The role of postoperative radiotherapy for thymomas: a multicentric retrospective evaluation from three Italian centers and review of the literature

BackgroundThymoma is a rare mediastinal neoplasia. Surgery is the backbone of the treatment, but the role of postoperative radiotherapy (PORT) remains controversial. We aimed to obtain data on survival and safety in patients treated with PORT in three different Italian institutions.MethodsWe retrospectively analyzed 183 consecutive patients who underwent surgery from 1981 to 2015. According to the Masaoka-Koga staging system, 39.3%, 32.7%, 18.6% and 9.8% patients were in stage I, II, III and IV of disease, respectively. PORT was indicated in 114 patients (62.3%), while 69 subjects underwent surgery alone. Complete resection was obtained in 68 patients who underwent PORT. Adverse events (AEs) were graded according to CTCAE v4.0. We analyzed the recent literature to describe the current reports on PORT for resected thymoma.ResultsMean follow-up was 130 months (range, 3–417 months). Overall survival (OS) at 1-, 5- and 10-year from surgery was 98.3%, 90.2% and 69.7% respectively. One-, 5- and 10-year disease specific survival (DSS) was 98.9%, 92.3% and 89.8% respectively. Disease free survival (DFS) at 1, 5 and 10 years from surgery was 96.7%, 88.3% and 82.8% respectively. Univariate analysis showed that complete resection, cell histology A-AB-B1 and stages I–II were significant predictors of better DSS and DFS. Multivariate analysis showed that sex, R0 margins and WHO histology was independent prognostic factors. Among patients treated with PORT, a trend towards better OS was evident with Masaoka stage I–II (P=0.09). Patients with R0 margins treated with PORT showed better OS and DSS (P=0.05). No differences in DSS for performance status (P=0.70), WHO histology (P=0.19), paraneoplastic syndrome (P=0.23) and surgical procedure (P=0.53) were evident. Patients treated with PORT had a higher level of acute AEs compared to surgery alone, but none of these was graded ≥3.ConclusionsOur results confirmed that patients with incompletely resected thymoma had the worst OS and DSS. High grade acute toxicity was not different between PORT and surgery alone. Other trials reported a significant benefit in OS, DSS and DFS in stage IIb–IV thymoma treated with PORT.     

Differential Muscle Hypertrophy Is Associated with Satellite Cell Numbers and Akt Pathway Activation Following Activin Type IIB Receptor Inhibition in Mtm1 p.R69C Mice

X-linked myotubular myopathy is a congenital myopathy caused by deficiency of myotubularin. Patients often present with severe perinatal weakness, requiring mechanical ventilation to prevent death from respiratory failure. We recently reported that an activin receptor type IIB inhibitor produced hypertrophy of type 2b myofibers and modest increases of strength and life span in the severely myopathic Mtm1δ4 mouse model of X-linked myotubular myopathy. We have now performed a similar study in the less severely symptomatic Mtm1 p.R69C mouse in hopes of finding greater treatment efficacy. Activin receptor type IIB inhibitor treatment of Mtm1 p.R69C animals produced behavioral and histological evidence of hypertrophy in gastrocnemius muscles but not in quadriceps or triceps. The ability of the muscles to respond to activin receptor type IIB inhibitor treatment correlated with treatment-induced increases in satellite cell number and several muscle-specific abnormalities of hypertrophic signaling. Treatment-responsive Mtm1 p.R69C gastrocnemius muscles displayed lower levels of phosphorylated ribosomal protein S6 and higher levels of phosphorylated eukaryotic elongation factor 2 kinase than were observed in Mtm1 p.R69C quadriceps muscle or in muscles from wild-type littermates. Hypertrophy in the Mtm1 p.R69C gastrocnemius muscle was associated with increased levels of phosphorylated ribosomal protein S6. Our findings indicate that muscle-, fiber type-, and mutation-specific factors affect the response to hypertrophic therapies that will be important to assess in future therapeutic trials.X-linked myotubular myopathy (XLMTM) is a severe form of congenital myopathy with an estimated incidence of 1:50,000 male births that most often presents with severe perinatal weakness and respiratory failure.^1,2 Many patients with XLMTM die within the first year of life despite the use of mechanical ventilation, and no treatments approved by the Food and Drug Administration are available. XLMTM is caused by mutations in the gene that encodes myotubularin (MTM1), which is a phosphoinositide phosphatase thought to be involved in endosomal trafficking, cytoskeletal organization, apoptosis, and/or maintenance of the sarcoplasmic reticulum/T-tubular system within myofibers.^3–8 Muscle biopsies from patients with XLMTM display excessively small fibers with increased numbers of fibers that contain central nuclei and central aggregation of organelles.⁹ Although the number of centrally nucleated fibers bears little relationship to a patient''s prognosis, there is a clear correlation between the degree of fiber smallness at birth and the severity of the patients'' disease.¹⁰ Two murine models of myotubularin deficiency are used, the severely symptomatic Mtm1δ4 (also referred to as Mtm1 knockout in prior studies^3,11,12) and the moderately symptomatic Mtm1 p.R69C mice,¹³ both of which display weakness and myofiber smallness and similar pathology to that seen in XLMTM.Because of the relationship between myofiber size and symptomatic severity in patients with XLMTM and in Mtm1δ4 mice, we had previously hypothesized that correction of myofiber smallness in myotubularin deficiency would greatly improve strength. Inhibitors of myostatin or nonfunctional decoys of its receptor, the activin type IIB receptor (ActRIIB), can be used to inhibit this negative regulator of myofiber size, leading to myofiber hypertrophy. Myostatin binds to (and signals through) the ActRIIB to activate the transforming growth factor-β pathway, which prevents progression through the cell cycle and down-regulates several key processes related to myofiber hypertrophy.^14,15 We recently reported a trial of ActRIIB-mFC in Mtm1δ4 mice, which produced 17% extension of life span, with transient increases in weight, forelimb grip strength, myofiber size, and myofiber hypertrophy restricted to type 2b myofibers in Mtm1δ4 animals.¹² Interestingly, ActRIIB-mFc produces hypertrophy in all muscle fiber types in wild-type (WT) mice,^12,16 which suggests that myotubularin deficiency interferes with the activation of hypertrophic pathways in oxidative fibers.We hypothesized that the transience of the therapeutic effects observed in treated Mtm1δ4 mice may have been related to the severity of the disease, so we have now repeated this study in the less severely affected Mtm1 p.R69C mouse.¹³ Surprisingly, treatment of Mtm1 p.R69C mice did not produce significant increases in animal weight or grip strength, and treatment-induced myofiber hypertrophy was only observed in the Mtm1 p.R69C gastrocnemius muscles. The ability of these muscles to respond to ActRIIB-mFC treatment correlated with treatment-induced increases in satellite cell number and several muscle-specific abnormalities of hypertrophic signaling. The main difference between treatment-responsive (gastrocnemius) and treatment-resistant (quadriceps) muscles in Mtm1 p.R69C mice was related to low levels of phosphorylated ribosomal protein 6 (p-rpS6) and high levels of eukaryotic elongation factor 2 kinase (eEF2K) in the treatment-responsive gastrocnemius muscle that were not observed in other Mtm1 p.R69C muscles or in WT mice. rpS6 and eEF2K are terminal signaling molecules of the insulinlike growth factor-1/Akt and extracellular signal-related kinase (ERK) pathways that are involved in the fine-tuning of global protein synthesis, with a role in the determination of cell size that remains unclear (reviewed in Meyuhas¹⁷). Our findings indicate that the response to hypertrophic agents does not always correlate with activities of known hypertrophic pathways, such as the Akt pathway, but unexpectedly varies both by muscle type and fiber type and in XLMTM is affected by the nature of the Mtm1 mutation. These results highlight that there is much we still do not understand about the control of muscle size and emphasize the importance of evaluating multiple muscle and fiber types in future trials of hypertrophic therapies.     

Regulation of photosystem I light harvesting by zeaxanthin

In oxygenic photosynthetic eukaryotes, the hydroxylated carotenoid zeaxanthin is produced from preexisting violaxanthin upon exposure to excess light conditions. Zeaxanthin binding to components of the photosystem II (PSII) antenna system has been investigated thoroughly and shown to help in the dissipation of excess chlorophyll-excited states and scavenging of oxygen radicals. However, the functional consequences of the accumulation of the light-harvesting complex I (LHCI) proteins in the photosystem I (PSI) antenna have remained unclarified so far. In this work we investigated the effect of zeaxanthin binding on photoprotection of PSI–LHCI by comparing preparations isolated from wild-type Arabidopsis thaliana (i.e., with violaxanthin) and those isolated from the A. thaliana nonphotochemical quenching 2 mutant, in which violaxanthin is replaced by zeaxanthin. Time-resolved fluorescence measurements showed that zeaxanthin binding leads to a previously unrecognized quenching effect on PSI–LHCI fluorescence. The efficiency of energy transfer from the LHCI moiety of the complex to the PSI reaction center was down-regulated, and an enhanced PSI resistance to photoinhibition was observed both in vitro and in vivo. Thus, zeaxanthin was shown to be effective in inducing dissipative states in PSI, similar to its well-known effect on PSII. We propose that, upon acclimation to high light, PSI–LHCI changes its light-harvesting efficiency by a zeaxanthin-dependent quenching of the absorbed excitation energy, whereas in PSII the stoichiometry of LHC antenna proteins per reaction center is reduced directly.In eukaryotic photosynthetic organisms, photosystem I (PSI) and photosystem II (PSII) comprise a core complex hosting cofactors involved in electron transport and an outer antenna system made of light-harvesting complexes (LHCs): Lhcas for PSI and Lhcbs for PSII. The core complexes bind chlorophyll a (Chl a) and β-carotene, whereas the outer antenna system, in addition to Chl a, binds chlorophyll b (Chl b) and xanthophylls. Despite their overall similarity, PSI and PSII differ in the rate at which they trap excitation energy at the reaction center (RC), with PSI being faster than PSII (1–9). They also differ in their structure (10–12). PSI is monomeric and carries its antenna moiety on only one side as a half-moon–shaped structure whose size is not modulated by growth conditions (13, 14). PSII, on the other hand, is found mainly as a dimeric core surrounded by an inner layer of antenna proteins (Lhcb4–6) and an outer layer of heterotrimeric LHCII complexes (Lhcb 1–3) whose stoichiometry varies depending on the growth conditions (7, 12, 13, 15). Acclimation to high irradiance leads to a lower number of trimers per PSII RC accompanied by loss of the monomeric Lhcb6. These slow acclimative responses regulate the excitation pressure on the PSII RC, preventing saturation of the electron transport chain (16) and the oxidative stress in high light (HL), leading to photoinhibition. The response to rapid changes in light level is managed by turning on some photoprotective mechanisms, such as the nonphotochemical quenching (NPQ) of the excess energy absorbed by PSII (16), which is activated by the acidification of the thylakoid lumen and protonation of the trigger protein PsbS or LhcSR. Low luminal pH also activates violaxanthin de-epoxidase (VDE), catalyzing the de-epoxidation of the xanthophyll violaxanthin to zeaxanthin (17, 18), a scavenger of reactive oxygen species (ROS) produced by excess light (9, 13). Zeaxanthin also enhances NPQ, as observed in vivo by a decrease of PSII fluorescence (19). The short-term effects of exposure to HL on PSI have been disregarded thus far. Because of its rapid photochemistry, PSI shows low fluorescence emission, implying a low ¹Chl* concentration and a low probability that chlorophyll triplet states will be formed by intersystem crossing. This characteristic suggests that the formation of oxygen singlet excited states (¹O*₂) is reduced and that NPQ phenomena in photoprotection are less relevant in PSI (20, 21). Nevertheless, several reports have shown that, especially in the cold (22–29), PSI can exhibit photo-inhibition, with its Lhca proteins being the primary target (24, 30). Upon synthesis in HL, zeaxanthin binding could be traced to two different types of binding site. One, designated “V1,” is located in the periphery of LHCII trimers (31–33). The second, designated “L2,” has an inner location in the dimeric Lhca1–4 and the monomeric Lhcb4–6 members of the LHC family (34–37). Experimental determination of the efficiency of the violaxanthin-to-zeaxanthin exchange yielded a maximal score in the Lhca3 and Lhca4 subunits (24, 25). Interestingly, Lhca1/4 and Lhca2/3 are bound to the PSI core as dimers that can be isolated in fractions identified as “LHCI-730” and “LHCI-680,” respectively, both accumulating zeaxanthin to a de-epoxidation index of ∼0.2 (20, 38). Lhca3 and Lhca4 carry low-absorption-energy chlorophyll forms known as “red forms” (39, 40) that are responsible for the red-shifted PSI emission peak at 730–740 nm at 77 K. The molecular basis for red forms is an excitonic interaction of two chromophores: chlorophylls 603 and 609 located a few angstroms from the xanthophyll in site L2, which can be either violaxanthin or zeaxanthin depending on light conditions (41, 42). It is unclear whether the binding of zeaxanthin to the PSI–LHCI complex has specific physiological function(s) or is simply a result of its common origin with Lhcb proteins.The goal of this study was to understand whether zeaxanthin plays a role in PSI–LHCI photoprotection. To investigate the role of zeaxanthin bound to Lhca proteins, we analyzed the changes in antenna size and Chl a fluorescence dynamics in PSI supercomplexes binding either violaxanthin or zeaxanthin. We found a zeaxanthin-dependent regulation of PSI antenna size and an enhanced resistance to excess light upon zeaxanthin binding. These results show that dynamic changes in the efficiency of light use and in photoprotection capacity are not exclusive to PSII, as previously thought; instead, eukaryotic photosynthetic organisms modulate the function of both photosystems in a coordinated manner.     

The predictive value of heart-type fatty acid-binding protein is independent from symptom duration in normotensive patients with pulmonary embolism

Background

Heart-type fatty acid-binding protein (H-FABP) is a useful biomarker for risk stratification of patients with pulmonary embolism (PE). In patients with acute myocardial infarction, H-FABP plasma concentrations rise after 30 minutes and return to normal within 20-24 hours. We tested whether the predictive value of H-FABP is affected by the duration of symptoms prior to diagnosis in patients with PE.

Material and Methods

We prospectively studied 257 consecutive normotensive patients with confirmed symptomatic PE.

Results

Patients with acute (< 24 hours; n = 150) symptom onset presented more often with syncope (28.7% vs. 6.5%; p < 0.001) compared to patients with symptoms ≥ 24 hours (n = 107); other baseline characteristics, comorbidities, and risk factors were distributed equally. Patients with an adverse 30-day outcome (6.6%) had higher H-FABP levels (11.84 [3.57-19.62] ng/ml) compared to patients with a favorable course (3.42 [1.92-5.42] ng/ml; p < 0.001). However, the proportion of patients with H-FABP levels ≥ 6 ng/ml did not differ among patients with acute symptom onset and late presentation (p = 0.104). Only tachycardia and elevation of H-FABP were associated with an increased risk of an adverse 30-day outcome both in patients with acute symptom onset (H-FABP: OR, 5.8; 95% CI, 1.4-24.5; p = 0.016; tachycardia: 7.0 [1.4-36.0]; p = 0.018) and late presentation (H-FABP: 9.3 [2.0-43.2]; p = 0.004 and tachycardia: 12.3 [1.5-103.6]; p = 0.021). The prognostic value could further be improved by the use of a simple H-FABP-based clinical prediction score.

Conclusions

Our findings indicate that H-FABP is a useful biomarker for risk stratification of normotensive patients with PE regardless of symptom duration prior to diagnosis.     

Long‐Term Trajectories of PTSD in Vietnam‐Era Veterans: The Course and Consequences of PTSD in Twins

We estimated the temporal course of posttraumatic stress disorder (PTSD) in Vietnam‐era veterans using a national sample of male twins with a 20‐year follow‐up. The complete sample included those twins with a PTSD diagnostic assessment in 1992 and who completed a DSM‐IV PTSD diagnostic assessment and a self‐report PTSD checklist in 2012 (n = 4,138). Using PTSD diagnostic data, we classified veterans into 5 mutually exclusive groups, including those who never had PTSD, and 4 PTSD trajectory groups: (a) early recovery, (b) late recovery, (c) late onset, and (d) chronic. The majority of veterans remained unaffected by PTSD throughout their lives (79.05% of those with theater service, 90.85% of those with nontheater service); however, an important minority (10.50% of theater veterans, 4.45% of nontheater veterans) in 2012 had current PTSD that was either late onset (6.55% theater, 3.29% nontheater) or chronic (3.95% theater, 1.16% nontheater). The distribution of trajectories was significantly different by theater service (p < .001). PTSD remains a prominent issue for many Vietnam‐era veterans, especially for those who served in Vietnam.     

High-level gentamicin resistance mediated by a Tn4001-like transposon in seven nonclonal hospital isolates of Streptococcus pasteurianus

We report on the first occurrence of high-level gentamicin resistance (MICs > or = 512 microg/ml) in seven clinical isolates of Streptococcus pasteurianus from Hong Kong. These seven isolates were confirmed to be the species S. pasteurianus on the basis of nucleotide sequencing of the superoxide dismutase (sodA) gene. Epidemiological data as well as the results of pulse-field gel electrophoresis analysis suggested that the seven S. pasteurianus isolates did not belong to the same clone. Molecular characterization showed that they carried a chromosomal, transposon-borne resistance gene [aac(6')Ie-aph(2')Ia] which was known to encode a bifunctional aminoglycoside-modifying enzyme. The genetic arrangement of this transposon was similar to that of Tn4001, a transposon previously recovered from Staphylococcus aureus and other gram-positive isolates. Genetic linkage with other resistance elements, such as the ermB gene for erythromycin resistance, was not evident. On the basis of these findings, we suggest that routine screening for high-level gentamicin resistance should be recommended for all clinically significant blood culture isolates. This is to avoid the inadvertent use of short-course combination therapy with penicillin and gentamicin, which may lead to the failure of treatment for endocarditis, the selection of drug-resistant Streptococcus pasteurianus and other gram-positive organisms, as well as the unnecessary usage of gentamicin, a drug with potential toxicity.     

Intra-articular knee joint effusion induces quadriceps avoidance gait patterns

OBJECTIVES: (1) To identify adaptations caused by intra-articular knee joint effusion during walking and (2) to determine if knee joint effusion may be a causative factor in promoting quadriceps avoidance gait patterns. DESIGN: Gait testing of 14 healthy individuals who underwent incremental saline injections of the knee joint capsule.Background. Gait adaptations have been reported in the literature for knee injured and rehabilitating individuals. Knee joint capsular afferent activity can influence knee joint function. METHODS: Gait analysis was employed in a pre- and post-test, repeated measures design to determine lower extremity joint kinematics, kinetics, energetics and thigh EMG adaptations due to intra-articular knee joint effusion. RESULTS: Knee effusion caused an increase in hip and knee flexion through the stance phase. Knee extensor torque, impulse and negative and positive work were diminished with increased effusion levels. Quadriceps activity decreased and hamstring activity increased due to intra-articular knee joint effusion. DISCUSSION: These adaptations cannot be attributed to an injury, surgery or rehabilitation. Thus, the results of this experiment suggest knee joint capsular distention, via knee joint effusion, may be responsible for many gait adaptations reported for knee injured individuals in previous investigations. CONCLUSIONS: Knee joint effusion and the subsequent capsular distention can cause major alterations in the normal gait cycle and can be considered a causative factor promoting the acquisition of quadriceps avoidance gait patterns. RELEVANCE: This study provides reference data on the effects of intra-articular knee joint effusion on gait parameters by which future studies of injured or rehabilitating individuals can be compared.