Evaluating the Disease-Related Experiences of TikTok Users With Lupus Erythematosus: Qualitative and Content Analysis

BACKGROUND

Lupus erythematosus (LE) is an autoimmune condition that is associated with significant detriments to quality of life and daily functioning. TikTok, a popular social networking platform for sharing short videos, provides a unique opportunity to understand experiences with LE within a nonclinical sample, a population that is understudied in LE research. This is the first qualitative study that explores LE experiences using the TikTok platform.

OBJECTIVE

This study aims to evaluate the disease-related experiences of TikTok users with LE using qualitative and content analysis.

METHODS

TikTok videos were included if the hashtags included #lupus, were downloadable, were in English, and involved the personal experience of an individual with LE. A codebook was developed using a standardized inductive approach of iterative coding until saturation was reached. NVivo (Lumivero), a qualitative analysis software platform, was used to code videos and perform content analysis. Inductive thematic analysis was used to derive themes from the data.

RESULTS

A total of 153 TikTok videos met the inclusion criteria. The most common codes were experiences with symptoms (106/153, 69.3%), mucocutaneous symptoms (61/153, 39.9%), and experiences with treatment (59/153, 38.6%). Experiences with symptoms and mucocutaneous symptoms had the greatest cumulative views (25,381,074 and 14,879,109 views, respectively). Five thematic conclusions were derived from the data: (1) mucocutaneous symptoms had profound effects on the mental health and body image of TikTok users with LE; (2) TikTok users' negative experiences with health care workers were often derived from diagnostic delays and perceptions of "medical gaslighting"; (3) TikTok users tended to portray pharmacologic and nonpharmacologic interventions, such as diet and naturopathic remedies, positively, whereas pharmacologic treatments were portrayed negatively or referred to as "chemotherapy"; (4) LE symptoms, particularly musculoskeletal symptoms and fatigue, interfered with users' daily functioning; and (5) although TikTok users frequently had strong support systems, feelings of isolation were often attributed to battling an "invisible illness."

CONCLUSIONS

This study demonstrates that social media can provide important, clinically relevant information for health practitioners caring for patients with chronic conditions such as LE. As mucocutaneous symptoms were the predominant drivers of distress in our sample, the treatment of hair loss and rash is vital in this population. However, pharmacologic therapies were often depicted negatively, reinforcing the significance of discussions on the safety and effectiveness of these treatments. In addition, while TikTok users demonstrated robust support systems, feelings of having an "invisible illness" and "medical gaslighting" dominated negative interactions with others. This underscores the importance of providing validation in clinical interactions.

Autoimmune bullous disorder flares following severe acute respiratory syndrome coronavirus 2 vaccination: a case series

BACKGROUND

Autoimmune bullous disorders develop due to autoantibodies targeting intercellular adhesion proteins of hemidesmosomes and desmosomes and may be triggered by viral infections and vaccines. Recent reports suggest that the coronavirus disease 2019 vaccination may trigger flares or exacerbations of preexisting autoimmune diseases, including new onset autoimmune bullous disorders. There are less data on whether vaccination against severe acute respiratory syndrome coronavirus 2 may also exacerbate preexisting autoimmune bullous disorders.

CASE PRESENTATION

Here we present three cases, two white males (ages 69 years and 88 years) with bullous pemphigoid and one white 50-year-old female with pemphigus foliaceus, wherein all individuals developed minor, tractable flares of their preexisting autoimmune bullous disorders after receiving the coronavirus disease 2019 vaccination, which were readily treatable with topical or low-dose systemic corticosteroids.

CONCLUSIONS

Dermatologists managing patients with autoimmune bullous disorders should be cognizant of the uncommon potential for flares of the disorder following vaccination for severe acute respiratory syndrome coronavirus 2. Flares of bullous pemphigoid and pemphigus foliaceus following vaccination for severe acute respiratory syndrome coronavirus 2 in these cases were mild and tractable.

3D Printed Skin-Interfaced UV-Visible Hybrid Photodetectors

Photodetectors that are intimately interfaced with human skin and measure real-time optical irradiance are appealing in the medical profiling of photosensitive diseases. Developing compliant devices for this purpose requires the fabrication of photodetectors with ultraviolet (UV)-enhanced broadband photoresponse and high mechanical flexibility, to ensure precise irradiance measurements across the spectral band critical to dermatological health when directly applied onto curved skin surfaces. Here, a fully 3D printed flexible UV-visible photodetector array is reported that incorporates a hybrid organic-inorganic material system and is integrated with a custom-built portable console to continuously monitor broadband irradiance in-situ. The active materials are formulated by doping polymeric photoactive materials with zinc oxide nanoparticles in order to improve the UV photoresponse and trigger a photomultiplication (PM) effect. The ability of a stand-alone skin-interfaced light intensity monitoring system to detect natural irradiance within the wavelength range of 310-650 nm for nearly 24 h is demonstrated.

Patient Quality of Life Improvement in Bullous Disease: A Review of Primary Literature and Considerations for the Clinician

Autoimmune and inherited bullous disorders are rare skin diseases that may have a profound negative impact on quality of life (QOL). Common symptoms include pain, pruritus, and scarring, and complications may result in the loss of the ability to perform daily tasks. Diagnosis may have a negative psychological impact, and ongoing management may require a significant allocation of time and resources by both patients and providers. To provide patient-centered care, consideration of these factors is of utmost importance for the dermatologist treating patients with bullous disorders. Herein, we present a review of the primary literature evaluating QOL in autoimmune and inherited bullous disorders, including pemphigus, pemphigoid, epidermolysis bullosa, and Hailey-Hailey disease.

A case of VEXAS syndrome associated with EBV-associated hemophagocytic lymphohistiocytosis

Vacuoles, E1, X-linked, autoimmunity, somatic (VEXAS) syndrome is characterized by a pathogenic mutation in UBA1, which leads to protean complications including autoimmunity and myelodysplasia. A 56-year-old man with steroid-dependent, later steroid-refractory cutaneous polyarteritis nodosa and Sweet syndrome developed recurrent daily fever, macrocytic anemia, thrombocytopenia, acute hypoxic respiratory failure, and anasarca. He was eventually diagnosed with Epstein-Barr virus (EBV) viremia and hemophagocytic lymphohistiocytosis (HLH). He improved clinically with rituximab, ruxolitinib, and increased glucocorticoids before expiring from Pseudomonas sepsis. UBA1 exon 3 mutational analysis in myeloid enriched peripheral blood revealed a c.122T>C (p.Met41Thr) pathogenic variant, consistent with VEXAS syndrome. We describe the first case of EBV-associated HLH in a patient diagnosed with VEXAS syndrome. Early identification of this syndrome will be important in order to offer potential therapies before life-threatening complications arise.

Malignancy in dermatomyositis: A retrospective study of 201 patients seen at the University of Pennsylvania

BACKGROUND

There is an increased incidence of malignancy in patients with dermatomyositis. It is unknown if the risk differs between the subtypes of dermatomyositis.

OBJECTIVE

To (1) compare the prevalence of malignancy-associated dermatomyositis between patients with classic and clinically amyopathic disease and (2) determine factors associated with an increased risk of malignancy-associated disease.

METHODS

Retrospective cohort study of 201 patients with adult-onset dermatomyositis prospectively enrolled in a longitudinal dermatomyositis database between July 2008 and April 2018 at an outpatient dermatology urban tertiary referral center. The main outcome measure was a diagnosis of malignancy, excluding nonmelanoma skin cancer.

RESULTS

There were 201 patients with adult-onset dermatomyositis: 142 (71%) classic and 59 (29%) clinically amyopathic. Within 2 years of diagnosis, the prevalences of malignancy-associated classic and clinically amyopathic dermatomyositis were 9.9% and 1.7%, respectively. In this time period, patients who were older at dermatomyositis diagnosis (P = .01) and had the classic subtype (P = .04) were significantly more likely to have an underlying malignancy on multivariable regression analysis.

LIMITATIONS

This was a retrospective study of prospectively collected data at a single tertiary referral center.

CONCLUSION

Older age and classic dermatomyositis are independent risk factors for malignancy-associated dermatomyositis within 2 years of disease onset.

Remote-onset alopecia areata attributed to ipilimumab

Ipilimumab is a fully humanized monoclonal antibody against cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and one of a growing class of immunomodulatory therapies for melanoma. The most common toxicities are immune-related adverse effects (irAEs), which manifest most frequently in the skin as rash and pruritus. We report a case of alopecia areata (AA) attributed to ipilimumab that presented 1.5 years after treatment. Because CTLA-4 dysregulation has been increasingly linked to AA, the incidence of this irAE may increase following US Food and Drug Administration approval of a higher dose of ipilimumab for adjuvant treatment of stage III melanoma.

Assessing the Correlation Between Disease Severity Indices and Quality of Life Measurement Tools in Pemphigus

Pemphigus, an autoimmune blistering disease that affects the skin and mucous membranes, adversely impacts patients' quality of life (QOL). While there are various QOL measurement tools that can be used in this disease, few studies have assessed how a patient's change in disease severity can affect their QOL. This study aims to identify which disease severity index correlates best with the change in QOL. Fifty pemphigus patients completed QOL surveys with disease severity scored over two visits. QOL was assessed with the Autoimmune Bullous Disease Quality of Life (ABQOL), Dermatology Life Quality Index (DLQI), Skindex-29, and Short Form Survey 36 (SF-36). Disease severity was scored with the Pemphigus Disease Area Index (PDAI) and Autoimmune Bullous Skin Disorder Intensity Score (ABSIS). Correlations between the change in QOL scores and change in disease severity were analyzed using Spearman's coefficient (r). The change in PDAI showed a strong correlation (r = 0.60–0.79) with changes in the ABQOL, Skindex-29 symptoms (Skindex-S), and Skindex-29 functioning (Skindex-F) subscales for all patients (n = 50). For patients with mucosal disease (n = 24), the change in PDAI showed a strong correlation with changes in the ABQOL and Skindex-S subscale. For patients without mucosal disease, the change in PDAI showed a strong correlation with the Skindex-S. The change in ABSIS showed a strong correlation with Skindex-S for all patients and patients with no mucosal involvement, but showed no strong correlations for patients with mucosal involvement. The changes in PDAI always had a stronger correlation than the changes in ABSIS scores to changes in the ABQOL, DLQI, and Skindex-29 subscales, except where the PDAI and ABSIS scores were about the same for the Skindex-S subscale in patients with no mucosal involvement (r = 0.76 and r = 0.77, respectively). PDAI is superior to ABSIS in its correlation with validated QOL tools. The QOL tools that appear to be of most use in clinical trials and patient management are the Skindex-S and ABQOL.

Dermatomyositis in patients with autoimmune blistering diseases

It is common for multiple autoimmune diseases to occur in the same patient. However, autoimmune blistering diseases (AIBD) do not commonly associate with dermatomyositis (DM). We performed a literature review and found 12 previous reports that may be attributed to misdiagnosis, underreporting, or true rarity of association. Herein, we present a case of pemphigus vulgaris and a case of mucous membrane pemphigoid associated with DM and review the related literature. AIBD-associated interstitial lung disease, genetic predisposition, potential environmental triggers of both AIBD and DM, drug-related triggers, and paraneoplastic processes are discussed. Dermatologists must be vigilant for a second autoimmune disease in patients with AIBD that may have therapeutic implications.

Geospatial Correlation of Amyopathic Dermatomyositis With Fixed Sources of Airborne Pollution: A Retrospective Cohort Study

Objective: Dermatomyositis (DM) may result from exogenous triggers, including airborne pollutants, in genetically susceptible individuals. The United States Environmental Protection Agency's 2011 National Air Toxics Assessment (NATA) models health risks associated with airborne emissions, available by ZIP code tabulation area (ZCTA). Important contributors include point (fixed), on-road, and secondary sources. The objective of this study was to investigate the geospatial distributions of DM and subtypes, classic DM (CDM) and clinically amyopathic DM (CADM), and their associations with airborne pollutants.

Methods: This retrospective cohort study identified 642 adult DM patients from 336 unique ZCTAs. GeoDa v.1.10 was used to calculate global and local Moran's indices and generate local indicator of spatial autocorrelation (LISA) maps. All Moran's indices and LISA maps were permuted 999 times.

Results: Univariate global Moran's indices for DM, CDM, and CADM prevalence were not significant, but LISA maps demonstrated differential local spatial clustering and outliers. CADM prevalence correlated with point sources (bivariate global Moran's index 0.071, pseudo-p = 0.018), in contrast to CDM (−0.0053, pseudo-p = 0.46). Bivariate global Moran's indices for DM, CDM, and CADM prevalence did not correlate with other airborne toxics, but bivariate LISA maps revealed local spatial clustering and outliers.

Conclusion: Prevalence of CADM, but not CDM, is geospatially correlated with fixed sources of airborne emissions. This effect is small but significant and may support the hypothesis that triggering exposures influence disease phenotype. Important limitations are NATA data and ZCTA population estimates were collected from 2011 and ZCTA of residence may not have been where patients had greatest airborne pollutant exposure.

Evaluation of the reliability and validity of the Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI) in paediatric cutaneous lupus among paediatric dermatologists and rheumatologists

BACKGROUND

The Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI) is a reliable outcome measure for cutaneous lupus erythematosus (CLE) in adults used in clinical trials. However, it has not been validated in children, limiting clinical trials for paediatric CLE.

OBJECTIVES

This study aimed to validate the CLASI in paediatrics.

METHODS

Eleven paediatric patients with CLE, six dermatologists and six rheumatologists participated. The physicians were trained to use the CLASI and Physician's Global Assessment (PGA), and individually rated all patients using both tools. Each physician reassessed two randomly selected patients. Within each physician group, the intraclass correlation coefficient (ICC) was calculated to assess the reliability of each measure.

RESULTS

CLASI activity scores demonstrated excellent inter- and intrarater reliability (ICC > 0·90), while the PGA activity scores had good inter-rater reliability (ICC 0·73-0·77) among both specialties. PGA activity scores showed excellent (ICC 0·89) and good intrarater reliability (ICC 0·76) for dermatologists and rheumatologists, respectively. Limitations of this study include the small sample size of patients and potential recall bias during the physician rerating session.

CONCLUSIONS

CLASI activity measurement showed excellent inter- and intrarater reliability in paediatric CLE and superiority over the PGA. These results demonstrate that the CLASI is a reliable and valid outcome instrument for paediatric CLE.

Systemic sclerosis: Current concepts of skin and systemic manifestations

Systemic sclerosis is an uncommon autoimmune connective tissue disease with multiorgan system involvement and significant associated morbidity and mortality. Cutaneous signs and clinical manifestations are of particular importance, as they may be recognized before systemic manifestations, allowing earlier risk stratification into the limited and diffuse cutaneous subtypes, as well as earlier initiation of treatment. Important cutaneous manifestations include Raynaud's phenomenon, digital ulcers, cutaneous sclerosis, calcinosis cutis, telangiectasias, pruritus, and dyspigmentation. Despite investigation of a wide variety of treatments, no FDA-approved pharmacologic therapies exist for systemic sclerosis, and data from high-quality studies are limited. In the following review, we will discuss skin-directed therapies. Although there is evidence to support specific treatments for Raynaud's phenomenon, digital ulcers, and cutaneous sclerosis, there are limited rigorous studies evaluating the treatment of other cutaneous signs and clinical manifestations. Additional randomized-controlled trials and large observational studies are necessary to develop future evidence-based treatment options.

Fulminant Mycosis Fungoides with Tissue Eosinophilia: A Unique Presentation of Two Cases with Acro-Periorbital Ulceration and An Aggressive Clinical Course

We describe two unique cases of fulminant mycosis fungoides with remarkably similar and aggressive clinical courses resulting in death. Both cases demonstrated ulcerated palmar and periorbital plaques and marked tissue eosinophilia, which was confirmed by T-cell receptor γ chain gene rearrangement studies to display identical monoclonality at temporally and anatomically distinct sites. Dense eosinophilic infiltrates on biopsy led to misdiagnosis of inflammatory dermatoses in both instances.

While mycosis fungoides may be challenging to diagnose histologically, the presence of eosinophils in progressive disease may herald a poor prognosis and should not exclude the diagnosis.

The Impact of Competitive Trait Anxiety on Collegiate Powerlifting Performance

Judge, LW, Urbina, LJ, Hoover, DL, Craig, BW, Judge, LM, Leitzelar, BM, Pearson, DR, Holtzclaw, KA, and Bellar, DM. The impact of competitive trait anxiety on collegiate powerlifting performance. J Strength Cond Res 30(9): 2399-2405, 2016-The purpose of this study was to determine the relationship between competitive trait anxiety measures and powerlifting (PL) performance. Thirty-six collegiate powerlifters on club teams from 3 universities were recruited during a competition (men = 26, women = 10; age = 19.9 ± 1.5 years; height = 172.5 ± 8.6 cm; weight = 81.4 ± 21.0 kg). The athletes were distributed across weight classes for collegiate PL (47.6 kg: 1; 51.7 kg: 1; 54.9 kg: 1; 59.8 kg: 3; 67.1 kg: 2; 74.8 kg: 7; 82.1 kg: 4; 89.8 kg: 9; 99.8 kg: 5; super heavyweight: 3). A survey containing questions about PL performance history and the 15-item Sport Competition Anxiety Test (SCAT) were administered to the participants before competing. The SCAT total was negatively correlated (r = -0.397; p = 0.02) to the athletes' percentage of best total achieved in the competition (actual performance total/best comp total × 100). Of the individual lifts, the SCAT score was negatively correlated to the personal best for bench press (r = -0.368; p = 0.03) and deadlift (r = -0.317, p = 0.05), but did not significantly correlate for squat (r = -0.182, p = 0.27). These results indicate a negative correlation between the SCAT score and athletes' personal best totals in PL. Increased SCAT scores were associated with decreased personal best PL totals. The results suggest that competitive trait anxiety may have negatively impacted performance and that some PL athletes may benefit from interventions aimed at decreasing anxiety before and during performance.

Amino acid supplements and recovery from high-intensity resistance training

The purpose of this study was to investigate whether short-term amino acid supplementation could maintain a short-term net anabolic hormonal profile and decrease muscle cell damage during a period of high-intensity resistance training (overreaching), thereby enhancing recovery and decreasing the risk of injury and illness. Eight previously resistance trained males were randomly assigned to either a high branched chain amino acids (BCAA) or placebo group. Subjects consumed the supplement for 3 weeks before commencing a fourth week of supplementation with concomitant high-intensity total-body resistance training (overreaching) (3 x 6-8 repetitions maximum, 8 exercises). Blood was drawn prior to and after supplementation, then again after 2 and 4 days of training. Serum was analyzed for testosterone, cortisol, and creatine kinase. Serum testosterone levels were significantly higher (p < 0.001), and cortisol and creatine kinase levels were significantly lower (p < 0.001, and p = 0.004, respectively) in the BCAA group during and following resistance training. These findings suggest that short-term amino acid supplementation, which is high in BCAA, may produce a net anabolic hormonal profile while attenuating training-induced increases in muscle tissue damage. Athletes' nutrient intake, which periodically increases amino acid intake to reflect the increased need for recovery during periods of overreaching, may increase subsequent competitive performance while decreasing the risk of injury or illness.

Determination of functional strength imbalance of the lower extremities

The purposes of this study were (a) to determine whether a significant strength imbalance existed between the left and right or dominant (D) and nondominant (ND) legs and (b) to investigate possible correlations among various unilateral and bilateral closed kinetic chain tests, including a field test, and traditional isokinetic dynamometry used to determine strength imbalance. Fourteen Division I collegiate women softball players (20.2 +/- 1.4 years) volunteered to undergo measures of average peak torque for isokinetic flexion and extension at 60 degrees .s(-1) and 240 degrees .s(-1); in addition, measures of peak and average force of each leg during parallel back squat, 2-legged vertical jump, and single-leg vertical jump and performance in a 5-hop test were examined. Significant differences of between 4.2% and 16.0% were evident for all measures except for average force during single-leg vertical jump between the D and ND limbs, thus revealing a significant strength imbalance. The 5-hop test revealed a significant difference between D and ND limbs and showed a moderate correlation with more sophisticated laboratory tests, suggesting a potential use as a field test for the identification of strength imbalance. The results of this study indicate that a significant strength imbalance can exist even in collegiate level athletes, and future research should be conducted to determine how detrimental these imbalances could be in terms of peak performance for athletes, as well as the implications for injury risk.

Elevated plasma 4-pyridoxic acid in renal insufficiency

BACKGROUND

Renal insufficiency is associated with altered vitamin B-6 metabolism. We have observed high concentrations of 4-pyridoxic acid, the major catabolite of vitamin B-6 metabolism, in plasma during renal insufficiency.

OBJECTIVE

The objective was to evaluate the renal handling of 4-pyridoxic acid and the effects of renal dysfunction on vitamin B-6 metabolism.

DESIGN

We measured the renal clearance of 4-pyridoxic acid and creatinine in 17 nonpregnant, 17 pregnant, and 16 lactating women. We then examined the influence of vitamin B-6 or alkaline phosphatase activity on the ratio of 4-pyridoxic acid to pyridoxal (PA:PL) in plasma in 10 men receiving a low (0.4 mg pyridoxine.HCl/d) or high (200 mg pyridoxine.HCl/d) vitamin B-6 intake for 6 wk, in 10 healthy subjects during a 21-d fast, in 1235 plasma samples from 799 people screened for hypophosphatasia, and in 67 subjects with a range of serum creatinine concentrations.

RESULTS

Renal clearance of 4-pyridoxic acid was 232 +/- 94 mL/min in nonpregnant women, 337 +/- 140 mL/min in pregnant women, and 215 +/- 103 mL/min in lactating healthy women. These values were approximately twice the creatinine clearance, indicating that 4-pyridoxic acid is at least partially eliminated by tubular secretion. Elevated plasma creatinine concentrations were associated with marked elevations in 4-pyridoxic acid and PA:PL. PA:PL was not affected by wide variations in vitamin B-6 intake or by the wide range of pyridoxal-P concentrations encountered while screening for hypophosphatasia.

CONCLUSIONS

Plasma 4-pyridoxic acid concentrations are markedly elevated in renal insufficiency. Plasma PA:PL can distinguish between increases in 4-pyridoxic acid concentrations due to increased dietary intake and those due to renal insufficiency.

Performance and muscle fiber adaptations to creatine supplementation and heavy resistance training

PURPOSE

The purpose of this study was to examine the effect of creatine supplementation in conjunction with resistance training on physiological adaptations including muscle fiber hypertrophy and muscle creatine accumulation.

METHODS

Nineteen healthy resistance-trained men were matched and then randomly assigned in a double-blind fashion to either a creatine (N = 10) or placebo (N = 9) group. Periodized heavy resistance training was performed for 12 wk. Creatine or placebo capsules were consumed (25 g x d(-1)) for 1 wk followed by a maintenance dose (5 g x d(-1)) for the remainder of the training.

RESULTS

After 12 wk, significant (P < or = 0.05) increases in body mass and fat-free mass were greater in creatine (6.3% and 6.3%, respectively) than placebo (3.6% and 3.1%, respectively) subjects. After 12 wk, increases in bench press and squat were greater in creatine (24% and 32%, respectively) than placebo (16% and 24%, respectively) subjects. Compared with placebo subjects, creatine subjects demonstrated significantly greater increases in Type I (35% vs 11%), IIA (36% vs 15%), and IIAB (35% vs 6%) muscle fiber cross-sectional areas. Muscle total creatine concentrations were unchanged in placebo subjects. Muscle creatine was significantly elevated after 1 wk in creatine subjects (22%), and values remained significantly greater than placebo subjects after 12 wk. Average volume lifted in the bench press during training was significantly greater in creatine subjects during weeks 5-8. No negative side effects to the supplementation were reported.

CONCLUSION

Creatine supplementation enhanced fat-free mass, physical performance, and muscle morphology in response to heavy resistance training, presumably mediated via higher quality training sessions.

Calf muscle strength in former elite distance runners

The purpose of this investigation was to examine calf muscle strength and cross-sectional area in 29 middle-aged men (current mean = 48.3 +/- 3.1 years) who had significant differences in their physical activity levels. These men were initially evaluated to determine the physiological requirements for successful distance running in the late 1960s at a time when they were all considered elite distance runners. Based on their training regimens in the interim between testing, subjects were described as highly trained (HI; n = 10), fitness trained (FIT; n = 12), or untrained (UT; n = 7). In addition, an aged-matched sedentary group (CON; n = 7) was tested. Each subject was evaluated for VO2max, plantar flexion calf muscle strength and cross-sectional area (CSA) of the lower leg (gastrocnemius and soleus). Muscle CSA was determined by computed tomography, whereas calf strength measurements were made using a specially designed leg restraint system and an isokinetic dynamometer. There were no significant differences in plantar flexion strength (at 60 and 180 degrees/s) or CSA of the gastrocnemius and soleus muscles among the groups. Calf muscle strength per CSA was also similar at both test velocities for all groups. These data demonstrate that middle-aged distance runners who have continued to run at a relatively high level for 20-25 years have similar calf muscle CSA and strength compared with aged-matched males who run significantly less or not at all.

Pyridoxic acid excretion during low vitamin B-6 intake, total fasting, and bed rest

Vitamin B-6 metabolism in 10 volunteers during 21 d of total fasting was compared with results from 10 men consuming a diet low only in vitamin B-6 (1.76 mumol/d) and with men consuming a normal diet during bed rest. At the end of the fast mean plasma concentrations of vitamin B-6 metabolites and urinary excretion of 4-pyridoxic acid tended to be higher in the fasting subjects than in the low-vitamin B-6 group. The fasting subjects lost approximately 10% of their total vitamin B-6 pool and approximately 13% of their body weight. The low-vitamin B-6 group lost only approximately 4% of their vitamin B-6 pool. Compared with baseline, urinary excretion of pyridoxic acid was significantly increased during 17 wk of bed rest. There was no increase in pyridoxic acid excretion during a second 15-d bed rest study. These data suggest the possibility of complex interactions between diet and muscle metabolism that may influence indexes that are frequently used to assess vitamin B-6 status.