Joseph B. Shrager

Rapid Disuse Atrophy of Diaphragm Fibers in Mechanically Ventilated Humans

BACKGROUND The combination of complete diaphragm inactivity and mechanical ventilation (for more than 18 hours) elicits disuse atrophy of myofibers in animals. We hypothesized that the same may also occur in the human diaphragm. METHODS We obtained biopsy specimens from the costal diaphragms of 14 brain-dead organ donors before organ harvest (case subjects) and compared them with intraoperative biopsy specimens from the diaphragms of 8 patients who were undergoing surgery for either benign lesions or localized lung cancer (control subjects). Case subjects had diaphragmatic inactivity and underwent mechanical ventilation for 18 to 69 hours; among control subjects diaphragmatic inactivity and mechanical ventilation were limited to 2 to 3 hours. We carried out histologic, biochemical, and gene-expression studies on these specimens. RESULTS As compared with diaphragm-biopsy specimens from controls, specimens from case subjects showed decreased cross-sectional areas of slow-twitch and fast-twitch fibers of 57% (P=0.001) and 53% (P=0.01), respectively, decreased glutathione concentration of 23% (P=0.01), increased active caspase-3 expression of 100% (P=0.05), a 200% higher ratio of atrogin-1 messenger RNA (mRNA) transcripts to MBD4 (a housekeeping gene) (P=0.002), and a 590% higher ratio of MuRF-1 mRNA transcripts to MBD4 (P=0.001). CONCLUSIONS The combination of 18 to 69 hours of complete diaphragmatic inactivity and mechanical ventilation results in marked atrophy of human diaphragm myofibers. These findings are consistent with increased diaphragmatic proteolysis during inactivity.

An ultrasensitive method for quantitating circulating tumor DNA with broad patient coverage.

Circulating tumor DNA (ctDNA) is a promising biomarker for noninvasive assessment of cancer burden, but existing ctDNA detection methods have insufficient sensitivity or patient coverage for broad clinical applicability. Here we introduce cancer personalized profiling by deep sequencing (CAPP-Seq), an economical and ultrasensitive method for quantifying ctDNA. We implemented CAPP-Seq for non–small-cell lung cancer (NSCLC) with a design covering multiple classes of somatic alterations that identified mutations in >95% of tumors. We detected ctDNA in 100% of patients with stage II–IV NSCLC and in 50% of patients with stage I, with 96% specificity for mutant allele fractions down to ∼0.02%. Levels of ctDNA were highly correlated with tumor volume and distinguished between residual disease and treatment-related imaging changes, and measurement of ctDNA levels allowed for earlier response assessment than radiographic approaches. Finally, we evaluated biopsy-free tumor screening and genotyping with CAPP-Seq. We envision that CAPP-Seq could be routinely applied clinically to detect and monitor diverse malignancies, thus facilitating personalized cancer therapy.

Myosin gene mutation correlates with anatomical changes in the human lineage

Powerful masticatory muscles are found in most primates, including chimpanzees and gorillas, and were part of a prominent adaptation of Australopithecus and Paranthropus, extinct genera of the family Hominidae. In contrast, masticatory muscles are considerably smaller in both modern and fossil members of Homo. The evolving hominid masticatory apparatus—traceable to a Late Miocene, chimpanzee-like morphology—shifted towards a pattern of gracilization nearly simultaneously with accelerated encephalization in early Homo. Here, we show that the gene encoding the predominant myosin heavy chain (MYH) expressed in these muscles was inactivated by a frameshifting mutation after the lineages leading to humans and chimpanzees diverged. Loss of this protein isoform is associated with marked size reductions in individual muscle fibres and entire masticatory muscles. Using the coding sequence for the myosin rod domains as a molecular clock, we estimate that this mutation appeared approximately 2.4 million years ago, predating the appearance of modern human body size and emigration of Homo from Africa. This represents the first proteomic distinction between humans and chimpanzees that can be correlated with a traceable anatomic imprint in the fossil record.

Integrated digital error suppression for improved detection of circulating tumor DNA

High-throughput sequencing of circulating tumor DNA (ctDNA) promises to facilitate personalized cancer therapy. However, low quantities of cell-free DNA (cfDNA) in the blood and sequencing artifacts currently limit analytical sensitivity. To overcome these limitations, we introduce an approach for integrated digital error suppression (iDES). Our method combines in silico elimination of highly stereotypical background artifacts with a molecular barcoding strategy for the efficient recovery of cfDNA molecules. Individually, these two methods each improve the sensitivity of cancer personalized profiling by deep sequencing (CAPP-Seq) by about threefold, and synergize when combined to yield ∼15-fold improvements. As a result, iDES-enhanced CAPP-Seq facilitates noninvasive variant detection across hundreds of kilobases. Applied to non-small cell lung cancer (NSCLC) patients, our method enabled biopsy-free profiling of EGFR kinase domain mutations with 92% sensitivity and >99.99% specificity at the variant level, and with 90% sensitivity and 96% specificity at the patient level. In addition, our approach allowed monitoring of NSCLC ctDNA down to 4 in 105 cfDNA molecules. We anticipate that iDES will aid the noninvasive genotyping and detection of ctDNA in research and clinical settings.

Comparison of stages I–II thymoma treated by complete resection with or without adjuvant radiation

BACKGROUND Adjuvant radiation after resection of Masaoka stage II thymoma is widely advocated, but the evidence supporting it is controversial. Studies addressing this issue generally report few patients and lump all patients beyond stage I together in the analysis. METHODS We retrospectively compared outcomes of stage I and II thymomas treated by resection alone with thymomas treated by resection plus radiation. Histology was re-reviewed to confirm pathologic staging and resection margin status. RESULTS Between February 1992 and 2002, we performed 167 resections for thymoma. Of these, 70 patients were believed to have tumors in stage IIb or less intraoperatively, and all of these patients underwent complete resection. We reviewed the histopathology of 62 of 70 patients. Thirty thymomas demonstrated less than complete transcapsular microscopic invasion (stage I) and 40 thymomas demonstrated microscopic transcapsular invasion or macroscopic invasion into surrounding fatty tissue (stage II). Forty-seven patients underwent surgery without postoperative mediastinal radiotherapy. Dosages in the 23 radiated patients (3 stage I and 20 stage II) consisted of 45 to 55 Gy. Median follow-up was 70.3 months. Stage II patients who were radiated (n = 20) and those who were not radiated (n = 20) consisted of identical proportions in stages IIa and IIb. Two patients recurred (1 unradiated stage I patient and 1 radiated stage IIb patient). Overall 5-year survival rate was 91%. All who died were free of recurrence at time of death. Log-rank test showed no difference in Kaplan Meier survival curves (p = 0.32) between the radiated and unradiated groups. CONCLUSIONS These data support the contention that margin-negative surgical resection alone is sufficient treatment for both stages I and II thymoma.

Risk of Death From Intercurrent Disease Is Not Excessively Increased by Modern Postoperative Radiotherapy for High-Risk Resected Non–Small-Cell Lung Carcinoma

PURPOSE Some studies report a high risk of death from intercurrent disease (DID) after postoperative radiotherapy (XRT) for non-small-cell lung cancer (NSCLC). This study determines the risk of DID after modern-technique postoperative XRT. PATIENTS AND METHODS A total of 202 patients were treated with surgery and postoperative XRT for NSCLC. Most patients (97%) had pathologic stage II or III disease. Many patients (41%) had positive/close/uncertain resection margins. The median XRT dose was 55 Gy with fraction size of 1.8 to 2 Gy. The risk of DID was calculated actuarially and included patients who died of unknown/uncertain causes. Median follow-up was 24 months for all patients and 62 months for survivors. RESULTS A total of 25 patients (12.5%) died from intercurrent disease, 16 from confirmed noncancer causes and nine from unknown causes. The 4-year actuarial rate of DID was 13.5%. This is minimally increased compared with the expected rate for a matched population (approximately 10% at 4 years). On multivariate analysis, age and radiotherapy dose were borderline significant factors associated with a higher risk of DID (P =.06). The crude risk of DID for patients receiving less than 54 Gy was 2% (4-year actuarial risk 0%) versus 17% for XRT dose > or = 54 Gy. The 4-year actuarial overall survival was 34%; local control was 84%; and freedom from distant metastases was 37%. CONCLUSION Modern postoperative XRT for NSCLC does not excessively increase the risk of intercurrent deaths. Further study of postoperative XRT, particularly when using more sophisticated treatment planning and reasonable total doses, for carefully selected high-risk resected NSCLC is warranted.

Increased proteolysis, myosin depletion, and atrophic AKT-FOXO signaling in human diaphragm disuse

RATIONALE Patients on mechanical ventilation who exhibit diaphragm inactivity for a prolonged time (case subjects) develop decreases in diaphragm force-generating capacity accompanied by diaphragm myofiber atrophy. OBJECTIVES Our objectives were to test the hypotheses that increased proteolysis by the ubiquitin-proteasome pathway, decreases in myosin heavy chain (MyHC) levels, and atrophic AKT-FOXO signaling play major roles in eliciting these pathological changes associated with diaphragm disuse. METHODS Biopsy specimens were obtained from the costal diaphragms of 18 case subjects before harvest (cases) and compared with intraoperative specimens from the diaphragms of 11 patients undergoing surgery for benign lesions or localized lung cancer (control subjects). Case subjects had diaphragm inactivity and underwent mechanical ventilation for 18 to 72 hours, whereas this state in controls was limited to 2 to 4 hours. MEASUREMENTS AND MAIN RESULTS With respect to proteolysis in cytoplasm fractions, case diaphragms exhibited greater levels of ubiquitinated-protein conjugates, increased activity of the 26S proteasome, and decreased levels of MyHCs and α-actin. With respect to atrophic signaling in nuclear fractions, case diaphragms exhibited decreases in phosphorylated AKT, phosphorylated FOXO1, increased binding to consensus DNA sequence for Atrogin-1 and MuRF-1, and increased supershift of DNA-FOXO1 complexes with specific antibodies against FOXO1, as well as increased Atrogin-1 and MuRF-1 transcripts in whole myofiber lysates. CONCLUSIONS Our findings suggest that increased activity of the ubiquitin-proteasome pathway, marked decreases in MyHCs, and atrophic AKT-FOXO signaling play important roles in eliciting the myofiber atrophy and decreases in diaphragm force generation associated with prolonged human diaphragm disuse.

Transcervical Thymectomy for Myasthenia Gravis Achieves Results Comparable to Thymectomy by Sternotomy

BACKGROUND It remains controversial whether transcervical thymectomy offers results equivalent to thymectomy by way of a median sternotomy in the treatment of myasthenia gravis. Furthermore, preoperative prognostic factors have not been clearly defined. METHODS This study is a retrospective chart review and interview of 78 patients completing transcervical thymectomy for myasthenia gravis between 1992 and 1999. RESULTS There were 24 men and 54 women. Mean age was 40 years (range, 13 to 78 years). Twelve patients were in Osserman class 1, 25 in class 2, 30 in class 3, and 11 in class 4 (mean, 2.5). There was no perioperative mortality and 6 (7.7%) morbidities. Mean length of stay was 1.5 days and mean follow-up, 54.6 months. The crude cumulative complete remission (asymptomatic off medications for 6 months) rate was 39.7% (n = 31). Only 8 patients (10.3%) failed to improve after transcervical thymectomy. Kaplan-Meier estimates of complete remission were 31% and 43% at 2 and 5 years, respectively. Eight patients with thymoma had a 5-year estimated complete remission rate of 75% in contrast to 43% in 38 patients with thymic hyperplasia and 36% in 32 patients with neither thymoma nor hyperplasia (p = 0.01). Twelve patients with ocular myasthenia had a 5-year estimated complete remission rate of 57%, whereas patients with mild-to-moderate (n = 55) or severe (n = 11) generalized symptoms had 5-year complete remission rates of 43% and 30%, respectively (p = 0.21). CONCLUSIONS Overall, extended transcervical thymectomy offers results that are comparable to those published for the transsternal procedure. Patients with milder disease (including isolated ocular disease) and taking no preoperative immunosuppressive agents appear to experience higher remission rates. In contrast to previous studies, we also find that small thymomas predict better responses to thymectomy.

A Rare Population of CD24+ITGB4+Notchhi Cells Drives Tumor Propagation in NSCLC and Requires Notch3 for Self-Renewal

Sustained tumor progression has been attributed to a distinct population of tumor-propagating cells (TPCs). To identify TPCs relevant to lung cancer pathogenesis, we investigated functional heterogeneity in tumor cells isolated from Kras-driven mouse models of non-small-cell lung cancer (NSCLC). CD24(+)ITGB4(+)Notch(hi) cells are capable of propagating tumor growth in both a clonogenic and an orthotopic serial transplantation assay. While all four Notch receptors mark TPCs, Notch3 plays a nonredundant role in tumor cell propagation in two mouse models and in human NSCLC. The TPC population is enriched after chemotherapy, and the gene signature of mouse TPCs correlates with poor prognosis in human NSCLC. The role of Notch3 in tumor propagation may provide a therapeutic target for NSCLC.

Bronchopulmonary carcinoid tumors associated with cushing's syndrome: A more aggressive variant of typical carcinoid

OBJECTIVES Our objectives were to delineate the clinicopathologic characteristics of adrenocorticotropin-secreting bronchopulmonary carcinoid tumors causing Cushings syndrome and to derive from these findings a rational approach to diagnosis and surgical management of this unusual condition. METHODS We conducted a retrospective, chart-review analysis of seven consecutive patients treated at the Massachusetts General Hospital over a 16-year period. RESULTS The patients uniformly had symptoms of marked hypercortisolism, and the underlying lung lesions remained clinically occult for a mean of 24 months. Standard endocrine testing was misleading in 83% of patients, reinforcing the need for an alternative diagnostic strategy based on petrosal sinus catheterization and computed tomography of the chest. Although 72% of the tumors were typical carcinoids by standard criteria, 57% demonstrated microscopic evidence of local invasiveness, and 43% were associated with mediastinal lymph node metastases. Eighty-six percent of patients have been cured by pulmonary resection a mean of 59 months after the operation, but 50% of these required a second operation for resection of involved lymph nodes after an initial relapse. CONCLUSIONS These data suggest that adrenocorticotropin-secreting bronchopulmonary carcinoid tumors represent a distinct, more aggressive subtype of the usual, typical carcinoid. The high rate of lymphatic and local spread demands a surgical approach consisting of anatomic resection and routine mediastinal lymph node dissection.