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Biomedical subjects

J Stapleton

Publications and source records attributed to J Stapleton.

At least 19 recordsLinked to original sources
PubMed1998

Cigarette smoking prevalence, cessation and relapse.

This paper briefly reviews three aspects of cigarette smoking behaviour: recent British trends in prevalence and cessation, tobacco dependence and the nicotine withdrawal syndrome, and treatment for smokers using nicotine replacement therapy. It concludes with a meta-analysis of the effect of relapse in nicotine replacement trials. For many years, until 1994, smoking prevalence in the UK declined at a steady rate but since the early 1980s uptake in the young has remained high. This failure to curb recruitment in the young may be in part responsible for the recent rise in all-age smoking prevalence. Cessation rates are very low when compared with the proportion of smokers who wish to stop and repeatedly try to do so. This disparity can be attributed to the addictiveness of nicotine and the withdrawal symptoms which confront the would-be quitter. To date, the most effective adjunctive aid for smokers trying to quit is nicotine replacement therapy but even when abstinence for several months has been achieved the risk of relapse remains high.

Adolescent↗
PubMed1998

T cell syncytia induced by HIV release. T cell chemoattractants: demonstration with a newly developed single cell chemotaxis chamber.

A chemotaxis chamber has been developed to analyze both the velocity and the directionality of individual T cells in gradients of high molecular mass molecules over long periods of time. Employing this chamber, it is demonstrated that syncytia induced by HIV in SUP-T1 cell cultures release two T cell chemoattractants with approximate molecular masses of 30 and 120 kDa. Neither uninfected single cells nor polyethylene glycol-induced syncytia release detectable chemoattractant, suggesting that these chemoattractants are linked to HIV infection. Soluble gp120 functions as a T cell chemoattractant and the addition of anti-gp120 antibody to syncytium-conditioned medium blocks the high molecular mass chemoattractant activity but not the low molecular mass activity. The addition of anti-CD4 antibody to syncytium-conditioned medium also blocks the high molecular mass chemoattractant activity but not the low molecular mass activity. These results demonstrate that HIV-induced T cell syncytia release a low and a high molecular mass T cell chemoattractant, and suggest that the high molecular mass factor is gp120 and that it functions through the CD4 receptor.

CD4 Antigens↗
PubMed1998

Characterization of the folding pathway of recombinant human macrophage-colony stimulating-factor beta (rhM-CSF beta) by bis-cysteinyl modification and mass spectrometry.

Melarsen oxide [p-(4,6-diamino-1,3,5-triazin-2-yl)aminophenylarsonous acid (MEL)], which selectively bridges spatially neighboring bis-cysteinyl residues in (reduced) proteins, was used to trap folding intermediates chemically during 1) time-dependent renaturation of recombinant human macrophage colony-stimulating factor (rhM-CSF); by redox refolding in vitro; 2) reductive unfolding in the presence of the trapping reagent; and 3) denaturing unfolding reactions in urea and guanidinium hydrochloride. Characterization of intermediates from folding and unfolding reactions was performed by electrospray ionization mass spectometry (ESI-MS). In all folding and unfolding reactions a characteristic dimeric intermediate with two attached melarsen oxide (MEL) groups was observed, suggesting that these rhM-CSF beta species were important refolding intermediates. These intermediates presented a characteristic "charge structure" in ESI spectra with a most abundant 26+ charged molecular ion whereas the mature homodimeric rhM-CSF beta showed a most abundant 23+ molecular ion, indicating that the final product was more compact. The major locations of the two MEL groups were identified by mass spectrometric peptide mapping at cysteine residues C157 and C159 from each monomer. Cysteine residues C7 and C90 were minor modification sites. The mass spectrometric results from the in vitro folding reactions of rhM-CSF beta are in agreement with intrinsic tryptophan fluorescence measurements and are consistent with the folding pathway that starts with a fully reduced monomer (R), includes partially folded monomeric intermediates (M) and dimeric intermediates (D), and yields a final product with the native tertiary structure (N): 2R ==> 2M ==> D ==> N. Our results show that selective chemical trapping of bis-thiol groups of proteins with MEL permits study of folding pathways by mass spectrometric structure characterization of intermediates with otherwise transient conformations.

Arsenicals↗
PubMed1996

Cognitive performance effects of subcutaneous nicotine in smokers and never-smokers.

In a double-blind placebo-controlled crossover study the effects of two doses of subcutaneous nicotine and saline were compared on a range of performance measures in 18 abstaining smokers and 18 never-smokers. Each subject received two injections (40 min apart) of saline, 0.3 mg nicotine, or 0.6 mg nicotine in a balanced order over three sessions. Performance was assessed before and after the injections on nine tests [news recall, Sternberg memory task, finger tapping, logical reasoning, rapid visual information processing (RVIP), long-term word recognition, digit recall, Stroop test, and critical flicker fusion threshold]. In the abstinent smokers, nicotine produced significantly faster correct responses on the logical reasoning test, more target hits, faster reaction times and improved sensitivity on the RVIP task, and more correct responses on word recognition. In never-smokers, nicotine produced faster reaction times on the RVIP and digit-recall tasks, although in the latter case this was at the expense of fewer correct responses. There were no significant differences between the two groups' responses to nicotine but smokers performed worse than never-smokers prior to injections, even controlling for background characteristics. These results are consistent with other recent research suggesting a primary effect of nicotine in enhancing cognitive performance.

Adult↗
PubMed1995

Sources of interracial variation in bone mineral density.

Many studies have demonstrated significant differences in bone mineral density between various racial groups. Although it has been suggested that differences in body weight contribute to such interracial variation, the artifactual effect of the skeletal size inherent in projectional absorptiometry methods has been largely ignored. We have measured bone mineral density by dual-energy X-ray absorptiometry in the lumbar spine and at three femoral sites in 200 premenopausal women of Chinese, Indian, European, or Polynesian origin (50 of similar mean age in each group). In the Chinese and Indian women the measured bone mineral density measurements (g/cm2) were similar, but significantly less, at all sites, than those of European women (p < or = 0.005). The European women were, however, significantly taller than both the Chinese and Indian women (p < 0.0001), and when the scale artifact of absorptiometry was removed by dividing the measured bone mineral density either by the height of the subject, or by the square root of the area over which the X-ray beam was projected, then the differences in mean bone mineral density between the Chinese, Indian, and European women were almost completely eliminated. The Polynesian women were significantly more obese (as judged from mean body mass index) than all the other groups (p < 0.0001) and had significantly greater bone mineral density at all sites than all the other groups both before (p < 0.0001) and after (p < 0.0001) correcting for the scale artifact.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1993

Comparison of pentobarbital alone and pentobarbital in combination with lidocaine for euthanasia of dogs.

Pentobarbital alone, pentobarbital plus 1% lidocaine solution, pentobarbital plus 2% lidocaine solution, and pentobarbital plus 3% lidocaine solution were each used to euthanatize 6 dogs. For each dog, time between the beginning of injection of the euthanasia solution and each of the following events was recorded: collapse, onset of apnea, flat-line electrocardiogram, flat-line electroencephalogram, loss of palpable heartbeat, and loss of palpable pulse. Any signs of pain or discomfort were also recorded. There were no significant differences among groups except for time to flat-line electrocardiogram. Dogs euthanatized with pentobarbital alone had significantly longer times than did dogs euthanatized with pentobarbital in combination with any of the lidocaine concentrations. We concluded that pentobarbital in combination with lidocaine was a reasonable alternative to pentobarbital alone when euthanatizing dogs.

Animals↗
PubMed1993

Transdermal nicotine patches with low-intensity support to aid smoking cessation in outpatients in a general hospital. A placebo-controlled trial.

OBJECTIVE: To assess whether transdermal nicotine patches combined with low-intensity support can help outpatients in a general hospital stop smoking. DESIGN: Randomized, double-blind, placebo-controlled trial with 12 weeks of follow-up. SETTING: Department of Thoracic Medicine in an inner-city public general hospital, London, England. SUBJECTS: Two hundred forty-eight outpatients in a general hospital, who smoked at least 10 cigarettes per day (the majority were being treated for smoking-related diseases), referred by clinicians at the hospital. INTERVENTION: Brief advice to stop smoking and daily application of transdermal nicotine patches (delivering 15 mg over 16 hours) or placebo, with follow-up appointments at 1, 3, 6, and 12 weeks, with a doubling of the dosage for continuing smokers at week 1. MAIN OUTCOME MEASURE: Sustained abstinence from tobacco from week 3 to week 12 validated with measurement of expired-air carbon monoxide concentration at weeks 3, 6, and 12. RESULTS: Twenty-nine (23.4%) of 124 subjects assigned to the nicotine group were validated as having abstained from smoking at both weeks 3 and 6, compared with 16 (12.9%) of 124 subjects receiving placebo (P = .008). At week 12, 22 (17.7%) of the subjects in the nicotine group were validated as having abstained at all three points as were 15 (12.1%) of the subjects in the placebo group (P = .058). CONCLUSION: Transdermal nicotine patches combined with low-intensity support are effective in helping outpatients in a general hospital stop smoking but do not prevent relapse after 6 weeks.

Administration, Cutaneous↗
PubMed1993

Circulating insulin levels are related to bone density in normal postmenopausal women.

We recently established that the dependence of bone mineral density (BMD) on body weight in women is mainly attributable to a close relationship between total body fat mass and BMD. The present study assesses whether this latter relationship might be contributed to by the hormones insulin or amylin, both of which may influence fat mass and calcium metabolism. Fifty-three normal postmenopausal women underwent a 75-g glucose tolerance test with measurement of plasma insulin and amylin concentrations every 30 min for 2 h. Body composition and BMD/height (to provide a quantity with the dimensions of volumetric density that is independent of body size) were measured by dual-energy X-ray absorptiometry, and volumetric density of the third lumbar vertebral body was calculated. Circulating insulin concentrations correlated with BMD/height and volumetric density of the third lumbar vertebral body (r = 0.28-0.52). They also were related to body weight (r = 0.34-0.56) and fat mass (r = 0.38-0.56) but were not independently related to lean mass on multiple regression. There were no consistent relationships between amylin levels and these variables. Multiple-regression analyses with fat mass and insulin levels as independent variables indicated that BMD/height of total body and femoral trochanter were primarily related to fat mass, whereas, in femoral neck, the significant relationship was with insulin. Volumetric density of the third lumbar vertebral body was related to insulin levels alone on this analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Fine-needle aspiration findings of the liver in a case of Q fever.

This report describes the cytologic findings in Q fever involving the liver in a 59-yr-old man. The fine-needle aspiration findings are correlated with a surgical needle biopsy performed concurrently. Cytopathologists should include Q fever in their differential diagnosis of granulomatous inflammation. Ring granulomas, which can be seen in an aspiration biopsy, should suggest the diagnosis of Q fever.

Biopsy, Needle↗
PubMed1992

Lateral spine densitometry is a more sensitive indicator of glucocorticoid-induced bone loss.

Osteoporosis is a common complication of glucocorticoid therapy. Bone density measurement is now commonly used in assessing which steroid-treated patients require specific interventions to reduce fracture risk. The recently developed techniques for the measurement of bone mineral density (BMD) of the vertebral body alone, by dual-energy x-ray absorptiometry (DXA) in the lateral projection, may be particularly useful in this context since steroid-induced bone loss is most marked in trabecular-rich regions like the vertebral body. This possibility has been assessed in the present study by the measurement of BMD in the lateral and anterioposterior (AP) projections in 28 women receiving chronic glucocorticoid treatment. The two BMD measurements were significantly related (r = 0.62, p < 0.001). When expressed in relation to age-appropriate normal values, lateral BMDs were lower than AP BMDs both in percentage terms (70.8 +/- 4.4 versus 90.3 +/- 2.6%, p < 0.001) and in terms of Z scores (-1.42 +/- 0.22 versus -0.91 +/- 0.24, p = 0.027). AP BMD Z scores classified 12 patients as osteopenic, whereas a further 7 were so categorized by lateral BMD Z score. It is concluded that lateral DXA scanning is a more sensitive indicator of glucocorticoid-induced osteopenia than conventional BMD measurement in the AP projection.

Absorptiometry, Photon↗
PubMed1992

Effect of transdermal nicotine patches on cigarette smoking: a double blind crossover study.

The effect of transdermal nicotine patches on ad libitum cigarette smoking was examined in 30 subjects by measuring behavioural, biochemical and subjective aspects of smoking during a week of smoking without patches, and then a week each of nicotine and placebo patches in a randomised double blind crossover design. While wearing nicotine patches the subjects did not reduce the number of cigarettes smoked, but their expired carbon monoxide was reduced by 14%, they obtained less satisfaction from their cigarettes, and reported fewer and weaker urges to smoke. Down-regulation of nicotine intake from cigarettes was imprecise, such that when subjects wore nicotine patches their post-cigarette plasma nicotine concentration increased to an average of 45 ng/ml compared with 37 ng/ml in both no patch and placebo patch conditions. As the nicotine patches produced a plasma nicotine concentration of 15.9 ng/ml in abstinent subjects, this suggests a 22% reduction in nicotine intake from cigarettes while wearing nicotine patches. No serious symptoms of nicotine overdose were reported. It is suggested that the continuous absorption of nicotine from the patch may cause a build-up of acute tolerance to both toxic and pleasant subjective effects from smoking.

Administration, Cutaneous↗
PubMed1992

Nasal nicotine spray: a rapid nicotine delivery system.

Plasma nicotine concentrations following administration by two types of nasal nicotine spray were compared in ten subjects. Absorption was particularly rapid during the first 2.5 min, the average rise in blood nicotine concentrations during this time being 8.6 ng/ml for the two products, followed by a small further rise to an average peak increase of 10.5 ng/ml 5 min after the dose of 2 mg nicotine base (mean 27.8 micrograms/kg). Despite a four-fold Cmax variation between subjects, the levels of individual subjects were fairly consistent across the two products. There were no significant differences between the two products in blood nicotine concentrations or cardiovascular responses, and the correlation between the AUCs from the two products was 0.68 (P = 0.01). Eight subjects reported subjective feelings of light-headedness or slight dizziness, which are not typical after slower absorption from nicotine gum or skin patches. Blood nicotine levels within the smoking range were soon built up with repeated doses, even in the subject with the least efficient nasal absorption. In a second study of ad libitum use under clinical conditions both products appeared sufficiently acceptable for therapeutic use as an aid to smoking cessation. There was no tendency to escalate to excessive use over 4 weeks, and blood nicotine concentrations in nine subjects averaged only 44% of their prior smoking levels. Only one subject had levels equivalent to prior smoking and possible reasons why this was not more common are discussed.

Administration, Intranasal↗
PubMed1991

Migration to rural areas by HIV patients: impact on HIV-related healthcare use.

OBJECTIVE: To evaluate the impact of patient migration on human immunodeficiency virus (HIV)-related healthcare use in a rural setting. DESIGN: Data were collected on all patients seeking medical care related to HIV infection at The University of Iowa HIV/acquired immunodeficiency syndrome (AIDS) clinic. Information was collected related to patient care, stage of illness, prior and current residence, and clinic and hospital use. SETTING: An outpatient clinic in a university hospital offering primary and consultative medical care for persons with HIV infection. PATIENTS: All patients scheduled into clinic reported a previous positive HIV serologic test. RESULTS: Forty-five percent (81 of 181) of patients reported moving to Iowa, yet no more than 11% (n = 20) moved out of the state during the same period of observation. Of patients meeting the Centers for Disease Control criteria for AIDS, 24% were diagnosed prior to moving to Iowa (18 of 74). Twenty-seven percent of AIDS-related inpatient days of hospitalization and 19% of AIDS-related outpatient clinic visits were used by persons diagnosed in another state. Lifetime charges totalled for eight patients ranged from $24,873 to $232,556, with a mean of $109,934. CONCLUSIONS: A substantial portion of HIV-related healthcare in our rural area was used by individuals who had migrated to or back to Iowa. Further understanding of the reasons for and the extent of HIV patient migration to rural areas is needed.

Adult↗