METHODS: A 41-year-old man removed a tungsten carbide ring from his left index finger by cutting it off with a high-speed metal burr. The patient presented two days later with a pink and perfused left index finger with circumferential dry gangrene along the area of the ring, active flexor and extensor tendon excursion, and decreased sensation distally. Within 24 hours, the wound developed into wet gangrene and diffuse cyanosis requiring amputation.
CONCLUSIONS: After reviewing previously documented methods to remove tungsten carbide rings, the authors conclude clinicians should be cognizant of the potential complications associated with the use of a high-speed metal burr.

Employing perylene diimide supermolecule (PDI) as metal-free cocatalyst, a novel PDI/g-C3N4/Bi2WO6 (PCB) photocatalyst was constructed for the effective degradation of antibiotics. Both the photocatalytic activity and photostability of g-C3N4/Bi2WO6 (gCB) were further improved after loading PDI. Under simulated sunlight illumination, the apparent rate constant of tetracycline (TC) degradation by PCB reached 2.6 times that of gCB. The photocatalytic activity of PCB still kept over 80% after 4 cycle experiments, while gCB only remained around 21%. The superior activity of PCB was ascribed to the synergism between the extended visible light absorption range through the participation of PDI cocatalyst and facilitated gCB-to-PDI photoelectron transfer. TC would finally be transformed into non-toxic ring opening products and mineralized. This work demonstrated that PDI was an excellent metal-free cocatalyst and exhibited great potential to boost the activity of photocatalysts.

EXAFS and XANES experiments were used to assess decavanadate interplay with actin, in both the globular and polymerized forms, under different conditions of pH, temperature, ionic strength, and presence of ATP. This approach allowed us to simultaneously probe, for the first time, all vanadium species present in the system. It was established that decavanadate interacts with G-actin, triggering a protein conformational reorientation that induces oxidation of the cysteine core residues and oxidovanadium (VIV) formation. The local environment of vanadium\'s absorbing center in the [decavanadate-protein] adducts was determined, a V-SCys coordination having been verified experimentally. The variations induced in decavanadate\'s EXAFS profile by the presence of actin were found to be almost totally reversed by the addition of ATP, which constitutes a solid proof of decavanadate interaction with the protein at its ATP binding site. Additionally, a weak decavanadate interplay with F-actin was suggested to take place, through a mechanism different from that inferred for globular actin. These findings have important consequences for the understanding, at a molecular level, of the significant biological activities of decavanadate and similar polyoxometalates, aiming at potential pharmacological applications.

Exposure to hard metal (tungsten carbide) dust is a rare cause of interstitial lung disease. Although most cases have a distinctive morphology known as giant cell interstitial pneumonitis, other patterns have been described as well. In such cases, the true nature of the interstitial process may be difficult to recognize. We present a case with unusual morphological features in which analytical scanning electron microscopy (SEM) was used to detect the presence of tungsten as well as other metallic particles. A combination of careful exposure history and examination by analytical SEM is useful for arriving at the correct diagnosis in such difficult cases.

Theoretical consideration and computational simulation have been performed on the voltammetric properties of Keggin polyoxometalates (POMs), and the conversion from successive one-electron transfer in unacidified media to four-electron transfer (through two-electron transfer) in acidified media has been discussed. Perfect simulation of the cyclic voltammograms of POMs could be achieved using the standard formal potentials and the protonation constants, systematically evaluated by the equations, in which “simple (intrinsic)” and “synergistic (extrinsic)” electron-withdrawing effects of the μ4-oxygen were taken into consideration. In the proposed model, the formal potential of the one-electron redox waves for the ith reduction step is presented by Ei°(z0, s) = Ei** + 0.51(z0 – i + 1) + 1.067s (i = 1, 2, 3, 4; E1** = E2** = 0.577 V; E3** = E4** = 0.377 V), where z0 is the initial ionic charge of a Keggin POM and s is the mean bond valence of the μ4-O–W bonds in the POM. The values of Ei**s are related to the energy levels of the two lowest unoccupied molecular orbitals (LUMOs) of a hypothetical Keggin POM with null charge and null bond valence. Then it was revealed that the LUMOs have small on-site repulsion, which may be an important factor that makes multielectron transfer feasible. These findings would give a big clue in developing novel redox materials exhibiting multielectron transfers.

OBJECTIVE: To describe a method of carrying out apical surgery of a maxillary molar using ultrasonics to create a lateral sinus window into the maxillary sinus and an endoscope to enhance visibility during surgery.
CONCLUSIONS: A 37-year-old female patient presented with tenderness to percussion of the maxillary second right molar. Root canal treatment had been undertaken, and the tooth restored with a metal-ceramic crown. Radiological examination revealed an apical radiolucency in close proximity to the maxillary sinus. Apical surgery of the molar was performed through the maxillary sinus, using ultrasonics for the osteotomy, creating a window in the lateral wall of the maxillary sinus. During surgery, the lining of the sinus was exposed and elevated without perforation. The root-end was resected using a round tungsten carbide drill, and the root-end cavity was prepared with ultrasonic retrotips. Root-end filling was accomplished with MTA(®) . An endoscope was used to examine the cut root face, the prepared cavity and the root-end filling. No intraoperative or postoperative complications were observed. At the 12-month follow-up, the tooth had no clinical signs or symptoms, and the radiograph demonstrated progressing resolution of the radiolucency.
CONCLUSIONS: When conventional root canal retreatment cannot be performed or has failed, apical surgery may be considered, even in maxillary molars with roots in close proximity to the maxillary sinus. Ultrasonic sinus window preparation allows more control and can minimize perforation of the sinus membrane when compared with conventional rotary drilling techniques. The endoscope enhances visibility during endodontic surgery, thus improving the quality of the case.

A 36-year-old man, a worker exposed to tungsten and cobalt compounds, was admitted because of chest bilateral micronodular shadow with chronic cough and sputum. Chronic sinusitis, mild hypoxemia, obstructive respiratory impairment and chest radiological findings fulfilled the Japanese diagnostic criteria for diffuse panbronchiolitis, while atypical bronchoalveolar lavage fluid and pathological findings were seen. The surgical lung biopsy specimens showed patchy centrilobular inflammatory change with monocytic infiltrations and particulate deposition inside the area of bronchiolitis, but neither tungsten nor cobalt was found. Treatment with a macrolide antibiotic had no effect on the patient\'s symptoms, hypoxemia and lung function, suggesting bronchiolitis associated with inhalation of hard metal.

BACKGROUND: We report the first case of hard metal lung disease in Singapore and the occupational investigative work and control measures that were undertaken.
METHODS: A 38-year-old machinist in the tool manufacturing industry presented with exertional dyspnoea and cough. Chest X-ray revealed bilateral reticulonodular infiltrates with honeycombing. High resolution computed tomography scan of the thorax confirmed the presence of interstitial fibrosis. Open biopsy of the lung showed features of pneumoconiosis. Particle induced X-ray emission (PIXE) analysis, a relatively new elemental analysis technique, performed on the lung biopsy specimen confirmed the presence of tungsten and titanium; and he was diagnosed to have hard metal lung disease. Microbiologic, serologic and histologic investigations excluded an infective cause. Serial pulmonary function tests on follow-up showed no progression. He presented with haemoptysis 10 months later and was diagnosed to have tuberculosis on the basis of positive sputum and bronchoalveolar lavage cultures for Mycobacterium tuberculosis complex.
METHODS: Preventive measures and permanent transfer to non-cobalt work were instituted.
RESULTS: The interstitial fibrosis appears to have stabilised.
CONCLUSIONS: The diagnosis of hard metal lung disease must be considered in a worker exposed to cobalt presenting with interstitial fibrosis.

To relate the ultrastructure of unmyelinated afferents to the cat carotid body with the known electrophysiological properties of cat chemosensory C-fibers, we took advantage of the fact that the calcitonin gene-related peptide is exclusively present in a population of sparsely branched afferents to the carotid body. They have a morphology identical to the afferents originating from carotid sinus nerve unmyelinated axons. Immunoreactive axons were stained using pre-embedding protocols and horseradish peroxidase-labeled secondary antibody. Labeling was present only in unmyelinated axons and boutons distributed in the interstitial and parenchymal tissue. The varicosities had an average diameter of 0.7 micron, and contained both small, clear vesicles and larger dense-core vesicles. No labeled axons were ever seen to contact glomus cells, but could be observed as close as 0.2 micron to a glomus cell, always with an interposed glial process. With a very sensitive protocol, that used tungstate-stabilized tetramethylbenzidine as the chromogen, amorphous deposits of reaction product were often detected in the extracellular space around a labeled bouton. We interpret these findings as indicating that the reciprocal chemical transmission between the oxygen-sensitive glomus cells and the unmyelinated afferents takes place through non-synaptic transmission, via the rather large extracellular space of the carotid body. In addition, the larger distances between glomus cells and unmyelinated afferents could explain the lowered sensitivity and sluggishness of chemosensory C-fibers, compared to the A-fibers.

We report here a case of localized fibrous pleural mesothelioma diagnosed in a sixty-year old patient, who had been exposed to tungsten carbide and asbestos dust for almost twenty years. He first consulted because of enduring lateral chest pains combined with progressive and increasing dyspnea on exertion. The initial diagnosis, after both pulmonary radiograph and computerised tomography, was confirmed by a histology which revealed fusiform cells of fibroblastic origin. After simple and total excision of the tumor, symptoms improved.