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Biomedical subjects

G M Hall

Publications and source records attributed to G M Hall.

At least 19 recordsLinked to original sources
PubMed2002

Male jeffrey pine beetle, Dendroctonus jeffreyi, synthesizes the pheromone component frontalin in anterior midgut tissue.

The male Jeffrey pine beetle, Dendroctonus jeffreyi Hopkins (Coleoptera: Scolytidae), produces the bicyclic ketal frontalin as part of a complex semiochemical blend. A key regulated enzyme in the mevalonate pathway, 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-R), showed high transcript levels in the anterior midgut of male Jeffrey pine beetles by in situ hybridization. HMG-R expression in this area of the alimentary canal was related to male emergence, where emerged males demonstrated significant up-regulation of HMG-R transcript and pre-emerged males showed only basal levels. Pre-emerged males were induced to express high levels of HMG-R transcript by treatment with juvenile hormone (JH) III. Additionally, isolated anterior midgut tissue from JH III-treated males converted radiolabeled acetate to frontalin, as assayed by radio-HPLC, providing strong evidence that this is the site of frontalin production in male beetles.

Acetates↗
PubMed2002

Osteocalcin and the hormonal, inflammatory and metabolic response to major orthopaedic surgery.

Plasma osteocalcin, a marker of osteoblastic activity, decreases after major abdominal and gynaecological surgery. Increased cortisol secretion and other hormonal and inflammatory components of the peri-operative stress response may play a role in mediating this response. We assessed the effects of three different anaesthetic techniques on peri-operative osteocalcin concentrations. Thirty-six female patients undergoing elective total hip replacement were randomly assigned to receive propofol, propofol plus 'three-in-one' block or etomidate as part of a general anaesthetic technique. We measured plasma osteocalcin and serum cortisol, bone specific alkaline phosphatase, interleukin-6, plasma epinephrine, norepinephrine, plasma glucose and cystatin C concentrations for up to 3 days after surgery. Etomidate successfully inhibited the cortisol response to surgery but plasma osteocalcin declined in all patients. This was accompanied by increased plasma catecholamines, interleukin-6 and glucose concentrations, and decreased cystatin C-values. Inhibition of the cortisol response to surgery failed to prevent a decrease in plasma osteocalcin concentrations after surgery, suggesting that other factors such as cytokines or catecholamines may play a significant role.

Aged↗
PubMed2002

The time course of the human growth hormone response to a 6 s and a 30 s cycle ergometer sprint.

Exercise is a potent stimulus for the release of human growth hormone (hGH), but the time course of the hGH response to sprint exercise has not been studied. The aim of the present study was to determine the time course of the hGH response to a 6 s and a 30 s maximal sprint on a cycle ergometer. Nine males completed two trials, on one occasion performing a single 6 s sprint and on another a single 30 s sprint. They then rested on a couch for 4 h while blood samples were obtained. Three of the participants completed a further control trial involving no exercise. Metabolic responses were greater after the 30 s sprint than after the 6 s sprint. The highest measured mean serum hGH concentrations after the 30 s sprint were more than 450% greater than after the 6 s sprint (18.5 +/- 3.1 vs 4.0 +/- 1.5 microg l(-1), P < 0.05). Serum hGH also remained elevated for 90-120 min after the 30 s sprint compared with approximately 60 min after the 6 s sprint. There was a large inter-individual variation in the hGH response to the 30 s sprint. In the control trial, serum hGH concentrations were not elevated above baseline at any time. It would appear that the duration of a bout of maximal sprint exercise determines the magnitude of the hGH response, although the mechanism for this is still unclear.

Adolescent↗
PubMed2002

Parkinson's disease and anaesthesia.

Parkinson's disease is an increasingly common disease of elderly patients who present a particular anaesthetic challenge. This review explores the epidemiology, aetiology, pathogenesis, and pathophysiology of the condition, particularly the possible role of genetic factors. The clinical features are described in detail and recent advances in medical management are highlighted. Controversies surrounding the use of the newer drugs and possible advances in neurosurgical interventions are discussed. Particular anaesthetic problems in patients with Parkinson's disease are respiratory, cardiovascular, and neurological. Potential drug interactions are described and recommendations are made about suitable anaesthetic techniques.

Anesthesia↗
PubMed2002

Mandibular fracture patterns in Tasmania, Australia.

BACKGROUND: No previous studies on mandibular fracture patterns in Tasmania, and very few elsewhere in Australia, have undertaken to discover which identified age, gender, aetiology, anatomical location of the fracture, period of injury, whether alcohol consumption was associated with the injury, and treatment of mandibular fractures. METHOD: A retrospective study was undertaken of 251 patients with fractured mandibles presenting to the Royal Hobart Hospital, Tasmania from 1993-1999. Data were obtained from the Oral and Maxillofacial Surgery unit fracture record books cross-checked with patients, impatient/outpatient hospital records. RESULTS: The male to female ratio was 4.5:1, with mandibular fractures most common in the male age group of 21-30 years. Assaults (55 per cent of all patients) were the major cause of fractures. Males accounted for 85.5 per cent of assaults, with punching being the most common method, followed by motor vehicle accidents (MVA), 18.3 per cent and sport, 16.7 per cent. In sport, Australian Rules Football was the most common cause, accounting for 45.2 per cent of sporting injuries. The site most frequently fractured was the angle of the mandible. Alcohol abuse was seen in 41.4 per cent of the patients with 84.6 per cent being male. Open reduction and internal fixation with miniplate osteosynthesis, was the preferred treatment modality. The results are compared with other series. CONCLUSIONS: Mandibular fractures are common in Tasmania, with the highest rates involved in assaults and sport (especially Australian Rules Football) and a low rate in MVA. These fractures commonly occurred in young males in which assaults, alcohol and social issues were associated. Therefore, preventive measures and strong public awareness addressing this group may be of benefit in reducing the rate of assaults and sporting injuries to the mandible.

Accidents, Traffic↗
PubMed2002

Growth hormone responses to repeated maximal cycle ergometer exercise at different pedaling rates.

The present study examined the growth hormone (GH) response to repeated bouts of maximal sprint cycling and the effect of cycling at different pedaling rates on postexercise serum GH concentrations. Ten male subjects completed two 30-s sprints, separated by 1 h of passive recovery on two occasions, against an applied resistance equal to 7.5% (fast trial) and 10% (slow trial) of their body mass, respectively. Blood samples were obtained at rest, between the two sprints, and for 1 h after the second sprint. Peak and mean pedal revolutions were greater in the fast than the slow trial, but there were no differences in peak or mean power output. Blood lactate and blood pH responses did not differ between trials or sprints. The first sprint in each trial elicited a serum GH response (fast: 40.8 +/- 8.2 mU/l, slow: 20.8 +/- 6.1 mU/l), and serum GH was still elevated 60 min after the first sprint. The second sprint in each trial did not elicit a serum GH response (sprint 1 vs. sprint 2, P < 0.05). There was a trend for serum GH concentrations to be greater in the fast trial (mean GH area under the curve after sprint 1 vs. after sprint 2: 1,697 +/- 367 vs. 933 +/- 306 min x mU(-1) x l(-1); P = 0.05). Repeated sprint cycling results in an attenuation of the GH response.

Adult↗
PubMed2001

Postoperative fatigue is a component of the emotional response to surgery: results of multivariate analysis.

OBJECTIVE: To test the theory that postoperative fatigue is an aspect of the emotional, not physiological, response to surgery, we examined whether fatigue is a component of subjective experience after surgery and whether it is related to subjective physical or emotional state. METHODS: Patients (N=160) undergoing hip or knee arthroplasty were assessed preoperatively, 1 and 7 days and 1 and 6 months postoperatively using multiple indicators of fatigue and subjective emotional and physical state. Covariance structure modeling was used to find out the structure of patients' experience on each occasion. RESULTS: At each time, data indicated four latent variables: negative mood, positive mood, dysfunction and pain. Scales measuring fatigue indicated negative or positive mood but were unrelated to dysfunction and pain. DISCUSSION: In surgical patients, the language of fatigue and energy describes empirically distinct components of emotional state. Explanations for postoperative fatigue should therefore be sought in emotional, not physiological, mechanisms.

Affect↗
PubMed2001

Influence of the emotional response to surgery on functional recovery during 6 months after hip arthroplasty.

We examined whether the emotional response to hip arthroplasty predicted functional recovery after controlling for preoperative function and surgical trauma. Mood and fatigue were measured in 102 consecutive patients preoperatively and 3 days postoperatively. Time of achievement of functional milestones indicated recovery in hospital, and functional status was measured preoperatively and 1 and 6 months postoperatively. Circulating C-reactive protein and interleukin-6 levels indicated trauma. Recovery in hospital was slower in patients with greater trauma. Recovery at follow-up was slower in patients with poorer preoperative function and with greater anxiety and fatigue, but the apparent influence of anxiety was explained by its association with preoperative function and fatigue. Whereas short-term recovery is predicted by surgical trauma, long-term recovery is predicted by preexisting function and the emotional response to surgery. However, the influence of the emotional response is small and the important aspect of emotion is fatigue rather than anxiety.

Aged↗
PubMed2001

Recovery from hip and knee arthroplasty: Patients' perspective on pain, function, quality of life, and well-being up to 6 months postoperatively.

OBJECTIVE: To provide a more detailed description from patients' perspectives than is yet available of recovery from hip and knee arthroplasty and to use this information to test 2 assumptions about recovery from these procedures: that recovery from knee arthroplasty, as assessed by patients, routinely reaches the level achieved by hip arthroplasty; and that fatigue is prolonged after major orthopedic surgery. DESIGN: A cohort study. SETTING: University teaching hospitals. PARTICIPANTS: Consecutive patients undergoing hip (n = 107) or knee (n = 53) arthroplasty. INTERVENTIONS: Unilateral hip or knee arthroplasty. MAIN OUTCOME MEASURES: Standardized self-rated measurements of pain, function, quality of life, and well-being from preoperatively to 6 months follow-up. RESULTS: Pain and function improved significantly less after knee arthroplasty than after hip arthroplasty, but the 2 procedures led to similar improvements in life evaluation, mood, and subjective health. Fatigue was only transiently increased. CONCLUSION: The findings were inconsistent with both assumptions. Nevertheless, despite poorer recovery in pain and function, patients receiving knee arthroplasty felt that life had improved as much as did patients with hip arthroplasty. Detailed information about how major joint arthroplasty in routine practice affects patients' lives can be used to advise patients and clinicians and can invalidate influential, but inaccurate, assumptions.

Activities of Daily Living↗
PubMed2001

Epidural analgesia and arterial reconstructive surgery to the leg: effects on fibrinolysis and platelet degranulation.

It has been suggested that the incidence of early graft occlusion after arterial reconstructive surgery to the leg may be decreased by epidural analgesia. This effect may be mediated by the suppression of the usual cortisol response to surgery, which results in increased circulating plasminogen activator inhibitor-1 with consequent adverse effects on fibrinolysis. To investigate this and other potential mechanisms, 30 patients undergoing arterial reconstructive surgery to the leg were randomized to receive either general anaesthesia or general anaesthesia plus epidural analgesia. Post-operative analgesia was provided by morphine infusion or epidural analgesia, respectively. Blood samples were collected at 0, 2, 4, 6, 12 and 24 h, and 2, 3 and 5 days and analysed for cortisol, plasminogen activator inhibitor-1 antigen, interleukin-6 and beta thromboglobulin. The incidence of graft-related and systemic complications was recorded for 30 days. Only one patient developed early graft occlusion that required embolectomy and eventually amputation. There were no significant changes from control values in either group of patients in circulating cortisol, plasminogen activator inhibitor-1 and beta thrombogobulin (a marker for platelet degranulation). Interleukin-6 values increased significantly in both groups after 4 h and remained elevated until day 3. There were no significant differences between the groups in any variable measured. We conclude that any effect of epidural analgesia on early graft patency is unlikely to be mediated by fibrinolysis or platetlet degranulation.

Aged↗
PubMed2001

Effects of dexmedetomidine on adrenocortical function, and the cardiovascular, endocrine and inflammatory responses in post-operative patients needing sedation in the intensive care unit.

We have compared the effects of dexmedetomidine and propofol on endocrine, metabolic, inflammatory and cardiovascular responses in patients in the intensive care unit (ICU) after major surgery. Twenty patients who were expected to require 8 h of post-operative sedation and ventilation were allocated randomly to receive either an infusion of dexmedetomidine 0.2-2.5 microg kg(-1) h(-1) or propofol 1-3 mg kg(-1) h(-1). Arterial pressure, heart rate and sequential concentrations of circulating cortisol, adrenocorticotrophic hormone (ACTH), growth hormone, prolactin, insulin, glucose and interleukin 6 were measured. An ACTH stimulation test was performed in all patients who received dexmedetomidine. Heart rate was significantly lower in the dexmedetomidine patients. There were no differences in arterial pressure, cortisol, ACTH, prolactin and glucose concentrations between the two groups. A positive response to the ACTH stimulation test varied depending on the diagnostic criteria used. The insulin concentration was significantly lower in the dexmedetomidine group at 2 h (P=0.021), although this did not affect blood glucose concentrations. Growth hormone concentrations were significantly higher in dexmedetomidine-treated patients overall (P=0.036), but circulating concentrations remained in the physiological range. Interleukin 6 decreased in the dexmedetomidine group. We conclude that dexmedetomidine infusion does not inhibit adrenal steroidogenesis when used for short-term sedation after surgery.

Adrenal Cortex↗
PubMed2001

Relationship of the functional recovery after hip arthroplasty to the neuroendocrine and inflammatory responses.

We studied the relationship between the neuroendocrine and inflammatory responses to hip arthroplasty and functional recovery in 102 patients undergoing elective arthroplasty for osteoarthritis. Blood samples were collected for up to 7 days after surgery and analysed for concentrations of norepinephrine, epinephrine, cortisol, interleukin-6 and C-reactive protein. The primary outcome measures were milestones in hospital, times to walk 10 and 25 m, pain on discharge from hospital, and function 1 and 6 months after surgery. Walking distances in hospital were significantly delayed in patients with greater interleukin 6 and C-reactive protein concentrations, but few neuroendocrine measures had significant correlations with functional recovery in hospital. Multivariate analysis showed that the interleukin 6 concentration on day 1 was the unique predictor of time to walk 10 and 25 m, and that the day 2 concentration of C-reactive protein was the unique predictor of pain on discharge from hospital. No significant correlations were found between the inflammatory and neuroendocrine variables and recovery at 1 and 6 months. We conclude that the inflammatory response affects immediate functional recovery after hip arthroplasty.

Adult↗