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Martin BJ, Finlay JA, Sterling K, Ward M, Lifsey D, Mercante D, Jainto JM, Martin L, Rayford W. Early detection of prostate cancer in African-American men through use of multiple biomarkers: human kallikrein 2 (hK2), prostate-specific antigen (PSA), and free PSA (fPSA). Prostate Cancer Prostatic Dis 2004; 7:132-7. [PMID: 15007379 DOI: 10.1038/sj.pcan.4500706] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recent studies have reported enhanced prostate cancer detection in Caucasians with serum human glandular kallikrein 2 (hK2) in combination with total- (tPSA) and free-prostate-specific antigen (fPSA). The purpose of this study is to validate these findings in an African-American patient cohort. A total of 137 African-American men were found by routine screening to have tPSA levels above 2.5 ng/ml or an abnormal digital rectal examination. Sera were drawn prior to biopsy of the prostate and Hybritech PSA, FPSA and hK2 (for research use only, not for use in diagnostic procedures) concentrations were determined on Beckman Coulter's Access immunoanalyzer. These independent variables and the ratios of percent fPSA (%fPSA), hK2/tPSA, hK2/fPSA, and hK2*tPSA/fPSA were compared between cancer and non-cancer groups. In all, 49 of 137 men had prostate cancer. hK2 and its calculated ratios outperformed tPSA on receiver operator characteristic (ROC) analysis, but %fPSA had statistically the highest area under the curve (AUC) at 0.801. When restricting the analysis to only the tPSA range of 4.0-10 ng/ml, hK2/fPSA yielded the highest AUC (0.721). The ratio of hK2/fPSA was also found to increase the positive predictive value (PPV) of the %fPSA ranges less than 10 and 10-25%. %fPSA offered the best performance and highest specificity in prostate cancer detection in African-American males over the entire range of tPSA. hK2/fPSA may offer modest improvement in the tPSA range of 4.0-10 ng/ml. Furthermore, hK2/fPSA can enhance the PPV of low %fPSA values. Therefore, the use of multiple biomarkers may ultimately increase the specificity of prostate cancer screening in African-American men.
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Martin BJ, Cheli C, Davis R, Ward M, Kokatnur M, Mercante D, Lifsey D, Rayford W. cPSA and fPSA elimination in African-American men. Prostate Cancer Prostatic Dis 2004; 6:163-8. [PMID: 12806377 DOI: 10.1038/sj.pcan.4500649] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In all, 22 African-American males undergoing radical prostatectomy for prostate adenocarcinoma had serum drawn for tPSA, cPSA, and total protein concentrations prior to, during, and after operation to determine the respective elimination rates. African-American cPSA was found to fit best a simple first-order exponential elimination kinetic, with a half-life of 44.6 h. fPSA followed a two-compartment elimination with an alpha-phase elimination of 0.50 h and a beta-phase half-life of 4.2 h. Our results suggest higher rates of elimination for both cPSA and fPSA in an African-American male population with respect to Caucasians and may account for differences in PSA values between races.
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Martin BJ, Yip B, Hearty M, Marletta S, Hill R. Outcome, functional recovery and unmet needs following acute stroke. Experience of patient follow up at 6 to 9 months in a newly established stroke service. Scott Med J 2002; 47:136-7. [PMID: 12616970 DOI: 10.1177/003693300204700605] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To assess outcome at six months post stroke and the unmet needs and adherence to the secondary prevention advice among survivors living at home. SETTING Stroke Rehabilitation Unit (SRU), Hairmyres Hospital and patients homes. SUBJECTS Survivors living at home who had been managed in the SRU. RESULTS Of 572 consecutive patients with confirmed acute stroke, 301 were managed in the SRU and 179 of these were reviewed at home between 6 and 9 months post acute stroke incident. One hundred and thirty seven (76%) survivors at home were living with a carer. Sixty-eight (38%) had had no personal contact with their General Practitioner since discharge from hospital, although 83 (46%) had attended or were attending day hospital. Thirty-two individuals (18%) had resumed smoking. One hundred and forty nine survivors (83%) still required assistance with daily living tasks. One hundred and fifteen patients (64%) required medication advice. One hundred and forty one (79%) had health concerns. Eight subjects had returned to paid employment. Issues raised by survivors included a feeling of being abandoned by the healthcare system, poor access to professional psychological support and a fear of further stroke. CONCLUSION There is a need for continuing patient education, improved support for stroke survivors and more active involvement of Primary Care Services in the care of stroke patients following hospital discharge.
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Arend O, Remky A, Plange N, Martin BJ, Harris A. Capillary density and retinal diameter measurements and their impact on altered retinal circulation in glaucoma: a digital fluorescein angiographic study. Br J Ophthalmol 2002; 86:429-33. [PMID: 11914213 PMCID: PMC1771098 DOI: 10.1136/bjo.86.4.429] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AIM Normal pressure glaucoma (NPG) patients exhibit prolonged retinal arteriovenous passage times in fluorescein angiography and colour Doppler imaging suggests increased resistance downstream from the central retinal and posterior ciliary arteries. The aim of the study was to elucidate the morphological source of decreased perfusion and increased resistance of the ocular circulation in NPG. METHODS Retinal arteriovenous passage time (AVP) and peripapillary arterial and venous diameters were measured in digital scanning laser fluorescein angiograms. For estimation of retinal capillary density the area of the foveal avascular zone (FAZ) and the perifoveal intercapillary area (PIA) was quantified. 36 patients with NPG (mean age 57 (SD 13) years) and 21 healthy subjects (mean age 51 (13) years) were enrolled in the comparative study. RESULTS In NPG patients the AVP (2.55 (1.1) seconds) was significantly prolonged (p<0.001) when compared with healthy subject data (AVP: 1.70 (0.39) seconds). No differences for arterial or venous diameter, FAZ, and PIA were observed in NPG patients compared with healthy subjects. FAZ, PIA, arterial and venous diameter were not correlated with visual field indices (except venous diameter with PSD, r=0.35 (p<0.05)) or cup to disc ratios. AVP was significantly correlated (p<0.05) with the size of the optic nerve head (r=-0.28), visual field indices (MD: r=-0.3; PSD: r=0.3; CPSD: r=0.3), and contrast sensitivity (r=-0.34). CONCLUSION AVP times are significantly prolonged in NPG. The slowing of the retinal transit does not result from capillary dropout, or changes of peripapillary arterial or venous diameters with increased vascular resistance.
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Barber M, Braid V, Mitchell SL, Martin BJ, Grant SJ, Granat M, Stott DJ. Electrical stimulation of quadriceps during rehabilitation following proximal femoral fracture. Int J Rehabil Res 2002; 25:61-3. [PMID: 11953717 DOI: 10.1097/00004356-200203000-00009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Devine SM, Peter S, Martin BJ, Barry F, McIntosh KR. Mesenchymal stem cells: stealth and suppression. Cancer J 2001; 7 Suppl 2:S76-82. [PMID: 11777268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Human post-natal bone marrow contains mesenchymal stem cells (MSCs), which are capable of giving rise to multiple mesenchymal cell lineages. Large quantities of human MSCs can be readily obtained following a simple bone marrow aspiration procedure and subsequent expansion over a million-fold in culture. This extensive capacity for clinical scale expansion in vitro has facilitated the development of preclinical models as well as clinical studies designed to assess the safety, feasibility, and efficacy of transplanting allogeneic MSCs for a variety of indications. This review focuses on the rationale for performing clinical studies of MSC transplantation and will discuss the potential role that MSCs may have in the field of hematopoietic stem cell transplantation as well as for the repair or regeneration of bone, cartilage, and cardiac tissues.
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Mitchell SL, Stott DJ, Martin BJ, Grant SJ. Randomized controlled trial of quadriceps training after proximal femoral fracture. Clin Rehabil 2001; 15:282-90. [PMID: 11386398 DOI: 10.1191/026921501676849095] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE To determine whether systematic progressive high-intensity quadriceps training increases leg extensor power and reduces disability in patients rehabilitating after proximal femoral fracture. DESIGN Open parallel group randomized controlled trial comparing the addition of six weeks quadriceps training (40 patients) with standard physiotherapy alone (40 patients). The training group exercised twice weekly, with six sets of 12 repetitions of knee extension (both legs), progressing up to 80% of their one-repetition maximum. SETTING Orthogeriatric unit, and community follow-up. SUBJECTS Eighty patients rehabilitating after proximal femoral fracture. MAIN OUTCOME MEASURES Measurements of leg extensor power (Nottingham Power Rig), functional mobility (elderly mobility score), disability (Barthel Index) and quality of life (Nottingham Health Profile) were made at baseline, after six weeks (at the end of the intervention) and at 16 weeks. RESULTS Leg extensor power increased significantly in the quadriceps training group (fractured leg mean improvement at six weeks 157% (standard error 16), nonfractured leg 80% (12)) compared with the control group (63% (11) and 26% (8) respectively, unpaired Student's t-test p = 0.007 and p = 0.01 for between-group comparisons). Significant benefits were maintained at 16 weeks. Quadriceps training resulted in a greater increase in elderly mobility scale score compared with standard rehabilitation (between-group difference of 2.5 (95% CI 1.1,3.8) at week 6 and 1.9 (0.4,3.4) at week 16). Barthel score increased significantly from week 0 to 6 in the quadriceps training group compared with controls (Mann-Whitney U-test p = 0.05). Patients in the quadriceps training group scored significantly better in the energy subscore of the Nottingham Health Profile at the end of follow-up (Mann-Whitney U-test p = 0.0185). CONCLUSIONS Progressive high-intensity quadriceps training in elderly proximal femoral fracture patients increased leg extensor power and reduced disability. This was accompanied by an increase in energy as measured by the Nottingham Health Profile. This intervention may provide a simple practical way of improving outcome in these patients.
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Spilg EG, Martin BJ, Mitchell SL, Aitchison TC. A comparison of mobility assessments in a geriatric day hospital. Clin Rehabil 2001; 15:296-300. [PMID: 11386400 DOI: 10.1191/026921501675281708] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE To assess the sensitivity of the Elderly Mobility Scale (EMS) to detect improvements in mobility after physiotherapy in comparison with the Barthel Index (BI) and Functional Ambulation Category (FAC) in routine clinical day hospital practice. SUBJECTS Eighty-three patients who completed a course of physiotherapy were studied. METHODS Each was assessed by an independent physiotherapist before and after a programme of physiotherapy, using the EMS, BI and FAC. RESULTS The mean age was 79 years (SD 7.7). Fifty-three out of 83 (64%) patients were female and 92% were community dwelling. The median number of physiotherapy sessions undergone by each patient was 9 (range 3-51). All three scales detected an improvement in mobility with physiotherapy (p < 0.001). However, using the EMS, 68 out of 82 (83%) patients had a detectable improvement in mobility compared with only 34 out of 80 (42%) using the BI and 28 out of 81 (35%) using the FAC. Using a matched-pairs comparison, the EMS was significantly more likely to detect an improvement in mobility following physiotherapy within the study group than the BI (p < 0.001) or the FAC (p < 0.001). CONCLUSION Although all three scales detected improvements in mobility, the EMS detected mobility improvements in a significantly greater number of patients.
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Ciulla TA, Harris A, Martin BJ. Ocular perfusion and age-related macular degeneration. ACTA OPHTHALMOLOGICA SCANDINAVICA 2001; 79:108-15. [PMID: 11284745 DOI: 10.1034/j.1600-0420.2001.079002108.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
PURPOSE To review the role of ocular perfusion in the pathophysiology of age-related macular degeneration (AMD), the leading cause of irreversible blindness in the industrialized world. METHODS Medline search of the literature published in English or with English abstracts from 1966 to 2000 was performed using various combinations of relevant key words. RESULTS Vascular defects have been identified in both nonexudative and exudative AMD patients using fluorescein angiographic methods, laser Doppler flowmetry, indocyanine green angiography, and color Doppler imaging. CONCLUSION Although these studies lend some support to the vascular pathogenesis of AMD, it is not possible to determine if the choroidal perfusion abnormalities play a causative role in nonexudative AMD, if they are simply an association with another primary alteration, such as a primary RPE defect or a genetic defect at the photoreceptor level, or if they are more strongly associated with one particular form of this heterogeneous disease. Further study is warranted.
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Harris-Yitzhak M, Harris A, Ben-Refael Z, Zarfati D, Garzozi HJ, Martin BJ. Estrogen-replacement therapy: effects on retrobulbar hemodynamics. Am J Ophthalmol 2000; 129:623-8. [PMID: 10844054 DOI: 10.1016/s0002-9394(99)00468-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
PURPOSE Estrogen-replacement therapy causes vasodilation and increased blood flow in major peripheral arteries. We examined the role that estrogen may play in enhancing perfusion within the watersheds of several major and minor retrobulbar arteries. METHODS Postmenopausal women receiving estrogen-replacement therapy (n = 16) were compared with both age-matched women not receiving estrogen (n = 16) and with young women (n = 20). Studies involved color Doppler imaging analysis of flow velocities measured in the ophthalmic, central retinal, and nasal and temporal posterior ciliary arteries. RESULTS In the ophthalmic artery, young women and postmenopausal women receiving estrogen exhibited reduced resistance indexes as compared with postmenopausal women not receiving estrogen (each P <. 001). In contrast, flow velocities in the central retinal artery were similar among the three groups of women. In the posterior ciliary arteries, a different pattern emerged: young women, as compared with either group of postmenopausal women, showed greater peak systolic and end-diastolic velocities at similar resistance index (each P <.05). CONCLUSIONS Estrogen-replacement therapy in postmenopausal women apparently helps reduce vascular resistance distal to the ophthalmic artery to levels matching those of young women. However, estrogen replacement has little impact on flow velocities in the posterior ciliary arteries. In those vessels, aging per se may reduce perfusion, potentially contributing to the age-dependent risk of major eye diseases, such as glaucoma and age-related macular degeneration.
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Gerard MJ, Armstrong TJ, Franzblau A, Martin BJ, Rempel DM. The effects of keyswitch stiffness on typing force, finger electromyography, and subjective discomfort. AMERICAN INDUSTRIAL HYGIENE ASSOCIATION JOURNAL 1999; 60:762-9. [PMID: 10635542 DOI: 10.1080/00028899908984499] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The effects of keyswitch stiffness and key action on typing force, electromyography (EMG), and subjective preference were examined. Each subject's own keyboard (with an audible key click and key activation force of 0.72 N) and three keyboards with no key click that were identical in design but had different key activation forces (0.28 N, 0.56 N, and 0.83 N) were used. Subjects (24 female transcriptionists) typed on each keyboard for 15 min while typing force and left hand surface EMG of the finger flexor and extensor muscles were monitored. Subjects then used one of the keyboards at their workstations for 7 workdays and were monitored again. This procedure was repeated for all four keyboards. Typing force and finger flexor and extensor EMG activity were highest for the 0.83 N keyboard. Lowest EMG values were for the 0.28 N and the 0.72 N audible key click keyboards. Baseline (10th percentile) and median (50th percentile) extensor EMG values were significantly higher than flexor EMG values. Peak (90th percentile) EMG values were comparable for flexors and extensors. Mean subjective discomfort was significantly higher for the 0.83 N keyboard at the fingers (36% higher), lower arm (40% higher), and overall (39% higher). Seventeen of 24 subjects preferred the 0.72 N keyboard, 4 the 0.28 N keyboard, and 3 preferred the 0.56 N keyboard. Results suggest that increasing make force causes typing force and EMG to increase but that the ratio of 90th centile typing force to make force decreases as make force increases. Subjective discomfort was significantly higher for the keyboard with 0.83 N make force. Buckling spring keyboards have better feedback characteristics, which may be responsible for a decrease in the amount of typing force and EMG produced.
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Arend O, Harris A, Martin BJ, Remky A. Scanning laser ophthalmoscopy-based evaluation of epipapillary velocities: method and physiologic variability. Surv Ophthalmol 1999; 44 Suppl 1:S3-9. [PMID: 10548113 DOI: 10.1016/s0039-6257(99)00088-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
PURPOSE Scanning laser ophthalmoscopy is capable of producing high-resolution fluorescein angiograms. Measurements of capillary blood velocities in the fovea are well established. In this study, we used an identical technique to measure particle velocities in the superficial layers of the optic nerve head. We compared these data with simultaneous velocity measurements in the retinal and macular vasculature. METHODS Fluorescein angiograms were performed in 30 subjects (12 men, 18 women; mean age, 26 years; standard deviation [SD], 3 years). Off-line, the velocities of hypofluorescent particles through the microvasculature of epipapillary and macular vessels were measured by image-processing techniques. We also assessed the arteriovenous passage (AVP) time of the fluorescein dye front. RESULTS Epipapillary blood velocities ranged from 2.7 to 6.5 mm/sec (mean, 4.0 mm/sec; SD, 0.99 mm/sec) and differed significantly from macular capillary blood velocities (MCBVs), which ranged from 1.67 to 3.31 mm/sec (mean, 2.53 mm/sec; SD, 0.34 mm/sec). The AVP time in all subjects was 1.74 +/- 0.5 sec (mean +/- SD) and correlated with the MCBV (P < 0.05, r = -0.46). Epipapillary blood velocities showed no correlation with either AVP time or MCBV. CONCLUSIONS The scanning laser methodology, adapted to objectively assess velocities in the epipapillary vasculature, shows that these measurements are neither correlated with velocities in the perifoveal network, nor inversely correlated with overall retinal transit time. Epipapillary blood velocities were found to be substantially higher than those measured in macular capillaries. This result might be explained by the different anatomy of epipapillary vessels compared with macular capillaries.
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Chung HS, Harris A, Halter PJ, Kagemann L, Roff EJ, Garzozi HJ, Hosking SL, Martin BJ. Regional differences in retinal vascular reactivity. Invest Ophthalmol Vis Sci 1999; 40:2448-53. [PMID: 10476818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023] Open
Abstract
PURPOSE Although glaucomatous visual field defects are more common in the superior field than in the inferior field, microaneurysms are more frequent in the superior than in the inferior retina in diabetic retinopathy. The authors hypothesized that differences in vascular hemodynamics in the two areas might contribute to these phenomena. METHODS The blood flow response to hyperoxia and hypercapnia was evaluated in peripapillary retinal tissue superior and inferior to the optic nerve head using confocal scanning laser Doppler flowmetry. In 14 young, healthy persons, blood flow was measured while breathing room air and during isocapnic hyperoxia (100% O2 breathing) and isoxic hypercapnia (PCO2 increased 15% above baseline). Histograms were generated from pixel-by-pixel analysis of retinal portions of superior and inferior temporal quadrants of the entire image. RESULTS Baseline blood flow in the inferior temporal quadrant was significantly greater than in the superior temporal quadrant (P < 0.05). However, the inferior region failed to increase in perfusion during hypercapnia and experienced significant mean blood flow reduction; flow reduction in the pixels at the 25th, 50th, 75th, and 90th percentile of flow; and an increased percentage of pixels without measurable flow, during hyperoxia (each P < 0.05). In contrast, in the superior temporal region, hyperoxia failed to reduce blood volume, velocity, or flow, whereas hypercapnia significantly increased mean flow; increased flow in the pixels at the 25th, 50th, 75th, and 90th percentile of flow; and reduced the percentage of pixels without measurable flow (each P < 0.05). CONCLUSIONS The inferior temporal quadrant of the peripapillary retina is, in comparison with the superior temporas region, less responsive to vasodilation and more responsive to vasoconstriction. These differences could contribute to different susceptibility to visual field defect or vascular dysfunction in the superior and inferior retina.
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Ciulla TA, Harris A, Chung HS, Danis RP, Kagemann L, McNulty L, Pratt LM, Martin BJ. Color Doppler imaging discloses reduced ocular blood flow velocities in nonexudative age-related macular degeneration. Am J Ophthalmol 1999; 128:75-80. [PMID: 10482097 DOI: 10.1016/s0002-9394(99)00061-6] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE To study ocular perfusion defects in age-related macular degeneration. METHODS Twenty-five subjects with nonexudative age-related macular degeneration were compared with 25 age-matched control subjects in studies of flow velocities in several retrobulbar vessels. Color Doppler imaging, which was performed by an examiner who was masked to the subjects' assignment to the control or age-related macular degeneration group, measured peak systolic and end diastolic velocity in the ophthalmic, central retinal, and nasal and temporal posterior ciliary arteries of one eye. A resistive index was calculated from the peak systolic and end diastolic velocity. RESULTS Subjects with nonexudative age-related macular degeneration showed a consistent trend toward lower peak systolic and end-diastolic velocities in the posterior ciliary arteries. For example, in the nasal posterior ciliary artery, the mean end diastolic velocity measured 1.45 +/- 0.34 cm per sec in the age-related macular degeneration group compared with 1.96 +/- 0.66 cm per sec in the control group, yielding a 26% decrease in the age-related macular degeneration group, which represented the largest difference and was highly statistically significant (P = .0012). The resistive index was not significantly altered in the nasal or temporal posterior ciliary artery. Subjects with nonexudative age-related macular degeneration did not differ from control subjects in peak systolic velocity, end diastolic velocity, or resistive index in the ophthalmic artery. In the central retinal artery, the end diastolic velocity was lower (1.37 +/- 1.95 cm per sec vs 1.95 +/- 0.66 cm per sec), whereas the resistive index was higher (0.83 +/- 0.05 vs 0.76 +/- 0.06 cm per sec), in the age-related macular degeneration group; these results were highly statistically significant (P = .0007 and P < .0001, respectively). CONCLUSIONS Retrobulbar vascular changes in nonexudative age-related macular degeneration subjects include reduced flow velocities in the nasal and temporal posterior ciliary arteries. The reduced peak systolic velocity, combined with the reduced end diastolic velocity at a constant resistive index, seen in nonexudative age-related macular degeneration, is consistent with reduced bulk flow in these vessels, suggesting that choroidal perfusion is abnormal in this form of age-related macular degeneration. The changes in the central retinal artery suggest there may be a more generalized perfusion abnormality beyond the choroid in patients with age-related macular degeneration or that the central retinal artery exhibits a secondary autoregulatory response to a primary change elsewhere.
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Gerard MJ, Martin BJ. Post-effects of long-term hand vibration on visuo-manual performance in a tracking task. ERGONOMICS 1999; 42:314-326. [PMID: 10024850 DOI: 10.1080/001401399185676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Movement precision and performance time were evaluated through a visuo-manual tracking task performed before and after 10-min hand vibration exposure. Constant displacement amplitude vibration of 0.2 and 0.3 mm peak to peak at 90, 150, 300 Hz were applied to the hand z-axis by a vertical handle. During exposure a grip force of 5% MVC was exerted for 5 s and then relaxed for 25 s while maintaining fingers-handle contact. The tracking task consisted in moving a ring (phi = 9 mm) attached to a thin rod held between the index finger and thumb along a zig-zagged wire (phi = 3.7 mm). Alterations of tracking errors (ring-wire contact) and tracking time were analysed as a function of the vibration parameters. The tasks were performed by ten healthy participants. Vibration induced a significant increase in tracking errors (ring-wire contact) and a significant decrease in tracking time. These impairments decayed with time after vibration exposure. The recovery period was > 5 min but < 10 min with the exception of 90 Hz vibration, for which recovery could be > 10 min. The number of tracking errors was neither influenced by vibration frequency nor by amplitude. The tracking time decreased as frequency increased and recovery was related to the displacement amplitude. The subjective rating of the performance on a visual analogue scale indicated that the subjects tended to perceive the task as being easier after vibration exposure. Vibration applied to the non-dominant hand while the participant performed the tracking task had no effect. These results show that vibration similar to hand-tool vibration affects precision and velocity control of visually guided hand movements. Furthermore, these performance decrements were not consciously perceived.
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Lasley RD, Martin BJ, Valdivia HH, Mentzer RM, Bünger R. Metabolic inotropy and calcium transients in isolated rat cardiomyocytes. Ann N Y Acad Sci 1998; 853:308-10. [PMID: 10603966 DOI: 10.1111/j.1749-6632.1998.tb08286.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Martin BJ, Watkins JB, Ramsey J. Venipuncture in the medical physiology laboratory. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:S62-S67. [PMID: 9841567 DOI: 10.1152/advances.1998.274.6.s62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Medical physiology laboratories, traditionally devoted to animal experimentation, face unprecedented difficulties linked to cost, staffing, instrumentation, and the use of animals. At the same time, laboratory experiences with living creatures play a unique role in medical education. In this article we describe the use of venipuncture and subsequent blood analysis, with medical students serving as both subjects and experimenters, in a sequence of first-year physiology laboratories. These experiments are safe, robust, inexpensive, and time efficient, and they teach the principles of cardiovascular, respiratory, renal, nutritional, and gastrointestinal physiology. In addition, they enhance medical education in several other important dimensions. First, they teach safe venous blood collection and handling, a training appropriate for students at this level. Second, by serving each week as subjects as well as experimenters, students experience aspects of both sides of the doctor-patient relationship. Third, the laboratories can be used to teach fundamentals of research design and analysis. Finally, because blood analysis is central to medicine, and because the student's own blood data are discussed, students are enthusiastic and cooperative, and the clinical relevance of the data is clear.
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Arend O, Harris A, Arend S, Remky A, Martin BJ. The acute effect of topical beta-adrenoreceptor blocking agents on retinal and optic nerve head circulation. ACTA OPHTHALMOLOGICA SCANDINAVICA 1998; 76:43-9. [PMID: 9541433 DOI: 10.1034/j.1600-0420.1998.760108.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
PURPOSE Topical beta-blockers are the most common treatment for ocular hypertension in glaucoma, but their ocular hemodynamic effects are not well known. We investigated the acute effects of betaxolol (beta-1 selective antagonist), levobunolol (non-selective antagonist with active polar metabolite), and timolol (non-selective antagonist) on retinal and superficial optic nerve head circulation. METHODS Intraocular pressure (IOP), heart rate, blood pressure, and retinal circulation were evaluated in 12 healthy subjects (6F/6M; mean age=24+/-2 years) before and two hours after instillation of each drug on separate occasions at least two weeks apart. Macular capillary blood velocity (MCBV), epipapillary blood velocities (EBV), arteriovenous passage (AVP) times, and arterial and venous diameters were measured by digital image analysis of scanning laser fluorescein angiograms. RESULTS All drugs significantly (p<0.05) reduced IOP. There was no significant effect on blood pressure or calculated ocular perfusion pressure. Only levobunolol significantly lowered heart rate (p<0.05). Each drug produced a significant (p<0.01) decrease in AVP time of approximately 25%. MCBV was significantly (p<0.01) increased by approximately 20% in all three conditions; each drug also produced significant (p<0.01) increases in EBV. Arterial and venous diameters remained unaffected. CONCLUSION All three drugs, despite different beta-adrenergic properties, increased blood velocities in retinal and epipapillary capillaries. These changes, occurring as they do in concert with decreased retinal arteriovenous passage time at constant retinal arterial and venous diameter, may indicate improved retinal perfusion after drug treatment. Improved circulation, if it indeed occurs, in tandem with reduced IOP, might explain in part the beneficial effect of beta-adrenoreceptor blocking agents in glaucomatous patients.
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Martin BJ, Valdivia HH, Bünger R, Lasley RD, Mentzer RM. Pyruvate augments calcium transients and cell shortening in rat ventricular myocytes. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:H8-17. [PMID: 9458846 DOI: 10.1152/ajpheart.1998.274.1.h8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Pyruvate has been shown to be a metabolic inotrope in the myocardium. In millimolar concentrations, it has been shown to increase both myocardial phosphorylation potential and the cytosolic [NAD+]-to-[NADH] ratio. To determine if changes in these parameters can alter intracellular Ca2+ concentration ([Ca2+]i) and hence contractile function, Ca2+ transients and cell shortening (CS) were measured in isolated rat ventricular myocytes superfused with a physiological N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid buffer (11 mmol/l glucose) with and without additional pyruvate, L-lactate, acetate, or isoproterenol. The addition of 5 mmol/l pyruvate resulted in a 33% increase in CS and a 39% increase in systolic [Ca2+]i. These pyruvate effects were 70% of those observed with 100 nmol/l isoproterenol. The mitochondrial monocarboxylate transport inhibitor alpha-cyano-4-hydroxycinnamate (250 mumol/l) strongly inhibited pyruvate inotropy, suggesting a substantial obligatory coupling between pyruvate inotropism and its oxidation by the mitochondria. A possible role of the cytosolic [NAD+]-to-[NADH] ratio was assessed by comparing the effects of 20 mmol/l L-lactate to those of equimolar pyruvate. In contrast to 20 mmol/l pyruvate, excess L-lactate failed to appreciably increase CS or systolic [Ca2+]i. The findings imply that, at levels substantially above 5 mmol/l, a portion of pyruvate inotropism might be due to extreme cytosolic [NAD+]-to-[NADH] ratios. This study is the first evidence that augmented [Ca2+]i transients are most likely the mechanism of cardiac pyruvate inotropism.
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Rempel D, Serina E, Klinenberg E, Martin BJ, Armstrong TJ, Foulke JA, Natarajan S. The effect of keyboard keyswitch make force on applied force and finger flexor muscle activity. ERGONOMICS 1997; 40:800-808. [PMID: 9336104 DOI: 10.1080/001401397187793] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The design of the force-displacement characteristics or 'feel' of keyboard keyswitches has been guided by preference and performance data; there has been very little information on how switch 'feel' alters muscle activity or applied force. This is a laboratory-based repeated measures design experiment to evaluate the effect of computer keyboard keyswitch design on applied finger force and muscle activity during a typing task. Ten experienced typists typed on three keyboards which differed in keyswitch make force (0.34, 0.47 and 1.02 N) while applied fingertip force and finger flexor electromyograms were recorded. The keyboard testing order was randomized and subjects typed on each keyboard for three trials, while data was collected for a minimum of 80 keystrokes per trial. No differences in applied fingertip force or finger flexor EMG were observed during typing on keyboards with switch make force of 0.34 or 0.47 N. However, applied fingertip force increased by approximately 40% (p < 0.05) and EMG activity increased by approximately 20% (p < 0.05) when the keyswitch make force was increased from 0.47 to 1.02 N. These results suggest that, in order to minimize the biomechanical loads to forearm tendons and muscles of keyboard users, keyswitches with a make force of 0.47 N or less should be considered over switches with a make force of 1.02 N.
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Martin BJ, McClanahan TB, Van Wylen DG, Gallagher KP. Effects of ischemia, preconditioning, and adenosine deaminase inhibition on interstitial adenosine levels and infarct size. Basic Res Cardiol 1997; 92:240-51. [PMID: 9342431 DOI: 10.1007/bf00788519] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In order to examine the relationship between local adenosine concentrations before, during, and after ischemia and the extent of ischemic myocardial damage, measurements of interstitial fluid (ISF) nucleosides were made using microdialysis probes implanted in the ischemic region of isoflurane anesthetized Micropigs undergoing 60' coronary artery occlusion (CAO) and 3 h of reperfusion (REP). Nucleoside concentrations in the dialysate collected from the microdialysis probes were used as an index of ISF levels. Dialysate nucleoside concentrations (ADO, inosine and hypoxanthine), myocardial infarct size, and myocardial blood flow (MBF) were determined in control animals (n = 6), animals preconditioned with a single 10' cycle of CAO and REP (PC, n = 6), and those treated with the adenosine deaminase inhibitor pentostatin (n = 6, 0.2 mg/Kg i.v. 30' prior to CAO). The brief PC occlusion resulted in a transient but significant increase in dialysate ADO (6.7 +/- 1.8 microM vs. 0.67 +/- 0.1 microM at baseline). Pentostatin administration had no significant effect on either dialysate nucleosides or MBF at baseline. During the 60' CAO, dialysate ADO increased in control animals. In PC animals, however, dialysate ADO during CAO was lower than control. Pretreatment with pentostatin resulted in a six-fold augmentation in dialysate ADO during the 60 min CAO when compared to the control values (110.62 +/- 30.2 microM vs. 16.31 +/- 2.1 microM at 60 min of ischemia). Pentostatin also resulted in a significant reduction in the accumulation of inosine and hypoxanthine, indicating inhibition of adenosine deaminase activity. There were no significant differences in MBF between groups at any time point. Following 3 h REP, infarct size was 35.4 +/- 5.5%, 8.1 +/- 1.5% and 8.3 +/- 1.8% of the region at risk in control, PC, and pentostatin groups, respectively. These data suggest that marked increase in ISF ADO during CAO, may be as effective in reducing INF as a modest increase in ISF ADO prior to prolonged CAO.
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Martin BJ, Lasley RD, Mentzer RM. Infarct size reduction with the nucleoside transport inhibitor R-75231 in swine. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 272:H1857-65. [PMID: 9139972 DOI: 10.1152/ajpheart.1997.272.4.h1857] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Adenosine (Ado) has been reported to be cardioprotective in several models of myocardial ischemia. The nucleoside transport inhibitor R-75231 (R-75) has been reported to enhance local Ado concentrations and postischemic recovery of function, but little is known regarding its effects on myocardial infarct size. The purpose of the present study was to determine the effects of R-75 on infarct size and to measure myocardial regional Ado concentrations. Studies were conducted in pentobarbital-anesthetized swine undergoing 60 min of coronary artery occlusion and 2 h of reperfusion. Control pigs (n = 8) were compared with those receiving R-75 (0.1 mg/kg i.v.) 15 min before either occlusion (Pre R-75, n = 8) or reperfusion (Rep R-75, n = 8). Interstitial fluid (ISF) Ado, coronary venous Ado, and infarct size (% of the region at risk) were measured. In the Pre R-75 group, ISF Ado concentrations were significantly increased before and during ischemia, reaching a peak value of 71.8 +/- 8.6 microM (vs. 16.8 +/- 0.8 microM in control). ISF inosine and hypoxanthine concentrations were significantly reduced during ischemia in Pre R-75 animals. Infarct size was smaller in Pre R-75 compared with control (21.6 +/- 1.9 vs. 38.4 +/- 2.6%, P < 0.05). The Rep R-75 group had significantly elevated coronary venous Ado concentrations but no increases in ISF Ado or reduction in infarct size (33.5 +/- 3.5%). These data indicate that R-75 increases myocardial Ado and reduces infarct size when administered before coronary occlusion. The R-75-induced reduction in infarct size appears to be related to the augmentation of ISF Ado before ischemia rather than to increased plasma Ado during reperfusion.
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Evans DW, Harris A, Danis RP, Arend O, Martin BJ. Altered retrobulbar vascular reactivity in early diabetic retinopathy. Br J Ophthalmol 1997; 81:279-82. [PMID: 9215054 PMCID: PMC1722169 DOI: 10.1136/bjo.81.4.279] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
AIM/BACKGROUND In diabetic eye disease the factors leading to compromised circulation and the resulting loss of visual function are poorly understood. Although retinal circulation has been widely investigated, it accounts for only a fraction of total eye blood flow. Blood flow was investigated in the larger vessels feeding the eye in patients with early diabetic retinopathy. METHODS Eleven patients with early diabetes with minimal or no retinopathy and 11 healthy controls were evaluated for retrobulbar blood flow velocity using colour Doppler imaging for the ophthalmic and central retinal arteries. Patients and subjects were tested while breathing room air and again under conditions of isocapnic hyperoxia. RESULTS Hyperoxia induced a significant change in the central retinal artery end diastolic velocity (EDV) (p = 0.008) and resistance index (RI) (p = 0.032) in normal subjects, but not in diabetic patients. Consequently, during hyperoxia, the diabetic patients were significantly higher for EDV (p = 0.006) and significantly lower for RI (p = 0.002) compared with normal controls. Hyperoxia caused no significant change in either group in the ophthalmic artery; nevertheless, under isocapnic hyperoxia conditions the diabetic patients had lower peak systolic velocity (p = 0.05) and lower RI (p = 0.05) than normal subjects. CONCLUSIONS Imposition of isocapnic hyperoxia produces significant differences in the ophthalmic and central retinal artery blood flow velocities in diabetic patients with early disease when compared with normal subjects. These results demonstrate that diabetic patients with minimal or no retinopathy suffer from irregular ocular vascular function in the major vessels feeding the eye.
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Martin BJ, Lyon TD, Fell GS, McKay P. Erythrocyte magnesium in elderly patients: not a reliable guide to magnesium status. J Trace Elem Med Biol 1997; 11:44-8. [PMID: 9176871 DOI: 10.1016/s0946-672x(97)80009-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To assess body magnesium status in various illness states in older people by measurement of serum magnesium (S Mg) and erythrocyte magnesium (E Mg) and to explore the limitations of E Mg measurement. S Mg and E Mg were measured in 150 consecutive out-patients, mean age 77 years, and in 100 consecutive in-patient admissions, mean age 80 years. Results were analysed for different diagnostic groups S Mg was normally distributed for both in-patients and out-patients, mean values 0.79 mmol/l and 0.77 mmol/l respectively. In-patient E Mg concentrations were often higher but the distribution was considerably skewed, median 2.28 mmol/l, mean 2.35 mmol/l. Out-patient E Mg concentration followed a near normal distribution, median 2.32 mmol/l, mean 2.30 mmol/l. There was a significant correlation between E Mg and S Mg for out-patients, R = 0.29 (p < 0.001). In-patients with infections and pressure sores had significantly raised E Mg concentrations but normal or low S Mg. High E Mg concentrations in illness are likely to be due to alterations in characteristics of the erythrocytes themselves rather than an indication of body magnesium excess. E Mg concentrations in illness should be interpreted with caution.
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Abstract
An artificial neural network (ANN) was created to simulate lumbar muscle response to static moment loads. The network model was based on an abstract representation of a motor control system in which muscle activity is driven primarily to maintain moment equilibrium. The network model parameters were obtained by an iterative method (trained), using a modification of the standard backpropagation algorithm and moment equilibrium constraints. In contrast to previous ANN models of muscle activity, patterns of muscle activity are not target (training) values, but rather emerge as a result of moment equilibrium constraints. Assumptions regarding the moment generating capacity muscles and competitive interactions between muscles were employed and enabled the prediction of realistic patterns of muscle activity upon comparison with experimental electromyographic (EMG) data sets (r2: 0.4-0.9). The success of the simulation model suggests that a motor recruitment plan can be mimicked with relatively simple systems and that 'competition' between responsive units (muscles) may be intrinsic to the learning process. Prediction of alternative recruitment patterns and differing magnitudes of co-contractile activity were achieved by varying competition parameters within and between units.
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