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Biomedical subjects

R D Ellis

Publications and source records attributed to R D Ellis.

At least 37 records · Page 2Linked to original sources
PubMed1986

Differences between the effects of noradrenaline and the beta-adrenoceptor agonist BRL 28410 in brown adipose tissue and hind limb of the anaesthetized rat.

In mature (450-600 g) 21 degrees C-acclimated male rats, anaesthetized with urethane, blood flow (measured by the radioactive microsphere technique) to brown adipose tissue (BAT) was determined during the infusion of the beta-adrenoceptor agonist BRL 28410 or noradrenaline bitartrate at doses chosen to give similar increases in whole body oxygen uptake. Blood flow to BAT during BRL 28410 infusion was only about one third of that found during noradrenaline infusion although increases in whole body thermogenesis were similar (55 and 77% for BRL 28410 and noradrenaline, respectively). This suggests that BAT may be less involved in the thermogenic response to BRL 28410 than to noradrenaline. In a separate experiment using slightly smaller rats (350-500 g) hind limb oxygen uptake was measured in situ using a venous bypass preparation. BRL 28410, at a dose having a maximum effect on whole body thermogenesis (53% increase), had no effect on oxygen delivery to the hind limb but significantly increased oxygen extraction by 33% (p less than 0.001). In contrast, noradrenaline, also at a dose that maximally increased whole body thermogenesis, led to a 35% decrease in oxygen delivery to the hind limb and no change in oxygen extraction. For the thermogenic beta-agonist BRL 28410 the hind limb, and presumably muscular tissue in general, may be contributing to thermogenesis.

Adipose Tissue, Brown↗
PubMed1984

Treatment of obesity with thermogenic beta-adrenoceptor agonists: studies on BRL 26830A in rodents.

Studies on BRL 26830A in rodents have shown that thermogenic beta-adrenoceptor agonists have potential for the therapy of obesity. BRL 26830A reduced body weight gain in ob/ob mice and fa/fa rats by reducing lipid accumulation. It had no effect on lean body mass. BRL 26830A did not reduce food intake, its anti-obesity effect being due to stimulation of energy expenditure. This thermic effect was enhanced in the obese animals by repeat dosing. BRL 26830A did not affect body weight gain in the lean counterparts of the obese animals because its thermic effect in lean animals was reduced by repeat dosing. Brown adipose tissue is an important site of BRL 26830A-induced thermogenesis. A single dose of BRL 26830A raised brown adipose tissue temperature, depleted brown adipose tissue lipid and unmasked GDP-binding sites in brown adipose tissue mitochondria. Repeat dosing caused hypertrophy of brown adipose tissue and improved cold tolerance in mice. In-vitro studies showed that the rat brown adipocyte beta-adrenoceptor does not fall into the beta 1/beta 2 classification and BRL 28410, which mediates the biological effects of BRL 26830A in vivo, selectively stimulated the brown adipocyte receptor. It is concluded that BRL 26830A achieves its anti-obesity effect by mimicking natural mechanisms involved in thermogenesis and the control of body weight.

Adipose Tissue, Brown↗
PubMed1982

Cyclic GMP in urine to monitor the response to ovarian cancer to therapy.

Guanosine 3':5'-phosphate (cycle GMP) in urine has been used to monitor the response of patients with ovarian cancer to treatment. Changes in the cyclic GMP level appear to correlate well with clinical status in that the disappearance of clinically detectable tumour is associated with a drop in the level whereas a tumour recurrence is associated with an elevation. Serially measured cyclic GMP is valuable for detecting a recurrence of tumour growth in patients in clinical remission and can predate any clinical signs by as much as 10 months. In patients who show no response to treatment, cyclic GMP levels in urine are elevated in the majority of specimens collected.

Creatinine↗
PubMed1982

Urine cyclic nucleotide concentrations in cancer and other conditions; cyclic GMP: a potential marker for cancer treatment.

Cyclic guanosine 3',5' monophosphate (cyclic GMP) and cyclic adenosine 3',5' monophosphate (cyclic AMP) have been determined in random urine specimens from 95 healthy individuals, 60 patients with non-cancerous conditions, 52 patients with benign tumours, and 74 patients with malignant tumours. Concentrations of cyclic GMP have also been determined in a number of other groups, including some undergoing cancer treatment. Ninety-three per cent of cancer patients had raised urinary cyclic GMP concentrations compared to the reference range for healthy subjects. For the non-cancerous and benign groups, 33% and 42% respectively had raised concentrations. The urine cyclic AMP concentrations were similar in all groups. Urine cyclic GMP appeared to rise early in the onset of malignant growth. Successful cancer treatment was accompanied by a dramatic fall in the urine cyclic GMP concentrations, whereas if the treatment was unsuccessful the level did not change. It is concluded that urine cyclic GMP may have important applications in the monitoring of cancer treatment.

Adolescent↗
PubMed1982

Levels of adenosine 3',5' cyclic monophosphate and guanosine 3',5' cyclic monophosphate in single urine specimens collected from a large population of healthy subjects.

The levels of adenosine 3',5' cyclic monophosphate and guanosine 3',5' cyclic monophosphate have been measured in random urine specimens provided by 95 healthy volunteers with a view to assessing the importance of the effects of certain physiological factors on the cyclic nucleotide levels in this type of specimen, and to establish suitable reference ranges for future patient monitoring studies. Of the factors investigated, only the stage of the menstrual cycle was found to have a significant effect; even this variation was still within the overall normal reference range. Measurements of urine cyclic nucleotides were also made in relation to the method of specimen collection, handling, and storage. From these studies it was concluded that if the specimen is placed in a refrigerator within a few hours of collection and then transferred to a deep-freeze within 48 hours, these factors do not present any major problems for the subsequent assay of the cyclic nucleotides.

Adult↗
PubMed1980

Changes in tissue morphology and collagen composition during the repair of cortical bone in the adult chicken.

UNLABELLED: An animal model was developed to study the histology and collagen chemistry of healing cortical bone. A hole was cut through the cortex of the mid-shaft of the humerus of the adult chicken, which allowed for repair at a mechanically stable site. After one to two weeks the collagen of the repair tissue, which consisted principally of woven bone, contained almost three times as much hydroxylysine as the collagen of normal adult bone and thus resembled the collagen of embryonic long bones. By eight weeks, when lamellar one predominated, the hydroxylysine content had fallen to normal levels. Type I was the major genetic type of collagen present throughout. No type-II collagen, characteristic of cartilage, was detected; this was consistent with the histological findings. The results established that hydroxylysine-rich type-I collagen can be made by osteoblasts of adult animals as well as by those of embryos and early postnates. CLINICAL RELEVANCE: In order to understand the biological characteristics of fracture healing, it is vital to study not only the macroscopic organization of the repair tissue but also the chemical properties of its molecular components. The strength of healing fractured bone, and indeed of normal bone, depends largely on the properties of the structural protein collagen. To date, it is not known whether the collagen in healing fractures is the same as that in normal bone, or whether it has distinct chemical features that may suit it for bone repair.

Animals↗
PubMed1977

Use of employment criteria for measuring the effectiveness of methadone maintenance programs.

If employment is to be considered a criteria of success in the treatments of drug abuse, it is necessary to obtain an understanding of the differences in results produced by various measures of employment and the implications of each for evaluating program effectiveness. This article compares three measures by which to analyze chronological employment data for the same cohort of clients across the same time period. It discusses the merits and limitations of these measures as evaluation tools. The findings derive from a study of male clients who were maintained for 2 or more years without interruption in a methadone maintenance program.

Adult↗
PubMedDate not supplied

Paraparesis after posterior spinal fusion in neurofibromatosis secondary to rib displacement: case report and literature review.

In patients with neurofibromatosis, rib displacement into the spinal canal is a rare cause of paraplegia. We report a patient with paraplegia caused by rib displacement whose signs and symptoms began after posterior in situ fusion for dysplastic scoliosis. There was complete recovery after anterior decompression and resection of the rib.

Adolescent↗
PubMedDate not supplied

Slipped capital femoral epiphysis: an analysis of 80 patients as to pin placement and number.

A retrospective study of 80 patients with chronic slipped capital femoral epiphysis was performed, analyzing the clinical results with regard to pin placement and pin number. Follow-up averaged greater than 2 years, with 86% of the 80 patients obtaining a satisfactory clinical outcome. Serious complications occurred in 10 patients. The severity of complications increased as the number of pins used increased (p less than 0.07). A varus pin position resulting in a more inferior pin placement in the proximal femoral epiphysis was found to be associated with the fewest complications. When the pin tip avoided the superior and anterior quadrants in the proximal femoral epiphysis and was greater than 2.5 mm away from subchondral bone, the complication rate was decreased (p less than 0.003).

Adolescent↗
PubMedDate not supplied

Magnetic resonance imaging study of acetabular morphology in developmental dysplasia of the hip.

Acetabular morphology in developmental dysplasia of the hip (DDH) can be delineated by magnetic resonance imaging (MRI) more accurately than by previously available imaging methods. We describe the acetabular morphology observed in 10 girls and one boy aged < 3 years with untreated DDH. The bony pathology was iliac bone widening with lateral drift of the superior and posterior portions of the acetabular floor (extrusio acetabulae), loss of sphericity, and diminished aperture of the acetabulum. The cartilage changes were a distortion and overgrowth of the acetabular cartilage, including labrum, and a convex appearance of the posterior portion of the acetabular cartilage.

Acetabulum↗
PubMedDate not supplied

Acetabular changes in an experimental model of developmental dysplasia of the hip (DDH).

We wished to correlate the morphological acetabular changes in developmental dysplasia of the hip (DDH) with changes at the tissue level. A secondary aim was to develop a way of measuring the dysplastic acetabulum. We studied the changes in rabbit acetabula after maintaining knee extension, measuring the major diameter from the acetabular notch to the farthest opposite point on the acetabular margin. The minor diameter was at right angles to this. The dysplastic acetabula showed elongation along the major diameter compared to control hips. Microscopic sections were made along major and minor diameters. The posterosuperior lip of the dysplastic acetabulum showed an early eversion of the acetabular cartilage. Growth of the articular cartilage in this new direction accounted for the acetabular elongation. As well as providing insight into the manner of acetabular shape change, the findings suggest the nature of remodeling required before normal acetabular growth can resume during treatment.

Acetabulum↗