PubMed Health⌕ Search

Biomedical subjects

Robert A Jones

Publications and source records attributed to Robert A Jones.

10 recordsLinked to original sources
PubMed2006

Pilot study to evaluate the accuracy of ultrasonography in confirming endotracheal tube placement.

STUDY OBJECTIVE: Visualization of the vocal cords and end-tidal capnography are the usual standards in confirming endotracheal tube placement. Vocal cord visualization is, however, not always possible, and capnography is not 100% reliable and requires ventilation of the lungs to confirm placement. The goal of this study is to determine the accuracy of ultrasonography for detecting endotracheal tube placement into the trachea and esophagus in real time. METHODS: This was a prospective, randomized, controlled study. Eligible patients were adults undergoing elective surgery requiring intubation. Exclusion criteria were a history of difficult intubation, abnormal airway anatomy, aspiration risk factors, and esophageal disease. Thirty-three patients were enrolled. After induction of anesthesia and neuromuscular blockade, the anesthesiologist placed the endotracheal tube in the trachea and esophagus in random order with direct laryngoscopy. During the intubations, a high-frequency, linear transducer was placed transversely on the neck at the suprasternal notch. Two emergency physicians, blinded to the order and performance of the intubations, independently recorded the location of the endotracheal tube according to the real-time ultrasonographic image. A 2-by-2 table was used to calculate sensitivity and specificity of the emergency physicians' ability to detect placement of the endotracheal tube. RESULTS: For each physician, the sensitivity for identifying the first intubation as tracheal was 100% (95% confidence interval [CI] 77% to 100%) with a specificity of 100% (95% CI 82% to 100%). One endotracheal tube was unintentionally placed twice in the esophagus, but both tube placements were identified as esophageal by the emergency physicians. CONCLUSION: In this pilot study, 2 emergency physicians experienced in ultrasonography accurately detected placement of endotracheal tubes during intubation with ultrasonography in select patients in the controlled environment of the operating room. Future studies should examine the use of ultrasonography to visualize endotracheal tube placement in real time by emergency physicians with less ultrasonographic training; use of the technique in the emergency department on a wider range of patients, including patients with difficult airways; and assessment of the utility of ultrasonography in confirmation of endotracheal tube position in already intubated patients.

Adult↗
PubMed2005

Devices for gradient static magnetic field exposure.

We describe devices designed for magnetic field exposures in which field amplitude and gradients are controlled simultaneously. Dosimetry based on field continuation of high resolution magnetic field scans and numerical models is compared with validation measurements. The dosimetry variables we consider are based on the assumption that the biological or chemical system under study has field transducers that are spatially isotropic, so that absolute field amplitude and two gradient components fully describe local exposure.

Cell Culture Techniques↗
PubMed2005

'How many female scientists do you know?'.

The stereotypical scientist wears a lab-coat, is often eccentric and is usually male. Images of female scientists in popular culture remain rare. Some of the first portrayals of women in science occurred in a handful of British films made during the 1950s and 1960s. These films reflected the difficulties experienced by women in science at the time, but they might also explain why representations of female scientists in film continue to downplay their role as scientists and emphasize their identity as women.

Female↗
PubMed2004

Whole genome analysis reveals a high incidence of non-optimal codons in secretory signal sequences of Escherichia coli.

Translational pausing may occur due to a number of mechanisms, including the presence of non-optimal codons, and it is thought to play a role in the folding of specific polypeptide domains during translation and in the facilitation of signal peptide recognition during sec-dependent protein targeting. In this whole genome analysis of Escherichia coli we have found that non-optimal codons in the signal peptide-encoding sequences of secretory genes are overrepresented relative to the "mature" portions of these genes; this is in addition to their overrepresentation in the 5'-regions of genes encoding non-secretory proteins. We also find increased non-optimal codon usage at the 3' ends of most E. coli genes, in both non-secretory and secretory sequences. Whereas presumptive translational pausing at the 5' and 3' ends of E. coli messenger RNAs may clearly have a general role in translation, we suggest that it also has a specific role in sec-dependent protein export, possibly in facilitating signal peptide recognition. This finding may have important implications for our understanding of how the majority of non-cytoplasmic proteins are targeted, a process that is essential to all biological cells.

Codon↗
PubMed2004

Sonographic assessment of the epiglottis.

OBJECTIVES: The ideal diagnostic test for the diagnosis of epiglottitis would be simple, rapid, noninvasive, and highly accurate, performed at the bedside, and would not use ionizing radiation. The purpose of this study was to assess the utility of ultrasound to image the epiglottis and to determine the range of normal epiglottis diameter for men and women. METHODS: This was a prospective study of a convenience sample of 100 subjects between the ages of 18 and 50 years who had no known acute or chronic laryngeal diseases or surgeries. The anterior neck of each subject was scanned in both the long and short axis with a 5-10 MHz linear transducer. Sonographically, the epiglottis appeared as a curvilinear, hypoechoic structure with an echogenic pre-epiglottic space. The sonographic appearance of the epiglottis and the pre-epiglottic space were recorded and anteroposterior measurements of the epiglottis just distal to the hyoid bone were made. Comparisons between men and women were performed with use of a Student's t-test. Pearson's correlation analysis was performed to evaluate the relationship between subject height and epiglottic size. RESULTS: The epiglottis was visualized in all 100 subjects including 62 women and 38 men. The average patient age was 35.2 +/- 8.1 years. The epiglottic thickness was 2.39 +/- 0.15 mm. This was greater in men (2.49 +/- 0.13 mm) than in women (2.34 +/- 0.13 mm) (p < 0.001). There was moderate correlation between height and epiglottic thickness (R = 0.48). However, when this was analyzed separately for men and women, there was no significant correlation between epiglottic thickness and height. CONCLUSIONS: Bedside ultrasonography is easy to perform and can accurately evaluate the epiglottis. Further analysis should include patients with known epiglottic disease to assess the utility of this technique to detect pathologic enlargement.

Adolescent↗
PubMedDate not supplied

Breast cancer incidence in postmenopausal women using testosterone in addition to usual hormone therapy.

OBJECTIVE: There is now convincing evidence that usual hormone therapy for ovarian failure increases the risk for breast cancer. We have previously shown that ovarian androgens normally protect mammary epithelial cells from excessive estrogenic stimulation, and therefore we hypothesized that the addition of testosterone to usual hormone therapy might protect women from breast cancer. DESIGN: This was a retrospective, observational study that followed 508 postmenopausal women receiving testosterone in addition to usual hormone therapy in South Australia. Breast cancer status was ascertained by mammography at the initiation of testosterone treatment and biannually thereafter. The average age at the start of follow-up was 56.4 years, and the mean duration of follow-up was 5.8 years. Breast cancer incidence in this group was compared with that of untreated women and women using usual hormone therapy reported in the medical literature and to age-specific local population rates. RESULTS: There were seven cases of invasive breast cancer in this population of testosterone users, for an incidence of 238 per 100,000 woman-years. The rate for estrogen/progestin and testosterone users was 293 per 100,000 woman-years--substantially less than women receiving estrogen/pro-gestin in the Women's Health Initiative study (380 per 100,000 woman-years) or in the "Million Women" Study (521 per 100,000 woman-years). The breast cancer rate in our testosterone users was closest to that reported for hormone therapy never-users in the latter study (283 per 100,000 woman-years), and their age-standardized rate was the same as for the general population in South Australia. CONCLUSIONS: These observations suggest that the addition of testosterone to conventional hormone therapy for postmenopausal women does not increase and may indeed reduce the hormone therapy-associated breast cancer risk-thereby returning the incidence to the normal rates observed in the general, untreated population.

Adult↗