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Biomedical subjects

P Davison

Publications and source records attributed to P Davison.

At least 19 recordsLinked to original sources
PubMed2005

The relationship between potentially erosive storm energy and daily rainfall quantity in England and Wales.

Erosive storm energy is the primary driver of soil detachment, and hence a major determinant of transfer of sediment and particulate phosphorus (P) to surface waters. Modelling of sediment and P loss at catchment scale, for example for the development of catchment and national mitigation policies, requires a spatially interpolated estimate of variation in erosion risk. To this end we present a method of estimating total rainfall erosivity, as kinetic energy (KE), for any location in England and Wales, from daily rainfall data or monthly climate data. Analysis of detailed, high-resolution records from eleven contrasting sites showed strong predictive correlations between daily rainfall quantity and associated daily total kinetic energy estimated from hourly rainfall intensities. The coefficients showed systematic seasonal variation, with greatest KE per unit of rainfall in late summer and autumn months. In contrast, no systematic spatial variation was found as a function of location or continentality index. The relationships were integrated with probability distributions of rainfall quantity per rain day derived from spatial climate data (monthly rainfall totals and numbers of rain days). The resulting map captures and quantifies the effects of rainfall quantity and intensity patterns on risk of sediment detachment, and as such provides a critical input layer to catchment-scale models of sediment and P transfer.

England↗
PubMed2000

ACC/AHA guidelines as predictors of postoperative cardiac outcomes.

PURPOSE: Recently, the American College of Cardiology - American Heart Association (ACC-AHA) published guidelines and an associated algorithm for preoperative cardiovascular evaluation of patients undergoing non-cardiac surgery. Our purpose was to (i) test guideline's ability to predict adverse cardiac events within seven days after surgery, (ii) determine whether medical clinical predictors or surgical risks was a better predictor of cardiac events. METHODS: Retrospective review of 119 cardiology and anesthesia consultations over 15 mo, ending March 31, 1998. Patients were classified into their respective medical clinical predictor and surgical risk groups, as outlined in ACC-AHA guidelines. Associations between the medical predictor and surgical risk scores and adverse cardiac outcomes were quantified via multiple logistic regression analysis. Two outcomes were employed. Outcome I, included: myocardial infarction/ischemia; angina; congestive heart failure, arrhythmia or death. Outcome 2 expanded the definition to include "cancellation of surgery due to cardiac risk" as a negative cardiac outcome. RESULTS: Diabetes, Canadian Cardiovascular Class (CCS) III or IV angina, and MI within six months before surgery were strongly associated with the two cardiac outcomes. For outcome 1 and 2, medical predictors and surgical risks, considered simultaneously, performed with a sensitivity of 93% and specificity of 46-51%. When considered separately, major clinical medical predictors had a sensitivity of 87-89%, while surgical risks showed a specificity of 89% in predicting the two outcomes. CONCLUSION: Medical predictors in ACC-AHA classification scheme were highly sensitive whereas surgical risks were more specific in predicting adverse post-operative cardiac events. Prospective study is needed to confirm these observations.

Adult↗
PubMed1999

Esophageal atresia: primary repair of a rare long gap variant involving distal pouch mobilization.

This report describes a rare type IIIb variant of long gap pure esophageal atresia treated with delayed primary repair. Preoperative imaging showed a distal pouch with a unusually long tapering end, and a 5-vertebral body gap. Delayed exploration with mobilization of the distal pouch allowed for successful primary repair without the need of myotomy. The characteristic radiological appearance of this rare variant enables its preoperative recognition and warrants attempting primary repair with a good expectation of success.

Adult↗
PubMed1999

"Wheelchair" patients with nonorganic disease: a psychological inquiry.

We studied ten patients referred from the neurology service with severe disability associated with the use of a wheelchair, but with no organic disorder to account for their disabilities. All patients were assessed using rating scales as well as a standardized psychiatric interview (SCID), and all medical and psychiatric case notes were examined. We also interviewed key carers for their views on the information and assistance the patients had received. All but two of the ten patients were women, and the mean age was 45.4 years (SD=5.4). All had current diagnoses of conversion or somatoform disorders and six had previous episodes of major depression. Most patients expressed beliefs about their illness that were not consistent with the medical facts, and only two of the carers were satisfied with explanations they had been given by doctors. The results suggest that requests for psychiatric help once patients have become grossly disabled are unlikely to lead to recovery. The psychiatrist, however, can help the primary care doctor to formulate a plan of management aimed at preventing further deterioration.

Adult↗
PubMed1996

Pericardial tamponade and death from Hickman catheter perforation.

In February 1995, a 56-year-old female was taken to the operating room for routine placement of a Hickman catheter. Her internist planned palliative chemotherapy for metastatic breast cancer. Using the Seldinger technique, the right subclavian vein was entered and a Hickman catheter was placed. Shortly after extubation and arrival in the postoperative recovery unit, the patient had respiratory and cardiac arrest. Resuscitative efforts, including chest tube placement and pericardiocentesis, were unsuccessful. Autopsy findings included perforation of the superior vena cava, with extension of the catheter in the pericardial sac and associated effusion. Despite the low reported incidence of perforation during placement of central venous catheters, we recommend confirmation of placement by fluoroscopy and instillation of radiopaque dye because of the high mortality associated with this complication.

Cardiac Tamponade↗
PubMed1994

Informed consent: what do patients want to know?

Informed consent is an important aspect of surgery, yet there has been little inquiry as to what patients want to know before their operation. This study has questioned 50 patients within 3 months of an ENT (ear, nose and throat) operation. We found that most were happy to allow doctors to determine their treatment but they wanted to know about their condition, the treatment, and the important side effects. Fifty per cent of patients admitted worrying about some aspect of their recent surgery. More than two-thirds thought signing a consent form primarily signified agreement to undergo treatment and that it was a legal document; 54% thought there was an important medico-legal aspect. Over half thought information sheets would be reassuring, one-third thought they would provoke anxiety and 8% thought they would frighten them from having surgery. Closer examination of the answers to our questions showed that those who were most worried about aspects of their surgery had a higher mean anxiety score, as did those who thought an information sheet would be either frightening or anxiety provoking. However, a higher anxiety score was not associated with a desire to know less about the proposed treatment.

Adolescent↗
PubMed1993

Acute amitriptyline withdrawal and hyponatraemia. A case report.

The tricyclic antidepressants (TCAs) are commonly used in the treatment of depression and, perhaps due to the nature of the condition being treated, figure prominently in cases of deliberate overdosage, where the toxicity of amitriptyline has been well established. However, the abrupt cessation of TCA administration can also be detrimental to the patient, triggering withdrawal phenomena often characterised by an exacerbation of the symptoms for which the patient was originally treated. We present a biochemically proven case of amitriptyline withdrawal where the clinical features at presentation made it difficult to distinguish from acute toxicity. The patient's neurological signs and distended bladder suggested amitriptyline toxicity, whereas the history and signs of cholinergic hyperactivity were consistent with acute withdrawal. The diagnosis was confirmed at a later date when further history and a biochemical analysis of plasma TCA concentrations became available. Hyponatraemia may have exacerbated the condition of the patient, whether or not it was caused by amitriptyline.

Acute Disease↗
PubMed1990

Single wound produced by simultaneous discharge of both shells from a double-barrel shotgun.

We present the case of a man who was killed by simultaneous discharge of both barrels of a double-barrel shotgun. Externally, there was a single wound simulating a wound made by a discharge of a single barrel. Test-firing of the shotgun against cloth, paper, and naugahyde targets revealed defects similar in shape to the wound in the victim. Simultaneous discharge of both barrels from a double-barrel shotgun may simulate the wound made by discharge of a single barrel.

Adult↗
PubMed1987

Toxic epidermal necrolysis complicating a burn: a case report.

The case of a burned patient, whose fluid management was complicated by the development of toxic epidermal necrolysis, a condition which itself may mimic a burn, is presented. The possible causes, together with the diagnostic and therapeutic problems posed by this combination of ailments, are discussed.

Aged↗
PubMed1987

Viscosity of food gums determined in vitro related to their hypoglycemic actions.

Experiments were carried out in vitro and in normal human subjects to evaluate alternative food-grade viscous polysaccharides as agents for reducing postprandial hyperglycemia and to assess the relationship between the in vitro and in vivo performance of the polysaccharides. A 1:1 mixture of xanthan and locust bean gum (X/LBG) had the greatest viscosity at equivalent concentrations and shear rates and was more effective than guar gum, xanthan, or locust-bean gum at inhibiting glucose movement in vitro. It was not, however, more efficient in lowering postprandial blood glucose and plasma insulin in human subjects when incorporated in a drink containing 50 g glucose. When the different gums were acidified and reneutralized to mimic conditions in the gut, there was a better correlation between viscosity and blood glucose and plasma insulin levels. This effect may explain why X/LBG was no more effective than the other gums in reducing postprandial hyperglycemia in man.

Adolescent↗
PubMed1987

Effect of stool size and consistency on defecation.

The ability of subjects to expel from the rectum objects simulating stools of different characteristics was assessed in paired studies carried out in a total of 58 normal subjects and 25 young women with severe constipation. Our results showed that a lower percentage of normal subjects and a lower percentage of constipated patients were able to pass a 1.8 cm incompressible sphere compared with a 50 ml deformable balloon, although constipated patients found it more difficult than normal subjects to expel both types of simulated stool. It was also more difficult for normal subjects to pass a soft compressible silicon rubber simulated stool than a stool made up of a similar volume of incompressible 1 cm wooden spheres contained in a cylindrical latex envelope, but both objects were much easier to pass than the same number of 1 cm spheres placed loose within the rectum. When normal subjects were instructed to expel single incompressible spheres of different sizes placed in the rectal ampulla, the intrarectal pressure and the time needed to pass these objects varied inversely with their diameter. These results suggest that more effort is required to expel stools from the rectum if they are small and hard than if they are large and soft.

Adult↗
PubMed1986

Histochemical analysis of breast carcinoma metastatic to the orbit.

A 62-year-old woman was seen for evaluation of an orbital tumor. Recognition of a relatively rare syndrome of pain, ptosis, and a progressively immobilized globe with enophthalmos suggested the diagnosis of metastatic carcinoma to the left orbit. In this case, this was confirmed by open breast and orbital biopsies, revealing infiltrating lobular breast carcinoma. This is the first reported case where estrogen and progesterone receptors were identified in a metastatic orbital tumor using fluorescent histochemical techniques. This technique was of value in confirming the diagnosis and providing direction for subsequent endocrinologic palliative therapy.

Biopsy↗
PubMed1979

Limitations in the use of [3H]thymidine incorporation into DNA as an indicator of epidermal keratinocyte proliferation in vitro.

The validity of using the incorporation of [3H]thymidine into DNA as an indicator of epidermal keratinocyte proliferation in vitro has been investigated. Other parameters of cell proliferation, direct count of cell number and measurement of DNA content, consistently fail to correlate with changes in [3H]thymidine incorporation into DNA in primary and first passage cultures of rabbit and human epidermal keratinocytes. Maximum incorporation of [3H]thymidine precedes the active growth period by three days. Incorporation declines markedly during the proliferative period. Thymidine kinase activity decreases during the proliferative growth phase. Incorporation of another pyrimidine nucleotide precursor, [14C]aspartic acid, suggests that in epidermal keratinocytes in vitro the extent of utilization of the salvage and the de novo pathways may be inversely related. In such cases [3H]thymidine incorporation into TCA precipitable material fails to reflect accurately cell proliferation.

Animals↗