Alteration of the electronic structure and the optical properties of graphitic carbon nitride by metal ion doping.

The photoluminescence quenching of graphitic carbon nitride (GCN) was systematically investigated with the doping of transition metal ions. The photoluminescence spectra of metal doped and pristine GCN were monitored and the trend of quenching efficiency was found to be Cu2+ > Co2+ > Mn2+. Interestingly, with the increasing doping concentration of different metal ions simultaneous red shift and luminescence quenching was determined in the photoluminescence spectra as well as increased absorption tail in longer wavelength hence enhancement in the bandgap. The change in the optical properties could be mainly due to structural reconstruction and doping induced electronic redistribution is discussed.

Aspergillus pacemaker lead endocarditis.

A 47-year-old man who had a pacemaker implanted 2 years earlier, recently developed a fever and had been on antibiotics for 2 months. He presented with pulmonary emboli, and underwent lead extraction and emboli removal. Histopathology demonstrated Aspergillus. Amphotericin B was continued postoperatively. This rare case of pacemaker lead endocarditis suggests that vigorous medical and surgical intervention can be curative.

Association between periurethral colonization with uropathogens and subsequent bacteriuria in catheterized patients.

OBJECTIVE: To determine the number of catheterized patients who develop bacteriuria due to the presence of organisms in their periurethral flora, which may subsequently cause Urinary Tract Infection (UTI) in these patients. STUDY DESIGN: Non-interventional, cohort study. PLACE AND DURATION OF STUDY: This study was conducted on patients of Medical Intensive Care, Surgical and Urology Units of Combined Military Hospital, Lahore, from February to April 2006. METHODOLOGY: A total of 60 hospitalized patients, who were catheterized for various underlying diseases, were included in the study. Urine samples and periurethral swabs were obtained from all patients and cultured on appropriate culture media. Various tests used for the identification of microorganisms were: Gram-staining, catalase test, coagulase test and esculin hydrolysis for the identification of Gram-positive bacteria, API 20e for Gram-negative bacilli, whereas lactophenol blue preparation and germ tube test were used for the identification of yeasts. RESULTS: Out of 60 patients, 41(68.3%) were males and 19 (31.7%) were females. The mean duration of catheterization was 4.5 days. In males, culture of periurethral swabs revealed coagulase negative staphylococci in 11 (40.7%), Staphylococcus aureus in 10 (37%) and Enterococcus fecalis in 3 (11.1%) patients. In females, the organisms isolated were coagulase negative staphylococci in 4 (25%), Staphylococcus aureus in 4 (25%), Enterococcus fecalis in 4 (25%), Pseudomonas aeruginosa in 2 (12.5%), Escherichia coli in 3 (18.6%) and Candida albicans in 3 (18.6%) patients. Twenty nine patients developed bacteriuria (p < 0.05). Escherichia coli was the commonest organism causing bacteriuria in either gender followed by other Gram-negative organisms. Coagulase negative Staphylococcus was isolated in the urine of one male patient only. In males, 2 (10%) out of 20 patients with Gram-negative bacteriuria were colonized by the same organism, whereas in females, 4 (44.4%) out of 9 bacteriuric patients were colonized by the same organism. CONCLUSION: Predominantly Gram-positive organisms colonized the periurethral area in males as well as in the majority of females, whereas Gram-negative bacteria were mainly responsible for the bacteriuria in both genders. There was a significant association between periurethral colonization and subsequent bacteriuria, however, prior colonization with a particular organism is not a decisive event in the initiation of bacteriuria.

Mitral valve replacement in severe pulmonary arterial hypertension.

The immediate postoperative hemodynamics in 43 patients with severe pulmonary arterial hypertension who underwent mitral valve replacement between January 2000 and September 2001 were studied prospectively. The mean age was 30.6 years. There was mitral stenosis in 19 (44.1%), mitral regurgitation in 9 (20.9%), and mixed lesions in 15 (34.9%). In 36 patients (83.7%, group 1) pulmonary arterial pressure was sub-systemic, with a mean of 58.1 mm Hg and pulmonary vascular resistance of 743.4 dyne x s x cm(-5). Seven patients (16.3%, group 2) had supra-systemic pulmonary arterial pressure of 83.2 mm Hg and pulmonary vascular resistance of 1,529 dyne x s x cm(-5). Lung biopsies were taken from the right lower lobe in 24 patients. Operative mortality was 5.5% in group 1 and 28.5% in group 2. After mitral valve replacement, the pulmonary arterial pressure and vascular resistance decreased significantly in group 1. In group 2, pulmonary arterial pressure decreased significantly but pulmonary vascular resistance remained elevated. Pulmonary vascular changes did not progress beyond grade III (Heath-Edwards' classification). Mitral valve replacement is safe even in the presence of severe pulmonary arterial hypertension as long as pulmonary arterial pressures are below systemic pressures. Lung biopsy did not help in identifying patients with irreversible pulmonary arterial changes.