Optical calibration of the SuperCam instrument body unit spectrometers

The SuperCam remote sensing instrument on NASA's Perseverance rover is capable of four spectroscopic techniques, remote micro-imaging, and audio recording. These analytical techniques provide details of the chemistry and mineralogy of the rocks and soils probed in the Jezero Crater on Mars. Here we present the methods used for optical calibration of the three spectrometers covering the 243-853 nm range used by three of the four spectroscopic techniques. We derive the instrument optical response, which characterizes the instrument sensitivity to incident radiation as a function of a wavelength. The instrument optical response function derived here is an essential step in the interpretation of the spectra returned by SuperCam as it converts the observed spectra, reported by the instrument as "digital counts" from an analog to digital converter, into physical values of spectral radiance.

Statistical shape modeling of the hip and the association with hip osteoarthritis: a systematic review

OBJECTIVE

To summarize available evidence on the association between hip shape as quantified by statistical shape modeling (SSM) and the incidence or progression of hip osteoarthritis.

DESIGN

We conducted a systematic search of five electronic databases, based on a registered protocol (available: PROSPERO CRD42020145411). Articles presenting original data on the longitudinal relationship between radiographic hip shape (quantified by SSM) and hip OA were eligible. Quantitative meta-analysis was precluded because of the use of different SSM models across studies. We used the Newcastle-Ottawa Scale (NOS) for risk of bias assessment.

RESULTS

Nine studies (6,483 hips analyzed with SSM) were included in this review. The SSM models used to describe hip shape ranged from 16 points on the femoral head to 85 points on the proximal femur and hemipelvis. Multiple hip shape features and combinations thereof were associated with incident or progressive hip OA. Shape variants that seemed to be consistently associated with hip OA across studies were acetabular dysplasia, cam morphology, and deviations in acetabular version (either excessive anteversion or retroversion).

CONCLUSIONS

Various radiographic, SSM-defined hip shape features are associated with hip OA. Some hip shape features only seem to increase the risk for hip OA when combined together. The heterogeneity of the used SSM models across studies precludes the estimation of pooled effect sizes. Further studies using the same SSM model and definition of hip OA are needed to allow for the comparison of outcomes across studies, and to validate the found associations.

The SuperCam Instrument Suite on the NASA Mars 2020 Rover: Body Unit and Combined System Tests

The SuperCam instrument suite provides the Mars 2020 rover, Perseverance, with a number of versatile remote-sensing techniques that can be used at long distance as well as within the robotic-arm workspace. These include laser-induced breakdown spectroscopy (LIBS), remote time-resolved Raman and luminescence spectroscopies, and visible and infrared (VISIR; separately referred to as VIS and IR) reflectance spectroscopy. A remote micro-imager (RMI) provides high-resolution color context imaging, and a microphone can be used as a stand-alone tool for environmental studies or to determine physical properties of rocks and soils from shock waves of laser-produced plasmas. SuperCam is built in three parts: The mast unit (MU), consisting of the laser, telescope, RMI, IR spectrometer, and associated electronics, is described in a companion paper. The on-board calibration targets are described in another companion paper. Here we describe SuperCam's body unit (BU) and testing of the integrated instrument. The BU, mounted inside the rover body, receives light from the MU via a 5.8 m optical fiber. The light is split into three wavelength bands by a demultiplexer, and is routed via fiber bundles to three optical spectrometers, two of which (UV and violet; 245-340 and 385-465 nm) are crossed Czerny-Turner reflection spectrometers, nearly identical to their counterparts on ChemCam. The third is a high-efficiency transmission spectrometer containing an optical intensifier capable of gating exposures to 100 ns or longer, with variable delay times relative to the laser pulse. This spectrometer covers 535-853 nm ( 105 - 7070 cm - 1 Raman shift relative to the 532 nm green laser beam) with 12 cm - 1 full-width at half-maximum peak resolution in the Raman fingerprint region. The BU electronics boards interface with the rover and control the instrument, returning data to the rover. Thermal systems maintain a warm temperature during cruise to Mars to avoid contamination on the optics, and cool the detectors during operations on Mars. Results obtained with the integrated instrument demonstrate its capabilities for LIBS, for which a library of 332 standards was developed. Examples of Raman and VISIR spectroscopy are shown, demonstrating clear mineral identification with both techniques. Luminescence spectra demonstrate the utility of having both spectral and temporal dimensions. Finally, RMI and microphone tests on the rover demonstrate the capabilities of these subsystems as well.

Incidence and progression of hand osteoarthritis in a large community-based cohort: the Johnston County Osteoarthritis Project

OBJECTIVE

To describe the incidence and progression of radiographic and symptomatic hand osteoarthritis (rHOA and sxHOA) in a large community-based cohort.

DESIGN

Data were from the Johnston County OA Project (1999-2015, 12 ± 1.2 years follow-up, age 45+). Participants had bilateral hand radiographs each visit, read for Kellgren-Lawrence grade (KLG) at 30 joints. We defined rHOA as KLG ≥2 in ≥1 joint. SxHOA was defined in a hand/joint with rHOA and self-reported symptoms or tenderness on exam. Incidence was assessed in those without, while progression was assessed in those with, baseline rHOA. Proportions or medians are reported; differences by sex and race were assessed using models appropriate for dichotomous or continuous definitions, additionally adjusted for age, education, body mass index (BMI), and weight change.

RESULTS

Of 800 participants (68% women, 32% African American, mean age 60 years), 327 had baseline rHOA and were older, more often white and female, than those without rHOA (n = 473). The incidence of HOA was high, for rHOA (60%) and for sxHOA (13%). Women were more likely than men to have incident HOA, particularly for distal interphalangeal joint radiographic osteoarthritis (DIP rOA) (adjusted odds ratios (aOR) 1.60 95% confidence intervals (95% CI) [1.03, 2.49]) and sxHOA (aOR 2.98 [1.50, 5.91]). Progressive HOA was more similar by sex, although thumb base rOA progressed more frequently in women than in men (aOR 2.56 [1.44, 4.55]). Particularly HOA incidence, but also progression, was more frequent among whites compared with African Americans.

CONCLUSION

This study provides much needed information about the natural history of HOA, a common and frequently debilitating condition, in the general population.

A machine learning approach to knee osteoarthritis phenotyping: data from the FNIH Biomarkers Consortium

OBJECTIVE

Knee osteoarthritis (KOA) is a heterogeneous condition representing a variety of potentially distinct phenotypes. The purpose of this study was to apply innovative machine learning approaches to KOA phenotyping in order to define progression phenotypes that are potentially more responsive to interventions.

DESIGN

We used publicly available data from the Foundation for the National Institutes of Health (FNIH) osteoarthritis (OA) Biomarkers Consortium, where radiographic (medial joint space narrowing of ≥0.7 mm), and pain progression (increase of ≥9 Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] points) were defined at 48 months, as four mutually exclusive outcome groups (none, both, pain only, radiographic only), along with an extensive set of covariates. We applied distance weighted discrimination (DWD), direction-projection-permutation (DiProPerm) testing, and clustering methods to focus on the contrast (z-scores) between those progressing by both criteria ("progressors") and those progressing by neither ("non-progressors").

RESULTS

Using all observations (597 individuals, 59% women, mean age 62 years and BMI 31 kg/m2) and all 73 baseline variables available in the dataset, there was a clear separation among progressors and non-progressors (z = 10.1). Higher z-scores were seen for the magnetic resonance imaging (MRI)-based variables than for demographic/clinical variables or biochemical markers. Baseline variables with the greatest contribution to non-progression at 48 months included WOMAC pain, lateral meniscal extrusion, and serum N-terminal pro-peptide of collagen IIA (PIIANP), while those contributing to progression included bone marrow lesions, osteophytes, medial meniscal extrusion, and urine C-terminal crosslinked telopeptide type II collagen (CTX-II).

CONCLUSIONS

Using methods that provide a way to assess numerous variables of different types and scalings simultaneously in relation to an outcome of interest enabled a data-driven approach that identified key variables associated with a progression phenotype.

Clinical algorithms to aid osteoarthritis guideline dissemination

BACKGROUND

Numerous scientific organisations have developed evidence-based recommendations aiming to optimise the management of osteoarthritis (OA). Uptake, however, has been suboptimal. The purpose of this exercise was to harmonize the recent recommendations and develop a user-friendly treatment algorithm to facilitate translation of evidence into practice.

METHODS

We updated a previous systematic review on clinical practice guidelines (CPGs) for OA management. The guidelines were assessed using the Appraisal of Guidelines for Research and Evaluation for quality and the standards for developing trustworthy CPGs as established by the National Academy of Medicine (NAM). Four case scenarios and algorithms were developed by consensus of a multidisciplinary panel.

RESULTS

Sixteen guidelines were included in the systematic review. Most recommendations were directed toward physicians and allied health professionals, and most had multi-disciplinary input. Analysis for trustworthiness suggests that many guidelines still present a lack of transparency. A treatment algorithm was developed for each case scenario advised by recommendations from guidelines and based on panel consensus.

CONCLUSION

Strategies to facilitate the implementation of guidelines in clinical practice are necessary. The algorithms proposed are examples of how to apply recommendations in the clinical context, helping the clinician to visualise the patient flow and timing of different treatment modalities.

Novel statistical methodology reveals that hip shape is associated with incident radiographic hip osteoarthritis among African American women

INTRODUCTION

Hip shape is a risk factor for the development of hip osteoarthritis (OA), and current methods to assess hip shape from radiographs are limited; therefore this study explored current and novel methods to assess hip shape.

METHODS

Data from a prior case-control study nested in the Johnston County OA Project were used, including 382 hips (from 342 individuals). Hips were classified by radiographic hip OA (RHOA) status as RHOA cases (baseline Kellgren Lawrence grade [KLG] 0 or 1, follow-up [mean 6 years] KLG ≥ 2) or controls (KLG = 0 or 1 at both baseline and follow-up). Proximal femur shape was assessed using a 60-point model as previously described. The current analysis explored commonly used principal component analysis (PCA), as well as novel statistical methodologies suited to high dimension low sample size settings (Distance Weighted Discrimination [DWD] and Distance Projection Permutation [DiProPerm] hypothesis testing) to assess differences between cases and controls.

RESULTS

Using these novel methodologies, we were able to better characterize morphologic differences by sex and race. In particular, the proximal femurs of African American women demonstrated significantly different shapes between cases and controls, implying an important role for sex and race in the development of RHOA. Notably, discrimination was improved with the use of DWD and DiProPerm compared to PCA.

CONCLUSIONS

DWD with DiProPerm significance testing provides improved discrimination of variation in hip morphology between groups, and enables subgroup analyses even under small sample sizes.

OARSI Clinical Trials Recommendations: Design and conduct of clinical trials for hand osteoarthritis

Hand osteoarthritis (OA) is a very frequent disease, but yet understudied. However, a lot of works have been published in the past 10 years, and much has been done to better understand its clinical course and structural progression. Despite this new knowledge, few therapeutic trials have been conducted in hand OA. The last OARSI recommendations for the conduct of clinical trials in hand OA dates back to 2006. The present recommendations aimed at updating previous recommendations, by incorporating new data. The purpose of this expert opinion, consensus driven exercise is to provide evidence-based guidance on the design, execution and analysis of clinical trials in hand OA, where published evidence is available, supplemented by expert opinion, where evidence is lacking, to perform clinical trials in hand OA, both for symptom and for structure-modification. They indicate core outcome measurement sets for studies in hand OA, and list the methods and instruments that should be used to measure symptoms or structure. For both symptom- and structure-modification, at least pain, physical function, patient global assessment, HR-QoL, joint activity and hand strength should be assessed. In addition, for structure-modification trials, structural progression should be measured by radiographic changes. We also provide a research agenda listing many unsolved issues that seem to most urgently need to be addressed from the perspective of performing "good" clinical trials in hand OA. These updated OARSI recommendations should allow for better standardizing the conduct of clinical trials in hand OA in the next future.

OARSI Clinical Trials Recommendations: Design and conduct of clinical trials for hip osteoarthritis

The ability to assess the efficacy and effectiveness of an intervention for the treatment of hip osteoarthritis (OA) requires strong clinical trial methodology. This consensus paper provides recommendations based on a narrative literature review and best judgment of the members of the committee for clinical trials of hip OA. We provide recommendations on clinical trial design, outcome measures, including structural (radiography), and patient and physician global assessments, performance based measures, molecular markers and experimental endpoints including MRI imaging. This information can be utilized by sponsors of trials for new therapeutic agents for hip OA.

Influence of demographic factors and sport type on growth hormone-responsive markers in elite athletes

CONTEXT

GH-responsive markers of the IGF system and of collagen turnover hold promise as the basis of a GH doping test.

OBJECTIVE

The purpose of this study was to determine the influence of age, gender, body mass index (BMI), ethnicity, and sporting type on GH-responsive serum markers in a large cohort of elite athletes from different ethnic backgrounds.

DESIGN

The study was designed as a cross-sectional study.

PARTICIPANTS

A total of 1103 elite athletes (699 males, 404 females), aged 22.2 +/- 5.2 yr, from 12 countries and 10 major sporting categories participated in this study.

MAIN OUTCOME MEASURES

Serum IGF-I, IGF binding protein-3 (IGFBP-3), acid labile subunit (ALS), and collagen markers [N-terminal propeptide of type I procollagen (PINP), C-terminal telopeptide of type I collagen (ICTP), N-terminal propeptide of type III procollagen (PIIINP)] were measured.

RESULTS

There was a significant negative correlation (r = -0.14 to -0.58, P < 0.0005) between age and each of the GH-responsive markers. Serum IGF-I, IGFBP-3, and ALS were all lower (P < 0.05), whereas the collagen markers PINP, ICTP, and PIIINP were higher (P < 0.05) in men than in women. Multiple regression analysis indicated that age, gender, BMI, and ethnicity accounted for 23-54% of total between-subject variability of the markers. Age and gender cumulatively accounted for 91% of the attributable variation of IGF-I and more than 80% for PINP, ICTP, and PIIINP. Gender exerted the greatest effect on ALS (48%), and BMI accounted for less than 12% attributable variation for all markers. The influence of ethnicity was greatest for IGFBP-3 and ALS; however, for the other markers, it accounted for less than 6% attributable variation. Analysis of 995 athletes indicated that sporting type contributed 5-19% of attributable variation.

CONCLUSIONS

Age and gender were major determinants of variability of GH-responsive markers except for IGFBP-3 and ALS. Ethnicity is unlikely to confound the validity of a GH doping test based on IGF-I and these collagen markers.

Erythropoietin administration does not influence the GH--IGF axis or makers of bone turnover in recreational athletes

OBJECTIVE

Measurement of biochemical markers of the IGF-system and of collagen turnover is a potential approach to detect GH abuse in sport. These markers are increased in patients on dialysis treated with recombinant human erythropoietin (r-HuEPO), mimicking the effects of GH. The aim was to determine whether r-HuEPO induces similar effects on the IGF-system and collagen turnover in healthy athletes.

SUBJECTS AND MEASUREMENTS

Young male Caucasian recreational athletes were administered 50 U/kg r-HuEPO (n=14) or placebo (n=16) three times a week for 25 days, followed by a 4-week wash-out period. IGF-I, IGFBP-3, the acid labile subunit (ALS), N-terminal propeptide of type I collagen (PINP), C-terminal telopeptide of type I collagen (ICTP) and N-terminal propeptide of type III collagen (PIIINP) were measured in samples collected at baseline (two samples), after 10, 22 and 24 days of r-HuEPO treatment and at the end of the 4-week wash-out period.

RESULTS

Treatment with r-HuEPO resulted in approximately threefold elevation of serum EPO and marked elevation of markers of erythropoiesis. There was no significant treatment effect of r-HuEPO compared to baseline on IGF-I, IGFBP-3, ALS, PINP, ICTP or PIIINP.

CONCLUSIONS

r-HuEPO administration did not change markers of the IGF-system and of collagen turnover in young healthy male athletes. Therefore, use of r-HuEPO in athletes should not affect the validity of a GH doping test using these GH-responsive markers.

Osteocyte viability with glucocorticoid treatment: relation to histomorphometry

BACKGROUND

Glucocorticoid induced osteoporosis is a common clinical problem.

OBJECTIVE

To determine the pathophysiology of glucocorticoid induced osteoarthritis at the organ level.

METHODS

Iliac crest biopsy specimens were obtained from nine patients receiving prednisone treatment for rheumatoid arthritis. Osteocyte viability and histomorphometric indices were assessed.

RESULTS

Compared with controls, glucocorticoid treated subjects had reduced trabecular thickness and increased erosion. The number of viable osteocytes was significantly decreased in glucocorticoid treated patients compared with controls.

CONCLUSION

The impaired bone formation, increased erosion and, importantly, loss of viable osteocytes are all likely to contribute to the increased risk of fracture in these patients.

HRPT2 mutations are associated with malignancy in sporadic parathyroid tumours

BACKGROUND

Hyperparathyroidism is a common endocrinopathy characterised by the formation of parathyroid tumours. In this study, we determine the role of the recently identified gene, HRPT2, in parathyroid tumorigenesis.

METHODS

Mutation analysis of HRPT2 was undertaken in 60 parathyroid tumours: five HPT-JT, three FIHP, three MEN 1, one MEN 2A, 25 sporadic adenomas, 17 hyperplastic glands, two lithium associated tumours, and four sporadic carcinomas. Loss of heterozygosity at 1q24-32 was performed on a subset of these tumours.

RESULTS

HRPT2 somatic mutations were detected in four of four sporadic parathyroid carcinoma samples, and germline mutations were found in five of five HPT-JT parathyroid tumours (two families) and two parathyroid tumours from one FIHP family. One HPT-JT tumour with germline mutation also harboured a somatic mutation. In total, seven novel and one previously reported mutation were identified. "Two-hits" (double mutations or one mutation and loss of heterozygosity at 1q24-32) affecting HRPT2 were found in two sporadic carcinomas, two HPT-JT-related and two FIHP related tumours.

CONCLUSIONS

The results in this study support the role of HRPT2 as a tumour suppressor gene in sporadic parathyroid carcinoma, and provide further evidence for HRPT2 as the causative gene in HPT-JT, and a subset of FIHP. In light of the strong association between mutations of HRPT2 and sporadic parathyroid carcinoma demonstrated in this study, it is hypothesised that HRPT2 mutation is an early event that may lead to parathyroid malignancy and suggest intragenic mutation of HRPT2 as a marker of malignant potential in both familial and sporadic parathyroid tumours.

Genetic analysis of lithium-associated parathyroid tumors

OBJECTIVE

The aim of this study was to determine the primary genetic events that may underlie the formation of parathyroid tumors in patients with lithium-associated hyperparathyroidism (HPT).

METHODS

Comparative genomic hybridization (CGH), loss of heterozygosity (LOH) and multiple endocrine neoplasia type 1 gene (MEN1) mutation analysis were used to analyze twelve parathyroid tumors from nine patients with lithium-associated HPT. For comparison, CGH was also carried out in a non-lithium-associated group of thirteen sporadic parathyroid tumors.

RESULTS

A higher prevalence of multiglandular disease in the lithium-associated HPT patients compared with the idiopathic sporadic patients was observed (Fisher's exact test, P=0.02). CGH alterations were detected in four lithium-associated parathyroid tumors, involving loss at 1p, 11, 15q, 22q and gain of the X chromosome. In addition, one of these four cases exhibited LOH at 11q13 and was found to contain a novel somatic MEN1 mutation (c.1193insTAC). Although fewer lithium-associated parathyroid tumors were shown to contain genetic alterations compared with the sporadic parathyroid tumors, the changes detected were those frequently associated with both familial and sporadic parathyroid tumorigenesis.

CONCLUSION

This is, to our knowledge, the first genetic analysis of parathyroid tumors in lithium-associated HPT patients. Our data indicated that the majority of lithium-associated parathyroid tumors do not contain gross chromosomal alterations and suggest that in most cases the tumorigenic pathway is independent of MEN1 and genes at 1p34.3-pter and 1q21-q32. It is possible that other discrete genetic alterations or epigenetic changes, not screened for in this study, could also be responsible for parathyroid tumorigenesis in lithium-associated HPT.

Diagnosis of a patient with oncogenic osteomalacia using a phosphate uptake bioassay of serum and magnetic resonance imaging

A previously healthy man with no family history of fractures presented with muscle pain, back pain and height loss. Investigations revealed hypophosphataemia, phosphaturia, undetectable serum 1,25-dihydroxyvitamin D and severe osteomalacia on bone biopsy, suggestive of a diagnosis of oncogenic osteomalacia. Thorough physical examination did not locate a tumour. Support for the diagnosis was obtained by detection of phosphate uptake inhibitory activity in a blinded sample of the patient's serum using a renal cell bioassay. On the basis of detection of this bioactivity, a total body magnetic resonance (MR) examination was performed. A small tumour was located in the right leg. Removal of the tumour resulted in the rapid reversal of symptoms and the abnormal biochemistry typical of oncogenic osteomalacia. Inhibitory activity was also demonstrated using the bioassay in serum from two other patients with confirmed or presumptive oncogenic osteomalacia, but not in serum from two patients with hypophosphataemia of other origin. This is the first case to be reported in which the diagnosis of oncogenic osteomalacia was assisted by demonstration of inhibitory activity of the patient's serum in a renal cell phosphate bioassay that provided an impetus for total body MR imaging.

Mutational analysis and genotype-phenotype correlation of the PHEX gene in X-linked hypophosphatemic rickets

PHEX is the gene defective in X-linked hypophosphatemic rickets. In this study, analysis of PHEX revealed mutations in 22 hypophosphatemic rickets patients, including 16 of 28 patients in whom all 22 PHEX exons were studied. In 13 patients, in whom no PHEX mutation had been previously detected in 17 exons, the remaining 5 PHEX exons were analyzed and mutations found in 6 patients. Twenty different mutations were identified, including 16 mutations predicted to truncate PHEX and 4 missense mutations. Phenotype analysis was performed on 31 hypophosphatemic rickets patients with PHEX mutations, including the 22 patients identified in this study, 9 patients previously identified, and affected family members. No correlation was found between the severity of disease and the type or location of the mutation. However, among patients with a family history of hypophosphatemic rickets, there was a trend toward more severe skeletal disease in patients with truncating mutations. Family members in more recent generations had a milder phenotype. Postpubertal males had a more severe dental phenotype. In conclusion, although identifying mutations in PHEX may have limited prognostic value, genetic testing may be useful for the early identification and treatment of affected individuals. Furthermore, this study suggests that other genes and environmental factors affect the severity of hypophosphatemic rickets.

Phosphate wasting in oncogenic osteomalacia: PHEX is normal and the tumor-derived factor has unique properties

Oncogenic osteomalacia (OOM) is characterized by renal phosphate wasting and abnormal metabolism of vitamin D, somewhat similar to the phenotype of X-linked hypophosphatemic rickets (HYP). DNA from OOM tumor cells was analyzed for mutations in the PHEX gene, which is mutated in HYP. Screening for mutations by single-strand conformation polymorphism analysis and subsequent sequencing of all the exons revealed no mutations. Conditioned media from long-term cultures of OOM tumor cells were used to further characterize the physical properties of the phosphate-regulating factor and its mechanism of action. Inhibition of OK 3B2 cell renal phosphate transport by conditioned media was dose-dependent and maximal after 20 h. This time course differed from that of parathyroid hormone (PTH). The bioactivity was stable to mild acid and alkali treatment and freeze drying and was retained in the aqueous phase following organic solvent extraction. The activity was not suppressed by heat or by treatment with trypsin but was suppressed by the protease papain and had an apparent molecular weight of < 5000. No change was detected in the expression of type II sodium/phosphate cotransporter (NaPi) mRNA in OK 3B2 cells in response to conditioned media, unlike the reduction seen in Hyp mice. In the presence of colchicine or cytochalasin D, the inhibitory response to conditioned media was reduced, similar to the effect of these agents on the response to PTH. Cycloheximide also suppressed the inhibitory response of conditioned media, but not the response to PTH. These studies indicate that mutations in the PHEX gene are unlikely to be responsible for OOM and suggest that the tumor-derived factor that inhibits phosphate uptake is a small protein that does not downregulate type II NaPi mRNA, and requires an intact cytoskeleton and protein synthesis for activity.

Muscle abnormalities in juvenile dermatomyositis patients: P-31 magnetic resonance spectroscopy studies

OBJECTIVE

To characterize metabolic abnormalities in the muscles of children with the juvenile variant of dermatomyositis (JDM) by the use of noninvasive P-31 magnetic resonance spectroscopy (MRS).

METHODS

Thirteen patients with JDM (ages 4-16 years) were studied. Biochemical status was evaluated with P-31 MRS by determining the concentrations of the high-energy phosphate compounds, ATP and phosphocreatine (PCr), ratios of inorganic phosphate (Pi) to PCr (Pi:PCr ratio), levels of free cytosolic ADP, and phosphorylation potentials (PPs) during rest, exercise, and recovery.

RESULTS

Significant metabolic abnormalities were observed in the thigh muscles of 10 severely affected patients during rest, 2 graded levels of exercise, and recovery. Mean ATP and PCr levels in the muscles of JDM patients were 35-40% below the normal control values (P < 0.003). These data, along with elevated Pi:PCr ratios, higher ADP levels, and abnormal values for PPs, indicated defective oxidative phosphorylation in the mitochondria of diseased JDM muscles. MRS findings were normal in 2 additional patients who had improved with prednisone treatment and in 1 patient who had no muscle weakness (amyopathic variant of JDM).

CONCLUSION

JDM patients can be monitored with noninvasive P-31 MRS without sedation. Biochemical defects in energy metabolism are concordant with the weakness and fatigue reported by JDM patients. Quantitative MRS data are useful for evaluating patients and optimizing drug treatment regimens.

Tumor expression studies indicate that HEM-1 is unlikely to be the active factor in oncogenic osteomalacia

HEM-1 was isolated as a putative factor responsible for oncogenic osteomalacia by Kumar et al. (Proc Assoc Am Phys 107:296-305; 1995). The cDNA was identified on the basis of PTH-like immunoreactivity; however, no studies have been reported of the expression of HEM-1 mRNA in oncogenic osteomalacia tumors. In this study, expression of HEM-1 mRNA was investigated in two oncogenic osteomalacia tumors and in a series of normal tissues. An HEM-1 PCR product was amplified from a cDNA library from one of the tumors, with six base changes identified, as compared with the published sequence. No expression was detected, however, in the oncogenic osteomalacia tumors either by Northern blot analysis or by reverse transcriptase PCR. This indicates that, although a region of HEM-1 sequence is present in the tumor cell cDNA library, any HEM-1 expression must be at very low levels. It is unlikely, therefore, that the HEM-1 product is the active factor responsible for oncogenic osteomalacia. In the normal tissues examined, human placenta, fibroblasts, parathyroid gland, liver, fetal bone, and rat kidney cortex, HEM-1 mRNA was not detected, suggesting that it does not have a physiological role in these tissues.

Oncogenic osteomalacia: is there a new phosphate regulating hormone?

Oncogenic osteomalacia is a syndrome associated with rare, usually mesenchymal tumours, which is characterized by hypophosphataemia, phosphaturia and low concentrations of 1,25-dihydroxyvitamin D. The reversal of clinical and biochemical abnormalities following removal of the tumour, indicates it is the source of a humoral factor that is responsible for these abnormalities. It has been demonstrated that the humoral factor inhibits renal phosphate uptake and reduces 1,25-dihydroxyvitamin D production. Although there is evidence that it may act via parathyroid hormone/parathyroid hormone-related peptide receptors and may be a peptide, the factor has not yet been identified, nor has its relationship to factors involved in X-linked hypophosphataemic rickets been established. We propose unifying hypotheses for the pathogenesis of oncogenic osteomalacia and X-linked hypophosphataemic rickets which involve defects in the PEX gene. These hypotheses do not fully explain all the available data and it remains possible that hormone(s) with little or no role in X-linked hypophosphataemic rickets may be responsible for oncogenic osteomalacia.

Coping and support effects on mothers' stress responses to their child's hematopoietic stem cell transplantation

A hematopoietic stem cell transplantation (HSCT) is used as a treatment for cancer or nonmalignant hematological disorders in children. Little information is known about how an HSCT affects the mothers of these patients. The purposes of this repeated measures study were to examine the stress responses of mothers at four times during their child's hospitalization for an HSCT and to determine the relationships among mothers' stress responses and the resources for coping and social support. Maternal anxiety mean scores decreased significantly over time although a majority of the mothers had moderately high anxiety scores at all times. Mean scores of mothers' depressive symptomatologies decreased significantly over time. A majority of the mothers had depressive symptomatology scores above the cut-off score that indicates being at-risk for developing depression. At each of four data collection times, a specific coping style (defined as active reviewing of feelings or information associated with the situation) significantly explained the variance in mothers' scores for anxiety, depressive symptomatology, somatic complaints, and sleep behavior. Social support significantly explained differences in depressive symptomatology scores only at data collection times 1 and 3. Health care providers need to assess mothers for stress responses and assist them in dealing with their feelings and in understanding the information associated with an HSCT.

Characteristics of tumor cell bioactivity in oncogenic osteomalacia

Oncogenic osteomalacia is a condition where renal phosphate wasting occurs causing defective mineralisation, in the presence of a tumor. Cultures of cells were established from a hemangiopericytoma resected from a patient with oncogenic osteomalacia. Conditioned media from the cells inhibited phosphate uptake in opossum kidney cells and stimulated of cAMP in rat osteosarcoma cells, a standard parathyroid hormone (PTH)-like assay. This cAMP stimulation was suppressed by the PTH analogue, 3-34 bPTH and also by heat and trypsin treatment of the media. Tests of conditioned media for PTH and parathyroid hormone related protein (PTHrP) immunoreactivity were negative, however, and no hybridisation to probes for PTH, PTHrP or human stanniocalcin was detected in tumor cell RNA on Northern blot. These data support the hypothesis that tumors responsible for oncogenic osteomalacia produce a humoral substance that reduces renal phosphate reabsorption and provide evidence that the factor may act via PTH/PTHrP receptors.

Impotence in medical clinic outpatients

One thousand one hundred eighty men in a medical outpatient clinic were screened as to the presence of impotence. Four hundred one men (34%) were impotent, and of those, 188 (47%) chose to be examined for their problem. After a comprehensive evaluation the following diagnoses were obtained: medication effect, 25%; psychogenic, 14%; neurological, 7%; urologic, 6%; primary hypogonadism, 10%; secondary hypogonadism, 9%; diabetes mellitus, 9%; hypothyroidism, 5%; hyperthyroidism, 1%; hyperprolactinemia, 4%; miscellaneous, 4%; and unknown causes, 7%. The mean age of the impotent patients was 59.4 years, and the prevalence of alcoholism was 7%. Luteinizing hormone, follicle-stimulating hormone, testosterone, thyroxine, triiodothyronine (T3), T3 resin uptake, and prolactin studies were necessary to diagnose individual cases. We conclude that erectile dysfunction is a common and often overlooked problem in middle-aged men followed in a medical clinic.

Specificity of finger pulse volume feedback during relaxation

The effect of biofeedback during brief periods of relaxation was examined. Two groups (10 subjects in each group) were asked to relax as completely as possible during a series of six 3-minute relaxation periods in each of two 1-hr sessions. One group received biofeedback based on finger pulse volume (FPV) during the relaxation trials, while the other group received no biofeedback. Measures of heart rate, respiration rate, skin conductance level, and FPV were recorded during the sessions, and subjective ratings concerning relaxation were obtained after each session. The results showed that FPV scores for the groups differed during the relaxation trials of the second session, but other measures failed to distinguish between the groups. The group that received FPV feedback revealed a significantly higher level of FPV (relative to baseline) than the group that received no feedback.

The role of blood osmolality and volume in regulating vasopressin secretion in the rat

A sensitive and specific radioimmunoassay for plasma arginine vasopressin (AVP) has been used to study the effects of blood osmolality and volume in regulating AVP secretion in unanesthetized rats. Under basal conditions, plasma AVP and osmolality were relatively constant, averaging 2.3+/-0.9 (SD) pg/ml and 294+/-1.4 mosmol/kg, respectively. Fluid restriction, which increased osmolality and decreased volume, resulted in a progressive rise in plasma AVP to about 10 times basal levels after 96 h. A 2-3-fold increase in plasma AVP occurred as early as 12 h, when osmolality and volume had each changed by less than 2%. Intraperitoneal injections of hypertonic saline, which had no effect on blood volume, also produced a rise in plasma AVP that was linearly correlated with the rise in osmolality (r > 0.9) and quantitatively similar to that found during fluid restriction (plasma AVP increased 2-4-fold with each 1% increase in osmolality). Intraperitoneal injection of polyethylene glycol, which decreased blood volume without altering osmolality, also increased plasma AVP but this response followed an exponential pattern and did not become significant until volume had decreased by 8% or more. At these levels of hypovolemia, the osmoregulatory system continued to function but showed a lower threshold and increase sensitivity to osmotic stimulation. We conclude that AVP secretion is regulated principally by blood osmolality but that the responsiveness of this mechanism may be significantly altered by modest changes in blood volume.