Quantification of in vivo site-specific Asp isomerization and Asn deamidation of mAbs in animal serum using IP-LC-MS.

BACKGROUND: Isomerization of aspartic acid and deamidation of asparagine are two common amino acid modifications that are of particular concern if located within the complementarity-determining region of therapeutic antibodies. Questions arise as to the extent of modification occurring in circulation due to potential exposure of the therapeutic antibody to different pH regimes. RESULTS: To enable evaluation of site-specific isomerization and deamidation of human mAbs in vivo, immunoprecipitation (IP) has been combined with LC-MS providing selective enrichment, separation and detection of naive and modified forms of tryptic peptides comprising complementarity-determining region sequences. CONCLUSION: IP-LC-MS can be applied to simultaneously quantify in vivo drug concentrations and measure the extent of isomerization or deamidation in PK studies conducted during the drug discovery stage.

Effects of co-culture of cumulus oocyte complexes with denuded oocytes during in vitro maturation on the developmental competence of cloned bovine embryos.

This study evaluated the effects of co-culture of immature cumulus oocyte complexes (COCs) with denuded immature oocytes (DO) during in vitro maturation on the developmental competence and quality of cloned bovine embryos. We demonstrated that developmental competence, judged by the blastocyst formation rate, was significantly higher in the co-cultured somatic cell nuclear transfer (SCNT+DO, 37.1 ± 1.1%) group than that in the non-co-cultured somatic cell nuclear transfer (SCNT-DO, 25.1 ± 0.9%) group and was very similar to that in the control IVF (IVF, 38.8 ± 2.8%) group. Moreover, the total cell number per blastocyst in the SCNT+DO group (101.7 ± 6.2) was higher than that in the SCNT-DO group (81.7 ± 4.3), while still less than that in the IVF group (133.3 ± 6.0). Furthermore, our data showed that mRNA levels of the methylation-related genes DNMT1 and DNMT3a in the SCNT+DO group were similar to that in the IVF group, while they were significantly higher in the SCNT-DO group. Similarly, while the mRNA levels of the deacetylation-related genes HDAC2 and HDAC3 were significantly higher in the SCNT-DO group, they were comparable between the IVF and SCNT+DO groups. However, the mRNA levels of HDAC1 and DNMT3B were significantly higher in the SCNT+DO group than in the other groups. In conclusion, the present study demonstrated that co-culture of COCs with DO improves the in vitro developmental competence and quality of cloned embryos, as evidenced by increased total cell number.

9-cis Retinoic acid inhibits cumulus cell apoptosis during the maturation of bovine cumulus-oocyte-complexes.

Cumulus cell (CC) apoptosis is inversely correlated with embryonic development in vitro. Therefore, inhibition of CC apoptosis is important for proper embryonic development and quality. Retinoic acids (all-transRA and 9-cisRA) are natural components of retinoids, and 9-cisRA is the physiologically active metabolite of retinoic acid in vitro. During in vitro maturation, 9-cisRA enhances oocyte competence through multiple mechanisms affecting the oocyte and preimplantation embryo; however, the effect of 9-cisRA on CC apoptosis has yet to be elucidated. The aim of the present study was to evaluate the effect of 9-cisRA on CC apoptosis and to identify the molecular mechanism underlying that effect. Bovine slaughterhouse cumulus-oocyte complexes (COC) were matured in vitro in the absence or presence of 5 nM 9-cisRA. Cumulus cells were collected from immature and matured COC for the detection of apoptosis and gene expression analysis. Results showed that 9-cisRA reduced the number of apoptotic CC by about 2.7 fold (P < 0.023), compared with control. However, apoptosis is rare in CC of immature COC (0.01% ± 0.001). Transcripts involved in the caspase cascade were down-regulated upon exposure to 9-cisRA, including tumor necrosis factor alpha (TNF-α, 11.1 fold, P < 0.001), tumor necrosis factor alpha receptor 1 (TNFR1, 2.3 fold, P < 0.01), caspase 9 (CASP9, 2.0 fold, P < 0.031), caspase 8 (CASP8, 2.2 fold, P < 0.012), and caspase 3 (CASP3, 2.1 fold, P < 0.006), while antiapoptotic B-cell lymphoma 2 (BCL2) transcript was increased (3.1 fold, P < 0.004), compared with control. In addition, 9-cisRA inhibited mitogen activated protein kinase mRNA expression in CC, including extracellular signal-regulated kinase 1/2 (ERK1, 2.7 fold, P < 0.02; ERK2, 2.7 fold, P < 0.03), and c-Jun N-terminal kinase (JNK, 1.6 fold, P < 0.044), as well as the activator protein-1 (AP1) family members c-jun (1.6 fold, P < 0.041) and c-fos (2.0 fold, P < 0.06). The transcript abundances of TNF-α, TNFR1, CASP9, CASP8, CASP3, ERK1, ERK1, JNK, and BCL2 were increased, while c-fos and c-jun mRNA expression was decreased in the matured CC. On the basis of the data, we suggest that 9-cisRA inhibits CC apoptosis during in vitro maturation of bovine COC.

Coculturing denuded oocytes during the in vitro maturation of bovine cumulus oocyte complexes exerts a synergistic effect on embryo development.

The present study examined the effect of coculturing cumulus oocyte complexes (COCs) and denuded oocytes (DOs) during in vitro maturation (IVM) on nuclear and cytoplasmic maturation, zona pellucida (ZP) hardening, the pattern of fertilization and glutathione peroxidase 1 (GPX1) gene expression in the oocyte. Furthermore, the rate of embryonic development and the quality of blastocysts were examined for both COCs and DOs. Three IVM conditions were studied: 1) the coculture of 12 COCs and 60 DOs, 2) COC control with 12 COCs, and 3) DO control with 60 DOs. The IVM was performed in a 120-µl droplet of TCM199-based IVM medium. Following IVM, in vitro fertilization (IVF) and in vitro culture (IVC) were conducted separately for the COCs and DOs (DO coculture) from the IVM coculture group. Coculturing COCs and DOs increased the percentage of oocytes reaching the blastocyst stage and the total number of cells per blastocyst in both the COC coculture (44.4 ± 8.6 vs 26.7 ± 9.7%, P < 0.01, and 137.9 ± 24.9 vs 121.7 ± 21.1, P < 0.05) and the DO coculture (20.5 ± 5.0 vs 11.1 ± 2.5%, P < 0.01, and 121.9 ± 27.5 vs 112.3 ± 33.2, P < 0.05) compared to their respective control groups. The synergistic effects of coculturing were detected as increased nuclear and cytoplasmic maturation, the prevention of ZP hardening, increased monospermic fertilization and increased expression of GPX1 in the oocytes in response to endogenous oocyte-secreted factors. In conclusion, coculturing COCs and DOs may be an effective culture system for both intact COCs and immature DOs.

9-cis retinoic acid improves developmental competence and embryo quality during in vitro maturation of bovine oocytes through the inhibition of oocyte tumor necrosis factor-α gene expression.

Retinoic acid (RA; all-trans RA and 9-cis RA) enhances embryo developmental competence and quality through multiple mechanisms affecting the oocyte and preimplantation embryo. Folliculogenesis and oocyte maturation are influenced by tumor necrosis factor-α (TNF-α) via inhibition of aromatase activity and estradiol secretion in granulosa cells. Retinoic acid inhibits TNF-α production in various cell lines. The aim of the present study was to determine whether oocyte TNF-α concentrations regulate developmental competence and embryo quality and if the beneficial effects of 9-cis RA are mediated through attenuation of oocyte TNF-α production. Bovine cumulus oocyte complexes collected from abattoir ovaries were matured in maturation medium in the absence (control) or presence of 5 nM 9-cis RA (RA), 100 ng/mL of recombinant bovine TNF-α (TNF), or 5 nM 9-cis RA + 100 ng/mL of recombinant bovine TNF-α (RA+TNF). Oocytes were subsequently collected for gene expression analysis or subjected to in vitro fertilization and culture. Apoptosis and gene expression were analyzed in d-8 blastocysts. Results indicated that 9-cis RA downregulated (P < 0.01) both basal and TNF-α-induced TNF-α mRNA in oocytes (1.0-fold in control, 0.4-fold in RA, 2.1-fold in TNF, and 0.7-fold in RA+TNF). The 9-cis RA increased (P < 0.001) blastocyst development rates (37.1 ± 6.9 vs. 23.6 ± 8.0%) and total cell number (138.4 ± 19.2 vs. 120.2 ± 24.5) and reduced (P < 0.001) the percentage of apoptotic cells (3.3 ± 2.0 vs. 5.6 ± 2.3%) compared with controls. Expression of caspase 3 (0.4- vs. 1.0-fold) and TNF-α (0.4- vs. 1.0-fold) mRNA was downregulated (P < 0.05) in RA-treated blastocysts compared with controls. Moreover, 9-cis RA rescued (P < 0.001) development rates (24.5 ± 11.1 vs. 15.6 ± 9.0%), increased total cell number (124.6 ± 36.5 vs. 106.9 ± 31.1), and reduced apoptosis (5.8 ± 2.0 vs. 8.1 ± 3.1%) in blastocysts exposed to TNF-α (TNF group). Caspase 3 (0.8-fold in RA+TNF vs. 2.2-fold in TNF) and TNF-α (0.3-fold in RA+TNF vs. 2.8-fold in TNF) mRNA expression was attenuated (P < 0.05) in TNF-α-treated blastocysts. In conclusion, the present study suggests that 9-cis RA exerts its beneficial roles on oocyte developmental competence and embryo quality by attenuating oocyte TNF-α mRNA expression.

Effect of equine chorionic gonadotropin on the efficiency of superovulation induction for in vivo and in vitro embryo production in the cat.

The effects of various dosages of equine chorionic gonadotropin (eCG) on superovulation induction for in vivo and in vitro embryo production were examined in stray cats (Felis catus). Cats (n=286) were allocated into five treatment groups with 0, 50, 100, 200, or 400 IU eCG, followed by 100 IU human chorionic gonadotropin (hCG). In vivo- and in vitro-produced blastocysts were obtained by artificial insemination (AI) and in vitro fertilization (IVF), somatic cell nucleus transfer (SCNT), or parthenogenetic activation (PA). The percentage of cats that developed mature follicles, the percentage of cats with collected embryos, and the mean number of in vivo blastocysts per cat were higher in the 200 IU treatment group (43.9%, 31.8%, and 1.53, respectively) compared with those of the other groups (P<0.05). The percentage of follicular developed cats, the percentage of cumulus-expanded oocytes, and the mean number of collected cumulus-oocyte complexes per cat in the 200 IU (56.7%, 67.8%, and 26.2, respectively) and 400 IU (53.3%, 64.2%, and 26.7, respectively) groups were higher than those in the other groups (P<0.05). Furthermore, the percentage of in vitro-produced blastocyst per cleaved embryos and the average cell number of the blastocysts from IVF (52.7% and 125.8, respectively) was higher than those of the blastocysts from PA (30.1% and 85.2) and higher than those of the blastocysts from SCNT (15.3% and 37.5; P<0.05). In conclusion, the current study demonstrated that in vivo and in vitro embryo production were affected by the dosage of eCG; the best results were obtained with 200 IU.

Effect of cytoplasmic lipid content on in vitro developmental efficiency of bovine IVP embryos.

The objective was to evaluate the effect of cytoplasmic lipid content on the embryonic developmental efficiency of bovine in vitro embryo production (IVP) embryos. Ovaries from Korean native cows (Bos taurus coreanae) were collected from a local abattoir, and cumulus-oocyte complexes (COCs) were recovered from follicles 2 to 8mm in diameter. The oocytes were divided into three groups, dependent on their cytoplasm color: pale color (PC), brown color (BC), and dark color (DC). The COCs were fertilized using frozen-thawed semen from a single Hanwoo bull. Based on measurement of the cytoplasmic color intensity of oocytes after 22h of in vitro maturation (IVM), the DC group had lower (P<0.05) color intensity than that in the BC and PC groups (56.3+/-2.7, 93.3+/-5.1, and 123.9+/-12.0, respectively). Based on MitoTracker Green FM staining, the number of mitochondria in the DC (170.1+/-31.2) group was significantly higher than that in the BC (137.5+/-30.8) and PC (105.5+/-25.3) groups. The cleavage rate in the DC (81.5%) group was also higher than that in the PC (50.4%) group (P<0.05), as was the development rate to blastocyst stage (18.9% vs. 9.8%). Finally, cell numbers of blastocysts in the DC (150.8+/-28.0) group were higher (P<0.05) than that in the BC (107.6+/-17.8) and PC (80.5+/-12.3) groups. In conclusion, cytoplasm color was a useful selection parameter for abattoir-derived oocytes destined for IVP.

Hermeneutic notions augment cultural safety education.

Nurses are beginning to demand educational approaches that confront racism, rather than teach cultural diversity. One example of the latter approach is the introduction of kawa whakaruruhau, or cultural safety, in nursing and midwifery education in New Zealand. In the nursing and midwifery context of kawa whakaruruhau, nurses and midwives recognize, respect, and nurture the unique cultural identity of New Zealand's indigenous people, the tangata whenua, and safely meets their needs, expectations, and rights. In this article, I integrate literature pertaining to the implementation of cultural safety with the findings of a hermeneutic project that described the experience of nursing people from cultures other than one's own, and argue that the Gadamerian notions of "horizon," "prejudice," and "play" can be used to facilitate understanding of the tensions and contradictions inherent in cross-cultural practice. In addition, I recommend strategies that enable students to explore the prejudices, paradoxes, and possibilities experienced personally and professionally. As Gadamer noted, the art is in seeing what is questionable. There is also art in knowing how to question in a manner that makes new understanding possible.

Ifosfamide/carboplatin/etoposide (ICE) as front-line, topotecan/cyclophosphamide as second-line and oral temozolomide as third-line treatment for advanced neuroblastoma over one year of age.

Children affected by advanced neuroblastoma have a discouraging prognosis, but intensive induction chemotherapy may increase the complete response rate. The combination of ifosfamide, carboplatin and etoposide (ICE) was used for the first time as front-line regimen in patients with stage 4 neuroblastoma over the age of 1 y. Similarly, second-line treatment for children with relapsed neuroblastoma, particularly after high-dose chemotherapy, has been unsatisfactory. The combination of topotecan and cyclophosphamide was studied in resistant or relapsed solid tumors. Furthermore, there is a need for effective palliative treatment in patients failing therapy. Temozolomide, a new dacarbazine analog with optimal oral bioavailability, is being used in an ongoing phase II study as an alternative to oral etoposide. Seventeen patients with stage 4 neuroblastoma have entered the ICE study; 15/16 (94%) major responses after induction were observed and 6/16 (37%) evaluable patients are disease free after a median of 51 mo. Twenty-one patients with relapsed/refractory disease (of whom 13 neuroblastomas) entered the topotecan/cyclophosphamide study: 7/21 (33%) patients responded. Forty-one patients entered the temozolomide study (of whom 16 had neuroblastomas): stable disease and symptom relief were obtained in 15/30 (50%) evaluable patients. Intensive induction with ICE resulted in a faster response with high response rate; a larger study with longer follow-up is needed to confirm a survival advantage. Second-line treatment was effective in obtaining remissions, some of them long lasting. Third-line treatment did not elicit measurable responses in neuroblastoma, but achieved prolonged freedom from disease progression and excellent palliation in several patients.

Shortened time to recovery from chemotherapy induced neutropenia in pediatric patients with high dose combined cytokines.

Granulocyte colony stimulating factor (G-CSF) and granulocyte macrophage colony stimulating factor (GM-CSF) are cytokines which have been extensively administered as monotherapy to patients with a variety of hematopoietic disorders at dosages of 5 mcg/kg/day. Because their spectrum of activity is both singular and simultaneously overlapping, we postulated that combined therapy would be more advantageous than monotherapy. Since 1992 we have carried out a study of G-CSF and GM-CSF as monotherapy or in combination in pediatric patients with solid tumors following chemotherapy induced nadirs of 0-800 WBC/mm3. When combined, the cytokines were given twice per day at 2.5 or 5.0 mcg/kg. For the monotherapy groups, either cytokine at 5 mcg/kg or 10 mcg/kg was given once daily. The mean time to recovery from neutropenia nadir ranged from 6.6-8.2 days in patients receiving a total of 10 mcg/kg/day compared to 10.4-10.6 days in patients treated with 5 mcg/kg/day. Side effects were ephemeral eosinophilia. The dosage of 10 mcg/kg/day appears to be a better dosage for pediatric patients with a slight advantage in the combined twice a day schedule (6.6 days).

The response of parotid hemangiomas to the use of systemic interferon alfa-2a or corticosteroids.

OBJECTIVE: To evaluate medical treatment for hemangiomas involving the parotid area with or without other areas of involvement. DESIGN: Retrospective analysis of pediatric patients treated medically for proliferative hemangiomas of the parotid region with or without hemangiomas in other regions. Indications for treatment included respiratory symptoms relating to hemangiomas of the upper airway, difficulty feeding, rapid rate of growth of the hemangioma, and deformity or obstruction of the ear canal. SETTING: New York University Multidisciplinary Vascular Anomaly Conference, New York, NY, and the Pediatric Oncology Department of Ospedale Pediatrico Bambino Gesu, Rome, Italy. PATIENTS: Thirteen patients with proliferative hemangiomas in the parotid area were treated medically to inhibit growth and enhance involution of the hemangioma. INTERVENTION: Six patients were treated with corticosteroids alone (2-4 mg/kg daily). Two patients were treated with corticosteroids (2-4 mg/kg daily) followed by interferon alfa-2a (3 million U/m2 daily) because of a failure to respond to corticosteroid therapy. One patient was treated with interferon alfa-2a alone (3 million U/m2 daily). Four patients were initially treated with interferon alfa-2a, then treated with corticosteroids. One of these patients required intralesional corticosteroid therapy for a massively enlarged lip and is therefore included in this group. The other patient was given oral corticosteroids for unknown reasons at another institution. In the remaining 2 patients, there was no response to the use of interferon alfa-2a. MAIN OUTCOME MEASURES: The size, bulk, and symptoms relating to the hemangiomas of the patients were assessed. RESULTS: None of the patients had a significant improvement of the lesions of the parotid hemangiomas. In contrast, for those patients with clinical symptoms due to hemangiomas elsewhere or with cutaneous involvement typical of hemangiomas, the symptoms improved with either of the above therapies, and the cutaneous areas demonstrated signs of involution. CONCLUSIONS: The results in the 13 patients in this article demonstrate that hemangiomas in certain anatomic sites, such as the parotid area, may be more resistant to therapy with corticosteroids or interferon alfa-2a. Differences in drug metabolism, caliber of blood vessels, and/or blood flow in the parotid gland may account for this observation.

Spindle cell (Kaposiform) hemangioendothelioma with Kasabach-Merritt syndrome in an infant: successful treatment with alpha-2A interferon.

A two-month-old infant developed a vascular tumor of the right flank which upon biopsy proved to be a spindle cell hemangioendothelioma. The increased capillary bed characterizing the neoplasm caused a severe thrombocytopenia together with a consumption coagulopathy (Kasabach-Merritt syndrome). The patient, who was dependent on platelet transfusions, improved quickly after interferon alpha-2a was given at the dosage of 3,000,000 U/m2, with resolution of the Kasabach-Merritt syndrome after three weeks and a 75% decrease of the tumor volume within three months of treatment.

Sporadic acute lymphocytic leukemia arising in a patient with neurofibromatosis and xanthogranulomatosis.

We present a case report of a child who developed acute lymphoblastic leukemia, neurofibromatosis, optic glioma, and xanthogranulomatosis. This complex is unusual, not previously described, and appears to be a coincidence of different diseases. The importance of this case is that it may offer a clue to the genetic base of neurofibrosis syndromes including leukemic associations.

Role of deferoxamine in tumor therapy.

Several studies are consistent with the hypothesis that available iron may have some role in promoting tumor cell growth with different biological mechanisms. For this reason, several studies have been carried out to demonstrate the antitumor activity of deferoxamine (DFO), an iron chelator with a high affinity for ferritin-bound iron. In particular, the effects of DFO have been studied in patients with neuroblastoma, where ferritin is in part tumor derived and high concentrations correlate with poor outcome. To date, in vitro and in vivo studies demonstrating the antitumor effects of DFO are very promising, but further investigations are required to establish an exact role for DFO in the treatment of cancer.

[123I]MIBG scintigraphy in neuroblastoma: a comparison between planar and SPECT imaging.

The aim of the present study was to assess the utility of SPECT imaging with [123I]MIBG in patients with neuroblastoma (NB). Twenty-two children were studied (11 males and 11 females: age range: newborn to 11 years). A total of 39 studies were performed in different clinical phases. Both planar (at 24 and occasionally 48 hours) and SPECT (at 24 hours) imaging were performed in all cases. Planar studies gave a sensitivity of 87.5% (evidence of the disease in 21 of 24 studies performed in children with known NB lesions) and a specificity of 93.3% (true negative results in 14 of 15 studies performed in disease-free patients). In the same patients SPECT gave a sensitivity of 95.8% (23 of 24 positive studies and a specificity equal to that of planar scanning. In 5 of 21 studies positive at planar scanning SPECT showed 9 additional lesions. In conclusion, [123I]MIBG SPECT imaging compared to planar scanning can demonstrate a greater number of lesions. Its use seems to be indicated mainly in cases in which diagnostic assessment is difficult, such as small residual tumors or in the follow up of children no longer in therapy, in whom it can lead to an early diagnosis of relapse.

D-CECaT as preoperative chemotherapy for unresectable neuroblastoma in children over one year of age.

The role of intensive pre- and postoperative chemotherapy in unresectable nonmetastatic neuroblastoma is still controversial. A preoperative regimen that included deferoxamine, cyclophosphamide, etoposide, carboplatin and thiotepa (D-CECaT) was evaluated in 10 children over one year of age at diagnosis, and this was followed by surgery and postoperative chemotherapy. After four courses of D-CECaT, the response rate was 9/10 with 3 complete responses, 6 partial responses and 1 minor response. Severe but transitory myelosuppression was the major toxic effect. Complete remission by combined D-CECaT chemotherapy and surgery was obtained in 9/10 patients, while 1 case achieved complete remission only with postoperative chemotherapy. All children are disease-free with a median follow-up of 30.5 months (range: 1+ to 50+). This intensive treatment was effective in both standard- and high-risk unresectable NB. However, whether a less intensive approach and fewer courses can also give similar results in standard-risk cases warrants further study.

Deferoxamine followed by cyclophosphamide, etoposide, carboplatin, thiotepa, induction regimen in advanced neuroblastoma: preliminary results. Italian Neuroblastoma Cooperative Group.

Based upon phase I and II studies of deferoxamine alone and in combination with cytotoxic agents cyclophosphamide, etoposide, carboplatin, and thiotepa (D-CECaT), we initiated a single arm multicentre trial in 1992 for advanced neuroblastoma. 57 of 65 patients who entered the trial were evaluable. Following 4 courses of the D-CECaT, almost all the patients underwent surgery. Toxicity was moderate and mainly reversible myelosuppression. The post-surgically defined responses in stage 3 high risk, stage 4 moderate risk and stage 4 high risk patients included 24 complete responses, 26 partial responses, and 3 minor responses, and 4 patients had progressive disease. These patients are being followed to determine the impact of this programme on their overall survival.

[Relapse modalities in medulloblastoma]. / Modalità delle recidive nel medulloblastoma.

We evaluated the modality of relapse and progression of medulloblastoma in 45 patients observed between 1981-1991. Children aged over 2 years were treated with surgery and postoperative radio-chemotherapy; among 12 children younger than 2 years, 8 were treated with surgery and chemotherapy and 4 with postoperative irradiation of remaining tumor. Cerebrospinal fluid shunting system was placed in 32 patients (71.1%). Patients were organized into three groups: group I (25 cases) = total tumor removal; group II (11 cases) = subtotal tumor removal; group III (9 cases) = partial tumor removal. 22 children died (48.8%: 10 of group I; 7 of group II; 5 of group III) at variable time interval from the operation during the following period. Among 23 alive patients, 3 are surviving with recurrence and progression of disease (all of group I), 20 are disease-free (44.4%: 12 of group I; 4 of group II; 4 of group III). Average postoperative follow-up period: 6 years for group I/II and 2 years for group III. Even if disease-free children are those treated by total-subtotal surgical removal (while local relapse occurs principally in patients treated by partial surgical resection: 44.4% of local relapse vs 12% of group I and 27% of group II), extensive surgery does not exclude possibility of metastatic localization in cerebrospinal axis, that occurs in 1/5-1/6 of all the patients without differences in each group. CSF shunting system did not cause extraneural metastases in our patients. We obtained long term survival rates or apparent recovery in almost 50% of cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Peripheral blood stem cells in children with solid tumors. Part II. Immunocytologic detection of tumor cells in bone marrow and peripheral blood stem cell harvests.

Simultaneous comparative assessment of tumor contamination in bone marrow aspirates and peripheral blood stem cell collections using immunocytochemical techniques was done in 6 children with neuroectodermal tumors. In 3 neuroblastoma patients tumor cells were detected in 5 of 16 marrow samples but not in peripheral blood stem cells. Clonogenic tumor cell reinfusion in the autologous support setting may be avoided in neuroblastoma patients by using peripheral blood stem cells.