Biomedical subjects

C Rawlings

Publications and source records attributed to C Rawlings.

10 recordsLinked to original sources

PubMed2001

Evaluation of colposuspension for treatment of incontinence in spayed female dogs.

OBJECTIVE: To determine the long-term effects of colposuspension in spayed female dogs with urinary incontinence and identify preoperative anatomic or urodynamic measurements associated with a successful outcome. DESIGN: Prospective study. ANIMALS: 23 client-owned spayed female dogs with urinary incontinence. PROCEDURE: Prior to surgery, a history was obtained, and a physical examination, CBC, serum biochemical analyses, urinalysis, bacterial culture of a urine sample, vaginourethrocystography, urethral pressure profilometry, and leak point pressure test were performed. Colposuspension was performed, and preoperative tests were repeated 2 months after surgery. Clients were interviewed 2 weeks, 1 month, and 1 year after surgery. RESULTS: 22 dogs were followed up for 1 year. Twelve had complete urinary control 2 months after surgery, and 3 had complete urinary control 1 year after surgery. Dogs with normal urinary control at 2 months had an increased leak point pressure (LPP), compared with preoperative measurements, and their LPP was the same as normal dogs. Eight dogs had complete urinary control, and 9 were considered greatly improved 1 year after surgery when medical treatment was added to the effect of colposuspension. Client satisfaction was high, with 19 of 22 (86%) owners being pleased with their decision to have surgery performed. The only predictors of complete urinary control 2 months after surgery were a more caudal position of the external urethral opening in relation to the pubis on preoperative radiographs and a longer overall urethral length. CONCLUSIONS AND CLINICAL RELEVANCE: Colposuspension alone will result in complete urinary control in few dogs with urinary incontinence but may improve urinary control sufficiently that owners will be pleased. Preoperative vaginourethrocystography may be helpful in predicting response to surgery, and the LPP test correlates with improved urinary control.

Animals↗

PubMed2001

Are grammatical representations useful for learning from biological sequence data?--a case study.

This paper investigates whether Chomsky-like grammar representations are useful for learning cost-effective, comprehensible predictors of members of biological sequence families. The Inductive Logic Programming (ILP) Bayesian approach to learning from positive examples is used to generate a grammar for recognising a class of proteins known as human neuropeptide precursors (NPPs). Collectively, five of the co-authors of this paper, have extensive expertise on NPPs and general bioinformatics methods. Their motivation for generating a NPP grammar was that none of the existing bioinformatics methods could provide sufficient cost-savings during the search for new NPPs. Prior to this project experienced specialists at SmithKline Beecham had tried for many months to hand-code such a grammar but without success. Our best predictor makes the search for novel NPPs more than 100 times more efficient than randomly selecting proteins for synthesis and testing them for biological activity. As far as these authors are aware, this is both the first biological grammar learnt using ILP and the first real-world scientific application of the ILP Bayesian approach to learning from positive examples. A group of features is derived from this grammar. Other groups of features of NPPs are derived using other learning strategies. Amalgams of these groups are formed. A recognition model is generated for each amalgam using C4.5 and C4.5rules and its performance is measured using both predictive accuracy and a new cost function, Relative Advantage (RA). The highest RA was achieved by a model which includes grammar-derived features. This RA is significantly higher than the best RA achieved without the use of the grammar-derived features. Predictive accuracy is not a good measure of performance for this domain because it does not discriminate well between NPP recognition models: despite covering varying numbers of (the rare) positives, all the models are awarded a similar (high) score by predictive accuracy because they all exclude most of the abundant negatives.

Bayes Theorem↗

PubMed1994

A randomised trial of patient repositioning during radiotherapy using a megavoltage imaging system.

Effectiveness of radiotherapy is dependent on the accuracy of beam alignment. Recent developments in megavoltage imaging allow real-time monitoring of beam placement. Maximum gains from this new technology can only be made if the information is utilised to correct patient positioning prospectively before the majority of a treatment fraction is delivered. We have developed and utilised an integrated megavoltage imaging system to perform a randomised trial demonstrating significant improvements in accuracy using treatment intervention techniques for pelvic radiotherapy. The mean field-placement accuracy improved from 4.3 mm to 2 mm and the proportion of treatments given with a field-placement error of > or = 5 mm decreased from 69% to 7%. This improvement in accuracy may enable smaller margins around the target volume to be chosen whilst ensuring complete target coverage at each treatment fraction.

Aged↗

PubMed1993

Technical note: the implementation of patient position correction using a megavoltage imaging device on a linear accelerator.

The problem of using information from the analysis of megavoltage images to adjust patient set-up has been addressed. In the case of rotational corrections it has been assumed that the treatment head is to be adjusted, although for gantry angles of 0 degree and 180 degrees couch rotation may be used. In the case of translational shifts adjustment of the collimator jaws or of the couch have both been considered for arbitrary combinations of couch and gantry angle. For couch movement the case has been considered where it is desirable to minimize both the number of parameters to be adjusted and also the magnitude of the change in the patient's position. Values obtained for frequently used set-up parameters have been presented. Adjustment of the treatment couch positioning is the most desirable option, as this should bring the patient closer to the correct position for subsequent treatment fields. However, rotational errors are not correctable for all gantry angles and furthermore the collimator settings may be set more accurately than those of the treatment couch. Hence, in some cases, adjustment of the collimation system may be desirable or necessary. The formulae given in Equations (13) to (18) are currently being used in an intervention study to correct patient set-up during the course of a treatment fraction.

Humans↗

PubMed1992

The history of neurosurgical procedures for the relief of pain.

Pain has been a major medical problem from the beginning of recorded history. Since the earliest medical writings, there have been innumerable procedures designed to relieve pain and its suffering. In this study, we have reviewed both the early medical writings of various civilizations and the first modern publications, to compile a history of neurosurgical procedures for the relief of pain.

Analgesia↗

PubMed1992

Image comparison techniques for use with megavoltage imaging systems.

In this paper we describe software facilities for enabling patient positioning studies using the megavoltage imaging system developed at the Royal Marsden Hospital and Institute of Cancer Research. The study focuses on the use of the system for three purposes: patient position verification (by comparing images taken at treatment simulation with megavoltage images taken at treatment time); reproducibility studies (by analysing a set of megavoltage images); and set-up correction (by adjusting the set-up until the megavoltage image obtained at treatment registers with the simulation image). The need is discussed for suitably presented simulator images, a method of determining field boundaries and the possibility of delineating soft-tissue interfaces. Several algorithms of different types, developed specifically for the purpose of intercomparison of planar projection images, are presented. The techniques employed and their usefulness, in both the qualitative and the quantitative sense, are discussed. The results are presented of a phantom and clinical study, to evaluate the rigour and reproducibility of the algorithms. These results indicate that measurements can be made to an accuracy of about 1-2 mm, with a similar value for interobserver reproducibility for the best image comparison techniques available.

Algorithms↗

PubMed1983

Early arterial injury-induced myointimal proliferation in canine pulmonary arteries.

Transmission electron microscopy was used to study the early vascular response induced by arterial damage with heartworm infection. The pulmonary arteries were examined in dogs 4 days after experimental transplantation of 6 to 8 Dirofilaria immitis adults. Evan's blue dye was given IV and followed in 60 minutes by perfusion fixation with 1% glutaraldehyde. Endothelial cell junctions were disrupted and rounded endothelial cells were observed. Macrophages and neutrophils adhered to abnormal endothelial cells. Focal areas had platelet aggregates adhered to exposed subendothelial structures. Platelets were activated and degranulated. Areas of the internal elastic lamina appeared to be disrupted, and smooth muscle cell processes from the tunica media extended through these regions of disruption. Smooth muscle cells were oriented toward the arterial lumen and some had migrated to the surface. These findings are compatible with the response to injury theory of myointimal proliferation.

Animals↗

PubMed1980

Physiologic changes in awake goats after experimentally induced pericardial effusion.

Awake, unmedicated goats were used to study the physiologic effects of experimentally induced acute pericardial effusion. With an increase in pericardial volumes, there was a significant (P < 0.01) linear decrease in the cardiac index. This decrease was apparently due to the decrease in stroke index (P < 0.01) rather than to a decrease in heart rate. Peripheral vascular resistance in both the systemic and pulmonary arteries increased. The aortic pressure initially fell, but later rose with an increase in pericardial volumes. Pulmonary arterial pressures decreased with an increase in pericardial volumes. Pressure in the right atrium were significantly elevated (P < 0.01) with an increase in pericardial volumes.

Animals↗

PubMed1979

Pathophysiologic studies of calves given 3-methylindole intraruminally.

Intraruminal administration of 0.25 g of 3-methylindole (3MI; skatole/kg of body weight) to seven young calves generally caused mild respiratory signs and lesions, accompanied by only slight changes in cardiopulmonary function. Moderate depression, trembling, and irregular respiratory rate were observed between postadministration hours (PAH) 6 and 12. By PAH 24 at this dosage, abnormal clinical signs were not present. Statistically significant (P less than or equal to 0.05) changes observed in blood gas data from the seven calves were a decrease in aortic oxygen tension at PAH 12, increases in free-flowing venous oxygen tension in the intervals between PAH 6 and 12 and between PAH 6 and 24, and an increase in occluded venous oxygen tension at PAH 24. All calves had increases (although generally not statistically significant) in heart rate, cardiac output, cardiac index, stroke volume, and stroke index after 3MI administration. Mean aortic and pulmonary arterial pressure changes were generally small and variable. At necropsy, the lungs of the calves did not collapse when the thorax was opened. Patchy areas of consolidation (0.5 cm in diameter) were scattered throughout the parenchyma. Pulmonary edema or emphysema was not observed grossly. Microscopically, the alveolar septae were irregularly thickened because of edema, infiltration by polymorphonuclear and mononuclear cells, and vascular congestion. Interstitial lesions were patchy in distribution and severity and corresponded to the areas of consolidation observed grossly. Alveolar epithelial hypertrophy and hyperplasia were present, and an occasional focus of alevoli contained fluid of edema. Degeneration of individual hepatocytes was observed in scattered areas of the liver, especially in the periportal areas. It was concluded that differences in 3MI dosage response may exist between young calves and adult cattle in which calves are more resistant to the pulmonary cytotoxicity of 3MI.

Animals↗

PubMed1978

Esophageal deviation in four English Bulldogs.

Regurgitation, vomiting, and aspiration pneumonia in 4 young male English Bulldogs were attributed to esophageal deviation that was demonstrated by esophageal radiography. A genetic relationship among these dogs was not determined. Exploratory thoractomy, performed in 2 dogs, demonstrated an apparent compression of the esophagus by the left subclavian artery and brachiocephalic artery at the level of the 2nd and 3rd intercostal spaces. This apparent compression correlated with the roentgen location of esophageal deviation. Surgical redirection of the left subclavian artery resulted in immediate and long-lasting remission of clinical signs.

Animals↗