferase," be followed by an Arabic number denoting the family, a letter designating the subfamily, and an Arabic numeral representing the individual gene within the family or sub-family (hyphen before the Arabic number for mouse), e.g., human UGT2B1 and murine Ugt2b-1. Whereas the gene and cDNA should be italicized, the corresponding transcript, protein, and enzyme activity should not be written with lowercase letters or in italics, e.g., human or murine UGT2B1. Recent experimental evidence suggests that several exons of the UGT1 gene might be shared, ind...

Calretinin immunoreactivity in cholinergic motor neurones, interneurones and vasomotor neurones in the guinea-pig small intestine.

Abstract: Immunoreactivity for calretinin, a calcium-binding protein, was studied in neurones in the guinea-pig small intestine. 26 +/- 1% of myenteric neurones and 12 +/- 3% of submucous neurones were immunoreactive for calretinin. All calretinin-immunoreactive neurones were also immunoreactive for choline acetyltransferase and hence are likely to be cholinergic. In the myenteric plexus, two subtypes of Dogiel type-I calretinin-immunoreactive neurones could be distinguished from their projections and neurochemical coding. Some calretinin-immunoreactive myenteric neurones had short projections to the tertiary plexus, and hence are likely to be cholinergic motor neurones to the longitudinal muscle. Some of these cells were also immunoreactive for substance P. The remaining myenteric neurones, immunoreactive for calretinin, enkephalin, neurofilament protein triplet and substance P, are likely to be orad-projecting, cholinergic interneurones. Calretinin immunoreactivity was also found in cholinergic neurones in the submucosa, which project to the submucosal vasculature and mucosal glands, and which are likely to mediate vasodilation. Thus, calretinin immunoreactivity in the guinea-pig small intestine is confined to three functional classes of cholinergic neurones. It is possible, for the first time, to distinguish these classes of cells from other enteric neurones.

Different populations of parvalbumin- and calbindin-D28k-immunoreactive neurons contain GABA and accumulate 3H-D-aspartate in the dorsal horn of the rat spinal cord.

Abstract: The colocalization of parvalbumin (PV), calbindin-D28k (CaBP), GABA immunoreactivities, and the ability to accumulate 3H-D-aspartate selectively were investigated in neurons of laminae I-IV of the dorsal horn of the rat spinal cord. Following injection of 3H-D-aspartate into the basal dorsal horn (laminae IV-VI), perikarya selectively accumulating 3H-D-aspartate were detected in araldite embedded semithin sections by autoradiography, and consecutive semithin sections were treated to reveal PV, CaBP and GABA by postembedding immunocytochemistry. Perikarya accumulating 3H-D-aspartate were found exclusively in laminae I-III, and no labelled somata were found in deeper layers or in the intermediolateral column although the labelled amino acid clearly spread to these regions. More than half of the labelled cells were localized in lamina II. In this layer, 16.4% of 3H-D-aspartate-labelled perikarya were also stained for CaBP. In contrast to CaBP, PV or GABA was never detected in neurons accumulating 3H-D-aspartate. A high proportion of PV-immunoreactive perikarya were also stained for GABA in laminae II and III (70.0% and 61.2% respectively). However, the majority of CaBP-immunoreactive perikarya were GABA-negative. GABA-immunoreactivity was found in less than 2% of the total population of cells stained for CaBP in laminae I-IV. A significant proportion of the GABA-negative but PV-immunoreactive neurons also showed CaBP-immunoreactivity in laminae II and IV. These results show that out of the two calcium-binding proteins, CaBP is a characteristic protein of a small subpopulation of neurons using excitatory amino acids and PV is a characteristic protein of a subpopulation of neurons utilizing GABA as a transmitter. However, both proteins are present in additional subgroups of neurons, and neuronal populations using inhibitory or excitatory amino acid transmitters are heterogeneous with regard to their content of calcium-binding proteins in the dorsal horn of the rat spinal cord.

Selective Impairment of Respiration in Mitochondria Isolated from Brain Subregions Following Transient Forebrain Ischemia in the Rat

Abstract: Using Percoll density gradient centrifugation, free (nonsynaptosomal) mitochondria were isolated from the dorsal-lateral striatum and paramedian neocortex of rats during complete forebrain ischemia and reperfusion. Mitochondria prepared from either region after 30 min of ischemia showed decreased state 3 (ADP and substrate present) and uncoupled respiration rates (19-45% reductions) with pyruvate plus malate as substrates, whereas state 4 respiration (no ADP present) was preserved. At 6 h of recirculation, state 3 and uncoupled respiration rates for mitochondria from the paramedian neocortex (a region resistant to ischemic damage) were similar to or even increased compared with control values. By contrast, in mitochondria from the dorsal-lateral striatum (a region containing neurons susceptible to global ischemia), decreases in state 3 and uncoupled respiration rates (25 and 30% less than control values) were again observed after 6 h of recirculation. With succinate as respiratory substrate, however, no significant differences from control values were found in either region at this time point. By 24 h of recirculation, respiratory activity with either pyruvate plus malate or succinate was greatly reduced in samples from the dorsal-lateral striatum, probably reflecting complete loss of function in some organelles. In contrast with these marked changes in free mitochondria, the respiratory properties of synaptosomal mitochondria, assessed from measurements in unfractionated homogenates, were unchanged from controls in the dorsal-lateral striatum at each of the time points studied, but showed reductions (19-22%) during ischemia and after 24 h of recirculation in the paramedian neocortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasomotor, pilomotor and secretomotor neurons distinguished by size and neuropeptide content in superior cervical ganglia of mice

Abstract: Populations of postganglionic sympathetic neurons projecting to cranial targets from the superior cervical ganglia of mice were identified by retrograde axonal tracing with Fast blue combined with double-labelling immunofluorescence to detect immunoreactivity to tyrosine hydroxylase and neuropeptide Y. Nearly all neurons in the ganglion contained tyrosine hydroxylase immunoreactivity, but only about 50% of them also contained immunoreactivity to neuropeptide Y. The maximum diameter of cells with immunoreactivity to neuropeptide Y was significantly smaller than that of cells without it. Terminal axons containing immunoreactivity to both neuropeptide Y and tyrosine hydroxylase occurred around blood vessels supplying most cranial tissues, including the skin. Axons with immunoreactivity to tyrosine hydroxylase but not to neuropeptide Y innervated the piloerector muscles and the acini of the salivary glands. After injection of Fast blue into the skin or the submandibular salivary gland, populations of vasomotor, pilomotor and secretomotor neurons could be distinguished by soma size and by neuropeptide Y immunoreactivity. Neurons projecting to the salivary glands were the largest (mean diameter: 32 μm) and lacked immunoreactivity to neuropeptide Y; neurons projecting to cutaneous blood vessels were the smallest (mean diameter: 19 μm) and contained immunoreactivity to neuropeptide Y; neurons projecting to piloerector muscles were intermediate in size (mean diameter: 23 μm) and lacked neuropeptide Y immunoreactivity. A cluster analysis procedure confirmed that soma size and peptide content together identify major functional populations of neurons in the superior cervical ganglia of mice.

Ramifications of the axons of AH-neurons injected with the intracellular marker biocytin in the myenteric plexus of the guinea pig small intestine

Abstract: The projections and terminal ramifications of electrophysiologically characterized myenteric neurons of the guinea pig small intestine were studied after intracellular injection of the marker substance biocytin. Myenteric neurons were impaled with microelectrodes containing 4% biocytin in 2 M KCl (pH 7.4) and characterized electrophysiologically as either AH-neurons or S-neurons. AH-neurons were neurons in which action potentials were followed by prolonged after-hyperpolarizations (lasting greater than 4 seconds). S-neurons were neurons in which such hyperpolarizations were not seen. Electrical stimulation of internodal strands evoked prominent fast excitatory synaptic potentials in S-neurons, but not in AH-neurons. Biocytin was injected electrophoretically into the impaled AH-neurons by passage of hyperpolarizing current (0.6-0.8 nA for 5-15 minutes) through the recording electrode. The preparation was then fixed in Zamboni's fixative, dehydrated, and exposed to avidin coupled to horseradish peroxidase which allowed the injected biocytin to be visualised via a diaminobenzidine reaction. In many cases, the injected biocytin appeared to fill all the processes of injected AH-neurons that ramified within the myenteric plexus. The filled processes included axons running up to 4 mm within the plexus and profuse varicose terminals ramifying within both the ganglion containing the injected cell body and nearby ganglia. Most (90%) cell bodies of the injected AH-neurons had the morphology of Dogiel type II neurons; large, mostly smooth cell bodies with few short processes and several long processes. The other 10% of the AH-neurons had similar cell bodies and long processes but also had prominent short filamentous processes. This population was termed dendritic AH-neurons. The projections and terminals of 28 AH/Dogiel type II neurons and 7 dendritic AH-neurons were analysed in detail. Both types of neurons project circumferentially to provide terminals to nearby ganglia, but the AH/Dogiel type II neurons also provide terminals to their own ganglia while the dendritic AH-neurons typically do not. Although many of the injected AH-neurons had projections orally or anally along the intestine no evidence for a preferential direction of projection was obtained. Analysis of the areas and distributions of the terminal fields of the AH/Dogiel type II neurons suggests that each may contact several other myenteric neurons and that each myenteric neuron may receive input from about ten AH/Dogiel type II neurons.

Human Values, Global Self-Esteem, and Belief in a Just World

Abstract: Relations were investigated between global self-esteem, just world beliefs, and value priorities in two large samples of Australian high-school (N= 953) and university students (N= 361). Principal component factor analyses involving the importance ratings for each of the Rokeach terminal and instrumental values showed that values could be classified into the following eight value domains for both samples: positive affiliation, universal prosocial, mature accomplishment, comfort/stimulation, security/salvation, self-directed competence, restrictive conformity, and prosocial concern. These value domains overlapped with but were not identical to the classification of motivational domains proposed by Schwartz and Bilsky (1987). As predicted, global self-esteem (assessed by the Rosenberg Self-Esteem Scale) was positively related to the importance of values in domains concerned with achievement, competence, and self-direction, and just world beliefs (assessed by the Just World Scale) were positively related to values in the restrictive conformity domain. Gender differences occurred in regard to the value domains and in the relation of prosocial values to global self-esteem in the older university sample. The results were discussed in relation to other studies of the structure of human values and other research on self-esteem and belief in a just world.

Relationship between phenytoin and tolbutamide hydroxylations in human liver microsomes.

Abstract: 1. The metabolic interaction of phenytoin and tolbutamide in human liver microsomes was investigated. 2. Phenytoin 4-hydroxylation (mean Km 29.6 microM, n = 3) was competitively inhibited by tolbutamide (mean Ki 106.2 microM, n = 3) and tolbutamide methylhydroxylation (mean Km 85.6 microM, n = 3) was competitively inhibited by phenytoin (mean Ki 22.6 microM, n = 3). 3. A significant correlation was obtained between phenytoin and tolbutamide hydroxylations in microsomes from 18 human livers (rs = 0.82, P less than 0.001). 4. Sulphaphenazole was a potent inhibitor of both phenytoin and tolbutamide hydroxylations with IC50 values of 0.4 microM and 0.6 microM, respectively. 5. Mephenytoin was a poor inhibitor of both phenytoin and tolbutamide hydroxylations with IC50 values greater than 400 microM for both reactions. 6. Anti-rabbit P450IIC3 IgG inhibited both phenytoin and tolbutamide hydroxylations in human liver microsomes by 62 and 68%, respectively. 7. These in vitro studies are consistent with phenytoin 4-hydroxylation and tolbutamide methylhydroxylation being catalysed by the same cytochrome P450 isozyme(s) in human liver microsomes.

The use of stable isotopes of water in characterising the source of water in vegetation

Abstract: The use of stable isotopes of water as tracers in characterising the source of water in vegetation is tried in three field situations. Initially, methodological aspects of the uptake of water into plant tissue, water movement from roots to tops and recovery from stem-wood by distillation are considered. Using tracers of deuterium and oxygen-18, diffusion of water into lettuce leaf tissue was demonstrated to occur as the whole molecule, equilibrating in 24 h. It is considered from the similar tissue density that diffusion of water into roots would be similar. Distillation in toluene or kerosene to recover water from various materials found small decreases in deuterium composition of the recovered water: − 2.3‰ when recovering water from pine wood, −1.4‰ from potting mix and −3.2‰ from wood of native plants, while water recovered from lettuce leaf was not subject to such effects. These decreases are correlated to the proportion of organic matter in the materials, and may relate to decomposition of a component of this. Uptake of water by potted Hordeum vulgare, Atriplex nummularia, A. rhagodiodes, A. vesicaria. Callitris preissii, Casuarina glauca, Eucalyptus oleosa, E. citriodora and Maireana sedifolia was found to be relatively free of further fractionation. In field studies, comparison of the isotopic composition of water from stems of Hordeum vulgare, Maireana sedifolia and Pinus radiata and from adjacent soil profiles suggested that the depth of extraction of water by roots varied with water availability and rooting depth. Examination of the stable isotopes of soil and sap water in addition to soil water contents provides a more realistic interpretation of plant water source than obtained by studying soil water content alone.

Sleep difficulties, pain and other correlates.

Abstract: . A multiple regression analysis was used with variables relevant to sleeping problems from a large community health survey in South Australia. The variables that were found to be most strongly correlated with sleep problems were, in order of importance, pain, anxiety, age, somatic health and annual household income, all of which accounted for 22% of the variance. Weight problems, depression and sex of the respondent were not so important in this analysis. Arthritis, which often increases with age, appeared to be most strongly associated with pain, explaining in part why sleeping problems increase with age. Anxiety, pain and poor somatic health were most strongly associated with lying awake at night or sleeping badly, and anxiety and pain were most strongly correlated with taking longer to get to sleep. Poor somatic health and anxiety were most strongly associated with waking early, and age and pain were the most important variables in taking tablets to aid sleep.

Substance P-containing neurons in the mesopontine tegmentum are severely affected in Parkinson's disease.

Abstract: Substance P immunoreactive (SP+) neurons were analysed quantitatively in serial sections of the mesopontine tegmentum in 6 patients with idiopathic Parkinson's disease and 5 age-matched normal controls. In the tegmentum of the Parkinson's disease brains many SP+ neurons contained swollen, twisted neuronal processes as well as Lewy bodies. There were significant reductions in the total number of SP+ neurons in the pedunculopontine tegmental nucleus (loss 43%), in the laterodorsal tegmental nucleus (loss 28%), in the oral pontine reticular nucleus (loss 41%) and in the median raphe nucleus (loss 76%). It was the large SP+ (greater than 20 microns) neurons that were particularly affected. In our control group we did not document a significant relationship between age at death and number of SP+ neurons in these tegmental nuclei or between age at death and number of pigmented neurons in the locus coeruleus. In contrast, in patients with Parkinson's disease, there was a strong inverse relationship between age at death and numbers of SP+ and pigmented neurons. Our findings suggest an interaction between the pathophysiological mechanisms initiated by Parkinson's disease and other processes related to ageing. Since tegmental SP+ neurons are affected by the primary pathological processes underlying Parkinson's disease as severely as catecholamine-synthesizing neurons are affected, theories of pathogenesis and therapeutic strategies in Parkinson's disease will need to take into account the involvement of these SP+ neurons.

Prosencephalic connections of striate and extrastriate areas of rat visual cortex.

Abstract: Afferent connections of rat primary visual cortex (area 17 or V1 area) and the rostral and caudal parts of areas 18a and 18b were studied, by placing in each of the areas, small electrophoretic injections of enzyme horseradish peroxidase (HRP) or wheat germ agglutinated-HRP. The results indicate that: 1) each of the areas has a distinct pattern of distribution of afferent neurons in the ipsilateral visual thalamus — area 17 receives its principal thalamic input from the dorsal lateral geniculate nucleus, the caudal parts of areas 18a and 18b receive a major thalamic input from the lateral posterior nucleus and a minor input from the posterior nucleus, while the rostral parts of areas 18a and 18b receive a major input from the posterior nucleus, and a minor projection from the lateral posterior nucleus; 2) the rostral and caudal parts of areas 18a and 18b each receive an associational input from area 17; 3) the rostral parts of areas 18a and 18b each receive associational input from three different extrastriate regions, the caudal part of the same extrastriate area, and the rostral and caudal parts of the other extrastriate area, whereas the caudal parts of areas 18a and 18b receive associational inputs only from one or two extrastriate regions; 4) area 17, area 18b and rostral area 18a each receive a substantial associational input from lamina V of the caudal part of the frontal eye field (FEF) in the motor cortex; however the input from the FEF to caudal area 18a (if present) is very small; 5) The extrastriate areas studied receive associational input from the restrosplenial cingulate area 29d; however, the input from area 29d to area 17 appears to be very small. The distinct patterns of distribution of prosencephalic afferents suggest to us that multiple retinotopically organized areas described previously in the rat cortex (cf Montero 1981; Espinoza and Thomas 1983) represent functionally distinct areas.

Neurons in rabbit caudal ventrolateral medulla inhibit bulbospinal barosensitive neurons in rostral medulla

Abstract: We made extracellular recordings from 104 spinally projecting neurons in the rostral ventrolateral medulla of urethan-anesthetized rabbits to test whether inhibitory vasomotor neurons in the caudal ventrolateral medulla act by inhibiting rostral sympathoexcitatory neurons. The median conduction velocity was 8.3 m/s, and the median discharge rate was 2.9 spikes/s. Raising arterial pressure with intravenous phenylephrine inhibited 88% of 77 neurons tested. The remaining units were excited. Lowering arterial pressure with nitroprusside excited 90% of 30 neurons tested. Remaining units were unaffected. Ninety-one percent of 58 rostral neurons inhibited by phenylephrine were also inhibited by injection of L-glutamate into the caudal ventrolateral medulla and 81% of 43 tested were excited by caudal injection of gamma-aminobutyric acid. These results confirm our suggestion [Brain Res. 253: 161-171, 1982; Am. J. Physiol. 254 (Heart Circ. Physiol. 23): H686-H692, 1988] and the findings of S. K. Agarwal, A. J. Gelsema, and F. R. Calaresu [Am. J. Physiol. 257 (Regulatory Integrative Comp. Physiol. 26): R265-R270, 1989]. The depressor neurons in the caudal medulla act substantially by inhibition of spinally projecting sympathoexcitatory neurons in the rostral medulla. All rostral units excited by phenylephrine were also excited by injections of L-glutamate into the caudal ventrolateral medulla, suggesting that some sympathoinhibition of baroreceptor and caudal medullary origin may take place in the spinal cord and be mediated by a subpopulation of rostral sympathoinhibitory neurons.

IL-4 suppresses IL-1β, TNF-α and PGE2 production by human peritoneal macrophages

Abstract: Human interleukin-4 (IL-4) down-regulates IL-1 and tumour necrosis factor-alpha (TNF-alpha) production by monocytes stimulated in vitro. In contrast, in studies of activation of murine macrophages, both stimulatory and inhibitory functions of murine IL-4 have been documented. To investigate whether opposing activities of IL-4 reflect a difference in the target cell studied, due either to cell maturation or the site from which the cells were isolated, we examined the effect of IL-4 on human peritoneal macrophage production of IL-1 beta, TNF-alpha and prostaglandin E2 (PGE2). Human peritoneal macrophages stimulated with lipopolysaccharide (LPS) produced levels of these mediators that were at least as great as those previously reported for monocytes. Similarly, IL-4 was inhibitory for peritoneal macrophage mediator production after in vitro stimulation. Thus, IL-4 has effects on human peritoneal macrophages similar to those on blood monocytes. In addition, as it down-regulates mediator production by cells that have left the circulation, it may be important in controlling the immune response in tissues.

The psychological impact of unemployment and unsatisfactory employment in young men and women: Longitudinal and cross-sectional data

Abstract: Data are presented from the seventh wave of a longitudinal study of school-leavers that commenced in 1980. Four groups were compared: satisfied employed, dissatisfied employed, unemployed and full-time tertiary students. The groups differed initially with respect to only one background variable, teacher-rated academic potential, and did not differ on any of the psychological measures of well-being. In general, the unemployed and dissatisfied employed groups displayed poorer psychological well-being than the satisfied employed and student groups on a range of measures. The longitudinal data suggested that this was because the two disadvantaged groups showed smaller improvements than the others, rather than any deterioration. The results also suggested that for the males unemployment was worse than unsatisfactory employment, but that for the females unsatisfactory employment was worse than unemployment.

On a periodic neutral logistic equation

Abstract: The oscillatory and asymptotic behaviour of the positive solutions of the autonomous neutral delay logistic equationwith r, c, T, K ∈ (0, ∞) has been recently investigated in [2]. More recently the dynamics of the periodic delay logistic equationin which r, K are periodic functions of period τ and m is a positive integer is considered in [6]. The purpose of the following analysis is to obtain sufficient conditions for the existence and linear asymptotic stability of a positive periodic solution of a periodic neutral delay logistic equationin which Ṅ denotes and r, K, c are positive continuous periodic functions of period τ at and m is a positive integer. For the origin and biological relevance of (1.3) we refer to [2].

A randomised study of outcomes in a defined group of acutely ill elderly patients managed in a geriatric assessment unit or a general medical unit.

Abstract: The aim of this study was to identify differences in the medical management and clinical outcome in a group of elderly patients admitted to a designated geriatric assessment unit (GAU) or to two general medical units (GMUs). A prospective randomised controlled trial was undertaken in 267 patients aged 70 years and over (mean age = 78.3 years). Following discharge from hospital, patients were followed up at three monthly intervals for a total of 12 months. At the time of discharge, no significant differences were found in inpatient management, length of stay, mortality rates, discharge rates to institutional care or utilisation of community services in patients admitted to the GAU and the GMUs. Similarly, no significant differences were found at three, six, nine, and 12 month follow up in case fatality, activities of daily living indices, mental health status, rates of institutional referral and the level of community service support in patients admitted to the GAU and the GMUs studied. These findings do not show any advantage for the unselected 70 + acutely ill elderly patient who is admitted to a designated geriatric assessment unit rather than to a general medical unit. Therefore, an admission policy to GAU, based solely on age 70 + is medically inappropriate and cost-inefficient. Evidence from other sources suggests that an age cohort of acutely admitted patients beyond 80 years may well have returned more optimistic findings for the GAU. In future, GAUs will require a more selective admission policy to maximise the benefits of their rehabilitative and interdisciplinary approach. (Aust NZ J Med 1991; 21: 230–234.)