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Biomedical subjects

D Burton

Publications and source records attributed to D Burton.

At least 37 records · Page 2Linked to original sources
PubMed2001

Gender-related differences in slowing colonic transit by a 5-HT3 antagonist in subjects with diarrhea-predominant irritable bowel syndrome.

OBJECTIVE: To evaluate the influence of gender on the effect of a 5-HT3 antagonist, alosetron, 1 mg b.i.d., on GI and colonic transit in D-IBS. METHODS: Thirty patients (15 male, 15 female) with D-IBS received 1 mg b.i.d. alosetron for 6 wk. Transit was measured by scintigraphy at baseline and at the end of treatment. RESULTS: Alosetron, 1 mg b.i.d., significantly retarded small bowel and, proximal and overall colonic transit in the 30 patients with D-IBS. The effect of alosetron on the primary endpoint, colonic geometric center at 24 h, was significantly greater in females than in males (p < 0.05). However, two females showed no slowing of colonic transit on treatment. Among male patients, two of 15 had a slowing of colonic transit at 24 h that was greater than the mean change in female patients, suggesting responsiveness to alosetron among a subgroup of males. CONCLUSION: A 5-HT3 antagonist, alosetron, significantly retards small intestinal and colonic transit in diarrhea-predominant IBS patients, with significantly greater female to male responsiveness. Gender partly contributes to differences in the serotonergic control of intestinal and colonic transit in patients with D-IBS.

Adult↗
PubMed2001

Comparative tissue distribution of the processing enzymes "prohormone thiol protease," and prohormone convertases 1 and 2, in human PTHrP-producing cell lines and mammalian neuroendocrine tissues.

Peptide hormones are generated by proteolytic processing of their respective protein precursors by several prohormone processing proteases. The peptide hormone PTHrP is widely expressed in normal and malignant tissues, where proPTHrP undergoes proteolytic processing to generate PTHrP peptides with distinct biological actions. In this study, the tissue distribution of the prohormone processing enzymes PTP, PC1, and PC2 were compared by immunohistochemistry in human PTHrP-producing cancer cell lines, and in mammalian neuroendocrine and other tissues from rat and bovine that contain peptide hormones. PTP, PC1, and PC2 were prominently expressed in PTHrP-expressing human cancer cell lines originating from tumors of the breast, lung, prostate, as well as lymphoma. These processing enzymes also showed significant expression in normal mammalian neuroendocrine tissues from bovine and rat, including pituitary, hypothalamus, adrenal medulla, pancreas, and other tissues. Most neuroendocrine tissues contained prominent levels of at least two of the three processing enzymes examined, and all tissues contained at least one of these three enzymes. Differential expression of processing enzyme proteins was also demonstrated by Western blots. The differential expression of PTP, PC1, and PC2 observed in certain cancer and normal neuroendocrine cell types postulates selective roles for these processing enzymes in different tissues for generating biologically active peptide hormones. These results support the importance of these processing enzymes in their hypothesized roles in prohormone processing.

Adrenal Medulla↗
PubMed2001

Development and current functioning in adolescents with Asperger syndrome: a comparative study.

Adolescents with Asperger syndrome (AS: without delay in speech development, diagnosed according to ICD-10 clinical criteria) were compared with a group with high-functioning autism (HFA: all with delayed speech development), and a group with conduct disorder (CD). Family and genetic studies suggest that Asperger syndrome and autism form part of the same spectrum, whereas the social impairments in conduct disorder are assumed to have different origins. The aims were to explore the relationships between early speech development and other aspects of functioning in autistic disorders, and to compare autistic and nonautistic social impairments. Early and current behaviour and IQ profiles were investigated. The CD group were clearly different from both the AS and HFA groups. The AS group tended to have less severe early behavioural abnormalities than the HFA group, and were unlikely to have speech abnormalities, but other communicative, social, and restricted/ stereotyped behavioural difficulties were largely of a similar pattern to the abnormalities in the HFA group. Eighty per cent of the AS group met criteria for autism on the diagnostic algorithm associated with the Autism Diagnostic Interview-Revised. By adolescence, the AS group were reported to be as abnormal as the HFA group but in structured 1:1 interaction their conversation was better. IQ profile in the AS group showed relative strength on verbal measures, unlike the HFA group, but relatively good performance on the Block Design subtest of the WISC/WAIS was a feature of both the AS and HFA groups. The results indicate closely similar behavioural manifestations may arise by adolescence despite differences in speech development. Follow-up studies and further family investigations will be required to clarify the origins of these and other patterns of autistic development.

Adolescent↗
PubMed2000

Cartoon characters as tobacco warning labels.

BACKGROUND: Multiple studies have indicated that the Joe Camel advertising campaign has been successful in marketing tobacco to children and adolescents, whereas other studies have reported that current tobacco warning messages are ineffective. OBJECTIVE: To determine the importance and believability of familiar and novel tobacco warning messages with and without cartoons that were modeled after Joe Camel. DESIGN: Children and adolescents (N = 580) in Chicago, Ill, public schools were surveyed to determine the believability and importance of 3 cartoon tobacco warnings modeled after Joe Camel developed with the messages "Smoking Causes Lung Cancer, Heart Disease, Emphysema, and May Complicate Pregnancy" or "Smoking Kills" and the same 2 messages without cartoons. RESULTS: Respondents rated all 3 cartoons significantly more believable than the plain condition regardless of the message (P<.05). Furthermore, respondents rated the "Smoking Causes Lung Cancer, Heart Disease, Emphysema, and May Complicate Pregnancy" warning significantly more believable and important than the "Smoking Kills" message across all 4 cartoon conditions (walrus, penguin, bear, and no cartoon) (P<.01). Selected demographic groups found particular cartoon and warning messages more believable and/or important than others. CONCLUSIONS: The finding that cartoon tobacco warnings are more believable than plain warnings suggests that it may be desirable to include cartoons in future tobacco warning labels. The lower ratings of believability and importance of the "Smoking Kills" warning is a concern because similar warnings have recently been implemented in at least 2 countries (Australia and Canada) and have been considered for implementation in the United States. Arch Pediatr Adolesc Med. 2000;154:1230-1236.

Adolescent↗
PubMed2000

Alpha(1)- and alpha(2)-adrenoceptor mediation in melanosome aggregation in cryptic patterning of Pleuronectes americanus.

The dark upper (ocular) surface of winter flounder (Pleuronectes americanus) possesses a chromatophore pattern, with cryptic dark bands and white spots, and a general background component, with melanophores under adrenergic neural control. In vitro responsiveness to the alpha-adrenoceptor agonists phenylephrine and clonidine and to the antagonists yohimbine and prazosin demonstrates that melanosome aggregation in this species is mediated through both alpha(1)- and alpha(2)-adrenoceptors, the alpha(2)-subtype being predominant in each pattern component. However, differences in the potency of agonists and antagonists indicate variability in the balance between the two receptors between pattern components. This paper demonstrates that it cannot be generalized that teleost melanophore alpha-adrenoceptors are universally of one subtype, and also that there is intraspecific variation in subtypes of these receptors associated with the flatfish cryptic patterning mechanism.

Adrenergic alpha-Agonists↗
PubMed2000

Social and psychiatric functioning in adolescents with Asperger syndrome compared with conduct disorder.

Lack of standardized phenotypic definition has made outcome studies of Asperger syndrome (AS) difficult to interpret. This paper reports psychosocial functioning in 20 male adolescents with AS, defined according to current ICD-10 criteria, and a comparison group of 20 male adolescents with severe conduct disorder. Subjects were gathered from clinical referral. Evaluation used standardized interviewer rated assessments of social functioning and psychiatric morbidity. The AS group showed severe impairments in practical social functioning despite good cognitive ability and lack of significant early language delay. High levels of anxiety and obsessional disorders were found in AS; depression, suicidal ideation, tempers, and defiance in both groups. Results are compared with those from other studies. Relevance to clinical ascertainment and treatment is discussed.

Adaptation, Psychological↗
PubMed2000

Effects of a serotonin 5-HT(4) receptor antagonist SB-207266 on gastrointestinal motor and sensory function in humans.

BACKGROUND: Serotonin 5-HT(4) receptors are located on enteric cholinergic neurones and may regulate peristalsis. 5-HT(4) receptors on primary afferent neurones have been postulated to modulate visceral sensation. While 5-HT(4) agonists are used as prokinetic agents, the physiological role of 5-HT(4) receptors in the human gut is unknown. AIMS: Our aim was to characterise the role of 5-HT(4) receptors in regulating gastrointestinal motor and sensory function in healthy subjects under baseline and stimulated conditions with a 5-HT(4) receptor antagonist. METHODS: Part A compared the effects of placebo to four doses of a 5-HT(4) receptor antagonist (SB-207266) on the cisapride mediated increase in plasma aldosterone (a 5-HT(4) mediated response) and orocaecal transit in 18 subjects. In part B, 52 healthy subjects received placebo, or 0.05, 0.5, or 5 mg of SB-207266 for 10-12 days; gastric, small bowel, and colonic transit were measured by scintigraphy on days 7-9, and fasting and postprandial colonic motor function, compliance, and sensation during distensions were assessed on day 12. RESULTS: Part A: 0.5, 5, and 20 mg doses of SB-207266 had significant and quantitatively similar effects, antagonising the cisapride mediated increase in plasma aldosterone and acceleration of orocaecal transit. Part B: SB-207266 tended to delay colonic transit (geometric centre of isotope at 24 (p=0.06) and 48 hours (p=0.08)), but did not have dose related effects on transit, fasting or postprandial colonic motor activity, compliance, or sensation. CONCLUSION: 5-HT(4) receptors are involved in the regulation of cisapride stimulated orocaecal transit; SB 207266 tends to modulate colonic transit but not sensory functions or compliance in healthy human subjects.

Adolescent↗
PubMed2000

Functional interactions between GTP cyclohydrolase I and tyrosine hydroxylase in Drosophila.

Tyrosine hydroxylase requires the regulatory cofactor, tetrahydrobiopterin, for catecholamine biosynthesis. Because guanosine triphosphate cyclohydrolase I is the rate limiting enzyme for the synthesis of this cofactor, it has a key role in catecholamine production. We show that GTP cyclohydrolase and tyrosine hydroxylase (TH) are co-localized in the Drosophila central nervous system. Mutations in the Punch locus, which encodes GTP cyclohydrolase, reduce TH activity; addition of cofactor to crude extracts could not fully rescue this activity in all mutant strains. The decrease in TH activity and the inability to increase it with added cofactor is not due to loss or decreased production of TH protein. We found that TH co-immunoprecipitated with GTP cyclohydrolase when wild type head extracts were incubated with anti-GTP cyclohydrolase antibody. We suggest that regulation of TH by its cofactor may require its association with GTP cyclohydrolase, and that the ability of GTP cyclohydrolase to associate with TH and its role in tetrahydrobiopterin synthesis may be separable functions of this enzyme. These results have important implications for understanding catecholamine-related neural diseases and designing strategies for gene therapy.

Alleles↗
PubMed1999

The effects of biofeedback on rectal sensation and distal colonic motility in patients with disorders of rectal evacuation: evidence of an inhibitory rectocolonic reflex in humans?

OBJECTIVE: Abnormalities of descending colon motility reported in a subset of patients with rectal evacuation disorders are consistent with a rectocolonic inhibitory reflex. Our aims were to evaluate distal colon motor function and rectal sensation in such patients and assess effects of biofeedback (BF) training on these functions. METHODS: Seven patients (five women, two men; mean age 36 yr) with rectal evacuation disorders were studied before and after 10-days biofeedback training; six healthy volunteers (five women, one man; mean age 30 yr) were studied once. Colonic compliance, motility, sensation thresholds, and perception scores during standardized rectal distentions were measured using two barostat-manometry assemblies inserted into the cleansed colon with the aid of flexible sigmoidoscopy. RESULTS: Sigmoid compliance, fasting, and postprandial motility index, and perception thresholds were similar in controls and patients before and after biofeedback training. Postprandial sigmoid tone tended (p = 0.09) to be lower in patients than controls; after biofeedback, postprandial tone was comparable to that in controls. Rectal urgency scores at 24 mm Hg distention were greater in patients than in controls (p = 0.02 for both). After biofeedback, there were trends for lower perceptions of urgency to defecate (7.6 +/- 1.1 cm pre- vs 5.3 +/- 1.5 post-; p = 0.04) at 24 mm Hg; conversely, gas sensation at 12 mm Hg was higher (1.2 +/- 0.5 cm pre- vs 3.3 +/- 0.6 post-; p = 0.05). CONCLUSIONS: Normalization of rectal evacuation and postprandial sigmoid tone in patients with evacuation disorders by biofeedback training supports the presence of a rectocolonic inhibitory reflex. Effect of biofeedback on rectal sensation in these patients requires further study.

Adult↗
PubMed1999

Pain control and cultural norms and expectations after closed femoral shaft fractures.

The purpose of this observation-cohort survey study was to compare the analgesia given and satisfaction with analgesia after a uniform orthopedic injury and operation in culturally disparate settings. Twenty-five patients with isolated closed femoral shaft fractures treated with intramedullary rod fixation within 1 week of injury were retrospectively evaluated at two urban hospitals in the United States. They were compared with a matched group from three urban hospitals in Vietnam (two in Hanoi and one in Ho Chi Minh City [Saigon]). Ages and sex did not differ significantly between the two groups. The mean weight of the Vietnamese group was significantly less than that of the US group (58 vs. 81 kg). During the 14 days following injury, the Vietnamese and American groups were given a mean of 0.9 mg/kg per day versus 30.2 mg/kg per day of morphine equivalent units, respectively. Two (8%) of the Vietnamese group felt their pain control had been inadequate, versus 20 (80%) of the US group. Similarly, 2 (8%) of the US group and 7 (28%) of the Vietnamese group felt they had received "too much" pain medication. Mean heart rates during the first 5 days after surgery were not significantly different in the two groups. Only 4% of the US group felt they had had an accurate impression of how much a femur fracture would hurt prior to the injury, whereas 76% of Vietnamese patients responded that they imagined such an injury would be approximately as painful as it was. Results were similar for preconceptions of pain as a result of surgery and during the postoperative period. More than 50% of patients from the US group felt there must be some explanation other than the femur fracture to explain the severity of their pain, such as infection, missed injury, hardware failure, or inappropriate medical care. Despite much higher administration of narcotic analgesia, American patients with femoral shaft fractures were much more dissatisfied with their analgesic results. In assessing the recommended dosing for "adequate analgesia" and "analgesic requirements," determinations may depend less upon tissue injury than upon cultural norms and patient expectations.

Adult↗
PubMed1998

The Prenatal Psychosocial Profile: a research and clinical tool.

This report summarizes five studies of culturally diverse women who were administered the Prenatal Psychosocial Profile (PPP). These data from 3,444 rural and urban women of all childbearing ages support the validity and reliability of the PPP as a measure of stress, support from partner, and support from others. The self-esteem scale is a valid and reliable measure for Caucasian and African American women. However, the cultural appropriateness of the self-esteem scale for Native American women is questionable, and it is neither valid nor culturally appropriate for traditional Hispanic women. The mean scores for stress, partner support, and other support were similar for all groups except for scales expected to differ by sample groups. Thus, suggested cutoff scores should be useful for screening purposes. The PPP provides a brief, yet comprehensive profile that is accepted by participants and useful to researchers and clinicians.

Adolescent↗
PubMed1998

Parathyroid hormone-related proteins is abundant in osteoarthritic cartilage, and the parathyroid hormone-related protein 1-173 isoform is selectively induced by transforming growth factor beta in articular chondrocytes and suppresses generation of extracellular inorganic pyrophosphate.

OBJECTIVE: Parathyroid hormone-related protein (PTHrP) is a major, locally expressed regulator of growth cartilage chondrocyte proliferation, differentiation, synthetic function, and mineralization. Because mechanisms that limit cartilage chondrocytes from maturing and mineralizing are diminished in osteoarthritis (OA), we studied PTHrP expression by articular chondrocytes. METHODS: PTHrP was studied in normal knee cartilage samples and cultured articular chondrocytes, and in cartilage specimens from knees with advanced OA, obtained at the time of joint replacement. RESULTS: PTHrP was more abundant in OA than in normal human knee articular cartilage. Both demonstrated PTH/PTHrP receptor expression. PTHrP 1-173, one of three alternatively spliced PTHrP isoforms, was exclusively expressed and induced by transforming growth factor beta in cultured chondrocytes. Chondrocytes mainly used the GC-rich P2 alternative promoter to express PTHrP messenger RNA. Inhibition by PTHrP 1-173, but not by PTHrP 1-146 or PTHrP 1-87, of inorganic pyrophosphate (PPi) elaboration suggested selective functional properties of the 1-173 isoform. Exposure to a neutralizing antibody to PTHrP increased PPi elaboration by articular chondrocytes. CONCLUSION: Increased expression of PTHrP, including the 1-173 isoform, has the potential to contribute to the pathologic differentiated functions of chondrocytes, including mineralization, in OA.

Adult↗
PubMed1998

Structural interactions between actin, tropomyosin, caldesmon and calcium binding protein and the regulation of smooth muscle thin filaments.

The basic structure and functional properties of smooth muscle thin filaments were established about 10 years ago. Since then we and others have been working on the details of how tropomyosin, caldesmon and the Ca(2+)-binding protein regulate actin interaction with myosin. Our work has tended to emphasize the similarities between caldesmon and troponin function whilst others have been more concerned with the differences. The need to resolve the resulting differences has stimulated us to find new and more direct ways of investigating the mechanism of thin filament regulation. In recent years an apparent divergence has opened up between functional measurements, which indicate an allosteric-cooperative regulatory mechanism in which caldesmon and Ca(2+)-binding protein control actin-tropomyosin state in the same way as troponin, and structural measurements which show thin filament structures unlike striated muscle thin filaments. The challenge is to interpret function in terms of structure. We have combined functional studies with expression and mutagenesis of caldesmon and with structural methods including X-ray crystalography of tropomyosin-caldesmon crystals, electron microscopy and helical reconstruction of actin-tropomyosin-caldesmon complexes and high resolution nuclear magnetic resonance spectroscopy of the C-terminus of caldesmon in interaction with actin and calmodulin. We have used this information to propose a structural mechanism for caldesmon regulation of the smooth muscle thin filament.

Actins↗
PubMed1998

The effects of nursing case management on the utilization of prenatal care by Mexican-Americans in rural Oregon.

This quasi-experimental, retrospective study used birth certificate and medical record data to evaluate the effectiveness of the Rural Oregon Minority Prenatal Program (ROMPP) in improving patterns of prenatal care utilization by rural-dwelling, low-income, Mexican-American women at risk of poor pregnancy outcomes. The ROMPP intervention provided nursing case management services and peer outreach to pregnant Mexican-American women in a rural Oregon community. The intervention group had more prenatal visits in months 2, 3, 4, 5, 6, and 7 than the comparison group (P < 0.05). The intervention group had a similar number of emergency room (ER) visits, but had more respiratory diagnoses and fewer urinary tract infections. ROMPP women had more inpatient admissions and longer lengths of stay. No differences were found in the initiation of prenatal care or the total number of prenatal care visits, nor in the timing of screening serum glucose tests. The intervention should be expanded to address the persistent attitudinal, financial, transportation and language barriers to adequate prenatal care. Nurses should increase their cultural competency and sharpen their clinical focus on advocacy, marketing, facilitation of relationships between community groups, and community organizing.

Adolescent↗
PubMed1998

Bone morphogenetic proteins and bFGF exert opposing regulatory effects on PTHrP expression and inorganic pyrophosphate elaboration in immortalized murine endochondral hypertrophic chondrocytes (MCT cells).

A fundamental question in endochondral development is why the expression of parathyroid hormone-related protein (PTHrP), which inhibits chondrocyte maturation and mineralization, becomes attenuated at the stage of chondrocyte hypertrophy. To address this question, we used clonal, phenotypically stable SV40-immortalized murine endochondral chondrocytes that express a growth-arrested hypertrophic phenotype in culture (MCT cells). Addition of individual cytokines to the medium of MCT cells revealed that bone morphogenetic protein (BMP)-6, which commits chondrocytes to hypertrophy, markedly inhibited PTHrP production. This activity was shared by three other osteogenic bone morphogenetic proteins (BMP-2, BMP-4, and BMP-7) and by transforming growth factor beta (TGF-beta), which all inhibited the level of PTHrP mRNA. In contrast, basic fibroblast growth factor (bFGF), an inhibitor of chondrocyte maturation to hypertrophy, induced PTHrP in MCT cells and antagonized the effects of BMP-2, BMP-4, BMP-6, and BMP-7 and TGF-beta on PTHrP expression. Opposing effects of bFGF and BMPs also were exerted on the elaboration of inorganic pyrophosphatase (PPi), which regulates the ability of hypertrophic chondrocytes to mineralize the matrix. Specifically, BMP-2 and BMP-4, but not BMP-6 and BMP-7, shared the ability of TGF-beta to induce PPi release, and this activity was inhibited by bFGF in MCT cells. Our results suggest that effects on PTHrP expression could contribute to the ability of BMP-6 to promote chondrocyte maturation. BMPs and bFGF exert opposing effects on more than one function in immortalized hypertrophic chondrocytes. Thus, the normal decrease in bFGF responsiveness that accompanies chondrocyte hypertrophy may function in part by removing the potential for bFGF to induce PTHrP expression and to oppose the effects of BMPs. MCT cells may be useful in further understanding the mechanisms regulating the differentiation and function of hypertrophic chondrocytes.

Animals↗
PubMed1998

Reasons for quitting and smoking temptation among adolescent smokers: gender differences.

Adolescent cigarette smokers from randomly selected classrooms from 24 California and Illinois high schools were assessed regarding their interest in cessation, reasons for quitting, and smoking temptation circumstances. These data were analyzed by gender. Males and females were not found to differ in quit stage or perceived likelihood of ever quitting smoking, although males reported being somewhat more likely to have ever tried to quit in the past. The associations of reasons for quitting were not found to vary by gender in most comparisons. On the other hand, the associations of smoking temptation circumstances with gender showed that a greater percentage of females than males reported more circumstances that would make them tempted to smoke. Smoking cigarettes to regulate one's affective states, and to avoid nicotine withdrawal, may be functions of smoking that impede efforts at quitting, particularly among adolescent females.

Adolescent↗