Radiation Therapy Quality Assurance Analysis of Alliance A021501: Preoperative mFOLFIRINOX or mFOLFIRINOX Plus Hypofractionated Radiation Therapy for Borderline Resectable Adenocarcinoma of the Pancreas

PURPOSE

Alliance A021501 is the first randomized trial to evaluate stereotactic body radiation therapy (SBRT) for borderline resectable pancreatic ductal adenocarcinoma (PDAC) after neoadjuvant chemotherapy. In this post hoc study, we reviewed the quality of radiation therapy (RT) delivered.

METHODS AND MATERIALS

SBRT (6.6 Gy × 5) was intended but hypofractionated RT (5 Gy × 5) was permitted if SBRT specifications could not be met. Institutional credentialing through the National Cancer Institute-funded Imaging and Radiation Oncology Core (IROC) was required. Rigorous RT quality assurance (RT QA) was mandated, including pretreatment review by a radiation oncologist. Revisions were required for unacceptable deviations. Additionally, we performed a post hoc RT QA analysis in which contours and plans were reviewed by 3 radiation oncologists and assigned a score (1, 2, or 3) based on adequacy. A score of 1 indicated no deviation, 2 indicated minor deviation, and 3 indicated a major deviation that could be clinically significant. Clinical outcomes were compared by treatment modality and by case score.

RESULTS

Forty patients were registered to receive RT (1 planned but not treated) at 27 centers (18 academic and 9 community). Twenty-three centers were appropriately credentialed for moving lung/liver targets and 4 for static head and neck only. Thirty-two of 39 patients (82.1%) were treated with SBRT and 7 (17.9%) with hypofractionated RT. Five cases (13%) required revision before treatment. On post hoc review, 23 patients (59.0%) were noted to have suboptimal contours or plan coverage, 12 (30.8%) were scored a 2, and 11 (28.2%) were scored a 3. There were no apparent differences in failure patterns or surgical outcomes based on treatment technique or post hoc case score. Details related to on-treatment imaging were not recorded.

CONCLUSIONS

Despite rigorous QA, we encountered variability in simulation, contouring, plan coverage, and dose on trial. Although clinical outcomes did not appear to have been affected, findings from this analysis serve to inform subsequent PDAC SBRT trial designs and QA requirements.

Local Control For High-Grade Nonrhabdomyosarcoma Soft Tissue Sarcoma Assigned to Radiation Therapy on ARST0332: A Report From the Childrens Oncology Group

PURPOSE

The ARST0332 trial for pediatric and young adults with nonrhabdomyosarcoma soft tissue sarcoma (NRSTS) used risk-based treatment including primary resection with lower-than-standard radiation doses to optimize local control (LC) while minimizing long-term toxicity in those requiring radiation therapy (RT). RT for high-grade NRSTS was based on extent of resection (R0: negative margins, R1: microscopic margins, R2/U: gross disease/unresectable); those with >5 cm tumors received chemotherapy (CT; ifosfamide/doxorubicin). This analysis evaluates LC for patients assigned to RT and prognostic factors associated with local recurrence (LR).

METHODS AND MATERIALS

Patients aged <30 years with high-grade NRSTS received RT (55.8 Gy) for R1 ≤5 cm tumor (arm B); RT (55.8 Gy)/CT for R0/R1 >5 cm tumor (arm C); or neoadjuvant RT (45 Gy)/CT plus delayed surgery, CT, and postoperative boost to 10.8 Gy R0 <5 mm margins/R1 or 19.8 Gy for R2/unresected tumors (arm D).

RESULTS

One hundred ninety-three eligible patients had 24 LRs (arm B 1/15 [6.7%], arm C 7/65 [10.8%], arm D 16/113 [14.2%]) at median time to LR of 1.1 years (range, 0.11-5.27). Of 95 eligible for delayed surgery after neoadjuvant therapy, 89 (93.7%) achieved R0/R1 margins. Overall LC after RT were as follows: R0, 106 of 109 (97%); R1, 51 of 60 (85%); and R2/unresectable, 2 of 6 (33%). LR predictors include extent of delayed resection (P <.001), imaging response before delayed surgery (P < .001), histologic subtype (P <.001), and no RT (P = .046). The 5-year event-free survival was significantly lower (P = .0003) for patients unable to undergo R0/R1 resection.

CONCLUSIONS

Risk-based treatment for young patients with high-grade NRSTS treated on ARST0332 produced very high LC, particularly after R0 resection (97%), despite lower-than-standard RT doses. Neoadjuvant CT/RT enabled delayed R0/R1 resection in most patients and is preferred over adjuvant therapy due to the lower RT dose delivered.

MBCL-15. IMPACT OF MOLECULAR SUBGROUPS ON OUTCOMES FOLLOWING RADIATION TREATMENT RANDOMIZATIONS FOR AVERAGE RISK MEDULLOBLASTOMA: A PLANNED ANALYSIS OF CHILDREN’S ONCOLOGY GROUP (COG) ACNS0331

The COG conducted a randomized trial for average-risk medulloblastoma (AR-MB). Patients age 3–21 years were randomized to a radiation boost to the whole posterior fossa (PFRT) or an involved field volume (IFRT) after receiving CSI. Patients age 3–7 years were also randomized to standard dose CSI (23.4Gy, SDCSI) or low dose CSI (18Gy, LDCSI). 464 evaluable patients were available to compare PFRT vs. IFRT and 226 for SDCSI vs. LDCSI. 380 cases had sufficient tissue for DNA methylation-based molecular classification: 362 confirmed medulloblastoma; 6 non-medulloblastoma; 12 inconclusive. Molecular subgrouping confirmed the following representation amongst the evaluable cohort: 156 Group 4 (43.1%), 76 Group 3 (21.0%), 66 SHH (18.2%), 64 WNT (17.7%). Five-year event-free survival (EFS) estimates were 82.5±2.7% and 80.5±2.7% for IFRT and PFRT, respectively (p=0.44). Five-year EFS estimates were 71.4±4.4% and 82.9±3.7% for LDCSI and SDCSI, respectively (p=0.028). EFS distributions differed significantly by subgroup (p&lt;0.0001). Group 3 had the worst outcome, while WNT had the best outcome. There was a significant difference in EFS by RT group among SHH patients; SHH patients receiving IFRT arm had better EFS compared to PFRT (p=0.018). There was a significant difference in EFS distributions by CSI group in Group 4 patients; young Group 4 patients treated with SDCSI had better EFS compared to LDCSI (p=0.047). As previously reported, IFRT is noninferior to PFRT in all patients with AR-MB but LDCSI is worse than SDCSI in younger children. Significant differences in outcome by study randomization and molecular subgroup are observed.

The rates of second lung cancers and the survival of surgically-resected second primary lung cancers in patients undergoing resection of an initial primary lung cancer

BACKGROUND

The Lung Cancer Screening Trial demonstrated improved overall survival (OS) and lung cancer specific survival (LCSS), likely due to finding early-stage NSCLC. The purpose of our investigation is to evaluate whether long-term surveillance strategies (4+ years after surgical resection of the initial lung cancer(1LC)) would be beneficial in NSCLC patients by assessing the rates of second lung cancers(2LC) and the OS/LCSS in patients undergoing definitive surgery in 1LC as compared to 2LC (>48 months after 1LC) populations.

METHODS

SEER13/18 database was reviewed for patients during 1998-2013. Log-rank tests were used to determine the OS/LCSS differences between the 1LC and 2LC in the entire surgical group(EG) and in those having an early-stage resectable tumors (ESR, tumors <4 cm, node negative). Joinpoint analysis was used to determine rates of second cancers 4-10 year after 1LC using SEER-9 during years 1985-2014.

RESULTS

The rate of 2LCs was significantly less than all other second cancers until 2001 when the incidence of 2LCs increased sharply and became significantly greater than all other second cancers in females starting in year 2005 and in men starting in year 2010. OS/LCSS, adjusted for propensity score by using inverse probability weighting, demonstrated similar OS, but worse LCSS for 2LCs in the EG, but similar OS/LCSSs in the ESR group.

CONCLUSION

Because the rate of 2LCs are increasing and because the OS/LCSS of the 1LC and 2LC are similar in early-stage lesions, we feel that continued surveillance of patients in order to find early-stage disease may be beneficial.

Open access image repositories: high-quality data to enable machine learning research

Originally motivated by the need for research reproducibility and data reuse, large-scale, open access information repositories have become key resources for training and testing of advanced machine learning applications in biomedical and clinical research. To be of value, such repositories must provide large, high-quality data sets, where quality is defined as minimising variance due to data collection protocols and data misrepresentations. Curation is the key to quality. We have constructed a large public access image repository, The Cancer Imaging Archive, dedicated to the promotion of open science to advance the global effort to diagnose and treat cancer. Drawing on this experience and our experience in applying machine learning techniques to the analysis of radiology and pathology image data, we will review the requirements placed on such information repositories by state-of-the-art machine learning applications and how these requirements can be met.

IL-1 generated subsequent to radiation-induced tissue injury contributes to the pathogenesis of radiodermatitis

Radiation injury in the skin causes radiodermatitis, a condition in which the skin becomes inflamed and the epidermis can break down. This condition causes significant morbidity and if severe it can be an independent factor that contributes to radiation mortality. Radiodermatitis is seen in some settings of radiotherapy for cancer and is also of concern as a complication post-radiation exposure from accidents or weapons, such as a "dirty bomb". The pathogenesis of this condition is incompletely understood. Here we have developed a murine model of radiodermatitis wherein the skin is selectively injured by irradiation with high-energy electrons. Using this model we showed that the interleukin-1 (IL-1) pathway plays a significant role in the development of radiodermatitis. Mice that lack either IL-1 or the IL-1 receptor developed less inflammation and less severe pathological changes in their skin, especially at later time-points. These findings suggest that IL-1 pathway may be a potential therapeutic target for reducing the severity of radiodermatitis.

Quality assurance review center: Role in multi-institutional breast cancer trials

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Background: Central review is an important trial management and validation tool. Multisite trials require data systems to accommodate diverse image acquisition and review. Breast cancer is challenging as its imaging objects are not always easily shared across departments. Quality Assurance Review Center (QARC) has a diverse portfolio of facile data acquisition and powerful informatics support that meets these needs. We report on the role of QARC in three of the current breast cancer trials from the American College of Surgeons Oncology Group.

Methods: QARC data management system includes secure network infrastructure and a validated relational operating database (MAX). QARC has data acquisition/imaging re-distribution expertise for real time response reviews, response measuring tools and corresponding data archive for secondary reviews. MAX includes query ability; records link to digital information. QARC underwent systematic information systems validation process for 21 CFR Part 11. DICOM/non-DICOM files are stored in the QARC PACS. On-site/remote reviewers use MAX to retrieve, view, annotate and save images. Data extracted is securely sent to partner statistical centers.

Results: In Z1031, a neoadjuvant endocrine therapy trial, all of the mammographic exams are archived at QARC. For Z1071, a sentinel lymph node trial, pre- and post-treatment ultrasound (US) images of 321 patients were remotely reviewed. For Z1072, the cryoablation US, pre and post-cryoablation MRI for 40 of 47 cases were remotely archived, retrieved and transferred to investigator workstation for post-processing and review. The other 7 patients did not have evaluable imaging studies. In all three trials, the costs of shipping hardcopies of exams and travel to QARC for central review functions were eliminated.

Conclusions: QARC data management systems provide diverse informatics supports for multi-institutional trials, ranging from archives of images, provide remote access and download of data, and central review. The vibrant informatics supports meet the growing needs of clinical trials. Future directions include radiation field review for breast cancer trials and the incorporation of pathology microarray analysis as DICOM objects.

Initial experience with volumetric IMRT (RapidArc) for intracranial stereotactic radiosurgery

PURPOSE

Initial experience with delivering frameless stereotactic radiotherapy (SRT) using volumetric intensity-modulated radiation therapy (IMRT) delivered with RapidArc is presented.

METHODS AND MATERIALS

Treatment details for 12 patients (14 targets) with a mean clinical target volume (CTV) of 12.8 ± 4.0 cm(3) were examined. Dosimetric indices for conformality, homogeneity, and dose gradient were calculated and compared with published results for other frameless, intracranial SRT techniques, including CyberKnife, TomoTherapy, and static-beam IMRT. Statistics on setup and treatment times and per patient dose validations were examined.

RESULTS

Dose indices compared favorably with other techniques. Mean conformality, gradient, and homogeneity index values were 1.10 ± 0.11, 64.9 ± 14.1, 1.083 ± 0.026, respectively. Median treatment times were 4.8 ± 1.7 min.

CONCLUSION

SRT using volumetric IMRT is a viable alternative to other techniques and enables short treatment times. This is anticipated to have a positive impact on radiobiological effect and for facilitating wider use of SRT.

Prostate carcinoma and radiation therapy: therapeutic treatment resistance and strategies for targeted therapeutic intervention

Adenocarcinoma of the prostate remains a significant public health problem and a prevalent cancer in men. Prostate-specific antigen used as a biomarker has established a clear migration of patients towards earlier-stage disease at presentation. However, in spite of process improvements in traditional therapies including surgery, radiation therapy, and hormone management, there remains a significant cohort of patients with intermediate- to high-risk features for poor outcome in spite of optimal use of traditional management. This paper focuses on future treatment strategies integrating new therapeutic options with traditional management, specifically to pinpoint new radiation therapy strategies.

Interruptions of once-daily thoracic radiotherapy do not correlate with outcomes in limited stage small cell lung cancer: analysis of CALGB phase III trial 9235

PURPOSE

Retrospective data suggests prolonging the time to complete thoracic radiotherapy (TRT) may negatively impact tumor control and survival in limited stage small cell lung cancer (LSCLC). We examined the association between TRT duration and outcomes on a prospective phase III study.

MATERIAL AND METHODS

This review included 267 patients who received protocol TRT on a phase III CALGB LSCLC study assessing the addition of tamoxifen to standard chemo-radiotherapy. TRT, to a planned dose of 50Gy in 2Gy daily fractions, was initiated with the fourth chemotherapy cycle. TRT interruptions were mandated for hematologic toxicity (granulocytes<1000/mm3 or platelets<75,000/mm3) and esophageal toxicity (dysphagia necessitating intravenous hydration).

RESULTS

TRT interruptions > or =3 days occurred in 115 patients (43%), most frequently during the 4th week of TRT, and did not differ between treatment arms. Hematologic toxicity and esophageal toxicity were the most frequent indications for interrupting TRT. Variables including advanced age (>70 years), gender, race, or radiotherapy treatment volume did not predict for TRT interruptions. Overall survival (OS) and local tumor control did not correlate with the administration of TRT interruptions or with TRT duration.

CONCLUSION

Toxicity mandated interruptions of conventional dose, once-daily, TRT may not adversely affect outcomes for patients receiving TRT concurrent with chemotherapy (cycle 4) for LSCLC. The implications for accelerated or high dose TRT regimens are not clear.

Radiotherapy in pediatric medulloblastoma: Quality assessment of Pediatric Oncology Group Trial 9031

PURPOSE

To evaluate the potential influence of radiotherapy quality on survival in high-risk pediatric medulloblastoma patients.

METHODS AND MATERIALS

Trial 9031 of the Pediatric Oncology Group (POG) aimed to study the relative benefit of cisplatin and etoposide randomization of high-risk patients with medulloblastoma to preradiotherapy vs. postradiotherapy treatment. Two-hundred and ten patients were treated according to protocol guidelines and were eligible for the present analysis. Treatment volume (whole brain, spine, posterior fossa, and primary tumor bed) and dose prescription deviations were assessed for each patient. An analysis of first site of failure was undertaken. Event-free and overall survival rates were calculated. A log-rank test was used to determine the significance of potential survival differences between patients with and without major deviations in the radiotherapy procedure.

RESULTS

Of 160 patients who were fully evaluable for all treatment quality parameters, 91 (57%) had 1 or more major deviations in their treatment schedule. Major deviations by treatment site were brain (26%), spinal (7%), posterior fossa (40%), and primary tumor bed (17%). Major treatment volume or total dose deviations did not significantly influence overall and event-free survival.

CONCLUSIONS

Despite major treatment deviations in more than half of fully evaluable patients, underdosage or treatment volume misses were not associated with a worse event-free or overall survival.

High dose fractionated ionizing radiation inhibits prostate cancer cell adhesion and beta(1) integrin expression

BACKGROUND

The effect of ionizing radiation on extracellular matrix (ECM)-mediated cellular functions is an important area of research for translational science. Mechanisms of tumor cell ability to proliferate, migrate, and survive appear dependent on integrin-mediated adhesion to the ECM; however, the exact role therapeutic radiation plays in altering signaling pathways and promoting cell death within remains less well established.

METHODS

To examine these effects on prostate carcinoma cell lines, cells were irradiated at sub-lethal doses. We have studied two human prostate cancer cell lines (PC3 and DU-145) irradiated with different fractionated radiation schedules. Three groups were compared to non-irradiated controls. Group A was given a single dose of 5 Gy. Group B was given 5 Gy the first week and then 10 Gy the second week for a total of 15 Gy. Group C was given 5 Gy the first week, and then 10 Gy the second and third week for a total of 25 Gy. Cells were analyzed at their prescribed total dose. At 48 hr post irradiation, cells were detached from culture dishes and were subsequently used for adhesion assays and immunoblotting analysis.

RESULTS

Our findings revealed that two prostate carcinoma cell lines, PC3 and DU-145, had a reduced cellular adhesion to fibronectin (FN) compared to the non-irradiated control groups. Both prostate cancer cell lines showed decreased adhesion to FN and reduced beta(1) integrin protein levels at a total dose of 25 Gy, but not at the doses of 15 and 5 Gy. In a parallel analysis, at the maximum total dose of 25 Gy, both PC3 and DU-145 demonstrated a significant decrease in cell proliferation.

CONCLUSIONS

High dose radiation treatment of prostate cancer cell lines inhibits integrin expression. Our study suggests that promoting a synergistic decrease in adhesion could bring additional therapeutic benefit to patients treated with radiation therapy.

Analysis of axillary coverage during tangential radiation therapy to the breast

PURPOSE

To evaluate the percent of the prescribed radiation dose to the breast delivered to the axillary tissue and to evaluate the volume of the axilla receiving 95% of the prescribed dose with normal and with high tangential fields.

METHODS AND MATERIALS

Computed tomographic scan images with 5-mm sections were retrospectively analyzed for 35 patients who had undergone three-dimensional (3D) planning for whole-breast radiation. The axillary nodal region was identified and divided into Levels I to III and Rotter's nodes (RN). Digitally reconstructed radiographs were created, and two plans were developed: (a) the standard clinical opposed tangential irradiation fields and (b) the high-tangential irradiation fields. Axillary coverage was examined by use of dose-volume histograms (DVH), and the average coverage for the four nodal groups was obtained.

RESULTS

The data show that with the standard tangential irradiation fields, the average dose delivered to Levels I, II, III, and RN is 66% (standard deviation, or SD = 13%), 44% (SD = 18%), 31% (SD = 20%), and 70% (SD = 19%) of the prescribed dose, respectively. The coverage increases to 86% (SD = 9%), 71% (SD = 19%), 73% (SD = 17%), and 94% (SD = 8%) of the prescribed dose, respectively, for Levels I, II, III, and RN when the high tangential irradiation fields are used. 51% of Level I, 26% of Level II, and 15% of Level III receive 95% of the prescribed dose with normal tangents. The volume increases to 79%, 51%, and 49% of Levels I, II, and III, respectively, with high tangents.

CONCLUSION

The tangential fields designed to treat only the breast do not adequately cover the axillary region and, therefore, cannot be relied upon for prophylactic therapy of the axilla. The high tangential irradiation fields increase the dosages received by the axillary region, but the average dosages received by the lower axillary regions are still less than 90% of the prescribed dose.

An evaluation of the relationship between the quality of prophylactic cranial radiotherapy in childhood acute leukemia and institutional experience: a Quality Assurance Review Center-Pediatric Oncology Group study

PURPOSE

The Pediatric Oncology Group Protocol 9404 was a prospective clinical trial of two forms of chemotherapy in childhood T-cell acute lymphoblastic leukemia and advanced stage T-cell lymphoblastic non-Hodgkin's lymphoma. The protocol called for prophylactic C1 whole brain external beam irradiation, 18 Gy in 2 Gy/fraction for 9 fractions. We hypothesized that a correlation would be found between the number of children irradiated on protocol by an institution and the compliance rate of that institution with radiotherapy quality assurance (QA) guidelines. We also hypothesized that QA compliance would improve as the study progressed.

METHODS AND MATERIALS

We scored the radiation dose as a minor deviation from protocol guidelines if the dose to the prescription point differed from the protocol by 6-10%, and a major deviation if it differed from protocol by > 10%. Treatment volumes were scored as a minor deviation if the margins were less than specified or the fields were excessively large. A major deviation was defined as the transection of a potential leukemia-bearing volume such as would be caused by blocking the cribriform plate, optic nerve, or temporal lobe. When the treating physician submitted a treatment plan and simulator film at the initiation of therapy to the Quality Assurance Review Center (QARC), a rapid turn-around review of the plan and suggestions for improvement was provided. At the end of therapy, all simulator and port films were reviewed at the QARC.

RESULTS

We reviewed the data from 353 patients treated at 73 institutions in the United States, Canada, and Europe. Of these patients, 2% (n = 7) were not assessable for QA because of incomplete information. Minor quality deviations were found in 27.7% of patients (n = 98) and major deviations in 7.9% (n = 28). The frequency of major deviations for institutions placing 1-4 patients on study was 11% vs. 5.5% for institutions placing > or =5 patients (p < 0.09). The frequency of minor deviations was 28.6% for institutions placing 1-4 patients on study vs. 27.1% for institutions placing >5 patients (p not significant). The frequency of major deviations fell over time (1996-1997, 15.5% vs. 1998-2001, 4.7%, p < 0.001). The frequency of minor deviations did not (1996-1997, 29.9% vs. 1998-2001, 26.9%, p not significant).

CONCLUSION

For a relatively simple radiotherapy field, with clearly written protocol guidelines and rapid turn-around corrections from QARC, the rate of minor deviations was no different between institutions placing 1-4 patients on study and those placing > or =5. A trend (p < 0.09) was noted, however, for major deviations to decrease as a function of institutional experience, as well as over time (p < 0.001), supporting the validity of the hypothesis that pediatric clinical experience matters in QA for C1 whole brain leukemia radiotherapy.

Quantitative analysis of thymosin alpha1 in human serum by LC-MS/MS

A high performance liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was developed to measure the thymosin alpha 1 (Talpha1) concentration in human serum. Tá1 in human serum was determined by solid phase extraction and reverse phase LC-MS/MS. The high-performance liquid chromatography (HPLC) system interfaced with the MS/MS system with a Turbo Ion spray interface. Positive ion detection and multiple reaction monitoring (MRM) mode were used for this human serum quantitation. Eight different concentration standards were used to establish the detection range. Six quality control (QC) and 2 matrix blanks were checked by calibration curves performed on the same day. The lower quantitation limit was 0.5 ng/mL Talpha1 in human serum. Calibration curves were established between 0.5 to 100 ng/mL by weighted linear regression. The correlation coefficients for different days were 0.9955 or greater. Quantitation of Talpha1 by the LC-MS/MS method is fast, accurate, and precise.

Intensity modulation for breast treatment using static multi-leaf collimators

PURPOSE

To achieve more uniform dose distributions in breast cancer treatment using multiple sets of multi-leaf collimator (MLC) defined fields. Dose uniformity for many breast cancer patients can be significantly improved by using two or more sets of portals and the "hot" regions of a traditional treatment can be significantly reduced.

METHODS AND MATERIALS

Patients for breast cancer treatment are immobilized with alpha cradle in the traditional arm-up position and have a CT scan in the treatment position. The target volume is delineated on the 5-mm thick CT slices that are obtained from the lower neck to well below the breast target volume. Medial and lateral tangential fields at conventional gantry angles are designed with the aid of digitally reconstructed radiographs (DRRs). The MLC, without collimator rotation, is used to shape the field to spare as much lung as possible. The wedges and relative weights of the beams are optimized to provide the best dose uniformity. For the patients with large dose inhomogeneity, a second set of fields is designed. The weight of the original set of fields is reduced (usually to approximately 90%) so that the "original hot" regions receive the prescription dose; the second set of fields delivers a supplemental dose to the "cold" region, typically approximately 10% of the total dose. The second set of fields has the same beam parameters but "treat" only the part of breast tissue that is "cool." Presently, the design of the reduced field is an iterative process. The process can be extended to more than two sets of portals to obtain the desired dose uniformity.

RESULTS

With 3D planning and multiple MLC fields, dose uniformity in the treatment of breast patients was improved from 7%-22% to approximately 7%-15%. The volume receiving these high doses decreased significantly and shifted from the lung to the target. By keeping the gantry angles and wedges the same for the multiple fields, treatments can be delivered quickly and reliably. The internal mammary nodes (IM) can also be treated without including significant amount of lung or heart in the field.

CONCLUSION

Dose uniformity can be significantly improved by using this intensity modulation technique to treat certain breast patients. With these static MLC fields creating the intensity modulation, the dose uniformity to the breast can be significantly improved and the hot region in lung reduced. There is no increase in setup complexity. The small increase in treatment time is insignificant.

Self-association of the alpha subunit of phosphorylase kinase as determined by two-hybrid screening

The structural organization of the (alphabetagammadelta)(4) phosphorylase kinase complex has been studied using the yeast two-hybrid screen for the purpose of elucidating regions of alpha subunit interactions. By screening a rabbit skeletal muscle cDNA library with residues 1-1059 of the alpha subunit of phosphorylase kinase, we have isolated 16 interacting, independent, yet overlapping transcripts of the alpha subunit containing its C-terminal region. Domain mapping of binary interactions between alpha constructs revealed two regions involved in the self-association of the alpha subunit: residues 833-854, a previously unrecognized leucine zipper, and an unspecified region within residues 1015-1237. The cognate binding partner for the latter domain has been inferred to lie within the stretch from residues 864-1059. Indirect evidence from the literature suggests that the interacting domains contained within the latter two, overlapping regions may be further narrowed to the stretches from 1057 to 1237 and from 864 to 971. Cross-linking of the nonactivated holoenzyme with N-(gamma-maleimidobutyroxy)sulfosuccin-imide ester produced intramolecularly cross-linked alpha-alpha dimers, consistent with portions of two alpha subunits in the holoenyzme being in sufficient proximity to associate. This is the first report to identify potential areas of contact between the alpha subunits of phosphorylase kinase. Additionally, issues regarding the general utility of two-hybrid screening as a method for studying homodimeric interactions are discussed.

Brachytherapy for early endometrial carcinoma: a comparative study with long-term follow-up

The current study was undertaken to evaluate the effect of preoperative uterine or postoperative vaginal brachytherapy compared to no adjuvant therapy on the disease-free interval, sites of recurrence, and survival in favorable stage IB endometrial carcinoma. One hundred and forty-six patients with FIGO grade 1 and 2 endometrial carcinoma and 1-33% myometrial invasion treated between 1974 and 1992 were retrospectively studied. The use of brachytherapy varied among the treating physicians during the study period. A Kaplan-Meier survival analysis was used to estimate disease-free survival and differences between treatment groups were evaluated with the Mantel-Cox statistic. Recurrent disease occurred in 7 patients (5.3%). Vaginal recurrences accounted for 6 of the 7 sites of recurrences. Recurrences occurred in 1.3% of grade 1 vs. 8.7% of grade 2 tumors (P = 0.04). Among 69 grade 2 tumors, recurrences occurred in 7.5% of those treated with brachytherapy vs. 10.3% of those not treated (P = 0.68). Brachytherapy did not affect the disease-free or overall survival. No serious complications directly related to therapy occurred. Vaginal recurrences occur even in early endometrial carcinoma. This study demonstrates no apparent benefit to brachytherapy. A larger study would be required to see a recurrence or survival difference.

Mg2+ induces conformational changes in the catalytic subunit of phosphorylase kinase, whether by itself or as part of the holoenzyme complex

Phosphorylase kinase (PhK) from skeletal muscle is a structurally complex, highly regulated, hexadecameric enzyme of subunit composition (alpha beta gamma delta)4. Previous studies have revealed that the activity of its catalytic gamma subunit is controlled by alterations in quaternary structure initiated at allosteric and covalent modification sites on PhK's three regulatory subunits; however, changes in the conformation of the holoenzyme initiated by the catalytic subunit have been more difficult to document. In this study a monoclonal antibody (mAb gamma79) has been generated against isolated gamma subunit and used as a conformational probe of that subunit. The epitope recognized by this antibody is within the catalytic core of the gamma subunit, between residues 100 and 240, and monovalent fragments of the antibody inhibit the catalytic activity of the holoenzyme, the gamma-calmodulin binary complex, and the free gamma subunit. Activation of PhK by a variety of mechanisms known or thought to act through its regulatory subunits (phosphorylation, ADP binding, or alkaline pH) increased the binding of the holoenzyme to immobilized mAb gamma79, indicating that activation by any of these distinct mechanisms involves repositioning of the portion of the catalytic domain of the gamma subunit containing the epitope for mAb gamma79. The activating ligand Mg2+ also stimulated the binding of the PhK holoenzyme to immobilized mAb gamma79, as well as the binding of mAb gamma79 to immobilized gamma subunit. Thus, Mg2+ increases the accessibility of the mAb gamma79 epitope in both the isolated gamma subunit and in the holoenzyme. Our results suggest that previously reported influences of Mg2+ on the quaternary structure of the PhK holoenzyme are directly mediated by the gamma subunit.

Induction chemotherapy with docetaxel, cisplatin, fluorouracil, and leucovorin for squamous cell carcinoma of the head and neck: a phase I/II trial

PURPOSE

A phase I/II trial of docetaxel, cisplatin, fluorouracil (5-FU), and leucovorin (TPFL5) induction chemotherapy for patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN).

PATIENTS AND METHODS

Twenty-three previously untreated patients with stage III or IV SCCHN and Eastern Cooperative Oncology Group functional status less than or equal to 2 were treated with TPFL5. Postchemotherapy home support included intravenous fluids, prophylactic antibiotics, and granulocyte colony-stimulating factor (G-CSF). Docetaxel dose was escalated to determine the maximum-tolerated dose (MTD). Fifteen patients were treated with three cycles of TPFL5 at MTD. Patients who achieved either a partial response (PR) or complete response (CR) to three cycles of TPFL5 then received definitive twice-daily radiation therapy. Toxicity and clinical and pathologic response to TPFL5 were assessed.

RESULTS

Twenty-three patients received a total of 69 cycles of TPFL5. The MTD was determined to be docetaxel 60 mg/m2. Dose-limiting toxicity (DLT) was neutropenia. Additional significant toxicities at MTD were nausea, mucositis, diarrhea, peripheral neuropathy, and sodium-wasting nephropathy. The overall response rate to TPFL5 was 100%, which included 14 of 23 (61%) clinical CRs and nine of 23 (39%) clinical PRs. Primary-site clinical and pathologic CR rates were 19 of 22 (86%) CRs and 20 of 22 (91%) CRs, respectively. Eight patients had less than a CR in the neck to chemotherapy and, therefore, had postradiation neck dissections, four of which were positive for residual tumor.

CONCLUSION

TPFL5 is a tolerable induction regimen in patients with good performance status. The DLT is neutropenia with significant mucositis, diarrhea, peripheral neuropathy, and sodium-wasting nephropathy. The high response rates to TPFL5 justify further evaluation of this combination of agents in the context of formal clinical trials.

Interactions of a bicyclic analog of colchicine with beta-tubulin isoforms alphabeta(II), alphabeta(III) and alphabeta(IV)

Tubulin exists as various isoforms, which differ in their assembly, drug-binding properties, and the dynamic properties of the microtubules they compose. One of the most striking differences in drug binding among the isoforms is observed with colchicine, which binds much better to the alphabeta(II) and alphabeta(IV) isoforms than to the alphabeta(III) isoform. Here we have studied the interaction of these isoforms with 2-methoxy-5-(2',3',4'-trimethoxyphenyl) tropone (MTPT), an analog of colchicine that lacks the B-ring. The kinetics of association and dissociation were studied fluorometrically, and the kinetic parameters for the two-step binding were determined for different beta-tubulin isoforms. The apparent on-rate constants for alphabeta(II), alphabeta(III) and alphabeta(IV) were 13358, 4558 and 10828 M(-1) s(-1), the off-rate constants (k(-2)) were 0.04, 0.03 and 0.02 s(-1), and the affinity constants are 3.33 x 10(5), 1.56 x 10(5) and 5.44 x 10(5) M(-1), respectively. The differences in kinetic parameters among different beta-tubulin isoforms are greatly reduced when the B-ring is removed. Our results indicate that the B-ring plays a major role in determining the isoform differences, and the results might be of importance for designing tissue-specific analogs of colchicine for cancer chemotherapy.

Pathology of congenital syphilis in rabbits

We have developed a model for congenital syphilis in the rabbit. This report provides additional information on newborn tissue pathology in animals that were infected in utero. A total of 35 pregnancies were evaluated, each containing 6 to 12 newborns. In the infected group, the mortality was approximately 50%; of the live newborns, half appeared normal and half were hyperreflexic, weak, and runty. Gross pathology in the sickly newborns was quite prevalent and involved enlarged spleens with isolated spots of necrosis; enlarged livers that were overtly congested and hemorrhagic and had numerous granular, white spots; and brains with hemorrhage in the occipital area. Histopathology was apparent in different tissues. Lymphocytes, plasma cells, and vacuolated macrophages were prominent in livers, spleens, brains, and bones. A few actively motile treponemes were visualized by dark-field microscopy within extracts of spleen and within cerebrospinal fluid. Low numbers of treponemes were also demonstrated in sections of brain and liver by using the Warthin-Starry silver stain technique. Blood hematocrits were decreased, and extramedullary hematopoiesis was prominent within spleens and livers; this is consistent with anemia. This rabbit model exhibits many of the same pathologic features commonly found in human congenital syphilis.

Primary radiation therapy for endometrial carcinoma: a case controlled study

PURPOSE

Primary radiation therapy is generally considered inferior to a surgical approach for patients with endometrial carcinoma and is reserved for patients with a high operative risk. These patients are usually elderly, have multiple medical problems and frequently die of intercurrent disease. To evaluate the efficacy of primary radiation therapy a case controlled analysis comparing corrected survival of patients treated with primary radiation to patients treated with surgical therapy with or without radiation therapy was performed.

METHODS AND MATERIALS

Sixty-four patients treated with primary radiation therapy were retrospectively studied. A Kaplan-Meier product limit survival analysis was used to estimate survival among patients treated with primary radiation therapy. A case control study matched by clinical stage, tumor grade, and time of diagnosis was performed. The Mantel-Cox statistic was used to evaluated the equality of the survival curves.

RESULTS

Primary radiation therapy was used to treat 9.0% of the patients with endometrial carcinoma during the study period. Cardiovascular disease, diabetes, age greater than 80 and morbid obesity were the most common indications. Ninety percent of patients had either Stage I or II disease. Forty-eight of the 64 patients (75%) completed treatment which included both teletherapy and brachytherapy. Ten patients received brachytherapy only. Twelve complications, both acute and chronic, occurred in eleven patients (17%). Intercurrent disease accounted for 13 of the 36 (36%) of the deaths. Clinical stage of disease and histologic grade of the tumor were significant predictors of survival, p = 0.0001 and p = 0.013, respectively. The case controlled study of Stage I and II patients treated by primary radiation therapy matched to surgically treated controls showed no statistical difference in survival. Dilatation and curettage after the completion of radiation therapy was predictive of local control, p = 0.003.

CONCLUSION

Although surgery followed by tailored radiation therapy has become widely accepted therapy for Stage I and II endometrial carcinoma, even in patients who are a poor operative risk, the survival with primary radiation therapy is not statistically different.

Tolerances in setup and dosimetric errors in the radiation treatment of breast cancer

PURPOSE

Treatment failure in radiation therapy, as well as unexpected complications, can be associated with set up changes or variations that can cause deviations from the prescribed radiation dose distribution both inside and outside the target volume. The effect of various deviations from the planned setup on the delivery of the prescribed radiation dose to the desired treatment volume was studied.

METHODS AND MATERIALS

Adding a second simulation was investigated as means of minimizing setup changes on treatment. The first simulation was used for planning the treatment and the second simulation was essentially a mock treatment. Dosimetric evaluations based on dose volume histograms were analyzed for each deviation in the setup.

RESULTS

In 95% of the patients, the frequency of the changes in the setup parameters between the second simulation and the treatment setup were reduced significantly from the changes that occurred between the first simulation and the second simulation. The changes in isocenter coordinates up to +/- 1.0 cm have minimal effects (+/- 2%) on the dose distributions. Gantry angle variations up to +/- 4 degrees produce a change of less than +/- 5% in the dose distribution within the target volume. However, this angular variation resulted in additional tissue irradiation outside of the desired treatment field (about 10 cm3 for a large patient). A gantry angle variation of +/- 6 degrees can change the volume of tissue that receives the prescribed dose by at least +/- 10%. In addition, such a change can increase the volume of tissue outside the desired treatment field that is irradiated.

CONCLUSION

It is concluded that individually, deviations in one of the parameters from the planned setup of +/- 1.0 cm in isocenter position and +/- 4 degrees in gantry angle do not produce significant deviations from the planned dose distribution. However, a significant change in dose distribution is observed if the setup parameters are concurrently changed. A second simulation may minimize the deviations of the treatment setup from the planned setup and maximize the precision in dose delivery to the target volume.

Evidence for an alternative pathway for colchicine binding to tubulin, based on the binding kinetics of the constituent rings

The kinetics of tropolone methyl ether binding to tubulin were measured by following the loss of colchicine binding capacity upon preincubation of tubulin with tropolone methyl ether. At 25 degrees C a bimolecular association rate constant of 2.7 (+/- 0.2) M-1 min-1 was determined, and from the temperature dependence an activation energy of 37 (+/- 8) kJ.mol-1 was calculated. By displacement experiments a dissociation rate constant of 2.9 (+/- 0.6) x 10(-2) min-1 was determined at 25 degrees C. The effect of 3',4',5'-trimethoxyacetophenone (TMA) is 2-fold. TMA reduces the apparent association rate constant of colchicine, indicating that it equilibrates very rapidly and reversibly with the colchicine binding site. From this reduction the binding constant for TMA can be obtained. At 25 degrees C a value of 112 (+/- 13) M-1 is estimated. The binding of TMA is practically thermoneutral. Preincubation of tubulin with TMA over 30 min not only reduces the subsequent binding rate constant of colchicine but also the amplitude. This indicates that TMA also binds slowly in a second mode or site. Stopped-flow kinetic studies reveal that fast TMA binding competes for the initial binding of colchicine. From these results it is concluded that colchicine binds initially with its trimethoxybenzene ring and in a subsequent step with the tropolone ring.

Rhom-2 expression does not always correlate with abnormalities on chromosome 11 at band p13 in T-cell acute lymphoblastic leukemia

A frequent site for nonrandom recombination in T-cell acute lymphoblastic leukemia (T-ALL) is chromosome 11 at p13. The molecular characterization of a (7;11)(q35;p13) translocation showed that the translocation breakpoint was 2 kb 5' to the T-ALLbcr locus resulting in the juxtaposition of the T-cell receptor (TCR) beta gene to the rhom-2 gene locus. Northern blot analysis did not detect expression of the rhom-2 gene in the leukemic blasts of the (7;11) translocation. However, using a sensitive polymerase chain reaction (PCR)-based assay, the (7;11) translocation showed a trace expression of rhom-2 at a level of 0.01% of TCR-beta message. Because rhom-2 is considered a proto-oncogene, the significance of the trace expression of rhom-2 in the (7;11) translocation was investigated by comparing the level of rhom-2 expression in 7 additional T-ALLs, normal thymocytes, and CEM (pre-T) and HPB (mature-T) cell lines using the PCR assay. The CEM cells, normal thymocytes, and one patient, whose blasts had no cytogenetic abnormality of chromosome 11, did not express rhom-2 indicating that rhom-2 is not normally expressed in T cells. The other six T-ALLs fell into three categories: (1) two T-ALLs overexpressed rhom-2 in the presence of a translocation; (2) two T-ALLs had trace expression in the presence of a translocation; and (3) two T-ALLs had trace expression with no observable abnormalities on chromosome 11 at p13. Therefore, the data indicate that not all translocations at the T-ALLbcr locus result in overexpression of rhom-2. To account for the sharp contrast in rhom-2 expression seen in these T-ALLs, a model is proposed with a negative regulatory element in the T-ALLbcr locus that is disrupted in some of the cases leading to overexpression of rhom-2.

Expression of the V(D)J recombinase gene RAG-1 is tightly regulated and involves both transcriptional and post-transcriptional controls

The V(D)J recombinase activating genes, RAG-1 and RAG-2, are coexpressed only in immature lymphocytes, and are sufficient and necessary for V(D)J recombination to occur in non-lymphoid cells. In order to examine control mechanisms operative in the regulation of RAG-1 and RAG-2, we have studied the pattern of expression of these genes in human pre-T cells, pre-B cells, and thymocytes treated with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA); an agent which mimics some of the lymphocyte maturation changes seen in vivo. The expression of RAG-1 and RAG-2 was tightly controlled in a rapid, yet very complex, manner with both positive and negative control elements operating. Treatment of immature lymphocytes with TPA caused the specific and rapid elimination of steady-state RAG-1 and RAG-2 RNA. Nuclear run-on assays showed that TPA completely repressed the transcription of RAG-1 within 30 min. In addition to repressing the transcription of RAG-1, TPA treatment caused the rapid and specific degradation of RAG-1 transcripts by decreasing the apparent half-life of RAG-1 mRNA more than two-fold. As judged by cycloheximide treatment of cells, the effects of TPA were not dependent on new protein synthesis. A labile transcriptional repressor, separate from the TPA-associated repression of transcription, was also active in cells transcribing RAG-1 and RAG-2 RNA. After depletion of this labile repressor by cycloheximide treatment, steady-state RAG-1 and RAG-2 RNA levels, and their transcription rates, were elevated four- to six-fold; but were still susceptible to elimination by TPA treatment. Treatment of pre-T CEM cells with interleukin-2, or theophylline (an agent that increases intracellular cAMP) resulted in a two-fold increase in RAG-1 RNA suggesting that lymphokines, either independently or through second messengers, may modulate RAG-1 and RAG-2 expression. The complex, rapid and precise regulation of RAG-1 and RAG-2 expression is consistent with the view that it is necessary for the cell to tightly regulate V(D)J recombinase levels; lower expression may result in inefficient recombination of Ig/TCR genes, whereas increased expression may lead to recombination errors that are deleterious to the cell.

MKW, a novel hematopoietic antigen

A novel hematopoietic antigen was identified using a murine monoclonal antibody raised against KG-1 cells. This antigen, termed MKW, was also detected on the surface of the monocytic cell line U937, but not on the K562, ML1, or HL-60 cell lines. On normal hematopoietic cells, the antigen is expressed on the surface of monocytic and myelocytic cells and on a subpopulation of B-cells. During normal hematopoiesis, the surface expression of MKW is greatest and occurs very early on monocytic cells. Alternatively, in myeloid cells, surface expression occurs later and cell maturation is correlated with increased surface expression. When U937 cells are induced to differentiate, surface expression is transiently up-regulated. Surface expression of MKW, however, does not appear to be an activation antigen since activation of purified T- or B-cells failed to increase MKW on the cell surface. Leukemic blasts from 22 of 80 children (27%) with acute myeloblastic leukemia and from 29 of 225 children (13%) with acute lymphoblastic leukemia expressed MKW on the cell surface. Although surface expression of MKW was absent on T-cell lines, peripheral T-cells, and most B-cells, the antigen was identified in the cytoplasm of some B-cells, T-cells, and cell lines. Immunoprecipitation studies showed that MKW is a 52-kDa protein whether expressed on the cell surface or in the cytoplasm, and it appears to be nonglycosylated. Furthermore, studies with phosphatidylinositol-phospholipase C suggested that MKW is not attached to a glycolipid anchor. The biochemical characterization of MKW and its pattern of expression are distinct from any of the previously identified CD groups or published antigens. Since this unique antigen has prognostic significance in leukemia and appears to be associated with cell differentiation, its exact role in hematopoiesis should be investigated.

Brain and egg tubulins from antarctic fishes are functionally and structurally distinct

The multitubulin hypothesis proposes that chemically distinct tubulins may possess different polymerization properties or may form functionally different microtubules. To test this hypothesis, we have examined the functional properties and the structures of singlet-specific nonneural and neural tubulins from Antarctic fishes. Tubulins were purified from eggs of Notothenia coriiceps neglecta, and from brain tissues of N. coriiceps neglecta or N. gibberifrons, by DEAE ion-exchange chromatography and cycles of microtubule assembly/disassembly. At temperatures between 0 and 20 degrees C, each of these tubulins polymerized efficiently in vitro to yield microtubules of normal morphology. Critical concentrations for polymerization of egg tubulin ranged from 0.057 mg/ml at 3 degrees C to 0.002 mg/ml at 18 degrees C, whereas those for brain tubulin at like temperatures were 4-10-fold larger. Polymerization of both tubulins was entropically driven, but the apparent standard enthalpy and entropy changes for microtubule elongation by egg tubulin (delta Happ0 = +33.9 kcal/mol, delta Sapp0 = +151 entropy units) were significantly greater than values observed for brain tubulin (delta Happ0 = +26.5 kcal/mol, delta Sapp0 = +121 entropy units). Egg tubulin was composed of approximately six alpha and two beta chains and lacked the beta III isotype, whereas brain tubulin was more complex (greater than or equal to 10 of each chain type). Furthermore, egg alpha tubulins were more basic, and their carboxyl termini more resistant to cleavage by subtilisin, than were the alpha chains of brain. We conclude that brain and egg tubulins from the Antarctic fishes are functionally distinct in vitro, due either to qualitative or quantitative differences in isotypic composition, to differential posttranslational modification of shared isotypes, or to both.

The Th1/Th2-like switch in syphilitic infection: is it detrimental?

Organisms that cause chronic diseases have evolved mechanisms to evade those immune defenses that resolve the acute stage of infection (10, 12-14, 21, 22, 32, 35, 37, 38, 40, 42, 45-49, 53). Much is to be learned by specifically identifying the mechanisms underlying these evasive strategies. Important new insights will emerge in terms of immunoregulatory pathways. This in turn will facilitate vaccine development. A good example is leishmania infection. The acute stage of this disease is resolved by DTH-macrophage activation. Leishmanial components preferentially activate Th2 lymphocytes. As a consequence, Th1 effects are minimized and infection is exacerbated leading to chronicity (10, 14, 32). To overcome this negative tendency, leishmanial vaccines are administered in combination with exogenous gamma interferon (42). This selects for Th1 predominance and generates protective immunity. Syphilis exhibits many parallels to the other nine chronic diseases mentioned above. Similarities include an acute localized stage that readily heals, early clearance via DTH-macrophage activation, transient concomitant immunity during acute infection, development of macrophage suppression through PGE2 down-regulation, beneficial effects of exogenous gamma interferon, and elements of autoimmunity. Some of the complexities of immunoregulation during treponemal infection have just begun to be unraveled. It will be important to develop further insight into the Th1/Th2 switch especially as it relates to chronicity. Macrophages seem to be intimately involved in the mechanics of this switch, and their specific role needs further clarification. Whatever is learned about syphilis, as well as other chronic infections will contribute to a better understanding of the generalized pathways of immunoregulation.

Effects of cefetamet (Ro 15-8074) on Treponema pallidum and experimental syphilis

Cefetamet pivoxil (Ro 15-8075) is a newly developed, expanded-spectrum cephalosporin that is orally active. In vitro, the active form, cefetamet (Ro 15-8074), at a concentration of 0.05 micrograms/ml killed and lysed Treponema pallidum. Rabbit serum did not diminish its effectiveness. The antibiotic rapidly entered the circulation following intramuscular injection into rabbits, attaining its highest levels of 24 to 37 micrograms/ml within 10 to 30 min. Animals were infected intradermally with T. pallidum and then treated with different doses of cefetamet. Accelerated healing was detected following treatment with 15 and 30 mg/kg of body weight. The antibiotic was also effective in killing organisms that had disseminated to distant tissues. In three separate sets of experiments, rabbits were infected with treponemes and then treated with cefetamet intramuscularly at 1, 15, or 30 mg/kg as follows: (i) after lesions had just become clinically apparent, (ii) after lesions were enlarged and well developed, or (iii) prior to the appearance of clinical lesions. Antibiotic effectiveness was determined by sacrificing the animals 1 week after antibiotic treatment and examining splenic tissue for residual, disseminated treponemes. Cefetamet was treponemicidal in all three situations. Maximum effects occurred when the antibiotic was injected before lesions had become clinically apparent (incubation period). These results suggest that cefetamet pivoxil might be useful for treating syphilitic infections.

Macrophage and lymphocyte functions are down-regulated in newborn rabbits

We have developed an animal model for congenital syphilis. Treponema pallidum is injected intravenously into pregnant rabbits and fetuses are infected in utero. As a prelude to characterizing the immunologic consequences of fetal infection, it was necessary to expand on the baseline information about newborn rabbit immune capabilities. Studies were undertaken to determine splenic macrophage and T lymphocyte functions with emphasis on newer immunologic parameters. Newborns aged 2 weeks were compared to adults. Macrophage capabilities in newborn rabbits differed from those of their adult counterparts. These cells produced similar basal levels of interleukin 1 (IL-1) but failed to respond to the IL-1 stimulants of lipopolysaccharide (LPS) or T. pallidum. Macrophages also exhibited diminished levels of la expression and increased levels of prostaglandin E2 (PGE2) secretion. T lymphocyte functions were altered in newborn spleen preparations. Following concanavalin A (Con A) stimulation, interferon gamma production was half that of adults; in direct contrast, IL-2 production was twice that of adults. Con A-induced lymphocyte proliferation was markedly decreased in newborn preparations. This diminished response resulted from down-regulation rather than immaturity. When newborn splenic cells were stimulated with Con A in the presence of indomethacin, anti-transforming growth factor (anti-TGF), or exogenous IL-1/IL-2, better proliferation resulted. PGE2, which is well established as a down-regulator of newborn immune functions in human and mouse systems, also appears to play a role in suppressing newborn rabbit functions. TGF is a potent suppressor of a number of adult immunologic reactions. This is the first documentation of the potential role of this factor in down-regulating newborn immune capabilities. These findings provide a framework for future investigations of our congenital syphilis model.

c-tal, a helix-loop-helix protein, is juxtaposed to the T-cell receptor-beta chain gene by a reciprocal chromosomal translocation: t(1;7)(p32;q35)

Studies on nonrandom chromosomal translocations have been important for the identification of genes potentially involved in the malignant transformation of cells. The most widely studied translocations, involving members of the Ig supergene family, have shown juxtapositions of proto-oncogenes with the rearranging loci. Such translocations can inappropriately activate expression of the proto-oncogenes and thereby play a role in tumorigenesis. Because the cytogenetic analysis of a bone marrow sample from a child with T-cell acute lymphoblastic leukemia showed a (1;7)(p32;q35) translocation, we sought to determine if the translocation breakpoint was in the T-cell receptor (TCR)-beta gene locus on chromosome 7. Analysis of the TCR-beta gene by Southern blotting showed three rearranged bands. Nucleotide sequencing and Southern blot analysis of TCR-beta genomic clones, isolated from patient DNA, showed that one contained a normal rearrangement of the TCR-beta gene using V beta 12.2, D beta 2.1, and J beta 2.5, whereas two other clones contained DNA from derivative chromosomes 1 and 7. Chromosomal mapping showed that the (1;7) translocation breakpoint was 35 kb 3' to the c-tal gene locus. The juxtaposition of c-tal to the TCR-beta locus may enhance c-tal expression and contribute to T-cell leukemogenesis.

Splenic T-lymphocyte functions during early syphilitic infection are complex

Immune regulation during syphilitic infection is extremely complex. This paper presents findings on the early events of T-cell activation following testicular infection in rabbits. Treponema pallidum was preincubated for 24 h with nonadherent spleen cells. After being washed to remove the organisms, these spleen cells were either stimulated with concanavalin A (ConA) to induce interleukin-2 (IL-2), or added to adherent cells that were then stimulated with lipopolysaccharide to induce IL-1. Preincubation with the treponemes up-regulated nonadherent cell functions. These sensitized cells increased their IL-2 production and augmented macrophage IL-1 synthesis. In sharp contrast, if this preincubation step was omitted, down-regulation was apparent. When T. pallidum was directly incubated with nonadherent cells in the presence of ConA, reduced levels of IL-2 were detected. Nonadherent cells from infected rabbits secreted soluble suppressive factors after 48 h of in vitro incubation; these factors inhibited ConA-induced IL-2 generation as well as ConA-induced lymphocyte proliferation. At least some of this suppressive activity was attributed to transforming growth factor. In addition, when T lymphocytes were depleted, less suppression was detected. Treponemes also inhibited ConA-induced T-cell proliferation, and monophosphoryl lipid A reversed this inhibitory effect. Since monophosphoryl lipid A neutralizes T-suppressor activity, these findings further suggest a role for T-suppressor activity during syphilitic infection. Finally, T. pallidum directly stimulated IL-2 synthesis when coincubated with phorbol myristate acetate. This agent reverses the prostaglandin E2 blockage of T-helper cell protein kinase C, a necessary second messenger signal for IL-2 synthesis. In summary, T-cell functions are extremely complex and represent a composite of both stimulation and down-regulation, which occur concurrently but to different degrees.

Electron beam modifications for the treatment of superficial malignancies

For the treatment of superficial tumors, the surface dose should be high; unfortunately, because of pronounced dose buildup in low energy electron beams, their efficacy for such treatment is reduced. Electron beams can be modified by placing a low atomic number material called a beam spoiler in the beam. In general, the surface dose is a function of electron energy, source to surface distance, field size, thickness of beam spoiler, distance of beam spoiler from surface, atomic number of beam spoiler, and angle of the beam. The effects of these parameters are evaluated with respect to surface dose, bremsstrahlung dose, and field size changes for small fields at standard SSD and electron energies from 6 to 17 MeV. It was found that the use of a beam spoiler can generally increase the surface dose to values exceeding 90% of the maximum buildup value while maintaining a bremsstrahlung dose less than 3%. Changes in field size related to the placement of the beam spoiler were considerable in some cases.

High-dose, short-duration cisplatin/doxorubicin combination chemotherapy for advanced ovarian epithelial cancer

Sixty-one patients with epithelial ovarian cancer were treated with intensive high-dose, short-course chemotherapy that consisted of cisplatin (120 mg/m2) and doxorubicin (70 mg/m2) every 3 weeks for four cycles. Patients in complete clinical remission were offered second-look laparotomy (SLL). Patients with minimal or no residual disease at SLL were randomized to either cyclophosphamide (1000 mg/m2 every 21 days for six cycles) or whole-abdominal radiation therapy. All patients completed therapy with a median leukocyte nadir 1.3/microliter and platelet nadir of 90/microliters. Forty-five patients (74%) had a complete clinical response. Results of twenty-two of 36 second-look procedures (64%) showed no evidence of disease (NED). After SLL, 19 patients received six courses of cyclophosphamide and 16 patients received whole-abdominal radiation. Nine patient who refused SLL and one patient with negative SLL findings refused additional treatment. The median survival time for all patients was 51.3 months. High-dose intensive chemotherapy regimens have high response rates, but survival needs to be compared with traditional low-dose regimens. Although high-dose cisplatin and doxorubicin were myelosuppressive, the resulting complications were manageable. There was no significant difference between the mean survival times of patients receiving Cytoxan, abdominal radiation, or no treatment as second-line therapy.

Detection of minimal residual disease in T-cell acute lymphoblastic leukemia using polymerase chain reaction predicts impending relapse

After achieving remission, approximately one-third of patients with T-cell acute lymphoblastic leukemia (T-ALL) relapse due to the resurgence of residual leukemic cells that cannot be detected in remission by morphologic methods. Thus, the early detection of residual disease is highly desirable to monitor the efficacy of therapy, or to institute an alternative mode of therapy. Toward this aim, we have examined the applicability of polymerase chain reaction (PCR) amplification in the detection of minimal residual disease (MRD) in bone marrow samples from patients with T-ALL in morphologic remission. Two different approaches were taken to identify leukemic clone-specific sequences that could be used as targets for PCR amplification. The first technique used T-cell receptor-delta (TCR-delta) gene rearrangements that were sequenced directly after PCR amplification of leukemic DNA. This method was successful in generating clone-specific probes for 76% of T-ALL patients screened. An alternative method was used to clone and sequence a TCR-beta chain gene from leukemic cells to generate a specific probe. The PCR assays that we used were specific for each patient's leukemic clone, and were capable of routinely detecting one leukemic cell in 10(4) normal cells. Using these sensitive PCR-based assays, we found no evidence for persistence of the leukemic clone in any of the bone marrow samples from four T-ALL patients who are in long-term (3.9 + to 8.1 + years) remission. In contrast, we detected residual disease in clinical remission samples from two patients who subsequently relapsed. In one patient, where we had appropriate samples, we observed a dramatic expansion of the leukemic clone 3 months before clinical relapse. These results suggest that PCR-based assays for detection of MRD in T-ALL patients have great potential in predicting impending relapse, and in determining the efficacy of the anti-leukemic therapy. These methods may also allow the identification of long-term survivors.

Splenic macrophage function in early syphilitic infection is complex. Stimulation versus down-regulation

Macrophages are important regulatory cells that can both stimulate and down-regulate various immune functions. During syphilitic infection, these cells phagocytize, kill, and lyse Treponema pallidum. They also modulate early T cell activation by decreasing IL-2 production through secretion of PG. This report focuses on additional complexities of macrophage regulation. Non-adherent splenic cells were stimulated with Con A to induce IFN-gamma synthesis. High levels were detected in preparations from normal rabbits and much lower levels in preparations from infected rabbits. The organisms also readily stimulated IL-1 synthesis by adherent spleen preparations from normal but not from infected rabbits. When indomethacin was added to these latter preparations, this IL-1 defect was reversed, implicating PG in this down-regulation. Spleen cells were obtained from normal rabbits and from rabbits infected testicularly for 9 to 12 days. Infection elevated basal levels of class II Ia Ag on adherent cells. In addition, macrophage Ia expression was increased during 4 days of in vitro incubation with treponemes. Non-adherent spleen cells from infected animals inhibited two different macrophage functions. First, culture filtrates obtained after 48 h of incubation contained a soluble factor that subsequently decreased LPS-induced IL-1 synthesis. Second, when macrophages were co-incubated with non-adherent cells, treponemal stimulation of macrophage Ia expression was inhibited; this inhibition was reversed by indomethacin implicating prostaglandins in this down-regulation. In further experiments an exogenous source of IFN-gamma was incubated with adherent cells from infected rabbits. This stimulated macrophage function as shown by increased IL-1 synthesis and Ia expression and decreased PGE2 secretion. Results are discussed in terms of the complexities of immunoregulation by macrophages during syphilitic infection.

Splenic macrophage function in early syphilitic infection is complex. Stimulation versus down-regulation

Macrophages are important regulatory cells that can both stimulate and down-regulate various immune functions. During syphilitic infection, these cells phagocytize, kill, and lyse Treponema pallidum. They also modulate early T cell activation by decreasing IL-2 production through secretion of PG. This report focuses on additional complexities of macrophage regulation. Non-adherent splenic cells were stimulated with Con A to induce IFN-gamma synthesis. High levels were detected in preparations from normal rabbits and much lower levels in preparations from infected rabbits. The organisms also readily stimulated IL-1 synthesis by adherent spleen preparations from normal but not from infected rabbits. When indomethacin was added to these latter preparations, this IL-1 defect was reversed, implicating PG in this down-regulation. Spleen cells were obtained from normal rabbits and from rabbits infected testicularly for 9 to 12 days. Infection elevated basal levels of class II Ia Ag on adherent cells. In addition, macrophage Ia expression was increased during 4 days of in vitro incubation with treponemes. Non-adherent spleen cells from infected animals inhibited two different macrophage functions. First, culture filtrates obtained after 48 h of incubation contained a soluble factor that subsequently decreased LPS-induced IL-1 synthesis. Second, when macrophages were co-incubated with non-adherent cells, treponemal stimulation of macrophage Ia expression was inhibited; this inhibition was reversed by indomethacin implicating prostaglandins in this down-regulation. In further experiments an exogenous source of IFN-gamma was incubated with adherent cells from infected rabbits. This stimulated macrophage function as shown by increased IL-1 synthesis and Ia expression and decreased PGE2 secretion. Results are discussed in terms of the complexities of immunoregulation by macrophages during syphilitic infection.

Congenital syphilis in newborn rabbits: immune functions and susceptibility to challenge infection at 2 and 5 weeks of age

Experiments were performed to further elaborate on our congenital syphilis rabbit model. Attempts were made to determine whether in utero exposure to Treponema pallidum would stimulate immune reactivity and whether this activity would, in turn, affect lesion development upon challenge infection. Newborn rabbits aged 2 or 5 weeks were obtained from control does or from does infected intravenously with T. pallidum during pregnancy. Congenitally infected newborns exhibited increased immunologic functions. Concanavalin A-induced T-lymphocyte proliferation was elevated at both 2 and 5 weeks. In addition, macrophage Ia expression and RPR antibody titers were increased at 5 weeks. In separate experiments, newborn rabbits from control does or from does infected during pregnancy were challenged intradermally with viable organisms at either 2 or 5 weeks of age. Subsequent lesion severity was markedly increased in those newborns previously exposed to treponemes in utero. These observations further strengthen our model for congenital transmission of T. pallidum during pregnancy. We propose that at least some of the tissue pathology in syphilitic infection is associated with activated host defenses.

Hemonectin mediates adhesion of engrafted murine progenitors to a clonal bone marrow stromal cell line from Sl/Sld mice

Mutant Sl/Sld mice exhibit decreased marrow hematopoiesis. The defect is known to reside in the marrow microenvironment of these animals, which is reproduced in vitro by primary marrow explants as well as by cloned marrow stromal cell lines. Bone marrow progenitor cells are incapable of adhering to primary Sl/Sld stromal cells or cloned stromal cell lines derived from them to form cobblestone-islands and proliferate. The role of hemonectin, a marrow-specific adhesion protein in the defective hematopoiesis of the Sl/Sld mice, was studied. Indirect immunoperoxidase staining of marrow in situ from Sl/Sld mice showed little specific staining while specific staining was seen in a pericellular distribution in marrow from +/+ mice. Hemonectin expression in several cloned stromal cell lines from Sl/Sld mice was compared by immunoblotting with that in cloned stromal cell lines from normal +/+ littermates. Cell line Sld3, which has the least hematopoiesis supportive capacity in vitro, showed no detectable hemonectin by immunoblotting, while Sld1 and Sld2 showed detectable but greatly reduced amounts compared with normal +/+ 2.4, GBI/6, and D2XRII. Confluent cultures incubated with purified hemonectin and engrafted with enriched progenitors showed a significant increase in the cumulative number of cobbleston-islands and day 14 spleen colony-forming units (CFU-s) forming progenitors (39.15 +/- 3.6/dish; 16.3 +/- 3.1/dish, respectively), compared with untreated Sld3 cultures (cobblestone-islands 8.1 +/- 3.6/dish; CFU-s forming progenitors 8.8 +/- 0.05/dish). Hemonectin-mediated progenitor cell binding to the Sld3 stromal cells was specifically inhibited by antihemonectin but not by preimmune serum. These data support the role of hemonectin in early progenitor-stromal cell interactions.

Syphilis vaccine: up-regulation of immunogenicity by cyclophosphamide, Ribi adjuvant, and indomethacin confers significant protection against challenge infection in rabbits

Many unsuccessful attempts have been made to develop effective vaccines against experimental syphilitic infection. The focus of this report was to evaluate newer approaches to up-regulate immune responses following immunization with Treponema pallidum. Rabbits were injected once on day 0 with heat-inactivated treponemes suspended in the Ribi adjuvant system containing monophosphoryl lipid A (MPL) and trehalose dimycolate; animals were challenged dermally on day 29 with viable organisms. Various up-regulating agents were then tested using this general immunization protocol. When rabbits were pretreated on day -2 with cyclophosphamide (CYC), no protection was apparent. CYC pretreatment exhibited some protection when combined with a daily course of indomethacin on days 29 to 36. When rabbits were injected on day 0, then given a boost of MPL alone on day +2 plus indomethacin on days 29 to 36, minor protection was again apparent. Excellent protection was achieved when the vaccine protocol involved a combination of CYC pretreatment on day -2, an MPL boost on day +2, and indomethacin on days 29 to 36. Ninety-two percent of the subsequent lesions were atypical as indicated by their flat appearance, small size, lack of ulceration, and rapid healing. Importantly, this vaccine regimen also decreased dissemination of T. pallidum to distant tissues. These results suggest a new perspective in understanding immune responses in syphilis. We propose that vaccination, like infection, generates immune down-regulation that counter-balances immune stimulation. THus, effective vaccines will depend on removal and/or neutralization of treponemal components that down-regulate immune reactivity.

Soluble factors from rabbit spleen cells kill and lyse Treponema pallidum in vitro

Antibody and complement immobilize (kill) Treponema pallidum in vitro. Recent evidence also documents immobilization by soluble factors released by activated macrophages and lymphocytes. Immune-mediated lysis of treponemes, however, has not been reported. The findings in this paper focus on apparent treponemal lysis by rabbit splenic cell preparations. Using cells from animals infected testicularly for 9 to 12 days, unfractionated splenic preparations, as well as adherent and nonadherent preparations, killed and lysed T. pallidum. Phagocytosis alone could not explain the detrimental effects of adherent cells. When cytochalasin B was used to block phagocytosis, decreases in treponemal numbers were still detected. In related studies, immune rabbit sera did not enhance treponemicidal activity of the adherent cells. To assess the specificity of these reactions, T. pallidum was incubated with two monocyte-like cell lines (human U937 and mouse P388D1). Neither cell line was detrimental, and treponemal numbers were not lowered. The soluble nature of the treponemicidal factors from adherent and nonadherent preparations was shown by physically separating these cells from the organisms and demonstrating treponemal killing and lysis. In summary, clearance of T. pallidum from infected tissues is probably at least partially attributed to macrophage phagocytosis. Our findings suggest another mechanism involving lytic factors secreted by activated adherent and nonadherent cells.

Study of dose perturbation parameters for eye shielding in megavoltage photon beam therapy

Shielding blocks are frequently used to minimize dose and shield sensitive organs in radiation therapy. The blocks, which are made of high atomic number materials, produce significant dose perturbations in megavoltage photon beams. The effects of these perturbations are studied with special interest in the eye shielding in the treatment of head and neck malignancies. Optimum parameters for the treatment are suggested.