POS0514 PREDICTION OF RESPONSE TO METHOTREXATE IN PATIENTS WITH RHEUMATOID ARTHRITIS: A MACHINE LEARNING APPROACH USING CLINICAL TRIAL DATA

Background

Methotrexate (MTX) is the preferred initial disease-modifying drug (DMARD) for rheumatoid arthritis (RA). However, up to 50% of patients respond inadequately to MTX (1). Clinically useful predictors that effectively identify patients with RA who are likely to respond to MTX are lacking. Whether machine learning (ML) can provide robust and clinically useful prediction of response to MTX monotherapy in the first months of treatment in patients with early RA using uniformly collected baseline demographics and clinical data has not been investigated in large patient populations.

Objectives

We aimed to identify clinical predictors of response to MTX as the first DMARD among patients with RA using ML methods.

Methods

Randomized clinical trials (RCT) of patients with RA who were DMARD-naïve and randomized to placebo plus MTX were identified and accessed through the Clinical Study Data Request Consortium and Vivli Center for Global Clinical Research Data. Studies with available Disease Activity Score with 28-joint count and erythrocyte sedimentation rate (DAS28-ESR) at baseline, 12 and 24 weeks were included. Latent class modeling of MTX response was performed. Least absolute shrinkage and selection operator (LASSO) and random forest were used to identify predictors of response.

Results

A total of 775 patients from 4 RCTs were included (mean age 50 years, 80% female). Two distinct classes of patients were identified based on DAS28-ESR change over 24 weeks: “good responders” and “poor responders” to MTX treatment (Figure 1). Baseline DAS28-ESR, anti-citrullinated protein antibody (ACPA) and health assessment questionnaire (HAQ) score were the top predictors of good response to MTX using LASSO (Area Under the Curve [AUC] 0.79) and Random Forest models (AUC 0.68) in the external validation set. DAS28-ESR≤7.4, ACPA positive and HAQ≤2 provided the highest likelihood of response (Table 1). Among patients with 12-week DAS28-ESR>3.2, at least 1 point improvement in DAS28-ESR baseline-to-12-week was predictive of achieving DAS28-ESR≤3.2 at 24 weeks.

Table 1.

Matrix prediction model: Probability of achieving a good response to methotrexate at 24 weeks

DAS28ESR≤7.480.1 (76.4, 83.8)77.3 (70.6, 84)PositiveACPA Status77.1 (68.6, 85.6)74.1 (63.3, 84.9)Negative>7.440.3 (32.1, 48.5)36.5 (29.3, 43.6)Positive36.2 (23.3, 49.1)32.5 (20.9, 44.1)Negative≤2>2HAQ

Footnote: The number in each cell represents the percentage and 95% CI of achieving the outcome, based on the combination of predictors at baseline. DAS28-ESR: Disease Activity Score with 28-joint count with erythrocyte sedimentation rate; HAQ: Health assessment questionnaire score; ACPA: Anti-citrullinated protein antibody.

Figure 1.

Two patient class trajectories identified with latent class modeling of DAS28-ESR (N=775)

Conclusion

We have developed and externally validated a prediction model for response to MTX within 24 weeks in DMARD-naïve patients with RA, providing variably weighted clinical features and defined cut-offs for clinical decision-making. Trajectory of DAS28-ESR change over 24 weeks in patients with moderate-to-high RA disease activity at baseline who are starting MTX can be predicted by baseline DAS28-ESR, ACPA status and HAQ-score. Patients with at least 1 unit decline in DAS28-ESR within the first 12 weeks of treatment who have not achieved low disease activity by week 12, may be more likely to achieve low disease activity at 24 weeks. These parameters should be considered as part of the clinical decision-making process when initiating MTX in DMARD-naïve patients with RA.

References

[1]Aletaha D, Smolen JS. Effectiveness profiles and dose dependent retention of traditional disease modifying antirheumatic drugs for rheumatoid arthritis. An observational study. J Rheumatol. 2002;29(8):1631-8.

Acknowledgements

This abstract is based on research using data from data contributors UCB and Roche that has been made available through Vivli, Inc. Vivli has not contributed to or approved, and is not in any way responsible for, the contents of this publication.

Disclosure of Interests

Stephanie Duong: None declared, Cynthia S. Crowson: None declared, Arjun Athreya: None declared, Elizabeth Atkinson: None declared, John M Davis III Grant/research support from: Pfizer, Kenneth J Warrington Speakers bureau: Chemocentryx, Consultant of: Roche/Genentech, Eric Matteson: None declared, Richard Weinshilboum Shareholder of: OneOme, Liewei Wang Shareholder of: OneOme, Elena Myasoedova: None declared.

Macrophages Mediate the Antitumor Effects of the Oncolytic Virus HSV1716 in Mammary Tumors

Oncolytic viruses (OV) have been shown to activate the antitumor functions of specific immune cells like T cells. Here, we show OV can also reprogram tumor-associated macrophage (TAM) to a less immunosuppressive phenotype. Syngeneic, immunocompetent mouse models of primary breast cancer were established using PyMT-TS1, 4T1, and E0771 cell lines, and a metastatic model of breast cancer was established using the 4T1 cell line. Tumor growth and overall survival was assessed following intravenous administration of the OV, HSV1716 (a modified herpes simplex virus). Infiltration and function of various immune effector cells was assessed by NanoString, flow cytometry of dispersed tumors, and immunofluorescence analysis of tumor sections. HSV1716 administration led to marked tumor shrinkage in primary mammary tumors and a decrease in metastases. This was associated with a significant increase in the recruitment/activation of cytotoxic T cells, a reduction in the presence of regulatory T cells and the reprograming of TAMs towards a pro-inflammatory, less immunosuppressive phenotype. These findings were supported by in vitro data demonstrating that human monocyte-derived macrophages host HSV1716 replication, and that this led to immunogenic macrophage lysis. These events were dependent on macrophage expression of proliferating cell nuclear antigen (PCNA). Finally, the antitumor effect of OV was markedly diminished when TAMs were depleted using clodronate liposomes. Together, our results show that TAMs play an essential role in support of the tumoricidal effect of the OV, HSV1716-they both host viral replication via a novel, PCNA-dependent mechanism and are reprogramed to express a less immunosuppressive phenotype.

A case-control study of childhood trauma in the development of irritable bowel syndrome

BACKGROUND

The etiology of irritable bowel syndrome (IBS) is not been fully elucidated, but childhood trauma may disturb the brain-gut axis and therefore be important. Thus, we conducted a family based case-control study of IBS cases and their relatives with the aims to (i) determine the frequency of childhood trauma among IBS cases and controls as well as their relatives, and (ii) assess childhood trauma among IBS cases with affected relatives (familial IBS).

METHODS

Outpatients with IBS, matched controls, and their first-degree relatives completed a self-report version of Bremner' Early Trauma Inventory. Percent of cases and controls with a family history were compared and odds ratios were computed using chi-squared test; recurrence risks to relatives were computed using logistic regression and generalized estimating equations.

KEY RESULTS

Data were collected from 409 cases, 415 controls, 825 case relatives, and 921 control relatives. IBS cases had a median age of 50 and 83% were women. Of IBS cases, 74% had experienced any general trauma compared to 59% among controls, yielding an odds ratio of 1.56 (95% CI: 1.13-2.15, p < 0.008). There were no statistical differences between IBS relatives and control relatives with regards to lifetime trauma.

CONCLUSIONS & INFERENCES

IBS is associated with childhood trauma, and these traumas often occur prior to onset of IBS symptoms. This provides further insight into how traumatic childhood events are associated with development of adult IBS.

Variation of fluorescence spectroscopy during the menstrual cycle

Cervical autofluorescence has been demonstrated to have potential for real-time diagnosis. Inter-patient and intra-patient variations in fluorescence intensity have been measured. Inter-patient measurements may vary by a factor of ten, while intra-patient measurements may vary by a factor of two. Age and menopausal status have been demonstrated to account for some of the variations, while race and smoking have not. In order to explore in detail the role of the menstrual cycle in intra-patient variation, a study was designed to measure fluorescence excitation emission matrices (EEMs) in patients daily throughout one cycle. Ten patients with a history of normal menstrual cycles and normal Papanicolaou smears underwent daily measurements of fluorescence EEMs from three colposcopically normal sites throughout one menstrual cycle. Changes in signals from porphyrin, NADH, and FAD fluorescence and blood absorption were noted when the data was viewed in a graphical format. Visually interpreted features of the EEMs in this graphical format did not appear to correlate with the day of the menstrual cycle with the exception that blood absorption features were more prominent during the menstrual phase (during which bleeding occurs), suggesting that measurements during the menstrual phase should be avoided. Variations in cycle date likely do not account for inter- or intra-patient variations.

Genetic variation in the transforming growth factor beta1 gene in multiple sclerosis

Transforming growth factor beta1 (TGFbeta1) is a Th2 cytokine encoded on chromosome 19q13, a region possibly linked to multiple sclerosis (MS). TGFbeta1 exerts favorable effects on experimental allergic encephalomyelitis. We performed a comprehensive search for genetic variants in this gene in 122 population-based sporadic cases of MS. We detected six variants, including three missense variants. We tested for association of the variants with susceptibility and course of MS and for linkage and transmission disequilibrium in a family series consisting of 395 samples in 59 pedigrees. Genetic variation in TGFB1 does not appear to contribute in a major way to susceptibility to MS.

Influence of tacrolimus and prednisone on serum lipids after liver transplantation

BACKGROUND

Hyperlipidemia after orthotopic liver transplant is thought to be the result of the immunosuppression therapy given postoperatively. The purpose of this study was to evaluate serum lipid levels pretransplant, 4 months, and 12 months posttransplant.

METHODS

A retrospective chart review of 50 patients after liver transplantation was completed. Pretransplant serum lipid levels (triglyceride, cholesterol, and high-density lipoprotein [HDL]) were compared with values at 4 months and 12 months posttransplantation. Pretransplant serum lipid levels were compared using one factor analysis of variance (ANOVA) model. Values between the viral, alcohol, and cholestatic groups were compared using two-factor ANOVA model.

RESULTS

Of the 50 patients (22 females, 28 males) with a mean age of 52 years (range, 16 to 69 years), all 50 had completed their 12-month follow-up at the time of this study. The etiology of liver disease included: viral hepatitis (21), alcohol (8), primary biliary cirrhosis and sclerosing cholangitis (7), and others (14). The protocol for immunosuppression included tacrolimus and prednisone. Mean serum triglyceride levels included: 134 mg/dL pretransplant, 155 mg/dL at 4 months, and 169 mg/dL at 12 months posttransplant (p = .117). Mean total serum cholesterol levels included: 174 mg/dL pretransplant, 165 mg/dL at 4 months, and 163 mg/dL at 12 months posttransplant (p = .654). Mean HDL levels included: 39 mg/dL pretransplant, 45 mg/dL at 4 months and 44 mg/dL at 12 months posttransplant (p = .032). There was not a significant difference in serum lipids between the different categories of liver diseases.

CONCLUSIONS

Although a significant positive effect was observed with HDL, the present data show that total serum cholesterol and triglyceride did not change significantly over time after orthotopic transplantation. This is most likely related to the type of immunosuppressive therapy given posthepatic transplantation.

Distal mucocolpos and proximal hematocolpos secondary to concurrent imperforate hymen and transverse vaginal septum

A 12-year-old girl had cruciate incision of imperforate hymen draining a large mucocolpos. Her symptoms did not abate thereafter, and 3 months later a transverse vaginal septum was diagnosed. This was perforated and dilated under ultrasound (US) guidance draining a large hematocolpos. Results of examination under anesthesia after 3 months was satisfactory, and she has had normal periods in follow-up for 9 months. Imperforate hymen and transverse vaginal septum are known causes of mucocolpos and hematocolpos. However, the concurrent occurrence of the two abnormalities is unique.

Genetic variants in the tumor necrosis factor receptor 1 gene in patients with MS

We scanned for all genetic variants in functionally important regions of the tumor necrosis factor receptor 1 gene (TNF-R1) in 100 to 111 MS patients from Olmsted County, MN, and analyzed selected variants for an association with disease course and severity. Ten genetic variants were uncovered. Only one variant, a silent substitution, was found in coding sequence. One intronic variant may generate a novel splice-junction sequence. We did not find an association between either this intronic variant or another common promoter variant and the course or severity of MS.

Expression of stromelysin-3 in atherosclerotic lesions: regulation via CD40-CD40 ligand signaling in vitro and in vivo

Stromelysin-3 is an unusual matrix metalloproteinase, being released in the active rather than zymogen form and having a distinct substrate specificity, targeting serine proteinase inhibitors (serpins), which regulate cellular functions involved in atherosclerosis. We report here that human atherosclerotic plaques (n = 7) express stromelysin-3 in situ, whereas fatty streaks (n = 5) and normal arterial specimens (n = 5) contain little or no stromelysin-3. Stromelysin-3 mRNA and protein colocalized with endothelial cells, smooth muscle cells, and macrophages within the lesion. In vitro, usual inducers of matrix metalloproteinases such as interleukin-1, interferon-gamma, or tumor necrosis factor alpha did not augment stromelysin-3 in vascular wall cells. However, T cell-derived as well as recombinant CD40 ligand (CD40L, CD154), an inflammatory mediator recently localized in atheroma, induced de novo synthesis of stromelysin-3. In addition, stromelysin-3 mRNA and protein colocalized with CD40L and CD40 within atheroma. In accordance with the in situ and in vitro data obtained with human material, interruption of the CD40-CD40L signaling pathway in low density lipoprotein receptor-deficient hyperlipidemic mice substantially decreased expression of the enzyme within atherosclerotic plaques. These observations establish the expression of the unusual matrix metalloproteinase stromelysin-3 in human atherosclerotic lesions and implicate CD40-CD40L signaling in its regulation, thus providing a possible new pathway that triggers complications within atherosclerotic lesions.

Interobserver reproducibility of the Lagios nuclear grading system for ductal carcinoma in situ

Several studies have shown an association between high nuclear grade or necrosis of ductal carcinoma in situ (DCIS) lesions and the risk of local disease recurrence in patients with DCIS treated surgically with less than mastectomy. Although criteria for separating low from high nuclear grade lesions have been published, no information exists regarding interobserver reproducibility (IR). To assess IR in the classification of DCIS, six surgical pathologists from four institutions used the Lagios grading system to grade 125 DCIS lesions. Before meeting to evaluate the cases, a training set of 12 glass slides, including cases chosen to present conflicting cues for classification, was mailed to the participants with a written criteria summary. This was followed by a working session in which criteria were reviewed and agreed on. The pathologists then graded the lesions independently. The area of interest was marked on each slide before grading. After initial grading, the pathologists met again to resolve discrepant lesion classifications. A complete agreement among raters was achieved in 43 (35%) cases, with five of six raters agreeing in another 45 (36%) cases. In no case did two raters differ by more than one grade. The pairwise kappa agreement values ranged from fair to substantial (0.30 to 0.61). Generalized kappa value indicated moderate agreement (0.46, standard error = 0.02). Kappa statistics for the distinction between grades 1 and 2 and 2 and 3 were 0.29 and 0.48, respectively, (standard error = 0.02). Only one of the six raters differed significantly in scoring. With adherence to specific criteria, IR in the classification of DCIS cases can be obtained in most cases. Although these pathologists made a few grading system modifications, further refinements are needed, especially if grading will influence future therapy.

T lymphocytes induce endothelial cell matrix metalloproteinase expression by a CD40L-dependent mechanism: implications for tubule formation

Neovascularization frequently accompanies chronic immune responses characterized by T cell infiltration and activation. Angiogenesis requires endothelial cells (ECs) to penetrate extracellular matrix, a process that involves matrix metalloproteinases (MMPs). We report here that activated human T cells mediate contact-dependent expression of MMPs in ECs through CD40/CD40 ligand signaling. Ligation of CD40 on ECs induced de novo expression of gelatinase B (MMP-9), increased interstitial collagenase (MMP-1) and stromelysin (MMP-3), and activated gelatinase A (MMP-2). Recombinant human CD40L induced expression of MMPs by human vascular ECs to a greater extent than did maximally effective concentrations of interleukin-1beta or tumor necrosis factor-alpha. Moreover, activation of human vascular ECs through CD40 induced tube formation in a three-dimensional fibrin matrix gel assay, an effect antagonized by a MMP inhibitor. These results demonstrated that activation of ECs by interaction with T cells induced synthesis and release of MMPs and promoted an angiogenic function of ECs via CD40L-CD40 signaling. As vascular cells at the sites of chronic inflammation, such as atherosclerotic plaques, express CD40 and its ligand, our findings suggest that ligation of CD40 on ECs can mediate aspects of vascular remodeling and neovessel formation during atherogenesis and other chronic immune reactions.

Reduction of atherosclerosis in mice by inhibition of CD40 signalling

Increasing amounts of evidence support the involvement of inflammation and immunity in atherogenesis, but mediators of communication between the major cell types in atherosclerotic plaques are poorly defined. Cells in human atherosclerotic lesions express the immune mediator CD40 and its ligand CD40L (also known as CD154 or gp39). The interaction of CD40 with CD40L figures prominently in both humoral and cell-mediated immune responses. CD40L-positive T cells accumulate in atheroma, and, by virtue of their early appearance, persistence and localization at sites of lesion growth and complication, activated T cells may coordinate important aspects of atherogenesis. Interruption of CD40L-CD40 signalling by administration of an anti-CD40L antibody limits experimental autoimmune diseases such as collagen-induced arthritis, lupus nephritis, acute or chronic graft-versus-host disease, multiple sclerosis and thyroiditis. Ligation of CD40 on atheroma-associated cells in vitro activates functions related to atherogenesis, including induction of proinflammatory cytokines, matrix metalloproteinases, adhesion molecules and tissue factor. However, the role of CD40 signalling in atherogenesis in vivo remains unknown. Here we determine whether interruption of CD40 signalling influences atherogenesis in vivo in hyperlipidaemic mice. Treatment with antibody against mouse CD40L limited atherosclerosis in mice lacking the receptor for low-density lipoprotein that had been fed a high-cholesterol diet for 12 weeks. This antibody reduces the size of aortic atherosclerotic lesions by 59% and their lipid content by 79%. Furthermore, atheroma of mice treated with anti-CD40L antibody contained significantly fewer macrophages (64%) and T lymphocytes (70%), and exhibited decreased expression of vascular cell adhesion molecule-1. These data support the involvement of inflammatory pathways in atherosclerosis and indicate a role for CD40 signalling during atherogenesis in hyperlipidaemic mice.

Relative contributions of incidence and survival to increasing prevalence of adult-onset diabetes mellitus: a population-based study

This population-based retrospective study investigates temporal trends in adult-onset diabetes mellitus prevalence, incidence, and survival. The complete community-based medical records, including laboratory results, of all Rochester, Minnesota, residents with a clinical diagnosis of diabetes or diabetes-like condition were reviewed to identify incidence cases aged 30 years or more from 1945 to 1989 (n = 1,847) and prevalence cases aged 45 years or more on January 1, 1970 (n = 465), January 1, 1980 (n = 689), or January 1, 1990 (n = 973). Glucose values and case definitions were standardized throughout. Observed 10-year survival for 1970 and 1980 prevalence cases was compared with that expected for Minnesota white populations in 1970 and 1980, respectively. Age-adjusted prevalence rose 65% for men and 37% for women between 1970 and 1990. There were marked differences among prevalence groups in treatment type, the proportion diagnosed using glucose tolerance tests, and the proportion categorized as obese. Relative survival for 1980 prevalence cases was not greater than that for 1970 prevalence cases. Age-adjusted incidence rates rose 47% for men and 26% for women between 1960 and 1965 and 1985 and 1989. These findings emphasize the need for heightened surveillance and intervention to reduce the burden of illness from adult-onset diabetes mellitus in the population.

Identification of a serpin specifically expressed in multipotent and bipotent hematopoietic progenitor cells and in activated T cells

We have identified a gene that has a high level of mRNA expression in undifferentiated, multipotential hematopoietic cells (FDCP-Mix) and that downregulates both transcript and protein, as these cells are induced to differentiate into mature myeloid cells. Sequence analysis of this gene has identified it as a serine protease inhibitor EB22/3 (serpin 2A). Constitutive expression of serpin 2A in FDCP-Mix cells was associated with an increase in the clonogenic potential of the cells and with a delay in the appearance of fully mature cells in cultures undergoing granulocyte macrophage differentiation when compared with control cells. Serpin 2A was also found to be expressed in bone marrow-derived bipotent granulocyte macrophage progenitor cells (GM-colony forming cell [CFC]), but not in erythrocyte progenitor cells from day 15 fetal liver. Expression of serpin 2A also showed a marked up regulation during the activation of cytotoxic suppressor CD8+ T cells, with a clear lag between the appearance of transcript and detection of protein.

Sleep disruption in young children. The influence of temperament on the sleep patterns of pre-school children

Sleep problems are a common concern of parents with toddlers. Various reasons have been put forward as to the possible causes and maintenance of sleep disruption. These have included neurophysical differences in the child, perinatal differences such as a long labour and depression and anxiety in the parents themselves resulting in adverse effects on the child's sleep patterns. However, recent research has indicated that a child's temperamental style may be a possible causal factor as to whether the child will present its parents with a sleep problem. This study, therefore, sets out to investigate the importance of temperament as a predictor of whether children may or may not have sleep problems. Environmental factors are controlled as far as possible by selecting toddlers with and without sleep problems from very similar environments. Case studies are also introduced to further illuminate other possible associated factors such as parental handling. The results from this study found significant differences in the temperament profiles of children with and without sleep problems. Children with reported sleep problems were more likely to obtain a 'intermediate high to difficult' profile. Various findings from a group of toddlers with and without sleep problems are discussed in this paper together with implications of the findings and recommendations for further research.

Acceptance and perceptions of NORPLANT among users in San Francisco, USA

Two hundred and five women participating in a five-year clinical trial of NORPLANT and NORPLANT-2 were interviewed about their contraceptive and reproductive history, sources of information and knowledge of NORPLANT, experiences using the method, and the impressions of friends and family about the method. The most common reasons for trying the implants were dissatisfaction with other methods and perceptions about NORPLANT's ease of use. Forty-one percent of acceptors had anxiety prior to insertion; 49 percent of these feared pain, but only 5 percent said that they actually experienced significant pain. Women also feared implant removal, but their fear did not influence their decision to continue or discontinue use, and 74 percent reported little or no pain at removal. Most of the women were pleased with NORPLANT, although 95 percent reported side effects, with 82 percent reporting changes in menstruation. More than one-half of those women who discontinued reported that they would use the implants again. Seventy-four percent of the current users interviewed said they would like to use the implants in the future. For the women enrolled in the clinical trial, NORPLANT appeared to be a highly acceptable method of contraception, despite the frequent occurrence of bothersome side effects.

Uterine perforation during second-trimester abortion by cervical dilation and instrumental extraction: a review of 15 cases

Review of the records of 15 women who had uterine perforations at the time of second-trimester abortion by dilation and evacuation showed that unexpected pain (but not excessive bleeding) was the most prominent sign. All patients required laparotomy, but in no case was laparotomy necessary as an emergency procedure. Laparoscopy was not helpful. Two-thirds had bowel injuries and two required hysterectomy. Errors in estimating gestational duration, inadequate cervical dilation, and failure to use sonography characterized these complicated cases.

Modulation of experimental retinal vasculitis using dexamethasone, cyclosporin A, and prazosin

The effects of dexamethasone, cyclosporin A and prazosin were investigated in an animal model of retinal vasculitis. Both dexamethasone and cyclosporin A reduced the clinical and pathological signs of disease when given from the day of disease onset. Prazosin, an alpha 1 adrenergic antagonist, was given during the period of disease induction and blocked fluorescein leakage from actively inflamed retinal vessels, but had little effect on the clinical and pathological signs of disease. This study demonstrates the feasibility of using this animal model for therapeutic trials of anti-inflammatory agents in retinal vasculitis. The effect of prazosin on reducing vascular leakage from retinal vessels has implications for the treatment of inflammatory macula oedema in human disease.

Solvent influence on model oxidations of alpha-tocopherol

(+/-)-alpha-Tocopherol has been oxidised with t-butyl hydroperoxide in chloroform in order to simulate in vivo oxidations due to lipid hydroperoxides. t-Butyl hydroperoxide proved to be a weak oxidant and failed to oxidise alpha-tocopherol in 3 h at 60 degrees C. Inclusion of a small amount of ethanol in the reaction mixture brought about immediate oxidation and the formation of a new product, 5-ethoxymethyl-7,8-dimethyltocol in addition to the spiro dimer and spiro trimer of alpha-tocopherol, alpha-tocopherylquinone and 5-formyl-7,8-dimethyltocol. Formation of 5-ethoxymethyl-7,8-dimethyltocol increased with increasing concentrations of ethanol, up to a maximum of 59% at 20% ethanol. Further increase in ethanol concentration brought about a decrease in the oxidation of alpha-tocopherol and in the formation of 5-ethoxymethyl-7,8-dimethyltocol. Oxidation of the tocopherol model compound 2,2,5,7,8-pentamethyl-6-hydroxychroman under similar conditions produced the analogous product, 5-ethoxymethyl-2,2,7,8-tetramethyl-6-hydroxychroman together with 5-formyl-2,2,7,8-tetramethyl-6-hydroxychroman and 2-(3'-hydroxy-3'-methylbutyl)-3,5,6-trimethylbenzo-1,4-quinone.

Some Points of Osteology of the Pichiciégo

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