PubMed Health⌕ Search

Biomedical subjects

P Ballard

Publications and source records attributed to P Ballard.

At least 19 recordsLinked to original sources
PubMed2000

Prediction of in vivo tissue distribution from in vitro data 1. Experiments with markers of aqueous spaces.

PURPOSE: The aim of this study was to evaluate the ability of an in vitro method of tissue distribution to accurately predict total water and extracellular aqueous spaces using marker compounds urea and inulin. METHODS: Slices (50-200 mg) of all the major tissues in the rat were incubated with Hanks/HEPES pH7.4 buffer containing 14C-urea and 3H-inulin for 2 h at 37 degrees C. Tissue weight was noted before and after incubation and the tissue-to-buffer ratios determined. RESULTS: 14C-Urea Kp estimates were generally greater than total tissue water due to tissue swelling, which varied widely among the tissues, up to 41% in muscle. In most cases, Kp values were much closer to in vivo values after correcting for the 14C-urea in the imbibed media (Kpcorr). The method was able to distinguish between 14C-urea and 3H-inulin Kp values and indicated that inulin occupied a smaller space than urea, which for the majority of tissues corresponded to the extracellular space. CONCLUSIONS: The Kp(corr) values for 14C-urea and Kp for 3H-inulin were consistent with total tissue water and extracellular space for the majority of tissues studied, indicating their suitability as marker compounds for checking the viability of this in vitro method for estimating tissue distribution.

Animals↗
PubMed2000

Errors in the measurement of endometrial depth using transvaginal sonography in postmenopausal women on tamoxifen: random error is reduced using saline instillation sonography.

OBJECTIVE: The endometrium in women on tamoxifen is often made irregular by small cysts. The aim of this study was to assess the accuracy and precision of the measurement of endometrial depth by transvaginal sonography. METHODS: The endometrial depth from endometrial biopsies obtained with the resectoscope in 15 women receiving tamoxifen was compared to the endometrial depth measured by TVS. The inter-observer variability was measured in 58 women. RESULTS: In those biopsies of sufficient quality to allow a measurement, the corresponding depth measurement obtained by ultrasound was up to 3 mm greater than the histological measurement. The interobserver variability for the measurement of endometrial depth using TVS was assessed in 58 postmenopausal women on tamoxifen. The interobserver variability deteriorated as the mean endometrial depth increased, probably because the increase in depth resulted from greater morphological changes within the endometrium such as cyst formation which resulted in an irregular endometrial/myometrial boundary. This may, however, be improved by performing saline instillation sonography. In a prospective study of 10 postmenopausal women, the interobserver variability was significantly greater during tamoxifen treatment compared to pretreatment. CONCLUSIONS: On the basis of the above, if uterine surveillance using TVS were to be offered to postmenopausal women on tamoxifen, then the procedure should be augmented by saline instillation sonography if the endometrial depth is > 4 mm, as this will improve the measurement precision and also identify intrauterine pathology.

Antineoplastic Agents, Hormonal↗
PubMed1999

Bone remodeling and structure in postmenopausal women treated with long-term, high-dose estrogen therapy.

Conventional hormone replacement therapy preserves bone mass predominantly by reducing bone turnover but does not exert significant anabolic skeletal effects. In contrast, high doses of estrogen have been shown to increase bone formation in animals and we have recently reported high bone mineral density values in women treated long-term with estradiol implant therapy. The aim of this study was to investigate the mechanisms by which high doses of estrogen may increase bone mass in postmenopausal women. Iliac crest biopsies were obtained from 12 women who had received long-term treatment with estradiol implants (at least 14 years), on demand, following hysterectomy and bilateral salpingo-oophorectomy. Indices of bone turnover, remodeling balance and cancellous bone structure were assessed by image analysis and compared with those of premenopausal women. Mean wall width was significantly higher in women treated with estradiol therapy than in premenopausal women (44. 8 +/- 4.8 vs 38.8 +/- 2.8 mm; mean +/- SD; p = 0.001) and eroded cavity area was significantly lower in the implant-treated women (3612 +/- 956 vs 5418 +/- 1404 mm(2); p = 0.001). Bone formation rate at tissue level and activation frequency were lower in the women treated with implants, although the differences were not statistically significant. Indices of cancellous bone structure were generally similar between the two groups. These results provide the first direct evidence that high-dose estrogen therapy produces anabolic skeletal effects in postmenopausal women and indicate that these are achieved by stimulation of osteoblastic activity.

Aged↗
PubMed1999

Development of an assay for the extraction and quantification of nine 5-n-alkyl-5-ethyl barbituric acids in various rat tissues.

Methods were developed to quantify a series of nine homologous 5-n-alkyl-5-ethyl barbituric acids in 15 rat tissues. Tissue homogenates were spiked with one of four multicomponent mixtures (methyl to n-propyl, n-propyl to n-pentyl, n-pentyl to n-heptyl and n-pentyl to n-nonyl). Liquid-liquid extraction was used to extract the homologues from the rat tissues. Reverse phase HPLC with UV detection at 214 nm was used to separate and quantify the individual barbiturates. The limit of detection for each respective homologue was 1 microg x g(-1) except skin and bone (2 microg x g(-1)). The methodology developed reduced a potential 135 individual assays to a more manageable 16.

Animals↗
PubMed1999

MRI in vitamin B12 deficiency myelopathy.

BACKGROUND: Little is known about vitamin B12 deficiency myelopathy's magnetic resonance imaging (MRI) manifestations and their relationship to the onset, evolution, and resolution of neurologic signs and symptoms. METHODS: We present a case and review eleven additional reported cases of subacute combined degeneration of the spinal cord detected by MRI. RESULTS: Our patient had increased T2-weighted signal and gadolinium contrast enhancement of the posterior columns in the cervical and thoracic regions and enhancement of the lateral columns in the high cervical region. This is a case with imaging evidence for lateral column lesions. Two prior reports have shown posterior column enhancement. T1-weighted images may show decreased signal in the posterior columns and sometimes demonstrate reversible spinal cord swelling. MRI abnormalities typically improve after vitamin replacement therapy. However, clinical signs may persist despite resolution of imaging abnormalities, and these abnormalities do not always resolve completely. In addition, symptoms may precede the imaging abnormality. CONCLUSIONS: Vitamin B12 deficiency may produce an increased T2-weighted signal, decreased T1-weighted signal, and contrast enhancement of the posterior and lateral columns of the spinal cord, mainly of the cervical and upper thoracic segments. Because the symptoms may precede any imaging abnormality, it is clear that spinal cord MRI may not be a highly sensitive, early test for subacute combined degeneration.

Adult↗
PubMed1999

Our specialty is quality cancer care.

"The life cycle of the oncology nurse is the career trajectory of the individual nurse. For some nurses, it expands from the point prior to entry into the profession to the stage of senior leadership" (McDonnell & Ferrell, 1992). In conjunction with Oncology Nursing Month (April 28-May 31), five nurses at different points in their careers--from new graduate to seasoned practitioner--share their insights into oncology nursing and the trajectory within their individual careers. The ONS Life Cycle Task Force identified several essential concepts that are major influences throughout the life cycle of the oncology nurse, including critical incidents, influential people, balancing roles, volunteerism, nature of the work, patient and family outcomes, essences of oncology nursing, diversity, specialization, and environment culture. These influences are apparent in the stories of each of the nurses featured in this article.

Career Choice↗
PubMed1998

An approach to the evaluation and comparison of reversed-phase high-performance liquid chromatography stationary phases.

An approach to the evaluation and comparison of reversed-phase high-performance liquid chromatography stationary phases with particular emphasis on data analysis and presentation is described. Assessment is based on the peak efficiency, asymmetry (USP tailing factor) and relative retention properties shown by 24 basic compounds having a wide range of structural and physico-chemical properties. A novel approach to data normalisation and presentation is described. This overcomes the problems associated with the quality of the column packing process, as well as differences in stationary phase selectivity which in conjunction with extra column band broadening effects can make comparisons meaningless.

Buffers↗
PubMed1998

Enhanced patient care is the ultimate nursing research goal.

Nurses everywhere face increasingly complex healthcare-delivery challenges. Here, Claire Meci, Kathleen Pelc, Jennifer Aikin, Lois Van Cleve, and Cheryl Mummy discuss the varied roles of the researcher and how nursing research is challenging, changing, and enhancing current nursing practice as it moves toward the ultimate goal of research-based practice.

Humans↗
PubMed1997

A randomised trial evaluating pain and bleeding after a first trimester miscarriage treated surgically or medically.

Miscarriage treated surgically and medically were compared in a randomised controlled trial evaluating pain and bleeding. Surgery is associated with less pain (P < 0.03) and vaginal bleeding (duration and severity, P = 0.001) than medical treatment, fewer daily hospital attendances (2.5 compared with three, P = 0.04) but a greater drop in haemoglobin concentration (difference, 1 g/dl; CI95% = 0.3-1.6).

Abortion, Spontaneous↗
PubMed1997

The effect of long-term oestradiol implantation on bone mineral density in postmenopausal women who have undergone hysterectomy and bilateral oophorectomy.

Twelve women who had received oestradiol implantation on demand for at least 15 years following hysterectomy with bilateral oophorectomy, underwent bone densitometry of hip and spine. Bone mass of hip and spine was significantly elevated above that of both the age matched mean to a degree hitherto undocumented. This suggests that oestrogen in high doses or over a long period may produce a true anabolic effect on bone mass.

Absorptiometry, Photon↗
PubMed1996

The development and performance of a radioimmunoassay for the analysis of ZM 213,689, the major metabolite of meropenem--a carbapenem antibiotic--in plasma and urine.

The development of a radioimmunoassay for the analysis of ZM 213,689, the major metabolite of meropenem found in the plasma and urine of rat, dog and humans, is described. The assay is rapid in order to minimise the effect of degradation of meropenem to ZM 213,689 in biological samples and has a working range of 0.08-3.5 mg l-1 (RSD < or = 15%). The antibody was specific for ZM 213,689 with cross-reactivity to meropenem of only 0.4%. The synthesis of the immunogen and radiotracer involved a novel approach due to the multifunctional nature of ZM 213,689.

Animals↗
PubMed1994

The use of competitive displacement agents to resolve albumin binding problems observed during the development of a radioimmunoassay for ICI 215001.

A radioimmunoassay has been developed for the analysis of ICI 215001, a carboxylic acid metabolite of ICI D7114. The level of binding and sensitivity of the assay were good in the absence of plasma. However, the addition of plasma to the incubation medium reduced the antibody binding of radiolabelled tracer (I) from 41 to 9%. This was attributed to the high (> 99%) plasma albumin binding of ICI 215001. A series of compounds (DL-tryptophan, octanoic acid, bilirubin, ponalrestat, warfarin, phenylbutazone and salicylic acid) which all bind to plasma albumin, were examined for their effect on the tracer-antibody interaction. Warfarin and phenylbutazone were the only compounds to specifically displace the iodinated tracer from albumin; warfarin was the only compound to restore antibody binding to control levels. The warfarin concentration and the pH of the incubation medium also had a substantial effect on the magnitude of the displacement. The optimized method for the analysis of ICI 215001 in human plasma (20 microliters) used phosphate buffer (pH 6.0, 0.1 M) containing warfarin (50 micrograms ml-1), which gave an assay with the desired specificity, precision and sensitivity.

Adrenergic beta-Agonists↗
PubMed1990

Chromatographic retention relationships between aliphatic tertiary amines and their putative N-oxide metabolites--preliminary results.

The chromatography of a series of tertiary amines and the corresponding N-oxides have been studied and the Functional Group Contribution Approach used to describe retention correlations between them. Good correlations are observed between the behaviour of compounds on HPLC and with the exception of some alicyclic nitrogen compounds also on thin layer chromatography. The models produced are used to predict k' and Rf values for ranitidine N-oxide and tamoxifen N-oxide based upon those for the parent molecule. The deviation between actual and predicted values was larger than expected, presumably due to the structural or physico-chemical differences of ranitidine and tamoxifen compared to the model compounds.

Amines↗