Biomedical subjects

G V Jones

Publications and source records attributed to G V Jones.

At least 19 recordsLinked to original sources

PubMed2006

Extreme heat reduces and shifts United States premium wine production in the 21st century.

Premium wine production is limited to regions climatically conducive to growing grapes with balanced composition and varietal typicity. Three central climatic conditions are required: (i) adequate heat accumulation; (ii) low risk of severe frost damage; and (iii) the absence of extreme heat. Although wine production is possible in an extensive climatic range, the highest-quality wines require a delicate balance among these three conditions. Although historical and projected average temperature changes are known to influence global wine quality, the potential future response of wine-producing regions to spatially heterogeneous changes in extreme events is largely unknown. Here, by using a high-resolution regional climate model forced by the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios A2 greenhouse gas emission scenario, we estimate that potential premium winegrape production area in the conterminous United States could decline by up to 81% by the late 21st century. While increases in heat accumulation will shift wine production to warmer climate varieties and/or lower-quality wines, and frost constraints will be reduced, increases in the frequency of extreme hot days (>35 degrees C) in the growing season are projected to eliminate winegrape production in many areas of the United States. Furthermore, grape and wine production will likely be restricted to a narrow West Coast region and the Northwest and Northeast, areas currently facing challenges related to excess moisture. Our results not only imply large changes for the premium wine industry, but also highlight the importance of incorporating fine-scale processes and extreme events in climate-change impact studies.

Agriculture↗

PubMed2001

Immuno-characterisation of neuroendocrine cells of the rat thymus gland in vitro and in vivo.

Primary cell cultures and organ fragments of rat thymus were characterised by use of a panel of antibodies raised against the neural adhesion molecule L1, tyrosine hydroxylase, protein gene product 9.5, nerve growth factor, calcitonin gene-related peptide, glial fibrillary acidic protein, vimentin, pan-cytokeratin, a ganglioside of neural crest and neuroendocrine cells (A2B5), and thymulin (4 beta). Immunoreactivity for neural markers only was identified in a single morphology (nerve-like) of cell in culture and throughout the adult thymus as fine, tortuous staining. Immunoreactivity for endocrine markers only was identified in polygonal epithelial-like cells in culture, throughout viable tissue in fragment culture and in the subcapsular cortex of the adult thymus. Immunoreactivity for both endocrine and neural markers was identified in three distinct morphologies in cell culture: elongate, spherical, and stellate. Similar results were observed in the mitotic periphery of the cultured fragments and in the medulla and cortico-medullary junction of the adult thymus. Cells with immunoreactivity to A2B5 were present in primary and fragment cultures and occurred throughout the adult thymus. The apparent diversity of cell immunoreactivity in primary and fragment thymic cultures suggests that numerous neural and endocrine factors may be required for the development and/or regeneration of the thymic microenvironment.

Animals↗

PubMed2001

Searching for two things at once: evidence of exclusivity in semantic and autobiographical memory retrieval.

We examined whether retrieval from semantic memory (Experiment 1) and autobiographical memory (Experiment 2) is exclusive, or whether people can search for two things at once. In Experiment 1, participants retrieved items as quickly as possible over 4 ruin from single categories (e.g., foods, countries) and from disjunctive categories (e.g., foods or countries). In Experiment 2, participants retrieved autobiographical episodes associated with single cue words (e.g., flower, ticket) or with disjunctive cue words (e.g., flower or ticket). In both experiments, retrieval of items from the disjunctive category did not exceed predictions based on optimal sequencing of retrieval from the corresponding two single categories. That is, exclusivity was observed to occur in retrieval from among multiple nonoverlapping categories in both semantic and autobiographical memory.

Adolescent↗

PubMed2000

A note on Corballis (1997) and the genetics and evolution of handedness: developing a unified distributional model from the sex-chromosomes gene hypothesis.

A unified, quantitative model for sex, twin, parent, and grandparent influences on handedness is presented. Recent research modeling the evolutionary development of genetic mechanisms for the transmission of handedness on the basis of genotype fitness has appeared to lead to the conclusion that a handedness gene cannot be located on the sex chromosomes. It is shown in this article, however, that this conclusion is not of general validity. The sex-chromosomes hypothesis is developed further, and it is demonstrated that a wide-ranging, detailed, and parsimonious account of the distribution of handedness is obtained when left-handedness is assumed to be associated recessively, and with low penetrance, with genetic variation located on the X chromosome.

Female↗

PubMed1999

Handedness and season of birth: a gender-invariant relation.

In an earlier study, Dellatolas, Curt and Lellouch (1991) concluded that handedness is not related to season of birth. However, post-hoc exploration of their and other sets of data has shown that there is an apparent tendency for left-handedness to be more prevalent in the period March-July than in the period August-February. The present work tested this seasonal hypothesis prospectively among university students. It was found that the proportion of all left-handed participants who were born in the period March-July was indeed significantly greater than the proportion of all right-handed participants who were born in the same period. Furthermore, the pattern of seasonal influence upon handedness did not vary significantly between females and males. The relation between handedness and season of birth may be linked to seasonal variation in other factors such as the incidence of infectious agents.

Adolescent↗

PubMed1999

Expression of parathyroid hormone-related protein and the parathyroid hormone/parathyroid hormone-related protein receptor in rat thymic epithelial cells.

Thymic epithelial cells are an important source of cytokines and other regulatory peptides which guide thymocyte proliferation and maturation. Parathyroid hormone-related protein (PTHrP), a cytokine-like peptide, has been reported to affect the proliferation of lymphocytes in vitro. The studies presented here were undertaken to test the hypotheses that PTHrP is produced locally within the thymus where it could influence thymocyte maturation and, more specifically, that thymic epithelial cells (TEC) could be the intrathymic source of PTHrP expression. To this end, immunohistochemical studies were performed to localise PTHrP and the PTH/PTHrP receptor within the adult rat thymus. Antibodies directed against 2 different PTHrP epitopes, PTHrP(1-34) and PTHrP(34-53), demonstrated prominent specific PTHrP immunoreactivity in both subcapsular and medullary TEC. In addition, faint but specific staining for PTHrP was seen in the cortex, interdigitating between cortical lymphocytes while sparing epithelial-free subcapsular areas, thus suggesting that cortical TEC could also be a source of PTHrP immunoreactivity. In contrast, PTH/PTHrP receptor immunoreactivity was only seen in medullary and occasional septal TEC; no evidence of cortical or lymphocytic PTH/PTHrP receptor immunoreactivity was detected. Immunohistochemical studies of cultured cytokeratin-positive rat TEC confirmed the results of these in situ studies as cultured TEC were immunoreactive both for PTHrP and the PTH/PTHrP receptor. Thus these results demonstrate that PTHrP is produced by the epithelial cells of the mature rat thymus. This suggests that PTHrP, a peptide with known cytokine, growth factor and neuroendocrine actions, could exert important intrathymic effects mediated by direct interactions with TEC, or indirect effects on PTH/PTHrP receptor-negative thymocytes.

Animals↗

PubMed1998

Immunoreactivity of neural crest-derived cells in thymic tissue developing under the rat kidney capsule.

In order to study the functional development of a thymus in an experimental model, small pieces of adult rat thymic tissue were cultured for 9 days and implanted under the kidney capsule of littermates. The tissues were examined with a panel of antibodies raised against thymic and neural factors and neural crest cells at intervals from 5 to 13 days. At 5 days post-implantation, there were groups of L1+ cells within the implants that reacted with antibodies raised against neural and neural crest cell markers. L1+ cells were highly mitotic, rounded cells measuring 8.7 +/- 0.6 micrometer in diameter. Double immunostaining with different combinations of antibodies showed that 94% of the L1+ cells were also TH+, and many were HNK-1/NCAM+, PGP 9.5+, NGF+, chromogranin A+, VIP+, S100+, CGRP+, GAD+, and A2B5+. A few were also pan-cytokeratin+. These results indicate that these cells are derived from neural crest derived cells and belong to the neuroepithelial line of development. The L1+ cells were most numerous before nerves appeared (about Day 9) and reduced in number and extent as the thymus differentiated. The neural crest cells occasionally had long cytoplasmic extensions, but it was not possible to decide if they formed the nerves that appeared in the implants. Adult thymuses also contained a population of L1+ and HNK-1/NCAM+ cells, mainly in the subcapsular cortex, the septa, and the medulla. These cells could be a source of neural crest cells able to repopulate the implant. The adult thymus may always contain a reservoir of cells potentially capable of producing neuropeptides and transmitter factors required for thymic growth and regeneration.

Age Factors↗

PubMed1998

Generalizing everyday memory: signs and handedness.

Memory for frequently encountered road signs was investigated. In Experiment 1, the average level of recall of road sign features was found to be only 47%. In Experiment 2, more left-handed than right-handed people recalled that a walking figure faces right on one sign, whereas more right-handed than left-handed people recalled that a digging figure faces left on another sign. Performance thus reflected not a difference in level of mnemonic ability between left-handed and right-handed groups but instead the compatibility between group and task. In Experiment 3, participants were asked to draw any figure walking and any figure digging, with a pattern of results similar to that of Experiment 2. It is suggested that handedness effects in recall are mediated by motor imagery.

Adolescent↗

PubMed1997

Aspects of calcium transport by the ovine placenta: studies based on the interplacentomal region of the chorion.

An in vitro technique for the measurement of calcium uptake into the maternal-facing fetal chorionic membrane (apical trophoblast) was used to study the relationship between calcium uptake and stage of pregnancy in the sheep. The effects on calcium uptake of varying calcium concentration and temperature of the incubation medium, of adding calcium channel blockers or heavy metals (lanthanum and nickel) or calcium ionophore/agonist were also studied. The data indicate a saturable calcium uptake process, plateauing after 15 min incubation. This uptake remained constant throughout the last third of gestation until a significant fall in uptake was noted during the final week prior to parturition. This uptake was not due to extracellular cellular diffusion since there was no significant uptake of tritiated inulin over the same period in each case. Calcium uptake in this system was also shown to be a temperature dependent process which was abolished at temperatures of 0-4 degrees C. A decrease in calcium concentration to 0.12 mM in the incubation medium also caused a corresponding decrease in calcium uptake to 21 per cent of control (1.2 mM). The addition of the heavy metals lanthanum and nickel also significantly reduced calcium uptake as did the calcium channel blockers verapamil, metoprolol and diltiazem. The calcium channel ionophore A23187 increased calcium uptake into the material facing chorion. Although the interplacentomal chorion may not be representative of the whole of the placental unit, it clearly contains a specific calcium uptake process under local physiological control. The blocking of calcium uptake by the specific I-type calcium channel blocker verapamil may indicate the presence of I-type channels of unusually low sensitivity since the concentration needed to block them was much higher than would be required for excitable I-type channels in isolated cells.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1997

Handedness dependency in recall from everyday memory.

A number of previous studies have demonstrated systematic misremembering of the direction in which the Queen's head faces on British coins. Two experiments were carried out to investigate whether this phenomenon is affected by a person's handedness. In both experiments, right-handed and left-handed participants were found to differ significantly in their verbal responses, with recall performance significantly worse than chance for right-handed but not for left-handed participants. Experiment 2 also examined degrees of handedness, and found significant variation in recall across the handedness range. Performance in this everyday-memory paradigm appears to be determined by both handedness and schema factors. It is proposed that although in this task the response was verbal one, relevant motor imagery may nevertheless have been activated and led to the highly unusual observation of an effect of handedness upon cognitive performance.

Adult↗

PubMed1996

Calcium transport and the localisation of calbindin-D9k in the ruminant placenta during the second half of pregnancy.

In late pregnancy the sheep fetus requires 3 g of calcium per day, all of which must be transported across the trophoblast epithelium of the placenta. Such high levels of calcium transport across other epithelia are normally associated with the presence of calbindin-D9 or -28k. Our immunocytochemical results show that ovine, bovine and caprine interplacentomal trophoblast have high levels of calbindin-D9k, about eight to ten times more than in the placentomal region. The protein is detectable only in the uninucleate trophoblast cells in sheep and goat, the frequent binucleate cells show none. The calbindin-D9k is also present in the maternal glandular epithelium but not the surface epithelium of the uterus. The cellular distribution of the calbindin-D9k immunoreactivity suggests a soluble protein homogenously distributed through cytosol and nucleoplasm but absent from all organelles and intercellular spaces. In contrast, the uterine milk protein(s) are localised in Golgi cisternae and secretory vesicles in gland cells and in apical small endocytic vesicles and lysosomes in the uninucleate trophectodermal cells. The distribution of calbindin-D9k supports the concept that it mediates the high calcium flux by facilitated diffusion and not via any vesicular, membrane-bounded system.

Animals↗

PubMed1995

Danegeld remembered: taxing further the coin head illusion.

Two experiments studied memory for the appearance of a Danish 20 kroner coin. The coin bears the portrait of Queen Margrethe II in profile, facing to the right. Previous studies have examined memory for British coins, which similarly bear a right-facing portrait of Queen Elizabeth II. They have revealed the occurrence of a mnemonic illusion, in that British people tend to believe the portrait faces left. This finding has been attributed to the occurrence of a joint coin-stamp schema. British stamps bear a left-facing profile of the Queen, and it is possible that information from the stamp predominates in the formation of the schema. In the case of Denmark, however, stamps bear a full-face portrait of the Queen. Nevertheless, the present experiments showed that the Coin Head Illusion is also found in Denmark. That is, the number of participants recalling the Queen's head as facing to the right was significantly below even the chance level of 50%. Further, this result occurred both for residents of Denmark and for visitors to Denmark. These findings suggest that the bias underlying the Coin Head Illusion may be a more general one than that envisaged by the joint coin-stamp schema hypothesis.

Adult↗

PubMed1995

Integral bias in the cognitive processing of emotionally linked pictures.

It is well established that human cognitive processes are subject to systematic biases associated with particular emotional states. But how do these cognitive biases arise? This question was addressed by means of a pictorial Stroop task which allowed the development of such a bias to be assessed. In each of two experiments, spider-phobic participants were significantly impaired at naming the colours of phobia-related pictures relative to those of control pictures. Investigation of the magnitude of this effect for participants of different ages allowed two contrasting hypotheses concerning the development of such biases to be compared. The integral bias hypothesis asserts that the effects of emotion on cognition reflect integral links between emotional states and cognitive mechanisms, links that are not arbitrary but instead are fixed constituents of our mental architecture. In contrast, the inferred bias hypothesis asserts that these effects arise as a consequence of the gradual establishment of associations between particular emotional states and particular patterns of cognitive behaviour. It was found that the magnitude of the observed bias remained approximately constant irrespective either of the ages of participants or of the directly estimated durations of their phobias. This fixed relation provides strong support for the integral bias explanation of the cognitive effects of an emotional disturbance. Finally, the evolutionary context in which integral links between emotion and cognition may arise is discussed.

Adolescent↗

PubMed1994

No selective deficit in recall in amnesia.

Are amnesic patients selectively impaired in recall relative to recognition? Experiment 1 studied a group of Korsakoff amnesics and matched the amnesic level of recognition with that of control subjects by testing control recognition of unrelated words after longer delays. It was found that under these conditions the observed levels of recall were also approximately equal. In Experiment 2, a similar result occurred when the Korsakoff amnesic level of recognition for unrelated words was matched by varying the number of presentations as well as delay before testing. In Experiment 3, a similar result occurred again with a group of amnesics of mixed aetiology and recognition levels for related words matched by varying the duration of presentation and delay before testing. In this experiment, both recognition and recall of the same items were assessed. It was found that for the amnesic group the observed level of dependency between recognition and recall was less than that for the control group. One possible interpretation of this result is that the microstructure of the recall process may be selectively disturbed in amnesia. The principal finding, however, is that in all three experiments there was no significant evidence of the existence in amnesia of a selective deficit in the overall level of recall relative to that of recognition.

Adult↗

PubMed1993

Spatial memory in amnesia: evidence from Korsakoff patients.

Two experiments are reported which investigated a hypothesised disproportionate deficit in amnesic spatial memory. Korsakoff amnesic memory for the locations of objects or words placed on a grid was compared to control memory which had been attenuated by longer delays before testing. The effects of incidental versus intentional encoding of the locations were compared. No significant evidence of a disproportionate spatial memory deficit in Korsakoff amnesia was found, intentional instructions did not improve Korsakoff amnesic spatial memory scores, and there was no significant evidence of a trade-off of item memory and location memory specific to the Korsakoff amnesic group. Rather, intentional instructions significantly reduced item memory in both Korsakoff amnesics and normal controls, while having no effect on spatial memory. When location was scored by lenient criteria, there was no significant difference between groups for this measure, nor for recall and recognition memory for these items. Thus Korsakoff amnesic memory was very similar to that of control memory attenuated by longer delays before testing. The Korsakoff amnesic subjects' memory therefore differed quantitatively rather than qualitatively from that of control subjects' memory.

Adult↗

PubMed1993

Reversible vasopressin deficiency in severe hypernatremia.

Studies to assess the relationship between plasma arginine vasopressin concentration (Pavp) and plasma osmolality (Posm) were performed on an elderly patient with dementia who developed severe hypernatremia due to inadequate water intake following a debilitating hip fracture. Serum sodium concentrations were 174 and 196 mEq/L on two consecutive hospital admissions. During the second of these admissions, sequential measurements of Pavp and Posm were obtained as hypernatremia was gradually corrected. Pavp during this period was correlated with Posm (r = 0.887, P < 0.01), but was low despite the presence of hyperosmolality and volume depletion. Pavp decreased from 0.56 microU/mL to 0.18 microU/mL as Posm decreased from 396 to 338 mOsm/kg H2O. The regression line of this relationship intercepted the abscissa at 320 mOsm/kg H2O. Hypertonic sodium chloride infusion to reassess this relationship 2 days following the correction of hypernatremia increased Pavp only to 0.67 microU/mL while increasing Posm from 297 to 316 mOsm/kg H2O. Nevertheless, Pavp and Posm were significantly correlated (r = 0.937, P < 0.001). The slope of the regression line was 0.031, and Posm at the abscissal intercept was 292 mOsm/kg H2O. A similar increase in Posm from 290 to 310 mOsm/kg H2O during hypertonic sodium chloride infusion 11 days following the correction of hypernatremia increased Pavp to 1.95 microU/mL (r = 0.786, P < 0.05). The magnitude of the increase in Pavp at this time was equivalent to that previously observed in studies of normal subjects. The slope (0.048) and abscissal intercept (280 mOsm/kg H2O) of linear regression were also consistent with observations in studies of normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1993

A protoconnectionist theory of memory.

I.A. Richards published a chapter entitled "Memory" in 1924 in which he proposed what may be viewed as the outline of a connectionist theory of memory. However, this protoconnectionist theory attracted no subsequent attention. There appear to be two types of reason for this neglect. The first concerns the impossibility at that time of implementing the theory in the form of an explicit model. The second concerns the nature of Richard's career. On the one hand, Richards did not himself subsequently develop his theory of memory any further. On the other, the fact that Richards was not generally perceived as a psychologist probably impeded the dissemination of his theory among psychologists. The neglect of Richards's theory demonstrates the range of factors, other than the strictly scientific, which can be important in determining the influence or otherwise of a psychological theory.

History, 19th Century↗

PubMed1992

Modulation of plasma aldosterone by physiological changes in hydrogen ion concentration.

To assess the effect of extracellular hydrogen ion concentration (PH+) on aldosterone secretion, studies in which other known modulators could be controlled were performed on 13 patients undergoing hemodialysis. High (35 mM) or low (14-17 mM) dialysate bicarbonate concentrations were utilized on separate days to either decrease or increase PH+, while plasma potassium concentrations (PK) were held at constant levels and changes in plasma renin activity (PRA) were minimized by avoiding changes in body weight. Changes in PH+ were associated with concordant changes in plasma aldosterone concentration (Pa) in both high- and low-bicarbonate studies. When these changes in Pa in high- and low-bicarbonate studies were analyzed together as a function of corresponding changes in PH+, a significant correlation could be demonstrated (r = 0.659, P less than 0.001). There was no correlation between changes in Pa and changes in PK, plasma sodium, plasma adrenocorticotropic hormone (ACTH), or PRA. Using the same methods to control PH+ and other variables during hemodialysis, the effects of altered PH+ on ACTH-stimulated aldosterone and cortisol secretion were evaluated in studies on six patients who received incremental infusions of ACTH after pretreatment with dexamethasone. In these studies, there was no demonstrable effect of PH+ on Pa or plasma cortisol concentration. We conclude that physiological changes in PH+ have a weak modulating effect on basal aldosterone secretion that may not be evident in the presence of other acutely applied stimuli.

Adrenocorticotropic Hormone↗