Characteristics of Conventional and Microwave Sintered Iron Ore Preform

In this study, compacted hematite (Fe₂O₃) preforms were made and sintered at various temperatures, such as 1250 °C and 1300 °C, using both conventional and microwave sintering methods. The density, porosity, microhardness, cold crushing strength, microphotographs, and X-ray diffraction (XRD) analysis of the sintered preforms were used to evaluate the performance of the two sintering methods. It was found that microwave sintered preforms possessed lesser porosity and higher density than conventionally sintered preforms owing to uniform heating of the powdered ore in microwave sintering method. Furthermore, it was also observed that microwave sintered preforms exhibited relatively higher cold crushing strength and hardness than conventionally sintered preforms. Thus, the overall results revealed that microwave sintering yielded better properties considered in the present study.

Correlating Labeling Chemistry and in-vitro Test Results with the Biological Behavior of Radiolabeled Proteins

A study of the effect of various rediochemical labeling parameters on the in-vivo behavior of proteins, in particular of monoclonal antibodies, was carried out. Both radioiodination, and radiometal labeling (using protein-chelating agent conjugates), of antimelanoma, antiplatelet, and anticolon carcinoma monoclonal antibodies (222.28s, 7E3, and GA-733 respectively), as well as the direct labeling of human serum albumin with 99m Tc, were investigated. Different aspects of the biological behavior are affected in relation to the labeling chemistry involved. These include the immunoreactivity, blood clearance and tissue uptake kinetics, and rates and routes of excretion. Individual radionuclide effects have often to be addressed separately. Some antibodies are more susceptable to alteration from labeling conditions than others. Careful optimization of labeling and purification procedures is thus necessary for particular radionuclide/antibody combinations in order to obtain predictable and reproducible in-vivo results for both immunoscintigraphy and immunotherapy applications.

A Comparison of the Cyclic Anhydride and Mixed Anhydride Methods for 111In-DTPA Chelation to Monoclonal Antibodies

The cyclic anhydride (CA) and the mixed anhydride (MA) of DTPA were synthesized and used to chelate 111In to an antimelanoma monoclonal antibody. The CA and MA methods showed mean labeling efficiencies of 25.7 and 20.5%, respectively (p = NS). The binding efficiency of labeled antibody to human melanoma cells in tissue culture also was similar (x̄ = 52 and 50%, respectively, p = NS), as was tumor uptake in nude mice at 96 hrs post-injection (16%-CA vs 12%-MA). The method required less complicated chemical syntheses, much less preparation time, and the product was stable over a much longer period. The results suggest that the CA method is preferable for bifunctional chelate labeling of monoclonal antibodies with 111In-DTPA.

Production of actinomycin-D by the mutant of a new isolate of Streptomyces sindenensis

An actinomycin-D producing strain was isolated from soil and characterized as Streptomyces sindenensis. The culture was subjected to UV irradiation and a mutant with 400% higher actinomycin-D production was isolated (400 mg/l^-1 as compared to 80 mg/l^-1 produced by the parent). Production medium was optimized and antibiotic yield with the mutant was enhanced to 850 mg/l^-1 which is 963% higher as compared with the parent.

Occurrence and distribution of hexachlorocyclohexane isomers in vegetation samples from a contaminated area

The occurrence and distribution of four major hexachlorocyclohexane (HCH) isomers (alpha-, beta-, gamma- and delta-) were studied in vegetation samples of a highly contaminated area close to a small-scale industrial belt in Lucknow (North India). Eight species of plants were collected at different points of the contaminated area and different parts of the plants were separated in order to study the difference in uptake and accumulation. The samples were extracted by matrix solid-phase dispersion (MSPD) extraction and finally determined by a gas-chromatograph equipped with (63)Ni electron capture detector (ECD). HCH isomers were present in almost all samples and the concentration of total HCH in the plant sample analyzed varied between 13 and 44 mg kg(-1), being the main isomer of beta-HCH (8-22 mg kg(-1)). Lindane (gamma-HCH) was present in all samples (1-9 mg kg(-1)). Solanum torvum Sw., and Erianthus munja shows the highest and lowest capacity for accumulation of HCH, respectively with a significant difference at p<0.01 level. The highest concentration of HCH residue in root samples indicates the most likely mechanism of HCH accumulation in these plants was sorption of soil HCH on roots. Solanum torvum Sw., and Withania somnifera (L.) Dunal could accumulate considerable levels of HCH isomers (44 and 34 mg kg(-1), respectively). The results reflect the importance of plants in monitoring purposes and their potential for phytoremediation of HCH contaminated soils.

Adsorption of Cr(VI) and Se(IV) from their aqueous solutions onto Zr4+-substituted ZnAl/MgAl-layered double hydroxides: effect of Zr4+ substitution in the layer

Hydrotalcite-like compounds (layered double hydroxides, LDHs) containing varying amounts of Al(3+), Zr(4+), and Zn(2+) or Mg(2+) in the metal hydroxide layer have been synthesized and characterized by various physicochemical methods. The adsorption behavior of uncalcined (as-synthesized) and calcined LDHs have been investigated for Cr(2)O(7)(2-) and SeO(3)(2-). The mixed oxides, obtained on calcination at 450 degrees C, exhibit high adsorption capacities for Cr(2)O(7)(2-) (1.6-2.7 meq/g) and SeO(3)(2-) (1.1-1.5 meq/g), where adsorption occurs through rehydration. Substitution of Zr(4+) in the LDHs, for either M(2+) or Al(3+) ions, increases the adsorption capacity up to 20%, thus providing an alternative way to enhance the adsorption capacity of this type of material. The high adsorption capacity of these materials could be successfully used for removal of undesirable anions from water and also for synthesis of intercalated materials with tailored acidobasicity.

Marrow-sparing effects of 117mSn(4+)diethylenetriaminepentaacetic acid for radionuclide therapy of bone cancer

Several bone-seeking radionuclides (32P, 89Sr, 186Re, and 153Sm) have been used to treat bone pain. The limiting factor in this modality is marrow toxicity. Our hypothesis is that marrow toxicity can be reduced while maintaining therapeutic efficacy using radionuclides that emit short-range beta particles or conversion electrons (CEs). A recent study on 47 patients using the short-range CE emitter 117mSn(4+)diethylenetriaminepentaacetic acid (117mSn(4+)DTPA) supports this hypothesis. The hypothesis is now tested using 117mSn(4+)DTPA in a mouse femur model.

METHODS

The survival of granulocyte-macrophage colony-forming cells (GM-CFCs) in femoral marrow is used as a biologic dosimeter for bone marrow. The dosimeter is calibrated by irradiating mice with exponentially decreasing dose rates of 137Cs gamma-rays with a dose-rate decrease half-time, Td, equal to the effective clearance half-time of 117mSn(4+)DTPA from the femur (222 h). When Td = 222 h, the mean absorbed dose required to achieve a survival fraction of 37% is 151 cGy. After calibration, 117mSn(4+)DTPA is administered and GM-CFC survival is determined as a function of injected activity. These data are used to experimentally determine the mean absorbed dose to the femoral marrow per unit injected activity. The kinetics of radioactivity in the marrow, muscle, and femoral bone are also determined. Finally, a theoretic dosimetry model of the mouse femur is used, and the absorbed doses to the femoral marrow and bone are calculated.

RESULTS

The experimental mean absorbed dose to the femoral marrow per unit injected activity of 117mSn(4+)DTPA is 0.043 cGy/kBq. The theoretic mean absorbed dose to the femoral bone per unit injected activity is 1.07 cGy/kBq. If these data are compared with those obtained previously for 32P-orthophosphate, the radiochemical 117mSn(4+)DTPA yields up to an 8-fold therapeutic advantage over the energetic beta emitter 32P.

CONCLUSION

The CE emitter 117mSn offers a large dosimetric advantage over energetic beta-particle emitters for alleviating bone pain, and possibly for other therapeutic applications, while minimizing marrow toxicity.

67Cu-2IT-BAT-Lym-1 pharmacokinetics, radiation dosimetry, toxicity and tumor regression in patients with lymphoma

Lym-1, a monoclonal antibody that preferentially targets malignant lymphocytes, has induced therapeutic responses and prolonged survival in patients with non-Hodgkin's lymphoma when labeled with 1311. Radiometal-labeled antibodies provide higher tumor radiation doses than corresponding 1311 antibodies. 67Cu has an exceptional combination of properties desirable for radioimmunotherapy, including gamma and beta emissions for imaging and therapy, respectively, a biocompatible half-time and absence of pathways contributing to myelotoxicity. The radioimmunoconjugate, 67Cu-21T-BAT-Lym-1, has been shown to be efficacious in nude mice bearing human Burkitt's lymphoma (Raji) xenografts. Based on these results, a clinical study of the pharmacokinetics and dosimetry of 67Cu-21T-BAT-Lym-1 in patients with lymphoma was initiated.

METHODS

Eleven patients with advanced stage 3 or 4 lymphoma were given a preload dose of unmodified Lym-1, then an imaging dose of 126-533 MBq (3.4-14.4 mCi) 67Cu-21T-BAT-Lym-1. Total Lym-1 ranged from 25 to 70 mg dependent on the specific activity of the radioimmunoconjugate and was infused at a rate of 0.5-1 mg/min. Imaging, physical examination, including caliper measurement of superficial tumors, and analysis of blood, urine and fecal samples were performed for a period of 6-13 d after infusion to assess pharmacokinetics, radiation dosimetry, toxicity and tumor regression.

RESULTS

In 7 patients, in whom superficial tumors had been accurately measured, tumors regressed from 18% to 75% (mean 48%) within several days of 67Cu-21T-BAT-Lym-1 infusion. The uptake and biological half-time of 67Cu-21T-BAT-Lym-1 in tumors were greater than those of normal tissues, except the mean liver half-time exceeded the mean tumor half-time. The mean tumor-to-marrow radiation ratio was 32:1, tumor-to-total body was 24:1 and tumor-to-liver was 1.5:1. Images were of very good quality; tumors and normal organs were readily identified. Mild and transient Lym-1 toxicity occurred in 6 patients; 1 patient developed a human antimouse antibody. There were no significant changes in blood counts or serum chemistries indicative of radiation toxicity.

CONCLUSION

Because of the long residence time of 67Cu-21T-BAT-Lym-1 in tumors, high therapeutic ratios were achieved and, remarkably, numerous tumor regressions were observed after imaging doses. The results indicate considerable therapeutic potential for 67Cu-21T-BAT-Lym-1.

Radiochemical purification of no-carrier-added scandium-47 for radioimmunotherapy

A procedure, adaptable to large-scale remote operation, was developed to purify no-carrier-added (NCA) 47Sc from irradiated Ti targets. Methods based on extraction chromatography and cation-exchange chromatography were compared. Results of this comparison led to the development of an optimized procedure based on cation-exchange with Dowex AG 50W-X4 and 47Sc elution with HCl/HF. This method gave 90-97% overall 47Sc recovery, with a Ti separation factor greater than 2.4 x 10(-5), and specific activities > or = 0.9 GBq microgram-1. Use of the 47Sc product, for labeling monoclonal antibodies, resulted in consistent labeling yields of > or = 90%.

Maximum tolerated dose of 67Cu-2IT-BAT-LYM-1 for fractionated radioimmunotherapy of non-Hodgkin's lymphoma: a pilot study

PURPOSE

Lym-1, a monoclonal antibody (MoAb) that preferentially targets malignant lymphocytes, has induced therapeutic responses in patients with non-Hodgkin's lymphoma (NHL) when labeled with iodine-131 (131I). Radiometal labeled antibodies provide a higher tumor radiation dose than the corresponding 131I labeled antibodies. Based on the strategy of fractionating the total radiation dose, this study was designed to define the maximum tolerated dose (MTD) of the first 2, of a maximum of 4, doses of 67Cu-2IT-BAT-Lym-1 given 4 weeks apart. Additionally, toxicity, radiation dosimetry and efficacy were assessed.

MATERIALS AND METHODS

Patients had Ann Arbor stage IVB NHL, resistant to standard therapy, including multiple chemotherapy regimens. Each dose of 67Cu-2IT-BAT-Lym-1 was given after a preload of unmodified Lym-1. A 10 mCi imaging dose of 67Cu-2IT-BAT-Lym-1 was given in order to assess pharmacokinetics and radiation dosimetry prior to therapy. Based on the MTD for 131I-Lym-1 and comparative dosimetry for 131I-Lym-1 and 67Cu-2IT-BAT-Lym-1, the trial was initiated at 60 millicuries per square meter of body surface area (mCi/m2) in cohorts of 3 patients.

RESULTS

A single cohort of patients proved sufficient to define the MTD as 60 mCi/m2 for each of the first 2 doses of 67Cu-2IT-BAT-Lym-1. The dose-limiting toxicities were grade 3-4 thrombocytopenia and neutropenia. Neutropenic sepsis and bleeding did not occur. Mean radiation dose contributed to the bone marrow by 67Cu in the body and blood was 0.2 (range, 0.2 to 0.3) rads/mCi. Copper-67 incorporated into ceruloplasmin contributed 25% of the dose to marrow from blood. Non-hematologic toxicities did not exceed grade 2. The three patients had substantial tumor regression even after imaging doses of 67Cu-2IT-BAT-Lym-1. After therapy, one response was complete with a duration of 12 months. Radiation doses to tumors in this patient varied from 7.0-21.9 rads/mCi or 5420-7000 total rads from the course of therapy.

CONCLUSION

67Cu-2IT-BAT-Lym-1 provided good imaging, favorable radiation dosimetry and a remarkably high therapeutic index (ratio of tumor to marrow radiation doses). The non-myeloablative MTD for each of 2 doses was 60 mCi/m2.

Radiopharmaceuticals for bone malignancy therapy

OBJECTIVE

This continuing education article reviews radionuclide bone therapy agents that are available commercially and introduces agents that are being evaluated for future use. Currently these agents are used to provide pain palliation from metastases to bone. Future applications may include adjuvant therapy to surgery or external beam treatment. After reading this paper, the reader should be able to: (a) describe the desirable characteristics of radionuclide bone therapy agents; (b) compare and contrast radiopharmaceuticals available for bone therapy; and (c) state the clinical applications of radionuclide bone therapy agents.

In-vivo tissue uptake and retention of Sn-117m(4+)DTPA in a human subject with metastatic bone pain and in normal mice

Organ and tissue uptake and retention of Sn-117m(4+)DTPA were studied in a human subject treated for metastatic bone pain, and the results were compared with the biodistribution studies in five normal mice. The explanted organs from a patient who received a therapy dose of 18.6 mCi (688.2 MBq) Sn-117m(4+)DTPA and who died 47 days later were imaged with a gamma-camera, and tissue samples were counted and also autoradiographed. Bone, muscle, liver, fat, lungs, kidneys, spleen, heart and pancreas tissue samples were assayed in a well counter for radioactivity. Regions of interest were drawn over bone and major organs to calculate and quantify clearance times using three in vivo Sn-117m(4+)DTPA whole-body scintigrams acquired at 1, 24 and 168 h after injection. Five normal mice injected with the same batch of Sn-117m(4+)DTPA as used for the human subject were sacrificed at 24 h, and tissue samples were collected and assayed for radioactivity for comparison with the human data. For the human subject, whole-body retention at 47 days postinjection was 81% of the injected dose, and the rest (19%) was excreted in urine. Of the whole-body retained activity at 47 days, 82.4% was in bone, 7.8% in the muscle and 1.5% in the liver, and the rest was distributed among other tissues. Gamma-ray scintigrams and electron autoradiographs of coronal slices of the thoracolumbar vertebral body showed heterogeneous metastatic involvement with normal bone between metastatic lesions. There was nonuniform distribution of radioactivity even within a single vertebral body, indicating normal bone between metastatic lesions. Lesion-to-nonlesion ratios ranged from 3 to 5. However, the osteoid-to-marrow cavity deposition ratio, from the microautoradiographs, was 11:1. The peak uptake in the human bone was seen at 137 h with no biological clearance. Soft tissues showed peak uptake at 1 h and exhibited three compartmental clearance components. Whole-body retention in normal mice was 38.7% of the injected dose at 24 h and the rest was excreted. At 24 h postinjection, bone in mice showed 84.2% of the whole-body retention, muscle 1.7% and liver 1.4%, and the rest was distributed in other soft tissues. Percent distribution of the retained dose among bone, muscle, liver and other soft tissues is very similar between mice and a human subject. To calculate precise radiation absorbed doses from bone pain palliation radionuclides, it is necessary to take into account soft-tissue uptake and retention that may not be readily evident from routine external gamma-scintigraphy.

Radionuclide development at BNL for nuclear medicine therapy

Radionuclides with medium energy beta emission and a several day half-life have often been viewed as attractive candidates for radioimmunotherapy. Among the most promising in this category are 47Sc, 67Cu, 153Sm, 188Re, and 199Au. The production of 67Cu, 153Sm, 199Au at BNL is summarized and the development of the latest candidate for this application, 47Sc, is described in detail. We also summarize the development of another important therapeutic radionuclide, 117mSn for bone pain palliation.

Treatment of metastatic bone pain with tin-117m Stannic diethylenetriaminepentaacetic acid: a phase I/II clinical study

The physical characteristics of Sn-117m combined with the biodistribution of the compound tin-117m (Stannic, 4+) diethylenetriaminepentaacetic acid (Sn-117m DTPA) suggest that it should be an excellent agent for the palliation of pain from bony metastases. Prior work has established the dosimetry and the safety for the material in human beings. The presence of low-energy conversion electrons should result in the relative sparing of the bone marrow while delivering a high radiation dose to sites of bony metastatic disease. Forty-seven patients with painful bone metastases from various malignancies were treated with Sn-117m DTPA. The patients were assigned to five different dose levels ranging from 2.64 to 10.58 MBq (71-286 microCi) per kg of body weight. Follow-up included review of pain diaries, performance scores, analgesic requirements, blood chemistries, and hematological assessment. Three patients received a second treatment. There was an overall response rate for relief of pain of 75% (range, 60-83%) in the 40 treatments that could be evaluated. No correlation was apparent in this limited series between response rate and the five dose levels used. The relief was complete in 12 patients (30%). The time to onset of pain relief was 19 +/- 15 days with doses < or = 5.29 MBq/kg and 5 +/- 3 days with doses > or = 6.61 MBq/kg. Myelotoxicity was minimal, with only one patient having a marginal grade 3 WBC toxicity. On the basis of our data, Sn-117m DTPA should be an effective and safe radiopharmaceutical for palliation of painful bony metastases. A large-scale trial is warranted to evaluate it in comparison to other similar agents.

Enhancement of 67Cu-2IT-BAT-LYM-1 therapy in mice with human Burkitt's lymphoma (Raji) using interleukin-2

BACKGROUND

Lymphomas have been shown to be responsive to 131I immunoconjugates in studies conducted in mice and patients. We have observed that copper 67 (67Cu)-labeled Lym-1 remains in lymphomatous tissue longer than 131I-Lym-1 and, consequently, results in higher absorbed radiation doses to tumors. In addition, recombinant interleukin-2 (rIL-2) has been reported to increase tumor uptake of radiolabeled antibody. Therefore, we examined the efficacy of 67Cu-labeled Lym-1 and the ability of rIL-2 to enhance this efficacy in athymic mice implanted with Raji xenografts.

METHODS

6[p-(bromoacetamido) benzyl]-1,4,8,11-tetraazacyclotetradecane-N,N', N'',N'''-tetraacetic acid (BAT) was conjugated to Lym-1 via 2-iminothiolane (2IT) to prepare 2IT-BAT-Lym-1, which was labeled with 67Cu. Mice with Raji xenografts were treated with 335-500 microCi (12.4-18.0 MBq) of 67Cu-2IT-BAT-Lym-1 with or without 48,000-144,000 IU of rIL-2 once or were treated b.i.d. for 5 days beginning simultaneously with 67Cu-2IT-BAT-Lym-1. Mouse weight, blood counts, and mortality were monitored to assess toxicity, and tumor size was measured to assess efficacy. In addition, groups of mice were sacrificed to assess the biodistribution of 67Cu-2IT-BAT-Lym-1 with and without rIL-2.

RESULTS

In mice treated with 335 microCi of 67Cu-2IT-BAT-Lym-1 alone, 28% of tumors were cured. When 48,000 IU of rIL-2 were added, 50% were cured. The overall response-rate was 50% for both regimens. In mice treated with 400 microCi of 67Cu-2IT-BAT-Lym-1 alone, 42% responded, all of which were cured. When 48,000 IU of rIL-2 were added, 77% of tumors responded, and 38% were cured. Larger or multiple doses of rIL-2 did not result in additional therapeutic enhancement. The tumor uptake and radiation dose after 67Cu-2IT-BAT-Lym-1 were about two times greater when a single dose of rIL-2 was added: This may be the basis for enhanced therapeutic efficacy. Mortality was not altered for 335 microCi or 400 microCi doses of 67Cu-2IT-BAT-Lym-1 by rIL-2 nor were other toxicity parameters. Mortality was increased at 500 microCi by the addition of rIL-2.

CONCLUSIONS

67Cu-2IT-BAT-Lym-1 provided a therapeutic and frequently curative dose of radiation to tumored mice at tolerated doses. The therapeutic effectiveness of 67Cu-2IT-BAT-Lym-1 may have been enhanced by rIL-2.

Tin-117m(4+)DTPA: pharmacokinetics and imaging characteristics in patients with metastatic bone pain

Biokinetics and imaging characteristics of 117mSn(4+)DTPA have been studied in patients with metastatic bone pain.

METHODS

Seventeen patients with bone pain due to metastasis were given three dose levels: 180 microCi/kg (6.66 MBq/kg), 229 microCi/kg (8.47 MBq/kg) and 285 microCi/kg (10.55 MBq/kg) body weight. Periodic blood and daily urine samples were collected for 14 days to measure percent injected activity retained in blood and that excreted in urine. Simultaneous anterior and posterior view whole-body images were obtained under identical scan settings at 1, 3.5 and 24 hr and on Days 3 and 7 and between 4-6 and 8-10 wk postinjection. The total body retention was calculated using the geometric mean counts.

RESULTS

After intravenous injection, the total body clearance of 117mSn(4+)DTPA shows two components: a soft-tissue component and a bone component. The soft-tissue component accounts for 22.4% of the dose and consists of four subcomponents with an average biologic clearance half-time of 1.45 days (range 0.1-3.2 days). The bone component accounting for the remaining 77.6% of the dose shows no biologic clearance. A mean 22.4% of the dose is excreted in urine in 14 days; 11.4% within 24 hr. The uptake pattern appears similar to that of 99mTc-MDP. Peak uptake is observed in normal bone by 24 hr and metastatic lesions by 3-7 days. Pain palliation was observed with all three doses levels.

CONCLUSION

Among the four potential bone pain palliation radionuclides, 117mSn(4+)DTPA demonstrates the highest bone uptake and retention. Some biokinetic and radionuclidic features of 117mSn(4+)DTPA are similar to other agents, but many features are different and unique and may make it an ideal bone pain palliation agent. Double-blind comparative studies are needed to determine its exact role in bone pain palliation.

Efficacy and toxicity of 67Cu-2IT-BAT-Lym-1 radioimmunoconjugate in mice implanted with human Burkitt's lymphoma (Raji)

Radioimmunotherapy has shown promising results for treatment of radiosensitive malignancies such as lymphoma. Positive responses have been reported in patients with non-Hodgkin's lymphoma treated with 131I-radiolabeled Lym-1, a mouse anti-lymphoma monoclonal antibody. In this study, the efficacy of 67Cu-radiolabeled Lym-1 was examined. Nude mice bearing human Burkitt's lymphoma (Raji) tumors (20-524 mm3) were treated with 12.4, 14.8, 18.5, and 23.3 MBq of 67Cu-2IT-BAT-Lym-1. Tumor size was measured to assess efficacy, and mouse weight, blood counts, and mortality were monitored to assess toxicity. In mice treated with 12.4, 14.8, and 18.5 MBq of 67Cu-2IT-BAT-Lym-1, 50% (9 of 18), 42% (5 of 12), and 50% (3 of 6) of tumors achieved remission or cure; 33% of tumors were cured overall; and significant regrowth delay was observed. The 23.3 MBq dose group did not yield meaningful efficacy data because of high mortality. In control groups receiving 14.8 and 18.5 MBq of the isotype-matched nonspecific monoclonal antibody radioimmunoconjugate, 67Cu-2IT-BAT-L6, 0% (0 of 15) and 17% (2 of 12) of tumors achieved a response; hence, targeted delivery of radiation was the dominant antitumor mechanism of 67Cu-2IT-BAT-Lym-1. LD50/30 for mice treated with 67Cu-2IT-BAT-Lym-1 and -L6 were 21.6 and 20.6 MBq, respectively. In conclusion, 67Cu-2IT-BAT-Lym-1 provided a therapeutic and frequently curative dose of radiation to tumored mice with modest toxicity.

Radiolabeled bone-seeking radiopharmaceuticals

Bone seeking radiopharmaceuticals consist of diagnostic (primarily single photon emitters) and therapeutic agents. The therapeutic radiopharmaceuticals are utilized on the basis of their particulate emissions (primarily beta-) and thus are treated differently than the single photon bone imaging agents. Lately, the therapeutic bone seekers have attained increasing importance due to their potential role in alleviating pain from osseous metastases in cancer patients. However, there seems to be a paucity of published data on the pharmacokinetics of most of these agents. This paper will briefly review and summarize the presently available pharmacokinetic information on the various therapeutic bone seeking radiopharmaceuticals. Bone imaging agents based on single photon emitters will not be covered since they have been extensively discussed in the published literature.

Pre-clinical and clinical studies of two new bifunctional chelating agents for immunoscintigraphy with 111In-anti-CEA monoclonal antibody

Anti-CEA F(ab')2 monoclonal antibody fragments [F6 MAb F(ab')2] were conjugated to two bifunctional semi-rigid chelating agents derived from trans-1,2-diaminocyclohexane tetraacetic acid (CDTA), the monolithium salt of N-[methyl(2-isothiocyanatoethyl)carbamide] trans-1,2-diaminocyclohexane-N,N',N'-triacetic acid (SCN), and 4 isothiocyanato-trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (4-ICE) and labelled with 111In to obtain IIIIn-labelled-F6 MAb F(ab')2 conjugates (111In-F6-SCN and 111In-F6-4-ICE respectively). Biodistribution in mice and clinical studies were undertaken to assess the potential of these two ligands in the detection of colorectal adenocarcinoma recurrences and metastases in humans. Toxicity studies were carried out on guinea pigs and Swiss mice injected with a dose proportionally 100 times greater than that used in human studies. Clinical studies were performed in patients with clinically and/or biologically suspected adenocarcinoma recurrences. No immunoconjugate-induced toxicity was found. The biodistribution studies in mice gave better visualization of tumour sites with 111In-F6-SCN and 111In-F6-4-ICE than with 111In-F6-DTPA. Ten patients were included in the clinical protocol. 111In-F6-SCN and 111In-F6-4-ICE effectively visualized adenocarcinoma recurrences. However, in this small series, 111In-F6-4-ICE performed somewhat better than 111In-F6-SCN. The present study has demonstrated the potential of new bifunctional semi-rigid chelating agents coupled to antibody and labelled with 111In to localize recurrences (especially in liver) in humans using a one-step targeting method.

Is there life after technetium: what is the potential for developing new broad-based radionuclides?

The use of radionuclides for medical and for a multitude of other basic research applications has continued to grow at a very rapid pace. Procedures, based on their use as radiotracers for nuclear medicine imaging and for radiotherapy of cancer and other pathology, have become firmly established as important clinical modalities. It is estimated that on an annual basis in the United States alone, radionuclides are used medically in over 13 million imaging procedures, in over 100 million laboratory tests, and in an ever increasing number (> 100,000) for therapeutic administrations. One out of every four hospital patients undergoes a procedure that involves the use of radionuclides. Diagnostic imaging methods using planar/single-photon emission computed tomography and positron-emission tomography (PET) imaging, as well as the measurement of in vivo organ function, physiology, or biochemistry, have become indispensable tools in patient workup and management. More than 80% of all imaging studies (mostly anatomic) currently use technetium-99m (99mTc), because it has turned out to be the ideal isotope from various considerations. However, over the past few years, nuclear medicine has experienced a slow but steady evolution towards functional studies, quantitative PET imaging, and novel therapeutic approaches. New radionuclides are required for these applications, and their development has attracted considerable interest. This article reviews the current status and future prospects for the development of many new potential isotopes. Practical issues, such as the feasibility of large-scale production and wide-spread availability in a continuous reliable fashion, are addressed. To date, the data are not sufficient to answer the question as to whether any of these radionuclides (or their applications, for that matter) will eventually assume as broad-based a role as that of 99mTc. Nonetheless, there are a number of promising radionuclides that could assume an important place in the future practice of nuclear medicine.

Criteria for the selection of radionuclides for targeting nuclear antigens for cancer radioimmunotherapy

The potential of utilizing immunoconjugates to selectively deliver radionuclides for the destruction of tumors has stimulated much research activity. From dosimetric and other considerations, the choice of radiolabel is an important factor that needs to be optimized for maximum effectiveness of radioimmunotherapy (RIT). This paper reviews and assesses a number of present and future radionuclides that are particularly suitable for RIT based on the various physical, chemical, and biological considerations. Although intermediate to high-energy beta emitters (with and without gamma photons in their emission) possess a number of advantages for most RIT, the use of alpha, Auger, and short range conversion electron emitters could be attractive for targeting nuclear antigens when the radioimmunoconjugate is internalized into tumor cells. Factors relating to the production and availability of candidate radionuclides as well as their stable chemical attachment to monoclonal antibodies are discussed.

Effect of oral administration of carbofuran on male reproductive system of rat

1. Carbofuran was administered orally to adult male rats at dose levels of 0.1, 0.2, 0.4 or 0.8 mg kg-1 body weight, 5 d wk-1 for 60 days. A dose dependent decrease was observed in body weight of rats treated with 0.2-0.8 mg carbofuran kg-1 body weight. 2. A significant decrease in the weight of epididymides, seminal vesicles, ventral prostate and coagulating glands was observed at various test doses of carbofuran except at the lowest dose. 3. Decreased sperm motility, reduced epididymal sperm count along with increased morphological abnormalities in head, neck and tail regions of spermatozoa were observed in rats exposed to 0.2, 0.4, or 0.8 mg carbofuran kg-1 body weight. 4. In addition, significant alterations were observed in the activities of marker testicular enzymes viz. sorbitol dehydrogenase (SDH), glucose-6-P-dehydrogenase (G6PDH) (decreased), lactate dehydrogenase (LDH) and gamma-glutamyl transpeptidase (gamma-GT) (increased) depending on dose. 5. Histologically, the results indicated the toxicity of carbofuran on testes depending on dose. The changes predominantly consisted of moderate oedema, congestion, damage to Sertoli cells and germ cells, along with the accumulation of cellular debris and presence of giant cells in the lumen of a few seminiferous tubules which showed disturbed spermatogenesis with the higher doses of carbofuran. 6. These observations determined a no effect level dose of 0.1 mg kg-1 body weight of carbofuran on the biochemical and morphological indices studied for male reproductive toxicity assessment in the rat model. The results of the present study provide first hand information on the reproductive toxicity of carbofuran in male rats.

Factors regulating methyl mercury uptake in a cyanobacterium

The simultaneous addition of dithiothreitol (DTT), mercaptoethanol, and glutathione (30 microM each) and CH3Hg+ to Nostoc calcicola cells reduced CH3Hg+ uptake in the order GSH > DTT > mercaptoethanol. However, the preexposure of cyanobacterial cells to similar thiols resulted in different pattern of CH3Hg+ uptake in the sequence: GSH > mercaptoethanol > DTT. Light-grown cyanobacterial cells demonstrated a faster initial uptake of CH3Hg+ (rate 0.619 mumol CH3Hg+ mg-1 protein min-1, 10 min) with a biphasic pattern saturating at 30 min (bioconcentration factor = 2.7 x 10(3)). 3-(3,4-Dichlorophenyl)-1,1'-dimethyl urea (30 microM) reduced the uptake rate by 5% with a corresponding 33% reduction in CH3Hg+ accumulation. Dark exposure (24 hr) of cells reduced the CH3Hg+ uptake rate (22.3%) accompanied by a considerable decline in the bioconcentration factor (1.4 x 10(3)). Of the four permeabilizers used, p-chloromercuribenzoate (1 microM) proved most effective in altering the CH3Hg+ uptake kinetics while dimethyl sulfoxide (5%) and cetyl trimethylammonium bromide (1%) lowered the bioconcentration factor to 2.2 x 10(3) and 1.2 x 10(3), respectively. After toluene exposure, however, the cells revealed no sign of CH3Hg+ uptake. The data have been discussed in light of the role(s) of thiols, photoautotrophy, and membrane integrity in regulating the cellular influx of CH3Hg+.

Effects of carbaryl on the rat's male reproductive system

Carbaryl was orally administered to male albino rats at 50 mg or 100 mg carbaryl/kg body weight 5 d/w for 90 d. A significant decrease in weight gain was observed at the high dosage after 60 d. Although no significant changes in the weight of testes, epididymides and accessory sex organs occurred, moderate to marked histopathological changes in the testes were seen at both dosage levels. Testicular enzymes associated with post-meiotic spermatogenic cells (sorbitol dehydrogenase) decreased, while lactate dehydrogenase increased concomitant with the observed degeneration of spermatogenic cells. Enzymes associated with pre-meiotic spermatogenic cells or Sertoli cells (gamma-glutamyl transpeptidase) increased, while glucose-6-phosphate dehydrogenase decreased. These effects were dose related and associated with declines in epididymal sperm count and percent sperm motility and increased abnormal sperm morphology.

Effect of dermal application of hexachlorocyclohexane (HCH) on male reproductive system of rat

1. The toxic manifestations of dermally applied hexachlorocyclohexane (50 mg or 100 mg kg-1 body weight day-1, 5 days in a week for 120 days) on testes and sperm of rat have been investigated. 2. The results indicate that exposure of HCH through the dermal route could lead to an alteration in the activities of marker testicular enzymes viz. sorbitol dehydrogenase (SDH), glucose-6-P-dehydrogenase (G6PDH), gamma-glutamyl transpeptidase (gamma-GT) and beta-glucuronidase (beta Gluc.) associated with specific cell types. 3. Significant quantities of HCH and its isomers accumulated in testes as well as sperm of treated rats. 4. HCH exposure also led to a decrease in serum testosterone levels, epididymal sperm count, sperm motility and an increase in the percentage of abnormal sperm. 5. These observations indicate the possibility of adverse effects of HCH on the male reproductive functions of men exposed dermally to this pesticide in industry or during spraying in the field.

Tin-117m(4+)-DTPA for palliation of pain from osseous metastases: a pilot study

The physical and biological attributes of 117mSn(4+)-DTPA indicate that it should be an effective agent for palliative therapy of painful bony metastatic disease. The aim of this study was to evaluate whether or not this agent could effectively reduce pain while sparing the hemopoietic marrow from adverse effects.

METHODS

Fifteen patients (10 males and 5 females) with painful bony metastases from various primary cancers were included in the study. Seven patients received 1.22 to 3.11 MBq/kg of 117mSn intravenously (Group 1) and eight patients received 4.85 to 5.77 MBq/kg (Group 2). All but one were treated as outpatients and followed for a minimum of 2 mo.

RESULTS

In the first group, pain relief was non-assessable in four patients because of death or additional treatment of soft-tissue disease by another modality. One patient had no relief of pain, one had complete relief of pain and one had transient relief of pain. No myelotoxicity was observed. For Group 2, three patients achieved complete relief of pain, two good relief, two partial relief and one began to experience pain relief when he suffered a pathological fracture 2 mo post-treatment. None of these patients had myelotoxicity.

CONCLUSION

Tin-117m(4+)-DTPA can reduce pain from metastatic disease to bone without inducing adverse reactions related to bone marrow. Further studies are needed to assess tolerance levels for the bone marrow and to evaluate response rates and duration of effect.

Effect of hexachlorocyclohexane (HCH) on testicular plasma membrane of rat

The study deals with the analysis of residue of hexachlorocyclohexane (HCH) and its possible damaging potential on testicular plasma membrane of rats. In vitro studies were conducted by exposing plasma membrane of testis with 1.46 x 10(-5) M, 2.92 x 10(-5) M, 4.38 x 10(-5) M, 7.30 x 10(-5) M, 1.46 x 10(-4) M and 2.92 x 10(-4) M HCH at 37 degrees C for 15 min. The results indicate inhibition in the activity of the Ca(2+)-ATPase, Na(+)+K(+)+Mg(2+)-ATPase and 5'Nucleotidase. In vivo studies were carried out following repeated dermal exposure to HCH at a dose level of 50 or 100 mg/kg/day for 60 days to male rats. The results show significant decrease in the activities of 5'-Nucleotidase, Ca(2+)-ATPase, Na(+) + K(+)-ATPase and Mg(2+)-ATPase in the plasma membrane of testis following exposure to HCH. The analysis of the residues of HCH reveals the presence of significant quantities of its different isomers viz., alpha, beta, gamma and delta in the testicular plasma membrane of rats given in vivo dermal exposure of this pesticide. These results suggest that the presence of HCH residue may be a factor in inhibiting the marker enzymes of the plasma membrane of testis.

1,N6-etheno deoxy and ribo adenosine and 3,N4-etheno deoxy and ribo cytidine phosphoramidites. Strongly fluorescent structures for selective introduction in defined sequence DNA and RNA molecules

Synthesis of 1,N6-etheno-2'-deoxyadenosine, 3,N4-etheno-2'-deoxycytidine, and further chemistry on both deoxy and ribo series etheno nucleosides produces the corresponding phosphoramidites. These novel phosphoramidites are introduced selectively, quantitatively, and at specific positions at single or multiple sites into DNA or RNA sequences. The purification and chemistry involved in the synthesis of these products has been optimized to achieve the purity in excess of 99%. The resulting phosphoramidites were tested for their ability to couple and produce poly deoxy and ribonucleotides by solid phase chemistry. The coupling efficiency achieved was greater than 99% per step. Due to the instability of these etheno compounds in acidic and basic medium, various criteria to obtain pure oligomers have been established. The selective introduction of these fluorescent nucleosides into defined sequence DNA and RNA molecule will greatly facilitate the structure-function studies of various RNAs, protein-RNA structures, and DNA-RNA based diagnostics applications. The characteristic and high fluorescent intensity (detection below 1 x 10(-9) M for adenosine sites and below 1 x 10(-7) M for cytidine sites) is particularly suited for the biochemical and biological research and product development applications. The usefulness of these etheno containing modified sequences as sequencing and amplification primers is demonstrated by their full participation in polymerase chain reaction experiments.

Liver plasma membrane-bound enzymes and lipids in golden hamsters infected with Ancylostoma ceylanicum

Infection of golden hamsters with Ancylostoma ceylanicum caused significant decrease in body weight, liver weight and the protein content of liver plasma membrane. Significant inhibition of liver plasma membrane enzymes activities-5'Nucleotidase, gamma-glutamyl transpeptidase, NADHK3Fe (CN)6 reductase, Na+/K(+)-ATPase, CA(2+)-ATPase and Mg(2+)-ATPase was observed in infected animals compared to corresponding controls. Sialic acid content and phospholipid/cholesterol ratio in liver plasma membrane of the infected group were significantly reduced. The study suggests that changes in both the structural and functional organization of membrane may be a biochemical basis of the hepatotoxic effects.

Introduction of five potentially metabolizable linking groups between 111In-cyclohexyl EDTA derivatives and F(ab')2 fragments of anti-carcinoembryonic antigen antibody--II. Comparative pharmacokinetics and biodistribution in human colorectal carcinoma-bearing nude mice

The five linker-containing immunoconjugates described in the preceding paper were labeled with 111In and tested for their biodistribution, pharmacokinetics and immunoscintigraphic imaging properties in tumor-xenografted nude mice. The results were compared with DTPADA and CDTAMA for reference. Results showed that, for immunoscintigraphy, the derivatives in decreasing order of effectiveness were: aliphatic (tumor/liver > 4.5 and tumor/kidney > 6.5 at 96 h), thioether (tumor/liver > 3 and tumor/kidney > 1.2 at 24 h), ethylene glycol succinate (tumor/liver > 1.7 and tumor/kidney > 0.5 at 24 h) and disulfide (tumor/liver > 0.5 and tumor/kidney > 0.6 at 96 h). Pharmacokinetic results were complementary with those of the biodistribution studies and provide a basis for the study of in vivo metabolic mechanisms of linker-immunoconjugates. Indium-111-labeled linker-immunoconjugates appear promising for tumor imaging with better contrast than what is obtained with the use of the conventional 111In-DTPA dianhydride chelate.

Introduction of five potentially metabolizable linking groups between 111In-cyclohexyl EDTA derivatives and F(ab')2 fragments of anti-carcinoembryonic antigen antibody--I. A new reproducible synthetic method

The purpose of this study was to synthesize new bifunctional linker-chelating agents for the modification of the in vivo distribution of 111In-labeled antibodies. A general simple synthetic method of preparing cyclohexyl EDTA (CDTA) derivatives containing a linker/spacer group is described. Linkers prepared included a diester, a six carbon aliphatic chain, two thioethers and a disulfide group. The CDTA-linker compounds were coupled to F(Ab')2 fragments of anti-carcinoembryonic antigen monoclonal antibody and labeled with 111In with good retention of immunoreactivity.

Biodistribution of Sn-117m(4+)DTPA for palliative therapy of painful osseous metastases

Tin-117 has certain physical characteristics (half-life of 13.6 days, low-energy-conversion electrons, gamma photon of 158.6 keV) that suggest that it may be a favorable agent for radionuclide therapy. It has been shown in animal models that Sn-117m in the chemical form Sn(4+)diethylenetriaminepentaacetic acid localizes selectively in bone. The authors therefore studied its whole-body distribution in 10 patients to obtain absorbed dose estimates for therapy. The results showed that more than 50% of the administered activity was absorbed in the bones of patients with metastatic carcinoma. Retention was determined primarily by radioactive decay. For adult men, the radiation absorbed dose estimate averaged 54.8 mGy/MBq (203 rad/mCi) to bone surfaces and 6.1 mGy/MBq (22.6 rad/mCi) to the red marrow. All other tissues received less than 1/10 of the dose received by red marrow. These results suggest that a clinical therapeutic trial should be attempted.

The use of a new radiopharmaceutical, 97Ru-DISIDA, and of 99Tcm-sulphur colloid for the simultaneous evaluation of duodenogastric reflux and gastric emptying

There is no consensus or a uniform technique for measuring gastric emptying and numerous modalities have been reported. We report here the results obtained using a modification of the published techniques for the simultaneous measurement of duodenogastric reflux and gastric emptying utilizing simultaneously the recently developed radiopharmaceutical 97Ru-DISIDA, intravenously, and the oral administration of 99Tcm-sulphur colloid incorporated in a 'solid' test meal.

Interpretation of treadmill stress test in patients with coronary artery disease receiving beta blocker therapy

Graded maximal treadmill exercise responses were studied before and after beta blockade (atenolol 100 mg once daily for 2 weeks) in 20 male patients with chronic stable angina. Beta-blocking effect consisted of significant reduction of resting heart rate (HR) by 21%, systolic blood pressure (SBP) by 12% and rate pressure product (RPP) by 30%. While the maximum exercise capacity was marginally increased by mean 1.7 min +/- 1.6 SD (P less than 0.001) under the influence of therapy, peak HR, SBP and maximum RPP were significantly lower (P less than 0.001) than in preatenolol exercise tests. Similarly, while the configuration and magnitude of ST segment depression did not differ materially between the pre and post atenolol tests, onset time of ST change was delayed and offset time shortened significantly. These parameters cannot be relied upon to assess the extent and severity of coronary artery disease (CAD) if stress test is carried out while the patient is on a beta-blocking drug. The overall sensitivity of the stress test to detect coronary disease is, however, not likely to be compromised because of negligible influence of beta-blockers upon ST segment depression provided maximally tolerated (not submaximal) exercise is performed. ST/HR slope, an exercise test variable known to correlate well with the extent of CAD, was shown to be uninfluenced by beta-blockade. Its measurement is therefore recommended in interpreting stress tests performed in patients receiving beta-blocker therapy. This, however, requires a meticulously prepared protocol of recording computer averaged QRST complexes and multilead ECG tracings at very frequent intervals throughout the exercise.(ABSTRACT TRUNCATED AT 250 WORDS)