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F A Wilson

Publications and source records attributed to F A Wilson.

At least 19 recordsLinked to original sources
PubMed2000

Quercetin glucosides are completely hydrolyzed in ileostomy patients before absorption.

Flavonoids, dietary components in vegetables, fruits and beverages, may protect against coronary heart disease, stroke and cancer. However, the bioavailability of these compounds is questionable. A previous study in ileostomy patients of the most abundant flavonoid, quercetin, suggested a 52% absorption of its major dietary forms, monoglucoside (QMG) and diglucoside (QDG), from an onion meal. However, this was based on indirect measurements after acid hydrolysis. Because human intestinal Caco-2 cell monolayers showed minimal absorption of the glucosides, we repeated the study in ileostomy patients, using molecularly specific analytical methodology for the intact glucosides and quercetin. The onion meal had high concentrations of both QMG and QDG with only trace amounts of quercetin. The intake of QMG and QDG in four patients ranged from 10.9 to 51.6 mg. No QMG or QDG was detected in the ileostomy fluid. In contrast, the amounts of the aglycone quercetin were substantial, 2.9-11.3 mg. This corresponded to 19.5-35.2% of total quercetin glucosides ingested, implying absorption of 64.5-80.7%. These findings suggest a different interpretation than that from the previous study, i.e., that both QMG and QDG are efficiently hydrolyzed in the small intestine by beta-glucosidases to quercetin, most of which is then absorbed.

Adult↗
PubMed1997

Areal segregation of face-processing neurons in prefrontal cortex.

A central issue in cognitive neuroscience concerns the functional architecture of the prefrontal cortex and the degree to which it is organized by sensory domain. To examine this issue, multiple areas of the macaque monkey prefrontal cortex were mapped for selective responses to visual stimuli that are prototypical of the brain's object vision pathway-pictorial representations of faces. Prefrontal neurons not only selectively process information related to the identity of faces but, importantly, such neurons are localized to a remarkably restricted area. These findings suggest that the prefrontal cortex is functionally compartmentalized with respect to the nature of its inputs.

Action Potentials↗
PubMed1996

Ontogenic and glucocorticoid-accelerated expression of rat 14 kDa bile acid-binding protein.

BACKGROUND: A 14 kDa protein is a major rat ileal cytosolic bile acid-binding protein (14 kDa I-BABP). This report describes the normal and glucocorticoid-accelerated postnatal expression of 14 kDa I-BABP. METHODS. 14 kDa I-BABP and its mRNA were detected by antiserum and antisense cRNA probe, respectively, in ileum and ovary from 7-, 14-, 21-, 28-, and 35-day-old rats. RESULTS: A positive histochemical reaction with 14 kDa I-BABP antiserum was found in cytosol of ileal enterocytes and ovarian luteal cells at 21 and 35 days of age, respectively. Likewise, Northern blot analysis indicated that the cRNA probe hybridized to a single transcript of 500 bp in total cellular RNA prepared from the ileum of 21-day-old and ovary of 35-day-old rats. Corticosteroid treatment resulted in a histochemical reaction in ileum of 14-day-old animals as compared to the appearance of this reaction in 21-day-old control littermates. Similarly, Northern blot analysis detected the earlier appearance of mRNA levels in corticosteroid-treated animals (11 days vs. 17 days in control animals). CONCLUSIONS: 14 kDa I-BABP and its mRNA are normally expressed in rat ileum at 17 days of postnatal life. 14 kDa I-BABP is expressed considerably later in rat ovary. Corticosteroid treatment results in precocious expression of ileal 14 kDa I-BABP.

Age Factors↗
PubMed1994

Molecular cloning, tissue distribution, and expression of a 14-kDa bile acid-binding protein from rat ileal cytosol.

A cDNA clone encoding the major intestinal cytosolic 14-kDa bile acid-binding protein (14-kDa I-BABP) was isolated from a rat ileal lambda gt22A library following immunoscreening using a monospecific antiserum raised against a 14-kDa polypeptide found in the rat ileal cytosol. One clone of 516 bp encoded a 128-amino acid protein with a predicted molecular mass of 14,544 Da. The deduced amino acid sequence of 14-kDa I-BABP showed 100% homology to rat intestinal 15-kDa protein (I-15P) and 72% homology to porcine 15-kDa gastrotropin, whereas comparison of I-BABP to rat 14-kDa fatty acid-binding proteins of liver, intestine, and heart revealed homologies of 44%, 25%, and 28%, respectively. Northern blot analysis revealed a single transcript of approximately 0.5 kb in ileum and ovary; however, the abundance of I-BABP mRNA was much greater in ileum than in ovary. No transcript was seen in RNA extracted from stomach, jejunum, colon, liver, adrenal, brain, heart, kidney, or testis. Transfection of the I-BABP cDNA into COS-7 cells resulted in the expression of a 14-kDa protein that was identical to the ileal cytosolic I-BABP as determined by immunoblotting. Photoaffinity labeling of expressed 14-kDa protein was saturable with respect to increasing concentrations of 7,7-azo[3H]taurocholate (Km, 83.3 microM; Vmax, 6.7 pmol/mg per 5 min). Taurocholate inhibited 7,7-azotaurocholate labeling by > 96% with lesser inhibition by taurochenodeoxycholate (83.1%), chenodeoxycholate (74.6%), cholate (50.5%), and progesterone (38.5%), whereas oleic acid and estradiol did not inhibit binding.

Amino Acid Sequence↗
PubMed1994

Functional synergism between putative gamma-aminobutyrate-containing neurons and pyramidal neurons in prefrontal cortex.

The responses of putative gamma-aminobutyratergic interneurons (fast-spiking) and pyramidal (regular-spiking) cell pairs were compared in monkeys performing visual and memory-guided oculomotor tasks. Both fast- and regular-spiking neurons had similar receptive fields, indicating that gamma-aminobutyratergic interneurons carry a specific informational signal, as opposed to providing nonspecific modulation. However, the responses of the pairs were inverted and the timing of excitatory and inhibitory responses appeared to be phased, a property consistent with gamma-aminobutyrate-mediated shaping of receptive fields. These observations (i) provide evidence that interneurons and pyramidal cells can be differentiated in vivo and (ii) begin to elucidate the role of gamma-aminobutyratergic mechanisms in cognition.

Action Potentials↗
PubMed1994

Viewing preferences of rhesus monkeys related to memory for complex pictures, colours and faces.

In order to determine the preferences of rhesus monkeys for visual stimuli, their eye movements were measured in response to presentations of complex pictures, fields of uniform colour, and of faces using the scleral search coil technique. The monkeys (n = 4) controlled both the onset and offset of the stimuli by the direction of their gaze. Each stimulus was presented 4 times, with 0 or 2, and 36 or 38 trials between successive presentations. Several trends were apparent in their scanning behaviour: (1) all 4 monkeys spent more time looking at pictures and faces compared to colour fields. As individuals, they differed in their overall propensity in looking at visual stimuli: monkeys that spent the most (or least) time looking at pictures spent the most (or least) time looking at colour fields. (2) Although the monkeys appeared to prefer pictures and faces to colour fields as measured by gaze duration, preferences for individual pictures, faces and colour fields were not evident. (3) Memory for recently presented stimuli substantially affected gaze duration which was significantly longer for the first compared to the second presentation of the pictures and faces, and memory was estimated to influence gaze duration over as many as 38 intervening trials. These effects were not significant in the case of colour fields. (4) There were no significant differences either in the average latencies to initiate eye movements or the number of saccades on the first and second presentations of pictures, colors or faces for the 4 monkeys. However, the average latencies to the first eye movement within a trial were longer for colour fields than for pictures for all 4 monkeys. Individual monkeys differed substantially in their mean latencies for the initiation of the first eye movement within a trial, which ranged from 235 ms to 414 ms in the two extreme cases. (5) At the presentation of faces, the monkeys tended to make saccades to major facial features, and only occasionally to the perimeter of faces. We conclude, firstly, that patterns of eye movements in monkeys reflect their natural predilection for sampling novel stimuli and that monkeys are motivated to view visual arrays. Secondly, that the protracted viewing of novel stimuli and long latencies to initiate saccades contrasts with short latency neuronal responses recorded in inferior temporal cortex. These behavioural and neurophysiological data suggest that neuronal activity specific to novel stimuli and to faces is not a consequence of oculomotor responses to these stimuli.

Animals↗
PubMed1993

Dissociation of object and spatial processing domains in primate prefrontal cortex.

Areas and pathways subserving object and spatial vision are segregated in the visual system. Experiments show that the primate prefrontal cortex is similarly segregated into object and spatial domains. Neurons that code information related to stimulus identity are dissociable, both by function and region, from those that code information related to stimulus location. These findings indicate that the prefrontal cortex contains separate processing mechanisms for remembering "what" and "where" an object is.

Animals↗
PubMed1993

The effects of stimulus novelty and familiarity on neuronal activity in the amygdala of monkeys performing recognition memory tasks.

The function of the amygdala in behavioural responses to novel stimuli and its possible function in recognition memory were investigated by recording the responses of 659 amygdaloid neurons in monkeys performing recognition memory and visual discrimination tasks. The aim was to determine the contribution of the amygdala in the encoding of familiarity and therefore its role in supporting memory-related neuronal mechanisms in the basal forebrain. The responses of three groups of neurons reflected different forms of memory. One group (n = 10) responded maximally to novel stimuli and significantly less so to the same stimuli when they were familiar. The calculated memory spans of these neurons were in the range of 2-10 intervening trials, and this short-term retention of information may reflect the operation of a neural mechanism encoding memory for the recency of stimulus presentation. Two other groups responded to the sight of particular categories of familiar stimuli: to foods (n = 6) or to faces (n = 10). The responses of some of these stimulus-selective neurons declined with repeated presentations of foods (3/4 tests) and faces (2/6 tests). The activity of these latter two groups of neurons may be involved in behavioural responses to familiar visual stimuli, particularly when such stimuli have affective or motivational significance. We conclude that the neurophysiological data provide evidence of amygdaloid mechanisms for the recognition of recently seen visual stimuli. However, these amygdaloid mechanisms do not appear to be sufficient to support the performance of long-term recognition memory tasks without additional and complementary functions carried out by other ventromedial temporal, prefrontal and diencephalic structures which also project to the basal forebrain.

Amygdala↗
PubMed1993

Timed photoaffinity labeling and characterization of bile acid binding and transport proteins in rat ileum.

Rat ileal enterocytes were radiolabeled by flash photolysis with a photolabile derivative of taurocholate (7,7-azo-[3H]TC) and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Maximal labeling of the bile acid binding proteins (BABPs) was achieved between 15 and 90 s. When enterocytes were pulsed with 7,7-azo-[3H]TC for 2 min, and then 0.5 mM TC was added to chase the radiolabel, the radioactivity in the BABPs was displaced by 50% after 2 min. The 99-kDa brush-border membrane (BBM) protein had the highest initial labeling rate, followed by 43-kDa actin, 35- and 14-kDa cytosolic proteins, 54-kDa basolateral membrane (BLM) protein, 59-kDa BLM-associated protein, and 20-kDa microsomal protein. When a mixed microsomal and cytosolic fraction was photolabeled with 7,7-azo-[3H]TC and then separated, the 20-kDa microsomal protein was labeled. However, if the microsomal fraction alone was photolabeled, the 20-kDa protein was not labeled, suggesting this protein required a cytosolic cofactor for labeling. Using Triton X-114 phase separation and EDTA extraction, the BABPs were separated into amphiphilic integral membrane proteins (99- and 54-kDa proteins) and hydrophilic proteins (14-, 35-, 43-, and 59-kDa proteins). From these data, a model is proposed for transcellular bile acid transport in rat ileal enterocytes.

Affinity Labels↗
PubMed1991

Effect of antiserum to a 99 kDa polypeptide on the uptake of taurocholic acid by rat ileal brush border membrane vesicles.

A 99 kDa polypeptide in rat ileal brush border membrane (BBM), regarded as a component of the active bile acid transport system on account of photoaffinity labeling, has been purified by affinity chromatography and preparative gel electrophoresis and utilized as an immunogen for raising polyclonal antibody. Immune serum, but not preimmune serum, specifically recognized a single band of 99 kDa protein on immunoblots of ileal and renal BBM. In contrast, no reactivity was observed with proteins in jejunal BBM. This polyclonal antibody, compared with preimmune serum and anticytosolic bile acid binding protein (14 kDa) serum, significantly inhibited the Na+ dependent uptake of [3H] taurocholate by BBM vesicles (p less than 0.01). [14C] D-glucose uptake by BBM vesicles was not influenced by the immune serum (p less than 0.01). Thus, these studies provide further support for the specific role of a 99 kDa protein in ileal BBM bile acid transport.

Animals↗
PubMed1991

Characterization of a novel 14 kDa bile acid-binding protein from rat ileal cytosol.

A 14 kDa polypeptide in rat ileal cytosol has been identified as the major intestinal cytosolic bile acid-binding protein (I-BABP) by photoaffinity labeling with the radiolabeled 7,7-azo derivative of taurocholate (7,7-azo-TC). To further characterize I-BABP, the protein was purified by lysylglycocholate Sepharose 4B affinity and DE-52 anion-exchange chromatography. The purified I-BABP contained a single 14 kDa band on SDS-PAGE. The 14 kDa protein showed a 26-fold increase in binding affinity for [3H]7,7-azo-TC compared to cytosolic protein. Immunoblotting of protein fractions separated by affinity chromatography showed that neither liver fatty acid binding protein (L-FABP) nor intestinal fatty acid binding protein (I-FABP) bind to the affinity column and that the 14 kDa protein which bound to the column and was subsequently eluted with detergent did not cross-react with anti-L-FABP or anti-I-FABP. The 14 kDa protein labeled with [3H]7,7-azo-TC was radioimmunoprecipitated from cytosol by rabbit antiserum raised against purified I-BABP. I-BABP was shown to have a blocked N-terminus; however, its mixed internal sequence generated from cyanogen bromide-cleaved protein and amino acid composition indicated that it was related to (although clearly distinct from) both I-FABP and L-FABP. These studies have isolated a 14 kDa bile acid-binding protein from rat ileal cytosol which is immunologically and biochemically distinct from I-FABP and L-FABP.

Amino Acid Sequence↗
PubMed1991

Identification of the 14 kDa bile acid transport protein of rat ileal cytosol as gastrotropin.

The 14 kDa bile acid binding protein of rat ileal cytosol (I-BABP), previously shown to be the major intracellular transporter of bile acids in enterocytes, was purified by affinity chromatography and gel electrophoresis. Enzymatic digestion of I-BABP which had been electroblotted to nitrocellulose led to the recovery and sequence analysis of four peptides representing 47 residues of sequence (approximately 35% of the full sequence). All the peptide sequences displayed high levels of identity (greater than 60%) and homology (greater than 80%) to the sequences of porcine and canine gastrotropin. This high level of homology together with other features of I-BABP identify it as rat gastrotropin, establishing gastrotropin as the major intracellular bile acid carrier of rat enterocytes.

Amino Acid Sequence↗
PubMed1991

The effects of visual stimulation and memory on neurons of the hippocampal formation and the neighboring parahippocampal gyrus and inferior temporal cortex of the primate.

The activity of 736 single neurons was recorded from the hippocampal formation (HF), the rhinal cortex (RH), the medial and anterior inferior temporal cortex (TE), or areas TF and TH of the parahippocampal gyrus (PHG) of monkeys during the performance of a delayed matching to sample task. The results indicate differences between the areas in their contributions to sensory processing and memory. Of the neurons, 55% responded to either the first (S1) and/or the second (S2) of the two successively presented visual stimuli. The proportion of responsive neurons and the proportion of neurons that responded selectively on the basis of shape or color (but not size) were significantly higher in areas TE + RH than in HF + PHG. The responses to S1 differed from those to S2 for 18% of the total sample: of these differentially responsive neurons, 66% of the TE + RH neurons responded more strongly to S1 (the sample presentation, allowing stimulus acquisition), whereas 71% of the HF + PHG neurons responded more strongly to S2 (the match/nonmatch comparison, when the behavioral decision could be made). Of 239 TE + RH neurons recorded during the delayed matching task or when objects were shown, 12% displayed evidence of memory for the previous occurrence of stimuli by responding strongly to the first, but significantly less strongly to subsequent presentations of visual stimuli that were novel or had not been seen recently. In contrast, none (0%) of 328 neurons so tested in HF and PHG had a response that declined significantly on stimulus repetition. For six (86%) of seven TE + RH neurons tested, the decrement in response persisted even after distraction by intervening presentations of other stimuli. Further evidence of information storage was found for 7 (33%) of 21 neurons for which responses to the first presentations of unfamiliar objects were significantly greater than to the first presentations of very familiar objects, even though the familiar objects had not been seen for greater than 15 min.

Animals↗
PubMed1990

Hippocampus and medial temporal cortex: neuronal activity related to behavioural responses during the performance of memory tasks by primates.

Neuronal activity was recorded in the hippocampal formation, the parahippocampal gyrus and medial inferotemporal cortex of monkeys performing memory tasks. In a modified delayed matching to sample task in which 2 sequentially presented stimuli were compared on each trial, a match condition required a right panel press, whereas a non-match condition required a left panel press. The activity of 336/736 (45.7%) neurons was related to the behavioural responses (left or right panel presses) in this task. The incidence of response-related activity was 57.4% in cortical areas adjacent to the rhinal sulcus plus medial inferotemporal cortex, and 40.2% for the hippocampal formation. For 58.9% of these response-related neurons, the activity change associated with the behavioural response was greater than that during presentation of the sensory stimuli, though neurons commonly responded (33.2% of all recorded neurons) to both sensory and motor events. The activity of 198 neurons (26.9%) differed between go-left and go-right trials; such neurons were found in all areas but were nearly twice as common in the posterior as in the anterior hippocampal formation. The importance of visual stimuli for the response-related neuronal activity was examined during the performance of a delayed alternation task without visual cues indicating direction of response. The response-related activity of 8 neurons recorded during the delayed alternation and the delayed matching tasks was similar in both tasks, indicating that memory for the behavioural responses influences the activity of the response-related neurons. In order to test the effects of stimulus familiarity and non-spatial responses on medial temporal neurons, recognition memory and visual discrimination tasks requiring lick responses were performed. The activity of 2/375 (0.5%) neurons was related to the lick responses; 3/68 neurons in the inferomedial temporal cortex responded on the basis of stimulus novelty and none reflected their reinforcement value. It is concluded that the hippocampal formation, the parahippocampal gyrus and medial inferotemporal cortex all have a role in the utilisation of sensory, mnemonic and motor information underlying the selection of spatially-directed behavioural responses.

Animals↗
PubMed1990

Identification of cytosolic and microsomal bile acid-binding proteins in rat ileal enterocytes.

Studies were performed to determine the subcellular fractions and proteins involved in the intracellular transport of bile acids in rat ileal cells. The photolabile derivative 7,7-azo-taurocholate inhibited the Na(+)-dependent uptake of taurocholate into rat ileal enterocytes reversibly in the dark and irreversibly following photolysis. When photolabeled cells were submitted to subcellular fractionation, greatest radioactivity was found in the soluble protein (SP) fraction with decreasing radioactivity in the brush-border-(BBM), basolateral-(BLM), mitochondria-(MT), microsome-(MC), and Golgi-(GO) enriched fractions. Following trichloroacetic acid precipitation, delipidation, and correction for loss of marker enzyme activity, protein bound radioactivity was in SP greater than BBM greater than MC greater than BLM greater than GO greater than MT. When photolabeled cells were first fractionated and then submitted to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a 99-kDa polypeptide was associated with BBM, 54- and 59-kDa polypeptides with BLM, 14-, 35-, 43-, 59-, and 68-kDa polypeptides with SP and a 20-kDa polypeptide with MC fractions. Immunoprecipitation with known antisera identified the 68-kDa polypeptide as albumin and the 43-kDa polypeptide as actin. No precipitation on the 14-kDa polypeptide was noted with anti-hepatic and anti-intestinal fatty acid-binding proteins. No precipitation of the 35-kDa polypeptide occurred with antibody to the hepatic cytosolic bile acid-binding protein. These studies reveal a previously unrecognized 20-kDa microsomal, and 14- and 35-kDa cytosolic bile acid-binding polypeptides which may be involved in the transcellular movement of bile acids.

Animals↗
PubMed1990

Modern approaches to bile acid transport proteins.

New techniques for studying solute uptake across epithelial membranes in the gut are providing a clearer picture of bile acid handling. In the small intestine, liver, and other sites, membrane proteins that mediate active bile acid transport are key players. Better understanding of these transporters may lead to elucidation of disorders of bile handling and better treatment of such disorders.

Affinity Labels↗