How Tim proteins differentially exploit membrane features to attain robust target sensitivity

Immune surveillance cells such as T cells and phagocytes utilize integral plasma membrane receptors to recognize surface signatures on triggered and activated cells such as those in apoptosis. One such family of plasma membrane sensors, the transmembrane immunoglobulin and mucin domain (Tim) proteins, specifically recognize phosphatidylserine (PS) but elicit distinct immunological responses. The molecular basis for the recognition of lipid signals on target cell surfaces is not well understood. Previous results suggest that basic side chains present at the membrane interface on the Tim proteins might facilitate association with additional anionic lipids including but not necessarily limited to PS. We, therefore, performed a comparative quantitative analysis of the binding of the murine Tim1, Tim3, and Tim4, to synthetic anionic phospholipid membranes under physiologically relevant conditions. X-ray reflectivity and vesicle binding studies were used to compare the water-soluble domain of Tim3 with results previously obtained for Tim1 and Tim4. Although a calcium link was essential for all three proteins, the three homologs differed in how they balance the hydrophobic and electrostatic interactions driving membrane association. The proteins also varied in their sensing of phospholipid chain unsaturation and showed different degrees of cooperativity in their dependence on bilayer PS concentration. Surprisingly, trace amounts of anionic phosphatidic acid greatly strengthened the bilayer association of Tim3 and Tim4, but not Tim1. A novel mathematical model provided values for the binding parameters and illuminated the complex interplay among ligands. In conclusion, our results provide a quantitative description of the contrasting selectivity used by three Tim proteins in the recognition of phospholipids presented on target cell surfaces. This paradigm is generally applicable to the analysis of the binding of peripheral proteins to target membranes through the heterotropic cooperative interactions of multiple ligands.

Inhibition of CDK4/6 Promotes CD8 T-cell Memory Formation

CDK4/6 inhibitors are approved to treat breast cancer and are in trials for other malignancies. We examined CDK4/6 inhibition in mouse and human CD8+ T cells during early stages of activation. Mice receiving tumor-specific CD8+ T cells treated with CDK4/6 inhibitors displayed increased T-cell persistence and immunologic memory. CDK4/6 inhibition upregulated MXD4, a negative regulator of MYC, in both mouse and human CD8+ T cells. Silencing of Mxd4 or Myc in mouse CD8+ T cells demonstrated the importance of this axis for memory formation. We used single-cell transcriptional profiling and T-cell receptor clonotype tracking to evaluate recently activated human CD8+ T cells in patients with breast cancer before and during treatment with either palbociclib or abemaciclib. CDK4/6 inhibitor therapy in humans increases the frequency of CD8+ memory precursors and downregulates their expression of MYC target genes, suggesting that CDK4/6 inhibitors in patients with cancer may augment long-term protective immunity. SIGNIFICANCE: CDK4/6 inhibition skews newly activated CD8+ T cells toward a memory phenotype in mice and humans with breast cancer. CDK4/6 inhibitors may have broad utility outside breast cancer, particularly in the neoadjuvant setting to augment CD8+ T-cell priming to tumor antigens prior to dosing with checkpoint blockade.This article is highlighted in the In This Issue feature, p. 2355.

Neoadjuvant Nivolumab or Nivolumab Plus Ipilimumab in Untreated Oral Cavity Squamous Cell Carcinoma: A Phase 2 Open-Label Randomized Clinical Trial

Importance

Novel approaches are needed to improve outcomes in patients with squamous cell carcinoma of the oral cavity. Neoadjuvant immunotherapy given prior to surgery and combining programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) immune checkpoint inhibitors are 2 strategies to enhance antitumor immune responses that could be of benefit.

Design, Setting, and Participants

In this randomized phase 2 clinical trial conducted at 1 academic center, 29 patients with untreated squamous cell carcinoma of the oral cavity (≥T2, or clinically node positive) were enrolled between 2016 to 2019.

Interventions

Treatment was administered with nivolumab, 3 mg/kg, weeks 1 and 3, or nivolumab and ipilimumab (ipilimumab, 1 mg/kg, given week 1 only). Patients had surgery 3 to 7 days following cycle 2.

Main Outcomes and Measures

Safety and volumetric response determined using bidirectional measurements. Secondary end points included pathologic and objective response, progression-free survival (PFS), and overall survival. Multiplex immunofluorescence was used to evaluate primary tumor immune markers.

Results

Fourteen patients were randomized to nivolumab (N) and 15 patients to nivolumab/ipilimumab (N+I) (mean [SD] age, 62 [12] years; 18 men [62%] and 11 women [38%]). The most common subsite was oral tongue (n = 16). Baseline clinical staging included patients with T2 (n = 20) or greater (n = 9) T stage and 17 patients (59%) with node-positive disease. Median time from cycle 1 to surgery was 19 days (range, 7-21 days); there were no surgical delays. There were toxic effects at least possibly related to study treatment in 21 patients, including grade 3 to 4 events in 2 (N), and 5 (N+I) patients. One patient died of conditions thought unrelated to study treatment (postoperative flap failure, stroke). There was evidence of response in both the N and N+I arms (volumetric response 50%, 53%; pathologic downstaging 53%, 69%; RECIST response 13%, 38%; and pathologic response 54%, 73%, respectively). Four patients had major/complete pathologic response greater than 90% (N, n = 1; N+I, n = 3). With 14.2 months median follow-up, 1-year progression-free survival was 85% and overall survival was 89%.

Conclusions and Relevance

Treatment with N and N+I was feasible prior to surgical resection. We observed promising rates of response in both arms, supporting further neoadjuvant studies with these agents.

Trial Registration

ClinicalTrials.gov Identifier: NCT02919683.

Immunosuppressive Myeloid Cells Induce Nitric Oxide-Dependent DNA Damage and p53 Pathway Activation in CD8+ T Cells

Tumor-infiltrating myeloid-derived suppressor cells (MDSC) are associated with poor survival outcomes in many human cancers. MDSCs inhibit T cell-mediated tumor immunity in part because they strongly inhibit T-cell function. However, whether MDSCs inhibit early or later steps of T-cell activation is not well established. Here we show that MDSCs inhibited proliferation and induced apoptosis of CD8⁺ T cells even in the presence of dendritic cells (DC) presenting a high-affinity cognate peptide. This inhibitory effect was also observed with delayed addition of MDSCs to cocultures, consistent with functional data showing that T cells expressed multiple early activation markers even in the presence of MDSCs. Single-cell RNA-sequencing analysis of CD8⁺ T cells demonstrated a p53 transcriptional signature in CD8⁺ T cells cocultured with MDSCs and DCs. Confocal microscopy showed induction of DNA damage and nuclear accumulation of activated p53 protein in a substantial fraction of these T cells. DNA damage in T cells was dependent on the iNOS enzyme and subsequent nitric oxide release by MDSCs. Small molecule-mediated inhibition of iNOS or inactivation of the Nos2 gene in MDSCs markedly diminished DNA damage in CD8⁺ T cells. DNA damage in CD8⁺ T cells was also observed in KPC pancreatic tumors but was reduced in tumors implanted into Nos2-deficient mice compared with wild-type mice. These data demonstrate that MDSCs do not block early steps of T-cell activation but rather induce DNA damage and p53 pathway activation in CD8⁺ T cells through an iNOS-dependent pathway.

Synthetic Lethal and Resistance Interactions with BET Bromodomain Inhibitors in Triple-Negative Breast Cancer

BET bromodomain inhibitors (BBDIs) are candidate therapeutic agents for triple-negative breast cancer (TNBC) and other cancer types, but inherent and acquired resistance to BBDIs limits their potential clinical use. Using CRISPR and small-molecule inhibitor screens combined with comprehensive molecular profiling of BBDI response and resistance, we identified synthetic lethal interactions with BBDIs and genes that, when deleted, confer resistance. We observed synergy with regulators of cell cycle progression, YAP, AXL, and SRC signaling, and chemotherapeutic agents. We also uncovered functional similarities and differences among BRD2, BRD4, and BRD7. Although deletion of BRD2 enhances sensitivity to BBDIs, BRD7 loss leads to gain of TEAD-YAP chromatin binding and luminal features associated with BBDI resistance. Single-cell RNA-seq, ATAC-seq, and cellular barcoding analysis of BBDI responses in sensitive and resistant cell lines highlight significant heterogeneity among samples and demonstrate that BBDI resistance can be pre-existing or acquired.

Acquired resistance to combined BET and CDK4/6 inhibition in triple-negative breast cancer

BET inhibitors are promising therapeutic agents for the treatment of triple-negative breast cancer (TNBC), but the rapid emergence of resistance necessitates investigation of combination therapies and their effects on tumor evolution. Here, we show that palbociclib, a CDK4/6 inhibitor, and paclitaxel, a microtubule inhibitor, synergize with the BET inhibitor JQ1 in TNBC lines. High-complexity DNA barcoding and mathematical modeling indicate a high rate of de novo acquired resistance to these drugs relative to pre-existing resistance. We demonstrate that the combination of JQ1 and palbociclib induces cell division errors, which can increase the chance of developing aneuploidy. Characterizing acquired resistance to combination treatment at a single cell level shows heterogeneous mechanisms including activation of G1-S and senescence pathways. Our results establish a rationale for further investigation of combined BET and CDK4/6 inhibition in TNBC and suggest novel mechanisms of action for these drugs and new vulnerabilities in cells after emergence of resistance.

Inhibition of Haspin Kinase Promotes Cell-Intrinsic and Extrinsic Antitumor Activity

Patients with melanoma resistant to RAF/MEK inhibitors (RMi) are frequently resistant to other therapies, such as immune checkpoint inhibitors (ICI), and individuals succumb to their disease. New drugs that control tumor growth and favorably modulate the immune environment are therefore needed. We report that the small-molecule CX-6258 has potent activity against both RMi-sensitive (RMS) and -resistant (RMR) melanoma cell lines. Haspin kinase (HASPIN) was identified as a target of CX-6258. HASPIN inhibition resulted in reduced proliferation, frequent formation of micronuclei, recruitment of cGAS, and activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway. In murine models, CX-6258 induced a potent cGAS-dependent type-I IFN response in tumor cells, increased IFNγ-producing CD8+ T cells, and reduced Treg frequency in vivo. HASPIN was more strongly expressed in malignant compared with healthy tissue and its inhibition by CX-6258 had minimal toxicity in ex vivo-expanded human tumor-infiltrating lymphocytes (TIL), proliferating TILs, and in vitro differentiated neurons, suggesting a potential therapeutic index for anticancer therapy. Furthermore, the activity of CX-6258 was validated in several Ewing sarcoma and multiple myeloma cell lines. Thus, HASPIN inhibition may overcome drug resistance in melanoma, modulate the immune environment, and target a vulnerability in different cancer lineages. SIGNIFICANCE: HASPIN inhibition by CX-6258 is a novel and potent strategy for RAF/MEK inhibitor-resistant melanoma and potentially other tumor types. HASPIN inhibition has direct antitumor activity and induces a favorable immune microenvironment.

Discovery of specialized NK cell populations infiltrating human melanoma metastases

NK cells contribute to protective antitumor immunity, but little is known about the functional states of NK cells in human solid tumors. To address this issue, we performed single-cell RNA-seq analysis of NK cells isolated from human melanoma metastases, including lesions from patients who had progressed following checkpoint blockade. This analysis identified major differences in the transcriptional programs of tumor-infiltrating compared with circulating NK cells. Tumor-infiltrating NK cells represented 7 clusters with distinct gene expression programs indicative of significant functional specialization, including cytotoxicity and chemokine synthesis programs. In particular, NK cells from 3 clusters expressed high levels of XCL1 and XCL2, which encode 2 chemokines known to recruit XCR1+ cross-presenting DCs into tumors. In contrast, NK cells from 2 other clusters showed a higher level of expression of cytotoxicity genes. These data reveal key features of NK cells in human tumors and identify NK cell populations with specialized gene expression programs.

Subclonal cooperation drives metastasis by modulating local and systemic immune microenvironments

Most human tumours are heterogeneous, composed of cellular clones with different properties present at variable frequencies. Highly heterogeneous tumours have poor clinical outcomes, yet the underlying mechanism remains poorly understood. Here, we show that minor subclones of breast cancer cells expressing IL11 and FIGF (VEGFD) cooperate to promote metastatic progression and generate polyclonal metastases composed of driver and neutral subclones. Expression profiling of the epithelial and stromal compartments of monoclonal and polyclonal primary and metastatic lesions revealed that this cooperation is indirect, mediated through the local and systemic microenvironments. We identified neutrophils as a leukocyte population stimulated by the IL11-expressing minor subclone and showed that the depletion of neutrophils prevents metastatic outgrowth. Single-cell RNA-seq of CD45+ cell populations from primary tumours, blood and lungs demonstrated that IL11 acts on bone-marrow-derived mesenchymal stromal cells, which induce pro-tumorigenic and pro-metastatic neutrophils. Our results indicate key roles for non-cell-autonomous drivers and minor subclones in metastasis.

Effect of synbiotic supplementation on layer production and cecal Salmonella load during a Salmonella challenge

This study analyzed the inhibitory effects of a synbiotic product (PoultryStar® me) on production parameters, intestinal microflora profile, and immune parameters in laying hens with and without a Salmonella challenge. The synbiotic product contained 4 probiotic bacterial strains (Lactobacillus reuteri, Enterococcus faecium, Bifidobacterium animalis, and Pediococcus acidilactici) and a prebiotic fructooligosaccharide. Layers were supplemented with the synbiotic from d of hatch to 28 wk of age. At 16 wk of age, birds were either vaccinated with Salmonella enterica Enteritidis (SE) vaccine or left unvaccinated. At 24 wk of age, a portion of the birds was challenged with 1 × 109 CFU of SE or left unchallenged, resulting in a 3 (vaccinated, challenged, or both vaccinated and challenged) X 2 (control and synbiotics) factorial arrangement of treatments. At 18 and 20 wk of age, birds fed synbiotics in both vaccinated and unvaccinated groups had increased (P < 0.05) BW more than those in the un-supplemented groups. Birds fed synbiotics had 0.7, 17.8, 21.7, 3, and 4.2% higher (P < 0.05) hen d egg production (HDEP) at 19, 20, 21, 22, and 23 wk of age, compared to the birds without supplementation, respectively. After administering the SE challenge, supplemented birds had 3, 6.7, 4.3, 12.5, and 14.4% higher (P < 0.05) HDEP at 24, 25, 26, 27, and 28 wk of age, compared to the birds not supplemented, respectively. Irrespective of the vaccination status, birds fed synbiotics and challenged with SE had a lower (P < 0.05) SE cecal load compared to the un-supplemented groups. At 22 d post Salmonella challenge, birds supplemented, vaccinated, and challenged had the highest bile IgA content. It can be concluded that supplementation of the synbiotic product could be beneficial to layer diets as a growth promoter, performance enhancer, and for protection against SE infection.

Corrigendum: An immunogenic personal neoantigen vaccine for patients with melanoma

This corrects the article DOI: 10.1038/nature22991.

Myelin abnormalities in the optic and sciatic nerves in mice with GM1-gangliosidosis

GM1-gangliosidosis is a glycosphingolipid lysosomal storage disease involving accumulation of GM1 and its asialo form (GA1) primarily in the brain. Thin-layer chromatography and X-ray diffraction were used to analyze the lipid content/composition and the myelin structure of the optic and sciatic nerves from 7- and 10-month old β-galactosidase (β-gal) +/? and β-gal −/− mice, a model of GM1gangliosidosis. Optic nerve weight was lower in the β-gal −/− mice than in unaffected β-gal +/? mice, but no difference was seen in sciatic nerve weight. The levels of GM1 and GA1 were significantly increased in both the optic nerve and sciatic nerve of the β-gal −/− mice. The content of myelin-enriched cerebrosides, sulfatides, and plasmalogen ethanolamines was significantly lower in optic nerve of β-gal −/− mice than in β-gal +/? mice; however, cholesteryl esters were enriched in the β-gal −/− mice. No major abnormalities in these lipids were detected in the sciatic nerve of the β-gal −/− mice. The abnormalities in GM1 and myelin lipids in optic nerve of β-gal −/− mice correlated with a reduction in the relative amount of myelin and periodicity in fresh nerve. By contrast, the relative amount of myelin and periodicity in the sciatic nerves from control and β-gal −/− mice were indistinguishable, suggesting minimal pathological involvement in sciatic nerve. Our results indicate that the greater neurochemical pathology observed in the optic nerve than in the sciatic nerve of β-gal −/− mice is likely due to the greater glycolipid storage in optic nerve.

Peripheral nervous system plasmalogens regulate Schwann cell differentiation and myelination

Rhizomelic chondrodysplasia punctata (RCDP) is a developmental disorder characterized by hypotonia, cataracts, abnormal ossification, impaired motor development, and intellectual disability. The underlying etiology of RCDP is a deficiency in the biosynthesis of ether phospholipids, of which plasmalogens are the most abundant form in nervous tissue and myelin; however, the role of plasmalogens in the peripheral nervous system is poorly defined. Here, we used mouse models of RCDP and analyzed the consequence of plasmalogen deficiency in peripheral nerves. We determined that plasmalogens are crucial for Schwann cell development and differentiation and that plasmalogen defects impaired radial sorting, myelination, and myelin structure. Plasmalogen insufficiency resulted in defective protein kinase B (AKT) phosphorylation and subsequent signaling, causing overt activation of glycogen synthase kinase 3β (GSK3β) in nerves of mutant mice. Treatment with GSK3β inhibitors, lithium, or 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8) restored Schwann cell defects, effectively bypassing plasmalogen deficiency. Our results demonstrate the requirement of plasmalogens for the correct and timely differentiation of Schwann cells and for the process of myelination. In addition, these studies identify a mechanism by which the lack of a membrane phospholipid causes neuropathology, implicating plasmalogens as regulators of membrane and cell signaling.

The majority of CD1d-sulfatide-specific T cells in human blood use a semiinvariant Vδ1 TCR

αβ T-cell lines specific for sulfatide, an abundant myelin glycosphingolipid presented by various CD1 molecules, have been previously derived from PBMCs of patients with demyelinating diseases such as multiple sclerosis (MS) but also from healthy subjects. Using an unbiased tetramer-based MACS enrichment method to enrich for rare antigen-specific cells, we confirmed the presence of CD1d-sulfatide-specific T cells in all healthy individuals examined. Surprisingly, the great majority of fresh sulfatide-specific T cells belonged to the γδ lineage. Furthermore, these cells used the Vδ1 TCR variable segment, which is uncommon in the blood but predominates in tissues such as the gut and specifically accumulates in MS lesions. Recombinant Vδ1 TCRs from different individuals were shown to bind recombinant CD1d-sulfatide complexes in a sulfatide-specific manner. These results provide the first direct demonstration of MHC-like-restricted, antigen-specific recognition by γδ TCRs. Together with previous reports, they support the notion that human Vδ1 T cells are enriched in CD1-specific T cells and suggest that the Vδ1 T-cell population that accumulates in MS lesions might be enriched in CD1-sulfatide-specific cells.

Rapid assessment of internodal myelin integrity in central nervous system tissue

Monitoring pathology/regeneration in experimental models of de-/remyelination requires an accurate measure not only of functional changes but also of the amount of myelin. We tested whether X-ray diffraction (XRD), which measures periodicity in unfixed myelin, can assess the structural integrity of myelin in fixed tissue. From laboratories involved in spinal cord injury research and in studying the aging primate brain, we solicited "blind" samples and used an electronic detector to record rapidly the diffraction patterns (30 min each pattern) from them. We assessed myelin integrity by measuring its periodicity and relative amount. Fixation of tissue itself introduced +/-10% variation in periodicity and +/-40% variation in relative amount of myelin. For samples having the most native-like periods, the relative amounts of myelin detected allowed distinctions to be made between normal and demyelinating segments, between motor and sensory tracts within the spinal cord, and between aged and young primate CNS. Different periodicities also allowed distinctions to be made between samples from spinal cord and nerve roots and between well-fixed and poorly fixed samples. Our findings suggest that, in addition to evaluating the effectiveness of different fixatives, XRD could also be used as a robust and rapid technique for quantitating the relative amount of myelin among spinal cords and other CNS tissue samples from experimental models of de- and remyelination.

Anterior and middle mediastinum paraganglioma: complete resection is the treatment of choice

Paraganglioma of the mediastinum is described to be an indolent and slow-growing tumor. After a patient presented to our center, we reviewed the world literature to evaluate the prognosis of this tumor. This review showed that paragangliomas are locally invasive and have a high local recurrence rate (44/79 or 55.7%) with a true metastatic capacity (21/79 or 26.6%). The overall survival is 62.0% (49/79), but only 36.7% (29/79) of patients could be considered as free of disease, with survival time of 98.2 +/- 11.7 months (mean +/- standard error). The survival with a complete resection is 84.6% (125.7 +/- 18.7 months) versus 50.0% (71.5 +/- 13.8 months) for patients with a biopsy or a partial excision and adjuvant treatment (p < 0.01). We acknowledge the limitation of this retrospective study, but a prospective trial is not possible because of the rarity of the tumor. We want to emphasize that paraganglioma of the anterior and middle mediastinum is an aggressive tumor, and complete surgical resection, using cardiopulmonary bypass if necessary, is highly recommended.

Thoracic outlet syndrome. Thoracic surgery perspective

We have attempted throughout this review to identify the issues surrounding thoracic outlet syndrome as well as to highlight their origins. It should be clear that many aspects of TOS remain controversial from the definition of the entity through pathogenesis, diagnosis, and treatment. The conflicts surrounding TOS are underlined most poignantly in the many letters to the editor of the New England Journal of Medicine in response to Urschel's 1972 publication. It is incumbent upon those of us who treat patients with TOS to dispel the ignorance surrounding this syndrome with astute, accurate, and reproducible observations. We must clearly define TOS as a clinical entity such that we may analyze the characteristics of the patients we treat. We must continue to search for innovative and specific diagnostic criteria. We must quantitatively and reproducibly measure subjective end points of pain severity and quality of life. The use of these methods will provide yardsticks for therapeutic success and act as determinants for the natural history of TOS. The objectives of treatment will remain the alleviation of symptoms and the restoration of function. We have applied these principles to the formulation of a protocol in which we record, in a prospective manner, both routine and innovative clinical parameters. With quantification of subjective end points, we may be able to correlate clinical presentation with outcome. We also may be able to define with some accuracy this entity we call thoracic outlet syndrome.

Pathologic findings in total esophagectomy specimens after intracavitary and external-beam radiotherapy

Pathologic findings in 21 esophagectomy specimens from patients having preoperative combined intracavitary radiotherapy (ICR) and external-beam radiotherapy (EBR) are described. Eleven patients received 1500 cGY ICR and 4000 cGy EBR (Group 1) and ten patients received 1500 cGy plus 2000 to 3000 cGy EBR (Group 2). Effectiveness of radiotherapy was expressed as the ratio between depth of radiation effect and depth of tumor invasion. Depth was expressed as one of four levels: Level I, not deeper than the muscularis mucosa; Level 2, involving but not deeper than submucosa; Level 3, involving but not deeper than muscularis propria; and Level 4, involving periesophageal soft tissue. The depth of radiation damage to tumor cells was comparable between the two groups. However, residual tumor was present in the periesophageal tissue in only one of 11 patients after high-dose EBR compared to of ten patients with lower dose EBR (P less than 0.01, chi-square test). A ratio of one between radiation effect and depth of tumor invasion was present in six patients receiving high-dose EBR and one patient receiving lower dose EBR (P less than 0.05). The authors conclude that ICR combined with EBR affords good local tumor control in the majority of patients. Higher doses of EBR give a better radiation effect in deeper layers of the esophageal wall. The ratio between depth of radiation effect and tumor invasion provides a simple and objective approach to the pathologic analysis of esophagectomy specimens.

Cecal diverticulitis

Cecal diverticulitis is an uncommon entity. Its operative treatment represents 0.2% of procedures performed for an acute abdomen. The clinical presentation is often indistinguishable from acute appendicitis. At operation, it may be confused with cecal carcinoma. The surgeon must be aware of this condition and be prepared to choose the most appropriate treatment. Local excision has been advocated as the treatment of choice. The authors review 18 cases seen over a 10-year period. In no case was the correct diagnosis made preoperatively. Intraoperatively, a correct diagnosis was made in 12 of the 18. Carcinoma was the next most frequent intraoperative diagnosis (four cases). Twelve of the 18 patients were treated by standard or limited right hemicolectomy. One patient died early in the series of sepsis caused by a perforated diverticulum and one patient had a life-threatening complication. Right hemicolectomy appears to be a safe and effective treatment option for cecal diverticulitis.

Lymph node metastases from well-differentiated thyroid cancer. A clinical review

The records of 77 patients with well-differentiated thyroid cancer and proved lymph node metastases have been reviewed. The control of regional metastases was satisfactory in those with only a few nodes involved when limited dissections were utilized initially. In those patients with more extensive nodal involvement, the ultimate rate of failure to control disease in the neck was unacceptably high among those who initially underwent conservative localized neck dissection. Although regional control will not influence mortality, a more aggressive modified neck dissection is recommended for patients presenting with significant nodal involvement.

Morphological and biochemical changes in striated muscle after experimental tourniquet ischaemia

Histological and biochemical changes were studied in the striated muscle following total tourniquet ischaemia between one and four h, the reflow time being 30 min and 24 h. Electronmicroscopy was applied to study the fine structure of the muscle after 24 h reflow. In light microscopy ischaemic changes were not seen even when the tourniquet time was extended to four h. When a four-h ischaemia was followed by a 24-h recovery period, the electron microscopy showed a variety of minor mitochondrial changes such as condensed and slightly dilatated mitochondria. The SDH activities did not vary significantly between the experimental and control samples even after a four-h ischaemia followed by 30 min or 24h reflow. The differences between the experimental and control samples were, however, highly significant in the LDH values in the groups where ischaemia had lasted for three and four h. The results indicate that tourniquet ischaemia for two to three h does not significantly affect the striated muscle of a rabbit and the alterations even after a four-h ischaemia seem to be partly reversible.

Ultrastructural changes in striated muscle after experimental tourniquet ischaemia and short reflow

The effect of experimental tourniquet ischaemia on the fine structure of a rabbit's hind limb striated muscle was studied. The tourniquet time varied from 1 to 4 h. Samples were obtained from the tibialis anterior muscle 30 min after releasing the tourniquet, the contralateral limb serving as the control. As the first sign of ischaemia, dilatation of the sarcoplasmic reticulum was observed after a tourniquet blockade of 1 h. After 4 h ischaemia myofibrillar components showed advanced degeneration. Ultrastructural alterations were distinct in the mitochondrial morphology. After 2 h, the mitochondria showed moderate but clear condensation. After 3 h many mitochondria showed high amplitude swelling and structural disorganization. Total blockade of the limb circulation up to 4 h effects the energy-producing organelles in the first place, especially sarcoplasmic reticulum, T tubules and mitochondria prior to the alterations in myofilaments. Ischaemia extended up to 3 h induces sublethal damage to the muscle cells.