Glutamate is required to maintain the steady-state potassium pool in Salmonella typhimurium

In many bacteria, accumulation of K+ at high external osmolalities is accompanied by accumulation of glutamate. To determine whether there is an obligatory relationship between glutamate and K+ pools, we studied mutant strains of Salmonella typhimurium with defects in glutamate synthesis. Enteric bacteria synthesize glutamate by the combined action of glutamine synthetase and glutamate synthase (GS/GOGAT cycle) or the action of biosynthetic glutamate dehydrogenase (GDH). Activity of the GS/GOGAT cycle is required under nitrogen-limiting conditions and is decreased at high external ammonium/ammonia ((NH4)+) concentrations by lowered synthesis of GS and a decrease in its catalytic activity due to covalent modification (adenylylation by GS adenylyltransferase). By contrast, GDH functions efficiently only at high external (NH4)+ concentrations, because it has a low affinity for (NH4)+. When grown at low concentrations of (NH4)+ (< or = 2 mM), mutant strains of S. typhimurium that lack GOGAT and therefore are dependent on GDH have a low glutamate pool and grow slowly; we now demonstrate that they have a low K+ pool. When subjected to a sudden (NH4)+ upshift, strains lacking GS adenylyltransferase drain their glutamate pool into glutamine and grow very slowly; we now find that they also drain their K+ pool. Restoration of the glutamate pool in these strains at late times after shift was accompanied by restoration of the K+ pool and a normal growth rate. Taken together, the results indicate that glutamate is required to maintain the steady-state K+ pool -- apparently no other anion can substitute as a counter-ion for free K+ -- and that K+ glutamate is required for optimal growth.

Invariant U2 RNA sequences bordering the branchpoint recognition region are essential for interaction with yeast SF3a and SF3b subunits

U2 small nuclear RNA (snRNA) contains a sequence (GUAGUA) that pairs with the intron branchpoint during splicing. This sequence is contained within a longer invariant sequence of unknown secondary structure and function that extends between U2 and I and stem IIa. A part of this region has been proposed to pair with U6 in a structure called helix III. We made mutations to test the function of these nucleotides in yeast U2 snRNA. Most single base changes cause no obvious growth defects; however, several single and double mutations are lethal or conditional lethal and cause a block before the first step of splicing. We used U6 compensatory mutations to assess the contribution of helix III and found that if it forms, helix III is dispensable for splicing in Saccharomyces cerevisiae. On the other hand, mutations in known protein components of the splicing apparatus suppress or enhance the phenotypes of mutations within the invariant sequence that connect the branchpoint recognition sequence to stem IIa. Lethal mutations in the region are suppressed by Cus1-54p, a mutant yeast splicing factor homologous to a mammalian SF3b subunit. Synthetic lethal interactions show that this region collaborates with the DEAD-box protein Prp5p and the yeast SF3a subunits Prp9p, Prp11p, and Prp21p. Together, the data show that the highly conserved RNA element downstream of the branchpoint recognition sequence of U2 snRNA in yeast cells functions primarily with the proteins that make up SF3 rather than with U6 snRNA.

Dosimetric evaluation of the conformation of the multileaf collimator to irregularly shaped fields

PURPOSE

The goal of this study was to evaluate the dosimetric characteristics of geometric MLC prescription strategies and compare them to those of conventional shielding block.

METHODS AND MATERIALS

Circular fields, square fields, and 12 irregular fields for patients with cancer of the head and neck, lung, and pelvis were included in this study. All fields were shaped using the MLC and conventional blocks. A geometric criterion was defined as the amount of area discrepancy between the MLC and the prescription outline. The "least area discrepancy" (LAD) of the MLC conformation was searched by selecting the collimator angle, meanwhile keeping a preselected position along the width of the leaf into the prescribed field. Five LAD conventions were studied. These included the LAD-0, LAD-1/3, LAD-1/2, and LAD-2/3 that inserted the leaves at the 0, 1/3, 1/2, and 2/3 of the leaf end into the prescription field, respectively. In addition, the LAD optimization was applied to the transecting (TRN) approach for leaf conformation that prescribed an equal area of overblocking and underblocking under each leaf. Film dosimetry was performed in a 20 cm polystyrene phantom at 10 cm depth 100 cm from source to axis distance (SAD) for both 6 and 18 MV photons with each of the above MLC conformations and conventional blocks. The field penumbra width, defined as the mean of the separation between the 20% and 80% isodose lines along the normal of the prescription field edge, was calculated using both the MLC and conventional block film dosimetry and compared. In a similar way, the d20 is defined as the mean separation between the 20% isodose line and the prescription field edge, and the d80 is defined as the mean separation between the 80% isodose line and the prescription field edge.

RESULTS

The field penumbra width for all MLC conventions was approximately 2 mm larger than that of the conventional block. However, there was a larger variation of the separation distribution in the penumbra region of the irregular fields for the MLC, which had a standard deviation of 1 mm (a factor of 5 larger than the conventional block). The dosimetry for the circular fields showed that the LAD-TRN, LAD-1/2, and LAD-1/3 approximated the conventional blocking well in terms of d20 and d80; however, no single convention produced the best conformation for both measures. The dosimetric result of the patient treatment fields was similar for all sites. The LAD-1/3, LAD-1/2, and LAD-TRN strategies conformed to within 1 to 1.5 mm of the d80 of the conventional block for both 6 MV and 18 MV, respectively. The LAD-1/2 and LAD-TRN conformations were virtually identical, although it is proven analytically that the LAD-1/2 convention has the least overall area discrepancy of all conventions.

CONCLUSIONS

The five MLC conformation conventions resulted in similar dosimetric penumbrae for all field shapes studied. The LAD-1/3, LAD-TRN, and LAD-1/2 produced the more favorable approximation to conventional block. The field penumbra width, although useful for evaluating irregular field shapes, could not describe the large local variations in the penumbra along the field edge for the MLC. These local variations could be of clinical concern when they appear near vital organs. However, the variation in a local region can potentially be reduced by minimizing the jaggedness of the leaf steps in that local region. The dosimetric results were useful as guidelines for the clinicians in the evaluation and adjustment of MLC leaf positions.

Intraoperative optimization of needle placement and dwell times for conformal prostate brachytherapy

PURPOSE

Traditionally, transperineal prostate brachytherapy has been heavily operator dependent. To overcome this limitation, a treatment planning method was developed for intraoperative planning, guidance, and evaluation. In this setting, reliability, speed, and ease of understanding are primary considerations. This planning method has been implemented for ultrasound guided implants of the prostate, but can be extended for use in other body sites.

METHODS AND MATERIALS

The length and cross-section of the target (prostate) and location of urethra and rectum are determined intraoperatively from live ultrasound imaging. The planning program then automatically generates a "reference plan" containing needle locations, dwell times, and the resulting isodose distribution. As needles are placed, this information is corrected to account for any deviation of needle placement or movement of the prostate. Once all needles are in place, the normalization is adjusted to reconcile remaining hot-spots with coverage of the target volume. Optimization is performed in three separate stages. Each stage works to enhance only a subset of the implant parameters. (a) Pattern Optimization attempts to find the most appropriate placement for the needles or catheters. It is based on the transverse contour of the target volume. Needles are placed uniformly around the perimeter, and interior needle positions are determined from the cross-sectional area and shape. Critical structures such as the urethra are explicitly avoided. This step provides the overall framework for the implant, and is not generally repeated. (b) Relative Dwell Time Optimization selects relative dwell times that will give the best uniformity of dose. It works by setting the relative dwell time in each source position inversely proportional to the dose delivered to that point by the other source positions. It is used in the reference plan, and is repeated as each needle is inserted. This provides dosimetric feedback to the physician, who can judge the effect of deviations from the reference plan. (c) Relative Volume Optimization is an interactive method for fine tuning the normalization based upon volume analysis. The volume analysis is presented in tabular and graphical form, both being updated rapidly as the normalization is adjusted. The information is formatted to help the operator judge coverage and uniformity. Special functions are provided that allow the operator to "jump" to special normalization values based on several indices of uniformity or uniformity/coverage.

RESULTS

This system overcomes some conventional brachytherapy limitations. Rather than depend on the operator's intuitive judgement of where the needles should be placed, a global plan is generated and validated with full dose calculations. Immediate feedback is provided concerning the adequacy of placement and avoidance of critical structures. This information is provided in terms of actual tissue doses to the target volume and critical structures using point doses, isodose distributions, and volume analysis. Since the new method was introduced in January 1994, 33 implants have been performed. The needle placement method has been reliable in the clinic, with different doctors producing similar results on subsequent fractions for the same patient.

CONCLUSION

The method of decomposing the optimization problem into several simple steps is capable of rapidly, consistently, and reliably designing conformal treatment plans of high uniformity. Operator dependence has been significantly reduced. We are adapting the method for other anatomic sites.

The cumulative verification image analysis tool for offline evaluation of portal images

PURPOSE

Daily portal images acquired using electronic portal imaging devices contain important information about the setup variation of the individual patient. The data can be used to evaluate the treatment and to derive correction for the individual patient. The large volume of images also require software tools for efficient analysis. This article describes the approach of cumulative verification image analysis (CVIA) specifically designed as an offline tool to extract quantitative information from daily portal images.

METHODS AND MATERIALS

The user interface, image and graphics display, and algorithms of the CVIA tool have been implemented in ANSCI C using the X Window graphics standards. The tool consists of three major components: (a) definition of treatment geometry and anatomical information; (b) registration of portal images with a reference image to determine setup variation; and (c) quantitative analysis of all setup variation measurements. The CVIA tool is not automated. User interaction is required and preferred. Successful alignment of anatomies on portal images at present remains mostly dependent on clinical judgment. Predefined templates of block shapes and anatomies are used for image registration to enhance efficiency, taking advantage of the fact that much of the tool's operation is repeated in the analysis of daily portal images.

RESULTS

The CVIA tool is portable and has been implemented on workstations with different operating systems. Analysis of 20 sequential daily portal images can be completed in less than 1 h. The temporal information is used to characterize setup variation in terms of its systematic, random and time-dependent components. The cumulative information is used to derive block overlap isofrequency distributions (BOIDs), which quantify the effective coverage of the prescribed treatment area throughout the course of treatment. Finally, a set of software utilities is available to facilitate feedback of the information for treatment plan recalculation and to test various decision strategies for treatment adjustment.

CONCLUSIONS

The CVIA tool provides comprehensive analysis of daily images acquired with electronic portal imaging devices. Its offline approach allows characterization of the nature of setup variation for the individual patient that would have been difficult to deduce using only a few daily or weekly portal images. Distribution of the tool will help establish an important database of setup variation from many clinics. The information derived from CVIA can also serve as the foundation to integrate treatment verification, treatment planning, and treatment delivery.

Conformal prostate brachytherapy: initial experience of a phase I/II dose-escalating trial

PURPOSE

To improve treatment results on prostatic adenocarcinoma, conformal radiation therapy (CRT) has been used. Two major drawbacks of external CRT are: (a) internal organ motion/daily set-up variations, and (b) exclusion of several patients for CRT based on poor geometrical relationships as identified by three dimensional (3D) treatment planning. To overcome the above problems, we began the first prospective Phase I/II dose-escalating clinical trial of conformal brachytherapy (CB) and concurrent external beam irradiation.

METHODS AND MATERIALS

Fifty-nine patients with T2b-T3c prostatic adenocarcinoma received 176 transperineal ultrasound-guided conformal high-dose rate (HDR) boost implants. All patients received concomitant external beam pelvic irradiation. Dose escalation of the three HDR-CB fractions proceeded as follows: 5.5 Gy (30 patients), 6 Gy (20 patients), and 6.5 Gy (9 patients). The CB dose was prescribed to the prostate contour as outlined using an online biplanar transrectal ultrasound probe. The urethra, anterior rectal wall, and prostate boundaries were identified individually and outlined at 5 mm intervals from the base to the apex of the gland. The CB using real-time ultrasound guidance with interactive online isodose distributions was performed on an outpatient basis. As needles were placed into the prostate, corrections for prostate displacement were recorded and the isodose distributions were recalculated to represent the new relationship between the needles, prostate, and normal structures. No computerized tomography (CT) planning or implant preplanning was required.

RESULTS

No patient was rejected based on poor geometrical relation of pelvic structures. In every implant performed, prostate displacement was noted. Craniocaudal motion of the gland ranged from 0.5-2.0 cm (mean = 1.0 cm), whereas lateral displacement was 0.1-0.4 cm. With the interactive online planning system, organ motion was immediately detected, accounted for, and corrected prior to each HDR treatment. The rectal dose has ranged from 45 to 87%, and the urethral dose from 97 to 112% of the prostate dose. It is significant to note that operator dependence has been completely removed because the interactive online planning system uniformly guides the physicians.

CONCLUSIONS

With ultrasound guidance and the interactive online dosimetry system, organ motion (as compared to external beam) is insignificant because it can be corrected during the procedure without increasing target volume margins. Common pitfalls of brachytherapy, including operator dependence and difficulty with reproducibility, have been eliminated with the intraoperative online planning system.

Effects of treatment setup variation on beam's eye view dosimetry for radiation therapy using the multileaf collimator vs. the cerrobend block

PURPOSE

The purpose of this study is to quantify and compare retrospectively the effects of treatment setup variation on beam's eye view (BEV) dosimetry for radiation therapy using a multileaf collimator (MLC) vs. cerrobend block.

METHODS AND MATERIALS

A study was performed on a group of 18 patients with cancer of the head and neck, lung, and pelvis who were treated with irregularly shaped fields. The BEV dosimetry of the fields shaped with cerrobend blocks and the MLC was measured with films at the depth of dose prescription in a solid water phantom. A "one-half-leaf" insertion convention was used to shape the MLC. In addition, an average of 15 sequential daily port films was taken per patient during the course of radiotherapy. The port films were aligned with the prescription film for each patient. Systematic error and random error of treatment setup for each patient were calculated. The effects of setup variation were incorporated by convolving the patient portal imaging data with the corresponding BEV film dosimetry. Two parameters were used to quantify the BEV dosimetry. First, the field penumbra width was calculated, which represented the average of the normal separations between 20 and 80% isodose lines along the prescription outline. Second, the ratio of areas covered by the 90 and 20% isodose lines, A90/20, was determined. The BEV dosimetry was then characterized with and without the effects of treatment setup variation. In addition, the difference in BEV dosimetry between the cerrobend block and the MLC was used to estimate the corresponding changes in tumor control probability (TCP). These changes were also compared to the changes in TCP for the treatment with or without the effects of random setup variation.

RESULTS

With or without daily setup variation, the use of cerrobend block was more favorable than the MLC in terms of the field penumbra width and A90/20 for all treatment sites. In the absence of daily variation, the MLC field penumbra width was on average 1.3 mm larger than that of the cerrobend block, and 0.9 mm larger in the presence of daily setup variation. Similarly, the ratio A90/20 of the cerrobend block was on average 0.03 larger than that of MLC without daily setup variation, and 0.02 with daily setup variation. The difference in field penumbra width and A90/20 between the MLC and the cerrobend block was slightly reduced due to the effects of daily setup variation. For both the cerrobend block and the MLC, daily setup variation produced a significant increase in the field penumbra width, 2.3 mm for the cerrobend block and 1.9 mm for the MLC, and a decrease in the A90/20, 0.06 for the former and 0.05 for the latter. The change due to the daily setup variation was about a factor of 2 larger than the changes due to replacing the cerrobend block with the MLC. Using the TCP model, the change in TCP due to the daily setup variation was more than a factor of 3 larger than the change in TCP due to replacing the cerrobend block with the MLC. It was noted that the average changes in the penumbra, the A90/20 and the TCP calculated for the patient population did not adequately describe the changes for the individual patient.

CONCLUSION

Our results do not show significant dosimetric differences between the MLC and the cerrobend block in conventional radiation treatment, whether or not daily setup variation was taken into consideration. The effects of daily setup variation alone produced a larger dosimetric change. The same results were obtained when the data were applied to calculate changes in TCP. For optimal radiation therapy, efforts should be concentrated on reducing daily setup variation. Our results also demonstrate the importance of frequent evaluation of MLC treatment using electronic portal imaging devices.

[A study on the factors influencing bFGF to improve wound healing in severe burn]

The factors influencing basic fibroblast growth factor (bFGF) to improve wound healing in severe burn were studied. Rats were subjected to 15% III degrees burn. The results showed that high activity of bFGF was maintained after escharectomy in early period. In treated group 84.0% of rats wound healing was observed on the 40th day, while it was 9.0% in control group. Heparin could enhance activity of bFGF to stimulate formation of granulation tissue, regeneration of capillary, proliferation of fibroblast and DNA synthesis. Control of infection was beneficial to preserve activity of bFGF. The authors believe that the proper time to use bFGF is one week after injury.

[Cloning and sequencing of ntrBC genes from Azospirillum brasilense]

A gene library of Azospirillum brasilense Yu62 was constructed in EMBL3. The library was screened with PCR amplified fragment as a special probe. Ten positive plaques (EA1-EA10) were selected. Detection results showed they contained two different types of clones, representing as EA4 and EA9 respectively. Southern hybridization of EA4 displayed that target gene was located in a 2.9kb EcoRI fragment. Sequence of this fragment had allowed the position and identification of ntrC gene, which encoding a protein of 53469, consisted of 480 amino acids. In the upstream of ntrC, a complete ntrB coding region was also found, which encoding a protein of 43487, consisted of 400 amino acids. Homologous analysis of the deduced amino acid sequences of ntrC and ntrB from different bacteria demonstrated that A. brasilense was closer to Rhizobia than to other free-living diazotrophs.

A multileaf collimator field prescription preparation system for conventional radiotherapy

PURPOSE

The purpose of this work is to develop a prescription preparation system for efficient field shaping using a multileaf collimator that can be used in community settings as well as research institutions. The efficiency advantage of the computer-controlled multileaf collimator, over cerrobend blocks, to shape radiation fields has been shown in conformal treatments, which typically require complete volumetric computerized tomographic data for three-dimensional radiation treatment planning--a utility not readily available to the general community. As a result, most patients today are treated with conventional radiation therapy. Therefore, we believe that it is very important to fully use the same efficiency advantage of multileaf collimator as a block replacement in conventional practice.

METHODS AND MATERIAL

The multileaf collimator prescription preparation system developed by us acquires prescription images from different sources, including film scanner and radiation treatment planning systems. The multileaf collimator angle and leaf positions are set from the desired field contour defined on the prescription image, by minimizing the area discrepancies. Interactive graphical tools include manual adjustment of collimator angle and leaf positions, and definition of portions of the field edges that require maximal conformation. Data files of the final leaf positions are transferred to the multileaf collimator controller via a dedicated communication link.

RESULTS

We have implemented the field prescription preparation system and a network model for integrating the multileaf collimator and other radiotherapy modalities for routine treatments. For routine plan evaluation, isodose contours measured with film in solid water phantom at prescription depth are overlaid on the prescription image. Preliminary study indicates that the efficiency advantage of the MLC over cerrobend blocks in conformal therapy also holds true for conventional treatments.

CONCLUSION

Our model of computer-controlled prescription, evaluation, and treatment using multileaf collimators can be effectively implemented in both community settings and research institutions. The resultant increase in treatment efficiency and accuracy is now available for conventional radiotherapy.

A new model for "accept or reject" strategies in off-line and on-line megavoltage treatment evaluation

PURPOSE

With megavoltage on-line imaging, a temporal record of the treatment setup variation is made available during the course of radiotherapy. This work describes the theoretical framework where the imaging data is incorporated as feedback for deriving off-line and on-line "accept or reject" decisions to improve the quality of radiotherapy on an individual patient basis.

METHODS AND MATERIALS

A dynamic model of treatment setup variation is developed to describe: (a) the variations of multifraction treatment position and (b) the variation of measurement. Based on this model, a confidence region of subsequent treatment position is estimated from measurements of previous treatment position. The confidence region is compared with an allowance region of the treatment position, representing the acceptable margin of setup variation. The difference of the two regions are then evaluated to derive off-line and on-line "accept or reject" treatment decisions.

RESULTS

The model was simulated retrospectively using sequential daily images from different treatment sites. "Accept or reject" decisions were produced for on-line and off-line applications. The results also demonstrate the ability of the model to include the effects of setup variation that drifted during the course of treatment.

CONCLUSION

The preliminary result demonstrates that "accept or reject" treatment decisions can be derived quantitatively from on-line imaging data. The model shows potential to guide the physician and therapist in implementing efficient and accurate treatment adjustments. Further work is required to test the model in the clinical setting.

Optimization of leaf positions when shaping a radiation field with a multileaf collimator

Computer-controlled multileaf collimators are receiving increasing acceptance for clinical use in radiation therapy due to their efficiency in shaping radiation fields. Because of the physical leaf width of the multileaf collimator, a smooth field contour prescribed by a physician is approximated by a staircase-shaped field boundary. The point of intersection with the prescribed field contour determines the error of the approximation and may affect the outcome of the treatment. This article provides analytically optimized solutions for leaf positioning based on two different geometric object functions.

Flow cytometric analysis of the effects of in vitro exposure to vomitoxin (deoxynivalenol) on apoptosis in murine T, B and IgA+ cells

The immunotoxic effects of the trichothecene vomitoxin (VT or deoxynivalenol) and other trichothecenes may be mediated by direct interaction with lymphocytes. In this study, flow cytometric cell cycle analysis was used in conjunction with phenotypic staining by specific fluorescein isothiocyanate antibody conjugates to assess the in vitro effects of VT and another protein synthesis inhibitor, cycloheximide (CHX), on apoptosis in specific T- and B-cell subsets within thymus, spleen and Peyer's patch (PP) cultures. Both VT and CHX markedly inhibited T-cell apoptosis in dexamethasone (9 alpha-fluoro-16 alpha-methylprednisolone)-induced (DEX+) cells isolated from thymus, spleen and PP. Apoptosis-associated internucleosomal DNA fragmentation in whole thymus cell lysates as measured by gel electrophoresis was qualitatively consistent with flow cytometry among the various treatment groups. VT and CHX induced apoptosis in untreated (DEX-) T, B. and IgA+ cells from spleen and PP, whereas the effects of VT and CHX on DEX-induced apoptosis in B and IgA+ cells from these sources were negligible. These findings indicate that VT could either inhibit or enhance programmed cell death in a concentration-dependent manner and that this was dependent on lymphocyte subset, tissue source and glucocorticoid induction.

Integrated software tools for the evaluation of radiotherapy treatment plans

PURPOSE

This article announces the availability of a convenient and useful software environment for the evaluation of three-dimensional (3D) radiotherapy treatment plans.

MATERIALS AND METHODS

Using standards such as American National Standards for Information Systems C and the X Window System allowed us to bring the computation and display of dose-volume histograms, dose statistics, tumor control probabilities, normal tissue complication probabilities, and a figure of merit together under one user interface. These plan evaluation tools are not stand alone, but must interact with a 3D radiation therapy planning system to obtain the required dose matrices and patient anatomical contours. Installation of the software involves a programmer who writes a software bridge between the radiation therapy planning system and the tools, thereby providing access to local data files. This design strategy confines portability issues to one area of the software.

RESULTS

Access to the other tools is through the Graphical Plan Evaluation Tool (GPET). GPET coordinates the use of each of the tools and provides graphical facilities for display of their results. Importantly, GPET assures that the displayed results of each tool have been computed with the same input specifications for all treatment plans being compared. For added convenience, the user can rearrange the resultant data to be reviewed in various ways on the video screen. The software design also allows incorporation of customized algorithms and input data for computing tumor control probability and normal tissue complication probabilities, since those currently available are controversial.

CONCLUSION

The Graphical Plan Evaluation Tool unifies the simultaneous computation for several analytical tools and graphical display of their results. Within the constraints of the X Window System environment, this assemblage of software tools provides a portable, flexible, and convenient method for the quantitative evaluation of several radiotherapy treatment plans.

A multileaf collimator field prescription preparation system for conventional radiotherapy

PURPOSE

The purpose of this work is to develop a prescription preparation system for efficient field shaping using a multileaf collimator that can be used in community settings as well as research institutions. The efficiency advantage of the computer-controlled multileaf collimator, over cerrobend blocks, to shape radiation fields has been shown in conformal treatments, which typically require complete volumetric computerized tomographic data for three-dimensional radiation treatment planning--a utility not readily available to the general community. As a result, most patients today are treated with conventional radiation therapy. Therefore, we believe that it is very important to fully use the same efficiency advantage of multileaf collimator as a block replacement in conventional practice.

METHODS AND MATERIAL

The multileaf collimator prescription preparation systems developed by us acquires prescription images from different sources, including film scanner, and radiation treatment planning systems. The multileaf collimator angle and leaf positions are set from the desired field contour defined on the prescription image, by minimizing the area discrepancies. Interactive graphical tools include manual adjustment of collimator angle and leaf positions, and definition of portions of the field edges that require maximal conformation. Data files of the final leaf positions are transferred to the multileaf collimator controller via a dedicated communication link.

RESULTS

We have implemented the field prescription preparation system and a network model for integrating the multileaf collimator and other radiotherapy modalities for routine treatments. For routine plan evaluation, isodose contours measured with film in solid water phantom at prescription depth are overlaid on the prescription image. Preliminary study indicates that the efficiency advantage of the MLC over cerrobend blocks in conformal therapy also holds true for conventional treatments.

CONCLUSION

Our model of computer-controlled prescription, evaluation, and treatment using multileaf collimators can be effectively implemented in both community settings and research institutions. The resultant increase in treatment efficiency and accuracy is now available for conventional radiotherapy.

Recombinant ret oncogene products induce T-lymphocyte proliferation, and suppress lymphoma derived from ret transgenic mice

3Recombinant ret oncogene products in complete Freund's adjuvant were injected into normal mice and ret oncogene transgenic mice. Spleen cells from the mice immunized with ret proteins were highly proliferated in vitro by the stimulation of ret proteins. The proliferating T cells have CD4(+) phenotype and secreated CTLL-2 reactive interleukins. The peritoneal exudate cells from ret protein-immunized mice suppressed ret-2 lymphoma, which was derived from ret lymphoma transgenic mice. The peritoneal exudate cells from ret melanoma transgenic mice did not suppress ret-2 lymphoma, when they were immunized with ret proteins.

[The effect of medical treatment on hypertension community control--a follow-up study of more than one thousand hypertensives in East City Proper, Beijing]

Hypertension exerts a great threat on human health. Although most of countries promote the management of hypertension in communities, the role of treatment of hypertension is still controversial, it directly influences the strategy of hypertension community control. This study was based on the survey of essential and borderline hypertension in Gu-lou District of East City Proper, Beijing in 1981, and the management of 1339 hypertensives in the follow-up from 1982 to 1985, and the mortality registration in the district by Disease Surveillance System. By observing the prognosis within one year among different treatment groups (nonusers, less than 9 months and more than 9 months within one year), 1289 patients were followed up for a total of 4283 person-years. Crude analyses, stratified and logistic analyses with multi-variables adjustment of age, sex, blood pressure, with or without end-organ damage, etc. could not find that treatments had obvious effects on the reduction of incidence and mortality of stroke, mortality of CVD and all-cause in hypertensives except severe cases. The stratified analyses dy smoking also showed that smoking had a disadvantageous effects for treated hypertensives. Based on our results, we suggest that health education should be a major part of hypertension management program in community; treatments of hypertension should consider the flexible situation of patients and may not be a priority in hypertension community control program.

Automatic extraction and registration of shock wave fronts from series interferograms of a flow field

Algorithms for extracting shock wave fronts from interferograms of a flow field and for registering time-series shock waves are proposed. Based on these, application software is developed on a PC-Vision 100 image-processing system. As application examples, interferograms of a primary high-explosive flow field and a real, solid rocket muzzle flow field are processed. The results indicate that the propagation velocity of the shock wave can be easily calculated with this method.

Foot shock-induced changes in blood and brain serotonin and related substances in rats

The effects of electric foot shock on peripheral and central serotonergic systems in rats have been studied. We have focused on the time course alterations with particular attention being paid to changes in 5-HT, 5-HIAA, tryptophan concentrations and 5-HIAA/5-HT ratios in blood and various parts of the brain, observed within 1 h following stress application. Blood and brain (7 regions) samples were taken immediately after electric foot shock, 30 min, 1 and 24 h later. In the blood stress induced a rise in tryptophan level as well as rises in 5-HT, 5-HIAA levels and 5-HIAA/5-HT ratio within 1 h following stressful treatment. Tryptophan concentration was found to be increased in every part of the brain within 1 h after electric foot shock application. In striatum it remained higher even after 24 h. 5-HT level showed a significant rise only in medulla, while hypothalamus was the sole region where a fall in 5-HT was found. In other parts of the brain 5-HT level remained unaffected by stress. 5-HIAA content increased in almost every brain area studied except cerebellum and striatum. 5-HIAA/5-HT ratios shared the same pattern of changes. Briefly, foot shock altered 5-HT turnover in various brain regions, in particular within the first hour following stress application, whereas delayed response to stress was rarely observed. Increased brain tryptophan level seems to be necessary to cope with the enhanced 5-HT metabolism caused by stress, reflecting as a rise in 5-HIAA concentration and 5-HIAA/5-HT ratio.

An evaluation of two methods of anatomical alignment of radiotherapy portal images

PURPOSE

Two techniques have been developed at our institution to allow anatomical registration of digitized portal images to a simulation film. Accuracy of the portal image alignment methods is tested and single intrauser and multiple interuser variation is examined using each technique.

METHODS AND MATERIALS

Method one requires the identification of anatomical fiducial points on a simulation image and its corresponding portal image. The parameters required to align the corresponding points are calculated by a least squares fit algorithm. Method two uses an anatomical template generated from the simulation image and superimposing it upon a portal image. The template is then adjusted by a computer mouse to obtain the best subjective anatomical fit on the portal image. Megavoltage portal images of a skull phantom with various known shifts and eight clinical image files were aligned by each method. Each data set was aligned several times by both a single user and multiple users.

RESULTS

Alignment of the anatomical phantom portal images demonstrates an accuracy of less than 0.8 +/- 0.9 mm and 0.7 +/- 1.0 degrees with either method. As out of plane rotation increased from 0 to 5 degrees, simulating out of plane malpositioning, alignment orthogonal to the plane of rotation worsened to 1.5 +/- 1.1 mm with the point method and 2.4 +/- 1.6 mm with the template method. Alignment parallel to the axis of the gantry rotation was insensitive to this change and remained constant as did the rotational alignment parameters. For the clinical image files the magnitude of variation for a single user is typically less than +/- 1 mm or +/- 1 degree. The magnitude of variation of alignment increased when multiple users aligned the same image files. The variation was dependent upon anatomical site and to a lesser degree the method of alignment used. The root mean square deviation of translational shifts range from +/- 0.68 mm when using the template method in the pelvis to as high as +/- 2.94 mm with the template method to align abdominal portal images. In the thorax and pelvis translational alignments along the horizontal axis were more precise than along the vertical axis. Multiple user variability was in part due to poor image quality, user experience, non rigidity of the anatomical features, and the difficulty in locating an exact point on a continuous anatomical structure.

CONCLUSION

In well controlled phantom studies both the fiducial point and template method provide similar and adequate results. The phantom studies show that alignment error and variance increase with distortion in anatomical features secondary to out of plane rotations. In clinical situations intrauser variation is small, however, multiple interuser variation is larger. The magnitude of variation is dependent upon the anatomical site aligned.

The use of on-line image verification to estimate the variation in radiation therapy dose delivery

PURPOSE

On-line radiotherapy imaging systems provide data that allow us to study the geometric nature of treatment variation. It is more clinically relevant to examine the resultant dosimetric variation. In this work, daily beam position as recorded by the on-line images is used to recalculate the treatment plan to show the effect geometric variation has on dose.

METHODS AND MATERIALS

Daily 6 MV or 18 MV x-ray portal images were acquired using a fiberoptic on-line imaging system for 12 patients with cancers in the head and neck, thoracic, and pelvic regions. Each daily on-line portal image was aligned with the prescription simulation image using a template of anatomical structures defined on the latter. The outline of the actual block position was then superimposed on the prescription image. Daily block positions were cumulated to give a summary image represented by the block overlap isofrequency distribution. The summary data were used to analyze the amount of genometric variation relative to the prescription boundary on a histogram distribution plot. Treatment plans were recalculated by considering each aligned portal image as an individual beam.

RESULTS

On-Line Image Verification (OLIV) data can differentiate between systematic and random errors in a course of daily radiation therapy. The data emphasize that the type and magnitude of patient set-up errors are unique for individual patients and different clinical situations. Head and neck sites had the least random variation (average 0-100% block overlap isofrequency distribution width = 7 mm) compared to thoracic (average 0-100% block overlap isofrequency distribution width = 12 mm) or pelvic sites (average 0-100% block overlap isofrequency distribution width = 14 mm). When treatment delivery is analyzed case by case, systematic as well as random errors are represented. When the data are pooled by anatomical site, individuality of variations is lost and variation appears random. Recalculated plans demonstrated dosimetric deviations from the original plans. The differences between the two dosimetric distributions were emphasized using a technique of plan subtraction. This allowed quick identification of relative "hot and cold spots" in the recalculated plans. The magnitude and clinical significance of dosimetric variation was unique for each patient.

CONCLUSIONS

OLIV data are used to study geometric uncertainties because of the unique nature for individual patients. Dose recalculation is helpful to illustrate the dosimetric consequences of set-up errors.

Dissociation of alpha 2-plasmin-inhibitor-plasmin complex and regeneration of plasmin activity by SDS treatment

In order to understand the mechanism for the complex between alpha 2-plasmin-inhibitor (alpha 2-PI) and plasmin to express its specific activity on fibrin autography after SDS-PAGE, we analyzed the effects of SDS on alpha 2-PI molecule and alpha 2-PI-plasmin complex. Treatment of alpha 2-PI by SDS at the concentrations of 0.01% and 0.1% abolished the activity of alpha 2-PI to form a stoichiometric complex with plasmin, whereas it did not interfere with plasmin's activity. More interestingly, in the case of 0.01% SDS, alpha 2-PI was further cleaved to a smaller molecule. Treatment of previously formed alpha 2-PI-plasmin complex by SDS at the concentrations of both 0.01% and 0.1% dissociated the complex and expressed specific amidolytic activity against tripeptide substrate (S-2251), which activity was totally quenched by aprotinin. When alpha 2-PI-plasmin complex was treated by higher concentration of SDS for 12 hours, dissociated free plasmin's band could be observed on SDS-PAGE analysis. It is likely, therefore, that the exposure of alpha 2-PI-plasmin complex to SDS during the procedure of SDS-PAGE dissociates the complex and expresses its specific proteolytic activity in fibrin autography. These features of alpha 2-PI and its complex with plasmin are similar to those of plasminogen activator inhibitor type 1 (PAI-1) and its complex with plasminogen activators (PAs), thus they may represent some common features of the SERPINS.

Interleukin-2-responsive wound-infiltrating lymphocytes in surgical adjuvant cancer immunotherapy

Wound-infiltrating lymphocytes (WIL) were assessed in murine models of localized sarcoma and carcinoma to evaluate the role of interleukin-2 (IL-2)-responsive lymphocytes in adjuvant immunotherapy. Following tumor resection, IL-2 or diluent was injected at the surgical site for 6 days. Surgical site tissues were harvested and digested in a triple enzyme mixture, and single cell suspensions were prepared. Thy 1.2+ lymphocytes were isolated by incubating cells with monoclonal anti-Thy 1.2 antibody-coated magnetic beads. Lymphocyte-bead complexes were extracted with a magnet and cultured in medium containing IL-2 (100 units/ml) for 1-3 weeks. Perioperative IL-2 immunotherapy led to a three- to four-fold increase in WIL yield. WIL from IL-2-treated mice also demonstrated enhanced cytolysis of the autologous tumor and bound to activated endothelial cells with greater avidity than did the controls. We conclude that perioperative IL-2 therapy augments the yield, as well as the cytolytic and adhesive properties, of wound-infiltrating lymphocytes.

Correlation between serotonergic measures in cerebrospinal fluid and blood of subhuman primate

The relationship between the concentration of serotonin (5-hydroxytryptamine; 5-HT), its precursor; tryptophan (Trp) and the main metabolite 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF) and blood of monkey have been studied. 5-HT, Trp and 5-HIAA underwent circadian changes in both CSF and blood. Significant correlations were found between 5-HT, 5-HIAA and Trp in CSF and blood. The significance of these findings and their relationship to the use of peripheral serotonergic system as a functional model of the central nervous system are discussed.

Serotonergic measures in blood and brain and their correlations in rats treated with tranylcypromine, a monoamine oxidase inhibitor

Tranylcypromine, a monoamine oxidase inhibitor, was administered to male Wistar rats in order to investigate its effects on blood and brain serotonin related substances after 1, 4, and 24 h following injection and possible relations between serotonergic measures in central nervous system and periphery. The dose of the drug tested was responsible for an increase in blood serotonin with a simultaneous fall in its metabolite 5-hydroxyindoleacetic acid (5-HIAA) compared to either pretreatment or control values. These changes were the most marked after 4 and 24 h following tranylcypromine injection. Almost all brain areas studied (cerebellum, medulla, hypothalamus, striatum, midbrain, hippocampus, and cortex) were to be affected by monoamine oxidase inhibitor treatment. They exhibited a rise in serotonin content starting from 1 h after drug administration and lasted in many parts of the brain up to 24 h, which was accompanied by a parallel fall in 5-HIAA level. All these changes were significant when compared to baseline and control values. Alterations in blood serotonin correlated positively with changes in brain serotonin and negatively with brain 5-HIAA, while the opposite pattern of correlations was found regarding blood 5-HIAA and the content of serotonin and 5-HIAA in various brain areas studied. This pattern of correlations speaks in favor of an existence of mutual relations between blood and brain serotonin related substances. Our results suggest that blood serotonin and 5-HIAA may serve as an index of monoamine oxidase inhibitor action on the central serotonergic system.

[Primary analysis on hypertension community control in East City]

In order to carry out chronic disease prevention, a hypertension community control program has been conducted in Disease Surveillance Point, East City. Beijing since 1989. The resident committees were randomly divided into two groups. The community control activities were conducted in intervention group, which included home visit, health education. 3190 hypertensive cases were managed in 1991. Current smoking rate was decreased 8.37%, quit and reduce smoking increased 5.81%, drinking decreased 8.77%, reduced salt intake 5.45%, DBP < 95 mmHg increased 27.81%, when compared with base line survey in 1989. These indicators were significant between intervention and control groups. It means hypertension community control program is successful.

Relationship between serotonergic measures in periphery and the brain of mouse

Circadian rhythm and the relationship between the concentration of serotonin (5HT) and related substances (5-hydroxyindoleacetic acid; 5HIAA and tryptophan; Trp) in mouse brain, stomach and blood have been studied. All factors underwent circadian changes in the brain and blood. 5HT and 5HIAA levels in the stomach showed no circadian fluctuation. The concentrations of 5HT in the brain and blood did not correlate. Significant correlations were found between other serotonergic parameters analyzed in brain, stomach and blood. A significant negative correlation was observed between brain 5HIAA and blood 5HIAA. The concentration of tryptophan in the brain was correlated with the plasma total tryptophan level. There was fairly significant correlation (p less than 0.06) between brain serotonin and plasma tryptophan levels. The brain serotonin and tryptophan levels were strongly correlated (R = 0.410, p less than 0.03). Significant negative correlation was found between serotonin in the blood and serotonin in the stomach as well as between its level in the brain and in the stomach. The significance of these findings and their relationship to the use of peripheral serotonergic system as a model of neurons are discussed.

Marek's disease virus gene clones encoding virus-specific phosphorylated polypeptides and serological characterization of fusion proteins

Marek's disease virus (MDV) gene clones, RA2 and GA8, constructed in E. coli bacteriophage lambda-gt11 (gt11) were identified by a monoclonal antibody (MAb), H19.47, against a putative transformation-related viral antigen consisting of a complex of three phosphorylated polypeptides, pp41, pp38, and pp24. Both recombinants have a MDV-DNA insert of about 0.5 kb and are mapped to the region of BamHI-H or EcoRI-X fragments of the MDV genome by Southern blot hybridization. Immunoblot and immunoprecipitation with H19.47 identified a recombinant beta-galactosidase-MDV 140-kD fusion protein for RA2 and a 127-kD fusion protein for GA8. Immunoprecipitation of 35S-methionine-labeled, MDV-infected chicken embryo fibroblasts (CEF) with antisera against RA2 and GA8 fusion proteins recognized five polypeptides, of which three (p41, p38, and p24) are specified by H19.47 and the remaining two, p135 and p20, have not been previously identified. Immunoprecipitation of 32P-phosphate-labeled or 3H-glucosamine-labeled, GA-MDV-infected CEF with the antiserum against RA2 fusion protein identified a phosphorylated polypeptide of 38 kD and two glycoproteins of 60 and 49 kD, respectively. The antisera against recombinant fusion proteins thus revealed the existence of epitopes common to the phosphorylated polypeptides and other MDV-specific polypeptides. Sera from chickens or mice hyperimmunized with the purified fusion proteins reacted with serotype 1, MDV-infected CEF in the fluorescent antibody (FA) test to significant titers. These immune sera did not react with either serotype II or III, indicating the serotype specificity of the phosphorylated polypeptides.

Effects of atmospheric turbulence on photodetector arrays

In this paper we study quantitatively the effects of atmospheric turbulence on the measurement sensitivity of a quadrant detecting array, along with the measurement variance induced by atmospheric turbulence. Our results show that the stronger the turbulence strength, the lower the measurement sensitivity, and the larger the measurement variance. This agrees with the experimental phenomena we have observed up to now. In addition, the measurement sensitivity in the X direction could be affected by the deviation of light spots in the Y direction due to the existence of gaps between the quadrant elements. Such effects still exist for the measurement variance even when there are no gaps at all. This effect is analyzed quantitatively.

Studies on immunopathogenesis in epidemic hemorrhagic fever: sequential observations on activation of the first complement component in sera from patients with epidemic hemorrhagic fever

Sequential measurements of activation of the 1st component of complement (C1) in the sera of 29 patients hospitalized with epidemic hemorrhagic fever (EHF) were performed according to a method recently developed. These patients were treated with supportive, routine therapy, but not immunosuppressive agents. This paper describes the kinetic observations on the activation of C1 in the 29 cases. The data confirm that an apparently increased extent of activation occurred in their sera. It was found that the more severely ill the patients were, the more apparent the activation. Additionally, beginning with the 15th day of disease, the extent of C1 activation diminished in most of the moderate and severe types of patients, but not in those with moribund illness and fatal ones. On the basis of the study, it may be reasonably concluded that C1 activation was correlated well with the severity and clinical course of EHF, indicating that the classical C pathway was activated in these patients. We feel that our findings are important to an understanding and elucidation of the immunopathogenetic mechanisms of EHF.

Studies on immunopathogenesis in epidemic hemorrhagic fever: sequential observations on activation of the first complement component in sera from patients with epidemic hemorrhagic fever

Sequential measurements of activation of the 1st component of complement (C1) in the sera of 29 patients hospitalized with epidemic hemorrhagic fever (EHF) were performed according to a method recently developed. These patients were treated with supportive, routine therapy, but not immunosuppressive agents. This paper describes the kinetic observations on the activation of C1 in the 29 cases. The data confirm that an apparently increased extent of activation occurred in their sera. It was found that the more severely ill the patients were, the more apparent the activation. Additionally, beginning with the 15th day of disease, the extent of C1 activation diminished in most of the moderate and severe types of patients, but not in those with moribund illness and fatal ones. On the basis of the study, it may be reasonably concluded that C1 activation was correlated well with the severity and clinical course of EHF, indicating that the classical C pathway was activated in these patients. We feel that our findings are important to an understanding and elucidation of the immunopathogenetic mechanisms of EHF.