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Biomedical subjects

P Smith

Publications and source records attributed to P Smith.

At least 325 records · Page 18Linked to original sources
PubMed1997

Ovarian morphology and endocrine characteristics of female sheep fetuses that are heterozygous or homozygous for the inverdale prolificacy gene (fecX1).

The Inverdale gene (fecX1), located on the X chromosome, is a major gene affecting the ovulation rate of sheep. At each ovulation, ewes heterozygous (I+) for the fecX1 gene ovulate, on average, one more egg than noncarriers (++), whereas ewes that are homozygous (II) for this gene are infertile and have "streak" ovaries. Since formation of the ovary occurs in fetal life, it is possible that the fecX1 gene influences ovarian development before birth. The aims of this study were to examine the effects of the fecX1 gene on germ cell development, follicular formation and growth, and plasma gonadotropin concentrations at 5 different days of gestation (i.e., Days 40, 90, 105, 120, and 135) and also in adult life. The results suggest that one copy of the X-linked mutation in female fetuses leads to a retardation of germ cell development at Days 40 and 90 of gestation. However, from Day 105 of gestation, follicular formation and growth appear normal. By contrast, in females with two copies of the X-linked mutation, germ cell development and follicular formation appear normal, but thereafter follicular growth from the primary stage of development is impaired. During fetal life the plasma concentrations of FSH and LH, although not measurable at Day 40, were similar between all the genotypes at Day 105, 120, and 135 of gestation. The only exception was for LH at Day 90 in the I+ and II animals: in ewes with these genotypes the plasma concentrations of LH were similar but significantly lower (p < 0.01) than in the ++ genotype. In adult animals the plasma concentrations of FSH and LH were not different between the ++ and I+ genotypes, reflecting similar levels of ovarian follicular activity. However, in adult II animals, the plasma concentrations of FSH and LH were significantly higher (both p < 0.01) than in the ++ and I+ genotypes, reflecting the absence of normal secondary and antral follicles. In summary, these data show that the fecX1 gene affects ovarian development before birth and that the nature of the effect is influenced by whether the female fetus is a homozygous or heterozygous carrier of the X-linked mutation.

Animals↗
PubMed1997

The effectiveness of a preceptorship model in postgraduate education for rural nurses.

This retrospective study was designed to evaluate the effectiveness of a preceptor program in meeting the needs of first-year graduate nurses employed in a large rural hospital. In particular, this project aimed to assess whether the program leads to improvement in the clinical skills of the graduate over the 12-month period of the program; the suitability of the program to meet the graduates' needs; and the perceptions of nursing unit managers, preceptors and enrolled nurses regarding the program. Questionnaires were designed and distributed to the above categories of nurses, as well as graduates. Results indicated that the graduates considered the program to be excellent and that it met their needs to a high degree, while the clinical nurses rated the program between adequate and good. The paper will define the strengths and limitations of the program and the effect on recruitment and retention of nurses in a rural area.

Clinical Competence↗
PubMed1997

Circumventricular organs and fever.

We have examined the roles of three circumventricular organs, the area postrema, the subfornical organ, and the organum vasculosum of the lamina terminalis (OVLT), as possible access points for circulating pyrogens to cause fever. In conscious, unrestrained rats prepared with telemetry devices, intracerebroventricular cannulas, and intravenous catheters, body temperature was monitored after intravenously administered lipopolysaccharide and, on a different occasion, after intracerebroventricular prostaglandin E1. Lipopolysaccharide-induced fevers in sham control lesioned rats were indistinguishable from those observed in animals with lesions of the area postrema, the OVLT, or the tissue immediately adjacent to this structure (peri-OVLT). In contrast, rats with lesions of the subfornical organ displayed reduced fevers. In none of the groups of lesioned animals were prostaglandin E1 fevers reduced. Thus lesions did not interfere with central thermogenic pathways responsive to prostaglandin. Our results indicate that subfornical organ neurons respond to circulating pyrogens and through their efferent projections activate central pathways involved in fever.

Alprostadil↗
PubMed1997

Correlation between ventilation and EEG-defined arousal during sleep onset in young subjects.

In studies of elderly individuals, ventilation and EEG-defined arousal have been shown to vary periodically and synchronously. Such results have been interpreted as indicating the primacy of sleep/wake state in causing ventilatory instability during sleep onset. However, because the elderly individuals studied were periodic breathers, the results do not unequivocally support this conclusion. In this study the relationship between ventilation and EEG-defined arousal was assessed in a group of 21 young, healthy men in whom ventilatory instability during sleep onset was not periodic. Ventilation and EEG (O1-A2) recordings were collected, and the longest uncontaminated periods from early and late in sleep onset were selected for subsequent analysis. The 84 time series (21 subjects, 2 variables, and 2 occasions in sleep onset) were subjected to spectral analysis to identify periodicity, and the relationship between the two variables was determined by cross-correlational methods. The results indicated that the time series were nonperiodic, yet significant correlations were observed between the two variables. The data support the view that during sleep onset ventilatory instability is driven primarily by variations in sleep/wake arousal level.

Adolescent↗
PubMed1997

The effect of transmission bandwidth on diagnostic accuracy in remote fetal ultrasound scanning.

Six subspecialists with considerable experience in fetal ultrasound viewed a selection of pre-recorded ultrasound scans. Scans from 18 patients recorded on VHS video-tape were supplied from five centres in the UK and Ireland, each made on a high-resolution ultrasound machine by an experienced sonologist at a referral centre. Each observer viewed the scans on a large display monitor in an individual viewing booth. The scans were viewed in random order, at randomly selected bandwidths. Observers, who were blinded to both recording and bandwidth, assessed the technical quality on a five-point Likert scale. They also recorded their diagnosis. The six observers each carried out 32 viewing sessions, which gave a total of 192 viewings. There was no significant difference in the perceived technical quality of the scans between the two bandwidths used (P = 0.09). Of the 84 recordings transmitted at 1920 kbit/s, 71 (85%) were diagnosed correctly or 'half correctly' and 13 (15%) were misdiagnosed. Of the 95 recordings transmitted at 384 kbit/s, 66 (69%) were diagnosed correctly or 'half correctly' and 29 (31%) were misdiagnosed. This difference was significant (P = 0.03). The results indicate that although there were no perceived differences in technical quality between recordings transmitted at 384 or 1920 kbit/s, diagnostic accuracy was marginally worse at the lower bandwidth. This suggests that the higher bandwidth conveys more detail and information to the observer, which in turn enables more accurate diagnosis. However, further work is required before a definitive choice can be made about the optimum transmission bandwidth for remote fetal ultrasound studies.

Female↗
PubMed1997

Expression of the ovine stem cell factor gene during folliculogenesis in late fetal and adult ovaries.

Two ovine stem cell factor (oSCF) cDNAs (822 bp and 738 bp) were generated from ovarian follicle mRNA by RT-PCR. Nucleotide sequencing revealed that the oSCF 822 bp cDNA encodes a precursor protein of 274 amino acids. An amino acid change 109E to 109Q was the only sequence difference from that previously described for this species. The smaller (738 bp) oSCF cDNA was shown by nucleotide sequencing to be an mRNA splice variant, equivalent to that found in other mammals, in which an exon (84 bp) encoding a potential proteolytic cleavage site is removed. Northern analysis revealed a single transcript of approximately 6.5 kb in follicles, corpora lutea and stroma of mid-luteal sheep ovaries. In situ hybridization was used to detect oSCF mRNA within ovaries of fetal sheep on days 90, 100, 120 and 135 of gestation (term = 147) and of adult sheep within the breeding season. In fetal and adult ovaries, oSCF mRNA was detected in the granulosa cells of follicles at all stages of follicle growth (primordial through to antral). The SCF gene was also expressed in granulosa cells of atretic follicles but appeared to be down-regulated in the cumulus cells surrounding the oocyte at more advanced stages of atresia. In fetal ovaries at day 90 of gestation (90DG), oSCF was expressed in the subepithelial mesenchymal cells of the ovarian cortex. By 100DG the gene expression in the subepithelial cells became restricted to a narrow region below the epithelium, and areas of expression were observed in groups of cells around isolated oocytes, primordial and primary follicles. oSCF gene expression also occurred in the surface epithelial cells of 90DG ovaries, the expression was absent from these cells by 135DG and in adult ovaries. Localization of oSCF mRNA was observed in the ovarian rete and endothelial cells of blood vessels of fetal ovaries. These results suggest that oSCF may have an important and continuous role in the development and/or maintenance of germ cells during follicle growth and atresia in sheep.

Animals↗
PubMed1997

Physical performance of elite New Zealand Olympic class sailors.

OBJECTIVE: The purpose of this study was to compare the physical performance of elite New Zealand and other nations olympic class sailors and to undertake an initial examination of the relation between physical and sailing performance. EXPERIMENTAL DESIGN: A comparative study. SETTING: Healthy elite national level olympic class sailors were examined. PARTICIPANTS: Thirty-one elite New Zealand Olympic sailing squad team members and 108 Olympic team sailors from ten other nations. INTERVENTIONS: The data for the two groups of subjects was compared using unpaired "t"-tests. A qualitative analysis was used to examine the relation between physical and sailing performance. MEASURES: Measurements included age, body mass, muscular strength endurance (as assessed by the maximum number of push-ups, pull-ups and sit-ups that could be performed) and serobic power (as assessed by the time taken to cover 2500 m and the distance completed in 12 minutes in a maximal effort rowing ergometer test). Sailing performance was assessed by national coach ranking of each New Zealand sailor. RESULTS: On average the New Zealanders were younger and lighter than the sailors from the other nations. They tended to have greater shoulder/arm strength endurance as reflected in their performance for push-ups and pull-ups, but a lesser ability in their sit-up performance. They also tended to be aerobically fitter. There were clear and logical differences between body mass and both class of vessel and the position of the sailor i.c. crew or helmsman. Lighter sailors sailed lighter craft whilst heavier sailors sailed the heavier craft. Crew members were generally heavier than helmsmen. Age appeared to be related to sailing performance. CONCLUSIONS: Elite New Zealand Olympic class sailors tend to be younger, lighter, stronger and aerobically fitter than elite sailors from other nations. Age appeared to be related to on-water sailing performance.

Adolescent↗
PubMed1997

Comparison of human apoA-I expression in mouse models of atherosclerosis after gene transfer using a second generation adenovirus.

Gene transfer and expression of apolipoprotein A-I (apoA-I), the major protein component of high density lipoproteins (HDL), is a potentially attractive method for investigating the effects of apoA-I on atherosclerosis. We constructed a second generation recombinant adenovirus encoding the human apoA-I cDNA. This adenoviral vector or a control vector was injected intravenously into apoE-deficient mice fed a chow diet and low density lipoprotein (LDL) receptor (LDLR)-deficient mice fed Western diet, as well as control wild-type C57BL/6 mice. The mean peak plasma human apoA-I concentrations were 235, 324, and 276 mg/dL in apoE-deficient, LDLR-deficient, and wild-type mice, respectively. Human apoA-I concentrations decreased rapidly in apoE-deficient mice and were barely detectable 6 weeks after injection. In contrast, substantially higher levels of human apoA-I were sustained in LDLR-deficient mice. In wild-type mice, human apoA-I levels decreased more rapidly than in LDLR-deficient mice, but could still be detected in plasma for up to 8 months after virus injection. In apoE-deficient mice a substantial fraction of human apoA-I was found associated with triglyceride (TG)-rich lipoproteins; in contrast, in LDLR-deficient and wild-type mice the majority of human apoA-I was found in the HDL fraction. Finally, expression of human apoA-I caused a transient but significant increase in triglyceride levels in all three mouse models. In summary: 1) a second generation recombinant adenovirus resulted in high-level expression of human apoA-I in mice; 2) significantly higher levels of human apoA-I persisted for a longer time in LDLR-deficient mice compared with apoE-deficient mice; and 3) substantial human apoA-I was found associated with TG-rich lipoproteins in apoE-deficient but not LDLR-deficient mice.

Adenoviridae↗
PubMed1997

Knowledge and reported use of sport science by elite New Zealand Olympic class sailors.

OBJECTIVE: This study enquired about the knowledge and reported use of sport science in elite Olympic class sailors. EXPERIMENTAL DESIGN: The sailors responded to a simple questionnaire. SETTING: The questionnaire was administered as part of an introductory seminar on sport science during a training camp. PARTICIPANTS: The participants were 28 (22 male, 6 female) elite New Zealand Olympic class sailors. INTERVENTIONS: None. MEASURES: The questionnaire asked whether or not they used a training race diary, enquired about their current and past injuries and their knowledge and use of sport science in the areas of nutrition, psychology and physical training. RESULTS: Only ten (36%) of the sailors kept a training/race diary. Whilst only four (14%) had a current injury, sixteen (57%) reported an injury in the previous three years. The injuries were in the lower back (45%), knee (22%), shoulder (18%), and arm (15%). Although nineteen (68%) of the sailors had experienced dehydration during racing, the average volume of fluid reported to be taken on a four hour sail was only 0.9 litre, of which only an average of 0.7 litres (77%) was reported to be drunk. All the sailors reported being sometimes (46%) to very often (3%) anxious before races and sometimes (43%) to always (7%) being frustrated with their own mistakes. Only one sailor reported never having negative thoughts whilst fifteen (53%) reported having them sometimes, and seven (25%) often or very often. Twenty-four (86%) of the sailors reported that they sometimes had a loss of concentration near the end of the race. Whilst eighteen (64%) reported practising relaxation and seventeen (61%) reported practising visualisation as a mental skill, only five (18%) practised progressive mental relaxation, two (7%) practised meditation and none practised yoga. Seventeen (61%) undertook strength/circuit training, ten (36%) flexibility and twenty-one (75%) off water aerobic training. Twenty-four (86%) reported undertaking on-water aerobic training. CONCLUSIONS: The results indicate that there is considerable scope for improvement in the knowledge and use of sports science amongst elite New Zealand Olympic class sailors.

Adolescent↗
PubMed1997

Simultaneous bilateral versus unilateral total knee arthroplasty. Outcomes analysis.

One hundred consecutive, primary simultaneous bilateral total knee arthroplasties were prospectively compared with 100 consecutive, primary unilateral total knee arthroplasties in reference to relative risk, complications, cost, and need for rehabilitation. All procedures were performed using identical preoperative, intraoperative, and postoperative protocols. Postoperative confusion was approximately four times greater in the simultaneous bilateral total knee arthroplasties group (29% versus 7%), which was thought to represent an increased incidence of fat embolism. Cardiopulmonary complications were approximately three times greater after simultaneous bilateral total knee arthroplasties (14% versus 5%), and most commonly involved arrhythmias. The increased stress on the cardiopulmonary system with simultaneous bilateral total knee arthroplasties may make this procedure contraindicated in certain patients with preexisting disease. There was an approximately 17 times greater need for banked blood in the simultaneous bilateral total knee arthroplasties group (17% versus 1%), which is alarming given the persistent concerns of transfusion related disease transmission. Although the length of hospitalization was similar (6.4 days simultaneous bilateral total knee arthroplasties versus 6 days unilateral total knee arthroplasty), 89% of the patients in the simultaneous bilateral total knee arthroplasties group required a rehabilitation stay versus 45% of the patients in the unilateral total knee arthroplasty group. Total hospital charges averaged $53,168 for simultaneous bilateral total knee arthroplasties versus $32,598 for unilateral total knee arthroplasty. Total rehabilitation charges were similar. The relative cost savings implicit by doing simultaneous bilateral total knee arthroplasties seem to be at least partially offset by the approximately two times greater need for rehabilitation in this group. The true safety, efficacy, relative risk, and total cost analysis of simultaneous bilateral total knee arthroplasties demands further critical evaluation.

Adult↗
PubMed1996

Development and validation of an indirect enzyme immunoassay for detection of antibody to Anaplasma marginale in bovine sera.

An indirect enzyme immunoassay (IELISA) for detection of bovine antibody activity to Anaplasma marginale was developed. This assay used a crude antigen prepared from erythrocytes of infected calves, immobilized in a polystyrene matrix and a mouse monoclonal antibody to bovine IgG1, conjugated with horseradish peroxidase. Negative sera (n = 1842) were tested and the diagnostic specificity was 98.4 +/- 0.6% before retesting 29 positive samples. After retesting, eight samples remained positive and the specificity was calculated to be 99.6 +/- 0.3%. The diagnostic sensitivity, using 831 serum samples collected from naturally or experimentally infected cattle in Argentina, 370 from Mexico and 525 sera from experimentally vaccinated or infected cattle from Texas, was 87.3 +/- 1.6%.

Agglutination Tests↗
PubMed1996

A homogeneous fluorescence polarization assay for detection of antibody to Brucella abortus.

A homogeneous fluorescence polarization (FP) assay (FPA) was developed for detection of antibody in bovine sera to Brucella abortus. The assay used O-polysaccharide prepared from B. abortus lipopolysaccharide in the molecular weight range of 20-30 kDa which was conjugated with fluorescein isothiocyanate and used as a tracer. Fluorescence polarization was measured with a FPM-1 fluorescence polarization analyzer. Sample (20 microliters) was added to 2.0 ml of diluent buffer at ambient temperature. A serum blank reading was taken and tracer (10 microliters) to yield approx. 1.5 nM fluorescein equivalents was added. The FP of the tracer was determined after a period of greater than 2 min. A positive reaction was indicated by a significant elevation of the FP reading over the negative control. In a blind study, 9480 bovine sera were tested in addition to sets of four controls which were included with each lot of 100 samples tested. The controls were a strong positive, a weak positive, a negative and a serum derived from a B. abortus strain 19 vaccinated cow. Test sera included 8669 sera from Canadian cattle which were negative by routine serological tests, 561 sera from cows from which B. abortus had been isolated either from tissues or milk and 250 sera from cattle previously vaccinated with B. abortus strain 19 at various times. One lot of O-polysaccharide tracer was used for all tests. The initial cut-off for negative samples in the fluorescence polarization assay was set at 107.2 mP. This resulted in a sensitivity estimate of 98.1 +/- 1.1% and the specificity was 99.8 +/- 0.09%. After decoding the samples and retesting false positive and negative reactions, the sensitivity estimate was 98.5 +/- 1.0% and the specificity was 100%. It became evident that the initial cut-off value was set too high and, using ROC analysis, a cut-off of 90 mP increased the sensitivity to 99.02% while the specificity decreased to 99.96%. Of the 250 sera from vaccinated cattle, 248 were negative giving a point specificity value of 99.2%.

Animals↗
PubMed1996

Cyclin D1 and prognosis in human breast cancer.

We have used immunohistochemical staining to assess the expression of cyclin D1 in formalin-fixed sections of 345 breast carcinomas, dating back 20 years. Clinical follow-up data were available on all patients. Approximately 50% of the tumours showed excessive nuclear staining for cyclin D1 as compared with normal epithelium. Some tumours showed strong cytoplasmic staining in the absence of nuclear staining, and around 25% of the tumours were judged to be negative for nuclear cyclin D1. Contrary to expectations, moderate/strong staining for cyclin D1 was associated with improved relapse-free and overall survival relative to patients whose tumours stained weakly or negatively. Conversely, tumours that were considered negative for cyclin D1 staining had an adverse prognosis, and the poor outcome was further accentuated if the tumours were also oestrogen receptor-negative. A possible explanation for our findings is that tumours in which cyclin D1 levels are abnormally low may have sustained mutations in other genes, such as RBI and that it is this abnormality that has the more significant impact on survival from breast cancer.

Adult↗