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Biomedical subjects

M Anderson

Publications and source records attributed to M Anderson.

At least 145 records · Page 8Linked to original sources
PubMed1999

Expression of transforming growth factor beta type II receptors in head and neck squamous cell carcinoma.

Transforming growth factor (TGF)-beta is a potent regulator of growth and differentiation in normal squamous epithelium. TGF-beta exerts its antiproliferative effect via the TGF-beta type II receptor (TbetaR-II). A decrease in TbetaR-II expression is believed to be responsible, in part, for the resistance of squamous cell carcinoma (SqCC) to the anti-proliferative effects of TGF-beta. In the present study, we used immunohistochemistry and in situ hybridization to analyze the expression of TbetaR-II along the successive oncogenic stages of head and neck squamous neoplasia, from normal epithelium to dysplasia to carcinoma. Quantitation of TbetaR-II expression in 38 SqCCs was assessed on a visual scale ranging from negative (absence of staining) to 3+ (strong staining). Normal squamous epithelium and squamous epithelium in the vicinity of the tumors showed homogenous receptor expression with moderate intensity. Dysplastic epithelium and carcinoma in situ showed a mild decrease in receptor expression intensity. Well-differentiated to moderately differentiated carcinomas showed heterogeneous expression of variable intensity, and poorly differentiated carcinomas were completely devoid of TbetaR-II. In every tumor, the superficial component showed more intense receptor expression than the invasive component. These results indicate that TbetaR-II expression inversely correlates with disease aggressiveness and suggest that aberrant TbetaR-II expression is a contributing factor to the pathogenesis of SqCC.

Activin Receptors, Type I↗
PubMed1999

Behavior based safety. A different way of looking at an old problem.

1. The occupational and environmental health nurse role in behavioral safety initiatives can very to include: serving as a leader, change agent, collaborator with safety professionals, consultant, team participant, educator, coach, and supporter to employees and management. 2. Behavior based safety and health initiatives add to existing knowledge and techniques for improving the health and safety of workers. 3. Behavior based safety relies on employee involvement and places a strong emphasis on observation, measurement, feedback, positive reinforcement, and evaluation. It focuses on identification of system improvements and prevention.

Accidents, Occupational↗
PubMed1999

The use of self organizing maps to evaluate myoelectric signals.

This paper presents a study of the use and accuracy of self-organizing maps (SOM) in classifying myoelectric signal properties. Myoelectric signals were obtained and classified for four upper-limb movements (elbow flexion, elbow extension, wrist pronation and wrist supination) and their force category. This was done for isolated actions as well as for multiple action sequences. The success of the developed SOM ranged from 92%-97% when determining the motion, from 81%-87% in determining the force category, and from 59%-96% in determining sequences of motions. These successes are encouraging for the continued development of this technique for use in controlling real-time complex motions in prosthetic devices.

Action Potentials↗
PubMed1998

Interaction between paired-pulse facilitation and long-term potentiation in the projection from hippocampal area CA1 to the subiculum.

Studies of the interaction between long-term potentiation (LTP) and paired-pulse facilitation (PPF) may throw light on the role of presynaptic factors in LTP. We examine here, for the first time, the nature of PPF in the CA1-subiculum projection. PPF peaks at a 50 ms interstimulus interval (ISI) and is evident at ISIs from 10 to 500 ms. There is no PPF effect at a 1000 ms ISI. PPF decreases in magnitude post-LTP induction across the middle range of ISI values tested (30, 50 and 100 ms). There is a positive correlation between initial PPF values and LTP; this correlation increases as the ISI increases. Initial values and the change in PPF post-LTP are also negatively correlated.

Animals↗
PubMed1998

The CHO XRCC1 mutant, EM9, deficient in DNA ligase III activity, exhibits hypersensitivity to camptothecin independent of DNA replication.

We have analyzed the X-ray-sensitive CHO mutant cell line EM9 for sensitivity to the topoisomerase I inhibitor comptothecin. These cells exhibit defective repair of single strand DNA breaks. Recently, EM9 were complemented the DNA ligase III interactive protein, XRCC1. Defective XRCC1 apparently accounts for the low DNA ligase III activity that may explain the single-strand break repair deficiency of EM9 cells. Here, we demonstrate cytotoxic hypersensitivity of EM9 cells following a brief camptothecin treatment. Both the S-phase and non-S-phase populations of EM9 exhibited camptothecin sensitivity relative to the parent cell line AA8. In AA8 cells, only the 55% of the population corresponding to the S-phase subpopulation were sensitive to camptothecin, while the remainder of the population were totally resistant to doses as high as 10 microM. The role of DNA replication in the camptothecin sensitivity was studied using the DNA polymerase inhibitor aphidicolin in co-treatment with camptothecin. Aphidicolin treatment fully protected AA8 cells from camptothecin cytotoxicity. In EM9 cells, aphidicolin protected the S-phase fraction to some degree but all the cells remained sensitive to camptothecin cytotoxicity. These results suggest that EM9 cells are sensitized to camptothecin by a mechanism that is independent of DNA replication and may be a consequence of the XRCC1 mutation or the associated deficiency in DNA ligase III activity. Mechanistic models for the replication-independent cytotoxicity of camptothecin in EM9 cells are discussed.

Animals↗
PubMed1998

The projection from hippocampal area CA1 to the subiculum sustains long-term potentiation.

Long-term potentiation (LTP) is a popular model of the synaptic plasticity which may be engaged by the biological processes underlying learning and memory. Most available studies of LTP have concentrated on the analysis of LTP occurring in 'early' components of the hippocampal circuit (for example, dentate gyrus and area CA1). We examine here, for the first time, LTP as it occurs in the massive, unidirectional projection from CA1 to the subiculum in vivo. We show that this projection sustains high-frequency stimulus-induced LTP (10 trains of 20 stimuli at 200 Hz; intertrain interval 2 s; LTP 181 +/- 9% at 30 min post-LTP induction). In addition, input-output (I/O) curves show a leftward shift for all stimulation values.

Animals↗
PubMed1998

Lipid-lowering effects of WAY-121,898, an inhibitor of pancreatic cholesteryl ester hydrolase.

WAY-121,898 is an inhibitor of pancreatic cholesteryl ester hydrolase (pCEH). After confirming its in vitro potency and relative lack of a major effect on acyl-CoA:cholesterol acyltransferase (ACAT), it was found that this compound lowers plasma cholesterol in cholesterol-fed, but not chow-fed, rats. Measures of liver cholesteryl ester content and the direct determination of cholesterol absorption (lymph-fistula model) show that inhibition of cholesterol absorption is at least one mechanism for the observed cholesterol lowering. However, WAY-121,898 was also active when administered parenterally to cholesterol-fed rats, and in cholesterol-fed hamsters cholesterol-lowering occurred with oral dosing despite no change in cholesterol absorption, suggesting other modes of action possibly relating to inhibition of liver CEH. Combination treatment in cholesterol-fed rats with the ACAT inhibitor CI-976 resulted in a greater-than-additive reduction in plasma cholesterol, implying that both pCEH and ACAT may play a role in cholesterol absorption in this species. In rabbits, WAY-121,898 prevented the rise in plasma cholesterol due to the feeding of cholesteryl ester but not in rabbits fed (free) cholesterol. In guinea pigs, the compound induced an increase in adrenal cholesteryl ester mass. Taken together, the overall profile in these animal models suggests that WAY-121,898 inhibits more than just the intestinal (lumenal) pCEH, and that the role of this enzyme in cholesterol metabolism may be different within and across species, the former depending upon the dietary cholesterol load.

Administration, Oral↗
PubMed1998

Morphology and ultrastructure of sense organs on the ovipositor of Trybliographa rapae, a parasitoid of the cabbage root fly.

The ovipositor of the parasitoid wasp Trybliographa rapae was examined by scanning and transmission electron microscopy. Characteristic peg-like sensilla with a cuticular ring at the base are found at the tip of the ventral valves, where they occur in a characteristic arrangement of triplets. The unusual basal structure probably protects the sensilla against damage during movement through the substrate and piercing of the host cuticle. These sensilla are each innervated by six dendrites, some of which have lamellated tips, generally considered to be characteristic of thermosensitivity. It is suggested that the remaining dendrites are gustatory, and as such probably respond to factors present in host haemolymph. A second type of peg-like sensillum is found on both the dorsal and the ventral valves. These are set in deep pits so that only the tip of the peg protrudes above the surface of the cuticle. These occur along the length of the ovipositor shaft and ultrastructural studies reveal the pegs to be innervated by a single mechanosensitive dendrite, probably monitoring the movement of the ovipositor through the substrate.

Journal Article↗
PubMed1998

Primary pneumococcal peritonitis complicated by exudative pleural effusion in an adolescent girl.

A healthy, young adolescent girl developed primary pneumococcal peritonitis, an infection rarely reported in this age group in North America. Her course was further complicated by exudative pleural effusion and pneumonia despite receiving 10 days of clindamycin therapy. Laparascopy proved useful in making the initial diagnosis, but may have contributed to the pathogenesis of the pulmonary process. Case presentation, management, and etiology are discussed.

Adolescent↗
PubMed1998

Evaluating an alternative funding plan.

There have been increasing levels of interest shown across Canada in the potential application of alternative funding arrangements for academic health science centres. This article outlines the approach, and some preliminary results, of the alternative funding plan evaluation at Queen's University. Following a discussion of the AFP itself, the article describes the first phase of the evaluation process. Several studies nearing completion are outlined, as are other pieces of research that will be conducted before the AFP is renegotiated in 1999. Finally, the authors provide a brief discussion of the organizational and methodological issues that emerge when evaluating an AFP.

Academic Medical Centers↗
PubMed1998

A relic S-RNase is expressed in the styles of self-compatible Nicotiana sylvestris.

We surveyed ribonuclease activity in the styles of Nicotiana spp. and found little or no activity in self-compatible species and in a self-compatible accession of a self-incompatible species. All self-incompatible species had high levels of ribonuclease activity in their style. Interestingly, one self-compatible species, N. sylvestris, had a level of stylar ribonuclease activity comparable to that of some self-incompatible Nicotiana species. A ribonuclease with biochemical properties similar to those of the self-incompatibility (S-)RNases of N. alata was purified from N. sylvestris styles. The N-terminal sequence of this protein was used to confirm the identity of a cDNA corresponding to the stylar RNase. The amino acid sequence deduced from the cDNA was related to those of the S-RNases and included the five conserved regions characteristic of these proteins. It appears that the N. sylvestris RNase may have evolved from the S-RNases and is an example of a 'relic S-RNase'. A number of features distinguish the N. sylvestris RNase from the S-RNases, and the role these may have played in the presumed loss of the self-incompatibility response during the evolution of this species are discussed.

Amidohydrolases↗
PubMed1998

Fertility decline in Scotland, England and Wales, and Ireland: comparisons from the 1911 census of fertility.

Data on family size by year of marriage, age at marriage, and duration of marriage, from the 1911 Fertility Census, are compared between Scotland, England and Wales, Irish county boroughs, and the rest of Ireland. While means show significant inter-country differences, from the 1880s marked similarities are found across all the countries in the pattern of fertility decline, strongly suggesting significant fertility limitation in rural Ireland well before 1911. Noting the implications for the use of rural Ireland as a natural fertility population, the data are instead compared with the Coale-Trussell and Hinde-Woods schedules. The former provides more plausible results, which imply strong period rather than cohort effects in the fertility decline. Except in rural Ireland, little evidence is found for significant fertility limitation early in marriage among younger marrying couples, but many older marrying couples appear to have stopped childbearing at very low parities from an early date.

Censuses↗
PubMed1998

Highly restricted fertility: very small families in the British fertility decline.

From the earliest stages of the British fertility decline, falling mean family size was accompanied by marked rises in the proportion of married women who remained childless or who bore only a single child. This paper summarises those changes, their impact on average family size, and the implications for estimates of the proportions of couples who attempted to space their children in the early years of marriage. The explanatory power of some commonly cited interpretations of the general decline in marital fertility is then considered in the context of this growth in number of families of highly restricted fertility. The paper highlights a need for more emphasis on descriptive and analytical approaches that are sensitive to distributions within populations. Also emphasized is the importance of developing interpretations that allow for the possibility that different factors may operate on different sub-sets of families at different points in time.

Birth Rate↗
PubMed1998

Hepatitis B immunization in a university student population.

In the United States, hepatitis B virus infection occurs predominantly among adolescents and young adults, despite the availability of an effective vaccine. Immunization status and hepatitis B virus (HBV) vaccine acceptance among 505 students visiting the student health services of a large southern university were investigated. Only 58 students had received HBV vaccine. The cost of the vaccine was paid by the students personally (35.5%) or by their parents (34.5%) or employers (31.0%). Nearly half of the students (45.7%) did not know their vaccination status. Lower immunization percentages were found among Hispanics, men, persons of lower education levels, and students aged 25 years and under. Being immunized was related to the perception that the vaccine was affordable, although most students (95.7%) said that the cost of HBV vaccine was excessive. Health professionals' emphasis on the need for HBV vaccination and a reduction in the price of the vaccine could improve HBV immunization rates among university students.

Adult↗
PubMed1998

Memory span, naming speed, and memory strategies in poor and normal readers.

Eleven-year-old severely impaired poor readers failed to show a word length effect with pictorial presentation, but showed an effect of equal magnitude to that of reading age and chronological age controls with auditory presentation. The lack of a pictorial word length effect was unlikely to be due to slow speed of naming skills, as in one study these were at least as fast as those of the reading age controls. It is possible that the poor readers failed to verbally encode the pictures. However, they reported using verbal rehearsal, and lip movements were often observed during presentation, suggesting that they did verbally encode the items. Therefore they may have failed to show a word length effect because they did not retrieve information from the phonological store at recall. Although the poor readers had impaired naming speed skills for their age on both discrete item identification and articulation rate tasks, they could not be equated with their chronological age controls on memory span or reading when these naming speed differences were controlled. However, the groups were matched on the naming speed measures when differences in reading ability were controlled.

Child↗