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Biomedical subjects

D Thomas

Publications and source records attributed to D Thomas.

At least 37 records · Page 2Linked to original sources

[Treatment of obstructive aortic atheroma in homozygotic familial hypercholesterolemia].

The object of this report is to describe the surgical treatment of a rare clinical form of homozygotic familial hypercholesterolaemia (HFH) associating valvular and supravalvular stenosis with coronary ostial stenosis. Three patients, two male and one female, aged 15, 23 and 41 respectively, suffering from HFH diagnosed in early childhood, presented with obstacles to left ventricular ejection and myocardial ischaemia due to coronary ostial stenosis. Surgery consisted of corrections in a single procedure of all abnormalities by aortic valve replacement, ascending aortic replacement and widening of the coronary artery ostia which were reimplanted on the aortic tube. The postoperative course of all three patients was favourable. Postoperative echocardiography showed the normal position of the valvular prosthesis, normalisation of the left ventricular ejection fraction with no significant residual obstruction. Angioscan of the coronary arteries showed a good result of coronary ostial widening. The authors conclude that HFH is a rare condition and that disease of the ascending aorta is common in this variety with involvement of the aortic valve, the ascending aorta and the coronary ostia. The surgical procedure described by the authors allows correction of all the abnormalities with the hope of a good long-term result.

Adolescent↗

Manpower problems.

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Delivery of Health Care↗

Epidermal-skin-test 1,000 (EST-1,000)--a new reconstructed epidermis for in vitro skin corrosivity testing.

The determination of a possible corrosive or irritative potential of certain products and ingredients is necessary for their classification and labeling requirements. Reconstructed skin as a model system provides fundamental advantages to single cell culture testing and leads to promising results as shown by different validation studies (for review: Fentem, J.H., Botham, P.A., 2002. ECVAM's activities in validating alternative tests for skin corrosion and irritation. ATLA 30(Suppl. 2), 61-67). In this study we introduce our new reconstructed epidermis "Epidermal-Skin-Test" (EST-1,000). This fully grown epidermis consists of proliferating as well as differentiating keratinocytes. EST-1,000 shows a high comparability to normal human skin as shown by histological and immunohistochemical data. Characteristic markers (KI-67, CK 1/10/5/14, transglutaminase, collagen IV, involucrin, beta 1 integrin) can be identified easily. The main focus of this work was to characterize EST-1,000 especially with respect to its barrier function by testing several substances of known corrosive potential. Skin corrosion was detected by the cytotoxic effect of the substances on a reconstructed epidermis after short-term application to the stratum corneum. The effect was determined by standard MTT assay and accompanying histological analysis. Hence EST-1,000 shows a very high predictive potential and closes the gap between animal testing and the established full-thickness model Advanced-Skin-Test 2,000 (AST-2,000) (Noll, M., Merkle, M.-L., Kandsberger, M., Matthes, T., Fuchs, H., Graeve, T., 1999. Reconstructed human skin (AST-2,000) as a tool for pharmaco-toxicology. ATLA 27, 302).

Acrylates↗

[Molecular basis of primary electrical heart diseases].

The last decade has seen rapid progress in our understanding of the molecular basis of arrhythmias, particularly concerning hereditary arrhythmia syndromes. This has led to significant improvement regarding differentiation, risk stratification and therapy in these patients and their families. However, there is mounting evidence that the knowledge obtained by studying these rare monogenic disorders will also enable us to dissect the molecular mechanisms underlying polygenetic and multi-factorial arrhythmias that are by far more common in clinical practice. The goal of this review is to give a brief overview of current knowledge on the molecular basis of primary electrical heart diseases. A focus is on the long QT syndrome.

Action Potentials↗

Outcomes of macular hole surgery: implications for surgical management and clinical governance.

PURPOSE: The optimal method and timing of the surgical treatment for idiopathic macular holes remains unknown. The aim of this retrospective study was to identify factors associated with anatomical and visual success in macular hole surgery. METHODS: Case records of 55 patients undergoing macular hole surgery at three units in the 2-year period up to July 2002 were reviewed to identify factors associated with anatomical and visual success. The following potential prognosticators were evaluated: patient age, hole stage, hole latency prior to surgery, preoperative acuity, simultaneous phacoemulsification, and intraocular lens implantation, internal limiting membrane peeling with and/or without indocyanine green, and postoperative posturing. RESULTS: The duration of preoperative symptoms, indocyanine green-assisted internal limiting membrane peeling, hole stage, and better preoperative visual acuity were associated with both anatomical success and regaining a postoperative visual acuity of 6/12 or better. DISCUSSION: The closure rate in patients undergoing surgery within 1 year of onset was 94.0%, and in those waiting 1 year or more it was 47.4%. Clinical governance and quality issues should dictate that NHS macular hole surgery is available to all within 1 year of onset. This study showed no adverse effect of ICG dye retinal staining. The results support the use of a 'patient-friendly' approach of simultaneous cataract surgery with no prone postoperative posturing.

Adult↗

[Comparison of homogenous strain-analysis with wall thickening for the MR tomographic assessment of regional myocardial function].

PURPOSE: To compare strain analysis and wall thickening (WT) analysis in differentiating the infarcted, adjacent, and remote zones in a rat model of myocardial infarction (MI). MATERIAL AND METHODS: Three normal (NL) and ten rats subjected to myocardial infarction were imaged on a 4.7T scanner. Gradient-echo and SPAMM-tagged cine images were acquired at three short axis levels of the left ventricle (LV). A homogenous strain analysis (principal strains lambda1 and lambda2, displacement D, angle beta) and a WT-analysis (mm- and %-thickening) were performed in all slices demonstrating MI. Regional function was compared between infarcted rats (infarcted, adjacent and remote zone) and corresponding regions in the NL rats. Additional segmental analysis was performed in the NL rats for the anterior, lateral, inferior and septal wall. RESULTS: In the NL rats, lambda (1) (greatest radial thickening) was greatest in the lateral and anterior wall. WT-analysis showed a pattern of function similar to lambda1, however, regional differences using WT-analysis were not significant. lambda (2) (greatest circumferential shortening) was most negative in the anterior wall. D was greatest in the lateral and inferior wall. The angle beta was radially directed in all segments. In the infarcted rats, both strain and WT-analyses revealed significant impairment in function in the infarcted and adjacent zones as compared to NL (p < 0.001). However, only the strain analysis (lambda1, lambda2, p < 0.001) detected significant remote myocardial dysfunction. Myocardial function differed significantly between the infarcted and adjacent and between the infarcted and remote regions. Strain analysis (lambda2, D, beta, p < 0.001) also identified significant functional differences between the adjacent and remote zones, however, no statistically significant differences were found using WT-analysis. CONCLUSION: Strain analysis is superior to WT-analysis in detecting regional functional variations in NL rats and in discriminating function in the infarcted, adjacent and remote zones post MI.

Algorithms↗

Molecular diversity of Proteus mirabilis isolates producing extended-spectrum beta-lactamases in a French university hospital.

Between February 1997 and December 2002, 3340 hospitalised patients yielded samples positive for Proteus mirabilis, of whom 45 (1.3%) were colonised/infected by P. mirabilis producing extended-spectrum beta-lactamases (ESBLs). The gross incidence of patients colonised/infected by ESBL-producing P. mirabilis was 1.61/10(5) days of hospitalisation, with 20% of isolates being collected from patients in urology wards, most frequently (53.3%) from urine samples. Seventeen (37.7%) of the 43 isolates were obtained from samples collected within 48 h of hospitalisation, indicating that they were community-acquired. Isoelectric focusing assays and sequencing identified the TEM-24, TEM-92 and TEM-52 ESBLs. Pulsed-field gel electrophoresis revealed eight pulsotypes (I-VIII), with the two most common pulsotypes, IV and VI, comprising ten (23.3%) and 12 (26.6%) isolates, respectively. These pulsotypes were considered to represent epidemic strains and spread in various wards of the hospital.

Anti-Bacterial Agents↗

Altered immunophenotypic parameters in infertile women. Possible role of herpes viremia.

PROBLEM: Purpose of this study was to reveal any alteration in peripheral blood lymphocytic concentrations of a large cohort of infertile women and to investigate the possible role of herpes viremia in the peripheral immunostimulation. METHOD OF STUDY: The immunophenotypic characteristics and the presence of herpes viruses DNA in the peripheral blood of 168 infertile women were studied. RESULTS: Peripheral CD56+/CD16+ natural killer (NK) cell concentration, CD56+/CD16- NK cell concentration, white blood cell (WBC) concentration and lymphocyte concentration were statistically correlated to herpes viremia. Epstein-Barr virus (EBV) viremia is related with a limited reduction of CD56+/CD16- cell levels in the peripheral blood of infertile women with regard to the rest of herpes viruses. High T-lymphocyte concentration, CD4+ T-cell concentration and CD8+ T-cell concentration was observed in women positive for three different kinds of herpes viruses (triple viremia) in the peripheral blood. CONCLUSIONS: Assuming that all women under study remained asymptomatic, these data suggest that subclinical herpesvirus viremia may be an important cause of peripheral immunostimulation in women with a history of infertility.

Adult↗

Prevalence, causes, and outcome at 2 years of age of newborn encephalopathy: population based study.

OBJECTIVES: To ascertain the prevalence of newborn encephalopathy in term live births, and also the underlying diagnoses, timing, and outcome at 2 years of surviving infants. DESIGN: Population based observational study. SETTING: North Pas-de-Calais area of France, January to December 2000. PATIENTS: All 90 neonates with moderate or severe newborn encephalopathy. RESULTS: The prevalence of moderate or severe newborn encephalopathy was 1.64 per 1000 term live births (95% confidence interval (CI) 1.30 to 1.98). The prevalence of birth asphyxia was 0.86 per 1000 term live births (95% CI 0.61 to 1.10). The main cause of newborn encephalopathy was birth asphyxia, diagnosed in 47 (52%) infants. It was associated with another diagnosis in 11/47 cases (23%). The timing was intrapartum in 56% of cases, antepartum in 13%, ante-intrapartum in 10%, and postpartum in 2%. In 19% of cases, no underlying cause was identified during the neonatal course. Twenty four infants died in the neonatal period, giving a fatality rate of 27% (95% CI 17% to 36%). Three infants died after the neonatal period. At 2 years of age, 38 infants had a poor outcome, defined by death or severe disability, a prevalence of 0.69 per 1000 term live births (95% CI 0.47 to 0.91). In infants with isolated birth asphyxia, this prevalence was 0.36 per 1000 term live births (95% CI 0.20 to 0.52). CONCLUSIONS: The causes of newborn encephalopathy were heterogeneous but the main one was birth asphyxia. The prevalence was low, but the outcome was poor, emphasising the need for prevention programmes and new therapeutic approaches.

Age Factors↗

A randomised controlled feasibility trial of vitrectomy versus laser for diabetic macular oedema.

AIM: (1) To evaluate whether vitrectomy is preferable to further macular laser in improving visual acuity and resolving retinal thickening in patients with diabetic macular oedema (DMO) despite previous laser and no macular traction. (2) To determine the feasibility of further trials in this population in terms of magnitude of comparative clinical effect, rate of recruitment, and loss to follow up. METHODS: A randomised controlled feasibility study. Patients with DMO and a visual acuity of 0.3 logMAR (6/12) or worse after one or more macular laser treatments were randomised on a 1:1 basis to either pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling or further macular laser. Patients with a posterior vitreous detachment, biomicroscopic evidence of retinal traction, or a taut thickened posterior hyaloid (TTPH) were excluded. Primary outcome measures were (1) best corrected logMAR visual acuity, (2) mean central macular thickness on optical coherence tomography, and (3) rate of recruitment and loss to follow up. Analysis was on an intention to treat basis. RESULTS: 19 patients were randomised to PPV and 21 to further macular laser. The mean baseline logMAR visual acuity was 0.65 (SD 0.28) for the group randomised to PPV and 0.60 (0.23) for the group randomised to laser. The mean change in best corrected visual acuity of the vitrectomy group was deterioration by 0.05 logMAR, while in the control group the mean change was an improvement of 0.03 logMAR. The median (interquartile range) baseline central macular thickness was 403 (337, 492) for the group randomised to PPV and 387 (298, 491) for the controls randomised to laser. The median change in central macular thickness from baseline to review in the vitrectomy group was a thinning by 73 mum (20%) and by 29 mum (10.7%) in the control laser group. This single centre was able to recruit 40 patients in 18 months with follow up of 82% at 1 year. CONCLUSION: A randomised controlled trial was found to be potentially feasible in this population, the rate of recruitment was however slow and one in five patients were lost to follow up because of death and ill health. These data provide little evidence in terms of visual acuity and macular thickness of any benefit of vitrectomy over further macular laser in patients with an attached hyaloid, DMO despite previous laser, and no clinically evident macular traction or TTPH.

Aged↗

Laboratory animals and the art of empathy.

Consistency is the hallmark of a coherent ethical philosophy. When considering the morality of particular behaviour, one should look to identify comparable situations and test one's approach to the former against one's approach to the latter. The obvious comparator for animal experiments is non-consensual experiments on people. In both cases, suffering and perhaps death is knowingly caused to the victim, the intended beneficiary is someone else, and the victim does not consent. Animals suffer just as people do. As we condemn non-consensual experiments on people, we should, if we are to be consistent, condemn non-consensual experiments on animals. The alleged differences between the two practices often put forward do not stand up to scrutiny. The best guide to ethical behaviour is empathy--putting oneself in the potential victim's shoes. Again to be consistent, we should empathise with all who may be adversely affected by our behaviour. By this yardstick, too, animal experiments fail the ethical test.

Animal Experimentation↗

Identification and characterisation of a novel KCNQ1 mutation in a family with Romano-Ward syndrome.

Romano-Ward syndrome (RWS), the autosomal dominant form of the congenital long QT syndrome, is characterised by prolongation of the cardiac repolarisation process associated with ventricular tachyarrhythmias of the torsades de pointes type. Genetic studies have identified mutations in six ion channel genes, KCNQ1, KCNH2, SCN5A, KCNE1 and KCNE2 and the accessory protein Ankyrin-B gene, to be responsible for this disorder. Single-strand conformation polymorphism (SSCP) analysis and subsequent DNA sequence analysis have identified a KCNQ1 mutation in a family that were clinically conspicuous due to several syncopes and prolonged QTc intervals in the ECG. The mutant subunit was expressed and functionally characterised in the Xenopus oocyte expression system. A novel heterozygous missense mutation with a C to T transition at the first position of codon 343 (CCA) of the KCNQ1 gene was identified in three concerned family members (QTc intervals: 500, 510 and 530 ms, respectively). As a result, proline 343 localised within the highly conserved transmembrane segment S6 of the KCNQ1 channel is replaced by a serine. Co-expression of mutant (KCNQ1-P343S) and wild-type (KCNQ1) cRNA in Xenopus oocytes produced potassium currents reduced by approximately 92%, while IKs reconstitution experiments with a combination of KCNQ1 mutant, wild-type and KCNE1 subunits yielded currents reduced by approximately 60%. A novel mutation (P343S) identified in the KCNQ1 subunit gene of three members of a RWS family showed a dominant-negative effect on native IKs currents leading to prolongation of the heart repolarisation and possibly increases the risk of malign arrhythmias with sudden cardiac death.

Amino Acid Sequence↗

Quantitative assessment of regional myocardial function in a rat model of myocardial infarction using tagged MRI.

We characterized global and regional left ventricular (LV) function during post myocardium infarction (MI) remodeling in rats, which has been incompletely described by previous MRI studies. To assess regional wall motion, four groups of infarcted animals corresponding to 1-2, 3-4, 6-8 and 9-12 weeks post-MI respectively were imaged using a fast gradient echo sequence with a 2D spatial modulation of magnetization (SPAMM) tagging preparation. An additional group was serially imaged (1-2 and 6-7 weeks post-MI) to assess the global function. Regional and global functional parameters of infarcted rats were compared to non-infarcted normal rats. Compared to normal rats, a decrease in ejection fraction (70 +/-7 vs. 40 +/- 8%, p<0.05) was observed in rats with MI. Maximal and minimal principal stretches (lambda1, lambda2) and strains (E1, E2), principal angle (beta) and displacement varied regionally in normal rats but deviated significantly from the normal values in rats with MI particularly in the infarcted and adjacent zones. Not only was strain magnitude reduced segmentally post-MI, but strain direction became more circumferentially oriented, particularly in rats with larger infarctions. We report the first regional myocardial strain values in normal and infarcted rats. These results parallel findings in humans, and provide a unique tool to examine regional mechanical influences on the remodeling process.

Algorithms↗

Impact of prior use or recent withdrawal of oral antiplatelet agents on acute coronary syndromes.

BACKGROUND: Oral antiplatelet agents (OAAs) can prevent further vascular events in cardiovascular disease. How prior use or recent discontinuation of OAA affects clinical presentation of acute coronary syndromes (ACS) and clinical outcomes (death, myocardial infarction [MI]) is unclear. METHODS AND RESULTS: We studied and followed up for up to 30 days a cohort of 1358 consecutive patients admitted for a suspected ACS; of these, 930 were nonusers, 355 were prior users of OAA, and 73 had recently withdrawn OAA. Nonusers were at lower risk, more frequently presented with ST-elevation MI on admission, and more frequently had Q-wave MI at discharge than prior users (36.6% versus 17.5%, P<0.001; and 47.8% versus 28.2%, P<0.001, respectively). However, there was no difference regarding the incidence of death or MI at 30 days between nonusers and prior users (10.3% versus 12.4%, P=NS). In addition, prior users experienced more major bleeds within 30 days compared with nonusers (3.4% versus 1.4%, respectively; P=0.04). Recent withdrawers were admitted on average 11.9+/-0.8 days after OAA withdrawal. Interruption was primarily a physician decision for scheduled surgery (n=47 of 73). Despite a similar cardiovascular risk profile, recent withdrawers had higher 30-day rates of death or MI (21.9% versus 12.4%, P=0.04) and bleedings (13.7% versus 5.9%, P=0.03) than prior users. After multivariate analysis, OAA withdrawal was found to be an independent predictor of both mortality and bleedings at 30 days. CONCLUSIONS: Among ACS patients, prior users represent a higher-risk population and present more frequently with non-ST-elevation ACS than nonusers. Although patients with a recent interruption of OAA resemble those chronically treated by OAA, they display worse clinical outcomes.

Acute Disease↗

Anti-Xa activity relates to survival and efficacy in unselected acute coronary syndrome patients treated with enoxaparin.

BACKGROUND: Low-molecular-weight heparin (LMWH) is recommended in the treatment of unstable angina (UA)/non-ST-segment-elevation myocardial infarction (NSTEMI), but no relationship has ever been shown between anticoagulation levels obtained with LMWH treatment and clinical outcomes. METHODS AND RESULTS: In all, 803 consecutive patients with UA/NSTEMI were treated with subcutaneous enoxaparin and were followed up for 30 days. The recommended dose of enoxaparin of 1 mg/kg BID was used throughout the population except when physicians decided on dose reduction because of a history of a recent bleeding event or because of a high bleeding risk. Anti-factor Xa activity was >0.5 IU/mL in 93% of patients; subtherapeutic anti-Xa levels (<0.5 IU/mL) were associated with lower doses of enoxaparin. The 30-day mortality rate was significantly associated with low anti-Xa levels (<0.5 IU/mL), with a >3-fold increase in mortality compared with the patients with anti-Xa levels in the target range of 0.5 to 1.2 IU/mL (P=0.004). Multivariate analysis revealed low anti-Xa activity as an independent predictor of 30-day mortality at least as strong as age, left ventricular function, and renal function. In contrast, anti-Xa activity did not predict major bleeding complications within the range of anti-Xa levels observed in this study. CONCLUSIONS: In this large unselected cohort of patients with UA/NSTEMI patients, low anti-Xa activity on enoxaparin treatment is independently associated with 30-day mortality, which highlights the need for achieving at least the minimum prescribed anti-Xa level of 0.5 IU/mL with enoxaparin whenever possible.

Aged↗

Prevention of disabling and fatal strokes by successful carotid endarterectomy in patients without recent neurological symptoms: randomised controlled trial.

BACKGROUND: Among patients with substantial carotid artery narrowing but no recent neurological symptom (stroke or transient ischaemia), the balance of surgical risks and long-term benefits from carotid endarterectomy (CEA) was unclear. METHODS: During 1993-2003, 3120 asymptomatic patients with substantial carotid narrowing were randomised equally between immediate CEA (half got CEA by 1 month, 88% by 1 year) and indefinite deferral of any CEA (only 4% per year got CEA) and were followed for up to 5 years (mean 3.4 years). Kaplan-Meier analyses of 5-year risks are by allocated treatment. FINDINGS: The risk of stroke or death within 30 days of CEA was 3.1% (95% CI 2.3-4.1). Comparing all patients allocated immediate CEA versus all allocated deferral, but excluding such perioperative events, the 5-year stroke risks were 3.8% versus 11% (gain 7.2% [95% CI 5.0-9.4], p<0.0001). This gain chiefly involved carotid territory ischaemic strokes (2.7% vs 9.5%; gain 6.8% [4.8-8.8], p<0.0001), of which half were disabling or fatal (1.6% vs 5.3%; gain 3.7% [2.1-5.2], p<0.0001), as were half the perioperative strokes. Combining the perioperative events and the non-perioperative strokes, net 5-year risks were 6.4% versus 11.8% for all strokes (net gain 5.4% [3.0-7.8], p<0.0001), 3.5% versus 6.1% for fatal or disabling strokes (net gain 2.5% [0.8-4.3], p=0.004), and 2.1% versus 4.2% just for fatal strokes (net gain 2.1% [0.6-3.6], p=0.006). Subgroup-specific analyses found no significant heterogeneity in the perioperative hazards or (apart from the importance of cholesterol) in the long-term postoperative benefits. These benefits were separately significant for males and females; for those with about 70%, 80%, and 90% carotid artery narrowing on ultrasound; and for those younger than 65 and 65-74 years of age (though not for older patients, half of whom die within 5 years from unrelated causes). Full compliance with allocation to immediate CEA or deferral would, in expectation, have produced slightly bigger differences in the numbers operated on, and hence in the net 5-year benefits. The 10-year benefits are not yet known. INTERPRETATION: In asymptomatic patients younger than 75 years of age with carotid diameter reduction about 70% or more on ultrasound (many of whom were on aspirin, antihypertensive, and, in recent years, statin therapy), immediate CEA halved the net 5-year stroke risk from about 12% to about 6% (including the 3% perioperative hazard). Half this 5-year benefit involved disabling or fatal strokes. But, outside trials, inappropriate selection of patients or poor surgery could obviate such benefits.

Aged↗

A lecturer's dilemma.

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Education, Dental, Continuing↗

Subcutaneous enoxaparin with early invasive strategy in patients with acute coronary syndromes.

BACKGROUND: Subcutaneous enoxaparin during at least 48 hours provides adequate anticoagulation and good clinical results in patients with non-ST-segment elevation acute coronary syndromes undergoing percutaneous coronary intervention (PCI). METHODS: In this nonrandomized retrospective study, we compared 347 patients with non-ST-segment elevation acute coronary syndromes who underwent rapid PCI after only 2 injections of subcutaneous enoxaparin (EI, n = 117) to those referred later to the catheterization laboratory with >or=3 injections (DI, n = 230). We measured anti-Xa at the time of PCI and evaluated bleeding and major ischemic events (death/myocardial infarction) at 30 days. RESULTS: Patients in the EI group more frequently received glycoprotein IIb/IIIa inhibitors and clopidogrel preceding PCI than did patients in the DI group (58.1% vs 31.7%, P <.0001 for glycoprotein IIb/IIIa inhibitors and 68.4% vs 40.4% for clopidogrel pretreatment, P <.0001, respectively). The anti-Xa activity measured at the time of catheterization (0.92 +/- 0.04 U/mL vs 0.96 +/- 0.02 U/mL, EI vs DI, P =.25) and the injection-to-catheterization times (5.6 +/- 0.2 h vs 5.2 +/- 0.1 h, EI vs DI, P =.17) were similar in both groups. The 30-day bleeding rates of 1.7% and 4.8% in the EI and DI strategies were found to be equivalent with a significant non-inferiority test for the EI strategy (P <.05). There was a nonsignificant trend for less death or myocardial infarction at 30 days in the EI group compared to the DI group (4.3% vs 7.0%, non-inferiority test not significant). CONCLUSION: A rapid invasive strategy with only 2 subcutaneous injections of enoxaparin provides similar levels of anticoagulation, and is associated with a favorable trend for ischemic events and with safety equivalent to a more prolonged "upstream" treatment with enoxaparin.

Analysis of Variance↗