Autoantibodies to Perilipin-1 Define a Subset of Acquired Generalized Lipodystrophy

Acquired lipodystrophy is often characterized as an idiopathic subtype of lipodystrophy. Despite suspicion of an immune-mediated pathology, biomarkers such as autoantibodies are generally lacking. Here, we used an unbiased proteome-wide screening approach to identify autoantibodies to the adipocyte-specific lipid droplet protein perilipin 1 (PLIN1) in a murine model of autoimmune polyendocrine syndrome type 1 (APS1). We then tested for PLIN1 autoantibodies in human subjects with acquired lipodystrophy with two independent severe breaks in immune tolerance (including APS1) along with control subjects using a specific radioligand binding assay and indirect immunofluorescence on fat tissue. We identified autoantibodies to PLIN1 in these two cases, including the first reported case of APS1 with acquired lipodystrophy and a second patient who acquired lipodystrophy as an immune-related adverse event following cancer immunotherapy. Lastly, we also found PLIN1 autoantibodies to be specifically enriched in a subset of patients with acquired generalized lipodystrophy (17 of 46 [37%]), particularly those with panniculitis and other features of autoimmunity. These data lend additional support to new literature that suggests that PLIN1 autoantibodies represent a marker of acquired autoimmune lipodystrophies and further link them to a break in immune tolerance.

Diagnostic Accuracy of Methods for Detection of Antibodies against Type I Interferons in Patients with Endocrine Disorders

Autoantibodies against type 1 interferons (IFN-I) are a highly specific marker for type 1 autoimmune polyglandular syndrome (APS-1). Moreover, determination of antibodies to omega-interferon (IFN-ω) and alpha2-interferon (IFN-α2) allows a short-term diagnosis in patients with isolated and atypical forms of APS-1. In this study, a comparison of three different methods, namely multiplex microarray-based, cell-based and enzyme-linked immunosorbent assays for detection of antibodies against omega-interferon and alpha2-interferon, was carried out. A total of 206 serum samples from adult patients with APS-1, APS-2, isolated autoimmune endocrine pathologies or non-autoimmune endocrine disorders, and healthy individuals were analyzed. In the APS-1 patient cohort (n = 18), there was good agreement between the results of anti-IFN-I antibody tests performed by three methods, with 100% specificity and sensitivity for microarray-based assay. Although only the cell-based assay can determine the neutralizing activity of autoantibodies, the microarray-based assay can serve as a highly specific and sensitive screening test to identify anti-IFN-I antibody positive patients.

POS1453 INTERVAL HYPOXIC-HYPEROXIC TRAINING IN REHABILITATION OF PATIENTS WITH OSTEOARTHRITIS AND POST-COVID SYNDROME

Background

Intermittent hypoxia conditioning reduces the levels of inflammatory parameters and cytokines (C-reactive protein, TNF-α, IL-4, IL-6, IL-8), increases the tolerance to acute hypoxia, the functional capacity and improves parameters of respiratory and cardiovascular systems [1–4].

Objectives

To evaluate the efficiency of the interval hypoxic-hyperoxic training (Reoxy therapy) in the rehabilitation of patients with osteoarthritis (OA) and post-COVID syndrome.

Methods

36 patients with OA (78% females, age of 43 to 68 years, generalized OA, OA of the knee or hip joints) where included in the randomized placebo-controlled study. Coronavirus infection COVID-19 were diagnosed from 12 to 26 weeks before the study. The main symptoms of post-COVID syndrome were dry cough, smell loss, breathlessness, weakness, fatigue, sleep disorders, cognitive symptoms, memory problems, anxiety, depression, headache, dizziness, joint and muscle pain. All patients were randomized into 3 groups. 13 study group patients received 10 Reoxy therapy procedures, 9 placebo group patients – 10 placebo procedures of Reoxy therapy, 14 control group patients – only standard rehabilitation. The patients of all groups underwent 2-week standard rehabilitation program: 10 procedures of electrostatic massage for muscles and periarticular tissues, 10 sessions of general magnetic therapy, 10 group sessions of physical exercises with elements of breathing exercises. All patients received NSAIDs and SYSADOA at standard dosages. Intra-articular corticosteroids was not used. The study group patients were breathing hypoxic (FiO2 13–15%) and hyperoxic (FiO2 up to 40%) gas mixture through the mask in the interval mode with biofeedback using device «ReOxy» (Ai Mediq S.A., Luxembourg). 10-min hypoxic test (FiO2 12–13%) was performed before the first and fourth procedures. The duration of 1–4 procedures was 30 min, 5–10 procedures – 40 min. The placebo procedures were performed using the mask with the atmospheric air hole. Joint pain and general health on 100-mm VAS, Lequesne and WOMAC indexes, Spielberger-Khanin anxiety test, Beck depression inventory and breathlessness on Modified Borg scale were evaluated at baseline and at 2 weeks.

Results

After 2 weeks in the study group pain on VAS decreased by 49,6% (p<0,05), Lequesne index – by 39,3% (p<0,05), WOMAC – by 1,4 times (р<0,01), anxiety level on Spielberger-Khanin test – by 40,9% (p<0,05), depression level on Beck depression inventory – by 64,1% (p<0,01), general health on VAS improved by 69,3% (р<0,01). The level of breathlessness on Modified Borg scale in the study group initially was 2,5±0,9 score (moderate – slight breathlessness). After rehabilitation in the study group the level of breathlessness decreased to 0,3±0,4 score (extremely slight – no breathlessness). In the study group there were statistically significant differences from the placebo group (р<0,05) and the control group (р<0,05) in all parameters.

Conclusion

2-week complex rehabilitation program, including interval hypoxic-hyperoxic training (Reoxy therapy), reduces pain, breathlessness, depression and anxiety, improves functional status and general health in patients with OA and post-COVID syndrome.

References

[1]Timon R, et al. Exp Gerontol 2021;152:111478.

[2]Timon R, et al. Eur Rev Aging Phys Act 2021;18(1):25.

[3]Serebrovska TV, et al. Exp Biol Med 2017;242(15):1542-52.

[4]Bestavashvili AA, et al. Front Cardiovasc Med 2021;8:700826.

Disclosure of Interests

None declared

POS1455 EFFICIENCY OF PASSIVE MECHANOTHERAPY IN COMPLEX REHABILITATION OF PATIENTS WITH OSTEOARTHRITIS

Background

Different types of physical exercises relieve pain, improve functional status and quality of life in patients with osteoarthritis (ОА) in addition to drug treatment [1–4].

Objectives

To evaluate the efficiency of robotic mechanotherapy (continuous passive motion) in the complex rehabilitation of patients with OA.

Methods

58 patients with ОА of the knee, hip, wrist and hand joints (76% females, age of 49 to 65 years, disease duration of 3 to 11 years) were included in the study and randomized into 2 groups. 28 study group patients underwent robotic passive mechanotherapy (continuous passive motion) for the knee and hip joints using «ARTROMOT K1» machine (Ormed gmbh, Germany), for the wrist and hand joints using «Kinetec Maestra hand and wrist CPM» machine (Kinetec, UK) (10 sessions for 20–25 min) in addition to the standard rehabilitation program (2 weeks). 30 control group patients received only the standard rehabilitation program, which included 10 group sessions of physical exercises for the joints for 45 min under the supervision of a trainer, 10 procedures of electrostatic massage for muscles and periarticular tissues, 10 sessions of occupational therapy for 45 min (joint protection strategies, use of assistive devices and adaptive equipment). All patients received NSAIDs and SYSADOA at standard dosages. Intra-articular corticosteroids were not used. Tender joint count, joint pain on 100-mm VAS, Lequesne and WOMAC indexes, the amplitude of flexion in the knee joint measured by goniometer, the march test (passage time of 20 meters per sec), hand grip strength measured by a dynamometer were evaluated at baseline and at 2 weeks.

Results

After 2 weeks in the study group pain on VAS decreased by 40,9% (p<0,05), tender joint count – by 38,7% (p<0,05), Lequesne index – by 1,53 times (р<0,01), WOMAC – by 1,21 times (р<0,01). In the study group the amplitude of flexion in the knee joint increased by 34,2% (p<0,05), the march test decreased by 3,5±1,2 sec (28,8%) (p<0.05), the grip strength of the more affected hand enhanced by 22,3% (p<0,05), of the less affected hand – by 18,5% (р<0,05). In the study group there were statistically significant differences from the control group in all parameters (р<0,05), excluding the grip strength of the less affected hand (р>0,05).

Conclusion

2-week complex rehabilitation program, including robotic mechanotherapy (continuous passive motion), relieves pain, improves functional ability, motor activity (march test, range of motion in the knee joint, hand grip strength) in patients with OA.

References

[1]Goh SL, et al. Sports Med 2019;49(5):743–61.

[2]Rice D, et al. J Clin Med 2019;8(11):1769.

[3]Shi-Qi Wang, et al. Geriatr Orthop Surg Rehabil 2020;11:2151459320973196.

[4]Chu-Yang Zeng, et al. Front Physiol 2021;12:94062.

Disclosure of Interests

None declared

Transborder molecular analysis of drug-resistant tuberculosis in Mongolia and Eastern Siberia, Russia

Eastern Siberia (Russia) and Mongolia are borderline regions in Asia with a high incidence of tuberculosis (TB). In this study, we investigated the transborder transmission of Mycobacterium tuberculosis with a focus on endemic and epidemic clones and drug resistance. M. tuberculosis isolates (287 from Mongolia and 754 from Russia) were collected using cross-sectional population-based surveys between 2010 and 2016. The isolates were genotyped using 24 variable number of tandem repeat (VNTR) loci and by testing of the key markers to discriminate within the Beijing genotype. All isolates were divided into 427 MIRU-types that were assigned to Lineage 2 (Beijing) and Lineage 4 (Ural, Haarlem, Latin American-Mediterranean [LAM], S, unclassified). The Beijing genotype was dominant in both countries (69% in Russia, 75% in Mongolia). However, the Beijing isolates differed significantly between the countries, in terms of the identified subtypes. LAM was the most common non-Beijing genotype (11.1% in Mongolia and 14.9% in Russia) and LAM isolates mostly belonged to the LAM-RUS branch in both countries. The MDR rate was higher in Russia than in Mongolia among newly diagnosed patients: 29.4% versus 5.6% (p < 0.001). In Mongolia, the MDR rate was similar in Beijing (29.7%) and non-Beijing (27.5%) genotypes. In Russia, a higher MDR rate was observed in (i) Beijing compared to non-Beijing (48.7% versus 38.3%, p = 0.03) and (ii) Beijing B0/W148 compared to Beijing Central Asian/Russian (63.4% versus 37.3%, p<0.001). In conclusion, the M. tuberculosis population structure in Mongolia was shaped by mainly historical interaction with China (dominance of the Beijing genotype) and Northern Eurasia (presence of the LAM-RUS branch). In contrast, the transborder transmission of M. tuberculosis since the 1990s between Mongolia and its neighbors has been negligible, and the adverse trends of MDR-TB in Russia did not impact the current situation in Mongolia. This article is protected by copyright. All rights reserved.

16S rRNA gene sequencing data of the upper respiratory tract microbiome in the SARS-CoV-2 infected patients

The SARS-CoV-2 pandemic is a big challenge for humanity. The COVID-19 severity differs significantly from patient to patient, and it is important to study the factors protecting from severe forms of the disease. Respiratory microbiota may influence the patient's susceptibility to infection and disease severity due to its ability to modulate the immune system response of the host organism.

This data article describes the microbiome dataset from the upper respiratory tract of SARS-CoV-2 positive patients from Russia. This dataset reports the microbial community profile of 335 human nasopharyngeal swabs collected between 2020-05 and 2021-03 during the first and the second epidemic waves. Samples were collected from both inpatients and outpatients in 4 cities of the Russian Federation (Moscow, Kazan, Irkutsk, Nizhny Novgorod) and sequenced using the 16S rRNA gene amplicon sequencing of V3-V4 region. Data contains information about the patient such as age, sex, hospitalization status, percent of damaged lung tissue, oxygen saturation (SpO2), respiratory rate, need for supplemental oxygen, chest computer tomography severity score, SARS-CoV-2 lineage, and also information about smoking and comorbidities.

The amplicon sequencing data were deposited at NCBI SRA as BioProject PRJNA751478.

Pregnancy Outcome in Women With APECED (APS-1): A Multicenter Study on 43 Females With 83 Pregnancies

CONTEXT

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED; also known as autoimmune polyendocrine syndrome type 1) has a severe, unpredictable course. Autoimmunity and disease components may affect fertility and predispose to maternal and fetal complications, but pregnancy outcomes remain unknown.

OBJECTIVE

To assess fetal and maternal outcomes and course of clinical APECED manifestations during pregnancy in women with APECED.

DESIGN AND SETTING

A multicenter registry-based study including 5 national patient cohorts.

PATIENTS

321 females with APECED.

MAIN OUTCOME MEASURE

Number of pregnancies, miscarriages, and deliveries.

RESULTS

Forty-three patients had altogether 83 pregnancies at median age of 27 years (range, 17-39). Sixty (72%) pregnancies led to a delivery, including 2 stillbirths (2.4%) and 5 (6.0%) preterm livebirths. Miscarriages, induced abortions, and ectopic pregnancies were observed in 14 (17%), 8 (10%), and 1 (1.2%) pregnancies, respectively. Ovum donation resulted in 5 (6.0%) pregnancies. High maternal age, premature ovarian insufficiency, primary adrenal insufficiency, or hypoparathyroidism did not associate with miscarriages. Women with livebirth had, on average, 4 APECED manifestations (range 0-10); 78% had hypoparathyroidism, and 36% had primary adrenal insufficiency. APECED manifestations remained mostly stable during pregnancy, but in 1 case, development of primary adrenal insufficiency led to adrenal crisis and stillbirth. Birth weights were normal in >80% and apart from 1 neonatal death of a preterm baby, no serious perinatal complications occurred.

CONCLUSIONS

Outcome of pregnancy in women with APECED was generally favorable. However, APECED warrants careful maternal multidisciplinary follow-up from preconceptual care until puerperium.

Preexisting autoantibodies to type I IFNs underlie critical COVID-19 pneumonia in patients with APS-1

Patients with biallelic loss-of-function variants of AIRE suffer from autoimmune polyendocrine syndrome type-1 (APS-1) and produce a broad range of autoantibodies (auto-Abs), including circulating auto-Abs neutralizing most type I interferons (IFNs). These auto-Abs were recently reported to account for at least 10% of cases of life-threatening COVID-19 pneumonia in the general population. We report 22 APS-1 patients from 21 kindreds in seven countries, aged between 8 and 48 yr and infected with SARS-CoV-2 since February 2020. The 21 patients tested had auto-Abs neutralizing IFN-α subtypes and/or IFN-ω; one had anti-IFN-β and another anti-IFN-ε, but none had anti-IFN-κ. Strikingly, 19 patients (86%) were hospitalized for COVID-19 pneumonia, including 15 (68%) admitted to an intensive care unit, 11 (50%) who required mechanical ventilation, and four (18%) who died. Ambulatory disease in three patients (14%) was possibly accounted for by prior or early specific interventions. Preexisting auto-Abs neutralizing type I IFNs in APS-1 patients confer a very high risk of life-threatening COVID-19 pneumonia at any age.

THU0571 EFFICIENCY OF COMPLEX REHABILITATION PROGRAM IN PATIENTS WITH OSTEOARTHRITIS

Background:

Rehabilitation techniques and nonpharmacologic therapies help to relieve pain and improve functional status in patients with osteoarthritis (ОА) in addition to drug treatment [1–4].

Objectives:

To evaluate the efficiency of 12-month complex rehabilitation program in patients with ОА.

Methods:

50 patients with ОА of hand, knee and ankle joints (76% females, age of 48 to 69 years, disease duration of 2 to 15 years) were included and randomized into 2 groups. All patients received non-steroidal anti-inflammatory drugs and chondroprotectors in standard doses. 26 study group patients underwent 12-months complex rehabilitation program: laser therapy of 12 to 15 min (infrared laser radiation, wavelength of 0,89 micrometers, pulse frequency of 1200 to1500 Hz) for hand, knee and ankle joints, 3 courses for 10 sessions with a mean interval of 3,3 months; 45-min dynamic exercises using gym apparatus Enraf-Nonius under the supervision of a trainer 3 times a week; 45-min exercises for hands 3 times a week; 45-min occupational therapy, 10 sessions; wrist, ankle and knee orthoses, education program (3 daily 90-min studies); balance training on the COBS-platform 3 times a week. 24 patients received only drug therapy (control). Tender and swollen joint count, joint pain on 100-mm VAS, Lequesne index, WOMAC, hand grip strength, the average powers of knee extension and ankle flexion by EN-TreeM movement analysis, symmetry index (SI) and load distribution on the COBS-platform in the different modes were evaluated at baseline and at 12 months.

Results:

After 12 month in the study group tender joint count decreased by 56,2% (р<0,01), swollen joint count – by 67,3% (р<0,01), pain on VAS - by 54,7% (р<0,01), Lequesne index – by 2,3 times (р<0,01), WOMAC – by 1,8 times (р<0,01). The grip strength of a more affected hand enhanced by 41,3% (р<0,05), of a less affected – by 43,4% (р<0,05). The average extension power of a weaker knee increased by 57,3% (р<0,01), of a stronger – by 44,2% (р<0,05). The average flexion power of a more affected ankle joint elevated by 34,9% (р<0,05), of a less affected – by 48,2% (р<0,05). The pressure on the COBS-platform of the extremity with more affected joint of the patients with ОА of knee joints increased by 11,7% (p<0,05), SI – by 12,9% (p<0,05) in the mode «habitual stand». The load on the limb with more affected joint elevated by 13,2% (p<0,05), SI – by 25% (p<0,05) in the mode «get up and sit down». The pressure on the COBS-platform of the extremity with more affected joint of the patients with ОА of ankle joints was enhanced by 14,3% (p<0,05), SI – by 18,2% (p<0,05) in the mode «habitual stand». The load on the limb with more affected joint was elevated by 12,8% (p<0,05), SI – by 20,1% (p<0,05) in the mode «tiptoe bounce (do not leave ground)». In the study group there were statistically significant differences from the control group in all parameters (р<0,05).

Conclusion:

12-month complex rehabilitation program relieves pain, improves functional ability, power of motion, balance and load distribution in patients with OA.

References:

[1]Doi T, et al. Am J Phys Med Rehabil 2008;8(4):258–69.

[2]Zhang W, et al. Osteoarthritis Cartilage 2010;18:476–99.

[3]Hochberg M, et al. Arthritis Care & Research 2012;64(4):465–74.

[4]Conaghan PG, et al. BMJ 2008;336:502–3.

Disclosure of Interests:

None declared

Pilot GWAS of caries in African-Americans shows genetic heterogeneity

BACKGROUND

Dental caries is the most common chronic disease in the US and disproportionately affects racial/ethnic minorities. Caries is heritable, and though genetic heterogeneity exists between ancestries for a substantial portion of loci associated with complex disease, a genome-wide association study (GWAS) of caries specifically in African Americans has not been performed previously.

METHODS

We performed exploratory GWAS of dental caries in 109 African American adults (age > 18) and 96 children (age 3-12) from the Center for Oral Health Research in Appalachia (COHRA1 cohort). Caries phenotypes (DMFS, DMFT, dft, and dfs indices) assessed by dental exams were tested for association with 5 million genotyped or imputed single nucleotide polymorphisms (SNPs), separately in the two age groups. The GWAS was performed using linear regression with adjustment for age, sex, and two principal components of ancestry. A maximum of 1 million adaptive permutations were run to determine empirical significance.

RESULTS

No loci met the threshold for genome-wide significance, though some of the strongest signals were near genes previously implicated in caries such as antimicrobial peptide DEFB1 (rs2515501; p = 4.54 × 10- 6) and TUFT1 (rs11805632; p = 5.15 × 10- 6). Effect estimates of lead SNPs at suggestive loci were compared between African Americans and Caucasians (adults N = 918; children N = 983). Significant (p < 5 × 10- 8) genetic heterogeneity for caries risk was found between racial groups for 50% of the suggestive loci in children, and 12-18% of the suggestive loci in adults.

CONCLUSIONS

The genetic heterogeneity results suggest that there may be differences in the contributions of genetic variants to caries across racial groups, and highlight the critical need for the inclusion of minorities in subsequent and larger genetic studies of caries in order to meet the goals of precision medicine and to reduce oral health disparities.

Identification of a genetically defined ultra-high-risk group in relapsed pediatric T-lymphoblastic leukemia

In the search for genes that define critical steps of relapse in pediatric T-cell acute lymphoblastic leukemia (T-ALL) and can serve as prognostic markers, we performed targeted sequencing of 313 leukemia-related genes in 214 patients: 67 samples collected at the time of relapse and 147 at initial diagnosis. As relapse-specific genetic events, we identified activating mutations in NT5C2 (P=0.0001, Fisher's exact test), inactivation of TP53 (P=0.0007, Fisher's exact test) and duplication of chr17:q11.2-24.3 (P=0.0068, Fisher's exact test) in 32/67 of T-ALL relapse samples. Alterations of TP53 were frequently homozygous events, which significantly correlated with higher rates of copy number alterations in other genes compared with wild-type TP53 (P=0.0004, Mann–Whitney's test). We subsequently focused on mutations with prognostic impact and identified genes governing DNA integrity (TP53, n=8; USP7, n=4; MSH6, n=4), having key roles in the RAS signaling pathway (KRAS, NRAS, n=8), as well as IL7R (n=4) and CNOT3 (n=4) to be exclusively mutated in fatal relapses. These markers recognize 24/49 patients with a second event. In 17 of these patients with mostly refractory relapse and dire need for efficient treatment, we identified candidate targets for personalized therapy with p53 reactivating compounds, MEK inhibitors or JAK/STAT-inhibitors that may be incorporated in future treatment strategies.

Anti-cytokine autoantibodies preceding onset of autoimmune polyendocrine syndrome type I features in early childhood

PURPOSE

Almost all patients with autoimmune polyendocrine syndrome (APS)-I have high titer neutralizing autoantibodies to type I interferons (IFN), especially IFN-ω and IFN-α2, whatever their clinical features and onset-ages. About 90 % also have antibodies to interleukin (IL)-17A, IL-17F and/or IL-22; they correlate with the chronic mucocutaneous candidiasis (CMC) that affects ~90 % of patients. Our aim was to explore how early the manifestations and endocrine and cytokine autoantibodies appear in young APS-I patients. That may hold clues to very early events in the autoimmunization process in these patients.

METHODS

Clinical investigations and autoantibody measurements in 13 APS-I patients sampled before age 7 years, and 3 pre-symptomatic siblings with AIRE-mutations in both alleles.

RESULTS

Antibody titers were already high against IFN-α2 and IFN-ω at age 6 months in one sibling-8 months before onset of APS-I-and also against IL-22 at 7 months in another (still unaffected at age 5 years). In 12 of the 13 APS-I patients, antibody levels were high against IFN-ω and/or IL-22 when first tested, but only modestly positive against IFN-ω in one patient who had only hypo-parathyroidism. Endocrine organ-specific antibodies were present at age 6 months in one sibling, and as early as 36 and 48 months in two of the six informative subjects.

CONCLUSION

This is the first study to collate the onset of clinical features, cytokine and endocrine autoantibodies in APS-I infants and siblings. The highly restricted early autoantibody responses and clinical features they show are not easily explained by mere loss of broad-specific self-tolerance inducing mechanisms, but hint at some more sharply focused early event(s) in autoimmunization.

Efficacy and safety of Valtropin in the treatment of short stature in girls with Turner's syndrome

Valtropin (somatropin, BioPartners and LG Life Sciences [LGLS]) is a recombinant human growth hormone (GH) preparation produced using a yeast expression system. An open single-arm phase III study was conducted to evaluate efficacy and safety at a dose of 0.16 IU/kg/day (0.053 mg/kg/day) s.c. for 12 months in the treatment of short stature in girls (n = 30, aged 2-9 years) with Turner's syndrome. The primary efficacy variable was height velocity (HV) at 12 months. Secondary efficacy variables included serum GH dependent growth factors. HV increased from 3.8 +/- 1.8 cm/yr at baseline to 9.7 +/- 1.6 cm/yr (mean +/- SD) after 12 months of treatment. Marked treatment effects were also observed on other growth parameters, serum insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3). Treatment was well tolerated with no significant adverse events. It is concluded that Valtropin is as safe and effective as other human GH preparations for the treatment of growth failure in girls with Turner's syndrome.

Localisation of the PsbH subunit in photosystem II: a new approach using labelling of His-tags with a Ni(2+)-NTA gold cluster and single particle analysis

Photosystem II core dimers were isolated from the green alga Chlamydomonas reinhardtii by Ni(2+)-affinity chromatography exploiting a 6 x His tag located at the N terminus of the PsbH protein. This protein is predicted to have a single transmembrane helix. In order to identify the location of PsbH within the photosystem II complex, the His-tagged core dimers were labelled using a Ni(2+)-NTA gold cluster and subjected to electron microscopy and image analysis. This new method enabled us to identify the location of the labelled His tag by statistical analysis of electron micrographs of the gold-labelled photosystem II complex. Comparison of these data with electron and X-ray crystallographic analysis of photosystem II indicates that the N terminus of PsbH is close to the two transmembrane helices of cytochrome b(559). Our analysis suggests that this approach is a powerful method to locate specific proteins within multisubunit complexes like photosystem II when crystallographic analysis is of insufficient resolution to directly identify amino acid side-chains. Moreover, it can be combined with cross-linking studies, and here we demonstrate that PsbH is a near neighbour of PsbX, which is consistent with the latter subunit being located close to the alpha and beta-subunits of cytochrome b(559). However, cross-linking between PsbH and PsbW was not detected despite the fact that the latter cross-linked with the alpha-subunit of cytochrome b(559).

Intracellular energetic units in red muscle cells

The kinetics of regulation of mitochondrial respiration by endogenous and exogenous ADP in muscle cells in situ was studied in skinned cardiac and skeletal muscle fibres. Endogenous ADP production was initiated by addition of MgATP; under these conditions the respiration rate and ADP concentration in the medium were dependent on the calcium concentration, and 70-80% of maximal rate of respiration was achieved at ADP concentration below 20 microM in the medium. In contrast, when exogenous ADP was added, maximal respiration rate was observed only at millimolar concentrations. An exogenous ADP-consuming system consisting of pyruvate kinase (PK; 20-40 units/ml) and phosphoenolpyruvate (PEP; 5 mM), totally suppressed respiration activated by exogenous ADP, but the respiration maintained by endogenous ADP was not suppressed by more than 20-40%. Creatine (20 mM) further activated respiration in the presence of ATP and PK+PEP. Short treatment with trypsin (50-500 nM for 5 min) decreased the apparent K(m) for exogenous ADP from 300-350 microM to 50-60 microM, increased inhibition of respiration by PK+PEP system up to 70-80%, with no changes in MgATPase activity and maximal respiration rates. Electron-microscopic observations showed detachment of mitochondria and disordering of the regular structure of the sarcomere after trypsin treatment. Two-dimensional electrophoresis revealed a group of at least seven low-molecular-mass proteins in cardiac skinned fibres which were very sensitive to trypsin and not present in glycolytic fibres, which have low apparent K(m) for exogenous ADP. It is concluded that, in oxidative muscle cells, mitochondria are incorporated into functional complexes ('intracellular energetic units') with adjacent ADP-producing systems in myofibrils and in sarcoplasmic reticulum, probably due to specific interaction with cytoskeletal elements responsible for mitochondrial distribution in the cell. It is suggested that these complexes represent the basic pattern of organization of muscle-cell energy metabolism.

Lack of dystrophin is associated with altered integration of the mitochondria and ATPases in slow-twitch muscle cells of MDX mice

The potential role of dystrophin-mediated control of systems integrating mitochondria with ATPases was assessed in muscle cells. Mitochondrial distribution and function in skinned cardiac and skeletal muscle fibers from dystrophin-deficient (MDX) and wild-type mice were compared. Laser confocal microscopy revealed disorganized mitochondrial arrays in m. gastrocnemius in MDX mice, whereas the other muscles appeared normal in this group. Irrespective of muscle type, the absence of dystrophin had no effect on the maximal capacity of oxidative phosphorylation, nor on coupling between oxidation and phosphorylation. However, in the myocardium and m. soleus, the coupling of mitochondrial creatine kinase to adenine nucleotide translocase was attenuated as evidenced by the decreased effect of creatine on the Km for ADP in the reactions of oxidative phosphorylation. In m. soleus, a low Km for ADP compared to the wild-type counterpart was found, which implies increased permeability for that nucleotide across the mitochondrial outer membrane. In normal cardiac fibers 35% of the ADP flux generated by ATPases was not accessible to the external pyruvate kinase-phosphoenolpyruvate system, which suggests the compartmentalized (direct) channeling of that fraction of ADP to mitochondria. Compared to control, the direct ADP transfer was increased in MDX ventricles. In conclusion, our data indicate that in slow-twitch muscle cells, the absence of dystrophin is associated with the rearrangement of the intracellular energy and feedback signal transfer systems between mitochondria and ATPases. As the mechanisms mediated by creatine kinases become ineffective, the role of diffusion of adenine nucleotides increases due to the higher permeability of the mitochondrial outer membrane for ADP and enhanced compartmentalization of ADP flux.

Structure of the AAA ATPase p97

p97, an abundant hexameric ATPase of the AAA family, is involved in homotypic membrane fusion. It is thought to disassemble SNARE complexes formed during the process of membrane fusion. Here, we report two structures: a crystal structure of the N-terminal and D1 ATPase domains of murine p97 at 2.9 A resolution, and a cryoelectron microscopy structure of full-length rat p97 at 18 A resolution. Together, these structures show that the D1 and D2 hexamers pack in a tail-to-tail arrangement, and that the N domain is flexible. A comparison with NSF D2 (ATP complex) reveals possible conformational changes induced by ATP hydrolysis. Given the D1 and D2 packing arrangement, we propose a ratchet mechanism for p97 during its ATP hydrolysis cycle.

Cryo-electron microscopy structure of an SH3 amyloid fibril and model of the molecular packing

Amyloid fibrils are assemblies of misfolded proteins and are associated with pathological conditions such as Alzheimer's disease and the spongiform encephalopathies. In the amyloid diseases, a diverse group of normally soluble proteins self-assemble to form insoluble fibrils. X-ray fibre diffraction studies have shown that the protofilament cores of fibrils formed from the various proteins all contain a cross-beta-scaffold, with beta-strands perpendicular and beta-sheets parallel to the fibre axis. We have determined the threedimensional structure of an amyloid fibril, formed by the SH3 domain of phosphatidylinositol-3'-kinase, using cryo-electron microscopy and image processing at 25 A resolution. The structure is a double helix of two protofilament pairs wound around a hollow core, with a helical crossover repeat of approximately 600 A and an axial subunit repeat of approximately 27 A. The native SH3 domain is too compact to fit into the fibril density, and must unfold to adopt a longer, thinner shape in the amyloid form. The 20x40-A protofilaments can only accommodate one pair of flat beta-sheets stacked against each other, with very little inter-strand twist. We propose a model for the polypeptide packing as a basis for understanding the structure of amyloid fibrils in general.

Exercise-induced changes of endorphin contents in hypothalamus, hypophysis, adrenals and blood plasma

Changes of alpha-, beta-, and gamma-endorphin contents were determined in hypothalamus, hypophysis, adrenals and blood plasma in Wistar rats. Four hours of swimming in water at 32 +/- 1 degrees C caused a decrease of the beta-endorphin content in hypophysis and hypothalamus. In adrenals, beta-endorphin did not change. Changes of alpha- and gamma-endorphins were not parallel to alterations of beta-endorphin. In blood plasma, levels of both alpha- and gamma-endorphins were elevated. After 7 days of swim training, 4 hours of swimming caused a slight increase of alpha-, beta- and gamma-endorphin levels in hypophysis as well as a pronounced increase of alpha- and beta-endorphins in adrenals. In hypothalamus, beta-endorphin content was decreased, but alpha-endorphin content was on the level of sedentary controls, gamma-endorphin content doubled. The levels of endorphins in blood were higher than after a single swimming bout. It was concluded that during acute exercise the activation of the opioid system is mainly based on the augmented release of beta-endorphin. In daily repeated exercise the production of beta-endorphin increases and exceeds the elevated release in hypophysis and adrenals.