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A D Smith

Publications and source records attributed to A D Smith.

At least 361 records · Page 20Linked to original sources
PubMed1986

The effects of dietary (n-3) fatty acid supplementation on lipid dynamics and composition in rat lymphocytes and liver microsomes.

Rats were fed diets devoid of (n-3) fatty acids (olive oil supplementation) or high in (n-3) fatty acids (fish oil supplementation) for a period of 10 days. In spleen lymphocytes and liver microsomes derived from animals fed fish oil diets, relatively high levels of (n-3) eicosapentaenoic (20:5), docosapentaenoic (22:5) and docosahexaenoic acids (22:6) were obtained compared to minimal levels when fed the olive oil diet. When the average lipid motional properties were examined by measuring the fluorescence anisotropy of diphenylhexatriene, no significant different was found between intact liver microsomes from animals fed the two diets. However, when lipid motion was examined in vesicles of phosphatidylcholine, isolated from the microsomes from fish oil fed animals (21.4% (n-3) fatty acids), the fluorescence anisotropy was significantly less than the corresponding phosphatidylcholine from olive oil fed animals (5.6% (n-3) fatty acids), indicating a more disordered or fluid bilayer in the presence of higher levels of (n-3) fatty acids. Phosphatidylethanolamine (n-3) fatty acids were also elevated after fish oil supplementation (41.3% of total fatty acids), compared to the level after olive oil supplementation (21.4%). The major effect of the fish oil supplementation was a replacement of (n-6) arachidonic acid by the (n-3) fatty acids and when this was 'modeled', using liposomes of synthetic lipids, 1-palmitoyl-2-arachidonyl(n-6) or docosahexaenoyl(n-3)-phosphatidylcholine, significant differences in lipid motional properties were found, with the docosahexaenoate conferring a more disordered or fluid lipid environment. Thus it appears that although lipid order/fluidity can be significantly decreased by increases in the highly unsaturated (n-3) fatty acid levels, alterations in membrane domain organization and/or phospholipid molecular species composition effectively compensated for the changes, at least as far as average lipid motional properties in the intact membranes was concerned.

Animals↗
PubMed1986

Two species of phospholipase C isolated from lymphocytes produce specific ratios of inositol phosphate products.

Chromatography of the soluble porcine lymphocyte phospholipase C on cellulose phosphate resolves the activity into two species. An HPLC method is described for separating the enzyme products, Ins 1,2 greater than P and Ins 1P. Use of these methods reveals that the two iso-enzymes liberate, with a high degree of reproducibility, characteristic ratios of the two products. This suggests that the amount of each product produced is an inherent property of the enzyme mechanism.

Animals↗
PubMed1986

Relationships between catecholaminergic neurons and cholecystokinin-containing neurons in the caudal part of the dorsomedial medulla oblongata of the rat: light and electron microscopic observations by the 'mirror technique'.

The 'mirror technique' was used in immuno-electron microscopy to examine the synaptic relationships between neuronal structures containing catecholamines and cholecystokinin (CCK) in the caudal part of the dorsomedial medulla oblongata in the rat, using antisera against tyrosine hydroxylase and CCK. CCK-immunoreactive axon terminals made synaptic contacts with catecholaminergic neurons. Some of these catecholaminergic neurons contained CCK.

Animals↗
PubMed1986

Ultrastructural evidence of dopaminergic input to enkephalinergic neurons in rat neostriatum.

The synaptic relationship between neuronal structures reacting with antibodies to tyrosine hydroxylase (TH) and Leu- or Met-enkephalin (ENK) was studied by the 'mirror technique' in adjacent sections of rat neostriatum. TH-immunoreactive (TH-IR) axonal boutons surrounding the neural perikarya and proximal dendrites of ENK-immunoreactive (ENK-IR) neurons were very thin (0.1-0.4 micrograms). They contained many small clear vesicles and sometimes had symmetrical membrane specializations. This provides morphological evidence for catecholaminergic, presumably dopaminergic inputs to rat striatal enkephalin neurons.

Animals↗
PubMed1986

Influence of dietary lipids on the effect of chlorpromazine on membrane properties of rabbit red cells.

The effect of diets containing different types of common natural oils on physical properties of red cells was investigated by using rabbits. The rabbits were fed for 18 months on a standard diet in which 8% of its energy content was provided by safflower oil and 32% energy by either more safflower oil or fish oil, linseed oil, olive oil or palm oil. Erythrocyte deformability was significantly decreased by the fish oil diet compared with each of the other diets. Osmotic fragility was significantly less (66 mM) for red cells from rabbits fed on the linseed oil diet, and significantly greater (71 mM) for red cells from rabbits on the fish oil diet, than for red cells from rabbits on the other three diets which did not differ significantly from each other (68 mM). With rabbits on the standard diet, the resistance of their erythrocytes to osmotic haemolysis was increased by chlorpromazine at concentrations below and decreased by concentrations above 30 microM. The dietary oils caused significant changes in the effects of chlorpromazine on osmotic fragility. The concentration at which the effect of chlorpromazine reversed from antihaemolytic to prohaemolytic was decreased by the safflower and linseed oil diets and increased by the fish oil diet, compared with the olive and palm oil diets. Analysis of the fatty acid compositions of the dietary oils on the one hand and of the red cell phospholipids on the other established, specifically, that in the presence of 30 microM chlorpromazine the percentage haemolysis was directly proportional to the linoleate content of the red cell phospholipids.

Animals↗
PubMed1986

Percutaneous nephrolithotomy: analysis of 500 consecutive cases.

The first 500 patients who underwent percutaneous stone removal at our hospital and who have been evaluated for at least 8 months were reviewed. Comparison of the first 100 patients with the entire series showed a sharp improvement in the success rate as the radiologic and urologic team gained experience. The success rate for simple pelvicaliceal stones was 98% in the entire series (vs. 89% in the first 100 cases) and 87% for staghorn calculi. The most common complication was bleeding, with 12% of the patients requiring transfusion. Other complications include infection (0.6%), retained stone fragments (4%), and ureteropelvic junction stricture (1%). There was 1 death, an obese diabetic woman who suffered a myocardial infarction. Successful stone extraction requires a properly placed nephrostomy tract, and radiologic and urologic expertise. The advent of extracorporeal shock-wave lithotripsy will not abolish the need for nephrostolithotomy.

Adolescent↗
PubMed1986

Hexokinase A from mammalian brain: comparative peptide mapping and immunological studies with monoclonal antibodies.

Immunological reactivity of partially purified hexokinase A (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1) from brain of several vertebrate species has been compared by using enzyme-linked immunosorbent assay and seven monoclonal antibodies raised against the rat brain enzyme. The epitopes recognized by three of these antibodies have been rather widely conserved among the species examined (rat, mouse, guinea pig, rabbit, cat, dog, sheep, cow, pig, chicken), while this was not the case for the epitopes recognized by the other antibodies, which differed markedly in their distribution among these species. The domain structure of these enzymes has been examined by peptide mapping (after limited tryptic digestion) in conjunction with immunoblotting techniques employing monoclonal antibodies. The results indicate that the overall domain structure of these enzymes is similar to that previously described for rat brain hexokinase A, but that there are significant differences in the size of these domains in enzymes from different species.

Animals↗
PubMed1986

Endourologic approach to transplant kidney.

Two significant procedures, namely lithotripsy of staghorn calculus and dilatation of a stenotic calyceal infundibulum, were performed endourologically in a renal allograft drained by an ileal conduit. This is another example of the versatility of these minimally invasive urologic methods.

Adult↗
PubMed1986

Technique and trial of continent ileocystostomy.

To overcome the problem of incontinence which failed to respond to standard measures, an animal model was designed for continent diversion without cystectomy. A tapered terminal ileal segment was implanted in a submucosal tunnel on the anterior aspect of the bladder, and the proximal end of the segment was brought out to the abdominal wall as a stoma that is catheterized intermittently. Ileocystostomy provided continent diversion in 10 dogs at intravesical pressures as high as 45 cm H2O, and there were no changes in serum electrolytes, creatinine, or urea nitrogen concentration.

Animals↗
PubMed1986

Cholecystokinin-immunoreactive boutons in synaptic contact with hippocampal pyramidal neurons that project to the nucleus accumbens.

Neurons in the hippocampal formation of the rat that project to the medial nucleus accumbens were identified following the retrograde transport of a conjugate of horseradish peroxidase with wheat germ agglutinin. The great majority of such projecting neurons were located in the ventral subiculum and were pyramidal in shape; the pyramidal nature of 25 such retrogradely labelled neurons was established by Golgi impregnation. In material processed to reveal both retrogradely labelled cells and cholecystokinin-immunoreactivity, no immunoreactive projecting neurons were found. However, 48 identified projecting neurons, probably pyramidal, were found to receive input from cholecystokinin-immunoreactive boutons that formed symmetrical synaptic contacts with the soma or proximal dendrites. It is suggested that one function of cholecystokinin-immunoreactive neurons in the hippocampal formation might be to influence the output of the pyramidal neurons that project to the nucleus accumbens. Since this pathway is one of the main links between the limbic system and the basal ganglia, it is conceivable that changes in the cholecystokinin levels in the hippocampus, as found in schizophrenia, might influence behaviour through the pathway connecting the hippocampus with the nucleus accumbens.

Animals↗
PubMed1986

Synaptic connections of axo-axonic (chandelier) cells in human epileptic temporal cortex.

The human temporal cortex contains a type of interneuron, identified by Golgi impregnation which, like the axo-axonic or chandelier cells found in animals, establishes Gray's type II synaptic contacts exclusively with the axon initial segments of pyramidal cells. Each terminal segment is composed of 3-12 boutons to form a "chandelier"-like appearance. For the two human axo-axonic cells analysed in this study we could identify 269 and 86 bouton rows respectively, which represents an equivalent number of postsynaptic pyramidal cells. A terminal bouton row from one of these Golgi-impregnated cells was shown to be in synaptic contact with the axon initial segment of a Golgi-impregnated pyramidal cell. The very specific nature of the target of axo-axonic cells, together with their highly divergent axonal arborization, means that they are ideally placed to control the output of a large population of pyramidal cells. Since previous studies in animals have shown the GABAergic nature of axo-axonic cells it is possible that human axo-axonic cells could be involved in the generation of epileptic activity or in the control of its propagation.

Adolescent↗
PubMed1986

Staghorn calculi: percutaneous extraction versus anatrophic nephrolithotomy.

We compared the procedure time, success rates, complications and recovery times for percutaneous ultrasonic lithotripsy (75 cases) and anatrophic nephrolithotomy (25) in patients with staghorn stones. Although the frequency of retained stone fragments was higher in the former group (13.3 versus 0 per cent), the shorter total procedure time (average 155.1 versus 266.5 minutes), lesser need for blood transfusions (average 2 units packed red cells in 53 per cent of the patients versus 3.5 units in 70 per cent) and narcotics (average 16 versus 33 doses), and far more rapid return to work (average 14.3 versus 54.5 days after the patients were discharged from the hospital) strongly favor percutaneous over open stone removal.

Adult↗
PubMed1986

Percutaneous surgery for ureteropelvic junction obstruction (endopyelotomy): technique and early results.

We incised ureteropelvic junction obstruction in 31 patients with a cold knife direct-vision urethrotome inserted through a percutaneous nephrostomy tract. In 12 patients renal calculi were removed endourologically during the same session. There were no immediate complications and nephrostograms showed adequate drainage in all cases. Of these patients 8 had previously undergone open pyeloplasty without success. The longest followup is almost 2 years. There have been 4 failures and, thus, the success rate is 87.1 per cent.

Adult↗
PubMed1986

Supine flexible cystoscopy.

We attempted cystoscopy with a flexible instrument and ureteral catheter insertion in 152 supine patients. Cystoscopy was successful in 147 patients (97 per cent) and ureteral catheters were inserted in 133 (91 per cent). Examinations with this instrument are tolerated better than those with rigid cystoscopes, which may improve patient compliance with followup examinations. The current drawbacks, namely a smaller field of view, lower visual acuity and, sometimes, inadequate irrigant flow rates, may be reduced or overcome with improvements in instrument design.

Adolescent↗
PubMed1986

Memory for pictures: does an age-related decline exist?

In the present experiments, the effects of varying detail on memory were examined. In Experiment 1, pictorial embellishment was varied by presenting old and young adults with normal photographs, high-contrast photographs, or line drawings, and testing their memory immediately and 4 weeks later. All of the subjects did best with the most elaborate pictures (normal photographs), and old subjects remembered as well as young at the immediate but not at the delayed interval. In Experiment 2, detail was varied by adding background to line drawings of a central object. Subjects of both ages profited from enhanced background detail, and there were no differences in memory as a function of age. Experiment 3 replicated Experiment 2, except that subjects studied the pictures under divided attention conditions. Again, subjects of both age recognized elaborate pictures best, and no significant age differences emerged. The studies suggest that old and young adults profit from visual embellishment and that memory for meaningful pictures remains relatively intact with age.

Adolescent↗
PubMed1986

Acetylcholinesterase activity in regions of the rat brain following a convulsion.

The effects of electroconvulsive shock on the levels of acetylcholinesterase in several brain regions of the rat were studied. Hippocampus, mesencephalon, cortex, and striatum exhibited rapid changes in acetylcholinesterase activity during the first few minutes following the convulsion, whereas brainstem and basal forebrain levels remained unchanged. In both hippocampus and midbrain there was a sustained decrease in activity: the total acetylcholinesterase activity was decreased by up to 40% within 2 min of the convulsion and did not return to control values for another 3 h. Thirty minutes after a flurothyl-induced convulsion there was a similar fall in acetylcholinesterase activity in both these regions, whereas a subconvulsive electric shock produced no change. It is concluded that a convulsion produces significant short-term decreases in acetylcholinesterase activity in areas of the rat brain that are involved in the generation and propagation of seizures, and the question is raised of whether this is related to the increase in seizure threshold that follows a convulsion.

Acetylcholinesterase↗