Search

Background The biological processes associated with postacute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (PASC) are unknown. Methods We measured soluble markers of inflammation in a SARS-CoV-2 recovery cohort at early (90 days) timepoints. We defined PASC as the presence of 1 or more coronavirus disease 2019 (COVID-19)–attributed symptoms beyond 90 days. We compared fold-changes in marker values between those with and without PASC using mixed-effects models with terms for PASC and early and late recovery time periods. Results During early recovery, those who went on to develop PASC generally had higher levels of cytokine biomarkers including tumor necrosis factor–α (1.14-fold higher mean ratio [95% confidence interval {CI}, 1.01–1.28]; P = .028) and interferon-γ–induced protein 10 (1.28-fold higher mean ratio [95% CI, 1.01–1.62]; P = .038). Among those with PASC, there was a trend toward higher interleukin 6 levels during early recovery (1.29-fold higher mean ratio [95% CI, .98–1.70]; P = .07), which became more pronounced in late recovery (1.44-fold higher mean ratio [95% CI, 1.11–1.86]; P Conclusions Persistent immune activation may be associated with ongoing symptoms following COVID-19. Further characterization of these processes might identify therapeutic targets for those experiencing PASC.

BACKGROUNDShortness of breath, chest pain, and palpitations occur as post-acute sequelae of COVID-19 (PASC), but whether symptoms are associated with echocardiographic abnormalities, cardiac biomarkers, or markers of systemic inflammation remains unknown.METHODSIn a cross-sectional analysis, we assessed symptoms, performed echocardiograms, and measured biomarkers among adults >8 weeks after PCR-confirmed SARS-CoV-2 infection. We modeled associations between symptoms and baseline characteristics, echocardiographic findings, and biomarkers using logistic regression.RESULTSWe enrolled 102 participants at a median 7.2 months (IQR 4.1-9.1) following COVID-19 onset; 47 individuals reported dyspnea, chest pain, or palpitations. Median age was 52 years (range 24-86) and 41% were women. Female sex (OR 2.55, 95%CI 1.13-5.74) and hospitalization during acute infection (OR 3.25, 95%CI 1.08-9.82) were associated with symptoms. IgG antibody to SARS-CoV-2 receptor binding domain (OR 1.38 per doubling, 95%CI 1.38-1.84) and high-sensitivity C-reactive protein (OR 1.31 per doubling, 95%CI 1.00-1.71) were associated with symptoms. Regarding echocardiographic findings, 4/47 (9%) with symptoms had pericardial effusions compared to 0/55 without symptoms (p=0.038); those with pericardial effusions had a median 4 symptoms compared to 1 without (pCONCLUSIONSAmong adults in the post-acute phase of SARS-CoV-2 infection, SARS-CoV-2 RBD antibodies, markers of inflammation and, possibly, pericardial effusions are associated with cardiopulmonary symptoms. Investigation into inflammation as a mechanism underlying PASC is warranted.FUNDINGThis work was supported by the UCSF Division of Cardiology at Zuckerberg San Francisco General, and the National Institutes of Health/National Heart Lung Blood Institute and National Institute of Allergy and Infectious Diseases. MSD is supported by NIH 5K12HL143961. MJP is supported on NIH T32 AI60530-12. JDK is supported by NIH K23AI135037. TJH is supported by NIH/NIAID 3R01A1141003-03S1. PYH is supported by NIH/NAID 2K24AI112393-06. This publication was supported by the National Center for Advancing Translational Sciences, National Institutes of Health, through UCSF-CTSI Grant Number UL1TR001872. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH.GRAPHICAL ABSTRACT

BACKGROUNDAs the coronavirus disease 2019 (COVID-19) pandemic continues and millions remain vulnerable to infection with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), attention has turned to characterizing post-acute sequelae of SARS-CoV-2 infection (PASC).METHODSFrom April 21 to December 31, 2020, we assembled a cohort of consecutive volunteers who a) had documented history of SARS-CoV-2 RNA-positivity; b) were ≥ 2 weeks past onset of COVID-19 symptoms or, if asymptomatic, first test for SARS-CoV-2; and c) were able to travel to our site in San Francisco. Participants learned about the study by being identified on medical center-based registries and being notified or by responding to advertisements. At 4-month intervals, we asked participants about physical symptoms that were new or worse compared to the period prior to COVID-19, mental health symptoms and quality of life. We described 4 time periods: 1) acute illness (0-3 weeks), 2) early recovery (3-10 weeks), 3) late recovery 1 (12-20 weeks), and 4) late recovery 2 (28-36 weeks). Blood and oral specimens were collected at each visit.RESULTSWe have, to date, enrolled 179 adults. During acute SARS-CoV-2 infection, 10 had been asymptomatic, 125 symptomatic but not hospitalized, and 44 symptomatic and hospitalized. In the acute phase, the most common symptoms were fatigue, fever, myalgia, cough and anosmia/dysgeusia. During the post-acute phase, fatigue, shortness of breath, concentration problems, headaches, trouble sleeping and anosmia/dysgeusia were the most commonly reported symptoms, but a variety of others were endorsed by at least some participants. Some experienced symptoms of depression, anxiety, and post-traumatic stress, as well as difficulties with ambulation and performance of usual activities. The median visual analogue scale value rating of general health was lower at 4 and 8 months (80, interquartile range [IQR]: 70-90; and 80, IQR 75-90) compared to prior to COVID-19 (85; IQR 75-90). Biospecimens were collected at nearly 600 participant-visits.CONCLUSIONAmong a cohort of participants enrolled in the post-acute phase of SARS-CoV-2 infection, we found many with persistent physical symptoms through 8 months following onset of COVID-19 with an impact on self-rated overall health. The presence of participants with and without symptoms and ample biological specimens will facilitate study of PASC pathogenesis. Similar evaluations in a population-representative sample will be needed to estimate the population-level prevalence of PASC.

We aimed to characterize the variability in the illness experience and recovery process from COVID-19. We conducted in-depth individual interviews with participants enrolled in the Long-term Immunological Impact of Novel Coronavirus (LIINC) cohort study in San Francisco, California from June through October of 2020. Participants were adults who had a previously confirmed positive SARV-CoV-2 nucleic acid amplification test result, had recovered or were recovering from acute infection, and underwent serial evaluations at our clinical research center. We purposefully sampled 24 English- and Spanish-speaking adults with asymptomatic, mild and severe symptomatic infection, including those who were hospitalized, and those with HIV co-infection. Half of our sample (50.0%) identified as Latinx/Hispanic and most of the participants were men (62.5%). We used thematic analysis to characterize the illness experience, recovery process, and mental health impact of experiencing COVID-19 and present clinical data for each participant. Emergent themes were: (1) across symptom profiles and severity, experiencing COVID-19 was associated with psychological distress, (2) among participants with symptomatic infection, the illness experience was characterized by uncertainty in terms of managing symptoms and recovery, and (3) despite wide-ranging illness experiences, participants shared many common characteristics, including health information-seeking behavior facilitated by access to medical care, and uncertainty regarding the course of their illness and recovery. COVID-19 was associated with elevated levels of psychological distress, regardless of symptoms.

Antibody detection of prior SARS-CoV-2 infection depends on severity, assay, and timing with implications for serosurveillance., Interpretation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serosurveillance studies is limited by poorly defined performance of antibody assays over time in individuals with different clinical presentations. We measured antibody responses in plasma samples from 128 individuals over 160 days using 14 assays. We found a consistent and strong effect of disease severity on antibody magnitude, driven by fever, cough, hospitalization, and oxygen requirement. Responses to spike protein versus nucleocapsid had consistently higher correlation with neutralization. Assays varied substantially in sensitivity during early convalescence and time to seroreversion. Variability was dramatic for individuals with mild infection, who had consistently lower antibody titers, with sensitivities at 6 months ranging from 33 to 98% for commercial assays. Thus, the ability to detect previous infection by SARS-CoV-2 is highly dependent on infection severity, timing, and the assay used. These findings have important implications for the design and interpretation of SARS-CoV-2 serosurveillance studies.

A detailed understanding of long-term SARS-CoV-2-specific T cell responses and their relationship to humoral immunity and markers of inflammation in diverse groups of individuals representing the spectrum of COVID-19 illness and recovery is urgently needed. Data are also lacking as to whether and how adaptive immune and inflammatory responses differ in individuals that experience persistent symptomatic sequelae months following acute infection compared to those with complete, rapid recovery. We measured SARS-CoV-2-specific T cell responses, soluble markers of inflammation, and antibody levels and neutralization capacity longitudinally up to 9 months following infection in a diverse group of 70 individuals with PCR-confirmed SARS-CoV-2 infection. The participants had varying degrees of initial disease severity and were enrolled in the northern California Long-term Impact of Infection with Novel Coronavirus (LIINC) cohort. Adaptive T cell responses remained remarkably stable in all participants across disease severity during the entire study interval. Whereas the magnitude of the early CD4+ T cell immune response is determined by the severity of initial infection (participants requiring hospitalization or intensive care), pre-existing lung disease was significantly associated with higher long-term SARS-CoV2-specific CD8+ T cell responses, independent of initial disease severity or age. Neutralizing antibody levels were strongly correlated with SARS-CoV-2-specific CD4+ T but not CD8+ T cell responses. Importantly, we did not identify substantial differences in long-term virus-specific T cell or antibody responses between participants with and without COVID-19-related symptoms that persist months after initial infection.

We describe severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T cell responses, soluble markers of inflammation, and antibody levels and neutralization capacity longitudinally in 70 individuals with PCR-confirmed SARS-CoV-2 infection. Participants represent a spectrum of illness and recovery, including some with persistent viral shedding in saliva and many experiencing post-acute sequelae of SARS-CoV-2 infection (PASC). T cell responses remain stable for up to 9 months. Whereas the magnitude of early CD4+ T cell immune responses correlates with severity of initial infection, pre-existing lung disease is independently associated with higher long-term SARS-CoV-2-specific CD8+ T cell responses. Among participants with PASC 4 months following coronavirus disease 2019 (COVID-19) symptom onset, we observe a lower frequency of CD8+ T cells expressing CD107a, a marker of degranulation, in response to Nucleocapsid (N) peptide pool stimulation, and a more rapid decline in the frequency of N-specific interferon-γ-producing CD8+ T cells. Neutralizing antibody levels strongly correlate with SARS-CoV-2-specific CD4+ T cell responses., Graphical abstract, CD4+ and CD8+ T cell responses following natural infection with COVID-19 are stable over 8 months. Individuals with PASC demonstrate a lower frequency of CD8+ T cells expressing CD107a, a marker of degranulation, and a more rapid decline in the frequency of N-specific interferon-γ-producing CD8+ T cells.

Background and aimsDietary fructose may play a role in the pathogenesis of metabolic syndrome (MetS). In a recently published study of obese children with MetS, we showed that isocaloric fructose restriction reduced fasting triglyceride (TG) and LDL-cholesterol (LDL-C). In these ancillary analyses, we tested the hypothesis that these effects were also accompanied by improved quantitative and qualitative changes in LDL and HDL subclasses and their apolipoproteins; as well as change in VLDL, particularly apoC-III.MethodsObese children with MetS (n=37) consumed a diet that matched self-reported macronutrient composition for nine days, with the exception that dietary fructose was reduced from 11.7±4.0% to 3.8±0.5% of daily calories and substituted with glucose (in starch). Participants underwent fasting biochemical analyses on Days 0 and 10. HDL and LDL subclasses were analyzed using the Lipoprint HDL and LDL subfraction analysis systems from Quantimetrix.ResultsSignificant reductions in apoB (78±24 vs. 66±24mg/dl) apoC-III (8.7±3.5 vs. 6.5±2.6mg/dl) and apoE (4.6±2.3 vs. 3.6±1.1mg/dl), all p&nbsp

Objective: Dietary fructose is implicated in metabolic syndrome, but intervention studies are confounded by positive caloric balance, changes in adiposity, or artifactually high amounts. This study determined whether isocaloric substitution of starch for sugar would improve metabolic parameters in Latino (n 527) and African-American (n 516) children with obesity and metabolic syndrome. Methods: Participants consumed a diet for 9 days to deliver comparable percentages of protein, fat, and carbohydrate as their self-reported diet; however, dietary sugar was reduced from 28% to 10% and substituted with starch. Participants recorded daily weights, with calories adjusted for weight maintenance. Participants underwent dual-energy X-ray absorptiometry and oral glucose tolerance testing on Days 0 and 10. Biochemical analyses were controlled for weight change by repeated measures ANCOVA. Results: Reductions in diastolic blood pressure (25 mmHg; P 50.002), lactate (20.3 mmol/L; P

Consumption of high-fructose diets promotes hepatic fatty acid synthesis (de novo lipogenesis [DNL]) and an atherogenic lipid profile. It is unclear whether these effects occur independent of positive energy balance and weight gain.We compared the effects of a high-fructose, (25% of energy content) weight-maintaining diet to those of an isocaloric diet with the same macronutrient distribution but in which complex carbohydrate (CCHO) was substituted for fructose.Eight healthy men were studied as inpatients for consecutive 9-day periods. Stable isotope tracers were used to measure fractional hepatic DNL and endogenous glucose production (EGP) and its suppression during a euglycemic-hyperinsulinemic clamp. Liver fat was measured by magnetic resonance spectroscopy.Weight remained stable. Regardless of the order in which the diets were fed, the high-fructose diet was associated with both higher DNL (average, 18.6 ± 1.4% vs 11.0 ± 1.4% for CCHO; P = .001) and higher liver fat (median, +137% of CCHO; P = .016) in all participants. Fasting EGP and insulin-mediated glucose disposal did not differ significantly, but EGP during hyperinsulinemia was greater (0.60 ± 0.07 vs 0.46 ± 0.06 mg/kg/min; P = .013) with the high-fructose diet, suggesting blunted suppression of EGP.Short-term high-fructose intake was associated with increased DNL and liver fat in healthy men fed weight-maintaining diets.

Background & Aims Consumption of sugar is associated with obesity, type 2 diabetes mellitus, nonalcoholic fatty liver disease, and cardiovascular disease. The conversion of fructose to fat in liver (de novo lipogenesis [DNL]) may be a modifiable pathogenetic pathway. We determined the effect of 9 days of isocaloric fructose restriction on DNL, liver fat, visceral fat (VAT), subcutaneous fat, and insulin kinetics in obese Latino and African American children with habitual high sugar consumption (fructose intake >50 g/d). Methods Children (9−18 years old; n = 41) had all meals provided for 9 days with the same energy and macronutrient composition as their standard diet, but with starch substituted for sugar, yielding a final fructose content of 4% of total kilocalories. Metabolic assessments were performed before and after fructose restriction. Liver fat, VAT, and subcutaneous fat were determined by magnetic resonance spectroscopy and imaging. The fractional DNL area under the curve value was measured using stable isotope tracers and gas chromatography/mass spectrometry. Insulin kinetics were calculated from oral glucose tolerance tests. Paired analyses compared change from day 0 to day 10 within each child. Results Compared with baseline, on day 10, liver fat decreased from a median of 7.2% (interquartile range [IQR], 2.5%−14.8%) to 3.8% (IQR, 1.7%−15.5%) ( P 3 (IQR, 85−145 cm 3 ) to 110 cm 3 (IQR, 84–134 cm 3 ) ( P P P Conclusions Short-term (9 days) isocaloric fructose restriction decreased liver fat, VAT, and DNL, and improved insulin kinetics in children with obesity. These findings support efforts to reduce sugar consumption. ClinicalTrials.gov Number: NCT01200043.

Background: Total body volume (TBV), with the exclusion of internal air voids, is necessary to quantify body composition in Lohman's 4-compartment (4C) model. Objective: This investigation sought to derive a novel, TBV measure with the use of only dual-energy X-ray absorptiometry (DXA) attenuation values for use in Lohman's 4C body composition model. Design: Pixel-specific masses and volumes were calculated from low- and high-energy attenuation values with the use of first principle conversions of mass attenuation coefficients. Pixel masses and volumes were summed to derive body mass and total body volume. As proof of concept, 11 participants were recruited to have 4C measures taken: DXA, air-displacement plethysmography (ADP), and total body water (TBW). TBV measures with the use of only DXA (DXA-volume) and ADP-volume measures were compared for each participant. To see how body composition estimates were affected by these 2 methods, we used Lohman's 4C model to quantify percentage fat measures for each participant and compared them with conventional DXA measures. Results: DXA-volume and ADP-volume measures were highly correlated (R2 = 0.99) and showed no statistically significant bias. Percentage fat by DXA volume was highly correlated with ADP-volume percentage fat measures and DXA software-reported percentage fat measures (R2 = 0.96 and R2 = 0.98, respectively) but were slightly biased. Conclusions: A novel method to calculate TBV with the use of a clinical DXA system was developed, compared against ADP as proof of principle, and used in Lohman's 4C body composition model. The DXA-volume approach eliminates many of the inherent inaccuracies associated with displacement measures for volume and, if validated in larger groups of participants, would simplify the acquisition of 4C body composition to a single DXA scan and TBW measure.

In light of current interest in recombinant human growth hormone (GH) as a treatment for fat distribution abnormalities, we retrospectively evaluated regional changes in fat and lean body mass in a subset of subjects who participated in randomized, double-blind, placebo-controlled trials of GH for treatment of wasting. Treatment with a pharmacologic dose of GH (0.1 mg/kg/day) resulted in significant and sustained increases in lean body mass and losses of fat in both the trunk and appendicular regions.

To determine whether HIV infection, the wasting syndrome, or nucleoside analog reverse transcriptase inhibitor (NRTI) or protease inhibitor (PI) therapy uniquely affect fat distribution in men, we performed manual regional analysis of total, appendicular, trunk, and central abdominal fat measured by dual-energy X-ray absorptiometry (DEXA). Five groups of study subjects were identified for this cross-sectional analysis: HIV-negative controls (HIV-; N = 44) and four groups of HIV-positive subjects: antiretroviral (ARV)-naive or with limited prior use of NRTIs (ARV-; N = 23); on NRTIs for > or =6 months but PI-naive (NRTI; N = 30); on an NRTI/PI regimen for > or =6 months but with no complaints of abnormal fat distribution (NRTI/PI; N = 26); and those on NRTIs but PI-naive with the wasting syndrome (NRTI/WS; N = 40). Total, appendicular, trunk, and central abdominal fat was significantly lower in NRTI/WS. The ratio of trunk fat to appendicular fat was virtually identical in HIV- and ARV-. This ratio was significantly higher in the NRTI, NRTI/PI, and NRTI/WS groups, and values in these three groups were similar. These cross-sectional data suggest that HIV-infected men receiving NRTIs have an altered pattern of fat distribution, compared with HIV-negative men and HIV-positive men who are not receiving antiretroviral therapy. This effect was independent of the concomitant use of a PI or a diagnosis of the wasting syndrome. We saw no evidence of a unique effect of HIV infection per se on regional fat distribution. Although the fat ratio is increasingly employed, its physiologic significance is unclear. Our results, which have been obtained retrospectively, are intended to provide the impetus for prospective, controlled studies of the interactions among drug and host factors in the development of fat distribution abnormalities.

Although protease inhibitor (PI) therapy has improved the clinical status of patients with HIV infection, concerns have arisen that such treatment may have deleterious effects on glucose control, lipid metabolism, and body fat distribution. To determine whether initiation of PI therapy uniquely affects glucose and lipid metabolism, we analyzed paired data in HIV-infected patients before and after beginning antiretroviral therapy that included a PI (PI; N = 20) or lamivudine (3TC) but no PI (3TC; N = 9); and a control group on stable regimens that included neither of these agents (CONT: N = 12). Measurements included fasting glucose; insulin; triglycerides; total, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol; HIV RNA; CD4+ lymphocytes; weight; and total and regional body composition. Neither weight nor total or regional fat content changed significantly in any group during the period of observation. Nonetheless, in patients beginning PI therapy, there were significant increases in glucose (+9+/-3 mg/dl; p = .0136), insulin (+12.2+/-4.9 U/ml; p = .023), triglycerides (+53+/-17 mg/dl; p = .0069), and total and LDL cholesterol (+32+/-11 and +18+/-5 mg/dl; p = .0082 and .0026, respectively). None of these parameters changed significantly in the 3TC or CONT groups. The PI and 3TC groups experienced comparable increases in CD4+ lymphocytes, suggesting that the observed metabolic effects may be associated with PIs uniquely, rather than improvement in clinical status. However, it is also possible that the metabolic effects of PIs are associated with more effective viral suppression, because a greater proportion of patients in the PI group achieved undetectable levels of virus. We conclude that changes in glucose and lipid metabolism are induced by PI therapy in the absence of significant changes in weight or fat distribution. Longer periods of follow-up will be required to determine the clinical significance of these changes. However, at the moment, the risks associated with these metabolic effects do not appear to outweigh improvements in survival seen with PI therapy.

Body wasting and loss of lean body mass (LBM) have been associated with increased mortality and disease progression, and reduced quality of life, in patients with human immunodeficiency virus (HIV) infection. The failure of nutritional therapies and, more recently, of effective viral suppression, to consistently restore LBM has prompted investigation of the pharmacologic use of a number of specific protein anabolic agents, including recombinant human growth hormone (rhGH), insulin-like growth factor I (rhIGF-I), and synthetic testosterone derivatives, such as nandrolone decanoate, oxandrolone, and oxymetholone. In a placebo-controlled trial, treatment with rhGH resulted in a significant and sustained increase in weight that was accompanied by an even greater increase in LBM and a decrease in fat, and improvement in treadmill work output. Preliminary data suggest that short-term rhGH treatment may be effective in mitigating weight loss in patients with secondary infections. Open-label studies of nandrolone decanoate suggest that this injectable agent also can increase weight and LBM. Two oral agents, oxandrolone and oxymetholone, can increase weight, but their effects on LBM in placebo-controlled trials have not been reported. Taken together, these studies demonstrate that HIV-infected individuals can regain weight and LBM under the proper therapeutic circumstances. The effects of reversal of wasting on survival and disease progression, long-term safety, and the potential value of these therapies in the treatment of fat redistribution remain to be determined.

In previous studies, treatment with recombinant human GH (rhGH) produced sustained increases in weight and lean body mass (LBM) and decreases in fat mass in patients with human immunodeficiency virus (HIV)-associated wasting. To evaluate the effects of chronic rhGH treatment on components of energy balance, we recruited separate subgroups of HIV-positive patients with an involuntary weight loss of 10% or more to undergo paired measurements of resting energy metabolism (n = 6) or food intake (n = 11) before and during the final week of a 3-month rhGH (0.1 mg/kg·day) treatment period. In the energy metabolism subset, resting energy expenditure (REE) and substrate oxidation rates were measured by indirect calorimetry during brief admissions to a metabolic ward. Patients in the energy intake subset prepared written 4-day food intake diaries. Body composition was measured in both groups by bioelectrical impedance analysis. Changes in weight (+2.2 ± 0.9 and +2.2 ± 0.6 kg), LBM (+3.2 ± 0.6 and +3.8 ± 0.5 kg), an...

Preoperative assessment of bone mineral density (BMD) via dual X-ray absorptiometry (DEXA) has been shown to help determine the need for screw augmentation, particularly in the pedicle. However, patients frequently present without preoperative DEXA scans, especially in trauma situations. We developed a “smart” probe for intra-operative assessment of local bone strength in the pedicle. A standard ball tip probe was instrumented with an in-line load cell and was used to test the bone strength of fresh-frozen human cadaveric lumbar spine. Local bone crush strength was assessed using the probe at five locations within the centrum and the pedicle. The contralateral pedicle was outfitted with a standard pedicle screw and insertion torque and pull-out force of the screw were measured. Correlation was found between PS-centrum (probe strength-centrum) and screw pull-out strength (adj. R2 = 0.42). A stepwise linear regression revealed that when considering BMD, insertion torque, and PS-centrum, pull-out strength could be predicted based on PS-centrum and insertion torque (adj. R2 = 0.51, p

HIV-infected individuals are at risk for decreased bone mineral density (BMD). The known risk factors for bone loss do not fully explain the increased risk in this population. There is emerging evidence that leptin, a hormone secreted by adipocytes, plays an important role in bone metabolism. Several studies have assessed the relationship between leptin and bone density in healthy adults, but there are few such studies in HIV-infected individuals. Furthermore, HIV infected individuals on antiretroviral therapy are at increased risk for altered fat distribution, which may impact the relationship between leptin and BMD. In a cross-sectional analysis of data in 107 HIV-infected men, we determined whether serum leptin levels were associated with whole-body BMD and bone mineral content measured by dual-energy X-ray absorptiometry (DEXA), after adjusting for confounders including body fat distribution. We found an inverse association between leptin and bone density in those with peripheral lipoatrophy, defined objectively as 3 kg appendicular fat. This result suggests that fat distribution may modify the relationship between leptin and bone density.

Context: HIV-infected patients on antiretroviral therapy are at increased risk for excess visceral adiposity and insulin resistance. Treatment with GH decreases visceral adiposity but worsens glucose metabolism. IGF-I, which mediates many of the effects of GH, improves insulin sensitivity in HIV-negative individuals. Objective: Our objective was to determine whether IGF-I, complexed to its major binding protein, IGF-binding protein-3 (IGFBP-3), improves glucose metabolism and alters body fat distribution in HIV-infected patients with abdominal obesity and insulin resistance. Methods: We conducted a pilot, open-label study in 13 HIV-infected men with excess abdominal adiposity and insulin resistance to assess the effect of 3 months of treatment with IGF-I/IGFBP-3 on glucose metabolism and fat distribution. Glucose metabolism was assessed by oral glucose tolerance test and hyperinsulinemic-euglycemic clamp. Endogenous glucose production (EGP), gluconeogenesis, whole-body lipolysis, and de novo lipogenesis (DNL) were measured with stable isotope infusions. Body composition was assessed by dual-energy x-ray absorptiometry and abdominal computed tomography scan. Results: Glucose tolerance improved and insulin-mediated glucose uptake increased significantly during treatment. EGP increased under fasting conditions, and suppression of EGP by insulin was blunted. Fasting triglycerides decreased significantly in association with a decrease in hepatic DNL. Lean body mass increased and total body fat decreased, whereas visceral adipose tissue did not change. Conclusions: Treatment with IGF-I/IGFBP-3 improved whole-body glucose uptake and glucose tolerance, while increasing hepatic glucose production. Fasting triglycerides improved, reflecting decreased DNL, and visceral adiposity was unchanged.

Failure of the pedicle screw at the screw-bone interface is a common clinical problem, particularly in the setting of osteoporosis, and poses reconstructive challenges for all orthopaedic surgeons. Pedicle screw failure through screw loosing and pull-out is highly correlated with bone mineral density (BMD) and local bone quality [1]. Pre-operative assessment of BMD via dual x-ray absorptiometry (DEXA) has been shown to help determine the need for screw augmentation. However, patients frequently present without pre-operative DEXA scans. Furthermore, DEXA scans provide a measure of general bone quality, but do not necessarily reflect segmental and local variation in the spine [2]. The ability to assess BMD on a per-vertebrae basis intra-operatively would assist with surgical decisions regarding screw sizing, placement and augmentation.Copyright © 2010 by ASME

The distal radius is a common site of fracture with volar plates and screws as the current clinical practice for fracture fixation [1]. Local measurements of bone quality at the sites of screw insertion aid in providing the most stable fixation with the least amount of hardware, minimizing the risk of construct failure and irritation to soft tissue [2, 3]. The clinical standard for pre-operative bone mineral density (BMD) assessment uses dual x-ray absorptiometry (DEXA). However, DEXA scans provide global BMD values and cannot accurately predict variations in BMD within a given anatomical site [4]. Furthermore, patients frequently present without a pre-operative DEXA scan, so intra-operative assessment would be ideal. We developed a simple sensor system that would be appropriate for assessing local BMD intra-operatively. The system consists of a “smart” Weber clamp instrumented with a single uniaxial strain gage that provides real-time feedback regarding the local BMD.

The bone mineral density (BMD) in a given fracture site may affect the outcome of fracture fixation. Low BMD values, such as those occurring in osteoporotic bone, can determine the fixation method and the postoperative care. Evaluation of the BMD is either done subjectively during surgery or by a preoperative measurement. The technique most commonly used to measure BMD preoperatively is dual-energy X-ray absorptiometry (DEXA). DEXA scans have been shown to be site specific [1,2] and therefore may be inaccurate in determining local BMD at the fixation site. Furthermore, in trauma cases, patients frequently do not present with a pre-operative DEXA scan; and the ideal method of assessment would be intraoperative. Intraoperative BMD assessment could be used to guide surgical decisions such as the point of entry of a screw for a fracture plating system or use of locking versus non-locking screw-plate contruct.Copyright © 2009 by ASME

Dual-energy x-ray absorptiometry (DEXA), the technique most widely used to assess skeletal integrity, is routinely performed on cadaveric tissue to ensure that the bone mineral densities (BMD) of the test specimens are representative of the target patient population for a particular orthopaedic device [1]. It is well established that DEXA-BMD measurements are sensitive to the amount of fat and other soft tissue present in the region of interest [2]. Recognizing that the removal of perivertebral soft tissue may affect DEXA-BMD readings of in vitro cadaveric specimens, biomechanics researchers have used various “torso surrogates” to simulate the removed tissue and x-ray attenuation. These include: 1) submersion of spinal sections in a physiological saline bath, 2) surrounding spinal sections with gel-filled packs, and 3) packing rice-filled bags around spinal sections and within the internal cavity of eviscerated torsos [3, 4]. It is unknown whether these inter-study differences in technique affect in vitro DEXA measurements. Given the prevalence of soft tissue artifacts in vivo, the goal of this study is to examine the sensitivity of in vitro DEXA-BMD to the quantity and composition of soft tissue surrogates. This work is the first step in a broader study to develop a set of best practices for DEXA scanning of cadaveric tissue.Copyright © 2009 by ASME

Context: Leptin deficiency is associated with dyslipidemia and insulin resistance in animals and humans with lipoatrophy; leptin replacement ameliorates these abnormalities. Objective: The objective of the study was to evaluate the effects of leptin therapy in lipoatrophic HIV-infected patients with dyslipidemia and hypoleptinemia. Design: This was a 6-month, open-label, proof-of-principle pilot study. Setting: Metabolic ward studies were performed before and 3 and 6 months after leptin treatment. Participants: Participants included eight HIV-infected men with lipoatrophy, fasting triglycerides greater than 300 mg/dl, and serum leptin less than 3 ng/ml. Intervention: Recombinant human leptin was given by sc injection (0.01 mg/kg and 0.03 mg/kg twice daily for successive 3 month periods). Outcome Measures: Measures included fat distribution by magnetic resonance imaging and dual-energy X-ray absorptiometry; fasting lipids; insulin sensitivity by euglycemic hyperinsulinemic clamp; endogenous glucose production, gluconeogenesis, glycogenolysis, and whole-body lipolysis by stable isotope tracer studies; oral glucose tolerance testing; liver fat by proton magnetic resonance spectroscopy; and safety. Results: Visceral fat decreased by 32% (P = 0.001) with no changes in peripheral fat. There were significant decreases in fasting total (15%, P = 0.012), direct low-density lipoprotein (20%, P = 0.002), and non-high-density lipoprotein (19%, P = 0.005) cholesterol. High-density lipoprotein cholesterol increased. Triglycerides, whole-body lipolysis, and free fatty acids decreased during fasting and hyperinsulinemia. Fasting insulin decreased. Endogenous glucose production decreased during fasting and hyperinsulinemia, providing evidence of improved hepatic insulin sensitivity. Leptin was well tolerated but decreased lean mass. Conclusions: Leptin treatment was associated with marked improvement in dyslipidemia. Hepatic insulin sensitivity improved and lipolysis decreased. Visceral fat decreased with no exacerbation of peripheral lipoatrophy. Results from this pilot study suggest that leptin warrants further study in patients with HIV-associated lipoatrophy.

Summary Background Enlargement of the dorsocervical fat pad ("buffalo hump") has been reported in numerous HIV-1-infected patients. Some investigators have speculated that this finding is associated with protease-inhibitor treatment. Methods Between June, 1995, and October, 1997, we studied eight HIV-1-infected men who had developed a buffalo hump while otherwise stable on antiretroviral therapy. Measurement of 24 h urinary free cortisol excretion and an overnight low-dose dexamethasone suppression test were done to screen for Cushing's syndrome. In one patient, plasma cortisol concentrations were measured every 4 h for 24 h to assess the circadian rhythm of cortisol. Results of total and regional body-composition analysis by dual-energy X-ray absorptiometry, and glucose, cholesterol, triglyceride, and cortisol concentrations were compared with those obtained in a control population of 15 HIV-1-positive men whose age, body-mass index (BMI), and CD4-lymphocyte count were within the range of values in the eight study patients. Findings The eight patients with a buffalo hump were clinically stable on various antiretroviral regimens, four of which included a protease inhibitor. No other signs of Cushing's syndrome were observed, and plasma cortisol values did not differ significantly from those of controls. 24 h urinary free cortisol excretion was normal in seven patients and slightly raised in one (248 nmoles). In this patient, a repeat 24 h urinary free cortisol was 175 nmoles and plasma cortisol concentrations over 24 h showed a normal circadian pattern (nadir 83 nmol/L at 2400 h). All eight patients had normal suppression of cortisol values after dexamethasone 1 mg (plasma cortisol less than 83 nmol/L). When compared with HIV-1-positive controls, men with a buffalo hump had a significantly greater proportion of fat in the trunk region, suggesting central fat accumulation. Triglyceride but not cholesterol values were higher in the patients than in controls but this difference was not significant. Fasting glucose values did not differ significantly. Interpretation The development of a buffalo hump cannot be attributed to hypercortisolism in these eight men. Furthermore, its occurrence is not unique to patients on protease inhibitors. Although the mechanism for dorsocervical fat accumulation is unclear, we speculate that regional abnormalities in lipogenesis and lipolysis occur, possibly influenced by the hormonal and metabolic changes seen with HIV-1 infection and its treatment.

Body wasting is an increasingly prevalent AIDS-defining condition and an independent risk factor for mortality in patients infected with HIV. Largely on the basis of studies conducted early in the epidemic, HIV-associated wasting has been assumed to feature a disproportionate loss of lean tissue. We report the results obtained from cross-sectional and longitudinal studies that differ from these earlier observations. In a cross-sectional analysis, weight and body composition determined by dual-energy x-ray absorptiometry and bioelectrical impedance analysis in 32 HIV-infected men with documented weight loss ofor = 10% were compared to those in 46 HIV-positive men without significant weight loss and 32 HIV-negative controls. Fat, lean body mass (LBM), and body cell mass (BCM) were significantly lower in men with weight loss relative to controls (p0.001 for fat and BCM; p = 0.01 for LBM). Two thirds of the difference in weight was fat. For the longitudinal analysis, the composition of weight lost over time was evaluated in paired measurements in men grouped by body fat content (15% or15%, n = 10 per group). Weight loss in patients with baseline fat of more than 15% was only 16% LBM, but the composition of weight lost in men with baseline fat of less than 15% was 70% LBM. We conclude that progressive decreases in fat and lean tissue occur in men with HIV infection, with the composition of weight lost depending on baseline fat content. These results argue against the widely held notion that HIV-associated wasting is characterized by preservation of fat at the expense of lean tissue.

To the Editor: Resting energy expenditure has been variably reported as increased,1 inconsistently elevated,2 and decreased3 in patients with human immunodeficiency virus (HIV) infection. The deter...