Stabilization of Si60 cage structure

A comprehensive search for the stable geometries of bare Si60 and Si60 supported on a C60 fullerene was carried out using first principles calculations based on density functional theory. In contrast to previous theoretical studies and in agreement with recent experiments, we show that Si60 and C(60)@Si(60) clusters are unstable in the fullerenelike cage structure. However, Si60 cage can be stabilized by including within it, as endohedral units, small magic clusters such as Al12X (X=Si, Ge, Sn, Pb) and Ba@Si(20).

Percutaneous tracheostomy

The purpose of this review is to discuss the various techniques of percutaneous tracheostomy and to assess their safety and efficacy profile, indications and contraindications, early and late complications. Literature was reviewed from Medline and MD Consult databases. Early techniques by Sheldon, toye and Schachner have been abandoned due to their high complication rates. Percutaneous dilational tracheostomy using the Ciaglia kit (Wiliam Cook Europe Bjaeverskov) and a Griggs kit (Portex PDT kit, POrtex, Hythe, Kent, UK) has been used most often. Griggs guide Wire Dilator Forceps kit (SIMS, Portex, Hythe, Kent, UK) is the next most common in use but its long-term studies are few. Fantoni (TLT set, Mallinckrodt Medical) and PercuTwist device (Riisch, Kernen, Germany) are two new techniques currently under study. Percutaneous dilational tracheostomy and conventional surgical tracheostomy are still competing methods to provide an airway for intensive care patient requiring assisted ventilation. Review of literature shows that percutaneous tracheostomy is safe, cost-effective and compares favourably with the open surgical tracheostomy. Many intensive care units now use the percutaneous tracheostomy as a procedure of choice. Percutaneous tracheostomy has a learning curve and requires appropriate case selection and meticulous attention to the technique by all those who want to use this method.

Giant magnetic moments of nitrogen-doped Mn clusters and their relevance to ferromagnetism in Mn-doped GaN

Calculations based on density-functional theory show that the stability and magnetic properties of small Mn clusters can be fundamentally altered by the presence of nitrogen. Not only are their binding energies substantially enhanced, but also the coupling between the magnetic moments at Mn sites remains ferromagnetic irrespective of their size or shape. In addition, these nitrogen-doped Mn clusters carry giant magnetic moments ranging from 4mu(B) in MnN to 22mu(B) in Mn5N. It is suggested that the giant magnetic moments of MnxN clusters may play a key role in the ferromagnetism of Mn-doped GaN which exhibit a wide range (10-940 K) of Curie temperatures.

Magic numbers in metallo-inorganic clusters: chromium encapsulated in silicon cages

A systematic theoretical study of the equilibrium geometries and total energies of Cr encapsulated in Si clusters reveals that Cr@Si(12) is more stable than its neighbors. The origin of this enhanced stability is consistent with the 18-electron sum rule commonly used in the synthesis of stable chemical complexes, and may provide a criterion for a systematic search of magic numbers in metalloinorganic clusters. The 6 mu(B) magnetic moment of the caged Cr atom, the largest among the 3d transition metal atoms, is completely quenched. This effect of caging on the properties of transition metal atoms may lead to the synthesis of novel cluster based materials.

Antihyperglycemic activity of Momordica cymbalaria in alloxan diabetic rats

Aqueous, ethanolic and hexane fractions of Momordica cymbalaria fruits were prepared and given individually at different doses to different batches of rats (both normal and alloxan diabetic rats) after an overnight fast. The blood glucose levels were measured at 0, 1, 3, 5 and 7 h after the treatment. The aqueous extract of Momordica cymbalaria at a dosage of 0.5 g/kg b.w. is showing maximal blood glucose lowering effect in diabetic rats. The same dosage did not produce any hypoglycemic activity in normal rats. The antihyperglycemic activity of Momordica cymbalaria fruit was compared with the treatment of Glibenclamide, an oral hypoglycemic agent.

Lipid peroxidation and antioxidant enzyme status in Type 2 diabetics with coronary heart disease

Lipid peroxides are thought to be formed by free radicals and may play an important role in the development of atheromatous vascular diseases. The relationship between serum lipids, lipoproteins, lipid peroxides [thiobarbituric acid reactive substances (TBARS)] and erythrocyte antioxidant enzymes [catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD)] was investigated in non-insulin-dependent diabetic patients with and without coronary heart disease (CHD), and a comparison was made for all the above parameters with non-diabetic patients with CHD. Lipid peroxide concentrations were significantly increased in both groups of diabetic patients and also in non-diabetic patients with CHD, compared to those in control subjects. Diabetic patients with CHD had higher levels of TBARS compared to those diabetics without CHD. Hyperlipidaemia and abnormal lipoprotein levels were observed in all three groups of patients. Increased total cholesterol and LDL-cholesterol were observed in diabetics with CHD compared to those without CHD. Among the erythrocyte antioxidant enzymes, CAT activity was increased, GPx activity was decreased and no change was observed in SOD activity in both groups of diabetic patients and non-diabetic patients with CHD compared to those in controls. A clear correlation was observed between the CAT activity and lipid peroxide concentrations in all the diabetic patients. These observations suggest that there are similar abnormalities in lipid metabolism and erythrocyte antioxidant enzymes in diabetic patients and non-diabetic patients with CHD.

Pyoderma vegetans

BACKGROUND

Pyoderma vegetans is a rare condition that is clinically characterized by large verrucous plaques with elevated borders and multiple pustules. The etiology of this disorder remains unknown.

OBJECTIVES

We describe a 24-year-old woman with rapidly evolving pyoderma vegetans. Our patient had the unique additional findings of a highly elevated serum IgE level and a history of hidradenitis suppurativa.

CONCLUSIONS

Pyoderma vegetans is diagnosed on clinical and histological criteria. Differentiation must be made from disorders such as pyoderma gangrenosum, Sweet's syndrome, and deep fungal infections. We illustrate a case of pyoderma vegetans and review the literature on this rare disorder. Clinical and histological criteria for diagnosis are presented, as well as differentiation from some mimicking disorders.

Electronic structure and properties of transition metal-benzene complexes

A comprehensive theoretical study of the geometries, energetics, and electronic structure of neutral and charged 3d transition metal atoms (M) interacting with benzene molecules (Bz) is carried out using density functional theory and generalized gradient approximation for the exchange-correlation potential. The variation of the metal-benzene distances, dissociation energies, ionization potentials, electron affinities, and spin multiplicities across the 3d series in MBz complexes differs qualitatively from those in M(Bz)(2). For example, the stability of Cr(Bz)(2) is enhanced over that of CrBz by almost a factor of 30. On the other hand, the magnetic moment of Cr(Bz)(2) is completely quenched although CrBz has the highest magnetic moment, namely 6 mu(B), in the 3d metal-benzene series. In multidecker complexes involving V(2)(Bz)(3) and Fe(2)(Bz)(3), the metal atoms are found to couple antiferromagnetically. In addition, their dissociation energies and ionization potentials are reduced from those in corresponding M(Bz)(2) complexes. All of these results agree well with available experimental data and demonstrate the important role the organic support can play on the properties of metal atoms/clusters.

Typical dermoscopic patterns of benign melanocytic nevi

Dermoscopy often is an effective diagnostic tool for differentiating benign and malignant pigmented skin lesions. The observed dermoscopic structures and patterns of lesions provide valuable sources of information that are not accessible by routine clinical examination. Recognition and interpretation of these dermoscopic structures and patterns require training and experience. Mentioned here are some fundamental guidelines for differentiating malignant and benign lesions. Some of the classic patterns associated with a list of benign melanocytic nevi also have been illustrated. Additional research is needed to identify other patterns of these benign lesions. More importantly, analysis of the prevalence of various patterns associated with the various benign lesions will be helpful to clinicians having the responsibility of making in vivo diagnoses of benign compared with malignant melanocytic neoplasms.

Hypoglycemic and antihyperglycemic activity of Syzygium alternifolium (Wt.) Walp. seed extracts in normal and diabetic rats

Aqueous, ethanolic and hexane fractions of Syzygium alternifolium seeds were prepared and given different doses of these extracts individually to different batches of rats (both normal and alloxan diabetic rats) after an overnight fast. The blood glucose levels were measured at 0, 1, 3, 5 and 7 hours after the treatment. The aqueous extract of Syzygium alternifolium at a dosage of 0.75 g/kg b.w. is showing maximum blood glucose lowering effect in both normal and alloxan diabetic rats. The ethanol and hexane fractions are also showing hypoglycemic and antihyperglycemic activity, but the effect is significantly less than that of aqueous extract. The antihyperglycemic activity of Syzygium alternifolium seed was compared with the treatment of Glibenclamide.

AlH(3) and Al(2)H(6): magic clusters with unmagical properties

Enhanced stability, low electron affinity, and high ionization potential are the hallmarks of a "magic" cluster. With an electron affinity of 0.28 eV, ionization potential of 11.43 eV, and a large binding energy, AlH(3) satisfies these criteria. However, unlike other magic clusters that interact only weakly with each other, two AlH(3) clusters bind to each other with an energy of 1.54 eV. The resulting Al(2)H(6), while also a magic cluster in its own right, possesses the most unusual property that the difference between its adiabatic and vertical detachment energy is about 2 eV--the largest of any known cluster. These results, based on density functional theory, are verified experimentally through photodetachment spectroscopy.

A case of cutaneous Mycobacterium chelonae abscessus infection in a renal transplant patient

BACKGROUND

Mycobacterium chelonae is an atypical "fast-growing Mycobacteria" that is a rare cause of human infection. There have been several reports of cutaneous infection among immunosuppressed patients, as well as in immunocompetent individuals following trauma. Most cases to date seem to have occurred among renal transplant recipients, raising the possibility that there is something inherent to the renal transplant patient that increases their susceptibility more than other immunocompromised patients.

OBJECTIVE

The differential diagnosis of subcutaneous nodules distributed in a sporotrichoid pattern is extensive, particularly in an immunocompromised host. Although several cases of cutaneous M. chelonae abscessus infection have been reported among both immunosuppressed and immunocompetent patients, the clinical presentation has varied, and few cases have reported the appearance of lesions in a sporotrichoid pattern. We present a case of a renal transplant patient with a reported history of trauma to the lower extremities, who presents with subcutaneous nodules distributed in a sporotrichoid pattern. The patient is found to have M. chelonae abscessus infection, fails several treatment regimens, and presents with a recurrence. The literature of M. chelonae infection is reviewed, and the various treatment options are discussed.

METHODS

An initial skin biopsy was stained with Hematoxylin and Eosin and revealed deep dermal abscesses with acid-fast bacilli in clusters. The culture became positive for Mycobacterium chelonae abscesses in four days and was found to be sensitive to multiple antibiotics. The patient underwent surgical excision of 14 nodules, which revealed findings consistent with the skin biopsy, and was subsequently treated with the appropriate antibiotics.

RESULTS

Despite treatment with a full course of an organism-sensitive antibiotic regimen, the patient returned with persistent and recurrent nodules six weeks later. The patient was then treated as an inpatient with a seven-week course of intravenous antibiotics and was discharged home on a combined intravenous and oral regimen.

CONCLUSION

Although M. chelonae abscessus is an extremely rare cause of infection among humans, there seems to be a predominance of cases reported among renal transplant patients. The explanation for this is not entirely clear; however, the organism must be considered as a cause of infection in any renal transplant recipient who presents with subcutaneous nodules. Eradication of the organism presents a tremendous challenge to the clinician, and, as presented here, even with appropriate antibiotics, there is a high rate of recurrence.