Risk factors associated with the development of post-traumatic retained hemothorax.

OBJECTIVE: To identify risk factors associated with the development of post-traumatic retained hemothorax in chest trauma patients admitted to Hospital San Vicente de Paul (HUSVP). METHODS: This study was a prospective cohort study that included patients with a diagnosis of chest trauma who required a tube thoracostomy as a therapeutic intervention. The measured outcome was retained hemothorax, defined as the presence of blood in the pleural cavity that could not be drained through the initial tube thoracostomy and appeared radio-opaque or hypodense on X-rays or CT scan. The postoperative follow-up period was 30 days. RESULTS: Six hundred thirty-three thoracostomies were performed over a 28-month period for chest trauma; the incidence of post-traumatic retained hemothorax was 16.7%, and additional complications were seen in 10% of cases. The risk of retained hemothorax was associated with: initial blood drainage (median, 400 ml; p < 0.001), the number of tubes placed (two or more; OR = 5.35, CI 95%: 3.98-7.20), the duration of the tube thoracostomy (median, 5 days; p = 0.01), and the need for mechanical ventilation (RR = 2.5, CI 95%: 1.66-3.75). CONCLUSIONS: The risk of post-traumatic retained hemothorax was associated with four factors. The probability of the outcome could be modified by careful monitoring, management protocols, suction through the tube thoracostomy, and maybe an early intervention, such as thoracoscopy.

[Lasers in dentistry 7. The use of 3D imaging in dentistry]. / Lasers in de tandheelkunde 7. Het gebruik van driedimensionale beelden in de tandheelkunde.

Optical surface scanning accurately records the 3D nature of the face non-invasively and quantitatively. Programmes to analyse the data now enable the clinician to compare the changes in the face as the result of growth or of treatment and also to average groups of patients to provide an assessment of treatment. An average face has been obtained from groups of patients each year from 5 to 18 years. Growth of an individual can be compared with the norm for that age to determine which areas of the face show abnormal growth. Prediction of facial form for forensic and surgical purposes is possible. Programmes have been developed that analyse shape and curvature of areas of the facial surface. Such an analysis can be used to determine the changes in the facial surface as the result of growth, treatment, or drug therapy and to study genetic effects.

The Drosophila U1 and U6 gene proximal sequence elements act as important determinants of the RNA polymerase specificity of small nuclear RNA gene promoters in vitro and in vivo.

Transcription of genes coding for metazoan spliceosomal snRNAs by RNA polymerase II (U1, U2, U4, U5) or RNA polymerase III (U6) is dependent upon a unique, positionally conserved regulatory element referred to as the proximal sequence element (PSE). Previous studies in the organism Drosophila melanogaster indicated that as few as three nucleotide differences in the sequences of the U1 and U6 PSEs can play a decisive role in recruiting the different RNA polymerases to transcribe the U1 and U6 snRNA genes in vitro. Those studies utilized constructs that contained only the minimal promoter elements of the U1 and U6 genes in an artificial context. To overcome the limitations of those earlier studies, we have now performed experiments that demonstrate that the Drosophila U1 and U6 PSEs have functionally distinct properties even in the environment of the natural U1 and U6 gene 5'-flanking DNAs. Moreover, assays in cells and in transgenic flies indicate that expression of genes from promoters that contain the "incorrect" PSE is suppressed in vivo. The Drosophila U6 PSE is incapable of recruiting RNA polymerase II to initiate transcription from the U1 promoter region, and the U1 PSE is unable to recruit RNA polymerase III to transcribe the U6 gene.

Revision total knee arthroplasty with a cemented posterior-stabilized or constrained condylar prosthesis: a minimum 3-year and average 5-year follow-up study.

The results of 57 revision total knee arthroplasties performed for aseptic failure between 1984 and 1992 with a cemented posterior-stabilized or constrained condylar prosthesis were reviewed at follow-up examinations at a minimum of 36 and an average of 62 months (range, 36-120 months). The reason for revision was aseptic loosening of 1 or both components in 32 knees (56%), instability in 16 knees (28%), polyethylene wear and osteolysis in 4 knees (7%), supracondylar femur fracture in 2 knees (4%), and a failed allograft, pain, and arthrofibrosis in 1 knee each (5% total). The average age of the patients at the time of the revision was 74 years (range, 38-90), and the original diagnosis for the majority of patients was osteoarthritis (74%). All of the revision prostheses were cemented posterior stabilized or constrained condylar-type implants. Bone deficiencies were grafted with cancellous allograft in contained defects and cortical allograft in noncontained defects. Five knees were reconstructed with allograft-prosthesis composites. The average modified Hospital for Special Surgery knee score improved from 49 to 82 (100 points possible) at final follow-up evaluation (P < 0.001). Seventy-nine percent of knees were graded as good or excellent. Kaplan-Meier survivorship analysis predicted 94%+/-6.2% survival at 40 months and 75%+/-25% at 99 months. There were 4 clinical failures, 3 of which were related to residual instability in patients with a posterior-stabilized prosthesis. Complications (3 knees) were exclusively related to the extensor mechanism. Radiographically, overall knee alignment improved from 0.3 degrees varus to 3.0 degrees valgus. Fifty-six percent of tibial components were placed in slight varus alignment. Radiolucent lines occurred in 33% of knees, but there were no complete or progressive radiolucencies. Radiolucent lines were more prevalent adjacent to press-fit intramedullary femoral stems compared with cemented stems (P < .02), but the difference did not correlate with clinical or radiographic failure. The median bone defect score, as proposed by the Knee Society Committee on Bone Defects, was significantly greater in knees that were revisions of a failed cemented total knee arthroplasty compared with revision of a failed cementless total knee arthroplasty (P = .02) but was not correlated with clinical or radiographic outcome (P > .05).

Maintenance of the patency of indwelling central venous catheters: is heparin necessary?

The use of indwelling central venous catheters for the ambulatory management of children with cancer has been well described. There remains uncertainty as to the best method for maintaining the patency of these catheters. The standard approach at our institution is to flush the catheter twice daily with a solution containing heparin. This is both costly and inconvenient for most families. We describe a randomized cross-over study designed to compare the standard approach to a less intense program using an isotonic saline flush once a week. Evaluation continued for approximately 1,515 days in each study arm. The catheters were monitored for blockage, clot formation, and infection. One catheter blocked in a patient receiving the experimental method of care. Two episodes of thrombus formation were demonstrated at the end of the study (one in each of the study arms). The incidence of infection, while in keeping with our overall experience, was higher in the experimental arm. This led to a subsequent study, reported separately in this symposium. The results indicate that there is no significant difference, in the incidence of blocked catheters or other complications, between the two forms of care.

Occurrence and developmental pattern of neuromedin U-immunoreactive nerves in the gastrointestinal tract and brain of the rat.

Neuromedin U is a newly described regulatory peptide, found by radioimmunoassay in significant concentrations in both the brain and gut of the rat. The aim of the present study was to localize this peptide immunoreactivity to discrete structures of the gut and brain and to map its distribution using immunocytochemistry. In the gut, neuromedin U was confined to nerve fibres mainly in the myenteric and submucous plexuses and the mucosa of all areas except stomach. Immunoreactive ganglion cells were seen in both ganglionated plexuses and their number did not increase following colchicine administration. This observation and the finding that the population of neuromedin U-immunoreactive nerves in the ileum was not affected by complete extrinsic denervation indicated that the nerves are mostly intrinsic in origin. Colocalization studies revealed neuromedin U and calcitonin gene-related peptide were present in the same myenteric and submucosal ganglion cells. Transection experiments showed that, like calcitonin gene-related peptide-immunoreactive nerves, fibres containing neuromedin U project for very short distances in both an oral and anal direction. At the electron microscopic level, neuromedin U immunoreactivity, demonstrated using the immunogold technique, was localized to large granular vesicles. In the central nervous system, neuromedin U immunoreactivity was localized to fibres which were widespread throughout the brain, except in the cerebellum. The presence of neuromedin U-immunoreactive cell bodies was restricted to the rostrocaudal part of the arcuate nucleus. Colocalization studies showed that a proportion of the neuromedin U-immunoreactive cell bodies in the arcuate nucleus also contained pro-opiomelanocortin. Neuromedin U-immunoreactive fibres were first detected in the rat intestinal mucosa at day 1 after birth. In the brain, the arcuate nucleus showed neuromedin U-immunoreactive neuronal cell bodies at E16 but not at E14. In conclusion, neuromedin U is a new member of the group of molecules known as brain-gut peptides.

Endocarditis caused by Neisseria mucosa in a patient with a prosthetic heart valve.

A forty year old man was admitted with suspected subacute bacterial endocarditis. Neisseria mucosa was isolated in pure culture. Initial antibiotic therapy included penicillin and gentamicin. After onset of allergic symptoms, penicillin was discontinued and vancomycin therapy instituted. Gentamicin therapy was discontinued after the serum creatinine began to rise. Minimum inhibitory concentration indicated that N mucosa was resistant to vancomycin. After allergy testing proved negative, intravenous penicillin therapy was reinstituted and continued until discharge, at which time the patient was to continue on oral penicillin for six months.