Interaction of bladder glycoprotein GP51 with uropathogenic bacteria

PURPOSE: A major component of bladder surface mucin is a glycoprotein GP51 (molecular weight 51 kD.). GP51, which has previously been isolated from rabbit mucosa, appears to function as part of the defense mechanism in an in vivo infection model. GP51 coats the epithelium and is secreted into the urine, as detected by immunohistochemical testing and enzyme-linked immunosorbent assay (ELISA). Increased urinary GP51 occurs during urinary tract infection. To elucidate the role of GP51 as a component of the primary defense mechanism we studied interactions with uropathogenic bacterial isolates and urine from symptomatic patients with urinary tract infection. MATERIALS AND METHODS: ELISA was performed to demonstrate the binding of GP51 and various uropathogens. Immunochemical studies were done using monoclonal antibodies to GP51 to determine the interaction of GP51 with certain uropathogenic isolates, including Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, S. epidermidis and Streptococcus faecalis. Infected urinary sediments and uropathogenic bacterial cultures were examined by immunocytochemical testing to localize GP51. Antigen inhibition ELISA was done to quantitate urinary GP51 in the urine of 17 normal controls and 19 patients with urinary tract infection. RESULTS: ELISA revealed that GP51 binds to a wide spectrum of gram-positive and gram-negative uropathogens in semiquantitative fashion. Immunochemical methods confirmed that purified GP51 binds to bacteria, encapsulating and aggregating the bacteria. Clinical specimens showed GP51 localized to bacteria and uroepithelial cells. We observed a significant increase in urinary GP51 in urinary tract infection compared to uninfected urine (p = 0.0003). CONCLUSIONS: These studies suggest that GP51, a component of bladder mucin, may be a strategic factor in the primary defense mechanism of the bladder.     

Massive pulmonary embolism: the place for embolectomy

Untreated massive pulmonary embolism is associated with a high mortality. Pulmonary embolectomy has been largely superceded by thrombolytic therapy, but there are cases in which pulmonary embolectomy remains the treatment of choice. We present three case reports and discuss the merits of the various treatments available for massive pulmonary embolism. The primary treatment of massive pulmonary embolism should be thrombolytic therapy, but for patients who are at risk of haemorrhage following surgery, who are in cardiogenic shock despite medical treatment, or fail to improve following cardiac arrest, then pulmonary embolectomy remains the treatment of choice.     

Standardized interpretation of paediatric chest radiographs for the diagnosis of pneumonia in epidemiological studies

BACKGROUND: Although radiological pneumonia is used as an outcome measure in epidemiological studies, there is considerable variability in the interpretation of chest radiographs. A standardized method for identifying radiological pneumonia would facilitate comparison of the results of vaccine trials and epidemiological studies of pneumonia. METHODS: A WHO working group developed definitions for radiological pneumonia. Inter-observer variability in categorizing a set of 222 chest radiographic images was measured by comparing the readings made by 20 radiologists and clinicians with a reference reading. Intra-observer variability was measured by comparing the initial readings of a randomly chosen subset of 100 radiographs with repeat readings made 8-30 days later. FINDINGS: Of the 222 images, 208 were considered interpretable. The reference reading categorized 43% of these images as showing alveolar consolidation or pleural effusion (primary end-point pneumonia); the proportion thus categorized by each of the 20 readers ranged from 8% to 61%. Using the reference reading as the gold standard, 14 of the 20 readers had sensitivity and specificity of > 0.70 in identifying primary end-point pneumonia; 13 out of 20 readers had a kappa index of > 0.6 compared with the reference reading. For the 92 radiographs deemed to be interpretable among the 100 images used for intra-observer variability, 19 out of 20 readers had a kappa index of > 0.6. CONCLUSION: Using standardized definitions and training, it is possible to achieve agreement in identifying radiological pneumonia, thus facilitating the comparison of results of epidemiological studies that use radiological pneumonia as an outcome.