Thermal ablation compared to stereotactic body radiation therapy for hepatocellular carcinoma: A multicenter retrospective comparative study

BACKGROUND AIMS

Early-stage HCC can be treated with thermal ablation or stereotactic body radiation therapy (SBRT). We retrospectively compared local progression, mortality, and toxicity among patients with HCC treated with ablation or SBRT in a multicenter, US cohort.

APPROACH RESULTS

We included adult patients with treatment-naïve HCC lesions without vascular invasion treated with thermal ablation or SBRT per individual physician or institutional preference from January 2012 to December 2018. Outcomes included local progression after a 3-month landmark period assessed at the lesion level and overall survival at the patient level. Inverse probability of treatment weighting was used to account for imbalances in treatment groups. The Cox proportional hazard modeling was used to compare progression and overall survival, and logistic regression was used for toxicity. There were 642 patients with 786 lesions (median size: 2.1 cm) treated with ablation or SBRT. In adjusted analyses, SBRT was associated with a reduced risk of local progression compared to ablation (aHR 0.30, 95% CI: 0.15-0.60). However, SBRT-treated patients had an increased risk of liver dysfunction at 3 months (absolute difference 5.5%, aOR 2.31, 95% CI: 1.13-4.73) and death (aHR 2.04, 95% CI: 1.44-2.88, p < 0.0001).

CONCLUSIONS

In this multicenter study of patients with HCC, SBRT was associated with a lower risk of local progression compared to thermal ablation but higher all-cause mortality. Survival differences may be attributable to residual confounding, patient selection, or downstream treatments. These retrospective real-world data help guide treatment decisions while demonstrating the need for a prospective clinical trial.

Clinical Data Prediction Model to Identify Patients With Early-Stage Pancreatic Cancer

PURPOSE

Pancreatic cancer is an aggressive malignancy with patients often experiencing nonspecific symptoms before diagnosis. This study evaluates a machine learning approach to help identify patients with early-stage pancreatic cancer from clinical data within electronic health records (EHRs).

MATERIALS AND METHODS

From the Optum deidentified EHR data set, we identified early-stage (n = 3,322) and late-stage (n = 25,908) pancreatic cancer cases over 40 years of age diagnosed between 2009 and 2017. Patients with early-stage pancreatic cancer were matched to noncancer controls (1:16 match). We constructed a prediction model using eXtreme Gradient Boosting (XGBoost) to identify early-stage patients on the basis of 18,220 features within the EHR including diagnoses, procedures, information within clinical notes, and medications. Model accuracy was assessed with sensitivity, specificity, positive predictive value, and the area under the curve.

RESULTS

The final predictive model included 582 predictive features from the EHR, including 248 (42.5%) physician note elements, 146 (25.0%) procedure codes, 91 (15.6%) diagnosis codes, 89 (15.3%) medications, and 9 (1.5%) demographic features. The final model area under the curve was 0.84. Choosing a model cut point with a sensitivity of 60% and specificity of 90% would enable early detection of 58% late-stage patients with a median of 24 months before their actual diagnosis.

CONCLUSION

Prediction models using EHR data show promise in the early detection of pancreatic cancer. Although widespread use of this approach on an unselected population would produce high rates of false-positive tests, this technique may be rapidly impactful if deployed among high-risk patients or paired with other imaging or biomarker screening tools.

Phase I Trial of Stereotactic Body Radiation Therapy Dose Escalation in Pancreatic Cancer

PURPOSE

Stereotactic body radiation therapy (SBRT) has demonstrated encouraging local tumor control rates in the treatment of pancreatic cancer, yet we lack prospective clinical trials evaluating dose-escalation strategies among patients treated with 5-fraction SBRT. This phase 1 dose-escalation trial was conducted to determine the maximum tolerated dose of SBRT in patients with pancreatic cancer.

METHODS AND MATERIALS

Thirty patients with pancreatic cancer were enrolled and treated with 40, 45, or 50 Gy SBRT in 5 fractions with doses determined using a time-to-event continual reassessment method trial design. Systemic therapy was permitted before and after SBRT, but not mandated by the study protocol. Toxicity was the primary study endpoint, and any grade ≥3 acute or late toxicity potentially attributable to SBRT was considered a dose-limiting toxicity. Secondary endpoints included local progression, distant progression, and overall survival.

RESULTS

The median follow up from SBRT was 8.9 months (range, 1.7-62.6 months). Nineteen patients (63%) had locally advanced disease, 3 patients (10%) had metastatic disease, and 8 patients (27%) had medically unresectable disease. Three patients (10%) received 40 Gy, 16 patients (53%) received 45 Gy, and 11 patients (37%) received 50 Gy. Seven patients (23%) experienced grade ≤2 acute toxicity, and 2 patients (6.7%) experienced grade 4 to 5 late toxicity, both of which occurred in the 45 Gy group. Median survival time was 17.1 months from the time of diagnosis and 9.8 months from SBRT. The 1-year cumulative incidence of local progression was 14.2% (95% confidence interval, 4.2%-30%).

CONCLUSIONS

This dose-escalation trial evaluated high-dose SBRT delivered in 5 fractions, and overall demonstrated favorable local control and survival, but was associated with nontrivial rates of severe late gastrointestinal toxicity potentially attributable to radiation. Further prospective studies are needed to define the safety and efficacy of high-dose SBRT in patients with pancreatic cancer.

Impact of Radiation on Cardiovascular Outcomes in Older Resectable Esophageal Cancer Patients With Medicare

OBJECTIVES

Preoperative radiotherapy improves outcomes for operable esophageal cancer patients, though the proximity of the heart to the esophagus puts patients at risk of radiation-induced cardiovascular disease. This study characterizes the impact of radiotherapy and different radiation techniques on cardiovascular morbidity among a cohort of esophageal cancer patients.

MATERIALS AND METHODS

We identified 1125 patients aged 65 and older diagnosed between 2000 and 2011 with esophageal cancer who received surgery alone, or surgery preceded by either preoperative chemotherapy or preoperative chemoradiation from the Surveillance Epidemiology and End Results (SEER)-Medicare database. We used Medicare claims to identify severe perioperative and late cardiovascular events. Multivariable logistic regression and Fine-Gray models were used to determine the effect of presurgery treatment on the risk of perioperative and late cardiovascular disease.

RESULTS

Preoperative chemotherapy or chemoradiation did not significantly increase the risk of perioperative cardiovascular complications compared with surgery alone. Patients treated with preoperative chemoradiation had a 36% increased risk of having a late cardiovascular event compared with patients treated with surgery alone (subdistribution hazard ratio [SDHR]: 1.36; P=0.035). There was no significant increase in late cardiovascular events among patients treated with preoperative chemotherapy (SDHR: 1.18; P=0.40). Among patients treated with preoperative chemoradiation, those receiving intensity modulated radiotherapy had a 68% decreased risk of having a late cardiovascular event compared with patients receiving conventional radiation (SDHR: 0.32; P=0.007).

CONCLUSIONS

This study demonstrates an increased risk of cardiovascular complications among operative esophageal cancer patients treated with preoperative chemoradiation, though these risks might be reduced with more cardioprotective radiation techniques such as intensity modulated radiotherapy.

Association Between African American Race and Clinical Outcomes in Men Treated for Low-Risk Prostate Cancer With Active Surveillance

IMPORTANCE

There is concern that African American men with low-risk prostate cancer may harbor more aggressive disease than non-Hispanic White men. Therefore, it is unclear whether active surveillance is a safe option for African American men.

OBJECTIVE

To compare clinical outcomes of African American and non-Hispanic White men with low-risk prostate cancer managed with active surveillance.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study in the US Veterans Health Administration Health Care System of African American and non-Hispanic White men diagnosed with low-risk prostate cancer between January 1, 2001, and December 31, 2015, and managed with active surveillance. The date of final follow-up was March 31, 2020.

EXPOSURES

Active surveillance was defined as no definitive treatment within the first year of diagnosis and at least 1 additional surveillance biopsy.

MAIN OUTCOMES AND MEASURES

Progression to at least intermediate-risk, definitive treatment, metastasis, prostate cancer-specific mortality, and all-cause mortality.

RESULTS

The cohort included 8726 men, including 2280 African American men (26.1%) (median age, 63.2 years) and 6446 non-Hispanic White men (73.9%) (median age, 65.5 years), and the median follow-up was 7.6 years (interquartile range, 5.7-9.9; range, 0.2-19.2). Among African American men and non-Hispanic White men, respectively, the 10-year cumulative incidence of disease progression was 59.9% vs 48.3% (difference, 11.6% [95% CI, 9.2% to 13.9%); P < .001); of receipt of definitive treatment, 54.8% vs 41.4% (difference, 13.4% [95% CI, 11.0% to 15.7%]; P < .001); of metastasis, 1.5% vs 1.4% (difference, 0.1% [95% CI, -0.4% to 0.6%]; P = .49); of prostate cancer-specific mortality, 1.1% vs 1.0% (difference, 0.1% [95% CI, -0.4% to 0.6%]; P = .82); and of all-cause mortality, 22.4% vs 23.5% (difference, 1.1% [95% CI, -0.9% to 3.1%]; P = 0.09).

CONCLUSIONS AND RELEVANCE

In this retrospective cohort study of men with low-risk prostate cancer followed up for a median of 7.6 years, African American men, compared with non-Hispanic White men, had a statistically significant increased 10-year cumulative incidence of disease progression and definitive treatment, but not metastasis or prostate cancer-specific mortality. Longer-term follow-up is needed to better assess the mortality risk.

A Matched Case-Control Analysis of Clinical Outcomes for Patients With Inflammatory Bowel Disease and Rectal Cancer Treated With Pelvic Radiation Therapy

PURPOSE

Inflammatory bowel disease (IBD) is a known risk factor for rectal cancer, and RT is often an important part of therapy for these patients. Previously published studies have raised concerns for increased rates of RT toxicity in patients with IBD. We performed a matched case-control analysis to assess RT-related toxicity in a large sample of U.S. veterans afflicted with IBD and rectal cancer.

METHODS AND MATERIALS

We identified 186 veterans with rectal cancer (71 Patients with IBD treated with RT, 71 matched controls without IBD treated with RT, and 44 nonmatched controls with IBD treated without RT) diagnosed between 2000 and 2015. We analyzed short- and long-term toxicity and mortality in multivariable logistic regression, Fine-Gray, and frailty models, adjusting for potential confounders.

RESULTS

When comparing patients with and without IBD treated with RT there were no differences in RT breaks (adjusted odds ratio [aOR], 1.70; 95% confidence interval [CI], 0.38-4.76; P = .49) or the need for antidiarrheal medication during RT (aOR, 1.53; 95% CI, 0.70-3.35; P = .29). There was a trend toward higher risk of hospital admission during RT for RT + patients with IBD (aOR, 2.69; 95% CI, 0.88-8.22; P = .08). There were higher rates of small bowel obstruction (OR, 15; 95% CI, 1.9-115; P = .009) and a trend toward higher rates of abdominopelvic adhesions (OR, 3.6; 95% CI, 0.98-13; P = .05) in the RT + IBD cohort. However, compared with a nonmatched cohort of patients with IBD treated without RT there were no differences in long-term complications. No differences were found in other acute or long-term toxicities. Rectal cancer-specific mortality appeared similar across all cohorts.

CONCLUSIONS

RT does not appear to increase the rates of acute or long-term toxicity in patients with IBD and should be considered a standard part of therapy when otherwise indicated.

Clinical Impact of Local Progression in Pancreatic Cancer

Background: The high prevalence of distant metastatic disease among patients with pancreatic cancer often draws attention away from the local pancreatic tumor. This study aimed to define the complications and hospitalizations from local versus distant disease progression among a retrospective cohort of patients with pancreatic cancer. Methods: Records of 298 cases of pancreatic cancer treated at a single institution from 2004 through 2015 were retrospectively reviewed, and cancer-related symptoms and complications requiring hospitalization were recorded. Hospitalizations related to pancreatic cancer were attributed to either local or distant progression. Cumulative incidence analyses were used to estimate the incidence of hospitalization, and multivariable Fine-Gray regression models were used to identify factors predictive of hospitalizations. Results: The 1-year cumulative incidences of hospitalization due to local versus distant disease progression were 31% and 24%, respectively. Among 509 recorded hospitalizations, leading local etiologies included cholangitis (10%), biliary obstruction (7%), local procedure complication (7%), and gastrointestinal bleeding (7%). On multivariable analysis, significant predictors of hospitalization from local progression included unresectable disease (subdistribution hazard ratio [SDHR], 2.42; P<.01), black race (SDHR, 3.34; P<.01), younger age (SDHR, 1.02 per year; P=.01), tumor in the pancreatic head (SDHR, 2.19; P<.01), and larger tumor size (SDHR, 1.13 per centimeter; P=.02). Most patients who died in the hospital from pancreatic cancer (56%) were admitted for complications of local disease progression. Conclusions: Patients with pancreatic cancer experience significant complications of local tumor progression. Although distant metastatic progression represents a hallmark of pancreatic cancer, future research should also focus on improving local therapies.

Stroke and thromboembolic events in men with prostate cancer treated with definitive radiation therapy with or without androgen deprivation therapy

BACKGROUND

There is conflicting evidence regarding the association between androgen deprivation therapy (ADT) for prostate cancer (PC) and the risk of developing stroke and thromboembolic events. Our study evaluated the association between ADT use and development of stroke, transient ischemic attack (TIA), deep vein thrombosis (DVT), and pulmonary embolism (PE) in a homogenous group of men with PC treated with definitive radiation therapy (RT) after controlling for multiple sources of confounding.

METHODS

Observational cohort study of patients diagnosed with PC at the US Department of Veterans Affairs between 1 January 2001 and October 31, 2015 and treated with definitive RT. Exposure was initiation of ADT within 1 year of PC diagnosis. Primary outcomes were development of stroke, TIA, DVT, or PE.

RESULTS

44,246 men with median follow-up of 6.8 years. The overall cumulative incidences of stroke, TIA, DVT, and PE at 10 years were 6.0, 3.0, 3.4, and 1.9%, respectively. In the multivariable competing risks model, there was a significant association between ADT and stroke (subdistribution hazard ratio (SHR) = 1.19, 95% CI = 1.09-1.30, p < 0.01), TIA (SHR = 1.24, 95% CI = 1.08-1.41, p < 0.01), and DVT (SHR = 1.18, 95% CI = 1.04-1.34, p < 0.01). ADT was only associated with PE in men receiving ADT for > 1 year (SHR = 1.34, 95% CI = 1.06-1.69, p-value = 0.03).

CONCLUSION

We observed an increase in the risk of stroke, TIA, and DVT in men receiving ADT and an increased risk of PE in men receiving long-term ADT. These results highlight concerns regarding long-term risks of ADT on stroke and thromboembolic events in the treatment of PC.

Infliximab for treatment-refractory transverse myelitis following immune therapy and radiation

BACKGROUND

Neurologic toxicities with immune therapy are rare, but can cause devastating and often permanent injury when they occur. Although there is increasing interest in the potential synergism between immune therapy and radiation, it is possible that such combinations may lead to a greater number or increased severity of immune-related adverse events. We present here a case of extensive and progressive transverse myelitis following combined therapy, which did not improve until treatment with infliximab. This case highlights the unmet need for treatment of adverse events that are refractory to consensus recommendations, and may ultimately require further study and incorporation into future published guidelines.

CASE PRESENTATION

We report a case of a 68-year-old with metastatic melanoma, who developed transverse myelitis in the setting of immune checkpoint blockade and spinal irradiation for vertebral metastases. Despite management according to published consensus guidelines: cessation of immune therapy, high-dose steroids, and plasmapheresis, he continued to deteriorate neurologically, and imaging revealed a progressive and ascending transverse myelitis. The patient was then treated with infliximab, and demonstrated dramatic imaging and modest clinical improvement following the first treatment cycle.

CONCLUSIONS

This is the first report describing the successful use of infliximab in immune therapy and radiation-related transverse myelitis that was not responding to recommended therapy. Evaluation of additional treatment options such as infliximab for high-grade immune-related neurologic toxicities is warranted, and may be needed earlier in the disease process to prevent significant morbidity. The adverse effects of immune therapy when used in combination with radiation also require further investigation.

Three-month posttreatment prostate-specific antigen level as a biomarker of treatment response in patients with intermediate-risk or high-risk prostate cancer treated with androgen deprivation therapy and radiotherapy

BACKGROUND

Prostate-specific antigen (PSA) measurement after definitive radiotherapy (RT) and androgen deprivation therapy for localized prostate cancer has been proposed as an early prognostic biomarker. In the current study, the authors investigated the association between 3-month post-RT PSA level and biochemical progression-free survival (bPFS), prostate cancer-specific survival (PCSS), and overall survival (OS).

METHODS

A total of 5783 patients with intermediate-risk or high-risk localized prostate cancer who were diagnosed between 2000 and 2015 and treated with RT and androgen deprivation therapy were identified from Veterans Affairs data. Patients were divided into groups based on 3-month post-RT PSA values: <0.10 ng/mL, 0.10 to 0.49 ng/mL, and ≥0.50 ng/mL. The effect of the 3-month PSA group on bPFS, PCSS, and OS was evaluated in multivariable Cox models adjusting for potential confounders.

RESULTS

There were 2651 patients with intermediate-risk and 3132 with high-risk disease; approximately 11% had a 3-month PSA level of ≥0.50 ng/mL. A higher 3-month PSA level was found to be strongly associated with each outcome; compared with patients in the group with a 3-month PSA value <0.10 ng/mL, the authors noted greater hazards for the patients with a 3-month PSA value ≥0.50 ng/mL (hazard ratio for bPFS: 5.23; PCSS: 3.97; and OS: 1.50 [P<.001 for all]) and the patients with a 3-month PSA value of 0.10 to 0.49 ng/mL (hazard ratio for bPFS: 2.41 [P<.001]; PCSS: 2.29 [P<.001]; and OS: 1.21 [P = .003]). When analyzed separately, the 3-month PSA level was found to be predictive of OS in the high-risk group (P<.001) but not the intermediate-risk group (P = .21).

CONCLUSIONS

The 3-month post-RT PSA level appears to be a strong prognostic biomarker for bPFS, PCSS, and OS in patients with intermediate-risk and high-risk prostate cancer, particularly those with high-risk disease. The 3-month PSA measurement may augment clinical decision making and holds promise as a potential surrogate endpoint in clinical trials. Cancer 2018;124:2939-47. © 2018 American Cancer Society.

4π plan optimization for cortical-sparing brain radiotherapy

BACKGROUND AND PURPOSE

Incidental irradiation of normal brain tissue during radiotherapy is linked to cognitive decline, and may be mediated by damage to healthy cortex. Non-coplanar techniques may be used for cortical sparing. We compared normal brain sparing and probability of cortical atrophy using 4π radiation therapy planning vs. standard fixed gantry intensity-modulated radiotherapy (IMRT).

MATERIAL AND METHODS

Plans from previously irradiated brain tumor patients ("original IMRT", n = 13) were re-planned to spare cortex using both 4π optimization ("4π") and IMRT optimization ("optimized IMRT"). Homogeneity index (HI), gradient measure, doses to cortex and white matter (excluding tumor), brainstem, optics, and hippocampus were compared with matching PTV coverage. Probability of three grades of post-treatment cortical atrophy was modeled based on previously established dose response curves.

RESULTS

With matching PTV coverage, 4π significantly improved HI by 27% (p = 0.005) and gradient measure by 8% (p = 0.001) compared with optimized IMRT. 4π optimization reduced mean and equivalent uniform doses (EUD) to all standard OARs, with 14-15% reduction in hippocampal EUD (p ≤ 0.003) compared with the other two plans. 4π significantly reduced dose to fractional cortical volumes (V50, V40 and V30) compared with the original IMRT plans, and reduced cortical V30 by 7% (p = 0.008) compared with optimized IMRT. White matter EUD, mean dose, and fractional volumes V50, V40 and V30 were also significantly lower with 4π (p ≤ 0.001). With 4π, probability of grade 1, 2 and 3 cortical atrophy decreased by 12%, 21% and 26% compared with original IMRT and by 8%, 14% and 3% compared with optimized IMRT, respectively (p ≤ 0.001).

CONCLUSIONS

4π radiotherapy significantly improved cortical sparing and reduced doses to standard brain OARs, white matter, and the hippocampus. This was achieved with superior PTV dose homogeneity. Such sparing could reduce the probability of cortical atrophy that may lead to cognitive decline.

Distortion inherent to magnetic resonance imaging can lead to geometric miss in radiosurgery planning

PURPOSE

Anatomic distortion is present in all magnetic resonance imaging (MRI) data because of nonlinearity of gradient fields; it measures up to several millimeters. We evaluated the potential for uncorrected MRI to lead to geometric miss of the target volume in stereotactic radiosurgery (SRS).

METHODS AND MATERIALS

Twenty-eight SRS cases were studied retrospectively. MRI scans were corrected for gradient nonlinearity distortion in 3 dimensions, and gross tumor volumes (GTVs) were contoured. The manufacturer-specified distortion field was then reapplied to GTV masks to allow measurement of GTV displacement in uncorrected images. The uncorrected GTV was used for SRS planning, and the dose received by the true (corrected) GTV was measured.

RESULTS

Median displacement of the GTV resulting from gradient distortion was 1.2 mm (interquartile range, 0.1-2.3 mm), with a minimum of 0 mm and a maximum of 3.9 mm. Eight of the 28 cases met a priori criteria for "geometric miss."

CONCLUSIONS

Although MRI distortion is often subtle on visual inspection, there is a significant clinical impact of this distortion on SRS planning. Distortion-corrected MRI should uniformly be used for intracranial radiosurgery planning because uncorrected MRI can lead to potential geometric miss.

Single-Isocenter Frameless Volumetric Modulated Arc Radiosurgery for Multiple Intracranial Metastases

BACKGROUND

Stereotactic radiosurgery (SRS) is a well-accepted treatment for patients with intracranial metastases, but outcomes with volumetric modulated arc radiosurgery (VMAR) are poorly described.

OBJECTIVE

To report our initial clinical experience applying a novel single-isocenter technique to frameless VMAR for simultaneous treatment of multiple intracranial metastases.

METHODS

We performed a retrospective analysis of 15 patients undergoing frameless VMAR for multiple intracranial metastases using a single, centrally located isocenter in the period 2009 and 2011. Of these, 3 patients were treated for progressive or recurrent intracranial disease. A total of 62 metastases (median, 3 per patient; range, 2-13) were treated to a median dose of 20 Gy (range, 15-30 Gy). Three patients were treated with fractionated SRS. Follow-up including clinical examination and magnetic resonance imaging (MRI) occurred every 3 months.

RESULTS

The median follow-up for all patients was 7.1 months (range, 1.1-24.3), with 11 patients (73.3%) followed until death. For the remaining 4 patients alive at the time of analysis, the median follow-up was 19.6 months (range, 9.2-24.3). Local control at 6 and 12 months was 91.7% (95% confidence interval [CI], 84.6%-100.0%) and 81.5% (95% CI, 67.9%-100.0%), respectively. Regional failure was observed in 9 patients (60.0%), and 7 patients (46.7%) received salvage therapy. Overall survival at 6 months was 60.0% (95% CI, 40.3%-88.2%). Grade 3 or higher treatment-related toxicity was not observed. The median total treatment time was 7.2 minutes (range, 2.8-13.2 minutes).

CONCLUSION

Single-isocenter, frameless VMAR for multiple intracranial metastases is a promising technique that may provide similar clinical outcomes compared with conventional radiosurgery.

Targeting the PI3K/AKT/mTOR pathway in squamous cell carcinoma of the head and neck

Despite recent advances in novel therapies, the prognosis for patients with squamous cell carcinoma of the head and neck (SCCHN) remains poor. Progress in understanding the biology of cancer has led to the development of personalized therapy targeted at blocking defective signaling pathways of cancer cells. These drugs aim to act selectively to reduce the adverse effects associated with systemic therapy. Cetuximab (Erbitux®), an anti-epidermal growth factor receptor gene (EGFR)-targeted agent, is the only approved targeted therapy for patients with SCCHN. However, resistance to EGFR therapy remains a major obstacle to achieving a positive clinical outcome with cetuximab. Other therapies that offer better clinical outcomes in patients with advanced SCCHN are urgently needed. The phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin pathway, which is downstream of EGFR, has also been implicated in SCCHN development and progression, and therefore, targeting this pathway offers another rational treatment approach. This review discusses the potential role of PI3K pathway inhibitors in the treatment of patients with advanced SCCHN, both alone and in combination with other therapies.

Racial disparity in consultation, treatment, and the impact on survival in metastatic colorectal cancer

BACKGROUND

Black patients with metastatic colorectal cancer have inferior survival compared to white patients. The purpose of this study was to examine disparity in specialist consultation and multimodality treatment and the impact that treatment inequality has on survival.

METHODS

We identified 9935 non-Hispanic white and 1281 black patients with stage IV colorectal cancer aged 66 years and older from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. Logistic regression models identified race-based differences in consultation rates and subsequent treatment with surgery, chemotherapy, or radiation. Multivariable Cox regression models identified potential factors that explain race-based survival differences. All statistical tests were two-sided.

RESULTS

Black patients had lower rates of consultation with surgery, medical oncology, and radiation oncology. Among patients seen in consultation, black patients received less surgery directed at the primary tumor, liver- or lung-directed surgery, chemotherapy, and radiotherapy. Unadjusted survival analysis found a 15% higher chance of dying for black patients compared with white patients (hazard ratio [HR] = 1.15; 95% confidence interval (CI) = 1.08 to 1.22; P < .001). Adjustment for patient, tumor, and demographic variables marginally reduced the risk of death (HR = 1.08; 95% CI = 1.01 to 1.15; P = .03). After adjustment for differences in treatment, the increased risk of death for black patients disappeared.

CONCLUSIONS

Our study shows racial disparity in specialist consultation as well as subsequent treatment with multimodality therapy for metastatic colorectal cancer, and it suggests that inferior survival for black patients may stem from this treatment disparity. Further research into the underlying causes of this inequality will improve access to treatment and survival in metastatic colorectal cancer.

Comparison of daily cone-beam computed tomography and kilovoltage planar imaging for target localization in prostate cancer patients following radical prostatectomy

PURPOSE

To review our initial clinical experience with image-guided radiation therapy (IGRT) using cone-beam computed tomography (CBCT) for prostate bed localization in post-radical prostatectomy (RP) patients and to compare shift and acute toxicity results to our previously published IGRT experience with daily kV planar imaging.

METHODS AND MATERIALS

Fifty patients treated with intensity modulated radiation therapy (IMRT) who had image guidance using either CBCT (n = 23) or kV planar imaging (n = 27) following RP were analyzed. Shifts were recorded in anterior-posterior, superior-inferior, and left-right axes. Total error was defined as the shift from initial setup based on skin markings to isocenter. Prostate bed motion (PBM) was defined as the change in prostate bed position relative to bones. Acute toxicity was graded according to the Radiation Therapy Oncology Group morbidity criteria.

RESULTS

Total error (TE) was measured in 752 CBCTs and 725 kV planar image pairs. PBM was measured in 585 CBCTs and 384 kV planar image pairs. The average magnitudes of TE and PBM in the anterior-posterior, superior-inferior, and left-right axes were greater with kV planar imaging compared to CBCT. Frequencies of acute grade 2 gastrointestinal (13% vs 7%, P = .7) and genitourinary (9% vs 11%, P = 1.0) were similar for CBCT and kV planar imaging patients. No toxicities greater than grade 2 were seen.

CONCLUSIONS

These results suggest that although the magnitudes of TE and PBM were larger with kV planar compared to CBCT, the levels of acute toxicity were acceptable and comparable between the two. The reasons for the differences are unclear, but we postulate that discernment of the prostate bed on the CBCT is more difficult. Further investigation is necessary to determine the reason for the shift differences and to evaluate the benefits and risks of CBCT in this setting.

A survey of stereotactic body radiotherapy use in the United States

BACKGROUND

Stereotactic body radiotherapy (SBRT) is a technique used to deliver high, ablative doses of radiation in a limited number of fractions to ≥ 1 extracranial target(s). To the authors' knowledge, the prevalence of SBRT use among radiation oncologists in the United States is unknown.

METHODS

A random sample of 1600 American radiation oncologists was surveyed via e-mail and facsimile (fax) regarding SBRT usage, including year of adoption, motivations, disease sites treated, and common prescriptions used.

RESULTS

Of 1373 contactable physicians, 551 responses (40.1%) were received. The percentage of physicians using SBRT was 63.9% (95% confidence interval, 60%-68%), of whom nearly half adopted it in 2008 or later. The most commonly cited reasons for adopting SBRT were to allow the delivery of higher than conventional radiation doses (90.3%) and to allow retreatment (73.9%) in select patients. Academic physicians were more likely to report research as a motivation for SBRT adoption, whereas physicians in private practice were more likely to list competitive reasons. Among SBRT users, the most common disease sites treated were lung (89.3%), spine (67.5%), and liver (54.5%) tumors. Overall, 76.0% of current SBRT users planned to increase their use, whereas 66.5% of nonusers planned to adopt the technology in the future.

CONCLUSIONS

SBRT has rapidly become a widely adopted treatment approach among American radiation oncologists. Further research and prospective trials are necessary to assess the benefits and risks of this novel technology.

Observed magnetic resonance imaging changes in pediatric patients treated with stereotactic radiosurgery for intracranial tumors

PURPOSE

This study seeks to characterize magnetic resonance imaging (MRI) changes following stereotactic radiosurgery (SRS) of pediatric brain malignancies.

METHODS

Serial MRI evaluations were performed on 21 lesions treated with SRS for either medulloblastoma (n=12), juvenile pilocytic astrocytoma (n=4), ependymoma (n=2), atypical rhabdoid teratoid tumor (n=2), or pineocytoma (n=1). Prescription doses ranged from 14 to 30 Gy in one to five fractions. Tumor response was qualified as complete (CR), partial (PR), stable disease (SD), or progressive disease (PD) according to the RECIST v1.1. Median radiographic follow-up after SRS was 17 months.

RESULTS

A total of 80 follow-up MRI scans were reviewed with a median of eight per patient. During serial MRI evaluation, eight lesions met criteria for PD at a median of 6 months. However, of these, three (37%) represented transient tumor edema with two lesions later developing a CR at a median of 15 months and one persisting as SD at 12 months. The remaining five lesions were true local failures. Of the 13 lesions that did not show evidence of PD, a CR was obtained in 11 lesions at a median of 3 months (range, 2-6), and SD was seen in the remaining two tumors at last follow-up.

CONCLUSION

Lesion enlargement following SRS for pediatric intracranial tumors is common, and a proportion of patients meeting requirements for PD at early radiographic follow-up may later develop complete resolution of their lesions. Physicians should be aware of these radiographic changes to avoid unwarranted medical and surgical interventions.

A survey of image-guided radiation therapy use in the United States

BACKGROUND

Image-guided radiation therapy (IGRT) is a novel array of in-room imaging modalities that are used for tumor localization and patient setup in radiation oncology. The prevalence of IGRT use among US radiation oncologists is unknown.

METHODS

A random sample of 1600 radiation oncologists was surveyed by Internet, e-mail and fax regarding the frequency of IGRT use, clinical applications, and future plans for use. The definition of IGRT included imaging technologies that are used for setup verification or tumor localization during treatment.

RESULTS

Of 1089 evaluable respondents, 393 responses (36.1%) were received. The proportion of radiation oncologists using IGRT was 93.5%. When the use of megavoltage (MV) portal imaging was excluded from the definition of IGRT, the proportion using IGRT was 82.3%. The majority used IGRT rarely (in <25% of their patients; 28.9%) or infrequently (in 25%-50% of their patients; 33.1%). The percentages using ultrasound, video, MV-planar, kilovoltage (kV)-planar, and volumetric technologies were 22.3%, 3.2%, 62.7%, 57.7%, and 58.8%, respectively. Among IGRT users, the most common disease sites treated were genitourinary (91.1%), head and neck (74.2%), central nervous system (71.9%), and lung (66.9%). Overall, 59.1% of IGRT users planned to increase use, and 71.4% of nonusers planned to adopt IGRT in the future.

CONCLUSIONS

IGRT is widely used among radiation oncologists. On the basis of prospective plans of responders, its use is expected to increase. Further research will be required to determine the safety, cost efficacy, and optimal applications of these technologies.

Single-isocenter frameless intensity-modulated stereotactic radiosurgery for simultaneous treatment of multiple brain metastases: clinical experience

PURPOSE

To describe our clinical experience using a unique single-isocenter technique for frameless intensity-modulated stereotactic radiosurgery (IM-SRS) to treat multiple brain metastases.

METHODS AND MATERIALS

Twenty-six patients with a median of 5 metastases (range, 2-13) underwent optically guided frameless IM-SRS using a single, centrally located isocenter. Median prescription dose was 18 Gy (range, 14-25). Follow-up magnetic resonance imaging (MRI) and clinical examination occurred every 2-4 months.

RESULTS

Median follow-up for all patients was 3.3 months (range, 0.2-21.3), with 20 of 26 patients (77%) followed up until their death. For the remaining 6 patients alive at the time of analysis, median follow-up was 14.6 months (range, 9.3-18.0). Total treatment time ranged from 9.0 to 38.9 minutes (median, 21.0). Actuarial 6- and 12-month overall survivals were 50% (95% confidence interval [C.I.], 31-70%) and 38% (95% C.I., 19-56%), respectively. Actuarial 6- and 12-month local control (LC) rates were 97% (95% C.I., 93-100%) and 83% (95% C.I., 71-96%), respectively. Tumors <or=1.5 cm had a better 6-month LC than those >1.5 cm (98% vs. 90%, p = 0.008). New intracranial metastatic disease occurring outside of the treatment volume was observed in 7 patients. Grade >or=3 toxicity occurred in 2 patients (8%).

CONCLUSION

Frameless IM-SRS using a single-isocenter approach for treating multiple intracranial metastases can produce clinical outcomes that compare favorably with those of conventional SRS in a much shorter treatment time (<40 minutes). Given its faster treatment time, this technique is appealing to both patients and personnel in busy clinics.

Utilization of advanced imaging technologies for target delineation in radiation oncology

PURPOSE

The aim of this study was to evaluate the utilization of advanced imaging technologies for target delineation among radiation oncologists in the United States.

METHODS

A random sample of 1,600 radiation oncologists was contacted by Internet, e-mail, and fax and questioned regarding the use of advanced imaging technologies, clinical applications, and future plans for use. Advanced imaging technologies were defined as any of the following that were directly incorporated into radiation therapy planning: MRI, PET, single-photon emission CT, 4-D CT, functional MRI, and MR spectroscopy.

RESULTS

Of 1,089 contactable physicians, 394 (36%) responded. Of respondents, 65% were in private practice and 35% were in academic practice. The proportion using any advanced imaging technology for target delineation was 95%. However, the majority reported only rare (in <25% of their patients; 46.6%) or infrequent (in 25%-50% of their patients; 26.0%) utilization. The most commonly used technologies were 2-[(18)F]fluoro-2-deoxyglucose PET (76%), MRI (72%), and 4-D CT (44%). The most common cancers treated using image-guided target delineation were those of the lung (83%), central nervous system (79%), and head and neck (79%). Among users of advanced imaging technologies, 66% planned to increase use; 30% of nonusers planned to adopt these technologies in the future.

CONCLUSIONS

Advanced imaging technologies are widely used by US radiation oncologists for target delineation. Although the majority of respondents used them in <50% of their patients, the frequency of utilization is expected to increase. Studies determining the optimal application of these technologies in radiation therapy planning are needed.

Toxicity analysis of postoperative image-guided intensity-modulated radiotherapy for prostate cancer

PURPOSE

To report on the acute and late gastrointestinal (GI) and genitourinary (GU) toxicity associated with a unique technique of image-guided radiotherapy (IGRT) in patients undergoing postprostatectomy irradiation.

METHODS AND MATERIALS

Fifty patients were treated with intensity-modulated radiation therapy (IMRT) after radical prostatectomy. Daily image guidance was performed to localize the prostate bed using kilovoltage imaging or cone-beam computed tomography. The median prescription dose was 68 Gy (range, 62-68 Gy). Toxicity was graded every 3 to 6 months according to the Common Terminology Criteria for Adverse Events version 3.0.

RESULTS

The median follow-up was 24 months (range, 13-38 months). Grade 2 acute GI and GU events occurred in 4 patients (8%) and 7 patients (14%), respectively. No Grade 3 or higher acute GI or GU toxicities were observed. Late Grade 2 GI and GU events occurred in 1 patient (2%) and 8 patients (16%), respectively. Only a single (2%) Grade 3 or higher late toxicity was observed.

CONCLUSIONS

Image-guided IMRT in the postprostatectomy setting is associated with a low frequency of acute and late GI/GU toxicity. These results compare more favorably to radiotherapy techniques that do not use in-room image-guidance, suggesting that daily prostate bed localization may reduce the incidence of adverse events in patients undergoing postprostatectomy irradiation.

Optically-guided frameless linac-based radiosurgery for brain metastases: clinical experience

The purpose of this study was to describe our clinical experience using optically-guided linear accelerator (linac)-based frameless stereotactic radiosurgery (SRS) for the treatment of brain metastases. Sixty-five patients (204 lesions) were treated between 2005 and 2008 with frameless SRS using an optically-guided bite-block system. Patients had a median of 2 lesions (range, 1-13). Prescription dose ranged from 14 to 22 Gy (median, 18 Gy) and was given in a single fraction. Clinical and radiographic evaluation occurred every 2-4 months following treatment. At a median follow-up of 6.2 months, actuarial survival at 12 months was 40% [95% confidence interval (CI), 28-52). Of 135 lesions that were evaluable for local control (LC), 119 lesions (88%) did not show evidence of progression. Actuarial 12 month LC was 76% (95% CI, 66-86). Tumors <or=2 cm in size had a better 12 month LC rate (81% vs. 36%, P = 0.017) than those >2 cm. Adverse events occurred in three patients (5%). Optically-guided linac-based frameless SRS can produce clinical outcomes that compare favorably to frame-based techniques. As this technique is convenient to use and allows for the uncomplicated delivery of hypofractionated radiotherapy, frameless SRS will likely have an increasingly important role in the management of brain metastases.

In situ biosurfactant production by Bacillus strains injected into a limestone petroleum reservoir

Biosurfactant-mediated oil recovery may be an economic approach for recovery of significant amounts of oil entrapped in reservoirs, but evidence that biosurfactants can be produced in situ at concentrations needed to mobilize oil is lacking. We tested whether two Bacillus strains that produce lipopeptide biosurfactants can metabolize and produce their biosurfactants in an oil reservoir. Five wells that produce from the same Viola limestone formation were used. Two wells received an inoculum (a mixture of Bacillus strain RS-1 and Bacillus subtilis subsp. spizizenii NRRL B-23049) and nutrients (glucose, sodium nitrate, and trace metals), two wells received just nutrients, and one well received only formation water. Results showed in situ metabolism and biosurfactant production. The average concentration of lipopeptide biosurfactant in the produced fluids of the inoculated wells was about 90 mg/liter. This concentration is approximately nine times the minimum concentration required to mobilize entrapped oil from sandstone cores. Carbon dioxide, acetate, lactate, ethanol, and 2,3-butanediol were detected in the produced fluids of the inoculated wells. Only CO(2) and ethanol were detected in the produced fluids of the nutrient-only-treated wells. Microbiological and molecular data showed that the microorganisms injected into the formation were retrieved in the produced fluids of the inoculated wells. We provide essential data for modeling microbial oil recovery processes in situ, including growth rates (0.06 +/- 0.01 h(-1)), carbon balances (107% +/- 34%), biosurfactant production rates (0.02 +/- 0.001 h(-1)), and biosurfactant yields (0.015 +/- 0.001 mol biosurfactant/mol glucose). The data demonstrate the technical feasibility of microbial processes for oil recovery.

Nerve growth factor promotes survival of new neurons in the adult hippocampus

Exogenously provided NGF enhances cognitive performance in impaired rodents and humans and is currently a promising compound for the treatment of dementia. To investigate whether NGF-dependent cognitive improvement may be due in part to increased hippocampal neurogenesis, adult and aged male rats were treated with NGF or vehicle intracerebroventricularly for 6 or 20 days followed by evaluation of cholinergic parameters and hippocampal neurogenesis. We show that NGF increases hippocampal cholinergic activity as rapidly as 3 days after initiation of treatment. NGF treatment for 6 days did not affect proliferation of progenitor cells in the dentate gyrus granule cell layer (GCL). However, continuous NGF infusion enhanced survival of new neurons in the GCL of young adult, but not aged rats. Taken together, these findings suggest that NGF, likely mediated through increased cholinergic tone, promotes neurogenesis in the adult hippocampus, which may relate to the nootropic action of NGF.

The relationship of inflammation in the papanicolaou smear to Chlamydia trachomatis infection in a high-risk population

Chlamydia trachomatis is a significant etiologic agent responsible for pelvic inflammatory disease leading to tubal infertility. A screening test aimed at identifying women at risk for Chlamydia trachomatis would be of great utility. The Papanicolaou smear is the most widely used screening test in the world. The association of inflammatory cells in the Papanicolaou smear to Chlamydia infection is controversial. We retrospectively examined the Papanicolaou smears of 80 Chlamydia-negative patients with 80 age-matched Chlamydia-positive patients in a high-risk population to see if a significant difference in inflammation was noted between the two groups. We found a statistically significant difference in inflammation scores between the Chlamydia-positive and Chlamydia-negative groups, evidenced by a sensitivity of 83% and a positive predictive value of 65% when using inflammation on Papanicolaou smears as a marker for Chlamydia infection. Grading of inflammation in the Papanicolaou smear can be of potential use in defining patients at highest risk for Chlamydia in a group considered to be at high risk based on sexual history.

High incidence of extramedullary relapse of AML after busulfan/cyclophosphamide conditioning and allogeneic stem cell transplantation

While allogeneic stem cell transplantation (SCT) is curative for a significant number of patients with AML, relapse of disease within the bone marrow and/or extramedullary (EM) sites following high-dose therapy continues to limit the success of this treatment. Between October 1985 and December 1996, 81 adults underwent allogeneic SCT for de novo AML at our centre. Forty-two patients remain alive and free of leukaemia with a median follow-up of 50 months. The 5-year actuarial event-free survivals (EFS) for all patients and for those undergoing SCT in CR1 or with advanced disease were 46% (95% confidence interval (CI) 34-58%), 63% (CI 46-76%), and 19% (CI 7-36%), respectively. Twenty-two patients relapsed at a median of 8 (range 1.6-54.5) months with the actuarial risk of relapse for all, CR1 and advanced disease patients being 38%, (CI 27-52%), 23% (CI 13-40%) and 68% (CI 46-88%), respectively. Ten patients relapsed at EM sites; six of these (27% of relapses) had an isolated EM relapse at a median of 31 (range 8.5-54) months. Three of the patients with isolated EM relapse survived > or =24 months following relapse and two patients remain disease-free at 29+ and 33+ months. BuCy conditioning followed by allogeneic SCT in AML results in satisfactory EFS although there is a significant risk of late isolated EM relapse.

Successful treatment of veno-occlusive disease with recombinant tissue plasminogen activator in a patient requiring peritoneal dialysis

There have been encouraging reports of the use of recombinant tissue plasminogen activator (tPA) in established veno-occlusive disease (VOD). Haemodialysis has been considered a contraindication to this therapy in view of the potential haemostatic complications. We report a case of a woman who developed moderately severe VOD complicated by anuria following an allogeneic bone marrow transplant for relapsed acute myeloid leukaemia. Following initiation of peritoneal dialysis she received tPA at a dose of 10 mg/day for 5 days. There was rapid improvement in her urine output and liver function with no bleeding complications. This case suggests that the requirement of dialysis may not preclude the use of tPA in established VOD and therefore warrants further study.

Time of nitrogen application and yield of Bengal lychee on a sandy loam soil in subtropical Queensland

Nitrogen (N) was applied over 4 years to 6-year-old lychee trees (Litchi chinensis Sonn. cv. Bengal) growing in subtropical Queensland (lat. 27�S.) on a sandy loam soil (0-15 cm) with 2.8 mg nitrate-N/kg, to determine the effect of time of N application on leaf N concentration, vegetative growth, flowering, and yield. Applications of N (equivalent to 750 kg N/ha in year 4) were made after panicle emergence in July, after harvest in January, or split between the 2 periods. Control trees received no N. Leaf N concentrations in April-June were, on average, about 0.1% lower after a single N application in winter than application in summer or split applications. Leaf N concentrations in November-February were about 0.1% higher after winter or split N applications than after summer applications. Timing of fertiliser application had no affect on yield. It took 4 years without N fertiliser to show significant reductions in yield compared with fertilised trees. In year 4, yield increased from 20 to 60 kg/tree on individual pairs of trees as leaf N in August increased from 0.95 to 1.56%. Lower yields in control trees in year 4 were associated with poor leaf growth in the previous 2 years, and with lower concentrations of N in the panicles, leaves, twigs, and small branches, as well as lower chlorophyll concentrations and net CO2 assimilation after fruit set, compared with trees receiving N.

Effect of paclobutrazol on growth and flowering of lychee (Litchi chinensis)

The effects of either foliar (1.00-4.00 g/L) or soil applications (0.25-1.00 g/m2 tree ground cover) of paclobutrazol, during autumn, on vegetative flushing and flowering of 3 lychee (Litchi chiriensis) cultivars (Bengal, Kwai May Pink and Tai So) were investigated over 3 years at 8 sites in subtropical southern Queensland. Cultivars at these sites varied in the level of vegetative flushing prior to panicle emergence in May-August and flowering in spring. Paclobutrazol reduced flushing and increased flowering in 5 out of 8 orchards, maintained dormancy and reduced flowering in 1 orchard, and had variable effects in 2 orchards, depending on the method of application. The maximum level of flowering in paclobutrazol treated trees occurred when the control trees bloomed moderately (40-60% of terminal branches). The responses were sometimes weak when the trees were very vigorous (<30% bloom). Paclobutrazol had no significant effect or reduced flowering of heavily blooming (70-100% bloom) trees. Paclobutrazol had only a small effect on panicle development, fruit set and fruit quality at most sites. Yield reflected the flowering response to paclobutrazol, except when yields were lowered by excessive male flowering or bird damage to the fruit.

Effect of cincturing on growth and flowering of lychee over several seasons in subtropical Queensland

The effects of autumn cincturing on vegetative flushing and incidence of flowering of 2 lychee (Litchi chinensis) cultivars (Bengal and Tai So) were investigated over 1-3 years at 8 sites in subtropical southern Queensland. Cultivars at these sites varied in the level of natural vegetative dormancy in winter (3-100% of terminal branches) and flowering in spring (0- 100% of terminal branches). There was a strong correlation between percentage flowering (y) and the level of dormancy (x) in the 1-2 months prior to floral initiation (y= 8.8 + 0.83~; r=0.89, P<.001). Cincturing increased flowering by 40-800% in trees that would have flowered poorly in spring (< 70�/o), but had no significant effect (P> 0.05) on flowering in trees that would have bloomed profusely (70-100%), provided trees were adequately fertilised and actively flushing after harvest. This was shown by the relationship, y= 899 - 23.0x+ 0.14x2; r= -0.96, P<0.001), where y is the percentage change in flowering after cincturing and x is the percentage flowering in control trees. Cincturing reduced or delayed flowering if nutrition was not maintained. It is concluded that trees to be cinctured should be adequately fertilised and complete a significant vegetative flush after harvest.

Architectural design and fiber-type distribution of the major elbow flexors and extensors of the monkey (cynomolgus)

Because the architectural and biochemical properties of skeletal muscle dictate its force, velocity, and displacement properties, the major extensors (triceps brachii) and flexors (biceps brachii, brachialis, and brachioradialis) of the elbow in a primate (cynomolgus, monkey) were studied. Functional cross-sectional areas (CSA) were calculated from muscle mass, mean fiber length (normalized to a 2.20 microns sarcomere length), and angle of fiber pinnation measurements from each muscle. Fiber-type distributions were determined and used as a gross index of the biochemical capacities of the muscle. The extensor group had a shorter mean fiber length (31 vs. 47 mm), a larger CSA (13 vs. 8 cm2), and a higher overall percentage of slow-twitch fibers (47 vs. 26%). Consequently, the elbow extensors had a relatively greater potential for force production and force maintenance than the flexors. In contrast, the flexors were designed to optimize their length-velocity potentials; i.e., they had relatively long fibers and a higher fast-twitch fiber composition than the extensors. These morphologic differences between antagonistic muscle groups should be considered when evaluating the motor control mechanisms regulating reciprocal movements about the elbow.

Architectural and histochemical analysis of the semitendinosus muscle in mice, rats, guinea pigs, and rabbits

The architectural and histochemical properties of the anatomically distinct compartments of the semitendinosus muscle (ST) of mice, rats, guinea pigs, and rabbits show that the ST is composed of two separate compartments aligned in series--a distal compartment (STd) and a proximal one (STp). The STp is further subdivided into a ventral head (STpv) and a dorsal head (STpd). The muscle fibers were arranged in parallel to the line of muscle pull within each compartment. The STd has the longest and the STpv the shortest fibers in all species. The physiological cross-sectional area and the estimated tetanic tension was greatest in the STd. Based on the staining pattern for myosin ATPase (alkaline preincubation) and an oxidative indicator (NADH or SDH), the STpv has the highest percentage of slow-oxidative (SO) or SO plus fast-oxidative-glycolytic (FOG) fibers of any portion of the muscle. The differences in fiber-type distributions and architectural designs of the separate compartments suggest a specialization of function of the individual compartments.

Characteristics of blood gas in response to iron treatment and exercise in iron-deficient and anemic subjects

The effects of iron deficiency anemia and iron treatment on blood gas and acid-base balance at rest and during exercise were studied. Eight Sri Lankan males and 13 females were randomly divided into an iron treatment or placebo group. Their initial hemoglobin (Hb) levels were 6.2 +/- 0.5 and 5.5 +/- 0.7 g/100 ml (mean +/- SEM) with serum iron levels of 41 +/- 8 and 30 +/- 6 micrograms/100 ml, respectively. Hemoglobin concentration was increased significantly within 7 days after iron treatment to 7.2 +/- 0.4 g/100 ml. Resting lactate was higher than normal, while base excess, buffer base, and actual bicarbonate were lower, maintaining a normal pH. Heart rates during exercise at a given work load and lactate production following exercise decreased after the elevation of Hb. Venous blood PCO2 rose as Hb concentration increased, preceding a significant increase in resting O2 content, 16 days after iron treatment. With anemia, O2 delivery is potentially maintained by a shift of the O2-dissociation curve to the right due, in part, to 2,3-diphosphoglycerate. There was no significant change in PO2 or Hb-O2% saturation following exercise or iron treatment. These data suggest that severe iron deficiency anemia results in lactate accumulation in blood even at rest but pH is maintained within normal limits. It was also suggested that severe anemia may impair CO2 transport capacity of blood which could limit continuation of muscle metabolism.

External scintigraphy in monitoring the behavior of pharmaceutical formulations in vivo I: technique for acquiring high-resolution images of tablets

A new method for monitoring tablet disintegration in vivo was developed. In this method, the tablets were labeled with a short-lived radionuclide, technetium 99m, and monitored by a gamma camera. Several innovations were introduced with this method. First, computer reconstruction algorithms were used to enhance the scintigraphic images of the disintegrating tablet in vivo. Second, the use of a four-pinhole collimator to acquire multiple views of the tablet resulted in high count rates and reduced acquisition times of the scintigraphic images. Third, the magnification of the scintigraphic images achieved by pinhole collimation led to significant improvement in resolution. Fourth, the radioinuclide was incorporated into the granulation so that the whole mass of the tablet was uniformly labeled with high levels of activity. This technique allowed the continuous monitoring of the disintegration process of tablets in vivo in experimental animals. Multiple pinhole collimation and the labeling process permitted the acquisition of quality scintigraphic images of the labeled tablet every 30 sec. The resolution of the method was tested in vitro and in vivo.

Glucocorticoid-induced atrophy in different fibre types of selected rat jaw and hind-limb muscles

Six weeks of glucocorticoid treatment (triamcinolone-acetonide-21-phosphate, 1 mg/kg of body weight daily) resulted in a similar pattern of fibre type atrophy in jaw and hind-limb muscles. Fast-twitch glycolytic fibres were significantly atrophied in all muscles investigated. Fast-twitch oxidative glycolytic fibres were affected only in the fast (white) regions of the mixed muscles, while slow-twitch oxidative fibres were unaffected. The results from pair-fed controls (food intake matched to the glucocorticoid-treated animals) showed that the glucocorticoid produced an atrophic response in addition to that produced by the decreased food intake in the experimental animals. These results suggest that the jaw musculature shares the wasting effects induced by elevated circulating glucocorticoid levels often found in stress situations.

Changes in work tolerance associated with metabolic and physiological adjustment to moderate and severe iron deficiency anemia

The time course of metabolic and physiological adjustment to moderate iron deficiency anemia (MIDA, 8 g Hb/dl) and to severe iron deficiency anemia (SIDA, 4 g Hb/dl) was studied in adult, male Sprague-Dawley rats at 3, 7, 14, 30, 60, 90, 150, and 360 days, respectively. Our previous studies using the same rats used in the present study indicated that bone marrow iron was absent and plasma iron was significantly lower (p less than 0.001) in MIDA and SIDA relative to control. The following results with MIDA and SIDA rats are all expressed relative to control values. Red cell 2,3-diphosphoglycerate ranged from 45 to 146% greater in MIDA over the 360-day period and was 130% greater in SIDA at 30 days. Exhaustive run time consistently averaged 64 +/- 3% (SEM) less in MIDA over the time course and was further lowered to 18% in SIDA at 30 days. Heart rates of MIDA were elevated (p less than 0.05) at 180 days but lower (p less than 0.001) at 360 days in response to exercise. Resting heart rates of MIDA were the same at 180 and 360 days. Heart rates of SIDA were elevated (p less than 0.05) at rest and during exercise at 30 days. Organ weight/body weight changes indicated cardiomegaly in MIDA from 90 to 150 days which reverted to normal at 360 days; splenomegaly in MIDA from 90 to 360 days; and kidney atrophy in MIDA at 60 and 90 days which reverted to normal thereafter; in SIDA cardiomegaly and splenomegaly were present at 30 days. These results indicate that the onset and magnitude of physiological and metabolic adjustments occur in proportion to the severity of the anemia, and despite compensatory adjustments in parameters related to work performance, a new stable, lowered level of work tolerance is reached.

Evidence for a direct action of thyroid hormone in specifying muscle properties

Thyroidal trophic effects on slow-twitch skeletal muscle properties were compared in normally innervated and denervated soleus of rats maintained at different thyroid states. Hypothyroidism caused fast to slow changes in fiber type composition (99% decrease in proportion of type II fibers), ATPase activities (down 20-30%), myosin light chain pattern (54% less fast light chains), calcium uptake by SR (down 60%), LDH activity (down 11%), and isozyme pattern (9% decrease in M-subunits). Changes of similar magnitude but opposite in direction were induced by thyrotoxicosis. Denervations reversed, to varying degrees, the fast to slow transformations observed in hypothyroidism. However the slow to fast changes found in hyperthyroidism were facilitated rather than inhibited by denervation. These latter results clearly show that the hormone effect can be elicited in the absence of motor innervation. Furthermore, denervation alone caused slow to fast changes in euthyroid muscles. From these results, it is proposed that denervation and dysthyreosis alter muscle properties by independent mechanisms. Our data favor a direct action of thyroid hormone over a neurally mediated mechanism.

The ratio of 3-hydroxyacyl-CoA dehydrogenase to lipoamide dehydrogenase activity in individual muscle fibers: mitochondrial specialization for source of energy

3-Hydroxyacyl-CoA dehydrogenase (HAD) has been widely used to assess the capacity for fatty acid oxidation by different muscle fiber types, with various Krebs cycle enzymes as a base for comparison. We have measured this enzyme in individual lyophilized fibers of the guinea pig soleus and the white and red portions of the vastus lateralis, and compared its activity in each fiber with that of lipoamide dehydrogenase (LAD), which as a part of the pyruvate dehydrogenase complex fulfills a function similar to HAD in forming acetyl-CoA, but from pyruvate and, thus, mainly from a carbohydrate source. The mean HAD/LAD ratio was 17.2 +/- 3 in the red vastus, 24.9 +/- 3 in the white vastus, and 43.7 +/- 10 in the soleus, all differences being highly significant. The two types of fast fibers were not distinguished from one another by the enzyme ratio within either the white or the red portion of the vastus lateralis. Data from all of the fast fibers taken together indicate a close correlation (0.93) between the two enzymes, whereas values from the soleus indicate a specialization of the mitochondria of the slow muscle fibers for the oxidation of fatty acids.

Responses of leukocytes and other hematologic parameters to thermal dehydration

Effects of thermal dehydration without exercise on leukocyte differentials, serum protein fractions, and other hematologic characteristics were studied in six healthy subjects. Both leukocyte and serum total protein levels increased beyond that predicted by hemoconcentration alone. Eosinophil counts decreased significantly, although other leukocyte counts tended to increase. Serum globulin concentrations tended to increase, but the albumin level did not change. Serum K+ concentration was elevated, but Na+ and Cl- were unaffected. It is suggested that thermal dehydration affects blood leukocyte composition and protein metabolism in many of the same ways as physical exercise.

Effects of a mild weight-lifting program on the progress of glucocorticoid-induced atrophy in rat hindlimb muscles

The effect of a mild weight-lifting program on the progress of glucocorticoid-induced atrophy was investigated. Groups of rats were either injected daily for 6 weeks with triamcinolone acetonide, 1 mg/kg (group S), subjected to a weight-lifting program 4 times per week (group T), or subjected to the injection and weight-lifting programs concurrently (group ST). The training program, besides decreasing the normal body weight gain of control (group C) rats, had no effects on gastrocnemius and soleus muscles. In group ST, the extent of gastrocnemius atrophy was less severe than in group S, and the mean areas of all fiber types were greater in similar proportion. Gastrocnemius muscles were also tetanically stronger (g, g/g body weight) in group ST than group S. The soleus muscles of groups ST and S were similar in all indices of size and strength, except for a significantly decreased fast-twitsch-oxidative-glycolytic (FOG) mean fiber area in the ST seleus muscles. The extent of fast-twitsch muscle atrophy resulting from chronic glucocorticoid treatment can be lessened by mild weight-lifting exercise. Differences in fiber area responses between soleus and gastrocnemius may reflect recruitment and/or metabolic differences of similar fiber types in the two muscles.