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Biomedical subjects

P Sanderson

Publications and source records attributed to P Sanderson.

At least 37 records · Page 2Linked to original sources
PubMed1995

Comparison of the effects of a range of dietary lipids upon serum and tissue lipid composition in the rat.

Since the type of fat consumed in the diet may play a role in the development of several disorders, it is important to ascertain the effects of different dietary fats upon parameters such as serum lipid levels and adipose deposition. The aim of this study was to determine the effects of feeding rats a range of fats with differing fatty acid compositions. Weanling male rats were fed for 10 weeks on a low fat (LF) diet or on one of five high fat diets, which contained 20% by weight of either hydrogenated coconut oil (HCO), olive oil (OO), safflower oil (SO), evening primrose oil (EPO) or menhaden (fish) oil (MO). Food intake, animal growth, tissue weights at sacrifice, serum and liver lipid concentrations and serum, heart, brain and adipose tissue fatty acid compositions were studied. The food intake of the LF-fed animals was greater than that of animals fed on the high fat diets; there were no differences in food intake between animals fed the high fat diets. The total energy intake was lower for animals fed on the HCO diet than for those fed on the LF, OO, EPO or MO diets; there were no other differences in energy intake between the groups. Animals fed the different diets had almost identical rates of weight gain up to 5 weeks; after this period of rapid growth, the increase in weight was slower in all groups but especially in the LF-fed animals. The LF-fed rats had a lower total weight gain and smaller final weights than rats fed on the high fat diets. Animals fed on the MO diet had a greater weight gain than those fed on the OO or EPO diets and their final weights were greater. The MO diet resulted in greatly increased liver weight compared with each of the other diets. The HCO, OO and EPO diets also increased liver weight compared with the LF diet. The total lipid content of the livers from rats fed the high fat diets was greater than that of those from rats fed the LF diet; the livers from animals fed the MO diet contained more lipid than those from animals fed each of the other diets. MO feeding increased the free cholesterol, cholesterol ester and triacylglycerol contents of the liver.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Effect of dietary restriction on protein synthesis and wound healing after surgery in the rat.

1. The healing of an abdominal muscle wound after surgery is associated with a considerable increase in the rate of protein synthesis. We have investigated whether this increase in protein synthesis is affected by chronic undernutrition, and whether this causes a delay in wound healing. 2. A group of rats was fed 58% of the voluntary food intake of a matched control group. After 7 days half the rats in each group underwent abdominal surgery. Forty-eight hours later all the rats were killed and muscle protein synthesis rate was measured by the flooding dose technique. 3. In a second experiment using the same dietary regimen rats were placed in metabolic cages after surgery and killed 7 days later. In addition to measurements of muscle protein synthesis, wound breaking strength was measured with a tensiometer and collagen content was also measured at the wound site. 4. Dietary restriction caused a loss of body weight, a decrease in nitrogen balance and a deficit in muscle protein mass. It also caused a decrease in protein synthesis rate in gastrocnemius muscle and in parts of the abdominal muscle distant from the site of the wound. However, it had no effect on the rate of muscle protein synthesis at the site of the wound either 2 or 7 days after surgery. The tensile strength and the collagen content of the wound were also unaffected by food restriction. 5. It is concluded that the wound healing process is uniquely protected from the effects of moderate undernutrition such as might be experienced by a chronically ill patient.

Abdominal Muscles↗
PubMed1994

Interaction between baricity (glucose concentration) and other factors influencing intrathecal drug spread.

The effects of intrathecal injection of 0.5% bupivacaine in solutions containing various concentrations of glucose have been studied in four groups of 20 patients. When solutions containing 0.8% glucose were injected at the L3-4 interspace the median maximum extent of block was higher, and the range of blocks wider, with the 8% solutions. All patients receiving 0.8% glucose had blocks between the T5 and T10 dermatomes, confirming previous work on the benefits of this concentration of glucose. In the two other groups 0.5% bupivacaine containing 0 or 0.8% glucose was injected at the L2-3 interspace. In both groups of patients a wider range of blocks, with a median maximum extent that was higher, was produced. These results demonstrate how glucose concentration may be used to influence the spread of intrathecal solutions and how other factors can obscure the effect of glucose concentration.

Aged↗
PubMed1992

A comparison of the costs of ceftazidime therapy and gentamicin combinations in three UK hospitals.

This study compares the utilization costs of ceftazidime therapy with those of gentamicin in combination with other antibacterial drugs. The results show that the relatively high purchase cost of ceftazidime compared to combinations is more than counterbalanced by the additional materials used for drug administration and serum antibiotic assays, even when other drugs were combined with ceftazidime. The average drug and equipment costs were 230.13 pounds for ceftazidime regimens and 253.94 pounds for gentamicin regimens. It is also shown that ceftazidime therapy is associated with a reduction in personnel time compared to gentamicin regimens. The average times per patient for administration and assay were 1 h 43 min for ceftazidime and 4 h 57 min for gentamicin regimens. We conclude that ceftazidime regimens are cheaper than gentamicin regimens when all drug and equipment costs are quantified. Moreover, the use of ceftazidime will release staff time for other purposes.

Anti-Bacterial Agents↗
PubMed1990

The influence of striatum on the substantia nigra: a study using the spreading depression technique.

Effects of changes in striatal neurone activity on substantia nigra (SN) unit activity were studied in rats. Striatal changes were produced by the spreading depression (STSD) induced by perfusing the head of striatum with 0.06 M KCl via a push-pull cannula. In the medial part (caudate) striatal neurones are silent, with the arrival of STSD they exhibit a brief excitation coinciding with the onset of a slow wave of depolarisation in the extracellular steady potential. In the lateral part (putamen) striatal neurones are active, they undergo an arrest of their spontaneous activity for about 1 minute following the brief excitation. Antidromic activation of SN reticulata (SNr) neurones was attempted from the superior colliculus (SC). The majority of the 54 SNr neurones (96%) exhibited changes in firing rate during STSD. Ten neurones underwent brief single or repetitive changes of the same duration as the brief striatal excitation. Eight presented an initial brief change of activity followed by a longer duration inverse change in firing rate. Eighteen exhibited multiple brief changes followed by or superimposed on a long lasting decrease of firing rate and 50% of them were nigrotectal neurones. Sixteen neurones presented long duration biphasic changes in firing rate. Two SNr neurones and the 12 substantia nigra compacta (SNc) neurones studied were unaffected. Some neurones received both inhibitory and facilitatory striatal controls. In total thirty-nine neurones were inhibited and 47 facilitated, the origin of these effects from caudate and putamen are discussed. The excitatory action may be due to either a direct excitatory pathway or to a relayed effect of the inhibitory GABAergic pathway.

Action Potentials↗
PubMed1990

Modulation of secretion by dopamine involves decreases in calcium and nicotinic currents in bovine chromaffin cells.

1. Catecholamine secretion from cultured bovine adrenal chromaffin cells was decreased in a dose-dependent manner by the D2 dopamine agonists apomorphine and LY 17 1555. 2. 45Ca2+ uptake was similarly inhibited and whole-cell Ca2+ currents were reduced by apomorphine. 3. These inhibitory effects of D2 agonists depended on the secretagogue used, being much more pronounced for nicotine-evoked responses compared to high K+ stimulation, indicating another possible site of action of apomorphine up-stream of Ca2+ entry. 4. Inhibition by apomorphine of nicotine-evoked responses could not be explained by competitive antagonism against nicotine or DMPP (1,1-dimethyl-4-phenyl-piperazinium iodide). 5. Apomorphine caused reductions of inward whole-cell nicotinic current evoked by ACh and nicotine. 6. Inhibition of nicotine-evoked secretion and 22Na+ influx by apomorphine were not affected by tetrodotoxin, and voltage-dependent, whole-cell Na+ currents were unaltered by apomorphine. 7. No evidence was obtained for increases in K+ conductance by apomorphine. 8. Action potentials recorded in whole-cell current clamp were blocked by apomorphine when they were triggered by nicotinic depolarization but not when they were elicited by direct electrical stimulation. 9. Inclusion of GDP-beta-S in the pipette internal solution did not affect apomorphine-dependent inhibition of nicotinic-evoked responses, while the decrease in whole-cell Ca2+ current induced by apomorphine was completely inhibited in the presence of GDP-beta-S. 10. Increases in cyclic AMP caused by cholera toxin and forskolin did not change the apomorphine-dependent inhibitory effects on nicotine-evoked secretion, indicating that changes in cyclic AMP levels caused by dopamine receptor stimulation are probably not involved.

Action Potentials↗
PubMed1986

Changes in substantia nigra pars reticulata activity following lesions of the substantia nigra pars compacta.

Single unit activity of substantia nigra reticulata (SNr) neurons was recorded in normal rats and bilaterally in rats subjected to a unilateral 6-hydroxydopamine lesion of the substantia nigra compacta 2-4 weeks previously. Lesions were assessed by rotational behaviour to apomorphine. In normal rats the majority of neurons (63%) showed a regular firing pattern. Following lesion the percentage of these cells was similar in the SNr contralateral to the lesion but decreased on the lesioned side to 26%, whereas bursting activity developed (37% vs 5% in normal rats). The mean firing rate of reticulata neurons was slightly increased after lesion, but not statistically significant.

Action Potentials↗
PubMed1986

Cortifugal influences on dorsal column nuclei: an electrophysiological study in the rat using the cortical spreading depression technique.

The sign and duration of corticofugal effects on the extracellularly recorded spontaneous activity of cuneate and gracile neurons were examined by means of the cortical spreading depression technique (CSD). Among the 40 units studied 22 showed changes in their spontaneous firing rate during the passage of a CSD. Changes were of either short (5-20 s) or long (greater than 20-140 s) duration. Increases and decreases in activity, as well as sequences of both types of alteration were observed. Short duration changes were more frequent and much more pronounced than those of long duration. From their time course and intensity the short duration effects seem to be related to the brief high frequency cortical neuron discharge that precedes the cortical silence due to CSD, whereas the long lasting effects seem related to the cortical block. It is concluded that the most important corticofugal effects on gracile and cuneate neurons are phasic in nature and the sensorimotor cortical regions were found to be responsible for these influences.

Animals↗
PubMed1985

Effect of microstimulation of movement-evoking cortical foci on the activity of neurons on the dorsal column nuclei.

Cortical foci in which stimulation produced movement in either the forelimb or hindlimb were isolated in rats. In each experiment, two foci were selected: one for movement in the forelimb, and the other in the hindlimb. Stimulation was subsequently reduced in order to avoid eliciting a movement, and the effects of this stimulation on activity of gracile and cuneate neurons were examined. Both excitation and inhibition were observed and were found to be arranged in a somatotopic manner. Excitation was almost exclusively obtained when the receptive field (RF) of a given neuron corresponded to the body surfaces overlying the joints involved in the cortically evoked movement. A high percentage of neurons with RFs on body surfaces corresponding to, or adjacent to, the region of cortically induced movement were inhibited, while the activity of neurons with RFs distant to the site of movement was seldom modified. These results suggest that cortical influences exerted on the dorsal column nuclei (DCN) in rats are organized in a somatotopic manner.

Animals↗
PubMed1984

Pivmecillinam for bacteriuria in pregnancy.

Pivmecillinam was given to 44 women with bacteriuria in pregnancy. Treatment was successful in 33 (87%) out of the 38 patients assessed. Thirty women subsequently received at random either a low-dose of pivmecillinam for up to three months or acted as a control group. Further bacteriuric episodes during pregnancy were recorded only in three patients in the control group. Thirty-nine out of the 41 women followed to term delivered healthy babies. One infant was stillborn and another child had a cleft palate. Neither was considered to be related to treatment with pivmecillinam.

Adolescent↗
PubMed1984

[Leão's spreading depression in the study of the relationship of central structures].

The use of Leão's spreading depression for studying the action of connections between central structures is examined. Extracellular recordings of cortical and striatal spreading depressions with single microelectrodes are presented using both a DC channel and spike recordings systems. Striatal spreading depression was produced by peristaltic perfusion of a KC1 solution via a push-pull cannula system. The characteristics of cortical and striatal spreading depressions were studied and their effects on antidromically provoked cellular spikes. Using double microelectrode recordings modifications of spontaneous activity provoked by cortical spreading depression were examined in n. ventralis posterior (VP) and centralis lateralis (CL) of the thalamus. In both nuclei a silence corresponding to the block of spontaneous activity of a localised cortical area was observed. The controls originated from different cortical regions for each nucleus. The discharge preceeding the onset of the spreading depression slow wave is reflected by a similar discharge in VP but not in CL. The differences in the frequency following of CL and VP was examined in order to explain this discrepancy. The results just summarized can be explained if we accept that a tonic facilitatory control exists between localised cortical areas and the two thalamic nuclei studied. Similar experiments were performed to study the controls exerted by cortical areas on dorsal column nuclei. Only phasic transitory effects were observed which were either an increase or a decrease in activity. These facilitatory or depressive effects were attributed to the initial excitation signalling the propagation of a cortical spreading depression. No tonic effects were observed. Striatal spreading depression was not accompanied by a cortical effect but on the contrary the activity of cells in substantia nigra was significantly altered. In pars reticulata two populations could be distinguished. The first presented a phasic increase followed by a long period of decreased activity, they are proposed to be under the control of striatum via an excitatory pathway. The second was initially depressed then presented a long period of increased activity. This probably reflects the block of an inhibitory striato-nigral pathway. Both striato nigral effects were tonic in nature. The possibility of separating the effects due to cortical excitation or cortical block are discussed as well as the problems of interpretation of long distance changes in cellular activity.

Animals↗