Biomedical subjects

R J Moore

Publications and source records attributed to R J Moore.

At least 37 records · Page 2Linked to original sources

PubMed2000

Echoplanar imaging in GI clinical practice: assessment of gastric emptying and antral motility in four patients.

Gastric emptying, frequency of antral contractions, and speed of antral contraction propagation were assessed in four patients using echoplanar imaging techniques. The results obtained and their impact on the diagnosis and management of the patients are presented and discussed. This shows that echoplanar evaluation of gastric function is noninvasive, well-tolerated by patients, detects clinically relevant abnormalities, and has the potential of becoming a valuable examination in the clinical gastrointestinal practice.

Adult↗

PubMed2000

Early histologic changes in lower lumbar discs and facet joints and their correlation.

Biomechanical and histologic studies have highlighted the close functional relationship between lumbar discs and their associated facet joints, and it is conceivable that their degenerative changes are interdependent. However, separation of cause from effect remains controversial. Hitherto, no study in humans has correlated the changes histologically. The present study assessed histologic changes in lower lumbar discs and their associated facet joints in patients under the age of 40 years using classification systems developed for this investigation. A specific objective was to correlate changes in discs and facet joints. Data from 15 lower lumbar spine specimens were obtained. Three parasagittal sections per disc and one section per facet joint were graded histologically. The results were correlated with age, within the functional spinal unit (FSU), and with the adjacent level. Histologic changes were found in discs and facet joints from all FSUs. There was no correlation between the age of the subject and the degree of degeneration of the disc or facet joints at either level. The extent of disc degeneration at L4/5 correlated significantly with changes at L5/S1 (P < 0.01). There was no correlation between changes in discs and the associated facet joints at either level. The results of the study showed that microscopic changes are seen in the disc and facet joints from an early age and can be quite marked in some individuals before the age of 40 years. A correlation of degenerative changes within the FSU could not be established.

Adolescent↗

PubMed2000

The vertebral end-plate: what do we know?

The vertebral end-plate is critical for maintaining the health of the intervertebral disc. This paper reviews the literature that relates to end-plate structure and development and describes how disc integrity is affected by changes associated with pathology and aging. A range of studies, including biomechanical, biochemical, surgical and histological is discussed to illustrate the important role of the end-plate in spinal function.

Animals↗

PubMed2000

In utero perfusing fraction maps in normal and growth restricted pregnancy measured using IVIM echo-planar MRI.

The aim of this study was to measure and portray blood movement in the placenta in vivo in normal and growth restricted pregnancies, using Intra Voxel Incoherent Motion (IVIM) magnetic resonance imaging. Thirteen patients with apparently normal healthy pregnancies were scanned at 31+/-7 (mean+/-s.d.) weeks gestation and seven patients with intrauterine growth restriction (IUGR) were scanned at 31+/-4 weeks. A region of interest (ROI) was defined encompassing the placenta between the decidual and chorionic plates. The volume of moving blood within each imaging voxel of the ROI was then calculated as a percentage of the total voxel volume (f per cent). This information was colour coded to produce maps of moving blood volume. The placenta was segmented length ways into two zones of approximately equal area, termed inner and outer, the latter being adjacent to the uterine wall. f was fitted for the average in the outer zone (f(out)) and inner zone (f(in)). The parameter (f(out)-f(in)) was then calculated for each subject. This was positive in 12/13 of the normal cases and zero for one case (+10 per cent+10, mean+/-s.d.). For pregnancy affected by IUGR this value was negative in all cases (-4 per cent+/-3). Perfusion fraction mapping identified differences in function within the normal placenta in vivo, and between the placentae of normal and IUGR pregnancies. The technique has potential applications in managing, and investigating the aetiology of, pregnancy compromise.

Blood Volume↗

PubMed2000

Effect of fetal magnetic resonance imaging on fetal heart rate patterns.

OBJECTIVE: Our aim was to record the fetal heart rate before and during magnetic resonance imaging to observe the effects of the magnetic resonance imaging process on fetal heart rate parameters during imaging. STUDY DESIGN: Fetal heart rate recordings were obtained in 10 pregnant volunteers at the time of magnetic resonance imaging. All the pregnant women were at term (37-41 weeks) with singleton fetuses in the cephalic presentation. The scanning was performed on a 0.5-T purpose-built superconductive magnet by use of echo-planar imaging. The fetal heart recordings were obtained with a modified Sonicaid Meridian 800 (Oxford) Doppler ultrasound monitor. Recordings of the fetal heart were made for a period of at least 15 minutes outside the magnet and then for at least 15 minutes inside the magnet. RESULTS: There were no significant changes in any fetal heart rate parameters before and during the magnetic resonance imaging, as determined by the Wilcoxon matched-pairs signed-ranks test (P >.3). CONCLUSION: This is the first report of fetal heart rate recording during magnetic resonance imaging of the fetus. Magnetic resonance imaging does not produce demonstrable effects on fetal heart rate patterns.

Cardiotocography↗

PubMed2000

Gastric response to increased meal viscosity assessed by echo-planar magnetic resonance imaging in humans.

Normal meals are highly viscous, and viscosity is a key factor in influencing gastric emptying of food. However, the process of meal dilution and mixing is difficult to assess with the use of conventional methods. The aim of this study was to validate an in vivo, novel, noninvasive, echo-planar magnetic resonance imaging (EPI) technique, capable of monitoring the viscosity of a model meal, and to use this to investigate the effects of viscosity on gastric emptying, meal dilution and satiety. Healthy volunteers (n = 8) ingested 500 mL of locust bean gum (0.25, 0.5, 1.0 or 1.5 g/100 g), nonnutrient, liquid meals of varying viscosities, and labeled with a nonabsorbable marker, phenol red. Meal viscosity was calibrated against the water proton transverse relaxation rate (T(2)(-1)) in vitro before ingestion, thus viscosity was measured in vivo via EPI measurements of T(2)(-1). Viscosity and dilution were also measured directly using nasogastric aspirates. Gastric volumes as measured by EPI, fullness, appetite and hunger were also assessed serially. Before ingestion, the log of initial meal viscosity was linearly related to T(2)(-1) (n = 8, r(2) = 0.95). Similarly, T(2)(-1) measured in vivo was also linearly related to the viscosity of the aspirates (r(2) = 0.88). All meals underwent rapid dilution, leading to a reduction in viscosity, which was greatest for the most viscous meal (P < 0.01). Surprisingly, despite the fact that the initial meal viscosity varied 1000-fold, there was only a small delay in gastric emptying (P for trend < 0.05). The area under the curve for satiety increased with initial meal viscosity, whereas that for hunger decreased (P < 0.05). In conclusion, the viscosity of a meal in vivo can be measured noninvasively using EPI. The stomach responds to meal ingestion by rapid intragastric dilution, causing a reduction of meal viscosity, and gastric emptying is minimally delayed. However, increased viscosity is associated with more prolonged satiety.

Adult↗

PubMed2000

Endocrine markers of semistarvation in healthy lean men in a multistressor environment.

We tested the hypothesis that key endocrine responses to semistarvation would be attenuated by changing only the food intake in a multistressor environment that also included sustained workload, inadequate sleep, and thermal strain. Serum hormones were compared within and between two groups of healthy young male volunteers participating in the 8-wk US Army Ranger course, with four repeated cycles of restricted energy intakes and refeeding: group 1 (n = 49) and group 2 (n = 48); energy deficits averaged 1,200 and 1,000 kcal/day, respectively. After 8 wk, most of group 1 achieved a minimum body fat, serum 3,5,3'-triiodothyronine (T(3)) was below normal (78 +/- 20 ng/dl), testosterone (T) approached castrate levels (4.5 +/- 3.9 nmol/l), insulin-like growth factor I (IGF-I) declined by one-half (75 +/- 25 microg/l), and cholesterol rose from 158 +/- 31 to 217 +/- 39 mg/dl. Bioavailable T(3) and T were further reduced by increases in their specific binding proteins in response to declining insulin. Refeeding, even with continuation of the other stressors, produced prompt recovery of T(3), T, and IGF-I. Higher energy intakes in group 2 attenuated the subclinical hypothyroidism and hypercholesterolemia, whereas consistent luteinizing hormone suppression indicated centrally mediated threshold effects on gonadal hormone suppression. We conclude that low T, T(3), and IGF-I remained reliable markers of acute energy deficits in the presence of other stressors; elevated cholesterol and cortisol provided information about chronic status, corresponding to diminishing body fat stores.

Adult↗

PubMed2000

The effect of case management on the costs of health care for enrollees in Medicare Plus Choice plans: a randomized trial.

OBJECTIVE: To measure the effects of case management on an older population's costs of health care. DESIGN: A 1-year randomized controlled trial. SETTING: Multiple sites of care in San Francisco, California. PARTICIPANTS: Patients aged 65 or older of primary care physicians in a large provider organization bearing financial risk for their care (n = 6409). INTERVENTION: Screening for high risk and provision of social work-based case management. OUTCOME MEASURES: Volume and cost of hospital, physician, case management, and other health-related services. RESULTS: The experimental group used more case management services than the control group (0.09 vs. 0.02 months per person, P<.001). The experimental group's average total payments for health care were slightly lower ($3148 vs $3277, P = .40). CONCLUSIONS: This study provides no statistically significant evidence that social work-oriented case management reduces the use or the cost of health care for high-risk older people. Other potentially favorable effects of this type of case management need to be evaluated, as do the effects of other types of case management.

Aged↗

PubMed1999

Foreign gene expression in Corynebacterium pseudotuberculosis: development of a live vaccine vector.

A defined phospholipase D mutant of Corynebacterium pseudotuberculosis, designated Toxminus, was used as a live vector to express and deliver a range of candidate vaccine antigens to sheep. Expression levels of the foreign genes in Toxminus were evaluated when directed from a number of different promoters, both constitutively expressed and inducible, as fusions with expressed genes including a signal sequence, and from chromosomal and episomal loci. In general expression levels were low and it appeared that some of the recombinant proteins were tolerated by C. pseudotuberculosis Toxminus better than others. Gene expression was however sufficiently high for three of the genes to elicit antibody responses specific to the recombinant protein following a single dose of the live Toxminus vector vaccine. This work suggests that C. pseudotuberculosis Toxminus has potential for development as a live veterinary vaccine vector.

Animals↗

PubMed1999

Osteoarthrosis of the facet joints resulting from anular rim lesions in sheep lumbar discs.

STUDY DESIGN: Facet joints from sheep lumbar spines were examined for histologic evidence of osteoarthrosis after anular incision. OBJECTIVES: To describe the sequence of changes in facet joints in an animal model of disc degeneration. SUMMARY OF BACKGROUND DATA: There are many studies with results showing a link between facet joint osteoarthrosis and disc degeneration, but the development of osteoarthrosis in facet joints has not been observed in a controlled study of disc degeneration. METHODS: Histologic features of facet joint degeneration were compared with established descriptions of human osteoarthrosis, and the sequence of changes was documented in a controlled prospective study of disc degeneration. RESULTS: Osteoarthrosis in sheep lumbar facet joints is similar to that described in human joints and develops in response to anular injury. Discs degenerate relatively soon after anular incision, but there is a long delay in the appearance of significant changes to the facet joints at the level of anular incision and adjacent levels. CONCLUSIONS: The results shows that facet joints in sheep undergo osteoarthrotic changes in response to disc degeneration and confirm the sheep as a suitable model for the study of degenerative spinal disorders.

Animals↗

PubMed1999

Epithelioid variant of malignant peripheral nerve sheath tumor (malignant schwannoma) of the urinary bladder.

Sarcoma represents less than 2% of all neoplasms diagnosed or recognized in effusions. Epithelioid peripheral nerve sheath tumor is a rare tumor that is difficult to differentiate from other epithelioid tumors without the use of ancillary studies. A 39-year-old paraplegic man presented with hematuria and a bladder mass that extended to involve the pelvic peritoneum. Light microscopy using hematoxylin-eosin, Papanicolaou, and immunohistochemical stains as well as transmission electron microscopy showed features of epithelioid malignant peripheral nerve sheath tumor with rhabdoid features and an accompanying eosinophilic infiltrate. Cytologic smears confirmed the similarities between the primary tumor in the bladder and the cells in the pelvic fluid and excluded the possibility of reactive changes related to postsurgical radiation. Ancillary studies were critical in narrowing the differential diagnoses and reaching the final conclusion.

Abscess↗

PubMed1999

Comparison of three methods for estimation of bone resorption following ovariectomy in the distal femur and the proximal tibia of the rat.

The study of estrogen-deficient bone loss requires accurate assessment of bone resorption; however, there has been considerable variance in the values reported for this variable. We compared three techniques for estimating bone resorption in the adult rat at four anatomical sites, the metaphysis and epiphysis of the distal femur and the proximal tibia. The techniques include an osteoclast-morphology-based method (VK-Oc), a bone-surface-based method (Pit-Oc), and an enzymatic method (AP-Oc). Thirty 6-month-old rats were either ovariectomized (ovx) or sham operated (sham) and killed at 0, 9, or 18 days postoperation. Each method was analyzed for variance in the ovary-intact groups and for the ability to detect the increase in osteoclast surface known to occur following ovariectomy. A 50-fold variation for the estimation of extent of osteoclast surface was entirely accounted for by these three methods for osteoclast estimation. The VK-Oc method was the most consistent for discriminating levels of osteoclast surface between ovary-intact and ovariectomized rats, detecting an increase at three of the four sites. There was no difference between the methods in their ability to produce consistent values for ovary-intact groups. The Pit-Oc method produced the largest numerical difference between the two operation groups with a 2.5-3-fold increase compared with 1.25-1.5-fold for the other methods (p < 0.001). However, the greater variance associated with this method limited the ability to detect the increase in osteoclast surface following ovariectomy. The AP-Oc method lacked the sensitivity of the other two methods. The oophorectomy-induced increase of osteoclast surface in the metaphysis of distal femur was larger and more consistently demonstrated than increases at the other sites.

Animals↗

PubMed1999

Mice deficient in tumor necrosis factor-alpha are resistant to skin carcinogenesis.

Given the associations between chronic inflammation and epithelial cancer, we studied susceptibility to skin carcinogenesis in mice deficient for the pro-inflammatory cytokine TNF-alpha (refs. 5,6). TNF-alpha(-/-) mice were resistant to development of benign and malignant skin tumors, whether induced by initiation with DMBA and promotion with TPA or by repeated dosing with DMBA. TNF-alpha(-/-) mice developed 5-10% the number of tumors developed by wild-type mice during initiation/promotion and 25% of those in wild-type mice after repeated carcinogen treatment. TNF-alpha could influence tumor and stromal cells during tumor development. The early stages of TPA promotion are characterized by keratinocyte hyperproliferation and inflammation. These were diminished in TNF-alpha(-/-) mice. TNF-alpha was extensively induced in the epidermis, but not the dermis, in TPA-treated wild-type skin, indicating that dermal inflammation is controlled by keratinocyte TNF-alpha production. Deletion of a TNF-alpha inducible chemokine also conferred some resistance to skin tumor development. TNF-alpha has little influence on later stages of carcinogenesis, as tumors in wild-type and TNF-alpha(-/-) mice had similar rates of malignant progression. These data provide evidence that a pro-inflammatory cytokine is required for de novo carcinogenesis and that TNF-alpha is important to the early stages of tumor promotion. Strategies that neutralize TNF-alpha production may be useful in cancer treatment and prevention.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1999

A method for foetal heart rate monitoring during magnetic resonance imaging using Doppler ultrasound.

A means of monitoring foetal heart rate (FHR) during magnetic resonance imaging (MRI) is presented. Foetal heart rate was measured using a modified standard Doppler ultrasound based monitor. The transducer and lead from the monitor required alteration to reduce interference and distortion in the MR images to acceptable levels. These changes enabled high quality images to be produced with insignificant additional noise and distortion when the foetal heart rate was recorded simultaneously.

Equipment Safety↗

PubMed1999

Intra-oral temperature variation over 24 hours.

This study aimed to investigate temperature variation at archwire sites adjacent to the maxillary right central incisor and first premolar, its correlation with ambient temperature, and the influence of inter-racial variation. Twenty young adult male subjects were randomly selected (13 Asian, seven Caucasian). Thermocouples were attached to the labial archwire component of custom-made orthodontic retainers at the two intra-oral sites. A third thermocouple measured ambient temperature. A data-logger recorded temperatures at 5-second intervals over a 24-hour period. Temperatures ranged from 5.6 to 58.5 degrees C at the incisor and from 7.9 to 54 degrees C at the premolar, with medians of 34.9 degrees C and 35.6 degrees C, respectively. Ambient temperature correlated poorly with the intra-oral temperatures. The Asian and Caucasian groups had significantly different temperature distributions. On average during the 24-hour period, temperatures at the incisor site were in the range of 33-37 degrees C for 79 per cent of the time, below it for 20 per cent, and above it for only 1 per cent of the time. Corresponding figures for the premolar site were 92, 6, and 2 per cent. At both archwire sites the most frequent temperatures were in the range of 35-36 degrees C. The data presented demonstrate that the temperature at sites on an archwire in situ varies considerably over a 24-hour period and that racial differences may exist. This information should be considered during the manufacture and use of temperature-sensitive orthodontic materials, in particular nickel-titanium archwires and springs.

Adult↗

PubMed1999

Assessment of fetal lung growth in utero with echo-planar MR imaging.

PURPOSE: To measure changes in normal fetal lung volume with increasing gestation by using echo-planar magnetic resonance (MR) imaging. MATERIALS AND METHODS: Fifty-six singleton fetuses were examined longitudinally with respect to lung volume by using echo-planar MR imaging between 19 weeks gestation and term. RESULTS: Lung volume increased exponentially with gestation from 8 to 125 mL. Volume was related to gestation by using the equation, volume = 0.8375e0.1249g (R2 = 0.77), where g = gestation. Lung volume had a direct relationship to fetal volume with increasing gestation (R2 = 0.75). There was no significant relationship between amniotic fluid volume and lung volume (R2 = 0.11). CONCLUSION: Variation in lung volumes can be assessed by using echo-planar MR imaging, regardless of variations in amniotic fluid volume. These measurements are less than those obtained from postmortem and neonatal studies but are similar to those obtained by using three-dimensional ultrasonography. Lung volume estimations obtained by using echo-planar imaging may have important clinical and research applications when noninvassive assessment of lung volume is required.

Adult↗

PubMed1999

Discordance between bone turnover and bone loss: effects of aging and ovariectomy in the rat.

Mechanical strain maintains bone architecture even under conditions of increased bone turnover such as occurs with ovarian hormone deficiency. The rat distal femur contains two sites that apparently experience different levels of mechanical strain and therefore the rat is a suitable model for investigating such effects. The femoral epiphysis experiences higher strain energy compared with the metaphysis and we report the effects of aging between 7 and 12 months and the postovariectomy effects over the same time period on cancellous bone variables measured at these two sites. Age-related bone loss in sham-operated (Sham) animals occurred in both regions, with a greater fall in the metaphysis than in the epiphysis (trabecular bone volume [BV/TV, %] Mean [SEM] Metaphysis: day 0, 25. 9 [2.4]; day 150, 8.8 [1.3]: Epiphysis: day 0, 44.8 [1.7]; day 150, 36.7 [1.4] [p < 0.0001]). With ovariectomy (OVX) there was a 73% reduction in cancellous bone at the metaphysis compared with no specific loss at the epiphysis (BV/TV [%] OVX: Metaphysis: day 150, 2.4 [0.4] [p < 0.01 compared with Sham]: Epiphysis: day 150 29.3 [2. 7] [NS]). Osteoblast cell activity and osteoclast surface were increased after ovariectomy in both regions. The mineral apposition rate decreased at 9.5 months of age in both regions (p < 0.0001), independent of ovariectomy, and was coincident with a reduction in trabecular number in the epiphyses of both operative groups and in the metaphysis of the ovary-intact group. These data suggest that local mechanical strain governs bone balance with aging and that architectural changes resulting from age-related bone loss may mirror those following estrogen deficiency but occur via a different cellular mechanism.

Aging↗

PubMed1998

Osteoclast-mediated bone resorption is stimulated during short-term administration of granulocyte colony-stimulating factor but is not responsible for hematopoietic progenitor cell mobilization.

The cellular and molecular mechanisms responsible for hematopoietic progenitor cell (HPC) mobilization from bone marrow (BM) into peripheral blood after administration of cytokines such as granulocyte colony-stimulating factor (G-CSF) are still unknown. In this study we show that high concentrations of soluble calcium induce the detachment of BM CD34(+) HPC adherent on fibronectin, a major component of BM extracellular matrix. Because G-CSF has been shown to induce osteoporosis in patients with congenital neutropenia and in G-CSF-overexpressing transgenic mice, we hypothesized that short-term G-CSF administration may be sufficient to induce bone resorption, resulting in the release of soluble calcium in the endosteum leading in turn to the inhibition of attachment to fibronectin and the egress of HPC from the BM. We show herein that in humans, serum osteocalcin concentration, a specific marker of bone formation, is strongly reduced after 3 days of G-CSF administration. Furthermore, in patients mobilized with G-CSF either alone or in association with stem cell factor or interleukin-3, the reduction of serum osteocalcin is significantly correlated with the number of HPC mobilized in peripheral blood. Urine levels of deoxypyridinoline (DPyr), a specific marker of bone resorption, gradually elevated during the time course of G-CSF administration until day 7 after cessation of G-CSF, showing a simultaneous stimulation of bone degradation during G-CSF-induced HPC mobilization. In an in vivo murine model, we found that the number of osteoclasts was dramatically increased paralleling the elevation of DPyr after G-CSF administration. When pamidronate, an inhibitor of osteoclast-mediated bone resorption, was administered together with G-CSF in mice, the G-CSF-induced increase of DPyr levels was completely abolished whereas the numbers of colony-forming cells mobilized in peripheral blood were not decreased, but unexpectedly increased relative to the numbers elicited by G-CSF alone. Collectively, our data therefore show that short-term administration of G-CSF induces bone degradation by a simultaneous inhibition of bone formation and an enhanced osteoclast-mediated bone resorption. This increased bone resorption is inhibited by pamidronate without reducing G-CSF-induced HPC mobilization, suggesting that the activation of bone resorption after G-CSF administration is not the direct cause of HPC mobilization as initially hypothesized, but a parallel event.

Adult↗