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Biomedical subjects

D Young

Publications and source records attributed to D Young.

At least 181 records · Page 10Linked to original sources
PubMed1998

Temporal relationships between hormonal and hemodynamic changes in early human pregnancy.

BACKGROUND: The systemic hemodynamic profile of human pregnancy is characterized by a decrease in mean arterial pressure, a rise in cardiac output and plasma volume in association with an increase in renal plasma flow and glomerular filtration rate. The factors and the time course responsible for the initial hemodynamic changes seen in human pregnancy have not been completely documented. We hypothesize that systemic and renal hemodynamic changes occur early, prior to the presence of the fetal-placental unit. METHODS: Thirteen women were studied prior to and immediately following conception in identical fashion at gestational weeks 6, 8, 10, 12, 24 and 36. Individuals underwent mean arterial pressure, cardiac output, inulin and PAH clearance determinations. RESULTS: Mean arterial pressure decreased by six weeks gestation (mid follicular 81.5 +/- 2.6 vs. six weeks 68.7 +/- 2.0 mm tig, P < 0.001) in association with a significant increase in cardiac output, a decrease in systemic vascular resistance and an increase in plasma volume. Renal plasma flow and glomerular filtration rate increased by six weeks gestation. Plasma renin activity and aldosterone concentration increased significantly by six weeks, whereas norepinephrine levels did not change throughout pregnancy. Atrial natriuretic peptide levels increased later, at 12 weeks gestation. Plasma cGMP levels decreased and cGMP clearance increased by six and eight weeks, respectively. CONCLUSIONS: Peripheral vasodilation occurs early in pregnancy prior to full placentation in association with renal vasodilation and activation of the renin-angiotensin-aldosterone system. Plasma volume expansion occurs early, followed later by increases in ANP concentration, suggesting that ANP increases in response to changes in intravasular volume.

Adult↗
PubMed1998

The relationship between objective life status and subjective life satisfaction with quality of life.

A locally developed quality of life inventory was used to examine the relationship between objective life status and subjective satisfaction with quality of life in 8,550 participants from Hunan, China. The inventory included 112 items in 4 dimensions-physical health, psychological health, social functional status, and living conditions. Objective life status was the principal factor affecting subjective satisfaction, but discrepancies were found in some participants, especially when objective status was at the extremes of the distribution. Young, urban, or more educated participants with higher scores on objective status often had lower subjective satisfaction scores in spite of comparatively high objective status scores. Participants who ranked lower on objective status (old, rural, or less educated people) sometimes ranked higher in subjective satisfaction. Scores for subjective satisfaction always showed a normal distribution, whatever the objective satisfaction of the population. Divergence between individual objective status and subjective satisfaction was associated with hierarchy of life needs and the reference standards used for the comparison.

Adult↗
PubMed1998

Postovulatory ageing of mouse oocytes in vivo and premature centromere separation and aneuploidy.

Two paramount observations exist regarding aneuploidy in human oocytes: its association with maternal age and its more frequent occurrence during meiosis I. Numerous experimental studies have shown that fertilization of postovulatory aged oocytes is coupled with reproductive failure and cytogenetic aberrations in embryos. However, the basic cytogenetic defect(s) of aged oocytes that causes these abnormalities has not been adequately described. The objective of this study was to test the hypothesis that postovulatory oocyte ageing results in increased frequencies of premature centromere separation (PCS) in metaphase II (MII) oocytes and aneuploidy in zygotes. MII oocytes and one-cell zygotes were collected from superovulated mice at different times after ovulation and fertilization. Chromosomes were C-banded and analyzed for structural and numerical aberrations. The frequencies of PCS in oocytes significantly (p < 0.01) increased with time postovulation: 15 h (15 of 529, 2.8%), 20 h (82 of 627, 13.1%), and 25 h (118 of 502, 23.5%). In zygotes, the frequencies of hyperploidy significantly (p < 0.01) increased with time post-fertilization: 0-4 h (0 of 260), 4-8 h (5 of 212, 2.4%), and 8-12 h (8 of 262, 3.1%). These data support the hypothesis that postovulatory ageing results in elevated levels of PCS in oocytes and of aneuploidy in zygotes. The link between PCS and aneuploidy may be random segregation of sister chromatids during anaphase II.

Aneuploidy↗
PubMed1998

Cognitive-behavioral treatment of school-refusing children: a controlled evaluation.

OBJECTIVE: To evaluate the efficacy of a 4-week cognitive-behavioral treatment program for children who refuse to go to school. METHOD: Thirty-four school-refusing children (aged 5 to 15 years) were randomly assigned to a cognitive-behavioral treatment condition or a waiting-list control condition. Treatment consisted of individual child cognitive-behavioral therapy plus parent/teacher training in child behavior management skills. Measures taken before and after treatment included school attendance, child self-report of emotional distress and coping, caregiver reports on emotional and behavioral problems, and clinician ratings of global functioning. RESULTS: Relative to waiting-list controls, children who received cognitive-behavioral therapy exhibited a significant improvement in school attendance. These children also improved on self-reports of fear, anxiety, depression, and coping. Significant improvements also occurred in relation to caregiver reports and clinician ratings. Maintenance of therapeutic gains was demonstrated at a 3-month follow-up assessment. CONCLUSIONS: Cognitive-behavioral treatment of school refusal was efficacious and acceptable. The relative contributions of child therapy and parent/teacher training require further study.

Adolescent↗
PubMed1998

Taoistic cognitive psychotherapy for neurotic patients: a preliminary clinical trial.

Taoistic cognitive psychotherapy is a cognitive therapy based on Taostic philosophy of life and health. The present preliminary study aims to test clinical significance of the Taoistic cognitive psychotherapy, indicates that type A behavior patterns distorted values and psychopathologies can be improved after a short period (4 weeks) of Taoistic cognitive psychotherapy. The theoretical basis of this psychotherapy is also briefly introduced.

Adult↗
PubMed1998

Psychoactive substance use in three sites in China: gender differences and related factors.

One year prevalence rates for psychoactive substance use are reported based on community surveys performed in three sites in China: Hunan, Heilongjiang and Jiangsu. The data were gathered on more than 14,000 respondents (15-65 years old). The drinking rates were from 58.3 to 82.6% for men and from 16.3 to 31.4% for women. Smoking rates range from 64.9 to 68.1% for men and from 0.1 to 20.5% for women. Most drinkers were light users and most smokers were heavy users. Illicit drug use was observed at Hunan. Regarding frequency and quantity of psychoactive substance use, women are lighter consumers than their male counterparts except for use of minor tranquilizers and analgesics. The psychosocial factors related to drinking and smoking were also investigated in this study.

Adolescent↗
PubMed1998

Does an early postnatal check-up improve maternal health: results from a randomised trial in Australian general practice.

OBJECTIVES: To investigate whether a visit to a general practitioner one week after discharge results in less depression, increased breastfeeding rates, improved patient wellbeing, fewer physical problems and greater satisfaction with general practice care than the traditional six week postnatal check-up. DESIGN: A randomised controlled trial. SETTING: Rural and metropolitan Victoria, Australia. Population Women giving birth at one rural and one metropolitan hospital between February and December 1995 inclusive. METHODS: All women received a letter and appointment date to see a general practitioner for a check-up: the intervention group for one week after hospital discharge, the control group for six weeks after birth. A mail-out survey was conducted at three and six months after birth, including Edinburgh Postnatal Depression Scale and Short Form 36. RESULTS: 1017/1407 (72.3%) women giving birth at participating hospitals were eligible for the trial: 683 (67.2%) gave informed consent. The average response rate to postal follow up at three and six months was 67.5%. No significant differences were found between the groups in: Edinburgh Postnatal Depression and Short Form 36 scores; number of problems; breastfeeding rates; or satisfaction with general practitioner care. Women in the intervention group were less likely to attend for their check-up (76.4% vs 88.4%; P = 0.001), more likely to discuss labour and birth at their check-up (OR= 1.77, 95% CI 1.17-2.68), less likely to have a vaginal examination (OR = 0.51; 95%, CI 0.34-0.77) or pap smear (OR = 0.34; 95% CI = 0.22-0.52) at their check; more likely to report difficulties with low milk supply (OR= 1.72; 95% CI = 1.12-2.66) and adjusting to the demands of a new baby (OR = 1.76; 95% CI 1.13 2.74), more likely to talk to a general practitioner about their baby (68.2% vs 58.0%; P=0.02) and less likely to consult a hospital doctor about their baby (7.3% vs 14.0%, P = 0.02). CONCLUSIONS: To make clinically important improvements in maternal health more is required than early postnatal review.

Breast Feeding↗
PubMed1998

The impact of formulation and process changes on in vitro dissolution and the bioequivalence of piroxicam capsules.

The purpose of this research was to determine the effect of major compositional changes on the bioavailability of piroxicam from immediate-release formulations filled in hard gelatin capsules. The capsules were manufactured according to a 2(5-1) + star point (resolution V) experimental design to investigate the effects of sodium lauryl sulfate level, magnesium stearate level, lactose/microcrystalline cellulose ratio, piroxicam particle size, and lubricant blending time. Sodium lauryl sulfate level, lactose level, and piroxicam particle size were the most important main effects affecting dissolution. Lubricant level and lubricant blending time were either not significant (5% level) or were among the lowest ranking of factors affecting dissolution in standardized pareto analysis. Three of these formulations exhibiting slow, medium, and fast dissolution were compared to a single lot of the Innovator (commercial) product in a small bioavailability study. The slow formulation did not meet the USP dissolution specification for piroxicam capsules. Compositionally, the experimental formulations represented major changes in piroxicam particle size, level of filler, and level of sodium lauryl sulfate. Sixteen healthy volunteers received each formulation (20 mg) in a four-way crossover design. The three Maryland manufactured formulations were bioequivalent with the commercial product and were also bioequivalent among themselves. The major changes incorporated into these formulations did not result in major differences in bioavailability. The dissolution profiles which discriminated between the formulations in vitro did not accurately represent the in vivo bioavailability results. The results of this study are part of the research database that supports SUPAC-IR, an FDA guidance that provides relaxed testing and filing requirements for scale-up and post-approval changes to immediate-release oral solid dosage forms.

Adult↗
PubMed1998

Childhood tuberculosis: advances in immunopathogenesis, treatment and prevention.

Tuberculosis in childhood is an important cause of mortality worldwide. The disease is difficult to diagnose and the underlying immune mechanisms are poorly understood. Advances in the application of molecular genetic tools, as illustrated by the recent completion of the genome sequence of Mycobacterium tuberculosis, provide opportunities for the development of improved diagnostic tools and vaccines for tuberculosis. It is important that research efforts in this area should include consideration of the unique problems and possibilities related to the control of tuberculosis in children.

Journal Article↗
PubMed1998

Effects of phenobarbital on stereoselective metabolism of ifosfamide in rats.

Plasma and urinary levels of ifosfamide (IF) enantiomers and their metabolites 2-dechloroethylifosfamide, 3-dechloroethylifosfamide, 4-hydroxyifosfamide, and isophosphoramide mustard were determined for control and phenobarbital-treated male Sprague-Dawley rats by using pseudoracemates and GC/MS and stable-isotope dilution analytical methods. For the control rats, the mean AUC for (S)-IF in plasma was greater than that for (R)-IF (R/S AUC ratio, 0.78) and the mean half-life of 41.8 min for (S)-IF was slightly longer than that of 34.3 min for (R)-IF. Phenobarbital pretreatment significantly decreased the AUC values for (R)-IF and (S)-IF, to 21 and 30% of the control values, respectively, and shortened plasma half-lives for both enantiomers [half-life for (R)-IF, 19.8 min; half-life for (S)-IF, 19.4 min]. The urinary excretion values for (R)-IF and (S)-IF were decreased to 41 and 30% of the control values, respectively. The overall amounts of the metabolites in urine were concomitantly increased. Additionally, there were significant reversals in both the R/S AUC ratio and the urinary excretion of 3-dechloroethylifosfamide. Moreover, the enantioselectivity for the generation of 4-hydroxyifosfamide and isophosphoramide mustard disappeared after phenobarbital treatment. These results strongly suggested that the 4-hydroxylation and dechloroethylation of IF enantiomers were mediated by different P450 isozymes or the same isozyme with different stereochemical selectivities.

Animals↗
PubMed1998

Involvement of Victorian general practitioners in obstetric and postnatal care.

OBJECTIVE: To assess the current nature and extent of general practice (obstetric) involvement and the effect of gender on the provision of maternity care in Victoria. METHOD: A postal survey to a community derived sample of 1104 Victorian general practitioners (with oversampling of female GPs) in August 1994 with hierarchical data analysis techniques used to account for the clustered (divisional) nature of the sampling frame. RESULTS: A 70% response rate was achieved (715 out of an eligible sample of 1022). Three hundred and sixty-two (45.6%) GPs were providing shared care, 127 (17.7%) intrapartum care and 656 (92%) were involved in seeing women for their routine 6 week postnatal checkup. Male and female GPs were equally qualified and as likely to be vocationally registered (90% vs 92%). Female GPs were less likely than male GPs (11% vs 25%) to be involved in intrapartum care (OR = 0.4, 95% CI = 0.3-.06). Female GPs were more likely than male GPs (50% vs 41%) to be involved in shared care (OR = 1.4, 95% CI = 1.01-2.0), and postnatal care (OR = 3.7, 95% CI = 2.5-5.4). Provincial city (population > 15,000) GPs were more likely to provide shared care than other GPs. Fifty-two per cent of GPs providing shared care held a Diploma of Obstetrics. After accounting for the gender differences associated with practice location, rural GPs were more likely to provide intrapartum care (OR = 10.6, 95% CI = 3.5-32.4). CONCLUSION: General practitioners play an important role in all facets of maternity care. Female and male GPs differ in their type of obstetric practice. If GPs are to maintain an intrapartum role, prompt action is required to increase the number of GPs involved in intrapartum care. The training requirements for shared care should be reviewed and a more suitable postnatal care curriculum should be developed.

Adult↗
PubMed1998

Collagen shield delivery of tobramycin to the human eye.

PURPOSE: The purpose of this study was to determine the ocular penetration of tobramycin into the anterior chamber of the human eye when delivered by a pre-soaked collagen shield. METHODS: We conducted a prospective, randomized study of 32 patients undergoing cataract surgery. The subjects were divided into two groups. The first group received three preoperative drops of commercially available combination tobramycin-dexamethasone drops at 15 minute intervals. In the second group, a collagen shield soaked in the same medication was applied to the eye prior to surgery. At the beginning of surgery, the aqueous humor was extracted for analysis. RESULTS: The samples from 11 patients could not be analyzed due to an insufficient aqueous sample. Of the remaining 21 patients, the mean aqueous concentration was 0.026 microgram/mL (range: 0.0-0.09) in the drops group and 0.024 microgram/mL (range: 0.04-0.8 microgram/mL) in the shield group. This difference was not statistically significant. The aqueous concentration in both groups did not approach the minimum inhibitory concentration (4 micrograms/mL) for common ocular pathogens. No adverse effects related to the use of collagen shields occurred. CONCLUSIONS: Perioperative use of a pre-soaked collagen shield utilizing a commercially available preparation of tobramycin-dexamethasone combination drops appears safe. However, the use of this system to prevent endophthalmitis is not warranted based on the concentrations obtained from the aqueous humor.

Administration, Topical↗
PubMed1998

Candidate hematopoietic stem cells from fetal tissues, umbilical cord blood vs. adult bone marrow and mobilized peripheral blood.

As part of our ongoing effort to identify a rich source of pluripotent progenitor cells for transplantation and gene therapy, we cultured single-sorted CD34+ subpopulations from different human hematopoietic tissues to assess the relationship between immunophenotype expression and functional characteristics. In combination with index sorting, single cell culture permits precise assessment of the colony efficiency (CE), growth characteristics, and replating potential (RP) of each individual phenotype without interference from other cell types. CD34+ cells from fetal liver (FL), fetal bone marrow (FBM), umbilical cord blood (UCB), adult BM (ABM), and mobilized peripheral blood (MPB) were sorted and cultured as single cells according to the coexpression of CD38. With the exception of FL, higher CEs were found among CD34+/CD38+ cells vs. CD34+/CD38- cells from the same cell source. However, colonies with dispersed growth pattern (DGP) and mixed growth pattern (MGP) were found predominantly in the CD34+/CD38- subsets. We next examined the functional characteristics of CD34+ subsets defined by three-color analysis and coexpression of CD38 and HLA-DR or CD38 and CDw90 (Thy-1). Using the combination CD34, CD38, and HLA-DR, the highest CEs, the highest percentages of colonies with DGP/MGP and the maximum RP were found in the CD34+/CD38-/HLA-DR+ subset among samples from FL, FBM, and UCB. The CEs and percentages of colonies with DGP/MGP of single-sorted CD34+/CD38-/HLA-DR+ cells were 72.7+/-11.8% (mean +/- standard deviation) and 20.1+/-10.4%, respectively, in FL; 60.9+/-11.1% and 11.5+/-5.4% in FBM; 57.0+/-16.5% and 24.1+/-7.3% in UCB; 27.2+/-12.8% and 9.0+/-4.9% in MPB, and 9.6+/-7.8% and 4.6+/-3.2% in ABM. Using the combination CD34, CD38, and CDw90(Thy-1), the subset with the highest CEs and highest percentages of colonies with DGP/MGP was found to be CD34+/CD38-/CDw90- in FL and FBM, but colonies with high RP were distributed evenly among CDw90+ and CDw90- subsets derived from FL, FBM, UCB, or MPB. We conclude that the CD34+/CD38-/HLA-DR+ subset contained the highest number of candidate stem cells among the various immunophenotypes, and that FL contained the highest concentration of CD34+ cells (11.4+/-7.5%) and the highest level of CD34+/CD38-/HLA-DR+ subsets (34.7+/-8.2%) among cells from various ontogenic age. Our estimate of candidate stem cells using single cell suspension culture correlated with that obtained by single cell long-term culture-initiating cells. CD34+/CD38-/HLA-DR+ cells from FL appear to represent the best targets for ex vivo stem cell expansion and genetic manipulation.

ADP-ribosyl Cyclase↗
PubMed1998

The role of the general practitioner in postnatal care: a survey from Australian general practice.

BACKGROUND: Despite the practice of routine postnatal check-ups, many women experience problems in the months after childbirth. General practitioners (GPs) are involved in routine postnatal care, yet little research has been undertaken to explore this role. AIM: To report the views of Australian GPs as to what physical examination and discussion should take place at the routine six week postnatal check-up and to determine the influence of gender on the approach to the check-up. METHOD: Postal survey of 1104 Australian GPs, yielding an eligible sample of 1022. RESULTS: A total of 715/1022 (70%) usable surveys returned. Over 65% of GPs recommend routine examination of the abdomen, blood pressure, perineum, vagina, pelvic floor, and breasts at the six week check-up. Fewer than a half the sample believed that physical problems (urine and bowel symptoms, back problems), sexual issues, relationship and parenting issues should be routinely discussed. After controlling for age, practice location, obstetric practice, and qualifications, the sex of the GP remains an important factor influencing the GP's approach to postnatal care. Female GPs are three times more likely to believe that maternal feelings should be discussed routinely and about twice as likely to believe that infant sleeping/behaviour, maternal sleeping/diet/tiredness, coping with other children, relationship with partner, and household work should form part of the routine discussion with all recent mothers. CONCLUSIONS: Sex of practitioner and older age (60 years or more) are the two most important influences on a GP's approach to postnatal care. This study indicates a need for GPs to shift their focus from routine examination to indicated examination to allow more time to discuss common postnatal problems.

Adult↗
PubMed1997

Health promotion and older people: a qualitative study of general practitioners' views.

OBJECTIVES: To explore general practitioners' (GPs') beliefs about health promotion for older people and attitudes towards educational strategies likely to improve practice in this area. DESIGN AND SETTING: Four discussion groups, each lasting one and a half hours, completed in Melbourne, Australia in August and September 1995. Interviews were transcribed verbatim and analysed for major themes. PARTICIPANTS: A convenience sample of 20 GPs took part; 11 university affiliates, four participant contacts and five GPs from telephone book listings. RESULTS: GPs' perceptions of their health promotion practice varied from "integrated into all medical care", to "something separate from usual practice". Positive views of older people contrasted with ageist views, with a few GPs expressing a nihilistic approach to medical care of older people. Regardless of the GPs' attitudes, lack of time and reimbursement disincentives were perceived to limit preventive practice and the potential impact of health promotion interventions. GPs felt overwhelmed with their workloads, and initial reactions to the idea of any "new" program were negative. Reactions to educational strategies varied, with choice and relevance to ease of practice being important for GP participation. CONCLUSIONS: GPs differ in their views of health promotion and in their approaches to its delivery for older people. Educational programs are often viewed negatively, but if they offer the opportunity to save time, increased participation may be more likely.

Aged↗