Search PubMed⌕ Search

Biomedical subjects

R West

Publications and source records attributed to R West.

At least 109 records · Page 6Linked to original sources
PubMed1999

A cephalometric study of class II Division 1 malocclusions treated with the Jasper Jumper appliance.

This lateral cephalometric study investigated the dental and skeletal effects of the Jasper Jumper appliance used in the correction of Class II Division 1 malocclusions. A sample of 36 growing patients treated with the Jasper Jumper appliance was divided into two groups: (1) 24 patients with records obtained at the start and completion of orthodontic treatment, and (2) 12 patients with records available at the beginning and end of the Jumper phase of treatment. Treatment effects were determined by statistical comparisons of cephalometric changes in the patients relative to age-adjusted cephalometric standards, and from structural superimpositions. While the Jumpers were in place, maxillary incisors were retroclined and the molars were moved distally, tipped back, and intruded. The mandibular incisors were proclined and intruded, while the molars were translated mesially, tipped forward, and extruded. Skeletal measures showed reduced forward maxillary displacement and no significant alteration of horizontal mandibular growth. During orthodontic finishing, molar tipping and maxillary incisor retroclination were corrected, although the mandibular incisors remained proclined. In summary, this study found that the Jasper Jumper appliance corrected Class II discrepancies largely through maxillary and mandibular dentoalveolar effects and, to a limited extent, by restraint of forward maxillary growth.

Activator Appliances↗
PubMed1999

Haemostatic and fibrinolytic responses to bone marrow transplantation.

Thrombin and plasmin activation markers were serially measured in 80 patients undergoing bone marrow transplantation (BMT). There were prothrombotic and fibrinolytic responses observed during autograft and allograft BMTs. Thrombin-antithrombin and prothrombin fragment F1+2 levels increased from day -7 to -3 (P<0.0001) from 3.7 to 7 ng/ml and 1.2 to 1.63 nmol/l, respectively. A rise in plasmin-antiplasmin levels occurred between days 4 and 14 (P< 0.0004), from 393 ng/ml on day -7 to a peak of 795 ng/ml on day 11. No correlation between reduced protein C levels post-BMT and a prothrombotic state was observed.

Adolescent↗
PubMed1999

Alterations of the retinoic acid receptor alpha (RAR alpha) gene in myeloid and lymphoid malignancies.

The retinoic acid receptor alpha (RAR alpha) protein plays a central role in myeloid differentiation, and chromosomal translocations disrupting the RAR alpha gene are implicated in the development of acute myeloid leukaemia (AML). To identify haemopoietic malignant disorders which may also be linked to RAR alpha abnormalities, Southern blot analysis was performed in DNA from 153 patients with haematological malignancies other than AML FAB type M3 using RAR alpha cDNA probes. Alterations of RAR alpha were detected in 1/42 myelodysplastic syndromes (MDS), 2/24 AML, 3/47 B-chronic lymphocytic leukaemias (B-CLL), 0/40 lymphomas and 0/60 normal individuals. These data strongly suggest that alterations of RAR alpha might predispose for myeloid and lymphoid disorders.

Blotting, Northern↗
PubMed1999

Age differences in lapses of intention in the Stroop task.

The study evaluated the hypothesis that older adults are more susceptible to lapses of intention (lapses) than are younger adults, and explored the factors contributing to these lapses. The findings of three experiments examining the pattern of intrusion errors in the Stroop task revealed that older adults were more likely to experience lapses than were younger adults, and that lapses tended to be of longer duration in older than younger adults. Lapses were observed under conditions of suboptimal controlled attentional processing, when task conditions required the allocation of this processing in the service of multiple behavioral goals, and during periods of slowed responding. The findings of these experiments are consistent with those from a growing number of studies indicating that older adults are more susceptible to lapses of intention than younger adults.

Aged↗
PubMed1999

Visual distraction, working memory, and aging.

In two experiments, the effects of taxing selective attention processes on the efficiency of working memory processes were considered in relation to normal aging. In both experiments, the presence of task-irrelevant information disrupted the efficiency of working memory processes, and the effect was generally greater for older than for younger adults. The presence of distracting information increased the frequency of intrusion errors in both younger and older adults and of memory-based errors in older adults. These findings suggest that distraction disrupts both the ability to maintain a coherent stream of goal-directed thought and action in younger and older adults and the encoding and retention of relevant information in older adults.

Adult↗
PubMed1999

Childhood blood lead screening in Arkansas: recommendations for health care providers.

Multiple studies documenting regional differences in prevalence of elevated blood lead levels suggest that children are not at equal risk for lead exposure. In late 1997, the Centers for Disease Control and Prevention (CDC) published guidelines to help states and communities make decisions regarding screening practices. To apply these guidelines to Arkansas Department of Health blood lead data for the 8,883 screens completed in state fiscal year 1997, along with 1990 Census Bureau housing and poverty statistics, were compiled and reviewed. Based upon CDC criteria and other available information, conservative recommendations for blood lead screening are presented for each county in the state. Lead toxicity in children remains a significant public health concern in certain regions of the country. Between 1991-1994, it was estimated about 930,000 U.S. children one to five years old had lead levels > or = 10 micrograms/dL. Children most at risk include minorities, those residing in large central cities, and those living in poverty. Blood lead levels (BLL's) as low as 10 micrograms/dL have been linked with possible IQ deficits as well as learning and behavior problems. To date, no study has demonstrated benefit from reduction of blood lead levels in the 10-24 micrograms/dL range. Nonetheless, in 1991 the Centers for Disease Control and Prevention (CDC) published guidelines for screening and followup designed to detect lead levels this low, presumably in order to prevent additional exposure and perhaps shorten the duration of toxicity. These guidelines essentially called for universal screening of one- and two-year old children regardless of socioeconomic status or previous population-based results of lead screening in their locale. [table: see text] Since release of the controversial 1991 guidelines, several reports of lead toxicity prevalence surveys from diverse communities have demonstrated extreme variation in the magnitude of the problem. For example, in 1994 only 0.6% of Alaska Medicaid recipients six years or younger had lead levels > or = 10 micrograms/dL, with the highest being 11 micrograms/dL.

Arkansas↗
PubMed1998

4-[(1H-imidazol-4-yl) methyl] benzamidines and benzylamidines: novel antagonists of the histamine H3 receptor.

A series of amidine substituted phenyl-, benzyl-, and phenethylimidazoles based on the known H3 agonist SK&F 91606 (4) has been synthesized and tested as ligands for the histamine H3 receptor. Insertion of a phenyl ring between the imidazole ring and the amidine moiety produces antagonists. The benzyl series was found to be the most potent and was further investigated. Compounds 9c and 18 (entries 5 and 12, Table 1) are potent ligands for the H3 receptor with K(i) values of 16 nM and 7.2 nM respectively. In vivo, both compounds were shown to be equipotent to thioperamide (2), the standard H3 antagonist.

Animals↗
PubMed1998

Trans-4-methyl-3-imidazoyl pyrrolidine as a potent, highly selective histamine H3 receptor agonist in vivo.

Extensive structural modification of immepyr (+)-2 led to the discovery of trans-4-methyl-3-imidazoyl pyrrolidine (+/-)-3a as a potent and highly selective H3 agonist. The pyrroline (+/-)-3a was resolved, and its (+) enantiomer, Sch 50971 [(+)-3a], showed a greater separation of H3 and H1 activities in vivo (H3/H1 ratio >> 330) than (R)-alpha-methylhistamine (+)-1 (H3/H1 ratio = 17), the standard H3 agonist.

Animals↗
PubMed1998

Double-blind placebo controlled trial of dextrose tablets and nicotine patch in smoking cessation.

In a placebo-controlled double-blind trial 308 smokers were individually randomly allocated to one of four groups: 1) 3 g dextrose tablets and 15 mg nicotine transdermal patch; 2) dextrose and placebo patch; 3) placebo tablets and nicotine patch; 4) placebo tablets and placebo patch. Patients were scheduled to attend weekly smokers clinic sessions starting 1 week before the quit date and continue for 4 weeks after that date. The primary outcome variable was biochemically verified abstinence at the final session, four weeks after the scheduled quit date. The proportion of smokers abstinent in the four groups was as follows: 49% - dextrose plus active patch; 44% - dextrose plus placebo patch; 36% - placebo tablet plus active patch; 30% - placebo tablet plus placebo patch. The difference between the dextrose and placebo tablets (13%) was statistically significant (P < 0.01, one-tailed); the difference between the active and placebo patches (6%) was not. There was no significant difference between the effect of the dextrose when accompanied by active versus placebo patches. There was no significant effect of dextrose on weight. The results suggest that dextrose supplementation to the diet may be a cheap and simple aid to giving up smoking. Further research is now needed to establish its long-term efficacy.

Adolescent↗
PubMed1998

Effects of increased response dominance and contextual disintegration on the Stroop interference effect in older adults.

In the study we considered the ability of the relative speed of processing-automaticity (RSOP-A) and contextual disintegration (CD) models of the Stroop interference effect to account for the age-related increase in Stroop interference typically observed in older adults. Findings from the first experiment were partially consistent with predictions of the RSOP-A model because response dominance was greater for older adults than for younger adults. However, the age-related increase in interference was independent of this increase in response dominance, suggesting that factors other than those postulated in the RSOP-A model contributed to the greater interference observed in older adults. Results of the second experiment were consistent with the CD model, which suggests that older adults had difficulty maintaining a color-naming strategy to guide task performance.

Adult↗
PubMed1998

The contribution of impaired working memory monitoring to performance of the self-ordered pointing task in normal aging and Parkinson's disease.

The factors contributing to the working memory deficit observed in older adults and individuals with Parkinson's disease on the Self-Ordered Pointing Task were examined in 2 experiments. A detailed analysis of the error data revealed that errors tended to be clustered toward the end of a trial and that this effect was somewhat independent of set size. This pattern was proposed to result from a monitoring deficit where individuals failed to maintain an integrated representation of how far they had proceeded in the trial, an interpretation consistent with animal work by M. Petrides (1995).

Adolescent↗