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Biomedical subjects

A M Williams

Publications and source records attributed to A M Williams.

At least 37 records · Page 2Linked to original sources
PubMed2000

Perceptual skill in soccer: implications for talent identification and development.

In this review, key components of perceptual skill in soccer are identified and implications for talent identification and development highlighted. Skilled soccer players can recall and recognize patterns of play more effectively than their less skilled counterparts. This ability to encode, retrieve and recognize sport-specific information is due to complex and discriminating long-term memory structures and is crucial to anticipation in soccer. Similarly, experts use their knowledge of situational probabilities (i.e. expectations) to anticipate future events. They have a better than average idea of what is likely to happen given a particular set of circumstances. Also, proficiency-related differences in visual search strategy are observed. Skilled players use their superior knowledge to control the eye movement patterns necessary for seeking and picking up important sources of information. The nature of the task plays an important role in constraining the type of search used. Skilled soccer players use different search strategies when viewing the whole field (i.e. 11 vs 11 situations) compared with micro-states of the game (i.e. 1 vs 1, 3 vs 3 situations). Visual search behaviour also differs between defensive and offensive plays. These observations have implications for the development of perceptual training programmes and the identification of potential elite soccer players.

Attention↗
PubMed2000

Distress and hardiness: a comparison of African-American and white caregivers.

The difficulties and burdens of family caregiving, including mental and physical distress, have been well delineated, especially among White populations. Researchers have suggested that buffers for stress associated with caregiving might include hardiness, social support, or cultural group membership, with African-American caregivers perceiving less stress. This paper reports mental and physical distress and family hardiness among 46 African-American and White caregivers of stroke survivors. In contrast to other reports, African-American and White caregivers in this sample were found to be similar on most demographic measures, estimates of caregiver health, estimates of distress, and estimates of hardiness. The single estimate which showed interethnic difference was the confidence sub-scale of the Family Hardiness Index, on which African-Americans scored lower. This sub-scale is believed to estimate confidence in ability to cope with life's problems.

Adaptation, Psychological↗
PubMed1999

Intravenous administration of ONYX-015, a selectively replicating adenovirus, induces antitumoral efficacy.

Replication-incompetent viral vectors are being developed for the gene therapy of cancer. Although some of these may eventually be proven to have significant localized antitumoral activity, none to date have been shown to infect and cause regression of established tumors following i.v. administration. Because cancer is a systemic disease in almost all fatal cases, the lack of i.v. efficacy is a major limitation to treatment with replication-incompetent viral vectors. ONYX-015 (d11520) is an attenuated adenovirus that replicates in and causes selective lysis of cancer cells. We carried out i.v. efficacy and distribution studies in nude mice with s.c. and intraparenchymal tumor xenografts. ONYX-015 infected and replicated efficiently within tumors following i.v. administration. Viral titers in livers were relatively high 3 h after administration but decreased rapidly, becoming undetectable after 24 h. Effective antitumor doses were not associated with hepatic toxicity. Viral replication within tumors was associated with regressions in several tumor models. Selectively replicating viruses like ONYX-015 hold promise as agents to treat metastatic cancer.

Adenoviridae↗
PubMed1999

Tumour necrosis factor-alpha (TNF-alpha) transcription and translation in the CD4+ T cell-transplanted scid mouse model of colitis.

The adoptive transfer of activated CD4+ alpha/beta T cell blasts from the spleens of immunocompetent C.B-17+/+ or BALB/cdm2 mice into C.B-17scid/scid (scid) mice induces a colitis in the scid recipient within 8 weeks, which progresses to severe disease within 16 weeks. T cells isolated from recipient colon show a Th1 cytokine phenotype. We have examined the relationship between the phenotype of the cellular infiltrate and the transcription and translation of the proinflammatory cytokine TNF-alpha. The techniques of double indirect immunohistology and in situ hybridization using digoxigenin-labelled riboprobes were used. The prominent myeloid cell infiltrate in diseased tissues comprised F4/80+, Mac-l+ macrophages, neutrophils, dendritic cells and activated macrophages. TNF-alpha transcription and translation were associated with activated macrophages in the lamina propria. Activated macrophages transcribing and translating TNF-alpha were clustered in areas of tissue destruction. Crypt epithelium of inflamed tissues transcribed TNF-alpha at a very early stage of the disease process, but translation of TNF-alpha protein could only be found in advanced epithelial dysplasia. This indicates differential post-transcriptional control of TNF-alpha in activated macrophages and the epithelium.

Adoptive Transfer↗
PubMed1999

The role of the response-reinforcer relation in delay-of-reinforcement effects.

The role of the response-reinforcer relation in maintaining operant behavior under conditions of delayed reinforcement was investigated by using a two-operandum (i.e., two-key) procedure with pigeons. Responding on one key was reinforced under a tandem variable-interval differential-reinforcement-of-other-behavior (tandem VI DRO) schedule. The schedule defined a resetting unsignaled delay-of-reinforcement procedure in that a response was required when the interfood interval of the VI schedule lapsed, but further responding during the DRO component on either key reset the time interval. This ensured a fixed delay duration between any response and reinforcement. Responding on another key, physically identical to the first one except for spatial location, otherwise was without consequence. The location of the key correlated with the delay-of-reinforcement procedure varied between sessions according to a semirandom sequence. Differences in response rates between the two keys were greater, with proportionally higher rates on the key correlated with the delay-of-reinforcement procedure, the longer the delay-of-reinforcement procedure remained correlated with the same key. Differences in responding on the two keys also increased within individual sessions. These results suggest that the response-reinforcer relation is the primary determinant of responding when responding is acquired and maintained with delayed reinforcement.

Animals↗
PubMed1999

A national survey of current admission practices in selected allied health educational programs.

This study investigated the admission practices of selected allied health programs, specifically considering the priorities placed on cognitive and noncognitive factors. The extents to which diversity and a student's desire to work in underserved areas are considered in the selection process were also examined. Of 206 questionnaires mailed to accredited baccalaureate occupational therapy, physical therapy, health information management, and respiratory therapy programs, 144 were returned. The results indicate that allied health programs use combinations of cognitive and noncognitive factors in selecting students for admission. A higher priority is placed on overall grade-point average (GPA) and GPA in foundation courses, whereas lower priorities are placed on the need for diversity and a student's desire to work in underserved areas. The authors discuss the implications of the findings and urge the rethinking of the traditional selection method, which places applicants from ethnic/racial minority backgrounds at a disadvantage.

Adolescent↗
PubMed1999

Health risks of health care workers: health risks appraisal results from the newly independent country of Georgia.

Health promotion and disease prevention activities should be carried out by all health care professionals. These activities are especially important in the Newly Independent States (NIS) of the former Soviet Union where resources are not available to meet all health care needs. Little is known about actual health risks among health care professionals in the NIS. Such self knowledge is important to link professional's prevention activities to risk factors for disease. To determine the prevalence of selected health risks of health professionals in Tbilisi, the capital of the NIS Georgia, a survey was conducted in 1996 with a convenience sample of 107 physicians and nurses. Participants completed the Healthier People Health Risk Appraisal (HPHRA), then researchers measured each subject's height, weight, blood pressure, and total cholesterol. Compared to the U.S. norms used in the HPHRA program analysis, measured group results for the Georgians were in the very high risk category for lack of seatbelt usage and stressful lifestyle, in the high risk category for lack of exercise, and in the moderately high risk category for blood pressure and smoking. The measured weight and reported alcohol consumption for Georgians was comparable to the U.S. national averages and total cholesterol values were below U.S. average levels.

Adult↗
PubMed1998

Three-step purification of lipopolysaccharide-free, polyhistidine-tagged recombinant antigens of Mycobacterium tuberculosis.

Previous work has shown that the study of host immune responses against Mycobacterium tuberculosis, the causative agent of tuberculosis, requires the availability of multiple mycobacterial antigens. Since purification of protein from M. tuberculosis cells is extremely cumbersome, we developed a protocol for purifying milligram amounts of ten recombinant antigens of M. tuberculosis from E. coli cells. Purified proteins were immunologically active and free of contaminants that confound interpretation of cell-based immunological assays. The method utilizes a three-step purification protocol consisting of immobilized metal-chelate affinity chromatography, size exclusion chromatography and anion-exchange chromatography. The first two chromatographic steps yielded recombinant protein free of protein contaminants, while the third step (anion-exchange chromatography) efficiently removed E. coli lipopolysaccharide, a potent polyclonal activator of lymphoid cells. The recombinant proteins were immunologically indistinguishable from their native (i.e., purified from M. tuberculosis) counterparts. Thus the method provides a way to utilize recombinant proteins for immunological analyses that require highly purified antigens.

Animals↗
PubMed1998

"An empire lost but a province gained": a cohort analysis of British international retirement in the Algarve.

"The growth of international retirement in the Algarve has coincided with a number of changes in the international framework for population mobility as well as in the nature of the Algarve [Portugal] as a destination area. Tourism development, which is intimately linked to subsequent retirement migration, is particularly important in this. This paper considers the nature of the link between cycles of migration and of development in recipient areas, in the context of the remarkable and relatively late development of the Algarve as an area of tourism and retirement.... Cohort analysis...provides the basis for an examination of changes over time in the socio-demographic profiles of the migrants, their motivations, their residential patterns and their integration."

Acculturation↗
PubMed1998

International retirement migration in Europe.

"This paper presents a review and prospectus of international retirement migration (IRM), dealing mainly with European evidence but also referring to some analogous trends in North America. The paper is in three main parts. It first makes the case for regarding IRM as a significant aspect of population geography and of migration studies; in certain areas of Mediterranean Europe, IRM also has effects on regional economic geography. The second section of the paper discusses some of the early findings from a comparative study of British elderly residents in Tuscany, Malta, the Costa del Sol and the Algarve.... The final part of the article offers further reflections on why IRM is important--for the individual migrants themselves, for the host communities, and for public policy."

Adult↗
PubMed1998

The delivery of quality nursing care: a grounded theory study of the nurse's perspective.

This grounded theory study explored and described the delivery of quality nursing care from the perspective of nurses. Data were gathered by tape recorded interviews, published literature and some participant observation. Ten registered nurses from an acute-care public hospital located in Perth, Western Australia were interviewed. Twelve additional transcripts from interviews conducted by postgraduate students were also used. Quality nursing care was perceived to relate to the degree to which patients' physical, psychosocial, and extra care needs were met. The consequences of quality care were interpreted as 'therapeutic effectiveness', where the therapy provided by nurses was perceived to positively affect patients' healing. This was gauged by the patient's psychosocial and physical response to illness, safety, and satisfaction. Therapeutic effectiveness was facilitated by the development of positive relationships between nurses and patients, nurse's positive attributes and competent practices, as well as a functional nursing team. The problem of nurses' inability to consistently provide quality nursing care to all patients was identified. Insufficient time (caused by a lack of human and physical resources) was perceived as the main reason for this. Dissatisfaction and stress in nurses was related to this problem. To deal with this, nurses used a process named 'selective focusing'. Work was planned to most effectively utilize the time available, within the parameters of safety. Implications for nursing practice, education and management are discussed, and directions for further research are provided.

Adult↗
PubMed1998

Visual search strategy, selective attention, and expertise in soccer.

This research examined the relationship between visual search strategy, selective attention, and expertise in soccer. Experienced (n = 12) and less experienced (n = 12) soccer players moved in response to filmed offensive sequences. Experiment 1 examined differences in search strategy between the two groups, using an eye movement registration system. Experienced players demonstrated superior anticipation in 3-on-3 and 1-on-1 soccer simulations. There were no differences in search strategy in 3-on-3 situations. In 1-on-1 simulations, the experienced players had a higher search rate, involving more fixations of shorter duration, and fixated for longer on the hip region, indicating that this area was important in anticipating an opponent's movements. Experiment 2 examined the relationship between visual fixation and selective attention, using a spatial occlusion approach. In 3-on-3 situations, masking information "pick up" from areas other than the ball or ball passer had a more detrimental effect on the experienced players' performances, suggesting differences in selective attention. In 1-on-1 situations, occluding an oncoming dribbler's head and shoulders, hips, or lower leg and ball region did not affect the experienced players' performances more than the less experienced group. The disparities in search strategy observed in Experiment 1 did not directly relate to differences in information extraction. Experiment 3 used concurrent verbal reports to indicate where participants extracted information from while viewing 3-on-3 sequences. Experienced players spent less time attending to the ball or ball passer and more time on other areas of the display. Findings highlight the advantages of integrating eye movements with more direct measures of selective attention.

Attention↗
PubMed1997

Structure of human transferrin receptor oligosaccharides: conservation of site-specific processing.

The human transferrin receptor (TfR) has three N-linked oligosaccharides. A combination of site-directed mutagenesis and carbohydrate and protein chemistry was used to characterize the structures of the N-linked oligosaccharides and to map their locations. We find that the type of oligosaccharide at each position was unique for that particular site. Human TfR isolated from placentae was used to characterize the structure of the oligosaccharides found in the native TfR. Following digestion of purified TfR with trypsin, individual peptides were obtained via RP-HPLC and were assayed for monosaccharides by strong acid hydrolysis and HPAE-PAD. Peptides containing carbohydrate were subjected to amino acid sequencing to identify the specific Asn residue. The oligosaccharides at Asn 251 are of the complex type. HPAE-PAD and FACE analysis suggests that they are triantennary and trisialylated with core fucosylation. The glycopeptide containing the site at Asn 317 was obtained after limited tryptic digestion and RP-HPLC. FACE analysis reveals predominantly a family of sialylated hybrid oligosaccharides. The consensus sequences for each N-linked site were mutated in various combinations and the resultant TfRs expressed in mouse 3T3 cells. Endoglycosidase H digestion of the mutated TfRs indicates that the pattern of oligosaccharides is consistent with the type of oligosaccharides found at each position in human tissue and the glycosylation of one site does not directly affect the glycosylation of other sites. Previous studies indicated that the oliosaccharide at Asn 727 was high-mannose type [Hayes, G. R., et al. (1995) Glycobiology 5, 227-232]. These results indicate that the type of oligosaccharide found at each site is most dependent on the environment surrounding it.

3T3 Cells↗
PubMed1997

alpha1B adrenoceptors in rat paraventricular nucleus overlap with, but do not mediate, the induction of c-Fos expression by osmotic or restraint stress.

A role has been suggested for hypothalamic alpha1 adrenoceptors in the acute stress-induced activation of the hypothalamic-pituitary-adrenal axis. Using a polyclonal antiserum against the rat alpha1B adrenergic receptor protein, we have demonstrated alpha1B receptor immunoreactivity in neurons and especially in punctate cell processes in the rat paraventricular nucleus. The distribution of alpha1B receptor immunoreactivity overlapped in part with the distributions of c-Fos immunoreactivity induced in the paraventricular nucleus by either restraint stress or hypertonic saline administration. However, intraperitoneal pretreatment with the alpha1 receptor antagonist prazosin (0.5 or 5.0 mg/kg) failed to attenuate stress-induced c-Fos expression in the paraventricular nucleus. Prazosin also failed to attenuate the secretion of corticosterone following restraint stress. Thus, we conclude that neither acute secretory activity nor activation of gene transcriptional responses mediated by c-Fos in the hypothalamic pituitary adrenal axis following these stressors are dependent upon hypothalamic alpha1 adrenergic receptors.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed1997

Localized pigmented villonodular synovitis: a rare cause of locking of the knee.

A 34-year-old woman presented with a history of recurrent episodes of knee locking and swelling. Arthroscopy revealed characteristic brown colored pedunculated lesions in the intercondylar notch region. These were clearly causing interference to joint motion. The lesions were resected arthroscopically with prompt resolution in symptoms. Histological examination confirmed pigmented villonodular synovitis.

Adult↗
PubMed1997

Co-localization of alpha1D adrenergic receptor mRNA with mineralocorticoid and glucocorticoid receptor mRNA in rat hippocampus.

Many adaptive changes occur in response to chronic or repeated stress, involving complex regulatory interactions between central stress-related afferents and the central components of the hypothalamo-pituitary-adrenal (HPA) axis. One change associated with chronic stress is an attenuation of corticosteroid receptor-mediated feedback inhibition of the HPA axis, a process thought to involve corticosteroid receptors in the hippocampus. A prominent stress-related central afferent that innervates the hippocampus and that may participate in the regulation of the HPA axis is the central noradrenergic system. Previous evidence suggests that alpha1 adrenergic receptors may down-regulate hippocampal corticosteroid receptors, and may thus contribute to stress-induced facilitation of HPA responses. In the present study, we used combined nonisotopic and radioisotopic in situ hybridization to examine the overlapping expression and co-localization of mRNA encoding the post-synaptic alpha1D adrenergic receptor subtype, the major alpha1 subtype expressed in hippocampus, with mRNA for the two corticosteroid receptor subtypes, type I (mineralocorticoid receptor, MR) and type II (glucocorticoid receptor, GR) in rat hippocampal neurons. We observed overlapping distributions and an extensive degree of co-localization of alpha1D receptor mRNA with both corticosteroid receptor subtype messages, establishing an anatomical substrate by which these two receptor systems may directly regulate each other. The potential interaction between co-localized adrenergic and corticosteroid receptors in hippocampus may contribute to stress-induced alterations in the HPA response to subsequent stress.

Animals↗
PubMed1997

A place in the sun: international retirement migration from northern to southern Europe.

"This article considers four aspects of IRM [international retirement migration]. The first considers the limited literature on this... topic and identifies the distinctiveness of both its international and European features. The second reviews the existing statistical data for north-south IRM in Europe, particularly from the UK to Italy, Malta, Portugal and Spain; it establishes both the scale and the geography of these migrations. In the third section we investigate some of the major influences on both the volume and the spatial pattern of IRM. Finally, in the fourth section, a brief review is presented of the economic, social and cultural implications of IRM for both the emigrants and their host communities."

Data Collection↗