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Relave F, Meulyzer M, Alexander K, Beauchamp G, Marcoux M. Comparison of radiography and ultrasonography to detect osteochondrosis lesions in the tarsocrural joint: a prospective study. Equine Vet J 2009; 41:34-40. [PMID: 19301579 DOI: 10.2746/042516408x343019] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
REASONS FOR PERFORMING STUDY Lesions located on the medial malleolus of the tarsocrural joint can be difficult to image radiographically. Ultrasonography allows evaluation of articular cartilage and subchondral bone. OBJECTIVES To compare dorso30 degrees lateral-plantaromedial-oblique (DL-PIMO) and dorso45 degrees views to detect lesions on the medial malleolus, to validate the use of ultrasonography to show lesions in the tarsocrural joint and to compare its sensitivity to radiography. METHODS Tarsocrural joints (n=111) with osteochondrosis were evaluated ultrasonographically and radiographically prior to arthroscopic lesion debridement. A complete radiographic examination was made and the best view to detect each lesion recorded. Longitudinal and transverse ultrasonography of the dorsal aspect of the joint was performed and the best scan plane to image each lesion recorded. RESULTS There were 94 joints with lesions on the distal intermediate ridge of tibia, 24 with lesions on the medial malleolus, and 4 with lesions on the lateral trochlear ridge. The sensitivity of radiography to detect lesions on the medial malleolus and distal intermediate ridge of tibia was 71 and 96%, respectively. Eighty-two percent of lesions on the medial malleolus were better imaged on dorso30 degrees view. The sensitivity of ultrasonography to detect lesions on the medial malleolus and distal intermediate ridge of tibia was 83 and 98%, respectively. Ultrasonography was significantly more sensitive than radiography to detect lesions on the medial malleolus and distal intermediate ridge of tibia. CONCLUSION Dorso30 degrees lateral-plantaromedial-oblique view was the best to image lesions on the medial malleolus. Ultrasonography was a valuable diagnostic tool to diagnose lesions in the tarsocrural joint and was more sensitive than radiography for lesions located on the medial malleolus and distal intermediate ridge of tibia. CLINICAL RELEVANCE Radiographic examination should include a dorso30 degrees view for detection of lesions on the medial malleolus and ultrasonography should be considered to diagnose osteochondrosis in the tarsocrural joints.
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Bouchgua M, Alexander K, Carmel EN, d'Anjou MA, Beauchamp G, Richard H, Laverty S. Use of routine clinical multimodality imaging in a rabbit model of osteoarthritis--part II: bone mineral density assessment. Osteoarthritis Cartilage 2009; 17:197-204. [PMID: 18757215 DOI: 10.1016/j.joca.2008.06.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Accepted: 06/25/2008] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To assess bone mineral density (BMD) at different depths from the articular surface in vivo and temporally in a rabbit model of osteoarthritis (OA) using clinical computed tomography (CT) equipment. METHODS The knee joints of rabbits (N=10 with Anterior cruciate ligament transection (ACLT) and contralateral sham joints, and N=6 unoperated controls) were scanned in a transverse image plane with a single-slice helical CT scanner. BMD was calculated at defined depths from the articular surface to the growth plate in the lateral femoral condyle (LFC), medial femoral condyle (MFC), lateral tibial plateau (LTP) and medial tibial plateau (MTP). Baseline BMD was measured at 2 weeks before surgery, and then repeated at weeks 2, 4 and 8 post-surgery in all 10 operated rabbits, and again at week 12 in five of the operated rabbits and at weeks -2 and 8 in the six control rabbits. RESULTS In the control joints, BMD decreased with increasing distance into the epiphysis and remained stable over time within each depth. A significant reduction in BMD was observed at week 2 post-operatively in three compartments (LFC, MFC and MTP) in the ACLT joints and persisted to week 12. A modest reduction in BMD occurred in the LTP and MTP of the sham joints at week 12 alone. CONCLUSION Clinical CT equipment permitted rapid, repeated, in vivo, non-invasive BMD assessment in a rabbit model of OA. A marked BMD reduction was measured with progression of OA until the end point at 12 weeks.
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Bouchgua M, Alexander K, d'Anjou MA, Girard CA, Carmel EN, Beauchamp G, Richard H, Laverty S. Use of routine clinical multimodality imaging in a rabbit model of osteoarthritis--part I. Osteoarthritis Cartilage 2009; 17:188-96. [PMID: 18760939 DOI: 10.1016/j.joca.2008.06.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Accepted: 06/25/2008] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To evaluate in vivo the evolution of osteoarthritis (OA) lesions temporally in a rabbit model of OA with clinically available imaging modalities: computed radiography (CR), helical single-slice computed tomography (CT), and 1.5 tesla (T) magnetic resonance imaging (MRI). METHODS Imaging was performed on knees of anesthetized rabbits [10 anterior cruciate ligament transection (ACLT) and contralateral sham joints and six control rabbits] at baseline and at intervals up to 12 weeks post-surgery. Osteophytosis, subchondral bone sclerosis, bone marrow lesions (BMLs), femoropatellar effusion and articular cartilage were assessed. RESULTS CT had the highest sensitivity (90%) and specificity (91%) to detect osteophytes. A significant increase in total joint osteophyte score occurred at all time-points post-operatively in the ACLT group alone. BMLs were identified and occurred most commonly in the lateral femoral condyle of the ACLT joints and were not identified in the tibia. A significant increase in joint effusion was present in the ACLT joints until 8 weeks after surgery. Bone sclerosis or cartilage defects were not reliably assessed with the selected imaging modalities. CONCLUSION Combined, clinically available CT and 1.5 T MRI allowed the assessment of most of the characteristic lesions of OA and at early time-points in the development of the disease. However, the selected 1.5 T MRI sequences and acquisition times did not permit the detection of cartilage lesions in this rabbit OA model.
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Frazier-Bowers S, Rincon-Rodriguez R, Zhou J, Alexander K, Lange E. Evidence of linkage in a Hispanic cohort with a Class III dentofacial phenotype. J Dent Res 2009; 88:56-60. [PMID: 19131318 DOI: 10.1177/0022034508327817] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Despite the prevalence of craniofacial disorders, the genetic contribution remains poorly understood. Class III malocclusion represents a specific craniofacial problem that can be handicapping, both functionally and socially. We hypothesized that the Class III phenotype is genetically linked to specific loci that regulate maxillary or mandibular growth. To determine the region linked to the Class III phenotype in four Hispanic families, we performed a genome-wide scan and linkage analysis using 500 microsatellite markers. Pedigree and linkage analyses revealed that the Class III phenotype (primarily maxillary deficiency) segregates in an autosomal-dominant manner, and that 5 loci (1p22.1, 3q26.2, 11q22, 12q13.13, and 12q23) are suggestive of linkage. Candidate genes within the 12q23 region (ZLR=2.93) include IGF1, HOXC, and COL2A1. Chromosome 1 results (ZLR=2.92) were similar to those reported previously in an Asian cohort with mandibular prognathism, suggesting that a common upstream genetic element may be responsible for both mandibular prognathism and maxillary deficiency.
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Koebnick C, Roberts CK, Shaibi GQ, Kelly LA, Lane CJ, Toledo-Corral CM, Davis JN, Ventura EE, Alexander K, Weigensberg MJ, Goran MI. Adiponectin and leptin are independently associated with insulin sensitivity, but not with insulin secretion or beta-cell function in overweight Hispanic adolescents. Horm Metab Res 2008; 40:708-12. [PMID: 18563679 DOI: 10.1055/s-2008-1077097] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The aim of the study was to investigate the independent effects of leptin and adiponectin on insulin sensitivity as well as insulin secretion and beta-cell function in overweight Hispanic adolescents. Despite pubertal changes in hormone secretion, studies investigating the independent effect of both hormones on insulin sensitivity and beta-cell function in adolescents are lacking. In a cross-sectional study, 175 overweight Hispanic adolescent boys (n=101) and girls (n=74) with a family history of diabetes were recruited and insulin sensitivity (SI), acute insulin response to glucose (AIR), disposition index (DI), body composition, total serum adiponectin, and leptin were assessed. Over age, leptin significantly increased in girls but not in boys (p for age x gender interaction=0.005) while adiponectin was similar in boys and girls. Leptin was not correlated to adiponectin. Leptin (partial r=-0.180; p=0.019) and adiponectin (partial r=0.230; p=0.003) predicted SI independent of age, gender, body fat, lean body mass, and Tanner stage but together, they explained 5% of the unique variation in SI (p for R (2)-change<0.001). Leptin or adiponectin were not related to AIR or DI. With regard to SI, AIR, and DI, no significant gender, age, or Tanner stage interactions were observed suggesting similar effects of adiponectin and leptin among gender, age, and Tanner stages. Leptin and adiponectin were independently associated with SI, but not with insulin secretion or beta-cell function.
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Alexander K. Experimentelle Voraussetzungen einer Korrelation von Kreislauf- und Stoffwechselgrössen beim Gliedmassenarterienverschluss des Menschen. J Vasc Res 2008. [DOI: 10.1159/000157788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Alexander K, Nissen P, Mitzkat H. Lichtplethysmographische Untersuchungen an Diabetikern und Stoffwechselgesunden. J Vasc Res 2008. [DOI: 10.1159/000157696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Alexander K, Hasse H. Untersuchungen zur Eignung trijodierter Röntgenkontrastmittel für die cerebrale Angiographie. J Vasc Res 2008. [DOI: 10.1159/000157584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Fischer M, Alexander K. Die Doppler-Sonographie der extrakraniellen Arteria carotis mit und ohne Doppier-Frequenz-Spektrum-Analyse. AKTUELLE NEUROLOGIE 2008. [DOI: 10.1055/s-2007-1020775] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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David F, Rougier M, Alexander K, Morisset S. Ultrasound-guided coxofemoral arthrocentesis in horses. Equine Vet J 2007; 39:79-83. [PMID: 17228601 DOI: 10.2746/042516407x153093] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
REASON FOR PERFORMING STUDY Coxofemoral joint pain is probably underestimated due to difficulties in identifying hip pain. The deep location of the joint and proximity of the sciatic nerve make arthrocentesis based on external landmarks a difficult and potentially risky procedure in mature horses. OBJECTIVES To describe an ultrasound-guided injection technique of the coxofemoral joint in standing horses and to evaluate its accuracy and potential difficulties/complications. METHODS Nine mature horses had both pelvic areas prepared for sterile ultrasound examination (3.5 MHz curvilinear probe). Coxofemoral joints were located and penetrated at their craniodorsolateral aspect under ultrasonographic guidance and injected with sterile contrast medium. A standing ventrodorsal radiographic view of each hemipelvis centred on the hip was obtained for each horse to assess the injection site. Horses were evaluated for 10 days following injection for possible complications. RESULTS Intra-articular injection was successful in all 18 joints. The procedure was well tolerated by horses under minimal restraint. Mean +/- s.d. needle repositionings required before accurate placement was 1.5 +/- 1.3 per joint. Once the needle was in the joint, synovial fluid was obtained in 7/18 joints. Minimal periarticular contrast medium was detected in 2/18 joints. Mean +/- s.d. ultrasonographic examination time required for coxofemoral localisation, accurate needle positioning and injection was 4.3 +/- 2.1 min. No complications were observed in the 10 days following injection. CONCLUSION The ultrasound-guided coxofemoral arthrocentesis is an accurate, reliable and safe technique that offers a real time evaluation of needle introduction into the deep and narrow coxofemoral joint space. POTENTIAL RELEVANCE Although this technique remains to be tested on clinical cases, it is a promising tool to facilitate diagnosis of coxofemoral pain, septic arthritis or administration of intra-articular medication.
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Kipping RR, Hamilton S, Roderick M, Alexander K. Developing audit standards required for outbreaks of communicable diseases—lessons from a mumps outbreak. J Public Health (Oxf) 2006; 28:347-50. [PMID: 17065178 DOI: 10.1093/pubmed/fdl065] [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: 11/14/2022] Open
Abstract
BACKGROUND A mumps outbreak occurred in 2004-05 in England and Wales. The outbreak in the Avon area of England led to mass vaccination of 16- to 24-year-olds with the measles, mumps and rubella vaccine (MMR). The response to the outbreak was audited. Literature and web searches for audit standards were undertaken, and experts in the field were contacted. No comprehensive audit standards for outbreaks of communicable diseases were found. This article describes an approach to developing audit standards for outbreaks of communicable diseases. METHODS Audit standards were developed based on the memorandum of understanding between the National Health Service (NHS) and Health Protection Agency. The audit was undertaken involving 25 staff. RESULTS The audit standards developed identified many areas for improvement including training, strategic co-ordination, inter-organizational communication, consistency and timeliness of communication. Conducting the audit was problematic because there were not pre-defined audit standards. CONCLUSIONS Audit standards should be developed, which include issues relating to the structure, process and outcome of responses to outbreaks. The development of audit standards for the management of outbreaks is crucial to evaluate outbreak control and make necessary improvements.
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Desai J, Alexander K, Riga A. Characterization of polymeric dispersions of dimenhydrinate in ethyl cellulose for controlled release. Int J Pharm 2006; 308:115-23. [PMID: 16326055 DOI: 10.1016/j.ijpharm.2005.10.034] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Revised: 10/27/2005] [Accepted: 10/31/2005] [Indexed: 10/25/2022]
Abstract
Granulations of dimenhydrinate (DMH) were prepared using various concentrations of ethyl cellulose (EC) by the solid dispersion technique. Characterization was done using thermal analysis, powder X-ray diffraction, infrared spectroscopy, optical microscopy and dissolution studies. Humidity studies were performed to investigate the effect of moisture on the drug and solid dispersions. It was seen that the crystalline drug was converted into its amorphous form in all the granulations. There was no chemical interaction between the DMH and EC. The thermal decomposition of drug in the granules was not affected. Dissolution studies revealed that the drug release from the granulations was significantly reduced as compared to the pure drug. As the amount of ethyl cellulose increased, the drug release rate decreased and the drug release kinetics showed a better fit to zero-order kinetics. Humidity studies showed that the drug and granulations remained stable in conditions not exceeding 70%RH. At high humidity of 100%RH, there was formation of the hydrate crystal forms of the drug in the pure drug samples and granules with 1:1 DMH-EC content whereas the granules with higher polymer content did not show any significant changes indicating better drug stability in the granules.
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Alexander K, Levine MW. Temporal frequency characteristics of period doubling in the cone flicker ERG. J Vis 2002. [DOI: 10.1167/2.10.108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Van Asperen P, Cahill A, Alexander K, Henry R. Discharge guidelines for children with acute asthma: a consensus statement. J Paediatr Child Health 2001; 37:539-41. [PMID: 11903830 DOI: 10.1046/j.1440-1754.2001.00762.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Lee CH, Daanen JF, Jiang M, Yu H, Kohlhaas KL, Alexander K, Jarvis MF, Kowaluk EL, Bhagwat SS. Synthesis and biological evaluation of clitocine analogues as adenosine kinase inhibitors. Bioorg Med Chem Lett 2001; 11:2419-22. [PMID: 11549437 DOI: 10.1016/s0960-894x(01)00454-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adenosine kinase (AK) is the primary enzyme responsible for adenosine metabolism. Inhibition of AK effectively increases extracellular adenosine concentrations and represents an alternative approach to enhance the beneficial actions of adenosine as compared to direct-acting receptor agonists. Clitocine (3), isolated from the mushroom Clitocybe inversa, has been found to be a weak inhibitor of AK. We have prepared a number of analogues of clitocine in order to improve its potency and demonstrated that 5'-deoxy-5'-amino-clitocine (7) improved AK inhibitory potency by 50-fold.
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Mulugu S, Potnis A, Shamsuzzaman, Taylor J, Alexander K, Bastia D. Mechanism of termination of DNA replication of Escherichia coli involves helicase-contrahelicase interaction. Proc Natl Acad Sci U S A 2001; 98:9569-74. [PMID: 11493686 PMCID: PMC55493 DOI: 10.1073/pnas.171065898] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2001] [Indexed: 11/18/2022] Open
Abstract
Using yeast forward and reverse two-hybrid analyses, we have discovered that the replication terminator protein Tus of Escherichia coli physically interacts with DnaB helicase in vivo. We have confirmed this protein-protein interaction in vitro. We show further that replication termination involves protein-protein interaction between Tus and DnaB at a critical region of Tus protein, called the L1 loop. Several mutations located in the L1 loop region not only reduced the protein-protein interaction but also eliminated or reduced the ability of the mutant forms of Tus to arrest DnaB at a Ter site. At least one mutation, E49K, significantly reduced Tus-DnaB interaction and almost completely eliminated the contrahelicase activity of Tus protein in vitro without significantly reducing the affinity of the mutant form of Tus for Ter DNA, in comparison with the wild-type protein. The results, considered along with the crystal structure of Tus-Ter complex, not only elucidate further the mechanism of helicase arrest but also explain the molecular basis of polarity of replication fork arrest at Ter sites.
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Gautam A, Mulugu S, Alexander K, Bastia D. A single domain of the replication termination protein of Bacillus subtilis is involved in arresting both DnaB helicase and RNA polymerase. J Biol Chem 2001; 276:23471-9. [PMID: 11313334 DOI: 10.1074/jbc.m009537200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The current models that have been proposed to explain the mechanism of replication termination are (i) passive arrest of a replication fork by the terminus (Ter) DNA-terminator protein complex that impedes the replication fork and the replicative helicase in a polar fashion and (ii) an active barrier model in which the Ter-terminator protein complex arrests a fork not only by DNA-protein interaction but also by mechanistically significant terminator protein-helicase interaction. Despite the existence of some evidence supporting in vitro interaction between the replication terminator protein (RTP) and DnaB helicase, there has been continuing debate in the literature questioning the validity of the protein-protein interaction model. The objective of the present work was two-fold: (i) to reexamine the question of RTP-DnaB interaction by additional techniques and different mutant forms of RTP, and (ii) to investigate if a common domain of RTP is involved in the arrest of both helicase and RNA polymerase. The results validate and confirm the RTP-DnaB interaction in vitro and suggest a critical role for this interaction in replication fork arrest. The results also show that the Tyr(33) residue of RTP plays a critical role both in the arrest of helicase and RNA polymerase.
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Alexander K, Hinds PW. Requirement for p27(KIP1) in retinoblastoma protein-mediated senescence. Mol Cell Biol 2001; 21:3616-31. [PMID: 11340156 PMCID: PMC86983 DOI: 10.1128/mcb.21.11.3616-3631.2001] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2000] [Accepted: 03/14/2001] [Indexed: 01/21/2023] Open
Abstract
In vivo and in vitro evidence indicate that cells do not divide indefinitely but instead stop growing and undergo a process termed cellular proliferative senescence. Very little is known about how senescence occurs, but there are several indications that the retinoblastoma protein (pRb) is involved, the most striking being that reintroduction of RB into RB(-/-) tumor cell lines induces senescence. In investigating the mechanism by which pRb induces senescence, we have found that pRb causes a posttranscriptional accumulation of the cyclin-dependent kinase inhibitor p27(KIP1) that is accompanied by an increase in p27(KIP1) specifically bound to cyclin E and a concomitant decrease in cyclin E-associated kinase activity. In contrast, pRb-related proteins p107 and p130, which also decrease cyclin E-kinase activity, do not cause an accumulation of p27(KIP1) and induce senescence poorly. In addition, the use of pRb proteins mutated in the pocket domain demonstrates that pRb upregulation of p27(KIP1) and senescence induction do not require the interaction of pRb with E2F. Furthermore, ectopic expression of p21(CIP1) or p27(KIP1) induces senescence but not the morphology change associated with pRb-mediated senescence, uncoupling senescence from the morphological transformation. Finally, the ability of pRb to maintain cell cycle arrest and induce senescence is reversibly abrogated by ablation of p27(KIP1) expression. These findings suggest that prolonged cell cycle arrest through the persistent and specific inhibition of cdk2 activity by p27(KIP1) is critical for pRb-induced senescence.
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Chatterjee K, Dollimore D, Alexander K. A new application for the Antoine equation in formulation development. Int J Pharm 2001; 213:31-44. [PMID: 11165092 DOI: 10.1016/s0378-5173(00)00644-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Characterization of formulation components in pre-formulation and formulation studies will be made easier if a rapid method to evaluate the evaporation characteristics of an ingredient in the formulation is developed. This study aims at providing a simple and rapid thermogravimetric method for estimating the vapor pressure characteristics using the Antoine equation as the analytical tool. The heat treatment for the majority of benzoic acid derivatives follows zero-order rate processes that are in good correlation with their evaporation process. The optimum conditions for the rising temperature experiments were found when the heating rate was 10 degrees C/min in an atmosphere of dry nitrogen (100 ml/min). Methyl paraben was taken as the calibration compound since its Antoine constants are reported in the literature, and its selected thermodynamic parameters were evaluated using the Langmuir equation. The coefficient of vaporization (k macro) was determined to be 124,525+/-0.8, with units being reported in the S.I. system. The corresponding vapor-pressure plots were obtained for the remaining compounds and their Antoine constants calculated.
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Jarvis MF, Yu H, Kohlhaas K, Alexander K, Lee CH, Jiang M, Bhagwat SS, Williams M, Kowaluk EA. ABT-702 (4-amino-5-(3-bromophenyl)-7-(6-morpholinopyridin-3-yl)pyrido[2, 3-d]pyrimidine), a novel orally effective adenosine kinase inhibitor with analgesic and anti-inflammatory properties: I. In vitro characterization and acute antinociceptive effects in the mouse. J Pharmacol Exp Ther 2000; 295:1156-64. [PMID: 11082453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
Adenosine (ADO) is an inhibitory neuromodulator that can increase nociceptive thresholds in response to noxious stimulation. Inhibition of the ADO-metabolizing enzyme adenosine kinase (AK) increases extracellular ADO concentrations at sites of tissue trauma and AK inhibitors may have therapeutic potential as analgesic and anti-inflammatory agents. ABT-702 is a novel and potent (IC(50) = 1. 7 nM) non-nucleoside AK inhibitor that has several orders of magnitude selectivity over other sites of ADO interaction (A(1), A(2A), A(3) receptors, ADO transporter, and ADO deaminase). ABT-702 was 1300- to 7700-fold selective for AK compared with a number of other neurotransmitter and peptide receptors, ion channel proteins, neurotransmitter/nucleoside reuptake sites, and enzymes, including cycloxygenases-1 and -2. ABT-702 was equipotent (IC(50) = 1.5 +/- 0. 3 nM) in inhibiting native human AK (placenta), two human recombinant isoforms (AK(long) and AK(short)), and AK from monkey, dog, rat, and mouse brain. Kinetic studies revealed that AK inhibition by ABT-702 was competitive with respect to ADO and noncompetitive with respect to MgATP(2-). AK inhibition by ABT-702 was demonstrated to be reversible after 4 h of dialysis. ABT-702 is orally active and fully efficacious in reducing acute somatic nociception (ED(50) = 8 micromol/kg i.p.; 65 micromol/kg p.o.) in the mouse hot-plate assay. ABT-702 also dose dependently reduced nociception in the phenyl-p-quinone-induced abdominal constriction assay. The antinociceptive effects of ABT-702 in the hot-plate assay were blocked by the nonselective ADO receptor antagonist theophylline, and by the A(1)-selective antagonist cyclopentyltheophylline (10 mg/kg i.p.), but not by a peripherally selective ADO receptor antagonist 8-(p-sulfophenyl)-theophylline (50 mg/kg i.p.), by the A(2A)-selective antagonist 3, 7-dimethyl-1-propargylxanthine (1 mg/kg i.p.) or the opioid antagonist naloxone (5 mg/kg i.p.). Thus, ABT-702 is a novel and potent non-nucleoside AK inhibitor that effectively reduces acute thermal nociception in the mouse by a nonopioid, non-nonsteroidal anti-inflammatory drug, ADO A(1) receptor-mediated mechanism.
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Alexander K. Part time GPs. AUSTRALIAN FAMILY PHYSICIAN 2000; 29:1016. [PMID: 11127054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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Burke D, Alexander K, Baxter M, Baker F, Connell K, Diggles S, Feldman K, Horny A, Kokinos M, Moloney D, Withers J. Rehabilitation of a person with severe traumatic brain injury. Brain Inj 2000; 14:463-71. [PMID: 10834341 DOI: 10.1080/026990500120565] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
A case study report of a long and intensive rehabilitation programme for a young woman after she sustained a severe diffuse axonal injury in a motor vehicle accident is described in detail. The purpose of this paper is to encourage specialist brain injury rehabilitation services to offer extended rehabilitation programmes to patients, even with very severe injuries. Significant functional improvements and enhanced quality of life frequently reward the high cost and hard work involved.
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Alexander K, Clarkson PJ. Good design practice for medical devices and equipment, Part II: Design for validation. J Med Eng Technol 2000; 24:53-62. [PMID: 10937360 DOI: 10.1080/030919000409311] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Medical devices and their associated process equipment must be reliable and fit for purpose. In light of the recent changes to the medical device regulations, manufacturers must now take an integrated approach to design, development and validation. Good design practice encourages this integrated approach while ensuring fitness for purpose within commercial reality. A review of current literature related to good design practice carried out in Part I of this paper showed that there is inadequate guidance regarding the integration of validation with design. This paper proposes a practical approach to design for validation aimed at making devices easier and more economic to validate. The approach comes in the form of a model of design for validation that illustrates the basic relationship between design, development and validation and a series of design tactics that were formulated in order to help designers take a more proactive approach to validation during design.
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Jan S, Mooney G, Ryan M, Bruggemann K, Alexander K. The use of conjoint analysis to elicit community preferences in public health research: a case study of hospital services in South Australia. Aust N Z J Public Health 2000; 24:64-70. [PMID: 10777981 DOI: 10.1111/j.1467-842x.2000.tb00725.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
AIMS To demonstrate the use of conjoint analysis (CA) in public health research through a survey of the South Australian community about aspects of their public hospital services. METHODS A series of focus groups determined the most important attributes in choice of hospital services. These were built into a CA survey, using the discrete choice approach. The survey was posted to a representative sample of 700 South Australians. Theoretical validity, internal consistency and non-response bias were all investigated. RESULTS Some 231 individuals returned the questionnaire. The attribute, 'improvement in complication rates' was positively associated with choice of hospital. Three attributes were found to be negatively associated with such choice: 'waiting times for casualty', 'waiting times for elective surgery' and, anomalously, 'parking and transport facilities'. 'Travel time' and the cost attribute, 'Medicare levy' were not statistically significant. Trade-offs between the significant attributes were estimated, as were satisfaction or utility scores for different ways of providing hospital services. Results concerning internal consistency and internal validity were encouraging, but some potential for non-response bias was detected. CONCLUSION A high premium is placed on the quality of hospital care and members of the community are prepared to choose between hospitals largely on the basis of outcomes and length of waiting times for elective surgery and in casualty. IMPLICATIONS CA can yield potentially policy-relevant information about community preferences for health services.
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Alexander K, Clarkson PJ. Good design practice for medical devices and equipment, Part I: A review of current literature. J Med Eng Technol 2000; 24:5-13. [PMID: 10849882 DOI: 10.1080/030919000293987] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Changes to the medical device regulations within the past few years have forced medical device manufacturers to take an integrated approach to design and validation in order to ensure that their products are reliable and fit for purpose. Good design practice encourages fitness for purpose within commercial reality. This paper contains a review of the current literature that is relevant to good design practice. The results show that there is inadequate guidance regarding the integration of validation with design. Thus, there is a need for good design practice to include 'design for validation' which is aimed at designing medical devices to make them easier and more economic to validate. Research has been carried out at the Cambridge Engineering Design Centre in order to develop an approach that provides guidance in order to help designers achieve integrated design, development and validation. This will be reported in part II of this paper.
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Alexander K, Niforatos W, Bianchi B, Burgard EC, Lynch KJ, Kowaluk EA, Jarvis MF, van Biesen T. Allosteric modulation and accelerated resensitization of human P2X(3) receptors by cibacron blue. J Pharmacol Exp Ther 1999; 291:1135-42. [PMID: 10565834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
The activity of ATP as a fast neurotransmitter is mediated by the P2X family of ligand-gated ion channels. P2X receptor subtypes are subject to functional modulation by a diverse set of factors, including pH, divalent cations, and temperature. The human P2X(3) (hP2X(3)) receptor subunit is expressed primarily in sensory ganglia where it exists as either a homomultimeric receptor or, in combination with P2X(2), as a heteromultimeric receptor. This article describes the allosteric modulatory effect of the putative P2X receptor antagonist cibacron blue on the activity of recombinant hP2X(3) receptors. In 1321N1 cells expressing the hP2X(3) receptor, cibacron blue mediated a 3- to 7-fold increase in both the magnitude and the potency of ATP-activated Ca(2+) influx and transmembrane currents. The half-maximal concentration of cibacron blue required to mediate maximal potentiation (EC(50) = 1.4 microM) was independent of the agonist used to activate the hP2X(3) receptor. The nonselective P2 receptor antagonist PPADS (pyridoxal-5-phosphate-6-azophenyl-2',4'-disulfonic acid) caused a rightward shift of the cibacron blue concentration-effect curve, whereas increasing concentrations of cibacron blue attenuated PPADS antagonism. In addition to potentiating the effects of ATP at the hP2X(3) receptor, cibacron blue also produced a 6-fold increase in the rate of hP2X(3) receptor recovery from desensitization (from T(1/2) = 15.9 to 2.6 min), as evidenced by its ability to restore ATP responsiveness to acutely desensitized receptors. Consistent with the properties of other ligand-gated ion channels, these results suggest that hP2X(3) receptor activity can be allosterically modulated by a ligand distinct from the endogenous agonist.
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Alexander K, Clarkson J, Bishop D. Observations on medical device design, Part II: Good practice. MEDICAL DEVICE TECHNOLOGY 1999; 10:24-8. [PMID: 10724775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Current guidance on design is inadequate. This second article in a two-part series presents a framework for good design practice that attempts to improve designers' awareness of manufacturing and validation issues. Seven design tactics, derived from observations of current industry practice and design literature, seek to encourage good practice and achieve safer, more profitable devices.
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Clarkson J, Alexander K, Bishop D. Observations on medical device design, Part I: Current practice. MEDICAL DEVICE TECHNOLOGY 1999; 10:28-31. [PMID: 10623354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Medical devices must be designed and proven to be fit for the purpose that they were intended. Good design practice ensures this fitness for purpose and is reflected in the commercial success of products. This two-part article focuses on current industry design practice and proposes that there are significant benefits to be obtained by defining good design practice: better products and reduced development costs.
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Lanphear BP, Howard C, Eberly S, Auinger P, Kolassa J, Weitzman M, Schaffer SJ, Alexander K. Primary prevention of childhood lead exposure: A randomized trial of dust control. Pediatrics 1999; 103:772-7. [PMID: 10103301 DOI: 10.1542/peds.103.4.772] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Dust control is recommended as one of the primary strategies to prevent or control children's exposure to residential lead hazards, but the effect of dust control on children's blood lead levels is poorly understood. OBJECTIVE To determine the effectiveness of dust control in preventing children's exposure to lead, as measured by blood lead levels, during their peak age of susceptibility. DESIGN A randomized, controlled trial. SETTING Rochester, NY. PARTICIPANTS A total of 275 urban children were randomized at 6 months of age, of whom 246 (90%) were available for the 24-month-old follow-up visit. INTERVENTIONS Children and their families were randomly assigned to an intervention group (n = 140), which received cleaning equipment and up to eight visits by a dust control advisor, or a control group (n = 135). OUTCOME MEASURES Geometric mean blood lead levels and prevalence of elevated blood lead levels (ie, >10 microg/dL, 15 microg/dL, and 20 microg/dL). RESULTS At baseline, children's geometric mean blood lead levels were 2.9 microg/dL (95% confidence interval [CI] = 2.7, 3.1); there were no significant differences in characteristics or lead exposure by group assignment, with the exception of water lead levels. For children in the intervention group, the mean number of visits by a dust control advisor during the 18-month study period was 6.2; 51 (36%) had 4 to 7 visits, and 69 (49%) had 8 visits. At 24 months of age, the geometric mean blood lead was 7.3 microg/dL (95% CI = 6.6, 8.2) for the intervention group and 7.8 microg/dL (95% CI = 6.9, 8. 7) for the control group. The percentage of children with a 24-month blood lead >/=10 microg/dL, >/=15 microg/dL, and >/=20 microg/dL was 31% versus 36%, 12% versus 14%, and 5% versus 7% in the intervention and control groups, respectively. CONCLUSIONS We conclude that dust control, as performed by families and in the absence of lead hazard controls to reduce ongoing contamination from lead-based paint, is not effective in the primary prevention of childhood lead exposure.
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Brondolo E, Karlin W, Alexander K, Bobrow A, Schwartz J. Workday communication and ambulatory blood pressure: implications for the reactivity hypothesis. Psychophysiology 1999; 36:86-94. [PMID: 10098383 DOI: 10.1017/s0048577299961565] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Ambulatory blood pressure monitoring was used to investigate the cardiovascular correlates of naturally occurring interpersonal interactions. Participants were New York City traffic agents, who routinely engage in conflict-prone communication with the public under relatively fixed conditions. Talking with the public, supervisors, or coworkers was associated with levels of systolic and diastolic blood pressure and heart rate that exceeded a resting baseline. Blood pressure was higher when agents were talking to the public than when they were talking to coworkers or engaged in a noncommunicative work task. Systolic blood pressure response during communication was associated with the agent's mood. Blood pressure effects associated with communication appear to persist after the communication has ceased. Implications of these data for the reactivity hypothesis of the pathogenesis of cardiovascular disease are discussed.
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Böger RH, Bode-Böger SM, Thiele W, Creutzig A, Alexander K, Frölich JC. Restoring vascular nitric oxide formation by L-arginine improves the symptoms of intermittent claudication in patients with peripheral arterial occlusive disease. J Am Coll Cardiol 1998; 32:1336-44. [PMID: 9809945 DOI: 10.1016/s0735-1097(98)00375-1] [Citation(s) in RCA: 190] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Administration of L-arginine improves nitric oxide (NO) formation and endothelium-dependent vasodilation in atherosclerotic patients. OBJECTIVES We investigated in this double-blind, controlled study whether prolonged intermittent infusion therapy with L-arginine improves the clinical symptoms of patients with intermittent claudication, as compared with the endothelium-independent vasodilator prostaglandin E1, and control patients. METHODS Thirty-nine patients with intermittent claudication were randomly assigned to receive 2 x 8 g L-arginine/day, or 2 x 40 microg prostaglandin E1 (PGE1)/day or no hemodynamically active treatment, for 3 weeks. The pain-free and absolute walking distances were assessed on a walking treadmill at 3 km/h, 12% slope, and NO-mediated, flow-induced vasodilation of the femoral artery was assessed by ultrasonography at baseline, at 1, 2 and 3 weeks of therapy and 6 weeks after the end of treatment. Urinary nitrate and cyclic guanosine-3', 5'-monophosphate (GMP) were assessed as indices of endogenous NO production. RESULTS L-Arginine improved the pain-free walking distance by 230+/-63% and the absolute walking distance by 155+/-48% (each p < 0.05). Prostaglandin E1 improved both parameters by 209+/-63% and 144+/-28%, respectively (each p < 0.05), whereas control patients experienced no significant change. L-Arginine therapy also improved endothelium-dependent vasodilation in the femoral artery, whereas PGE1 had no such effect. There was a significant linear correlation between the L-arginine/asymmetric dimethylarginine (ADMA) ratio and the pain-free walking distance at baseline (r=0.359, p < 0.03). L-Arginine treatment elevated the plasma L-arginine/ADMA ratio and increased urinary nitrate and cyclic GMP excretion rates, indicating normalized endogenous NO formation. Prostaglandin E1 therapy had no significant effect on any of these parameters. Symptom scores assessed on a visual analog scale increased from 3.51+/-0.18 to 83+/-0.4 (L-arginine) and 7.0+/-0.5 (PGE1; each p < 0.05), but did not significantly change in the control group (4.3+/-0.4). CONCLUSIONS Restoring NO formation and endothelium-dependent vasodilation by L-arginine improves the clinical symptoms of intermittent claudication in patients with peripheral arterial occlusive disease.
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Thum J, Caspary L, Creutzig A, Alexander K. Intra-arterial and intravenous administration of prostaglandin E1 cause different changes to skin microcirculation in patients with peripheral arterial occlusive disease. VASA 1998; 27:100-5. [PMID: 9612114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Disturbed skin microcirculation in patients with peripheral arterial occlusive disease (PAOD) might be affected by prostaglandin E1 (PGE1). The purpose of this study was to investigate local skin perfusion at the forefoot and toe of PAOD patients during different modes of administration of PGE1. PATIENTS AND METHODS In 17 patients with severe PAOD local intradermal haemoglobin oxygen saturation (SHB) and dermal vascular reserve capacity, transcutaneous oxygen pressure (tcPO2) and laser Doppler flux (LDF) were determined during intra-arterial (1.5 ng/kg body weight/min) and intravenous (6 ng/kg body weight/min) infusion of PGE1. RESULTS SHB significantly increased at both locations during intravenous PGE1; intra-arterial administration significantly increased SHB in the skin of the forefoot only. Reserve capacity increased during intravenous administration and was markedly reduced during intra-arterial infusion. No significant changes were found regarding tcPO2 and LDF. CONCLUSIONS These data suggest different therapeutic mechanisms for intra-arterial and intravenous administered of PGE1.
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Schellong SM, Burchert W, Böger RM, Creutzig A, Hundeshagen H, Alexander K. Prostaglandin E1 in peripheral vascular disease: a PET study of muscular blood flow. Scand J Clin Lab Invest 1998; 58:109-17. [PMID: 9587162 DOI: 10.1080/00365519850186689] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Increase of blood flow in the ischaemic leg is believed to represent the main action of prostaglandin E1 (PGE1) in the therapy of peripheral vascular disease (PVD). There is no reliable data in man concerning the amount of increase in muscular blood flow (MBF) of the calf, and the difference between intra-arterial and intravenous application. PATIENTS AND METHODS We conducted a positron emission tomography (PET) study of MBF with 15O-water as flow tracer. Fifteen patients with PVD and three healthy volunteers were given 5 micrograms PGE1 intra-arterially over 50 min; PET scans were taken at 0, 25 and 50 min. Additionally, eight of the patients were investigated during an intravenous infusion of 40 micrograms PGE1 over 120 min; PET scans were taken at 0, 30, 60 and 120 min. RESULTS Increase of muscular blood flow by intra-arterial PGE1 averaged 80%. A steal phenomenon was not observed. The amount of flow enhancement depended on whether or not the femoral artery was patent. During intravenous PGE1, muscular blood flow remained unchanged. CONCLUSIONS In man, the pharmacodynamic profile of intra-arterial PGE1 differs clearly from intravenous PGE1. The flow-enhancing property is lost during metabolization in the lung. Since no difference exists between the therapeutic efficacy of intraarterial and intravenous PGE1, the impact on muscular blood flow is not as important as suggested previously.
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Kinney LaPier TL, Sirotnak N, Alexander K. Aerobic exercise for a patient with chronic multisystem impairments. Phys Ther 1998; 78:417-24. [PMID: 9555924 DOI: 10.1093/ptj/78.4.417] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Many patients with long-term disabilities have inactive lifestyles that put them at risk for chronic diseases and secondary disabilities. The purpose of this case report is to illustrate the process of aerobic exercise prescription for a patient with chronic multisystem impairments. The patient was a 43-year-old man who incurred a traumatic brain injury and multiple fractures in a motorcycle accident 15 years previously. He subsequently developed heterotopic ossification around the right hip. In addition, the patient had a history of smoking. We chose a "nontraditional" mode of exercise for the patient that we believed would be safe and effective and would accommodate his neurologic and orthopedic impairments. The mode of exercise used was an apparatus in which the upper and lower extremities alternately flexed and extended in a nonreciprocal fashion. The patient attended 12 exercise sessions over a 1-month period, during which he demonstrated acute and chronic physiological responses appropriate for the exercise stimulus.
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Theaux H, McCartney J, Alexander K, Cooper R. Six-month-olds' discrimination of information in infant-directed speech. Infant Behav Dev 1998. [DOI: 10.1016/s0163-6383(98)91931-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Alexander JH, Alexander K, Kong DF, Tung CY, Whellan D. Session highlights from the American Heart Association Scientific Sessions: November 9-12, 1997. Am Heart J 1998; 135:157-80. [PMID: 9453536 DOI: 10.1016/s0002-8703(98)70357-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Abstract
This paper deals with the knowledge base employed in resource allocation. It deliberately distinguishes between 'thick-textured' and 'thin-textured' knowledge. A thick-textured view of change in the health sector accounts for the history, civic goods and variety of human needs and passions which rationalist economics defines out as a thin-textured matter of individual choices in a free market. The narrative material begins with a discussion of health service policy-making in South Australia and elsewhere in the 1980s and 1990s, then proceeds to a discussion of priority-setting literature, which we regard as thin-textured. We offer two accounts of approaches to setting priorities in health care which we think have overcome some of the deficiencies of the thin-textured approach.
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Schellong SM, Böger RH, Burchert W, Bode-Böger SM, Galland A, Frölich JC, Hundeshagen H, Alexander K. Dose-related effect of intravenous L-arginine on muscular blood flow of the calf in patients with peripheral vascular disease: a H215O positron emission tomography study. Clin Sci (Lond) 1997; 93:159-65. [PMID: 9301431 DOI: 10.1042/cs0930159] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
1. Endothelium-derived nitric oxide (NO) contributes to the regulation of vascular tone and blood pressure. Infusion of L-arginine produces systemic vasodilatation via stimulation of endogenous NO formation. Vasodilatation is accompanied by an increase in peripheral arterial blood flow. However, it is not known whether capillary nutritive blood flow increases as well. The time course and dose-response pattern of this effect remain to be elucidated. 2. Two groups of ten patients with peripheral vascular disease (PVD) received an intravenous infusion of 8 g or 30 g of L-arginine over a period of 40 min. Blood pressure and heart rate were monitored non-invasively. Muscular blood flow (MBF) of the calf was determined at 0, 20, 40, 60, 80 min by positron emission tomography with H215O as flow tracer. Plasma L-arginine and cyclic GMP (cGMP) levels were determined at the same time points. 3. L-arginine induced a dose-related decrease in blood pressure during the infusion period. MBF and plasma cGMP levels during and after the infusion of 8 g of L-arginine did not change significantly. In the patients receiving 30 g of L-arginine, MBF was enhanced significantly from 1.56 +/- 0.14 to 2.09 +/- 0.21 ml min-1 100 ml-1 at 40 min and 2.23 +/- 0.15 ml min-1 100 ml-1 after 80 min (+43.0%). The increase in MBF was paralleled by an increase in plasma cGMP from 4789.8 +/- 392.2 nmol/l at baseline to 9223.2 +/- 1233.6 nmol/l at 40 min. 4. We conclude that intravenous L-arginine enhances nutritive capillary MBF in patients with PVD via the NO-cGMP pathway in a dose-related manner. This effect might be therapeutically beneficial in patients with PVD.
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Meier M, Caspary L, Creutzig A, Alexander K. Vital capillary microscopy of skin areas at the forefoot of diabetic patients using intraarterial injection of Na-fluorescein. INTERNATIONAL JOURNAL OF MICROCIRCULATION, CLINICAL AND EXPERIMENTAL 1997; 17:190-7. [PMID: 9378569 DOI: 10.1159/000179228] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A modified technique of vital capillary microscopy with intraarterial application of Na-fluorescein has been introduced in the study of nutritional skin microcirculation to assess skin microcirculation of different diabetic patients, comprising one group without neurocutaneous complications (group 2; n = 9), one suffering only from neuropathy (group 3; n = 9) and one with trophic skin lesions in the contralateral foot (group 4; n = 8), all without macroangiopathy, compared to healthy controls (group 1; n = 9). Femoroarterial injection of small boli (10 mg) of Na-fluorescein allowed repeated investigation of the dye appearance times (AT) and capillary-filling times of forefoot skin capillaries within small periods of time before, during and after reactive hyperemia. At rest, AT was significantly shorter in patients of group 4 (16.8 +/- 4.4 s; p < 0.05) compared with groups 1-3 (34.3 +/- 12.8; 31.7 +/- 11.7 and 35.9 +/- 15.3 s). Fifteen seconds after the end of arterial occlusion, dye propagation to the skin was markedly accelerated in groups 1-3 (19.8 +/- 14.0; 14.4 +/- 7.6 and 18.7 +/- 10.6 s, respectively; p < 0.001), but prolonged in group 4 (18.4 +/- 7.4 s). After 10 min, the values at rest were reestablished. No differences between the four groups were found concerning capillary density and morphology. It is concluded that the development of skin lesions in diabetic patients without significant macroangiopathy may be favored by hyperperfusion and impaired vasoregulation. Intraarterial dye injection presents a valuable tool to assess dynamic alterations of the microcirculation at the level of skin capillaries.
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Alexander K. Ten strategies for creating successful managed care relationships. HEALTHCARE FINANCIAL MANAGEMENT : JOURNAL OF THE HEALTHCARE FINANCIAL MANAGEMENT ASSOCIATION 1997; 51:48, 50. [PMID: 10167842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Among the many customers providers serve are managed care organizations. The strategic relationships providers develop with these payers greatly influence the long-term success of both organizations. Providers can implement 10 strategies to improve their managed care relationships: focusing on contracting with selected managed care organizations, fostering positive relationships, coordinating contract participation, establishing communication links, educating providers about managed care, providing high-quality customer service; understanding operating costs, demonstrating value, maintaining flexibility, and pursuing alternative competitive relationships with caution. At the same time, managed care organizations can implement the same strategies to develop win/win relationships with providers.
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Böger RH, Bode-Böger SM, Thiele W, Junker W, Alexander K, Frölich JC. Biochemical evidence for impaired nitric oxide synthesis in patients with peripheral arterial occlusive disease. Circulation 1997; 95:2068-74. [PMID: 9133517 DOI: 10.1161/01.cir.95.8.2068] [Citation(s) in RCA: 315] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND We studied urinary nitrate and cGMP excretion rates, indices of systemic NO formation, and plasma concentrations of L-arginine and the endogenous NO synthase inhibitor asymmetrical dimethylarginine (ADMA) and its inactive stereoisomer, symmetrical dimethylarginine, in 77 patients with peripheral arterial occlusive disease (PAOD) in Fontaine stages IIb through IV and in 47 young and 37 elderly healthy control subjects. METHODS AND RESULTS Urinary nitrate excretion was 182.0+/-11.4 micromol/mmol creatinine and cGMP excretion was 186.2+/-13.0 nmol/mmol creatinine in young healthy control subjects. In elderly control subjects, both excretion rates were slightly lower (nitrate, 156.0+/-7.8 micromol/mmol creatinine; cGMP, 150.0+/-8.3 nmol/mmol creatinine; P=NS). In PAOD patients, there was a significant, progressive reduction of urinary nitrate (IIb, 138.4+/-11.9; III, 128.6+/-11.3; and IV, 91.9+/-8.0 micromol/mmol creatinine; P<.05) and cGMP (IIb, 139.9+/-25.2; III, 115.6+/-13.1; and IV, 76.9+/-7.9 nmol/mmol creatinine; P<.05) excretion rates related to the Fontaine stage of PAOD. These changes were independent of changes in renal excretory function. Plasma L-arginine concentrations were not significantly different between the groups, but ADMA concentrations were elevated in PAOD patients (young control subjects, 1.25+/-0.11; elderly control subjects, 1.01+/-0.05 micromol/L; IIb, 2.62+/-0.24; III, 3.06+/-0.48; and IV, 3.49+/-0.26 micromol/L; P<.05 for PAOD versus control subjects). There was a significant linear correlation between urinary nitrate and cGMP excretion rates and a significant negative linear correlation between plasma ADMA concentrations and urinary nitrate excretion. CONCLUSIONS In PAOD patients, there is a progressive reduction in urinary nitrate and cGMP excretion rates, which may be caused in part by accumulation of ADMA, an endogenous inhibitor of NO synthase.
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Appiah R, Hiller S, Caspary L, Alexander K, Creutzig A. Treatment of primary Raynaud's syndrome with traditional Chinese acupuncture. J Intern Med 1997; 241:119-24. [PMID: 9077368 DOI: 10.1046/j.1365-2796.1997.91105000.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Evaluation of the effects of a standardized acupuncture treatment in primary Raynaud's syndrome. DESIGN A controlled randomized prospective study. SETTING A winter period of 23 weeks, angiological clinic of Hannover Medical School. SUBJECTS Thirty-three patients with primary Raynaud's syndrome (16 control, 17 treatment). INTERVENTIONS The patients of the treatment group were given seven acupuncture treatments during the weeks 10 and 11 of the observation period. MAIN OUTCOME MEASURES All patients kept a diary throughout the entire observation period noting daily frequency, duration and severity of their vasospastic attacks. A local cooling test combined with nailfold capillaroscopy was performed for all patients at baseline (week 1) and in weeks 12 and 23, recording flowstop reactions of the nailfold capillaries. RESULTS The treated patients showed a significant decrease in the frequency of attacks from 1.4 day-1 to 0.6 day-1, P < 0.01 (control 1.6 to 1.2, P = 0.08). The overall reduction of attacks was 63% (control 27%, P = 0.03). The mean duration of the capillary flowstop reaction decreased from 71 to 24 s (week 1 vs. week 12, P = 0.001) and 38 s (week 1 vs. week 23, P = 0.02) respectively. In the control group the changes were not significant. CONCLUSIONS These findings suggest that traditional Chinese acupuncture is a reasonable alternative in treating patients with primary Raynaud's syndrome.
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Burchert W, Schellong S, van den Hoff J, Meyer GJ, Alexander K, Hundeshagen H. Oxygen-15-water PET assessment of muscular blood flow in peripheral vascular disease. J Nucl Med 1997; 38:93-8. [PMID: 8998159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
UNLABELLED To assess quantitatively regional nutritive muscular blood flow in patients with peripheral vascular disease (PVD), we evaluated the utility of PET with 15O-water. METHODS Eight healthy volunteers and 16 patients with angiographically proven PVD were studied. Regional blood flow of the calf was measured with 15O-water PET during rest, after intra-arterial infusion of prostaglandin E1 and during ergometry. The studies were quantified using a one tissue compartment model. RESULTS Normalized mean tracer uptake from 15-60 sec correlated closely (r = 0.98) with absolute blood flow. Scan times longer than 90 sec were required to determine blood flow reliably. The flow values were overestimated by 2% if arterial blood volume was neglected or if the input function delay was corrected globally for parametric imaging. Mean blood flow of calf muscles at rest did not differ significantly between patients (0.017 +/- 0.006 ml/min/ml) and control subjects (0.018 +/- 0.010 ml/min/ml). In PVD patients, blood flow increased by 100% after intra-arterial infusion of PGE1 in the respective leg. In the control subjects, average flow increased by a factor of six during exercise. The increase was more pronounced in the extensor muscles (0.182 +/- 0.031 ml/min/ml) than in flexor muscles (0.121 +/- 0.045 ml/min/ml). Due to the specific type of ergometry, superficial flexors exhibited higher flow values than the profound ones. CONCLUSION PET with 15O-water enables reliable determination of regional nutritive skeletal muscle blood flow for research and clinical applications in patients with PVD.
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Thum J, Caspary L, Creutzig A, Stappler T, Alexander K. Non-invasive determination of dermal hemoglobin oxygenation and concentration in patients with peripheral arterial occlusive disease. VASA 1997; 26:11-7. [PMID: 9068263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Oxygen saturation (SHB) and concentration (CHB) of dermal hemoglobin are important parameters for the supply of the skin. They may be non-invasively assessed by means of reflection photometry as hemoglobin is predominantly contributing to the skin reflection spectrum. METHODS AND RESULTS Dermal reflection spectra from the middle of the forefoot and from the tip of the toe of 20 healthy subjects and 61 patients suffering from peripheral arterial occlusive disease (PAOD) were recorded and compared to transcutaneous oxygen pressure (tcPO2). SHB, and tcPO2 were significantly higher in controls: compared to patients (ankle pressure (AP) > 50 mmHg) SHB in the skin of the forefoot was 63.8 vs. 54.5% (p < 0.05), CHB was 0.89 vs. 0.62 aU (p < 0.01). In the great toe SHB was 92.9 vs. 59.9% (p < 0.001), CHB was 2.21 vs. 0.92 aU (p < 0.001). Heating the skin of the forefoot to 44 degrees C yields local dermal vascular reserve capacity: SHB and CHB increased in all healthy subjects (96.4%; 1.44 aU, respectively). SHB decreased at the forefoot in 14 and at the toe in 18 of 21 patients with AP < 50 mmHg. At the toe decrease was found in 50 of 61 patients (sensitivity 82%, specificity 100%). CONCLUSIONS Local vascular reserve capacity of dermal perfusion is reduced in patients with PAOD, depending on AP. It should be determined preferably in patients with severe PAOD.
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95
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Creutzig A, Freund M, Caspary L, Alexander K. Microangiopathy in patients with chronic myelogenous leukemia treated with interferon. Microvasc Res 1996; 52:288-92. [PMID: 8954870 DOI: 10.1006/mvre.1996.0066] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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96
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Wieczorek I, Farber A, Alexander K. Hypothenar hammer syndrome successfully managed with intravenous prostaglandin E1 and heparin and with correction of the thrombogenic risk profile. A case report. Angiology 1996; 47:1111-6. [PMID: 8921762 DOI: 10.1177/000331979604701113] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A fifty-one-year-old man presented with a history, symptoms, and clinical findings typical of a hypothenar hammer syndrome in his dominant hand. A thrombotic obstruction in the distal section of the ulnar artery with multiple downstream occlusions of proper digital arteries were documented angiographically. Coexistence of additional cardiovascular risk factors (smoking-induced polycythemia, obesity, hypercholesterolemia, and hypertension) was identified. Conservative management with intravenous heparin and prostaglandin E1 together with measures directed at controlling the additional risk factors (repeated venesection, immediate smoking cessation, and low-lipid diet) resulted in a striking clinical and angiographic improvement of the digital perfusion, without resort to interventional measures or thrombolysis.
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97
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Thum J, Caspary L, Creutzig A, Alexander K. A new method for the assessment of tissue hemoglobin oxygenation in patients with chronic venous insufficiency. Microvasc Res 1996; 51:317-26. [PMID: 8992231 DOI: 10.1006/mvre.1996.0030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Venous incompetence often leads to ulceration of the skin of the lower limb due to a disturbance of skin microcirculation. We investigated 10 healthy subjects and 18 patients with chronic venous insufficiency by means of a fast scanning reflection photometer and determined noninvasively the hemoglobin oxygen saturation (S(HB)) and the relative concentration of hemoglobin (C(HB)) in the skin of the forefoot and at the calf, 10 cm proximal of the inner malleolus during positional changes. In supine position no significant differences were found. During sitting and standing S(HB) dropped and was significantly lower in patients at both locations (calf, standing, patients 22.2 +/- 10.6% vs controls 48.2 +/- 13.5%, P < 0.001). C(HB) increased in patients during standing from 0.71 to 2.13 +/- 0.33 aU (in controls from 0.69 to 1.49 +/- 0.28 aU, P < 0.001). Activation of the muscle pump decreased C(HB) and increased S(HB) in patients and in controls. After the movements were stopped, S(HB) decreased again and fell to the initial low values eight times faster in patients (7.4 +/- 5.3 vs 57.5 +/- 19.6 sec, P < 0.001). C(HB) increased four times faster in patients (7.2 +/- 6.1 vs 29.9 +/- 13.6 sec). In sitting and standing positions hemoglobin oxygenation in the skin of the lower limb was markedly reduced in patients, but normal perfusion conditions were restored in supine position, indicating reversibility of the changes. Reflection oxymetry seems a valuable tool for the assessment of chronic venous insufficiency. The substantially reduced oxygenation of dermal hemoglobin in standing patients may contribute to the development of venous ulcers.
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98
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Caspary LA, Creutzig A, Alexander K. Orthostatic vasoconstrictor response in patients with occlusive arterial disease assessed by laser Doppler flux and transcutaneous oximetry. Angiology 1996; 47:165-73. [PMID: 8595012 DOI: 10.1177/000331979604700208] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Posturally induced microvascular constriction normally causes a decrease of transcutaneous oxygen pressure (tcPO2) and laser Doppler flux (LDF) measured on the forefoot at 37 degrees C. The authors used both methods to assess the vasoconstrictor response (VCR) in 31 patients with various degrees of peripheral arterial occlusive disease (PAOD) and analyzed factors that could have influenced the response. Disturbed VCR was indicated by a signal increase following leg dependency, which occurred significantly more often in tcPO2 than in LDF measurements (69% vs 32%, P < 0.001). Correspondingly the median sitting/supine ratio was 2.4 for tcPO2 and 0.7 for LDF (P < 0.0001). Age and clinical stage had no influence on the VCR. With ankle artery pressures below 50 mmHg an increase of LDF was more probable. TcPO2 predominantly increased with ankle artery pressure up to 100 mmHg, though the sitting/supine ratio of tcPO2 was correlated with ankle artery pressure. In nondiabetics the response of tcPO2 but not of LDF was influenced by the values at rest. Differences between the two methods may be explained in part by their different sample volumes. The authors assume that tcPO2 is predominantly monitoring a local myogenic response while LDF is reflecting venoarteriolar response.
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99
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Bode-Böger SM, Böger RH, Alfke H, Heinzel D, Tsikas D, Creutzig A, Alexander K, Frölich JC. L-arginine induces nitric oxide-dependent vasodilation in patients with critical limb ischemia. A randomized, controlled study. Circulation 1996; 93:85-90. [PMID: 8616947 DOI: 10.1161/01.cir.93.1.85] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND L-Arginine is the precursor of endogenous nitric oxide (NO), which is a potent vasodilator acting via the intracellular second-messenger cGMP. In healthy humans, L-arginine induces peripheral vasodilation and inhibits platelet aggregation due to an increased NO production. Prostaglandin E1 (PGE1) induces peripheral vasodilation via stimulating prostacyclin receptors. METHODS AND RESULTS We investigated the effects of one intravenous infusion of L-arginine (30 g, 60 minutes) or PGE1 (40 microgram, 60 minutes) versus those of placebo (150 mL 0.9% saline, 60 minutes) on blood pressure, peripheral hemodynamics, and urinary NO3- and cGMP excretion rates in patients with critical limb ischemia (peripheral arterial occlusive disease stages Fontaine III or IV). Blood flow in the femoral artery was significantly increased by L-arginine (+42.3 +/- 7.9%, P<.05) and by PGE1 (+31.0 +/- 10.2%, P<.05) but not by placebo (+4.3 +/- 13.0%, P=NS). Urinary NO3- excretion increased by 131.8 +/- 39.5% after L-arginine (P<.05) but only by 32.3 +/- 17.2% after PGE1 (P=NS). Urinary cGMP excretion increased by 198.7 +/- 84.9% after L-arginine (P<.05) and by 94.2 +/- 58.8% after PGE1 (P=NS). Both urinary index metabolites were unchanged by placebo. CONCLUSIONS We conclude that intravenous L-arginine induces NO-dependent peripheral vasodilation in patients with critical limb ischemia. These effects are paralleled by increased urinary NO3- and cGMP excretion, indicating an enhanced systemic NO production. Increased urinary NO3- excretion may be a sum effect of NO synthase substrate provision (L-arginine) and increased shear stress (PGE1 and L-arginine).
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100
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Caspary L, Creutzig A, Alexander K. [How often is thrombolytic therapy of deep pelvic-leg venous thrombosis indicated?]. MEDIZINISCHE KLINIK (MUNICH, GERMANY : 1983) 1995; 90:618-22. [PMID: 8569627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND For patients with deep vein thrombosis new thrombolytic regimes are being proposed and demand evaluation in controlled studies. We tested prospectively, how many patients in internal medicine are candidates for thrombolysis. PATIENTS AND METHODS All available patients with the diagnosis of deep vein thrombosis (DVT) in lower extremities who were admitted to the service of internal medicine in a medium-sized hospital during one year were prospectively evaluated for the indication of fibrinolysis therapy according to the established criteria. RESULTS A total of 62 patients were enrolled. Fibrinolysis was not proposed in 25 patients aged over 70 years nor in another 9 patients in whom the thrombosis was restricted to calf veins. Nine additional cases had a recurrence of DVT (n = 4) or a history of more than 14 days. Among the remaining 19 patients, fibrinolysis was not performed in 11 because of advanced malignomas (n =4) or other diseases (n = 3) with limited life expectance, enhanced probability of haemorrhage (n = 3) and obvious non-compliance (n = 1). Eight patients were offered thrombolytic therapy, but 5 of them denied consent after being comprehensively informed. CONCLUSION Obviously by far most of patients admitted to internal medicine for DVT are candidates for standard heparin therapy only.
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