Fulminant meningococcal sepsis in a young child--a case report

We are presenting a case of isolated fulminant meningococcal sepsis with two and a half year old child. Initial symptoms were obscure and common to many medical conditions, but also previously described as symptoms of meningococcal sepsis. Unrecognizing the seriousness of the condition child died at home, within few hours after examination and discharge from the hospital. Autopsy and microbiological findings unquestionably proved that the child died from septic shock caused by fulminant meningococcal sepsis.     

Right atrial pacemaker lead thrombosis incidentally detected by transesophageal echocardiography

In a 62-year-old man with permanent atrial fibrillation and recurrent stroke, a large right atrial thrombus attached to a permanent pacemaker lead was incidentally identified by transesophageal echocardiography. Surgical treatment, recommended because of the large dimensions of the mass, was refused by the patient, and thrombus was successfully dissolved by anticoagulant treatment. Pathogenesis of pacemaker lead thrombosis, clinical implications, diagnostic and therapeutic options are discussed.     

Site-specific mutagenesis of the histidine precursor of diphthamide in the human elongation factor-2 gene confers resistance to diphtheria toxin

Protein synthesis elongation factor 2 (EF-2) from eukaryotes contains a conserved post-translationally modified histidine residue known as diphthamide. Diphthamide is a unique site of ADP-ribosylation by diphtheria toxin (DT), which is responsible for cell killing. In this report, we describe the construction of DT-resistant HeLa cell lines by engineering the toxin-resistant form of its specific substrate, protein elongation factor-2. Using site-specific mutagenesis of the histidine precursor of diphthamide, the histidine residue of codon 715 in human EF-2 cDNA was substituted with one of four amino acid residue codons: leucine, methionine, asparagine or glutamine. Mutant EF-2s were subcloned into a pCMVexSVneo expression vector, transfected into HeLa cells, and DT-resistant cell clones were isolated. The protective effect of mutant EF-2s against cell killing by DT, after exposing all four mutant strains derived from HeLa cells to different concentrations of the toxin (5-20 ng/mL) was demonstrated by: (1) the normal morphological appearance of the cells; (2) their unaffected or slightly slower growth rates; (3) their undisturbed electrophoretic DNA profiles whose integrity was virtually preserved. Mutant cell strains showed also considerable levels of resistance to very high concentrations of DT, in that they maintained slower but consistent rates of cell growth. It was hence concluded that despite its strict conservation and unique modification, the diphthamide histidine appears not to be essential to the function of human EF-2 in protein synthesis. In addition, DT-resistant HeLa cell clones should prove valuable hosts for various DT gene-containing vectors that express the toxin intracellularly.     

Analysis of the compressive strain below the removable and fixed prosthesis in the posterior mandible using a digital image correlation method

It was the purpose of this study to determine and analyse strains in the bone of posterior mandible below the removable and fixed partial dentures using Digital Image Correlation Method. Dried mandible with shortened dental arch (Kennedy Class 1) was used in the experiment. The mandible model was prepared for accepting two types of restorations for bilaterally missing molars conventional therapy, and removable and fixed partial dentures were manufactured following standard prosthetic protocol. The models with prosthetic restorations placed in situ were subjected to loading of 50-300 N, and photographed using two digital cameras as part of the digital image correlation method equipment. Afterwards, the obtained data for strains within restored mandible during loading ciclus were analysed in the software Aramis and graphically presented. Percentage size of the mandible strains within the line section are from 0.14 to 0.19% for the removable partial denture experimental model and 0-0.14% for the fixed partial denture experimental model. The study has demonstrated that Digital Image Correlation method can be used to measure strain on the mandible surface and replacements during loading and that from biomechanical perspective both therapeutic modalities can be equally useful for the restoration of the mandible with bilaterally distal edentulous spaces.     

The role of intrinsic muscle flaps of the foot for bone coverage in foot and ankle defects in diabetic and nondiabetic patients

Local muscle flaps, pioneered by Ger in the late 1960s, were extensively used for foot and ankle reconstruction until the late 1970s when, with the evolution of microsurgery, microsurgical free flaps became the reconstructive method of choice. To assess whether the current underuse of local muscle flaps in foot and ankle surgery is justified, the authors identified from the Georgetown Limb Salvage Registry all patients who underwent foot and ankle reconstruction with local muscle flaps and microsurgical free flaps from 1990 through 1998. By protocol, flap coverage was the reconstructive choice for defects with exposed tendons, joints, or bone. Local muscle flaps were selected over free flaps if the defect was small (3 x 6 cm or less) and within reach of the local muscle flap. During the same time frame, the authors performed 45 free flaps (96 percent success rate) in the same areas when the defects were too large or out of reach of local muscle flaps. Thirty-two consecutive patients underwent local muscle flap reconstruction for 19 diabetic wounds and 13 traumatic wounds. All wounds, after debridement, had exposed bone at their base, with osteomyelitis being present in 52 percent of the diabetic wounds and in 70 percent of the nondiabetic wounds. Wounds were located in the hindfoot (47 percent), midfoot (44 percent), and ankle (9 percent). Vascular disease was more prevalent in the diabetic group, in which 42 percent of the affected limbs required revascularization procedures before reconstruction (versus 7 percent in the nondiabetic group). Subsequently, 83 total operations were required to heal the wounds, of which 46 percent were limited to debridement only. Thirty-four pedicled muscle flaps were used: 19 abductor digiti minimi (56 percent), nine abductor hallucis (26 percent), three extensor digitorum brevis (9 percent), two flexor digitorum brevis (6 percent), and one flexor digiti minimi (3 percent). An additional skin graft for complete coverage was required in 18 patients (53 percent). One patient died and one flap developed distal necrosis, for a 96 percent success rate. The complication rate was 26 percent and included patient death, dehiscence, and partial flap or split-thickness skin graft loss. Twenty-nine of the 32 wounds healed. One patient died in the postoperative period; in two others the wounds failed to heal and required below-knee amputations, for an overall limb salvage rate of 91 percent. Diabetes did not significantly affect healing and limb salvage rates. Diabetes, however, did affect healing times (twofold increase), length of stay (2.7 times as long), and long-term survival (63 percent survival in diabetic patients versus 100 percent in the trauma group). Local muscle flaps provide a simpler, less expensive, and successful alternative to microsurgical free flaps for foot and ankle defects that have exposed bone (with or without osteomyelitis), tendon, or joint at their base. Diabetes does not appear to adversely affect the effectiveness of these flaps. Local muscle flaps should remain on the forefront of possible reconstructive options when treating small foot and ankle wounds that have exposed bone, tendon, or joint.     

Evaluation of genotoxic effects of fumagillin by cytogenetic tests in vivo

Fumagillin is a naturally secreted antibiotic of the fungus Aspergillus fumigatus. It is used in veterinary medicine against microsporidiosis of bees and fish. In this study, the genotoxicity of fumagillin (in the form of fumagillin dicyclohexylamine) was evaluated in mouse bone-marrow cells using the mitotic index (MI), the chromosome aberration (CA) assay, and the micronucleus (MN) test. Fumagillin was administered to BALB/c mice by gavage, at doses of 25, 50, 75 mg/kg body weight (bw), repeated for 7 days at 24-h intervals, with water-sugar syrup as a negative control and cyclophosphamide (40 mg/kg bw) as a positive control. All experimental doses of fumagillin induced a significant decrease (p<0.001) in MI (3.47+/-0.04%, 3.17+/-0.01%, and 2.27+/-0.02%, respectively) in comparison with the negative control (6.00+/-0.01%). Fumagillin significantly (p<0.001) increased the frequency of MN (4.98+/-0.35, 8.45+/-0.57, and 12.02+/-0.37, respectively) over negative control (1.04+/-0.28). Significantly increased frequencies (p<0.01 or p<0.001) of numerical chromosomal aberrations (aneuploidies and polyploidies) and structural chromosomal aberrations such as gaps, breaks, and centric rings were observed at the highest experimental dose of fumagillin (75 mg/kg bw) compared with the negative control. However, with respect to the induction of Robertsonian translocations, both the intermediate (50 mg/kg bw) and highest (75 mg/kg bw) experimental dose caused a significant (p<0.001) increase (7.12+/-0.26 and 9.00+/-0.10, respectively) in comparison with the negative control (0.00+/-0.00). Chromosomes 4 and 19 participated in these Robertsonian translocations. Regarding total cytogenetic changes, a significant increase (p<0.001) was observed in both the intermediate dose group (17.36+/-1.83) and the highest dose group (59.49+/-1.92) compared with the negative control (7.00+/-1.35). These results suggest that fumagillin has genotoxic (clastogenic) potential in mammals in vivo.     

The mycorrhizal status of the woody Mediterranean shrub Myrtus communis L.

  Myrtus communis L. (myrtle), a typical Mediterranean plant species belonging to the family Myrtaceae, was shown to form arbuscular mycorrhizal symbioses in nature. Many different spore types were isolated from its rhizosphere and grown in pot cultures; six of them were identified as Glomus species. In the laboratory, the myrtle root system was colonized by indigenous endophytes as well as by an Italian isolate of Glomus intraradices. In greenhouse experiments, mycorrhizal inoculation reduced transplant stress in 60-day-old myrtle seedlings; their growth was renewed immediately after transplanting, whereas non-mycorrhizal plants stopped development. Significantly larger growth responses were obtained using indigenous fungi than the Italian isolate of Glomus intraradices. Accepted: 16 January 1997     

Subplate zone of the human brain: historical perspective and new concepts

Subplate zone (SP) is prominent, transient laminar compartment of the human fetal cerebral wall. The SP develops around 13 and gradually disappears after 32-34 postovulatory weeks. The SP neurons can be found as late as nine postnatal months, while remnants of the SP neurons can be traced until adult age in the form of interstitial neurons of the gyral white matter. SP is composed of postmigratory and migratory neurons, growth cones, loosely arranged axons, dendrites, glial cell and synapses. The remarkable feature of the SP is the presence of large amount of extracellular matrix. This feature can be used for delineation of SP in magnetic resonance images (MRI) of both, in vivo and post mortem brains. The importance of SP as the main synaptic zone of the human fetal cortex is based on the rich input of ,waiting,< afferents from thalamus and cortex, during the crucial phase of cortical target area selection. SP increases during mammalian evolution and culminates in human brain concomitantly with increase in number and diversity of cortico-cortical fibers. The recent neurobiological evidence shows that SP is important site of spontaneous endogeneous activity, building a framework for development of cortical columnar organization. The SP which can be readily visualized on conventional and DTI (diffusion-tensor-imaging) MRI in vivo, today is in the focus of interest of pediatric neurology due to the following facts: (1) SP is the site of early neural activity, (2) SP is the major substrate for functional plasticity, and (3) selective vulnerability of SP may lead to cognitive impairment.     

Conservation priorities of genetic diversity in domesticated metapopulations: a study in taurine cattle breeds

We estimated neutral diversity of 21 European cattle breeds with 105 microsatellites. Nine of them resembled unselected Balkan Buša strains with diffuse breeding barriers and the 12 others were strongly differentiated, isolated breeds. Because of the impact of neutral genetic diversity on long-term population adaptive capacity, we discuss the long-term outcome of different conservation priorities in a subdivided metapopulation of the investigated cattle breeds. The optimal contribution to a pool of total genetic diversity allocated more than 95% of long-term relevant neutral diversity to virtually unselected strains of the Balkan Buša, while the maximization of total variance preferred inbred breeds. Current artificial selection methods, such as genomic selection sped up and a recovery of underestimated traits becomes quickly impossible. We emphasize that currently neutral and even deleterious alleles might be required for future genotypes in sustainable and efficient livestock breeding and production systems of a 21st century. We provide cumulative evidences that long-term survival relies on genetic complexity and complexity relies on allelic diversity. Our results suggest that virtually unselected, nonuniform strains harbor a crucial proportion of neutral diversity and should be conserved with high global priority. As one example, we suggest a cooperative maintenance of the nondifferentiated, highly fragmented, and fast vanishing metapopulation of Balkan Buša.