Clinical, molecular, and drug resistance epidemiology of HIV in Jordan, 2019-2021: A national study.

BACKGROUND: Limited epidemiologic studies have been conducted in Jordan describing the HIV epidemic. This study aimed to address this gap to inform HIV prevention and control. METHODS: A nationally-representative cross-sectional study was conducted among adults living with HIV in Jordan. Laboratory testing included HIV viral load and next-generation-sequencing-based clinical genotype. Log-binomial regression estimated risk ratios (RRs) and 95% confidence intervals (CIs). RESULTS: Among 231 (70%) participants, most were male (184/80%), and from Jordan (217/94%). Among 188 treatment-experienced-participants (>6 months), 165 (88%) were virally suppressed. High-level resistance was most frequent against nucleoside reverse transcriptase inhibitor (13/81%), and integrase-strand transfer inhibitor (INSTI) (10/62%) drugs among viremic (≥1000 HIV copies/mL) treatment-experienced participants with drug-resistant mutations (DRMs, n = 16). Common HIV subtypes (n = 43) were B (6/14%), A1 (5/12%), and CRF01_AE (5/12%); additionally, novel recombinant forms were detected. In multivariate analysis, independently higher risk for late diagnosis (n = 49) was observed with diagnosis through blood donation (vs check-up: RR 2.20, 95%CI 1.16-4.17) and earlier time-period of diagnosis (1986-2014 vs 2015-2021: RR 2.87, 95%CI 1.46-5.62). CONCLUSIONS: Late diagnosis and INSTI resistance endanger national HIV prevention and treatment in Jordan-high-level resistance to INSTI suggests therapeutic drug monitoring is needed for treatment efficacy and conservation of treatment options.

Self-Adhesive and Antioxidant Poly(vinylpyrrolidone)/Alginate-Based Bilayer Films Loaded with Malva sylvestris Extracts as Potential Skin Dressings.

Malva sylvestris (MS) is a medicinal herb known worldwide for its beneficial effects due to the several active molecules present in its leaves and flowers. These compounds have shown antioxidant and anti-inflammatory properties and thus can be helpful in treatments of burns and chronic wounds, characterized mainly by high levels of free radicals and impairments of the inflammatory response. In this work, we propose bilayer films as wound dressings, based on poly(vinylpyrrolidone) (PVP) and sodium alginate loaded with M. sylvestris extracts from leaves and flowers and fabricated by combining solvent-casting and rod-coating methods. The top layer is produced in two different PVP/alginate ratios and loaded with the MS flowers' extract, while the bottom layer is composed of PVP and MS leaves' extract. The bilayers were characterized morphologically, chemically, and mechanically, while they showed superior self-adhesive properties on human skin compared to a commercial skin patch. The materials showed antioxidant activity, release of the bioactive compounds, and water uptake property. Moreover, the anthocyanin content of the flower extract provided the films with the ability to change color when immersed in buffers of different pH levels. In vitro tests using primary keratinocytes demonstrated the biocompatibility of the MS bilayer materials and their capacity to enhance the proliferation of the cells in a wound scratch model. Finally, the best performing MS bilayer sample with a PVP/alginate ratio of 70:30 was evaluated in mice models, showing suitable resorption properties and the capacity to reduce the level of inflammatory mediators in UVB-induced burns when applied to an open wound. These outcomes suggest that the fabricated bilayer films loaded with M. sylvestris extracts are promising formulations as active and multifunctional dressings for treating skin disorders.

A Survey of the Knowledge and Attitudes of Oncology Nurses toward Pain in United Arab Emirates Oncology Settings.

BACKGROUND: Effective cancer pain management mandates precise attitude, assessment, skills, and knowledge. Health professionals' knowledge and attitudes concerning cancer pain management have often been referred to as insufficient. AIMS: This study explored pain knowledge and attitudes of nurses working in oncology settings. SETTING AND PARTICIPANTS: Population 115 oncology nurses working at 2 hospitals in the United Arab Emirates. METHODS: A descriptive, correlational, cross-sectional design was used to examine nurse knowledge and attitudes about pain using the Nurses' Attitude and Knowledge Survey Regarding Pain (NKASRP) survey. NKASRP score differences were examined among nurses with varying demographics, levels of pain education and experience. RESULTS: The mean KASRP was 45%, significantly below the passing score of 80%. Pain management education was not found to have a significant impact on KASRP thus suggesting the need for more effective educational approaches to developing appropriate knowledge and attitudes towards pain among the nurses. No significant differences between sex, educational level, nursing and oncology experience, and nationality or religion were found. INTERPRETATION AND CONCLUSIONS: The study highlights the need for new initiatives targeting nurses working with cancer patients who are likely to experience significant pain. An ongoing need exists for more effective evidence-based educational programs in cancer pain management. Interactive teaching strategies such as on the job training, improvisational learning, and case studies should be tested for their influence on pain knowledge and attitudes and patient outcomes.

Dialysis disequilibrium syndrome: A preventable fatal acute complication.

Dialysis disequilibrium syndrome (DDS) is a neurological disorder with varying severity that is postulated to be associated with cerebral oedema. We described a case of DDS resulting in irreversible brain injury and death following acute haemodialysis. A 13-year-old male with no past medical history and weighing 30kg, presented to hospital with severe urosepsis complicated by acute kidney injury (Creatinine 1422mmol/L; Urea 74.2mmol/L, Potassium 6.3mmol/L, Sodium 137mmol/L) and severe metabolic acidosis (pH 6.99, HC03 1.7mmol/L). Chest radiograph was normal. Elective intubation was done for respiratory distress. Acute haemodialysis performed due to refractory metabolic acidosis. Following haemodialysis, he became hypotensive which required inotropes. His Riker's score was low with absence of brainstem reflexes after withholding sedation. CT Brain showed generalised cerebral oedema consistent with global hypoxic changes involving the brainstem. The symptoms of DDS are caused by water movement into the brain causing cerebral oedema. Two theories have been proposed: reverse osmotic shift induced by urea removal and a fall in cerebral intracellular pH. Prevention is the key to the management of DDS. It is important to identify high risk patients and haemodialysis with reduced dialysis efficacy and gradual urea reduction is recommended. Patients who are vulnerable to DDS should be monitored closely. Low efficiency haemodialysis is recommended. Acute peritoneal dialysis might be an alternative option, but further studies are needed.

Deletion Variants of Middle East Respiratory Syndrome Coronavirus from Humans, Jordan, 2015.

We characterized Middle East respiratory syndrome coronaviruses from a hospital outbreak in Jordan in 2015. The viruses from Jordan were highly similar to isolates from Riyadh, Saudi Arabia, except for deletions in open reading frames 4a and 3. Transmissibility and pathogenicity of this strain remains to be determined.

Impact of leadership styles adopted by head nurses on job satisfaction: a comparative study between governmental and private hospitals in Jordan.

BACKGROUND: Previous studies demonstrated that leadership styles are the basis of daily interactions between leaders and employees and facilitate and enhance work processes. AIM: This study aimed to explore how the leadership styles of nurse leaders affect job satisfaction among working nurses. METHODS: Quantitative, descriptive and comparative methods were used. Three main Ministry of Health hospitals in different areas of Jordan and three private hospitals in Amman were selected. RESULTS: Among the leadership styles measured by the Multi-factor Leadership Questionnaire 5X, transformational leadership had been used by head nurse managers in both settings more than transactional leadership and passive-avoidant leadership. The level of job satisfaction among nursing staff was higher in public hospitals than in private hospitals in this study. A positive relationship was found between the overall score for transformational leadership and job satisfaction (r = 0.374**). The overall transactional leadership score correlated positively with job satisfaction (r = 0.391**). Conversely, the overall correlation between passive-avoidant leadership and job satisfaction was negative (r = -0.240). CONCLUSION: The increased development of transformational leadership behaviours increases nurses' job satisfaction and thus contributes to an increased retention of nurses. IMPLICATIONS FOR NURSING MANAGEMENT: The ability of hospitals to address the leadership styles of head nurses and their impacts on job satisfaction will be strengthened.

Clinical implementation and error sensitivity of a 3D quality assurance protocol for prostate and thoracic IMRT.

This work aims at three goals: first, to define a set of statistical parameters and plan structures for a 3D pretreatment thoracic and prostate intensity-modulated radiation therapy (IMRT) quality assurance (QA) protocol; secondly, to test if the 3D QA protocol is able to detect certain clinical errors; and third, to compare the 3D QA method with QA performed with single ion chamber and 2D gamma test in detecting those errors. The 3D QA protocol measurements were performed on 13 prostate and 25 thoracic IMRT patients using IBA's COMPASS system. For each treatment planning structure included in the protocol, the following statistical parameters were evaluated: average absolute dose difference (AADD), percent structure volume with absolute dose difference greater than 6% (ADD6), and 3D gamma test. To test the 3D QA protocol error sensitivity, two prostate and two thoracic step-and-shoot IMRT patients were investigated. Errors introduced to each of the treatment plans included energy switched from 6 MV to 10 MV, multileaf collimator (MLC) leaf errors, linac jaws errors, monitor unit (MU) errors, MLC and gantry angle errors, and detector shift errors. QA was performed on each plan using a single ion chamber and 2D array of ion chambers for 2D and 3D QA. Based on the measurements performed, we established a uniform set of tolerance levels to determine if QA passes for each IMRT treatment plan structure: maximum allowed AADD is 6%; maximum 4% of any structure volume can be with ADD6 greater than 6%, and maximum 4% of any structure volume may fail 3D gamma test with test parameters 3%/3 mm DTA. Out of the three QA methods tested the single ion chamber performed the worst by detecting 4 out of 18 introduced errors, 2D QA detected 11 out of 18 errors, and 3D QA detected 14 out of 18 errors.

Effect of preoperative two-dimensional animation information on perioperative anxiety and knowledge retention in patients undergoing bowel surgery: a randomized pilot study.

AIM: The use of multimedia information provided preoperatively can potentially reduce anxiety in patients and improve the hospital experience. However, the use of two-dimensional (2D) animation (cartoon) to provide information to patients undergoing colorectal surgery has not been investigated. This study investigated the effect of preoperative 2D information on anxiety and knowledge retention in patients undergoing bowel surgery. METHOD: Patients were randomized to one of two groups; the video group watched a 13-min cartoon animation whereas the nonvideo group did not. Anxiety levels were measured at the preadmission clinic, postvideo, on the day of admission for surgery, within 24-h after surgery and before discharge using the Spielberger state-trait anxiety inventory and visual analogue scale. Both groups completed a knowledge retention questionnaire and the video group completed a feedback questionnaire about the animation. RESULTS: Thirty-one patients (16 video, 15 nonvideo) participated in the study. There was no significant difference in baseline anxiety score between two groups. An immediate reduction (P = 0.03) in anxiety score was observed in the video group after watching the video compared with baseline. There was a significant reduction in anxiety score in the video group at discharge compared with the nonvideo group (P = 0.03). There was no significant difference in knowledge retention between two groups. Eighty-eight per cent of patients who watched the video found it beneficial. CONCLUSION: 2D animation is an effective medium for delivering information to patients undergoing bowel surgery and can potentially reduce anxiety related to surgery and improve the hospital experience.

A method incorporating 4DCT data for evaluating the dosimetric effects of respiratory motion in single-arc IMAT.

This study introduces a method incorporating 4DCT data to determine the impact of respiratory motion in single-arc intensity-modulated arc therapy (IMAT). Simulation was done by re-warping the static dose distribution of all phases of a 4DCT image set with a 3D deformation map to reference CT images at end-inspiration and end-expiration. To calculate the dose received during respiration under IMAT, the control points were interpolated and re-distributed into separate IMAT plans corresponding to each respiratory phase. This study also investigated the role that plan complexity may play in the dosimetric impact of the respiratory motion in the delivery of IMAT. The dosimetric impact of organ motion was evaluated by analyzing the degradation of D(95,) D(50) and D(05) of the CTV and PTV. From the results shown for the patients in this study who had maximum organ motion displacement approximately 15 mm, the dosimetric impact is rather small. Therefore, our preliminary results suggest that respiratory motion of less than 1.5 cm may be ignored for both moderately and highly modulated IMAT, irrespective of the number of fractions. Specifically, highly modulated plans only increased the degradation of D(95) of the DVH curves for a single fraction by 2% in the CTV and 9% in the PTV compared to the expected value of the multi-fraction plan.

Multifactorial genetics of exencephaly in SELH/Bc mice.

BACKGROUND: The SELH/Bc mouse strain has 10-30% exencephaly and is an animal model for human neural tube closure defects. This study examined the number of causative genes, their dominance relationships, and linkage map positions. METHODS: The SELH/Bc strain (S) was crossed to the normal LM/Bc strain (L) and frequencies of exencephaly were observed in the F(1), BC(1), and F(2) generations. 102 F(2) males were individually testcrossed by SELH/Bc. The extremes, the 10 highest and 10 zero exencephaly-producing F(2) sires, were typed for 109 SSLP marker loci in a genome screen. Next, the resultant five provisional chromosomal regions were tested for linkage in 31 F(2) exencephalic embryos. Finally, 12 males, SS or LL for the Chr 13 region on an LM/Bc background, were testcrossed by SELH/Bc. RESULTS: The exencephaly frequencies in the F(1) (0.3%), BC(1) (4.4%), and F(2) (3.7%), and the distribution of F(2) males' testcross values (0-15.5%), indicated that the high risk of exencephaly in SELH/Bc is due to the cumulative effect of two or three loci. Linkage studies indicated the location of semidominant exencephaly-risk genes on Chr 13 near D13Mit13 (P < 0.001), Chr 5 near D5Mit168 (P < 0.025), and possibly Chr 11 near D11Mit10 (P < 0.07). The gene on Chr 13, Exen1, and the strong role of other loci were confirmed by the congenic males. CONCLUSIONS: The high risk of exencephaly in SELH/Bc mice is caused by the cumulative effect of two to three semidominant genes. Candidate genes include Msx2, Madh5, Ptch, and Irx1 (Chr 13) and Actb and Rac1 (Chr 5).

To move or not to move: measurements of prostate motion by urethrography using MRI.

PURPOSE: Urethrography is commonly used to aid in definition of the prostate apex during CT simulation for prostate cancer. If the position of the prostate were altered by the urethrogram itself, then systematic error could be introduced into the patient's treatment. Sagittal MRI scans were acquired immediately before and after a localization urethrogram to determine the extent of displacement. METHODS AND MATERIALS: Thirteen patients underwent sagittal T2-weighted fast spin echo MRI scans. Patients were scanned supine in an alpha cradle cast in the treatment position. The prostate was contoured by 3 different observers to determine the apex location on the central sagittal MRI section and the center of mass relative to an immobile bony landmark. Statistical multivariate analysis was performed to establish if there was a net displacement of the prostate (systematic error), and to determine the margin required to cover the random prostate position within a 95% confidence interval. RESULTS: There was no significant systematic motion of either the prostate nor its apex in either the anterior-posterior or superior-inferior directions. The average motion of the prostate center of mass was 0.04 +/- 0.40 cm (1 SD) and 0.01 +/- 0.33 cm in the anterior-posterior and superior-inferior direction, respectively. The corresponding figures for location of the apex were 0.05 +/- 0.30 cm and 0.01 +/- 0.33 cm, respectively. The statistical analysis revealed that a margin of 2 mm is sufficient to cover any random motion of the prostate that could occur as a result of the urethrogram 95% of the time. CONCLUSION: Urethrography during CT simulation for prostate cancer does not cause significant prostate displacement or systematic error in planning and delivering external-beam radiation.

Technical aspects of the deep inspiration breath-hold technique in the treatment of thoracic cancer.

PURPOSE: The goal of this paper is to describe our initial experience with the deep inspiration breath-hold (DIBH) technique in conformal treatment of non-small-cell lung cancer with particular emphasis on the technical aspects required for implementation. METHODS AND MATERIALS: In the DIBH technique, the patient is verbally coached through a modified slow vital capacity maneuver and brought to a reproducible deep inspiration breath-hold level. The goal is to immobilize the tumor and to expand normal lung out of the high-dose region. A physicist or therapist monitors and records patient breathing during simulation, verification, and treatment using a spirometer with a custom computer interface. Examination of internal anatomy during fluoroscopy over multiple breath holds establishes the reproducibility of the DIBH maneuver for each patient. A reference free-breathing CT scan and DIBH planning scan are obtained. To provide an estimate of tumor motion during normal tidal breathing, additional scan sets are obtained at end inspiration and end expiration. These are also used to set the spirometer action levels for treatment. Patient lung inflation is independently verified over the course of treatment by comparing the distance from the isocenter to the diaphragm measured from the DIBH digitally reconstructed radiographs to the distance measured on the portal films. Patient breathing traces obtained during treatment were examined retrospectively to assess the reproducibility of the technique. RESULTS: Data from the first 7 patients, encompassing over 250 treatments, were analyzed. The inferred displacement of the centroid of gross tumor volume from its position in the planning scan, as calculated from the spirometer records in over 350 breath holds was 0.02 +/- 0.14 cm (mean and standard deviation). These data are consistent with the displacements of the diaphragm (-0.1 +/- 0.4 cm; range, from -1.2 to 1.1 cm) relative to the isocenter, as measured on the (92) portal films. The latter measurements include the patient setup error. The patient averaged displacement of the tumor during free breathing, determined from the tumor displacement between end inspiration and end expiration, was 0.8 +/- 0.5 cm in both the superior-inferior and anterior-posterior directions and 0.1 cm (+/- 0.1 cm) medial-laterally. CONCLUSION: Treatment of patients with the DIBH technique is feasible in a clinical setting. With this technique, consistent lung inflation levels are achieved in patients, as judged by both spirometry and verification films. Breathing-induced tumor motion is significantly reduced using DIBH compared to free breathing, enabling better target coverage.

The deep inspiration breath-hold technique in the treatment of inoperable non-small-cell lung cancer.

PURPOSE: Conventional radiotherapeutic techniques are associated with lung toxicity that limits the treatment dose. Motion of the tumor during treatment requires the use of large safety margins that affect the feasibility of treatment. To address the control of tumor motion and decrease the volume of normal lung irradiated, we investigated the use of three-dimensional conformal radiation therapy (3D-CRT) in conjunction with the deep inspiration breath-hold (DIBH) technique. METHODS AND MATERIALS: In the DIBH technique, the patient is initially maintained at quiet tidal breathing, followed by a deep inspiration, a deep expiration, a second deep inspiration, and breath-hold. At this point the patient is at approximately 100% vital capacity, and simulation, verification, and treatment take place during this phase of breath-holding. RESULTS: Seven patients have received a total of 164 treatment sessions and have tolerated the technique well. The estimated normal tissue complication probabilities decreased in all patients at their prescribed dose when compared to free breathing. The dose to which patients could be treated with DIBH increased on average from 69.4 Gy to 87.9 Gy, without increasing the risk of toxicity. CONCLUSIONS: The DIBH technique provides an advantage to conventional free-breathing treatment by decreasing lung density, reducing normal safety margins, and enabling more accurate treatment. These improvements contribute to the effective exclusion of normal lung tissue from the high-dose region and permit the use of higher treatment doses without increased risks of toxicity.

Gaping lids, gp, a mutation on centromeric chromosome 11 that causes defective eyelid development in mice.

In mammals, during fetal development, the eyelids grow and flatten over the eyes and temporarily fuse closed. Failure of this normal developmental process in mice leads to the defect, open-eyelids-at-birth. Nearly all newborns of the GP/Bc strain, homozygous for the spontaneous recessive mutation, gaping lids (gp), have bilateral open eyelids at birth, with essentially no fusion between the upper and lower eyelids. Histological sections and scanning electron microscopy of GP/Bc eyes during the normal period of eyelid growth and fusion indicate that gp/gp mutant fetuses have deficient upper and lower eyelids; surface periderm cells that appear to have some role in eyelid growth and fusion are present, but lack a normal "streaming pattern toward the fusion zone. No other defects due to the gaping lids mutation were detected. A genetic analysis based on outcrosses of GP/Bc to various linkage marker stocks and to CBA/J and ICR/Bc normal strains was done. Penetrance in F(2) segregants, but not in BC1 segregants, was usually significantly less than 100%, was strongly affected by the identity of the normal strain used, ranging from 44% to 92%, and indicated a potential complexity of modifiers. Forty-one affected F(2) and 120 BC(1) segregants from the outcross of GP/Bc to CBA/J, and 23 affected F(2) segregants from the outcross to ICR/Bc, were used to map gp to proximal Chr 11 between the centromere and D11Dal1 (Camk2b), an interval previously defined as less than 1 cM. Sets of whole F(2) litters from the crosses to CBA/J (n = 106) and ICR/Bc (n = 65) strains were typed for informative SSLPs near gp (D11Mit62 and D11Mit74, respectively) and demonstrated that the segregation ratios in the region are Mendelian. The known genes in the interval, Nf2 and Lif, do not seem to be obvious candidate genes for gp. An Egfr-null allele was used to confirm the previously reported map position of the potential candidate locus, Egfr, to a more distal interval, between D11Mit62/226 and D11Mit151, from which gp had been excluded. Tests for allelism showed that the Egfr mutation and the gp mutation complement each other, and therefore also indicate that they are at different gene loci. Open-eyelids-at-birth is associated with several mutations at other loci with variable penetrance owing to modifiers and in other more complex genetic liabilities in inbred strains, and the genetics of this trait is a model for other genetically complex developmental threshold traits. The gaping lids mutation identifies a previously unknown locus on proximal Chromosome (Chr) 11 that has a strong role in fetal eyelid growth.

Summary of heritable ocular disorders and selected systemic conditions with eye findings.

A previously published table of ocular genetic disorders and inherited systemic conditions with eye findings has been updated with a comprehensive review of world literature. This tabulation of conditions is designed to provide a useful desk reference for practitioners and medical scientists. The summary will serve again as a benchmark of the significant advances that have occurred in the past few years.

Construction and characterization of a novel recombinant single-chain variable fragment antibody against Western equine encephalitis virus.

A novel recombinant single-chain fragment variable (scFv) antibody against Western equine encephalitis virus (WEE) was constructed and characterized. Using antibody phage display technology, a scFv was generated from the WEE specific hybridoma, 10B5 E7E2. The scFv was fused to a human heavy chain IgG1 constant region (CH1-CH3) and contained an intact 6 His tag and enterokinase recognition site (RS10B5huFc). The RS10B5huFc antibody was expressed in E. coli and purified by affinity chromatography as a 70-kDa protein. The RS10B5huFc antibody was functional in binding to WEE antigen in indirect enzyme-linked immunosorbent assays (ELISAs). Furthermore, the RS10B5huFc antibody was purified in proper conformation and formed multimers. The addition of the human heavy chain to the scFv replaced effector functions of the mouse antibody. The Fc domain was capable of binding to protein G and human complement. The above properties of the RS10B5huFc antibody make it an excellent candidate for immunodetection and immunotherapy studies.

Deep inspiration breath-hold technique for lung tumors: the potential value of target immobilization and reduced lung density in dose escalation.

PURPOSE/OBJECTIVE: This study evaluates the dosimetric benefits and feasibility of a deep inspiration breath-hold (DIBH) technique in the treatment of lung tumors. The technique has two distinct features--deep inspiration, which reduces lung density, and breath-hold, which immobilizes lung tumors, thereby allowing for reduced margins. Both of these properties can potentially reduce the amount of normal lung tissue in the high-dose region, thus reducing morbidity and improving the possibility of dose escalation. METHODS AND MATERIALS: Five patients treated for non-small cell lung carcinoma (Stage IIA-IIIB) received computed tomography (CT) scans under 4 respiration conditions: free-breathing, DIBH, shallow inspiration breath-hold, and shallow expiration breath-hold. The free-breathing and DIBH scans were used to generate 3-dimensional conformal treatment plans for comparison, while the shallow inspiration and expiration scans determined the extent of tumor motion under free-breathing conditions. To acquire the breath-hold scans, the patients are brought to reproducible respiration levels using spirometry, and for DIBH, modified slow vital capacity maneuvers. Planning target volumes (PTVs) for free-breathing plans included a margin for setup error (0.75 cm) plus a margin equal to the extent of tumor motion due to respiration (1-2 cm). Planning target volumes for DIBH plans included the same margin for setup error, with a reduced margin for residual uncertainty in tumor position (0.2-0.5 cm) as determined from repeat fluoroscopic movies. To simulate the effects of respiration-gated treatments and estimate the role of target immobilization alone (i.e., without the benefit of reduced lung density), a third plan is generated from the free-breathing scan using a PTV with the same margins as for DIBH plans. RESULTS: The treatment plan comparison suggests that, on average, the DIBH technique can reduce the volume of lung receiving more than 25 Gy by 30% compared to free-breathing plans, while respiration gating can reduce the volume by 18%. The DIBH maneuver was found to be highly reproducible, with intra breath-hold reproducibility of 1.0 (+/- 0.9) mm and inter breath-hold reproducibility of 2.5 (+/- 1.6) mm, as determined from diaphragm position. Patients were able to perform 10-13 breath-holds in one session, with a comfortable breath-hold duration of 12-16 s. CONCLUSION: Patients tolerate DIBH maneuvers well and can perform them in a highly reproducible fashion. Compared to conventional free-breathing treatment, the DIBH technique benefits from reduced margins, as a result of the suppressed target motion, as well as a decreased lung density; both contribute to moving normal lung tissue out of the high-dose region. Because less normal lung tissue is irradiated to high dose, the possibility for dose escalation is significantly improved.

Detective quantum efficiency of an amorphous selenium detector to megavoltage radiation.

The spatial frequency dependent detective quantum efficiency (DQE(f)) of a high-resolution selenium-based imaging system has been measured at megavoltage energies. These results have been compared with theoretical calculations. The imaging system was a video tube with a 5 microm amorphous selenium (a-Se) target which was irradiated by 1.25 MeV gamma-rays. The modulation transfer function (MTF) decreased rapidly with spatial frequency (determined by spread of electrons in the build-up material) while the noise power spectrum was constant as a function of spatial frequency. The DQE obtained from these MTF and noise power measurements was compared with a Monte Carlo model of the pulse height spectrum of the detector. The DQE(0) model accounted for the interaction of x rays with the detector as well as the energy-dependent gain (charge generated/energy deposition). Good agreement between the calculated and measured DQE(0) was found. The model was also used to estimate the DQE(f) of a metal plate + a-Se detector which was compared with a metal plate + phosphor system of the same mass thickness. The DQE(f) s of both detectors are very similar, indicating that the choice of which detector is better will be based upon criteria other than DQE(f), such as read-out approach, ease of manufacture or sensitivity.

A novel biological-based assay for the screening of neutralizing antibodies to ricin.

A novel approach to screen hybridomas producing antibodies directed against ricin was developed. Anti-ricin antibodies were produced and characterized based on protection of Sp2/mIL6 myeloma cells and in vivo studies demonstrating neutralization of the toxic effects of ricin in mice. During the production of hybridomas, cells were plated in media supplemented with hypoxanthine, aminopterin, and thymidine supplement (HAT), HAT + ricin, or ricin. Three hybridomas, designated HRF4, HHRD7 and HHRD9, were selected from the media supplemented with ricin and were shown to produce antibodies directed against ricin. Intraperitoneal injection of hybridoma supernatant containing anti-ricin antibodies combined with 0.5 microg ricin (a toxic dosage) protected Balb/C mice from the deleterious effects of the ricin. Hybridoma, HHRD9, did not contain high titre antibodies to ricin but appeared to neutralize the toxic effects of ricin in mice.