The role of schools in children's physical activity participation: staff perceptions

The school setting provides a promising environment to increase children's physical activity (PA), however, staff often impact the success of PA within schools. The purpose of this article was to describe the knowledge of elementary school staff related to PA and their perception of the importance of the school environment being conducive to PA prior to the implementation of a recess intervention. Qualitative focus groups were conducted in 12 elementary schools in the Midwest. Grounded theory was used to explore participants' knowledge and perceptions. Participants felt PA was important but believed several factors impacted children's ability to be more active: (i) lack of time due to increasing academic demands, (ii) peer pressure (especially in girls) not to be active and (iii) lack of space and equipment. When discussing recess, staff felt that their encouragement of or active participation in PA with children resulted in more activity. Furthermore, even though participants were aware of PA benefits, they noticed eliminating recess was often used as a punishment for misbehavior. School-based PA promotion and PA opportunities hold great promise for increasing PA in children. However, to maximize these efforts school polices related to training staff about PA are needed.

131I-Metaiodobenzylguanidine (131I-MIBG) double infusion with autologous stem cell transplant for neuroblastoma: A New Approaches to Neuroblastoma Therapy (NANT) study

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Background: 131I-MIBG provides targeted radiotherapy with >30% response in refractory neuroblastoma, but the activity infused is limited by radiation safety and hematologic toxicity. The goal was to determine the maximum tolerated dose of 131I-MIBG in two consecutive infusions at a 2-week interval, supported by autologous stem cell transplant (ASCT) 2 weeks after the second dose. Methods: The 131I-MIBG was escalated in a 3+3 Phase I trial design, with levels calculated by total red marrow radiation index (RMI) from the double infusion. The first infusion of 131I-MIBG was 12, 15, 18 and 21 mCi/kg for levels 1, 2, 3 and 4 respectively. Using detailed dosimetry, the second infusion was adjusted to achieve the target RMI, except at Level 4, where the second infusion was capped at 21 mCi/kg. Results: Twenty-one patients were enrolled at Level 1–4, with 18 evaluable for toxicity. Median age at enrollment was 7 years, all were heavily pretreated, including 12 with prior high dose therapy and ASCT, and 12 patients had bone marrow tumor. Cumulative 131I-MIBG given to achieve the target RMI ranged from 18 mci/kg to 49 mCi/kg. RMI delivered per mCi of MIBG decreased in 15/19 patients by mean of 0.21 cGy/mCi with the second infusion. Hematologic toxicity was acceptable, with median time to ANC>500 after ASCT of 13 (4–27) days. Platelet transfusion was required in 15/18 patients, with median time to platelet independence of 18 (6–47) days after ASCT. There were no non-hematologic toxicities above grade 2 attributed to therapy, though 9 patients had grade 1–2 elevations of transaminase, and 1 had grade 2 hypothyroidism. Responses in 17 evaluable patients included 1 PR, 4 MR, 6 SD, and 6 PD. Eleven patients are alive at median of 361 days (46–483); 5 died of PD and 1 of unrelated toxicity. Conclusion: The lack of toxicity with this approach allowed dramatic dose intensification of 131I-MIBG, with minimal toxicity and the possibility of improved response.

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No significant financial relationships to disclose.

Correlation of tumor and whole-body dosimetry with tumor response and toxicity in refractory neuroblastoma treated with (131)I-MIBG

The purpose of our study was to determine the effect of tumor-targeted radiation in neuroblastoma by correlating administered (131)I-metaiodobenzylguanidine (MIBG) activity to tumor and whole-body dosimetry, tumor volume change, overall response, and hematologic toxicity.

METHODS

Eligible patients had MIBG-positive lesions and tumor-free, cryopreserved hematopoietic stem cells. Activity was administered according to body weight and protocol as part of a phase I and phase II study. The whole-body radiation dose was derived from daily 1-m exposure measurements, the tumor self-absorbed radiation dose (TSARD) was determined from scintillation-camera conjugate views, and the tumor volume was measured using CT or MRI.

RESULTS

Forty-two patients with refractory neuroblastoma (16 with prior hematopoietic stem cell transplant) received a median activity of 555 MBq/kg (15 mCi/kg) (range, 93-770 MBq/kg) and a median total activity of 11,470 MBq (310 mCi) (range, 3,330-30,969 MBq). The median whole-body radiation dose was 228 cGy (range, 57-650 cGy) and the median TSARD was 3,300 cGy (range, 312-30,500 cGy). Responses among evaluable patients included 16 partial response, 3 mixed response, 14 stable disease, and 9 progressive disease. Higher TSARD values predicted better overall disease response (P < 0.01). The median decrease in tumor volume was 19%; 18 tumors decreased, 4 remained stable, and 5 increased in size. Correlation was seen between administered activity per kilogram and whole-body dose as well as hematologic toxicity (assessed by blood platelet and neutrophil count nadir) (P < 0.05). The median whole-body dose was higher in the 11 patients who required hematopoietic stem cell infusion for prolonged neutropenia versus the 31 patients who did not (323 vs. 217 cGy; P = 0.03).

CONCLUSION

Despite inaccuracies inherent in dosimetry methods, (131)I-MIBG activity per kilogram correlated with whole-body radiation dose and hematologic toxicity. The TSARD by conjugate planar imaging predicted tumor volume decrease and also correlated with overall tumor response.

Phase I dose escalation of 131I-metaiodobenzylguanidine with autologous bone marrow support in refractory neuroblastoma

PURPOSE

The analogue 131I-metaiodobenzylguanidine (MIBG), which is specifically targeted to neuroblastoma cells, may provide more effective and less toxic treatment for neuroblastoma than conventional external-beam radiotherapy. We report a dose escalation study of 131I-MIBG to define dose-limiting toxicity without and with autologous bone marrow support.

PATIENTS AND METHODS

Thirty patients with relapsed neuroblastoma were treated in groups of six with escalating doses of 3 to 18 mCi/kg of 131I-MIBG. After rapid escalation in the first three patients treated at 3 to 6 mCi/kg, treatment was escalated in 3-mCi/kg increments from 9 to 18 mCi/kg. Autologous tumor-free bone marrow was cryopreserved in all patients receiving 12 mCi/kg and more. Toxicity and response were assessed.

RESULTS

Eighty percent of patients who received 12 mC/kg or more experienced grade 4 thrombocytopenia and/or neutropenia. Dose-limiting hematologic toxicity was reached at 15 mCi/kg, at which level two of five assessable patients required bone marrow reinfusion for absolute neutrophil count (ANC) of less than 200/microL for more than 2 weeks, and four of nine at the 18-mCi/kg level. Prolonged thrombocytopenia was common, with failure to become platelet-transfusion independent in nine patients. One patient with extensive prior treatment developed secondary leukemia and three became hypothyroid. Responses were seen in 37% of patients, with one complete response (CR), 10 partial response (PR), three mixed response, 10 stable disease, and six progressive disease. The minimum dose of 131I-MIBG for 10 of the 11 responders was 12 mCi/kg.

CONCLUSION

Treatment with 131I-MIBG has mainly hematologic toxicity, which can be abrogated with bone marrow rescue. The high response rate in refractory disease suggests that this agent may be useful in combination with myeloablative chemotherapy and autologous stem-cell rescue to improve outcome in advanced neuroblastoma.

Quantification of tissue plasma volume in the rat by contrast-enhanced magnetic resonance imaging

Magnetic resonance imaging enhanced with a macromolecular contrast medium (MMCM), albumin-Gd-DTPA, was used to estimate the plasma volume in vivo in the myocardium, lung, liver, and skeletal muscle of 10 normal rats. The plasma volumes of the same tissues in a parallel group of six rats were estimated in vitro by a conventional radioisotopic technique (111In-transferrin). Plasma volumes of myocardium, lung, liver, and skeletal muscle estimated by the MR technique (microliter plasma cc-1 of tissue) were 101, 109, 163, and 11.0, respectively, while plasma volumes measured by the 111In-transferrin radioisotope technique (mg plasma g-1 of tissue) were 78.6, 215, 143, and 11.2, respectively. Assuming a ratio of densities of aerated lung to blood of 0.45 and of other tissues to blood of 1.0, correlation between the methods was excellent (R2 = 0.99) indicating that MR imaging enhanced with MMCM permits reliable in vivo estimation of tissue plasma volume in the rat.

Effect of liposome composition and other factors on the targeting of liposomes to experimental tumors: biodistribution and imaging studies

We have examined the distribution of radiolabeled liposomes in tumor-bearing mice after i.v. injection. Two mouse tumors (B16 melanoma, J6456 lymphoma) and a human tumor (LS174T colon carcinoma) inoculated i.m., s.c., or in the hind footpad were used in these studies. When various liposome compositions with a mean vesicle diameter of approximately 100 nm were compared using a radiolabel of gallium-67-deferoxamine, optimal tumor localization was obtained with liposomes containing a phosphatidylcholine of high phase-transition temperature and a small molar fraction of monosialoganglioside or hydrogenated phosphatidylinositol (HPI). At 24 h after injection, average values of tumor uptake higher than 10% of the injected dose per g and liver-to-tumor ratios close to 1 were reproducibly obtained. Increasing the molar fraction of HPI from 9% to 41% of the total phospholipid resulted in enhancement of liver uptake and decrease of tumor uptake. Methodological aspects that influence vesicle size appear to affect significantly liposome localization in the tumor. However, varying the phospholipid dose within a 10-fold range caused only minor changes in the percent of injected dose recovered in the tumor. A high uptake by tumors was also observed using other radiolabels [[3H]inulin and indium-111-labeled bleomycin (111In-Bleo)] in monosialoganglioside- and HPI-containing liposomes. In the case of 111In-Bleo, encapsulation in liposomes resulted in approximately 20- to 40-fold increase in tumor accumulation of the radiolabel at 24 h after injection. The marked localization of liposomes in the mouse footpad inoculated with tumor as opposed to the contralateral mock-injected footpad was also documented by imaging experiments with gallium-67-deferoxamine and 111In-Bleo-labeled liposomes. These results support the contention that some glycolipid-containing liposomes previously shown to have long circulating half-lives accumulate significantly in a variety of tumors and are promising tools for the delivery of anti-tumor agents.

The effects of coronary angioplasty and reperfusion on distribution of myocardial flow

To assess the effects of angioplasty (PTCA) and intracoronary streptokinase (ICSK) on relative myocardial perfusion, we administered 99mTc-macroaggregated albumin (MAA) to the uninvolved coronary artery before successful PTCA in 33 patients and before successful infusion of ICSK in eight patients and of 111In-MAA into the same vessel after the intervention. In 10 patients who underwent PTCA, MAA was injected into the involved, instrumented coronary artery. Computer-processed images were acquired in registry and compared. Similar scintigraphic studies were performed in six control patients and in 11 in whom planned interventions were not performed or were unsuccessful. Distribution of MAA was also compared with angiographic results and with the distribution of 201Tl on images obtained in patients at rest or on redistribution images obtained before and soon after intervention in 22 patients. In control patients and those studied after aborted or unsuccessful intervention, scintigraphic results showed excellent correlation with the angiographic anatomy and were without serial change. When MAA was injected into the uninvolved vessel, the scintigram revealed evidence of collateral perfusion with retraction of the perfusion zone from that of the involved coronary in 19 of 33 patients undergoing PTCA and in three of eight of those receiving ICSK. When MAA was injected into the involved artery, a relative increase in perfusion was seen in eight of 10 patients after PTCA. Although 30 patients demonstrated scintigraphic evidence of collateral vessels, only 10 patients had angiographic evidence of collateral circulation before intervention. The distribution of 201Tl demonstrated little change in its global pattern and regions previously supplied by collaterals were generally well perfused after intervention. Coronary collateral perfusion may be inapparent angiographically and regress rapidly after angioplasty or reperfusion. Native perfusion is generally and quickly restored after successful PTCA or ICSK infusion, which obviates the need for collaterals. After intervention, the distribution of total perfusion may not change, but its regional source may demonstrate beneficial alterations, shifting from collateral to native circulation.

The association of Ga-67 and lactoferrin

Activity was seen in the breasts of a patient with galactorrhea 72 h after intravenous injection of Ga-67 citrate. Differential protein separation of breast secretion, extracted from the breast, revealed that the Ga-67 was contained primarily in the lactoferrin-rich protein fraction. Additional studies on partially purified lactoferrin revealed that lactoferrin binds Ga-67 more avidly than does transferrin. Since lactoferrin is present in high concentration non only in human colostrum and milk, but also in neutrophilic leukocytes, bone marrow, spleen, colon, tears, and in genital, salivary, and nasopharyngeal secretions, binding of Ga-67 to lactoferrin may explain the localization of Ga-67 in certain normal tissues and inflammatory lesions.