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Biomedical subjects

R J Williams

Publications and source records attributed to R J Williams.

At least 109 records · Page 6Linked to original sources
PubMed1998

Self-efficacy for refusal mediated by outcome expectancies in the prediction of alcohol-dependence amongst young adults.

The present study examined the relative importance of outcome expectancies and self-efficacy [1] in the prediction of alcohol dependence [2] and alcohol consumption in a sample of young adult drinkers drawn from a milieu previously reported as supportive of risky drinking. In predicting alcohol dependence, outcome expectancies were found to mediate self-efficacy and the same pattern was found for both males and females. This suggests that male and female drinkers may become more similar as they progress along the drinking continuum from risky drinking to dependent drinking. However, in women, in comparison to men, a greater array of expectancies and self-efficacy scales were found to predict heavy drinking, as measured by quantity and frequency. These results suggest that heavy drinking women are particularly at risk of developing drinking related complications and that preventative education needs to take into account gender differences.

Adult↗
PubMed1998

Rapid diagnosis of simian varicella using the polymerase chain reaction.

Simian varicella virus (SVV) causes sporadic epizootics of a varicella-like disease in nonhuman primates. Rapid diagnosis of simian varicella is critical in controlling epizootics. A polymerase chain reaction (PCR)-based diagnostic assay for detection of SVV DNA in cell culture and clinical samples from SVV-infected monkeys was developed. The assay is rapid, specific, and highly sensitive. The SVV DNA is readily detected in skin rash specimens and in peripheral blood lymphocytes of infected monkeys during the early stages of clinical varicella. In addition to providing an important diagnostic tool, the SVV PCR assay is also useful for investigating the epidemiology and pathogenesis of simian varicella.

Animals↗
PubMed1998

Hamstring and patellar tendon graft response to cyclical loading.

This study evaluates the effect of submaximal cyclical loads on the tendinous portion of the central 10 mm of the patellar tendon compared with doubled semitendinosus and gracilis tendons. Six fresh-frozen cadaveric knee specimens were used for the study. There was no significant difference between the cross-sectional areas of a 10-mm patellar tendon and four strands of hamstring tendon (looped semitendinosus and gracilis) from the same specimen. The mean cross-sectional area was 44.4 mm2 for the patellar tendon and 47.5 mm2 for the four strands of hamstring. The specimens were cyclically loaded for 1000 cycles from 0 to 300 N at a rate of 1 Hz; the materials testing machine was set on load control. There were no significant differences in the strain, stress, or modulus between the 10-mm patellar tendon and four strands of hamstring tendon after 1000 cycles of loading to 300 N. These data substantiate the excellent clinical results obtained with either graft source and support the use of either graft source for ACL reconstruction.

Aged↗
PubMed1998

Reductionism in physical sciences.

The idea of reductionism in physical sciences is that all physicochemical observables can be described in terms of a limited number of particles and their variable energies. Here we limit ourselves to atomic descriptions showing how very successful reductionism is in treating equilibrium systems. This includes all properties of single molecules, even DNA, and can be extended to dynamic assemblies of molecules through the variables composition, potential energies, kinetic energies (temperature) and volume (pressure). This description includes the capacity of a system to change, to do work. It does not include working or changing systems when we have to consider time-dependent variables such as directed motion, flow. Analysis of such accidentally or purposefully directed activity seems, to the author, to be outside the above reductionist analysis in that its feature is organization around a 'plan' or a 'cycle'. Thus reductionism fails to describe machines, man-made or biological, in that the parts are arranged, even dedicated, to a total function.

Energy Transfer↗
PubMed1997

Ethanol modulates N-methyl-D-aspartate-evoked arachidonic acid release from neurones.

Glutamate-evokes a Ca2+-dependent release of arachidonic acid from cultured neurones via the activation of NMDA and AMPA receptors. In this study we investigated whether exposing cultured striatal neurones either acutely or chronically to ethanol would modify these responses. Acute ethanol (100 mM, 15 min) inhibited the liberation of arachidonic acid evoked by a maximally effective concentration of glutamate, an affect which appeared to be mediated primarily by a reduction in NMDA receptor responsiveness. In contrast, chronic ethanol exposure caused a dose-dependent increase in the glutamate, N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) evoked release of arachidonic acid, although ethanol was less potent at the AMPA response. Basal responses were not altered by acute or chronic ethanol and the concentrations of ethanol employed were not toxic. Chronic ethanol (100 mM, 48 h) increased NMDA-mediated neuronal damage at sub-maximal concentrations of the agonist, suggesting that an enhanced mobilisation of arachidonic acid may underly the potentiated excitotoxic neuronal loss observed following exposure to ethanol.

Animals↗
PubMed1997

Laguna Negra virus associated with HPS in western Paraguay and Bolivia.

A large outbreak of hantavirus pulmonary syndrome (HPS) recently occurred in the Chaco region of Paraguay. Using PCR approaches, partial virus genome sequences were obtained from 5 human sera, and spleens from 5 Calomys laucha rodents from the outbreak area. Genetic analysis revealed a newly discovered hantavirus, Laguna Negra (LN) virus, to be associated with the HPS outbreak and established a direct genetic link between the virus detected in the HPS cases and in the C. laucha rodents, implicating them as the primary rodent reservoir for LN virus in Paraguay. Virus isolates were obtained from two C. laucha, and represent the first successful isolation of a pathogenic South American hantavirus. Analysis of the prototype LN virus entire S and M and partial L segment nucleotide and deduced amino acid sequences showed that this virus is unique among the Sigmodontinae-borne clade of hantaviruses. Analysis of PCR fragments amplified from a serum sample from a Chilean HPS patient, who had recently traveled extensively in Bolivia (where C. laucha are known to occur), revealed an LN virus variant that was approximately 15% different at the nucleotide level and identical at the deduced amino acid level relative to the Paraguayan LN virus. These data suggest that LN virus may cause HPS in several countries in this geographic region.

Animals↗
PubMed1997

A two-factor model of dietary restraint.

The present study was designed to examine the factorial nature of the Three Factor Eating Questionnaire-Restraint Scale (TFEQ-R) and to compare the relationship of both the Restraint Scale (RS) and TFEQ-R to current dieting, history of dieting, disinhibition, self-esteem and restrained drinking in 144 females. A principal component analysis identified three interpretable factors: Emotional/Cognitive Concern for Dieting, Calorie Knowledge, Behavioral Dieting Control. Only Emotional/Cognitive Concern for Dieting equated with RS as both measures correlated with self-esteem and restrained drinking. Results are discussed in light of other proposed models of dietary restraint and in relation to two recent factors which have been identified in the drinking literature, Cognitive Emotional Control and Cognitive Behavioral Control.

Adolescent↗
PubMed1997

Monocyte chemoattractant protein-2 is a potent agonist of CCR2B.

The binding and functional activity of the CC chemokines monocyte chemoattractant protein-1 (MCP-1), MCP-2, and MCP-3 have been characterized using Chinese hamster ovary DXB-11 cells transfected with the chemokine receptor CCR2B. Receptor binding studies demonstrated that 125I-labeled MCP-1 bound to a single class of high-affinity receptors with a Kd of 0.14 (0.07-0.32) nM. In competition studies MCP-1, MCP-2, and MCP-3 completely inhibited 125I-labeled MCP-1 binding with Ki values of 0.3 (0.16-0.46), 8.8 (3.4-26), and 12.2 (0.6-22) nM, respectively. In calcium mobilization studies, MCP-1 and MCP-3 induced robust elevations in intracellular calcium concentrations, whereas MCP-2 was only weakly active. In contrast, using changes in extracellular acidification rate as a functional readout, all three chemokines were identified as potent agonists of CCR2B. These data demonstrate that MCP-2, in addition to MCP-1 and MCP-3, is a potent agonist of CCR2B and furthermore that MCP-2 activates either different or a subset of the signaling pathways activated by MCP-1 and MCP-3.

Animals↗
PubMed1997

Body dissatisfaction as a mediator of the relationship between dietary restraint and bulimic eating patterns.

The present study was designed to test whether dietary restraint mediates the relationship between body dissatisfaction and bulimic eating patterns in a sample of 172 university females. Contrary to what was expected the results showed that body dissatisfaction mediated the relationship between dietary restraint and bulimic patterns of eating. Thus the results highlight the primary importance of body dissatisfaction as a predictor of bulimic behavior. Body dissatisfaction encompasses a broad array of dimensions such as self-perceptions, cognitions, affect and behavior and it carries enormous explanatory power but its different components remain largely unexplored.

Adolescent↗
PubMed1997

The natural selection of the chemical elements.

Evolution is treated here in a novel way. DNA or any other code is considered to be conservative and therefore, once life began, it would prevent change. Change was imposed upon the DNA code as a stress resulting in vulnerability to "advantageous" DNA damage and mutation. In this respect it is the stress, the changing environment, that opened up a possibility of evolution once an early life form had optimised itself in primitive circumstances. Here I examine the initial slow-coming-to-terms with the environment of primitive life, and then its evolution as the environment forced the DNA into novel development by introducing chemical elements in new forms. The situation today is no different. Environmental change is hostile to present day life and will lead to further evolution.

Biological Evolution↗
PubMed1997

An examination of the binding of aluminum to protein and mineral components of bone and teeth.

Aluminum binding by a variety of noncollagenous proteins associated with bone and teeth (osteopontin, osteocalcin and phosphophoryn) and by hydroxyapatite are examined. The proteins bound aluminum with a dissociation constant, KD, of the 10(-7) M or greater at pH = 7. The number of atoms of aluminum bound was found to be related to but not equivalent to the number of phosphorylated serines in osteopontin and phosphophoryn. Osteocalcin bound one aluminum tightly presumably due to its gamma-carboxyl glutamate residues. Hydroxyapatite bound Al3+ tightly releasing 1.5 equivalent Ca2+ per Al3+ bound. Addition of 3 mM Ca2+, close to the total concentration found in animal circulating fluids, did not effect noticeably the amount of Al3+ bound to bone which must have a KD for Al3+ < 10(-6). Silicic acid added after equilibration with all these materials has little effect but neither the proteins nor hydroxyapatite removed much Al3+ from pre-equilibrated Al3+ solution with silicic acid. The results are discussed with regard to Al3+ poisoning.

Aluminum↗
PubMed1997

Chemokine production by human vascular smooth muscle cells: modulation by IL-13.

1. The production of chemokines by vascular smooth muscle cells (SMC) is implicated in the pathogenesis of atherosclerosis, although the factors regulating chemokine production by these cells are incompletely characterized. 2. We describe the differential stimulation of interleukin-(IL)-8, monocyte chemoattractant protein (MCP)-1 and regulated on activation normal T-cell expressed and secreted (RANTES) synthesis following treatment of human vascular SMC with IL-1alpha or tumour necrosis factor alpha (TNFalpha). Under basal conditions, cultured SMC release very low amounts of IL-8, MCP-1 and RANTES as assessed by specific ELISA. Concentration-response studies with IL-1alpha or TNFalpha revealed that each stimulus induced a similar amount of MCP-1. In contrast approximately three fold more IL-8 was induced by IL-1alpha than by TNFalpha whereas significant RANTES production was induced only by TNFalpha. These findings point to a divergence in the regulation of synthesis of the different chemokines in response to IL-1alpha or TNFalpha stimulation. 3. The T-cell derived cytokines IL-10 and IL-13 were also found to have differential effects on chemokine production by SMC. IL-13, but not IL-10, significantly enhanced IL-8 and MCP-1 release in response to IL-1alpha or TNFalpha. This increase in chemokine release appeared to be accounted for by increased mRNA expression. 4. These findings provide support for the concept that smooth muscle cells can have an active role in a local immune response via the production of chemokines which can be selectively modulated by T-cell derived cytokines.

Cells, Cultured↗
PubMed1997

Immunocytochemical analysis of tissue kallikrein and the kinin moiety in rheumatoid synovial fluid neutrophils.

Polymorphonuclear leucocytes (PMNs) from the synovial fluid of patients with rheumatoid arthritis (RA) showed reduced tissue kallikrein and kinin immunoreactivity in comparison with blood PMNs from healthy individuals as judged visually using confocal microscopy. Similarly, synovial fluid PMNs exhibited reduced tissue kallikrein immunoreactivity as compared with blood PMNs from the same RA patients. Blood PMNs stimulated to degranulate in vitro also displayed less immunostaining for tissue kallikrein and kinin than non-stimulated PMNs. By contrast, no difference in kininogen immunostaining was detected between RA synovial fluid PMNs and blood PMNs from healthy people. It is considered that the results support the hypothesis that tissue kallikrein, released from the granules of RA synovial fluid PMNs, cleaves the kinin moiety from multifunctional kininogen protein on the surface of the PMNs.

Adult↗
PubMed1997

An outbreak of hantavirus pulmonary syndrome in western Paraguay.

During an investigation of hantavirus pulmonary syndrome (HPS) in Paraguay in 1995, sera from persons with HPS-like illness, houshold contacts of confirmed HPS case-patients, and a sample of the area residents were analyzed by ELISA for antibodies to Sin Nombre virus (SNV). Rodent serosurveys and analysis of precipitation records were also conducted. Twenty-three of 24 available probable cases were SNV antibody-positive, 17 of whom were ill between July 1995 and January 1996. Four (14.8%) of 27 case-contacts and 44 (12.8%) of 345 community residents were also seropositive. Calomys laucha (vesper mouse) was the most common rodent species captured and the most frequently SNV-seropositive. Rainfall in May 1995 was 10-fold greater than that seen in May over the preceding 11 years. This 17 case-cluster represents the largest documented outbreak since HPS was first recognized in 1993. Calomys laucha is the likely primary rodent reservoir for a SNV-like hantavirus in western Paraguay. Fluctuations in monthly precipitation rates may have contributed to increased risk for HPS in this region.

Adult↗
PubMed1997

Meeting the challenge of emerging pathogens: the role of the United States Air Force in global influenza surveillance.

Influenza virus is one of the most ubiquitous organisms on the planet, causing illness in much of the population each year. The dynamic nature of the influenza virus requires similarly dynamic surveillance and prevention initiatives. The efforts of national surveillance programs, overseen by the World Health Organization and administered by institutions such as the U.S. Centers for Disease Control and Prevention, the U.S. armed forces, and 60 to 70 collaborating laboratories, annually culminate in the development of effective influenza vaccines. The U.S. Air Force's contribution is via Project Gargle, through which bases in various locations worldwide conduct active surveillance and submit throat swab specimens for virus isolation and characterization; the results of these laboratory analyses help determine the composition of the following year's influenza vaccine. These collaborative efforts have resulted in an identical or close antigenic match between vaccine and epidemic strains in 8 of the last 9 influenza seasons.

Centers for Disease Control and Prevention, U.S.↗