Access to trauma centers in the United States

Context  Previous studies have reported that the number and distribution of trauma centers are uneven across states, suggesting large differences in access to trauma center care. Objective  To estimate the proportion of US residents having access to trauma centers within 45 and 60 minutes. Design and Setting  Cross-sectional study using data from 2 national databases as part of the Trauma Resource Allocation Model for Ambulances and Hospitals (TRAMAH) project. Trauma centers, base helipads, and block group population were counted for all 50 states and the District of Columbia as of January 2005. Main Outcome Measures  Percentages of national, regional, and state populations having access to all 703 level I, II, and III trauma centers in the United States by either ground ambulance or helicopter within 45 and 60 minutes. Results  An estimated 69.2% and 84.1% of all US residents had access to a level I or II trauma center within 45 and 60 minutes, respectively. The 46.7 million Americans who had no access within an hour lived mostly in rural areas, whereas the 42.8 million Americans who had access to 20 or more level I or II trauma centers within an hour lived mostly in urban areas. Within 45 and 60 minutes, respectively, 26.7% and 27.7% of US residents had access to level I or II trauma centers by helicopter only and 1.9% and 3.1% of US residents had access to level I or II centers only from trauma centers or base helipads outside their home states. Conclusion  Selecting trauma centers based on geographic need, appropriately locating medical helicopter bases, and establishing formal agreements for sharing trauma care resources across states should be considered to improve access to trauma care in the United States.      

Bacteraemia following periodontal procedures

INTRODUCTION: Transient bacteraemias are frequently detected following dental manipulation. Infective endocarditis (IE) can arise in susceptible individuals and antibiotic prophylaxis is routinely performed for certain procedures considered to be "at risk" of IE. Evidence is emerging that periodontal disease may be a significant risk factor for the development of certain systemic diseases such as cardiovascular disease. These systemic conditions could be initiated or detrimentally influenced by the repeated entry of bacteria into the bloodstream. MATERIALS AND METHODS: The present study comprised a single blind parallel study of 2 weeks duration. A baseline blood sample was obtained from 30 volunteers with untreated periodontal disease following which a periodontal probing depth chart was collected. A further blood sample was taken following this procedure, and each subject was recalled 2 weeks later. A blood sample was collected, the subject carried out toothbrushing and a further blood sample taken. Full-mouth ultrasonic scaling was then performed and a final blood sample taken. Blood samples were analysed for bacteraemia using conventional microbiological culture and polymerase chain reaction (PCR) using universal bacterial primers that target the 16S ribosomal RNA gene of the vast majority of bacteria. RESULTS: Using culture methods, the incidence of bacteraemias was as follows: following ultrasonic scaling (13%), periodontal probing (20%) and toothbrushing (3%). PCR analysis revealed bacteraemia incidences following ultrasonic scaling, periodontal probing and toothbrushing of 23%, 16% and 13%, respectively. CONCLUSION: These findings suggest that detectable dental bacteraemias induced by periodontal procedures are at a lower level than previously reported.     

Video analysis of endoscopic cutting task performed by one versus two operators

Background In the performance of complex laparoscopic tasks, one question is whether the task should be distributed between two operators or accomplished bimanually by one operator. The authors hypothesized that superior task performance results when two operators work collaboratively in a dyad team as opposed to one operator performing the task bimanually. Furthermore, in a visually misaligned condition, the performance of a team will be more robust than that of a single operator working alone. Methods The suture-cutting task was performed by 24 right-handed subjects in a mock surgical setup using a laparoscopic grasper and a pair of laparoscopic scissors. The cutting task was performed by 8 subjects bimanually (using both limbs) and 16 paired subjects unimanually (using their preferred limbs). The image of the work plane was displayed either vertically or superimposed over the work plane. In half of the conditions, the camera was rotated 45°, causing misalignment between the actual and displayed work planes. Movements were videotaped. Important movement events were identified and used to subdivide the task into subtasks. Durations of the subtasks and attempts for grasping and cutting were analyzed using a mixed-design multivariate analysis of variance (MANOVA). Results For a number of subtasks, the dyad group showed shorter durations than the bimanual group. The 45° rotation of the camera degraded both bimanual and dyad performance, resulting in prolonged movement times for all subtasks. The learning process was facilitated by the superimposed display in that grasper and scissor reaching times improved over trials, as compared with the vertical display. Conclusion The results indicate the superior role of team collaboration, as compared with the single operator, in a complex remote manipulation such as a laparoscopic cutting task. This enhanced task performance is achieved because of the larger capacity for information processing. These results may have some relevance for optimizing performance of endoscopic surgery.     

Atlantoaxial instability associated with an orthotopic os odontoideum: a multimodality imaging assessment

Radiography, computed tomography (CT), and magnetic resonance imaging exams of the cervical spine were performed in a 29-year-old man who was ultimately diagnosed with an orthotopic os odontoideum during admission for injuries sustained in a motor vehicle collision. Initial radiography suggested either os odontoideum or an acute fracture of the dens. Further imaging with CT and flexion and extension radiographs confirmed os odontoideum and excluded a dens fracture. Although rare, os odontoideum is an important cervical spine anomaly to consider and to distinguish from an acute fracture of the dens.     

Identification of pectenotoxin-11 as 34S-hydroxypectenotoxin-2, a new pectenotoxin analogue in the toxic dinoflagellate Dinophysis acuta from New Zealand

A new pectenotoxin, which has been named pectenotoxin-11 (PTX11), was isolated from the dinoflagellate Dinophysis acuta collected from the west coast of New Zealand. The structure of PTX11 was determined as 34S-hydroxypectenotoxin-2 by tandem mass spectrometry and UV and NMR spectroscopy. PTX11 appears to be only the third pectenotoxin identified as a natural biosynthetic product from algae after pectenotoxin-2 and pectenotoxin-12. The LD50 of PTX11 determined by mouse intraperitoneal injection was 244 microg/kg. The LD(min) of PTX11 in these experiments was 250 microg/kg. No signs of toxicity were recorded in mice following an oral dose of PTX11 at 5000 microg/kg. No diarrhea was observed in any of the animals administered with the test substance by either route of administration. Unlike pectenotoxin-2 (PTX2), PTX11 was not readily hydrolyzed to its corresponding seco acid by enzymes from homogenized green-lipped mussel (Perna canaliculus) hepatopancreas.     

Three-dimensional high-frequency ultrasound imaging for longitudinal evaluation of liver metastases in preclinical models

Liver metastasis is a clinically significant contributor to the mortality associated with melanoma, colon, and breast cancer. Preclinical mouse models are essential to the study of liver metastasis, yet their utility has been limited by the inability to study this dynamic process in a noninvasive and longitudinal manner. This study shows that three-dimensional high-frequency ultrasound can be used to noninvasively track the growth of liver metastases and evaluate potential chemotherapeutics in experimental liver metastasis models. Liver metastases produced by mesenteric vein injection of B16F1 (murine melanoma), PAP2 (murine H-ras-transformed fibroblast), HT-29 (human colon carcinoma), and MDA-MB-435/HAL (human breast carcinoma) cells were identified and tracked longitudinally. Tumor size and location were verified by histologic evaluation. Tumor volumes were calculated from the three-dimensional volumetric data, with individual liver metastases showing exponential growth. The importance of volumetric imaging to reduce uncertainty in tumor volume measurement was shown by comparing three-dimensional segmented volumes with volumes estimated from diameter measurements and the assumption of an ellipsoid shape. The utility of high-frequency ultrasound imaging in the evaluation of therapeutic interventions was established with a doxorubicin treatment trial. These results show that three-dimensional high-frequency ultrasound imaging may be particularly well suited for the quantitative assessment of metastatic progression and the evaluation of chemotherapeutics in preclinical liver metastasis models.     

Comparing step-and-shoot IMRT with dynamic helical tomotherapy IMRT plans for head-and-neck cancer

PURPOSE: The goal of this planning study was to compare step-and-shoot intensity-modulated radiotherapy (IMRT) plans with helical dynamic IMRT plans for oropharynx patients on the basis of dose distribution. METHODS AND MATERIALS: Five patients with oropharynx cancer had been previously treated by step-and-shoot IMRT at the University Medical Centre Utrecht, The Netherlands, applying five fields and approximately 60-90 segments. Inverse planning was carried out using Plato, version 2.6.2. For each patient, an inverse IMRT plan was also made using Tomotherapy Hi-Art System, version 2.0, and using the same targets and optimization goals. Statistical analysis was performed by a paired t test. RESULTS: All tomotherapy plans compared favorably with the step-and-shoot plans regarding sparing of the organs at risk and keeping an equivalent target dose homogeneity. Tomotherapy plans in particular realized sharper dose gradients compared with the step-and-shoot plans. The mean dose to all parotid glands (n = 10) decreased on average 6.5 Gy (range, -4 to 14; p = 0.002). The theoretical reduction in normal tissue complication probabilities in favor of the tomotherapy plans depended on the parotid normal tissue complication probability model used (range, -3% to 32%). CONCLUSION: Helical tomotherapy IMRT plans realized sharper dose gradients compared with the clinically applied step-and shoot plans. They are expected to be able to reduce the parotid normal tissue complication probability further, keeping a similar target dose homogeneity.     

Oral misoprostol for cervical priming in non-pregnant women

Endometrial biopsy and hysteroscopy are important investigations in women presenting with abnormal vaginal bleeding. Endometrial biopsy is often performed as an outpatient procedure by endometrial aspiration. Difficulty in entering the internal cervical os may be encountered, especially in nulliparous women. The same problem may occur during hysteroscopy or dilatation and curettage. It is well known that use of a cervical priming agent is effective in reducing complications during cervical dilatation in pregnant women. However, its use in non-pregnant women is not well established. We compared oral misoprostol versus placebo for a cervical priming effect in non-pregnant women prior to hysteroscopy. The cumulative force required for cervical dilatation was significantly lower whereas the baseline cervical dilatation was significantly greater in the misoprostol group. We conclude that oral misoprostol is effective for pre-operative cervical dilatation in non- pregnant women.      

Cytogenetic evidence that the malignant event in multiple myeloma occurs in a precursor lymphocyte

Multiple myeloma is traditionally thought of as a disease of plasma cells. Evidence from studies using antiodiotype antibodies, however, suggests that malignant events may take place in a precursor lymphocyte perhaps as early as the pre-B cell. In this study, we present cytogenetic evidence to support the latter view. Peripheral blood was obtained from a patient with plasma cell leukemia and light chain disease. Karyotypic analysis, using Giemsa banding techniques, showed an abnormal karyotype: 44,XY,-6,-8,-13,-16,-22,+mar1,+ mar2,+mar3,del(1)(p22,p32),11p+,13q+,14q+. A suspension culture was established and a plasma cell line was grown. It was characterized by transmission electron microscopy as having an eccentric nucleus, abundant cytoplasm, and extensive endoplasmic reticulum. A subculture of this line was subsequently grown that was characterized by transmission electron microscopy as a lymphoid cell with diminished quantity of cytoplasm without extensive endoplasmic reticulum. Karyotypic analysis of the smaller cell demonstrated a modal number of 88 chromosomes and was a tetraploid derivative of the first. Our study provides cytogenetic evidence that cells with a lymphocytic phenotype show karyotypic abnormalities seen in the malignant plasma cell of the same patient, and thus, can be considered as evidence favoring the initiating cell of plasma cell myeloma as being an early B lymphocyte.     

Structure and composition of silicon-stabilized tricalcium phosphate

Silicon stabilized tricalcium phosphate [Si-TCP] is formed within the calcium hydroxyapatite (HA)-tricalcium phosphate (TCP) system when a stoichiometric precipitate of hydroxyapatite is fired at 1,000 degrees in the presence of SiO(2). This paper proposes a composition range and crystallographic structure for Si-TCP. Reitveld XRD powder diffraction, transmission electron microscopy, infrared and proton nuclear magnetic resonance measurements show that crystalline Si-TCP is associated with the displacement of OH from an initial hydroxyapatite structure. The resulting calcium phosphate is modified by the incorporation of silicon into its structure with excess silica contributing to an amorphous component. Si-TCP has a monoclinic structure with a space group P2(1)/a akin to alpha-TCP with estimated lattice constants of a=12.863+/-0.004 A, b=9.119 +/-0.003 A, c=15.232+/-0.004 A, beta=126.3+/-0.1 degrees. It is proposed that Si(4+) substitutes for P(5+)in the TCP lattice with the average chemical composition of Si-TCP set primarily by the mechanisms available for charge compensation. While the formation of OH vacancies in HA initiates the transformation to Si-TCP, two mechanisms of charge compensation in the Si-TCP structure are plausible. If O(2-) vacancies provide charge compensation, the composition of Si-TCP is Ca(3)(P(0.9)Si(0.1)O(3.95))(2) derived for the addition of 0.33 mol SiO(2):mol HA. If excess Ca(2+) compensates, the composition is Ca(3.08)(P(0.92)Si(0.08)O(4))(2) derived for the addition of 0.25 mol SiO(2):mol HA. The reaction occurs most effectively when SiO(2) is added as a colloidal suspension rather than by the in-situ thermal decomposition of a silicon metallorganic compound. The material is a bioceramic of major biological interest because of its osteoconductivity and unique influence on skeletal tissue repair and remodeling.