Robert Hawker - Academia.edu (original) (raw)

Papers by Robert Hawker

Research paper thumbnail of Improvements in long tendon support with pumpable resin

Long tendon support systems provide several challenges when used as part of the secondary or prim... more Long tendon support systems provide several challenges when used as part of the secondary or primary support cycle. A two-component pumpable resin, Carbothix, has been in development for use with self-drilling rock bolts. Many of the attributes of this new resin system make it ideal for grouting long tendon support systems. While neat Portland cement grouts or polyester resin capsules have been used with long tendon support systems for many years, two-component pumpable resin systems overcome many of the shortcomings in these systems. The two-component systems dramatically improve the set-time to enable mining face advance with fewer delays, enable longer pumping distances, improve quality control, and enhance load transfer mechanisms. This paper describes the key benefits associated with a new pumpable resin and details the Coal Services Health/Workcover atmospheric testing results and cable load testing completed to date. It also details the results of the Australian mine site trials and the introduction of these systems into production use.

Research paper thumbnail of A method to demonstrate inadequate blood component mixing

Nuclear Medicine Communications, 1995

Research paper thumbnail of Long-term Effectiveness of Adjuvant Treatment With Catechol-O-Methyltransferase or Monoamine Oxidase B Inhibitors Compared With Dopamine Agonists Among Patients With Parkinson Disease Uncontrolled by Levodopa Therapy

JAMA Neurology

IMPORTANCE Many people with Parkinson disease (PD) develop motor complications that are uncontrol... more IMPORTANCE Many people with Parkinson disease (PD) develop motor complications that are uncontrolled by levodopa dose adjustment. Among these patients, it is uncertain which drug class is more effective as adjuvant therapy. OBJECTIVE To compare the long-term effects on patient-rated quality of life of adding a dopamine agonist vs a dopamine reuptake inhibitor (DRI), either a monoamine oxidase type B (MAO-B) inhibitor or a catechol-O-methyltransferase (COMT) inhibitor, to levodopa therapy for the treatment of patients with motor complications of PD. DESIGN, SETTING, AND PARTICIPANTS This pragmatic semifactorial (2 × 1) randomized clinical trial recruited from 64 neurology and geriatric clinics (62 in the United Kingdom, 1 in the Czech Republic, and 1 in Russia) between February 23, 2001, and December 15, 2009. A total of 500 patients with idiopathic PD who developed uncontrolled motor complications and did not have dementia were randomly assigned on a 1:1:1 basis using a computerized minimization program. Data were analyzed between 2017 and 2020. INTERVENTIONS Open-label dopamine agonist, MAO-B inhibitor, or COMT inhibitor. MAIN OUTCOMES AND MEASURES Primary outcomes were scores on the 39-item Parkinson's Disease Questionnaire (PDQ-39) mobility domain and cost-effectiveness. Outcomes were assessed before study entry, at 6 and 12 months after randomization, and annually thereafter. Repeated-measures and log rank analyses were used in an intention-to-treat approach. RESULTS Among 500 participants, the mean (SD) age was 73.0 (8.2) years; 314 participants (62.8%) were men. Over a median of 4.5 years (range, 0-13.3 years) of follow-up, the participants in the dopamine agonist group had a mean PDQ-39 mobility score that was 2.4 points (95% CI, −1.3 to 6.0 points) better than that of the combined MAO-B and COMT groups; however, this difference was not significant (P=.20). With regard to DRIs, participants in the MAO-B group had mean PDQ-39 mobility scores that were 4.2 points (95% CI, 0.4-7.9 points; P=.03) better than those of the COMT group and EuroQol 5-dimension 3-level (EQ-5D-3L) utility scores that were 0.05 points (95% CI, 0.003-0.09 points; P=.04) better than the COMT group. Nonsignificant improvements were found in the PDQ-39 summary index (mean difference, 2.2 points; 95% CI, −0.2 to 4.5 points; P=.07) along with nonsignificant reductions in dementia (rate ratio [RR], 0.70; 95% CI, 0.47-1.03; P = .07) and mortality (RR, 0.76; 95% CI, 0.56-1.03; P=.07). When dopamine agonists were compared with MAO-B inhibitors only, the outcomes were similar. CONCLUSIONS AND RELEVANCE In this study, patient-rated quality of life was inferior when COMT inhibitors were used as adjuvant treatment compared with MAO-B inhibitors or dopamine agonists among people with PD who experienced motor complications that were uncontrolled by levodopa therapy. The MAO-B inhibitors produced equivalent disease control, suggesting that these agents may be underused as adjuvant therapy.

Research paper thumbnail of Leucocyte antigens in baboons — A preliminary to tissue typing for organ grafting

Transplantation Proceedings

Research paper thumbnail of Effect of agitation on the quality of platelet concentrates

Vox sanguinis, 1994

Platelet concentrates (PCs) were stored for 4 days at 22 degrees C in 400 ml second-generation (P... more Platelet concentrates (PCs) were stored for 4 days at 22 degrees C in 400 ml second-generation (PL1240) platelet packs with either constant agitation, manual mixing once every 24 h or without agitation at any time. After 4 days storage, in vivo recovery, survival and biodistribution were determined following indium-111 labelling of platelets and infusion into autologous volunteers. In vitro assays of platelet function and biochemistry were likewise carried out after 4 days storage. The PCs stored without agitation had significantly lower in vivo recoveries, pH and aggregation responses to ionophore A23187 and a combination of collagen and epinephrine and significantly higher beta-thromboglobulin and indium-111 release than the agitated PCs. The manually mixed PCs were not significantly different from the constantly agitated PCs. PCs mixed simply once every 24 h remained viable with active oxidative phosphorylation and a pH above 6.74 in all but 1 case indicating that PCs stored at 2...

Research paper thumbnail of Indium (111In)-labelled human platelets: optimal method

Clinical science (London, England : 1979), 1980

1. A detailed laboratory method is described for the labelling of human platelets with [111In]ind... more 1. A detailed laboratory method is described for the labelling of human platelets with [111In]indium oxine. The 45 min method is simple, requires on 26 ml of blood and is suitable for routine clinical use. 2. After the labelling and resuspension of the platelets in plasma, aggregation responses to both adenosine diphosphate and collagen were similar to those of normal platelet-rich plasma. Less than 5% of the [111In]indium oxine was released by secretory function of platelets. 3. Labelling efficiencies of 90.1 +/- 4.29% (n = 28) were achieved in 60 s by normal concentrations of plasma-free platelet suspensions. 4. Platelet survival in vivo in healthy volunteer subjects follows a linear function with a survival time of 8.44 +/- 0.18 days.

Research paper thumbnail of Radiolabeled leukocytes in prosthetic graft infection

Research paper thumbnail of Platelet inhibitory drugs: an in vivo method of evaluation in patients

Thrombosis and haemostasis, Jan 27, 1982

The measurement of platelet deposition in human thrombi is essential for the evaluation of platel... more The measurement of platelet deposition in human thrombi is essential for the evaluation of platelet-inhibitory drugs and prosthetic materials for use in patients. The rate of 111Indium-labelled platelet accumulation on Dacron arterial grafts was measured in 27 patients randomised to take either aspirin and dipyridamole (ASA + DPM) or placebo. Autologous platelets were labelled and re-injected seven days following surgery and the graft thrombogenicity index calculated as the daily rise in the ratio of emissions from the graft over a reference site. The mean (+/- SD) thrombogenicity index in 12 patients undergoing femoro-popliteal bypass was 0.25 +/- 0.09 on placebo and 0.16 +/- 0.07 on ASA + DPM started pre-operatively (p less than 0.05). Post-operative ASA + DPM therapy started two days following platelet labelling in 15 patients with aorto-femoral grafts also significantly reduce thrombogenicity to 0.12 +/- 0.05 compared with 0.25 +/- 0.08 on placebo (p less than 0.01). In the latt...

Research paper thumbnail of Indium-111 labeled platelets in monitoring pancreatic transplants in humans

Transplantation proceedings, 1984

Research paper thumbnail of Indium-111 tropolone versus oxine

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1983

Research paper thumbnail of Indium-111-labeled platelets as a diagnostic aid in posttransplant monitoring of renal allografts in humans

Transplantation proceedings, 1984

Research paper thumbnail of Indium-labeled platelet uptake in rejecting renal transplants

Surgery, gynecology & obstetrics, 1983

The uptake of 111In autologous platelets in transplanted kidneys was measured in 16 patients shor... more The uptake of 111In autologous platelets in transplanted kidneys was measured in 16 patients shortly after operation. Each patient was then observed for two years. When transplant radioactivity had increased, despite treatment for acute rejection, the kidney was ultimately lost because of rejection.

Research paper thumbnail of Dacron arterial grafts: the influence of porosity, velour, and maturity on thrombogenicity

Surgery, 1982

It has been claimed that the neointimal healing of Dacron arterial prostheses can be enhanced by ... more It has been claimed that the neointimal healing of Dacron arterial prostheses can be enhanced by increasing porosity and including both an internal and an external velour layer. To test this, 24 patients received at random either woven (USCI, DeBakey, C. R. Bard, Inc.) or more porous, double-velour, knitted (Microvel, Meadox Medicals, Inc.) Dacron aortobifemoral prostheses. Graft thrombogenicity was measured using autogenous 111In-labeled platelets shortly following surgery and 6 to 9 months later. The thrombogenicity index was defined as the mean daily rise in the ratio of emissions over the graft to emissions over a reference area (aortic arch) and is a measure of platelet deposition. At early study the mean (+/- SE) thrombogenicity index was similar in woven and knitted graft patients at 0.19 +/- 0.4 and 0.14 +/- 0.2, respectively. In both groups it was lower (P less than 0.05) 6 to 9 months later at 0.06 +/- 0.2 (woven( and 0.08 +/- 0.1 (knitted), with again no difference betwee...

Research paper thumbnail of Tubular damage or rejection: bedside method for differential diagnosis in patients on cyclosporin

Research paper thumbnail of The production of immunosuppressive antisera

Proceedings of the European Dialysis and Transplant Association. European Dialysis and Transplant Association, 1972

Research paper thumbnail of Evaluation of three methods of platelet labelling

Nuclear medicine communications, 1986

The study of the kinetics of labelled platelets makes sense only when the platelets preserve thei... more The study of the kinetics of labelled platelets makes sense only when the platelets preserve their viability after separation and labelling. The separation and labelling procedures described in the manual of two producers of 111In-oxinate (Amersham, Mallinckrodt) have been evaluated by in vitro aggregation tests. The method of Mallinckrodt diminished the aggregation capacities of the thrombocytes. The labelled platelets with normal in vitro aggregation response (Amersham) were tested in vivo in 11 patients who underwent peripheral bypass surgery. The platelet half-life and the platelet accumulation on bypass grafts were checked one week post-operatively. Because of the poor in vivo response of both methods (exponential half-life curve and bad graft visualization), a third method was optimized in our laboratory with good in vitro and in vivo results in 12 patients.

Research paper thumbnail of Proceedings: 125I-labelled autologous fibrinogen for deep vein thrombosis detection and metabolic studies

The British journal of surgery, 1976

Research paper thumbnail of Protein losses during sterilizing by filtration

Laboratory practice, 1975

Research paper thumbnail of Vessel for the rapid extraction of plasma proteins

Laboratory practice, 1975

Research paper thumbnail of Dopamine agonist therapy in early Parkinson's disease

Reviews, 1996

ABSTRACT This 'umbrella' meta-analysis assesses dopamine agonists as a drug class... more ABSTRACT This 'umbrella' meta-analysis assesses dopamine agonists as a drug class in early Parkinson's disease. Twenty-nine eligible trials, involving 5247 participants, were identified. It confirms reports from individual trials that motor complications are reduced with dopamine agonists compared to levodopa, but also demonstrates that other important side-effects are increased and symptom control is poorer with agonists. Unfortunately, the balance of risks and benefits remains unclear highlighting the need for further studies assessing patient-rated overall quality of life and economic measures as their primary outcomes.

Research paper thumbnail of Improvements in long tendon support with pumpable resin

Long tendon support systems provide several challenges when used as part of the secondary or prim... more Long tendon support systems provide several challenges when used as part of the secondary or primary support cycle. A two-component pumpable resin, Carbothix, has been in development for use with self-drilling rock bolts. Many of the attributes of this new resin system make it ideal for grouting long tendon support systems. While neat Portland cement grouts or polyester resin capsules have been used with long tendon support systems for many years, two-component pumpable resin systems overcome many of the shortcomings in these systems. The two-component systems dramatically improve the set-time to enable mining face advance with fewer delays, enable longer pumping distances, improve quality control, and enhance load transfer mechanisms. This paper describes the key benefits associated with a new pumpable resin and details the Coal Services Health/Workcover atmospheric testing results and cable load testing completed to date. It also details the results of the Australian mine site trials and the introduction of these systems into production use.

Research paper thumbnail of A method to demonstrate inadequate blood component mixing

Nuclear Medicine Communications, 1995

Research paper thumbnail of Long-term Effectiveness of Adjuvant Treatment With Catechol-O-Methyltransferase or Monoamine Oxidase B Inhibitors Compared With Dopamine Agonists Among Patients With Parkinson Disease Uncontrolled by Levodopa Therapy

JAMA Neurology

IMPORTANCE Many people with Parkinson disease (PD) develop motor complications that are uncontrol... more IMPORTANCE Many people with Parkinson disease (PD) develop motor complications that are uncontrolled by levodopa dose adjustment. Among these patients, it is uncertain which drug class is more effective as adjuvant therapy. OBJECTIVE To compare the long-term effects on patient-rated quality of life of adding a dopamine agonist vs a dopamine reuptake inhibitor (DRI), either a monoamine oxidase type B (MAO-B) inhibitor or a catechol-O-methyltransferase (COMT) inhibitor, to levodopa therapy for the treatment of patients with motor complications of PD. DESIGN, SETTING, AND PARTICIPANTS This pragmatic semifactorial (2 × 1) randomized clinical trial recruited from 64 neurology and geriatric clinics (62 in the United Kingdom, 1 in the Czech Republic, and 1 in Russia) between February 23, 2001, and December 15, 2009. A total of 500 patients with idiopathic PD who developed uncontrolled motor complications and did not have dementia were randomly assigned on a 1:1:1 basis using a computerized minimization program. Data were analyzed between 2017 and 2020. INTERVENTIONS Open-label dopamine agonist, MAO-B inhibitor, or COMT inhibitor. MAIN OUTCOMES AND MEASURES Primary outcomes were scores on the 39-item Parkinson's Disease Questionnaire (PDQ-39) mobility domain and cost-effectiveness. Outcomes were assessed before study entry, at 6 and 12 months after randomization, and annually thereafter. Repeated-measures and log rank analyses were used in an intention-to-treat approach. RESULTS Among 500 participants, the mean (SD) age was 73.0 (8.2) years; 314 participants (62.8%) were men. Over a median of 4.5 years (range, 0-13.3 years) of follow-up, the participants in the dopamine agonist group had a mean PDQ-39 mobility score that was 2.4 points (95% CI, −1.3 to 6.0 points) better than that of the combined MAO-B and COMT groups; however, this difference was not significant (P=.20). With regard to DRIs, participants in the MAO-B group had mean PDQ-39 mobility scores that were 4.2 points (95% CI, 0.4-7.9 points; P=.03) better than those of the COMT group and EuroQol 5-dimension 3-level (EQ-5D-3L) utility scores that were 0.05 points (95% CI, 0.003-0.09 points; P=.04) better than the COMT group. Nonsignificant improvements were found in the PDQ-39 summary index (mean difference, 2.2 points; 95% CI, −0.2 to 4.5 points; P=.07) along with nonsignificant reductions in dementia (rate ratio [RR], 0.70; 95% CI, 0.47-1.03; P = .07) and mortality (RR, 0.76; 95% CI, 0.56-1.03; P=.07). When dopamine agonists were compared with MAO-B inhibitors only, the outcomes were similar. CONCLUSIONS AND RELEVANCE In this study, patient-rated quality of life was inferior when COMT inhibitors were used as adjuvant treatment compared with MAO-B inhibitors or dopamine agonists among people with PD who experienced motor complications that were uncontrolled by levodopa therapy. The MAO-B inhibitors produced equivalent disease control, suggesting that these agents may be underused as adjuvant therapy.

Research paper thumbnail of Leucocyte antigens in baboons — A preliminary to tissue typing for organ grafting

Transplantation Proceedings

Research paper thumbnail of Effect of agitation on the quality of platelet concentrates

Vox sanguinis, 1994

Platelet concentrates (PCs) were stored for 4 days at 22 degrees C in 400 ml second-generation (P... more Platelet concentrates (PCs) were stored for 4 days at 22 degrees C in 400 ml second-generation (PL1240) platelet packs with either constant agitation, manual mixing once every 24 h or without agitation at any time. After 4 days storage, in vivo recovery, survival and biodistribution were determined following indium-111 labelling of platelets and infusion into autologous volunteers. In vitro assays of platelet function and biochemistry were likewise carried out after 4 days storage. The PCs stored without agitation had significantly lower in vivo recoveries, pH and aggregation responses to ionophore A23187 and a combination of collagen and epinephrine and significantly higher beta-thromboglobulin and indium-111 release than the agitated PCs. The manually mixed PCs were not significantly different from the constantly agitated PCs. PCs mixed simply once every 24 h remained viable with active oxidative phosphorylation and a pH above 6.74 in all but 1 case indicating that PCs stored at 2...

Research paper thumbnail of Indium (111In)-labelled human platelets: optimal method

Clinical science (London, England : 1979), 1980

1. A detailed laboratory method is described for the labelling of human platelets with [111In]ind... more 1. A detailed laboratory method is described for the labelling of human platelets with [111In]indium oxine. The 45 min method is simple, requires on 26 ml of blood and is suitable for routine clinical use. 2. After the labelling and resuspension of the platelets in plasma, aggregation responses to both adenosine diphosphate and collagen were similar to those of normal platelet-rich plasma. Less than 5% of the [111In]indium oxine was released by secretory function of platelets. 3. Labelling efficiencies of 90.1 +/- 4.29% (n = 28) were achieved in 60 s by normal concentrations of plasma-free platelet suspensions. 4. Platelet survival in vivo in healthy volunteer subjects follows a linear function with a survival time of 8.44 +/- 0.18 days.

Research paper thumbnail of Radiolabeled leukocytes in prosthetic graft infection

Research paper thumbnail of Platelet inhibitory drugs: an in vivo method of evaluation in patients

Thrombosis and haemostasis, Jan 27, 1982

The measurement of platelet deposition in human thrombi is essential for the evaluation of platel... more The measurement of platelet deposition in human thrombi is essential for the evaluation of platelet-inhibitory drugs and prosthetic materials for use in patients. The rate of 111Indium-labelled platelet accumulation on Dacron arterial grafts was measured in 27 patients randomised to take either aspirin and dipyridamole (ASA + DPM) or placebo. Autologous platelets were labelled and re-injected seven days following surgery and the graft thrombogenicity index calculated as the daily rise in the ratio of emissions from the graft over a reference site. The mean (+/- SD) thrombogenicity index in 12 patients undergoing femoro-popliteal bypass was 0.25 +/- 0.09 on placebo and 0.16 +/- 0.07 on ASA + DPM started pre-operatively (p less than 0.05). Post-operative ASA + DPM therapy started two days following platelet labelling in 15 patients with aorto-femoral grafts also significantly reduce thrombogenicity to 0.12 +/- 0.05 compared with 0.25 +/- 0.08 on placebo (p less than 0.01). In the latt...

Research paper thumbnail of Indium-111 labeled platelets in monitoring pancreatic transplants in humans

Transplantation proceedings, 1984

Research paper thumbnail of Indium-111 tropolone versus oxine

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1983

Research paper thumbnail of Indium-111-labeled platelets as a diagnostic aid in posttransplant monitoring of renal allografts in humans

Transplantation proceedings, 1984

Research paper thumbnail of Indium-labeled platelet uptake in rejecting renal transplants

Surgery, gynecology & obstetrics, 1983

The uptake of 111In autologous platelets in transplanted kidneys was measured in 16 patients shor... more The uptake of 111In autologous platelets in transplanted kidneys was measured in 16 patients shortly after operation. Each patient was then observed for two years. When transplant radioactivity had increased, despite treatment for acute rejection, the kidney was ultimately lost because of rejection.

Research paper thumbnail of Dacron arterial grafts: the influence of porosity, velour, and maturity on thrombogenicity

Surgery, 1982

It has been claimed that the neointimal healing of Dacron arterial prostheses can be enhanced by ... more It has been claimed that the neointimal healing of Dacron arterial prostheses can be enhanced by increasing porosity and including both an internal and an external velour layer. To test this, 24 patients received at random either woven (USCI, DeBakey, C. R. Bard, Inc.) or more porous, double-velour, knitted (Microvel, Meadox Medicals, Inc.) Dacron aortobifemoral prostheses. Graft thrombogenicity was measured using autogenous 111In-labeled platelets shortly following surgery and 6 to 9 months later. The thrombogenicity index was defined as the mean daily rise in the ratio of emissions over the graft to emissions over a reference area (aortic arch) and is a measure of platelet deposition. At early study the mean (+/- SE) thrombogenicity index was similar in woven and knitted graft patients at 0.19 +/- 0.4 and 0.14 +/- 0.2, respectively. In both groups it was lower (P less than 0.05) 6 to 9 months later at 0.06 +/- 0.2 (woven( and 0.08 +/- 0.1 (knitted), with again no difference betwee...

Research paper thumbnail of Tubular damage or rejection: bedside method for differential diagnosis in patients on cyclosporin

Research paper thumbnail of The production of immunosuppressive antisera

Proceedings of the European Dialysis and Transplant Association. European Dialysis and Transplant Association, 1972

Research paper thumbnail of Evaluation of three methods of platelet labelling

Nuclear medicine communications, 1986

The study of the kinetics of labelled platelets makes sense only when the platelets preserve thei... more The study of the kinetics of labelled platelets makes sense only when the platelets preserve their viability after separation and labelling. The separation and labelling procedures described in the manual of two producers of 111In-oxinate (Amersham, Mallinckrodt) have been evaluated by in vitro aggregation tests. The method of Mallinckrodt diminished the aggregation capacities of the thrombocytes. The labelled platelets with normal in vitro aggregation response (Amersham) were tested in vivo in 11 patients who underwent peripheral bypass surgery. The platelet half-life and the platelet accumulation on bypass grafts were checked one week post-operatively. Because of the poor in vivo response of both methods (exponential half-life curve and bad graft visualization), a third method was optimized in our laboratory with good in vitro and in vivo results in 12 patients.

Research paper thumbnail of Proceedings: 125I-labelled autologous fibrinogen for deep vein thrombosis detection and metabolic studies

The British journal of surgery, 1976

Research paper thumbnail of Protein losses during sterilizing by filtration

Laboratory practice, 1975

Research paper thumbnail of Vessel for the rapid extraction of plasma proteins

Laboratory practice, 1975

Research paper thumbnail of Dopamine agonist therapy in early Parkinson's disease

Reviews, 1996

ABSTRACT This 'umbrella' meta-analysis assesses dopamine agonists as a drug class... more ABSTRACT This 'umbrella' meta-analysis assesses dopamine agonists as a drug class in early Parkinson's disease. Twenty-nine eligible trials, involving 5247 participants, were identified. It confirms reports from individual trials that motor complications are reduced with dopamine agonists compared to levodopa, but also demonstrates that other important side-effects are increased and symptom control is poorer with agonists. Unfortunately, the balance of risks and benefits remains unclear highlighting the need for further studies assessing patient-rated overall quality of life and economic measures as their primary outcomes.