Publisher's Note: Asymptotic self-restabilization of a continuous elastic structure [Phys. Rev. E 94, 063005 (2016)].

This corrects the article DOI: 10.1103/PhysRevE.94.063005.

Asymptotic self-restabilization of a continuous elastic structure.

A challenge in soft robotics and soft actuation is the determination of an elastic system that spontaneously recovers its trivial path during postcritical deformation after a bifurcation. The interest in this behavior is that a displacement component spontaneously cycles around a null value, thus producing a cyclic soft mechanism. An example of such a system is theoretically proven through the solution of the elastica and a stability analysis based on dynamic perturbations. It is shown that the asymptotic self-restabilization is driven by the development of a configurational force, of similar nature to the Peach-Koehler interaction between dislocations in crystals, which is derived from the principle of least action. A proof-of-concept prototype of the discovered elastic system is designed, realized, and tested, showing that this innovative behavior can be obtained in a real mechanical apparatus.

Self-encapsulation, or the 'dripping' of an elastic rod.

A rod covering a fixed span is loaded at the middle with a transverse force, such that with increasing load a progressive deflection occurs. After a certain initial deflection, a phenomenon is observed where two points of the rod come in contact with each other. This is defined as the 'dripping point' and is when 'self-encapsulation' of the elastic rod occurs. Dripping seems at a first glance to be impossible and definitely cannot occur in the presence of 'ordinary' constraints (such as simple supports or clamps) at the ends of the span. However, the elastica governs oscillating pendulums, buckling rods and pendant drops, so that a possibility for self-encapsulation might be imagined. This phenomenon is indeed demonstrated (both theoretically and experimentally) to occur when at least one of the constraints at the ends of the rod is a sliding sleeve. This mechanical device generates a configurational force, causing the dripping of the rod, in a fully elastic set-up.

Torsional locomotion.

One edge of an elastic rod is inserted into a friction-less and fitting socket head, whereas the other edge is subjected to a torque, generating a uniform twisting moment. It is theoretically shown and experimentally proved that, although perfectly smooth, the constraint realizes an expulsive axial force on the elastic rod, which amount is independent of the shape of the socket head. The axial force explains why screwdrivers at high torque have the tendency to disengage from screw heads and demonstrates torsional locomotion along a perfectly smooth channel. This new type of locomotion finds direct evidence in the realization of a 'torsional gun', capable of transforming torque into propulsive force.

An elastica arm scale.

The concept of a 'deformable arm scale' (completely different from a traditional rigid arm balance) is theoretically introduced and experimentally validated. The idea is not intuitive, but is the result of nonlinear equilibrium kinematics of rods inducing configurational forces, so that deflection of the arms becomes necessary for equilibrium, which would be impossible for a rigid system. In particular, the rigid arms of usual scales are replaced by a flexible elastic lamina, free to slide in a frictionless and inclined sliding sleeve, which can reach a unique equilibrium configuration when two vertical dead loads are applied. Prototypes designed to demonstrate the feasibility of the system show a high accuracy in the measurement of load within a certain range of use. Finally, we show that the presented results are strongly related to snaking of confined beams, with implications for locomotion of serpents, plumbing and smart oil drilling.

Structure of the molten salt methyl ammonium nitrate explored by experiments and theory.

We present an analysis of the structure of the monomethylammonium nitrate (MMAN) compound. Vibrational Raman spectroscopy and X-ray powder diffraction have been used to characterize the bulk phases of MMAN, and assignment of the resonant frequencies has been performed by ab initio (DFT) computations on small clusters of the compound. The theoretical spectra are in excellent agreement with the experimental ones and provide a means by which an interpretation of the hydrogen-bonding network that exists in such compound can be analyzed. In particular, we found that the spectrum of one of the solid phases is structurally very similar to that of the liquid. We present experimental evidence for the existence of such phase both from X-ray data and Raman spectra which, in turn, is easily interpreted with a one-to-one correspondence with the ab initio simulation of the small clusters. A geometric structure of the short-range local arrangement in these two bulk phases is therefore proposed.

Isolation of pulmonary interstitial fluid in rabbits by a modified wick technique.

Interstitial fluid protein concentration (C(protein)) values in perivascular and peribronchial lung tissues were never simultaneously measured in mammals; in this study, perivascular and peribronchial interstitial fluids were collected from rabbits under control conditions and rabbits with hydraulic edema or lesional edema. Postmortem dry wicks were implanted in the perivascular and peribronchial tissues; after 20 min, the wicks were withdrawn and the interstitial fluid was collected to measure C(protein) and colloid osmotic pressure. Plasma, perivascular, and peribronchial C(protein) values averaged 6.4 +/- 0.7 (SD), 3.7 +/- 0.5, and 2.4 +/- 0.7 g/dl, respectively, in control rabbits; 4.8 +/- 0.7, 2.5 +/- 0.6, and 2.4 +/- 0.4 g/dl, respectively, in rabbits with hydraulic edema; and 5.1 +/- 0.3, 4.3 +/- 0.4 and 3.3 +/- 0.6 g/dl, respectively, in rabbits with lesional edema. Contamination of plasma proteins from microvascular lesions during wick insertion was 14% of plasma C(protein). In control animals, pulmonary interstitial C(protein) was lower than previous estimates from pre- and postnodal pulmonary lymph; furthermore, although the interstitium constitutes a continuum within the lung parenchyma, regional differences in tissue content seem to exist in the rabbit lung.

Respiratory bronchiolitis-associated interstitial lung disease: a case report with bronchoalveolar lavage findings.

We report a case of respiratory bronchiolitis-associated interstitial lung disease in a young asymptomatic heavy cigarette smoker. Diagnosis was achieved by examination of specimens obtained from open lung biopsy, but retrospective evaluation of bronchoalveolar lavage findings offer some circumstantial suggestions. We provide evidence for the nature of inclusions contained in alveolar macrophages. Problems related to the classification of respiratory bronchiolitis-associated interstitial lung disease are also discussed.

Endocrine tumors of the small and large intestine.

Among endocrine tumors arising in the intestinal tract, midgut argentaffin EC cell carcinoids, duodenal gastrin cell tumors and rectal trabecular L cell carcinoids, in order of decreasing frequency, are those better represented. Together they account for more than 80% of such tumors. Duodenal somatostatin cell tumors, gangliocytic paragangliomas and poorly differentiated neuroendocrine carcinomas, are also well defined tumor entities. The carcinoid syndrome with intermittent flushing, hypotension and diarrhea, and the Zollinger-Ellison syndrome with severe peptic ulcer disease, are the only hyperfunctional syndromes consistently found in association with these tumors. The carcinoid syndrome arises in about 10% of intestinal carcinoids, usually in their advanced metastatic stage. The Zollinger-Ellison syndrome occurs in association with about 40% of gastrin cell tumors, including small intramural growths. Tumor prognosis depends on mode and site of presentation, histology, cell type(s), size, level of invasion, metastases (especially distant metastases) and associated clinical syndrome or background disease.

Radioimmunoassisted follow-up and surgery vs traditional examinations and surgery after radical excision of colorectal cancer.

The authors report their experience in the radioimmunodetection of recurrent colorectal cancer in comparison with traditional examinations. 485 patients were studied after radical surgery for colorectal cancer: 168 (Group 1) were studied with a radioimmunoassisted follow-up plan including: Immunoscintigraphy (IS), serum markers assays, Radioimmunoguided Endoscopy (RIGE), Intraoperative Radioimmuno-localization (IORIL) in case of reoperation; 317 (Group 2) underwent a protocol with traditional examinations. In 24 patients of Group 1 IS was performed even at the time of their admission for primary cancer. 7 patients underwent RIGE for primary cancer and 16 in the follow-up. IORIL was performed in 12 patients with primary cancer and in 16 in the course of reoperation. The radioimmunodiagnostic methods were performed after a single administration of the radiolabeled MAb (111In F(ab')2 a-CEA and 111In B72.3). The radioimmunoassisted follow-up plan detected a greater number of recurrences than traditional examinations (27% vs 13%). The rates of radical reoperation in Group 1 and 2 were 61% and 37% respectively. 33% of the patients of Group 2 were alive 24 months after radical reoperation vs 62.5% of the patients of Group 1. Immunoscintigraphy demonstrated a good sensitivity and specificity, mainly in the detection of pelvic recurrences (sens. 92%, spec. 84%). The radioimmunoassisted follow-up plan was well accepted by the patients. RIGE led to the detection of 3 periluminal recurrences of rectal cancer that traditional investigations failed to demonstrate and in 5 cases influenced the patients management. IORIL detected minimal tumor foci (2 mm.) where pre and intraoperative study were negative, while the histopathologic examination gave evidence of tumor. Considering that the costs of the radioimmunodiagnostic methods and of traditional examinations are very similar, we can conclude that the radioimmunoassisted follow-up plan has a favorable cost/benefit rate and a remarkable impact on the treatment of patients with colorectal cancer.

K-ras gene mutations: an unfavorable prognostic marker in stage I lung adenocarcinoma.

Activation of K-ras gene by point mutations, a common finding in lung adenocarcinomas, has been suggested to decrease patient survival. We investigated 109 lung adenocarcinomas, mostly small, peripheral, stage I tumours (81/109) for presence of K-ras gene mutations at codons 12 and 13. Mutations were detected by denaturing gradient gel electrophoresis analysis of specific sequences amplified by polymerase chain reaction from DNA extracted from archival pathological material. Thirty-three of 109 (30.3%) tumours showed mutations at codon 12 (28/33, 84.8%) or 13 (5/33, 15.2%) of the gene. Mutations and type of nucleotide substitutions were differently distributed among cytological subtypes, being more prevalent among less differentiated (G2 and G3) tumours and among bronchial than bronchiolo-alveolar type adenocarcinomas. Survival analysis showed an adverse effect of K-ras mutation on survival, restricted to stage I tumours. Median survival for 81 stage I patients was 30 months for non-mutated tumours versus 20 months for mutated tumours (p = 0.016). Multivariate analysis showed that age of patient (p = 0.001) and K-ras mutation status (p = 0.04) were the only independent factors influencing survival significantly. These data strengthen the hypothesis that K-ras gene mutations may be useful in identifying a subgroup of patients with poor outcome.

Transbronchial biopsy in lymphangiomyomatosis of the lung. HMB45 for diagnosis.

We have investigated the presence of smooth muscle cells with immunoreactivity for melanoma-related marker HMB45 in pulmonary lymphangiomyomatosis (PLAM). Of 75 lung specimens, including a variety of lesions (obtained with both transbronchial and open lung biopsies), only PLAM (six specimens from three patients) showed the presence of HMB45-positive cells. In addition, 20 specimens of normal lung were unreactive with this monoclonal antibody. It is concluded that the smooth muscle cells of PLAM regularly exhibit a peculiar phenotype, characterized by HMB45 immunoreactivity, distinct from other smooth muscle proliferations; and the histological diagnosis of PLAM can be made when only a transbronchial biopsy is available.

Aspartic proteinases in normal lung and interstitial pulmonary diseases.

Two aspartic proteinases, pepsinogen II (PgII) and cathepsin E (CathE), were identified immunocytochemically in lung epithelia. In normal lung, type II pneumocytes were characterized by PgII immunoreactivity of variable intensity, while bronchiolar Clara cells reacted with CathE antibodies. With the exception of small groups of nonciliated bronchial cells overlying lymphoid follicles, no other CathE-immunoreactive cell was found in the lung. Immunoblots of crude protein extracts of lung tissue using PgII and CathE antibodies showed reactivity with single molecular species co-migrating with analogous bands obtained from gastric mucosa (molecular weight, 40,500 for PgII and 42,000 to 44,000 for CathE). In 75 cases of non-neoplastic lung disease, a highly significant correlation was found between the severity of histopathologic lesions and expression of both PgII (P < 0.001) and CathE (P < 0.001). Epithelial hyperplasia contributed more than inflammation and fibrosis to this relationship. Proteinase overexpression was not specific to any particular disease and was found in both focal and diffuse lesions. Segregation of PgII and CathE in different cells was lost in hyperplastic epithelium, where coexpression of both proteinases by the same cell was frequently observed. The location of both proteinases in distal airways and their enhanced expression in the proliferative, hyperplastic phase of several non-neoplastic pneumopathies suggest their possible involvement in the process of parenchymal remodeling that occurs in fibrosing lung diseases.

Cathepsin E in follicle associated epithelium of intestine and tonsils: localization to M cells and possible role in antigen processing.

A specific rabbit anti-human serum was used selectively to localize the aspartic proteinase cathepsin E to follicle associated epithelium (FAE) of human and rat intestine, including jejunum, ileum, appendix, colon and rectum, as well as of human palatine, pharyngeal and lingual tonsils. Coexpression of class II histocompatibility antigen HLA-DR antigen has been observed in some of the cathepsin E-positive epithelial cells. In addition, cathepsin E has been detected in a few mononuclear cells of intestinal lymphoid structures and tonsils resembling interdigitating reticulum cells of lymph nodes. Another aspartic proteinase, cathepsin D, has been found to be poorly represented in FAE and intensely expressed by macrophages. Electron immunocytochemistry localized cathepsin E to endosomal vesicles and endoplasmic reticulum of M cells in rat and human ileum as well as of M-like cells in human palatine tonsil. The results suggest a possible role of endosomal cathepsin E in the processing of macromolecules and microorganisms transported by M cells and related epithelial cells to mucosal associated lymphoid tissue (MALT).

Cathepsin E in antigen-presenting Langerhans and interdigitating reticulum cells. Its possible role in antigen processing.

A specific rabbit anti-human cathepsin E serum detected this aspartic proteinase in Langerhans cells of the skin, in interdigitating reticulum cells of lymph nodes and spleen and in histiocytosis X cells, but not in macrophages. Immunoblotting of tissue extracts confirmed the presence of cathepsin E in skin and lymph nodes. Electron immunocytochemistry with the protein A gold technique localized cathepsin E in the endoplasmic reticulum and in endosomal vesicles of both interdigitating and Langerhans cells, likely involving Birbeck bodies. A role of endosomal cathepsin E in antigen processing is suggested.

Primary solitary intracranial melanoma: case report and review of the literature.

Among CNS tumors, intracranial melanomas represent a subject of interest for neurooncologists and neurosurgeons because clinical and radiological patterns of these tumors can mimic the presence of meningiomas, and in spite of their malignant behavior they can be satisfactorily treated. In the present report we describe a new case of primary intracranial melanoma that displayed some radiological features of meningioma; we review the clinical features of 80 previously well-documented cases. The importance of neuroradiological and histochemical (S-100 protein, antimelanin antibodies, proliferating cell nuclear antigen staining) methods and of flow cytometry in helping with histopathological examination is stressed. Review of the clinical histories demonstrates that surgical excision is recommended in most cases, depending on tumor location, and that if total removal is performed, long-term disease-free periods can be attained.

[A rare case of massive digestive hemorrhage. Carcinoid of the small intestine]. / Un raro caso di emorragia digestiva massiva. Il carcinoide del piccolo intestino.

The authors reports a case of massive digestive hemorrhage produce by a carcinoid of the small intestine. Having reviewed the most frequent causes of primary hemorrhage of the mesenteric small intestine, attention is focused on the difficulties o making an etiological and topographical diagnosis, in spite of using the most advanced instrumental research methods. The paper concludes that explorative laparotomy is the sole method for making a precise diagnosis and performing appropriate surgical treatment.

Differential diagnostic patterns of lung neuroendocrine tumours. A clinico-pathological and immunohistochemical study of 122 cases.

A series of 3 tumourlets (TLs), 81 typical carcinoids (TCs), 14 atypical carcinoids (ACs) (well-differentiated neuroendocrine carcinomas, WDNCs) and 24 small cell-intermediate cell carcinomas (SCC-ICCs) of the lung were studied. Histopathological features were correlated with amine and peptide hormone immunoreactivity and with clinical data. All types of tumours expressed general neuroendocrine (NE) markers: Grimelius positivity and chromogranins were detected more frequently in well-differentiated (TLs, TCs) than in less well differentiated tumours [ACs (WDNCs) and SCC-ICCs] whereas neuron specific enolase (NSE) was prominent in the latter tumours. TLs and peripheral TCs were benign, often showing a paraganglioid pattern and frequently expressing gastrin-releasing peptide (GRP), which is present in the peripheral airways of normal lung. Central TCs were associated with lymph node metastases in 8.5% of the cases, frequently had a trabecular architecture, often associated with human milk fat globule 2 (HMFG2)-positive acinar and rosette-like structures, and were mainly immunostained for the alpha-subunit of human chorionic gonadotrophin (alpha-hCG) and serotonin. ACs (WDNCs) were associated with intrathoracic and/or extrathoracic metastases in 57.1% of the cases with a mortality rate of 35.7%. Their histological and cytological features were intermediate between those of TCs and SCC-ICCs. ACs (WDNCs) expressed serotonin and alpha-hCG less frequently than TCs. All SCC-ICCs were surgically treated and displayed a mortality rate of 91.6% with a mean survival of 10.2 months after operation. These tumours were characterized by high expression of HMFG2 and NSE, while the expression of both orthotopic (serotonin, GRP) and ectopic (ACTH) specific NE substances was very low. Since all TCs (either central or peripheral) had a favourable outcome, while about 36% of ACs (WDNCs) were fatal, the latter seem more appropriately designated "well-differentiated NE carcinomas". The differential diagnosis between different NE tumours of the lung is important and is mainly based on morphology. Both panendocrine and specific immunohistochemical markers are helpful in distinguishing the less aggressive, mostly benign varieties from the more malignant varieties.

The gastroenteropancreatic endocrine system and related tumors.

Up to 16 types of endocrine cells have been characterized morphologically (and most of them also functionally) in the gastroenteropancreatic area. Four main groups of pancreatic endocrine tumors (with several subtypes) have been identified: islet cell, ectopic, nonfunctioning, and poorly differentiated tumors. A detailed classification system that combines cytologic and clinicopathologic patterns has been developed for the study of 132 pancreatic tumors. Among a large series (more than 120 cases) of endocrine tumors arising in the gastrointestinal tract, serotonin-producing argentaffin carcinoids have been separated from hindgut trabecular carcinoids, producing glucagon- and pancreatic polypeptide-related peptides, paragangliomas, somatostatin cell tumors, gastrinomas, and argyrophil ECL cell carcinoids. The clinicopathologic profile of the various pancreatic and gastrointestinal tumor entities has been delineated and involvement in the multiple endocrine neoplasia syndrome has been analyzed in detail.