Calculation of beta-ray dose distributions from ophthalmic applicators and comparison with measurements in a model eye

Dose distributions throughout the eye, from three types of beta-ray ophthalmic applicators, were calculated using the EGS4, ACCEPT 3.0, and other Monte Carlo codes. The applicators were those for which doses were measured in a recent international intercomparison [Med. Phys. 28, 1373 (2001)], planar applicators of 106Ru-106Rh and 90Sr-90Y and a concave 106Ru-106Rh applicator. The main purpose was to compare the results of the various codes with average experimental values. For the planar applicators, calculated and measured doses on the source axis agreed within the experimental errors (<10%) to a depth of 7 mm for 106Ru-106Rh and 5 mm for 90Sr-90Y. At greater distances the measured values are larger than those calculated. For the concave 106Ru-106Rh applicator, there was poor agreement among available calculations and only those calculated by ACCEPT 3.0 agreed with measured values. In the past, attempts have been made to derive such dose distributions simply, by integrating the appropriate point-source dose function over the source. Here, we investigated the accuracy of this procedure for encapsulated sources, by comparing such results with values calculated by Monte Carlo. An attempt was made to allow for the effects of the silver source window but no corrections were made for scattering from the source backing. In these circumstances, at 6 mm depth, the difference in the results of the two calculations was 14%-18% for a planar 106Ru-l06Rh applicator and up to 30% for the concave applicator. It becomes worse at greater depths. These errors are probably caused mainly by differences between the spectrum of beta particles transmitted by the silver window and those transmitted by a thickness of water having the same attenuation properties.     

Rapid identification of Candida dubliniensis using a species-specific molecular beacon

Candida dubliniensis is an opportunistic fungal pathogen that has been linked to oral candidiasis in AIDS patients, although it has recently been isolated from other body sites. DNA sequence analysis of the internal transcribed spacer 2 (ITS2) region of rRNA genes from reference Candida strains was used to develop molecular beacon probes for rapid, high-fidelity identification of C. dubliniensis as well as C. albicans. Molecular beacons are small nucleic acid hairpin probes that brightly fluoresce when they are bound to their targets and have a significant advantage over conventional nucleic acid probes because they exhibit a higher degree of specificity with better signal-to-noise ratios. When applied to an unknown collection of 23 strains that largely contained C. albicans and a smaller amount of C. dubliniensis, the species-specific probes were 100% accurate in identifying both species following PCR amplification of the ITS2 region. The results obtained with the molecular beacons were independently verified by random amplified polymorphic DNA analysis-based genotyping and by restriction enzyme analysis with enzymes BsmAI and NspBII, which cleave recognition sequences within the ITS2 regions of C. dubliniensis and C. albicans, respectively. Molecular beacons are promising new probes for the rapid detection of Candida species.     

The architecture of variant surface glycoprotein gene expression sites in Trypanosoma brucei

Trypanosoma brucei evades the immune system by switching between Variant Surface Glycoprotein (VSG) genes. The active VSG gene is transcribed in one of approximately 20 telomeric expression sites (ESs). It has been postulated that ES polymorphism plays a role in host adaptation. To gain more insight into ES architecture, we have determined the complete sequence of Bacterial Artificial Chromosomes (BACs) containing DNA from three ESs and their flanking regions. There was variation in the order and number of ES-associated genes (ESAGs). ESAGs 6 and 7, encoding transferrin receptor subunits, are the only ESAGs with functional copies in every ES that has been sequenced until now. A BAC clone containing the VO2 ES sequences comprised approximately half of a 330 kb 'intermediate' chromosome. The extensive similarity between this intermediate chromosome and the left telomere of T. brucei 927 chromosome I, suggests that this previously uncharacterised intermediate size class of chromosomes could have arisen from breakage of megabase chromosomes. Unexpected conservation of sequences, including pseudogenes, indicates that the multiple ESs could have arisen through a relatively recent amplification of a single ES.     

Haemodynamic Adjustments to Mental Stress in Normotensives and Subjects with Mildly Elevated Blood Pressure

Cardiac output, heart rate, stroke volume, pre-ejection period, total peripheral resistance, systolic and diastolic blood pressure, and oxygen consumption were monitored or derived in young men with mildly elevated casual blood pressures and unambiguously normotensive control subjects before, during, and after exposure to a mental arithmetic stress. Measurements were also taken while subjects underwent graded dynamic exercise. This permitted cardiac output-oxygen consumption regression equations to be calculated and, as a consequence, cardiac output during mental stress to be represented as additional cardiac output. Systolic and diastolic blood pressure were higher during all phases of the study in the mildly elevated blood pressure group. An overall groups effect during the mental stress phase of the experiment was observed for cardiac output and pre-ejection period, and the effect for stroke volume was close to significance. Significant Groups X Periods interactions were found for cardiac output and additional cardiac output, and the heart rate effect was nearly significant. Post-hoc comparisons here indicated that, in the main, group differences in these cardiac variables were more evident during the mental arithmetic stress than during the pre- and post-task baseline periods. Total peripheral resistance did not differ reliably between groups and the cardiac effects were specific to the mental stress phase of the study.     

The effect of carbonic anhydrase inhibition on bicarbonate reabsorption

Summary Renal reabsorption of bicarbonate was studied in Merino ewes during carbonic anhydrase inhibition. Bicarbonate reabsorption was directly proportional to plasma bicarbonate concentration. No tubular maximum for bicarbonate was demonstrated. Elevation of arterialPCO₂ or depression of arterial pH caused slight increases in bicarbonate reabsorption. The data suggest that bicarbonate is reabsorbed by 2 distinct processes. The quantitatively more significant process may involve ionic reabsorption of bicarbonate secondary to Na⁺ reabsorption and a relatively minor part of bicarbonate reabsorption may be secondary to H⁺ secretion.     

Amyloid in prostatic corpora amylacea.

AIM: To determine the presence and nature of amyloid in prostatic corpora amylacea using immunohistological studies. METHODS: Prostatic tissue from 18 transurethral and two open resection specimens was studied. Paraffin wax embedded tissue sections were stained with haematoxylin and eosin and the alkaline Congo red method with and without previous treatment with potassium permanganate. Sections were also stained with antibodies to amyloid A, beta 2 microglobulin, lambda and kappa light chains, prealbumin IgA, G, M, S100 protein, prostatic specific antigen, amyloid P component and CAM 5.2 (control and blocking studies were performed). RESULTS: The prostatic corpora amylacea universally showed the presence of amyloid. In all instances this contained beta 2 microglobulin. CONCLUSION: Prostatic corpora amylacea represents a localised amyloidosis of beta 2 microglobulin origin that is unrelated to chronic renal failure and haemodialysis.     

A de novo translocation t(3;17)(q26.3;q23.1) in a child with Cornelia de Lange syndrome.

A female infant with Cornelia de Lange syndrome and severe limb reduction defects is described. Chromosome analysis showed a de novo translocation with breakpoints at 3q26.3 and 17q23.1. This is the first reported case of a de novo translocation associated with this syndrome.     

Self-reported comfort in athletic training of gender-specific and non-gender-specific injuries and issues

Context: To assist athletes in maintaining optimal health, athletic trainers must work with athletes of both sexes.Objective: To examine athletic trainers'' comfort levels in providing care for gender-specific and non-gender-specific injuries and issues.Design: We mailed 235 Gender Comfort in Athletic Training Questionnaires to program directors, who were asked to distribute and collect them.Setting: We randomly selected 21 athletic training education program directors and invited them by e-mail to participate in the study. Fourteen program directors representing the 10 National Athletic Trainers'' Association districts agreed to participate.Patients or Other Participants: A total of 192 participants returned completed questionnaires, for a response rate of 82% (103 women, 89 men; 101 senior athletic training students, 91 certified athletic trainers).Main Outcome Measure(s): The questionnaire consisted of 17 injuries and issues common to both female and male athlete scenarios. Three gender-specific items were added to each scenario. Responses were scored on a 5-point scale anchored by 1 (very uncomfortable) and 5 (very comfortable). Participants were asked to indicate the reason for any degree of discomfort. Internal consistency, determined by the Cronbach alpha, was .92 for the female athlete scenario and .93 for the male athlete scenario.Results: We found significant differences between women and men certified athletic trainers for the female and male athlete scenarios. Overall, women were more comfortable caring for female injuries and issues, whereas men were more comfortable caring for male injuries and issues. Certified athletic trainers reported more comfort overall than athletic training students. The most common underlying reason reported for discomfort in caring for female and male injuries and issues was experience level.Conclusions: Athletic training education programs should provide early and more deliberate experiences with injuries and issues of a more intimate nature, including those that are gender specific and non-gender specific. These experiences may increase athletic trainers'' level of comfort in providing care to athletes of the opposite sex.