Clinical Implementation of Weak Magnetic Field Generator in Radiation Therapy

PURPOSE/OBJECTIVE(S)

The application of weak magnetic fields may improve radiation therapy efficacy by manipulating the free radical activity induced by radiation to optimize tumor death. Once the device is commercially available, we will conduct clinical trials to determine the clinical impact of the weak magnetic field. However, the magnetic field generator (MFG) restricts Linac gantry rotation to approximately 180° and this limitation may limit treatment plan quality. This work is a continuation of an ongoing study to determine if the gantry angle restrictions can be compensated for during treatment planning.

MATERIALS/METHODS

Previous work has demonstrated the feasibility for GBM cases. For this work, 10 prostate cancer treatment plans were retrospectively replanned using only coplanar arcs that spanned from 90° to 270° (half-arcs). The prescriptions were 60 Gy for 6 patients, 55.8 Gy for 2 patients, 54 Gy for 1 patient, and 40.05 Gy for 1 patient. The prescription doses were delivered to 95% of the planning target volume (PTV = GTV + 2 cm). The critical structure doses were compared to determine if clinically equivalent plans could be delivered using half-arcs.

RESULTS

The dose criteria that were met by the clinical plans were also met by the half-arc plans except for the cases shown in Table 1. Table 1: Doses that did not meet criteria CONCLUSION: The half-arc plans were able to deliver clinically equivalent dose distributions as the clinical treatment plans. This provides continuing evidence that clinical trials will be able to be developed to evaluate the use of weak magnetic fields for radiation therapy.

Phase I trial of IL-2 plasmid DNA with electroporation in metastatic melanoma

8578

Background: Significant toxicity limits the systemic delivery of high-dose recombinant Interleukin-2 (IL-2). An alternative method for extended dosing of IL-2 that may reduce toxicity is by intratumoral injection of IL-2 plasmid DNA (pDNA) with electroporation (EP). Methods: A phase I dose-escalation trial is ongoing in subjects with metastatic melanoma to evaluate the safety of intratumoral delivery of IL-2 pDNA (VCL-IM01, Vical Inc., San Diego, CA) followed by EP (MedPulser DNA EPT System, Inovio, San Diego, CA). Eligible subjects have recurrent metastatic melanoma; an injectable lesion = 1 cm2 and < 25 cm2; ECOG 0 or 1; LDH = 1.5 × ULN, and no brain or liver metastases. In the dose-escalation stage of the trial, 3 subjects in each dose cohort received up to 2 cycles of treatment, each consisting of 4 weekly injections followed by a 4-week observation period. Dose levels included 0.5, 1.5, 5.0 mg/tumor, and 15.0 mg (5 mg in each of 3 tumors). A safety assessment was conducted for each cohort prior to enrollment of the next cohort. In the 2nd trial stage, 17 subjects are to be enrolled at the maximum tolerated dose (MTD). The observation period is shortened to 2 weeks between cycles. For all subjects, safety is assessed at every visit. Results: 12 subjects (7 male, 5 female) were enrolled in the dose escalation stage, 3 subjects at each dose. Ages range from 38 to 86 years. No Grade 3 or 4 adverse events (AEs) were reported related to study drug or procedures. All related AEs (12 reported) were Grade 1: 5 related to study drug, 4 to the EP procedure, and 3 to both. Injection site pain was the most common AE. No dose-limiting toxicities occurred; thus the MTD was defined as the 15 mg dose (5 mg/tumor in 3 tumors). To date, 6/17 subjects in Stage 2 of the trial (5 mg/tumor, up to 3 tumors injected) have been enrolled with no Grade 3 or 4 AEs related to study drug or injection/EP procedures. Physicians have observed responses in treated and untreated lesions. Overall response data will be presented. Conclusions: Intratumoral administration of IL-2 pDNA with EP appears safe and well tolerated in 18 patients with metastatic melanoma when given up to a 15 mg dose (5 mg/tumor). Preliminary indications of decreased tumor size suggest local and systemic activity of IL-2 pDNA with EP.

No significant financial relationships to disclose.

The psychological and physical health of hospice caregivers

This study explores the psychological distress of caring for a dying family member and examines the differences in depression, anxiety, health, social and occupational functioning, and social support among hospice caregivers and community controls. It compares psychological functioning of spousal and adult child hospice caregivers. Caregivers of terminally ill hospice patients were assessed prior to death as a part of a longitudinal bereavement study. Caregivers reported experiencing higher levels of depression, anxiety, anger, and health problems than controls. Hospice caregiving was associated with deterioration in physical health and in social and occupational functioning. The comparisons between adult children and spouse caregivers revealed that levels of psychological and physical morbidity were very similar for the two generations of caregivers. An awareness of distress symptoms among hospice caregivers could lead to timely proactive clinical intervention that may prevent bereavement complications.

The family experience of cancer pain management in children

This study describes the family perspective of cancer pain management in pediatric patients. Family caregiver knowledge and attitudes regarding pain, caregiver burden associated with pain, and caregiver moods were identified. This study was conducted in a children's hospital (n = 31) and a community hospice (n = 8) with family caregivers of pediatric cancer patients as the participants. Pain intensity was rated by children and family caregivers using pain assessment scales applicable to children with cancer. Differences in pain ratings were reported. The Family Pain Questionnaire was used to identify parents' knowledge and attitudes about pain and its management. Areas for family teaching were identified with the questionnaire. Understanding the pain experience from the perspective of family caregivers and their role in pain management can assist healthcare providers in relieving pain in children with cancer.

Spinal bone loss in postmenopausal women supplemented with calcium and trace minerals

The effects of calcium supplementation (as calcium citrate malate, 1000 mg elemental Ca/d) with and without the addition of zinc (15.0 mg/d), manganese (5.0 mg/d) and copper (2.5 mg/d) on spinal bone loss (L2-L4 vertebrae) was evaluated in healthy older postmenopausal women (n = 59, mean age 66 y) in a 2-y, double-blind, placebo-controlled trial. Changes (mean +/- SEM) in bone density were -3.53 +/- 1.24% (placebo), -1.89 +/- 1.40% (trace minerals only), -1.25 +/- 1.46% (calcium only) and 1.48 +/- 1.40% (calcium plus trace minerals). Bone loss relative to base-line value was significant (P = 0.0061) in the placebo group but not in the groups receiving trace minerals alone, calcium alone, or calcium plus trace minerals. The only significant group difference occurred between the placebo group and the group receiving calcium plus trace minerals (P = 0.0099). These data suggest that bone loss in calcium-supplemented, older postmenopausal women can be further arrested by concomitant increases in trace mineral intake.

Spinal bone density and calcium intake in healthy postmenopausal women

Dietary calcium intake and bone mineral density (BMD) of the lumbar spine (L2-L4) were determined in 131 healthy free-living postmenopausal women (aged 64.7 +/- 7.6 y, means +/- SD). The calcium consumption for the total population was 606 +/- 302 mg/d. Subjects consuming less than the population mean of dietary calcium had significantly lower BMDs than did subjects with intakes above the mean (P less than 0.009); these two groups did not differ in basic demographic characteristics. Additional analyses using a stepwise univariate regression model demonstrated that BMD was significantly associated with body weight (P less than 0.001) and dietary calcium intake (P less than 0.02). These data support the hypothesis that dietary calcium intake is a determinant of skeletal health in postmenopausal women.

Long-term estrogen replacement therapy in postmenopausal women sustains vertebral bone mineral density

The cross-sectional relationship between long-term estrogen use and vertebral (L2-4) bone mineral density (BMD) was determined in 65 postmenopausal white women between 55 and 75 years who were at least 10 years from their menopause. Long-term estrogen users began therapy within 5 years of menopause and continued for a duration of at least 10 years. The mean duration of use was 19.8 years. Controls used estrogen for less than 1 year. There was a significant difference (p less than 0.02) in mean spinal BMD between estrogen users (1.219 g/cm2) and controls (1.092 g/cm2). There was no significant difference in age, height, weight, or dietary calcium (Ca) intake between the two groups. The statistical difference in BMD was retained when (1) 23 estrogen users were paired with age-matched controls, (2) only women with a natural menopause or history of bilateral oophorectomy were included, and (3) only women with a natural menopause were compared. A spinal BMD below the estimated fracture threshold of 0.965 g/cm2 was found in 11 of 40 controls and only 2 of 25 estrogen users. Comparison of estrogen users with a natural menopause to those with bilateral oophorectomy revealed no significant difference in BMD. These data confirm the salutary effect of long-term estrogen use in the maintenance of vertebral bone mass in postmenopausal women.

A comparison of quantitative dual-energy radiographic absorptiometry and dual photon absorptiometry of the lumbar spine in postmenopausal women

Noninvasive bone densitometry is an important aspect in the detection and management of osteoporosis and other forms of metabolic disease of calcified tissue. A system using quantitative dual-energy digital projection radiography (QDR) of the lumbar spine was systematically tested against dual-photon absorptiometry (DPA) of the lumbar spine in 131 women over 55 years of age and free from major risk factors for osteoporosis. All subjects were scanned by both QDR and DPA under the same conditions. Measurements for a given subject were made within 15 minutes of each other. Bone mineral densities (BMD) were determined for four individual levels in the lumbar spine (L1-L4). Regression equations for BMD vs. age, height, and weight were calculated. The results of this investigation indicate that DPA- and QDR-derived BMD values are comparable. BMD values derived by QDR were consistently lower than those obtained by DPA (DPA = 1.115 QDR + 0.137, r = 0.942). The L2 lumbar region was the most strongly correlated determination.

Serum zinc is unaffected by effective captopril treatment of hypertension

Captopril, a sulfhydryl compound that lowers blood pressure by inhibiting the zinc metalloenzyme, angiotensin converting enzyme, may occasionally result in ageusia, a symptom also associated with zinc deficiency. We therefore studied serum zinc and copper concentrations in a group of 14 essential hypertensive subjects before treatment and after 5-6 months of antihypertensive oral monotherapy with either captopril (50 mg, twice daily; n = 7) or other drugs (propranolol or alphamethyldopa; n = 7). Serum zinc and copper were unaltered by either regimen. Thus, zinc depletion is an unlikely consequence of long-term exposure to captopril, at least in the dosages commonly used for treatment of hypertension.

The effect of deficiencies of manganese and copper on osteoinduction and on resorption of bone particles in rats

Subcutaneous implantation of devitalized demineralized bone powers (DBP) and mineral-containing bone particles (BP) into rats raised on either a control (C), low manganese and low copper (L), or manganese-deplete (D) diet, allowed the separate evaluation of bone formation and of bone resorption, respectively. DBP failed to induce chondrogenesis or osteogenesis in D rats. Cartilage formation was delayed in the L rats compared to C rats. There was significantly less resorption of BP by L and D rats than C rats. These results show multiple cellular effects of long-term manganese (Mn) and copper (Cu) deficiencies on bone metabolism including decreased osteogenesis and a decrease in osteoclast activity.

The oral assimilation of radiomanganese by the mouse

The metabolism of orally administered radiomanganese was studied in mice. Assimilation of absorbed manganese (Mn) was determined using whole body counting techniques. When(54)MnCl2 was administered, 2.7% of the dose was retained after 10 d compared with 1.2% from the(54)Mn-nitrilotriacetate (NTA) complex. However, this difference was accounted for by the rapid and persistent adsorption of the Mn onto the teeth of the lower jaw when fed as the ionic salt at pH 2.0 compared with the NTA-chelate fed at pH 9.0. Once corrected for the amount adsorbed onto the teeth, the biodistribution and relative specific activity of the assimilated radiomanganese into a variety of tissues were similar for both forms of the metal.

Transitory hematologic effects of moderate exercise are not influenced by iron supplementation

A young women's exercise/fitness class tested the idea that administration of supplemental iron would prevent "sports anemia" that may develop during exercise and training and improve iron status of exercising females of menstrual age. Fifteen women (aged 18-37) were selected for each of three treatment groups: (1) no supplemental iron; (2) 9 mg X d-1 of Fe; and (3) 18 mg X d-1 of Fe (1 US Recommended Daily Allowance). Women exercised at approximately 85% of maximal heartrate for progressively increasing lengths of time in a jogging program and worked up to 45 min of exercise 4 d X week-1 for 8 weeks. Hematologic analysis was performed in weeks 1, 5, and 8. A significant decline in hemoglobin (Hb) concentration and hematocrit (Hct) was observed at week 5 when all data were examined without regard for iron intake; these red cell indices returned to pre-exercise levels by week 8. Reduction of mean cell hemoglobin concentration (MCHC) indicated that the midpoint decline was not caused by simple hemodilution during exercise. Serum ferritin (SF) concentration changed in parallel with Hb and Hct. Although the midpoint decline in SF was not statistically significant, it ruled out the possibility that turnover of red cell iron was directed to storage. Lowered MCHC and SF suggested lower availability of iron during the synthesis of a new generation of red cells. Few iron treatment effects of magnitude were observed. Iron did not prevent the midpoint decline in Hb concentration. Iron intake did not affect SF, serum iron, transferrin saturation, or final Hb, and Hct.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitochondrial NADH dehydrogenase in iron-deficient and iron-repleted rat muscle: an EPR and work performance study

Iron may affect both respiratory O2 transport and mitochondrial electron transport in the performance of muscle work. This study was designed to elucidate the molecular defect of iron-deficient work performance by identifying heretofore unmeasurable mitochondrial enzymes that are diminished by iron deficiency and may be restored by iron repletion. Female rats were made iron-deficient by dietary control and were repleted by oral iron. Iron deficiency reduced physical work capacity (treadmill running time), haemoglobin (Hb), and mitochondrial iron-sulphur (Fe-S) centres in heart and skeletal muscles; mitochondrial number was unaffected. Oral iron supplementation restored work capacity and Hb within 4 d to normal or near-normal levels, but in general Fe-S centres of mitochondria due to NADH dehydrogenase remained at iron-deficient levels. Subnormal concentrations of mitochondrial iron-dependent NADH dehydrogenase in muscle are not by themselves rate-limiting in work performance.