Splenic abscesses in childhood brucellosis: a case-based review.

OBJECTIVE: Human brucellosis is a zoonosis with an extremely wide spectrum of clinical manifestations. Focal splenic involvement is very uncommon, particularly in the pediatric age group, during the illness' acute phase. CASE REPORT: A 4-year-old boy, already receiving third-generation cephalosporin treatment, was transferred from a local hospital to the University Pediatric Department for fever, anemia, increased inflammation index, and multiple, hyper-echogenic splenic lesions on abdominal ultrasound. Initial diagnostic laboratory investigations for Brucella infection, including the Widal-Wright test, were found to be negative. However, further diagnostic laboratory analysis using the chemiluminescent immunoassay was positive for Brucella IgM antibodies. Treatment with rifampicin at a dose of 150 mg/Kg/twice daily and co-trimethoprim at a dose of 80 mg/Kg/twice daily was started and continued for 7 weeks. IgM antibodies were undetectable after 2 weeks of treatment, and after 6 weeks of treatment, abdominal ultrasound documented a reduction of the diameter of the major splenic infiltrate from 1 to 0.5 cm. At 3 and 5 months of follow-up, re-evaluation of the abdominal lesions displayed complete resolution of the splenic lesions and a complete clinical recovery. CONCLUSIONS: The present case and a literature review are presented in this study since a standard diagnostic laboratory evaluation for brucellosis may miss the diagnosis, and in suspected cases, the laboratory analysis should be extended. Splenic abscesses are known to be rare in brucellosis, but the diagnosis should be considered in children with severe focal lesions, as specific antibiotic treatment may result in complete clinical recovery.

Neurofibromatosis type 2 discordance in monozygous twins.

Neurofibromatosis type 2 (NF2) is an autosomal dominant condition caused by pathogenic variants in the NF2 gene. The pathogenic variant is either inherited or obtained by de novo mutation, characterised by the presence of schwannomas, meningiomas and ependymomas. Here we report the presence of NF2 in one twin, with bilateral vestibular schwannomas and a pathogenic variant of the NF2 gene identified in both tumour and lymphocytes, while his monozygous brother remains asymptomatic. Imaging of the unaffected twin showed no tumour load and genetic testing via Sanger sequencing and Amplification Refractory Mutation System assay demonstrated low levels of expression of the NF2 variant in lymphocytes. Further testing on non-haemopoietic tissue showed little expression or absence of the pathogenic variant. Given there is no family history and the low level of the variant, we assume the pathogenic variant is a de novo mutation during embryogenesis. De novo mutations have been described as occurring at three possible time points in the creation of monozygous twins with different genetic make-up; prior to the twinning event, as a cause of the event, or after the twinning event. Of these options, we hypothesise that the discordance in the expression of the NF2 variant between these twins is likely due to a mutational event that occurred as a result of either of the latter two possibilities, between which we cannot determine. The pathogenic variant in lymphocytes was likely transferred between the twins through a shared blood supply in utero, and the non-haemopoietic samples that showed low levels of expression, were likely due to the presence of lymphocytic cells. Therefore, we have a discordance between monozygous twins at the NF2 gene.

Surface ruptures database related to the 26 December 2018, MW 4.9 Mt. Etna earthquake, southern Italy.

We provide a database of the surface ruptures produced by the 26 December 2018 Mw 4.9 earthquake that struck the eastern flank of Mt. Etna volcano in Sicily (southern Italy). Despite its relatively small magnitude, this shallow earthquake caused about 8 km of surface faulting, along the trace of the NNW-trending active Fiandaca Fault. Detailed field surveys have been performed in the epicentral area to map the ruptures and to characterize their kinematics. The surface ruptures show a dominant right-oblique sense of displacement with an average slip of about 0.09 m and a maximum value of 0.35 m. We have parsed and organized all observations in a concise database, with 932 homogeneous georeferenced records. The Fiandaca Fault is part of the complex active Timpe faults system affecting the eastern flank of Etna, and its seismic history indicates a prominent surface-faulting potential. Therefore, this database is essential for unravelling the seismotectonics of shallow earthquakes in volcanic areas, and contributes updating empirical scaling regressions that relate magnitude and extent of surface faulting.

Kinetics and energetics of ligand binding determined by microcalorimetry: insights into active site mobility in a psychrophilic alpha-amylase.

A new microcalorimetric method for recording the kinetic parameters k(cat), K(m) and K(i) of alpha-amylases using polysaccharides and oligosaccharides as substrates is described. This method is based on the heat released by glycosidic bond hydrolysis. The method has been developed to study the active site properties of the cold-active alpha-amylase produced by an Antarctic psychrophilic bacterium in comparison with its closest structural homolog from pig pancreas. It is shown that the psychrophilic alpha-amylase is more active on large macromolecular substrates and that the higher rate constants k(cat) are gained at the expense of a lower affinity for the substrate. The active site is able to accommodate larger inhibitory complexes, resulting in a mixed-type inhibition of starch hydrolysis by maltose. A method for recording the binding enthalpies by isothermal titration calorimetry in a low-affinity system has been developed, allowing analysis of the energetics of weak ligand binding using the allosteric activator chloride. It is shown that the low affinity of the psychrophilic alpha-amylase for chloride is entropically driven. The high enthalpic and entropic contributions of activator binding suggest large structural fluctuations between the free and the bound states of the cold-active enzyme. The kinetic and thermodynamic data for the psychrophilic alpha-amylase indicate that the strictly conserved side-chains involved in substrate binding and catalysis possess an improved mobility, responsible for activity in the cold, and resulting from the disappearance of stabilizing interactions far from the active site.

Cold-adapted enzymes from marine Antarctic microorganisms.

The Antarctic marine environment is characterized by challenging conditions for the survival of native microorganisms. Indeed, next to the temperature effect represented by the Arrhenius law, the viscosity of the medium, which is also significantly enhanced by low temperatures, contributes to slow down reaction rates. This review analyses the different challenges and focuses on a key element of life at low temperatures: cold-adapted enzymes. The molecular characteristics of these enzymes are discussed as well as the adaptation strategies which can be inferred from the comparison of their properties and three-dimensional structures with those of their mesophilic counterparts. As these enzymes display a high specific activity at low and moderate temperatures associated with a relatively high thermosensitivity, the interest in these properties is discussed with regard to their current and possible applications in biotechnology.

Fascicular nerve stimulation and recording using a novel double-aisle regenerative electrode.

OBJECTIVE: As artificial prostheses become more refined, they are most often used as a therapeutic option for hand amputation. By contrast to extra- or intraneural interfaces, regenerative nerve electrodes are designed to enable electrical interfaces with regrowing axonal bundles of injured nerves, aiming to achieve high selectivity for recording and stimulation. However, most of the developed designs pose an obstacle to the regrowth mechanisms due to low transparency and cause impairment to the nerve regeneration. APPROACH: Here we present the double-aisle electrode, a new type of highly transparent, non-obstructive regenerative electrode. Using a double-side thin-film polyimide planar multi-contact electrode, two nerve fascicles can regenerate without physical impairment through two electrically isolated aisles. MAIN RESULTS: We show that this electrode can be used to selectively record and stimulate fascicles, acutely as well as chronically, and allow regeneration in nerve gaps of several millimeters without impairment. SIGNIFICANCE: This multi-aisle regenerative electrode may be suitable for neuroprosthetic applications, such as prostheses, for the restoration of hand function after amputation or severe nerve injuries.

Submassive acute pulmonary thromboembolism with normal D-dimer. A case report.

Pulmonary thromboembolism is a relatively common disease in an Emergency Department. Diagnosis, often difficult, is based on careful evaluation of risk factors, clinical examination, radiological and laboratory investigations. Plasma D-dimer, a degradation product of cross-linked fibrin with low specificity and very high sensibility, is considered extremely useful as screening to rule out a pulmonary thromboembolism. We report the case of a 74 year old woman who presented in the Emergency Department suffering from the sudden onset of dyspnea 4 hours before. Plasma D-dimer (automated latex-enhanced turbidimetric test) was normal (253 ng/mL; normal value: 278 ng/mL), but spiral CT angiography showed a sub-massive thromboembolism of the principal branch of the right pulmonary artery, also involving the middle and the inferior lobar branches. A cardiac echo-color-Doppler demonstrated an enlargement of the right cardiac section with telediastolic pressure in the pulmonary artery of 74 mmHg (normal value 4-12 mmHg). A second measurement of plasma D-dimer, 12 hours later, remained in the normal range (274 ng/mL) and only after four days was there a significant increase (1017 ng/mL). The authors, taking the case as a starting point, stigmatize the difficulties that such diagnosis involves, despite indications of guidelines.

Some like it cold: biocatalysis at low temperatures.

In the last few years, increased attention has been focused on a class of organisms called psychrophiles. These organisms, hosts of permanently cold habitats, often display metabolic fluxes more or less comparable to those exhibited by mesophilic organisms at moderate temperatures. Psychrophiles have evolved by producing, among other peculiarities, "cold-adapted" enzymes which have the properties to cope with the reduction of chemical reaction rates induced by low temperatures. Thermal compensation in these enzymes is reached, in most cases, through a high catalytic efficiency associated, however, with a low thermal stability. Thanks to recent advances provided by X-ray crystallography, structure modelling, protein engineering and biophysical studies, the adaptation strategies are beginning to be understood. The emerging picture suggests that psychrophilic enzymes are characterized by an improved flexibility of the structural components involved in the catalytic cycle, whereas other protein regions, if not implicated in catalysis, may be even more rigid than their mesophilic counterparts. Due to their attractive properties, i.e., a high specific activity and a low thermal stability, these enzymes constitute a tremendous potential for fundamental research and biotechnological applications.

Experimental investigation of various vegetable fibers as sorbent materials for oil spills.

Oil spills are a global concern due to their environmental and economical impact. Various commercial systems have been developed to control these spills, including the use of fibers as sorbents. This research investigates the use of various vegetable fibers, namely mixed leaves residues, mixed sawdust, sisal (Agave sisalana), coir fiber (Cocos nucifera), sponge-gourd (Luffa cylindrica) and silk-floss as sorbent materials of crude oil. Sorption tests with crude oil were conducted in deionized and marine water media, with and without agitation. Water uptake by the fibers was investigated by tests in dry conditions and distillation of the impregnated sorbent. The silk-floss fiber showed a very high degree of hydrophobicity and oil sorption capacity of approximately 85goil/g sorbent (in 24hours). Specific gravity measurements and buoyancy tests were also used to evaluate the suitability of these fibers for the intended application.

Cold-adapted enzymes: from fundamentals to biotechnology.

Psychrophilic enzymes produced by cold-adapted microorganisms display a high catalytic efficiency and are most often, if not always, associated with high thermosensitivity. Using X-ray crystallography, these properties are beginning to become understood, and the rules governing their adaptation to cold appear to be relatively diverse. The application of these enzymes offers considerable potential to the biotechnology industry, for example, in the detergent and food industries, for the production of fine chemicals and in bioremediation processes.

Structural similarities and evolutionary relationships in chloride-dependent alpha-amylases.

The alpha-amylase sequences contained in databanks were screened for the presence of amino acid residues Arg195, Asn298 and Arg/Lys337 forming the chloride-binding site of several specialized alpha-amylases allosterically activated by this anion. This search provides 38 alpha-amylases potentially binding a chloride ion. All belong to animals, including mammals, birds, insects, acari, nematodes, molluscs, crustaceans and are also found in three extremophilic Gram-negative bacteria. An evolutionary distance tree based on complete amino acid sequences was constructed, revealing four distinct clusters of species. On the basis of multiple sequence alignment and homology modeling, invariable structural elements were defined, corresponding to the active site, the substrate binding site, the accessory binding sites, the Ca(2+) and Cl(-) binding sites, a protease-like catalytic triad and disulfide bonds. The sequence variations within functional elements allowed engineering strategies to be proposed, aimed at identifying and modifying the specificity, activity and stability of chloride-dependent alpha-amylases.

Metastatic calcification in the thyroid gland demonstrated on bone scan in a patient with primary hyperparathyroidism.

Bone scanning agents are known to accumulate in extraskeletal sites. We report the case of a patient with primary hyperparathyroidism whose bone scan performed with [99mTc]HMDP revealed not only the classic pattern described in hyperparathyroidism, but also a striking visceral uptake in the lungs, heart, stomach, and thyroid gland. Metastatic calcification was found on histologic examination of the thyroid.

Levofloxacin versus ciprofloxacin versus lomefloxacin in acute pyelonephritis.

OBJECTIVES: To evaluate, in two randomized, multicenter trials, levofloxacin compared with ciprofloxacin and lomefloxacin for efficacy and safety in treating acute pyelonephritis. METHODS: We enrolled a total of 186 patients with bacteriologically proved infection. Of these, 89 patients in both trials combined received levofloxacin 250 mg once daily; 58 received ciprofloxacin 500 mg twice daily in the first trial (double blind); and 39 received lomefloxacin 400 mg once daily in the second trial (open label). Microbiologic response of patients evaluable for microbiologic efficacy was the primary efficacy variable, and clinical response of microbiologically evaluable patients was the secondary efficacy variable in both studies. RESULTS: Escherichia coli was the most prevalent pathogen. At 5 to 9 days after the end of treatment, 95% of uropathogens were eradicated in patients who received levofloxacin compared with 94% in the ciprofloxacin-treated group and 95% in the lomefloxacin-treated group. The clinical cure rate was 92% for levofloxacin in both studies combined, 88% for ciprofloxacin, and 80% for lomefloxacin. Drug-related adverse events were reported by 2% of levofloxacin-treated patients, 8% of ciprofloxacin-treated patients, and 5% of lomefloxacin-treated patients. CONCLUSIONS: The once-daily oral administration, proven efficacy, and good tolerability make levofloxacin an excellent choice for empiric treatment of acute pyelonephritis.

A controlled trial of levofloxacin and lomefloxacin in the treatment of complicated urinary tract infection.

OBJECTIVES: The efficacy and safety of levofloxacin and lomefloxacin in complicated urinary tract infections (UTIs) were compared in a randomized, open-label, multicenter study. METHODS: Outpatients were randomized to receive levofloxacin (250 mg once daily) for 7 to 10 days or lomefloxacin (400 mg once daily) for 14 days. Three hundred thirty-six patients (171 with levofloxacin, 165 with lomefloxacin) were evaluable for microbiologic efficacy, and 461 patients (232 with levofloxacin, 229 with lomefloxacin) for safety. RESULTS: The overall microbiologic eradication rate of pathogens was 95.5% (168 of 176) for levofloxacin and 91.7% (154 of 168) for lomefloxacin. Eradication rates with respect to patients were 95.3% (163 of 171) and 92.1% (152 of 165) for levofloxacin and lomefloxacin, respectively. At the 5 to 9-day post-therapy visit, symptoms were completely resolved in 84.8% of levofloxacin-treated patients and were decreased in 8.2% (93.0% clinical success). Among the lomefloxacin-treated patients, complete resolution was seen in 82.4%, with decreased symptoms in 6.1% (88.5% clinical success). Drug-related adverse events (AEs) were reported by 10 (2.6%) and 18 (5.2%) levofloxacin- and lomefloxacin-treated patients, respectively. Compared with levofloxacin-treated patients, more lomefloxacin-treated patients experienced photosensitivity reactions (3 [1.3%] versus 0) and dizziness (2 [0.9%] versus 0). Nausea (3 [1.3%] versus 1 [0.4%]) was more frequent in the levofloxacin-treated group. Six patients in each treatment group had a gastrointestinal AE (1.7%); rash was reported more frequently with lomefloxacin (4 patients [0.4%]) than with levofloxacin (1 patient [0.4%]). Discontinuation because of AEs was observed in 8 (3.4%) levofloxacin- and 14 (6.1%) lomefloxacin-treated patients. CONCLUSIONS: Once-daily levofloxacin is as effective as and has a superior tolerability profile than lomefloxacin in the treatment of complicated UTIs.