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Biomedical subjects

R J Packer

Publications and source records attributed to R J Packer.

At least 37 records · Page 2Linked to original sources
PubMed1990

Hyperfractionated radiotherapy for children with brainstem gliomas: a pilot study using 7,200 cGy.

Brainstem gliomas, constituting approximately 10% of all childhood central nervous system tumors, remain the most resistant of all brain tumors to therapy. A subgroup of high-risk patients with tumors that diffusely involve the brainstem or that microscopically demonstrate foci of anaplasia on biopsy specimens rarely survive after treatment. Conventional doses of radiotherapy result in temporary clinical improvement in the majority of these high-risk patients; however, few if any remain alive 18 months after treatment. Hyperfractionated radiotherapy, with delivery of larger numbers of smaller fractions of radiotherapy, is a possible way to increase tumor control without increasing neurological toxicity. In 1985, a multiinstitutional phase I/phase II trial, using 100 cGy of radiation therapy twice daily to a total dose of 7,200 cGy, was undertaken for patients with high-risk brainstem gliomas. At the time of writing, 24 (69%) had developed progressive disease and 11 remained in continuous progression-free remission. Actuarial progression-free survival at 20 months is approximately 30%. Twenty-three of 31 evaluable patients had an objective radiographic response to therapy. In comparison to both historical control patients and patients treated in a previous trial using 6,480 cGy of hyperfractionated radiation therapy, there was a statistically significant improvement in progression-free survival rate for patients treated with 7,200 cGy of hyperfractionated radiation therapy (p less than 0.01). To date no patient has died as a result of treatment. Six patients developed transient neurological deterioration or cystic intralesional changes, as demonstrated on magnetic resonance imaging, within 6 weeks of the completion of radiotherapy. Postmortem examination performed in 7 patients did not disclose significant radiation necrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Chemotherapy for medulloblastoma/primitive neuroectodermal tumors of the posterior fossa.

Chemotherapy has only marginal efficacy in adult malignant brain tumors. In contrast, drug therapy is considerably more effective in medulloblastoma/primitive neuroectodermal tumors (MB/PNET) of the posterior fossa, the most common childhood primary central nervous system tumor. At the time of disease recurrence, a variety of different single agents and drug combinations result in tumor shrinkage and increased survival. The addition of chemotherapy to standard radiotherapy improves the rate and length of disease-free survival for those children with MB/PNET who have the most extensive tumors at diagnosis. It remains to be determined which drug or drug combinations are the most effective in MB/PNET, and which patients are most likely to benefit from chemotherapy. Chemotherapy may be useful to reduce or, in selected cases, obviate the need for radiotherapy and reduce treatment-related sequelae.

Antineoplastic Agents↗
PubMed1990

Pediatric brainstem glioma. Post-radiation clinical and MR follow-up.

Thirty-four pediatric patients, twenty with presumed and fourteen with biopsy or autopsy proven brainstem gliomas were imaged by CT and MR before radiation therapy. Twenty-eight patients received radiotherapy. Of these, eighteen fit the protocol for combined clinical and MR post-treatment evaluation. No cases of radionecrosis were seen at autopsy. This study shows that MR can demonstrate tumor response to radiation therapy, tumor progression prior to clinical deterioration, post-treatment cyst formation and hemorrhage. Although MR clinical correlation was not optimal on six week post-treatment evaluation, 4-10 month post-treatment MR scanning correlated well with clinical evaluation. MR appears useful in post-therapeutic monitoring of tumor response.

Adolescent↗
PubMed1990

Intracranial ependymomas in children.

Between 1970 and 1988, 51 children with intracranial ependymal tumors (33-infratentorial, 18-supratentorial received initial treatment at the University of Pennsylvania. Therapy consisted of total or near total tumor resection in 15 patients and partial resection or biopsy in 36. Postoperative irradiation alone was given to 18, chemotherapy to 4, and a combination of these two modalities to 26. Patients have been followed for a median period of 7.75 years. The 5-year actuarial survival and progression-free survival (PFS) rates are 46% and 30%, respectively. Of the 30 patients who have progressed, 29 did so locally and one died before the site of failure could be determined. Six patients also had disease outside the primary site at relapse; three of them had received craniospinal irradiation. Local control was significantly better for patients whose tumor dose exceeded 4500 cGy (32% vs. 0%, p = .01) and for Caucasian patients (34% vs. 15%, p =.05). Survival was better for patients who were over 4 years of age at diagnosis (55% vs. 30%, p = .04), for patients who received local radiation doses above 4500 cGy (51% vs. 18%, p = .01), and for Caucasian patients (43% vs. 14%, p = .01). Extent of resection, histology, location, the use of cranial or craniospinal irradiation, and the use of chemotherapy did not significantly impact on survival. We conclude that the inability to control local disease remains the single most important factor leading to treatment failure. Older age, higher local radiation dose, and Caucasian race appear to be the only favorable prognostic factors.

Adolescent↗
PubMed1990

Heterogeneity of clinical severity and molecular lesions in Aicardi syndrome.

All patients with Aicardi syndrome are female or have a 47,XXY karyotype. This finding, along with a report of an Aicardi syndrome patient with an Xp22/autosome translocation, led to the hypothesis that Aicardi syndrome might be caused by an X-linked dominant, male-lethal mutation on the short arm of the X chromosome. To study this hypothesis, we investigated X chromosome inactivation patterns in peripheral lymphocytes from seven patients. We used two methods: methylation-sensitive restriction enzyme analysis and segregation of the active X chromosome in somatic cell hybrids. We found that three of seven cytogenetically normal girls with Aicardi syndrome had profoundly skewed X-inactivation in their lymphocytes, supporting the concept that Aicardi syndrome is X linked. Three of the five girls with the greatest degree of psychomotor retardation and the poorest seizure control had skewed X-inactivation. In contrast, the two highest-functioning children had random X-inactivation. We screened DNA using eight polymorphic probes from the Xp22 region but were unable to identify a deletion in any of the seven patients. Nonrandom X-inactivation in lymphocytes and possibly other tissues in some, but not all, patients with Aicardi syndrome may reflect heterogeneity of their molecular lesions.

Agenesis of Corpus Callosum↗
PubMed1990

Localized 31P magnetic resonance spectroscopy of large pediatric brain tumors.

Fourteen children aged 1 week to 16 years, with a variety of large or superficial brain tumors, underwent localized in vivo 31P magnetic resonance spectroscopy of their tumor. Quantitative spectral analysis was performed by measuring the area under individual peaks using a computer algorithm. In eight patients with histologically benign tumors the spectra were considered to be qualitatively indistinguishable from normal brain. The phosphocreatine/inorganic phosphate ratio (PCr/Pi) averaged 2.0. Five patients had histologically malignant tumors; qualitatively, four of these were considered to have abnormal spectra, showing a decrease in the PCr peak. The PCr/Pi ratio for this group averaged 0.85, which was significantly lower than that seen in the benign tumor group (p less than 0.05). No difference between the two groups was seen in adenosine triphosphate or phosphomonoesters. It is concluded that a specific metabolic "fingerprint" for childhood brain tumors may not exist, but that some malignant tumors show a pattern suggestive of ischemia.

Adenosine Triphosphate↗
PubMed1990

Monosomy 22 in rhabdoid or atypical tumors of the brain.

Cytogenetic studies of three rare childhood brain tumors were performed. Two children presented with pure rhabdoid tumors. The third child had a tumor composed of a mixture of rhabdoid elements with neuroepithelial, epithelial, and mesenchymal tissue - an atypical teratoid tumor. All three tumors demonstrated monosomy 22 as the only cytogenetic abnormality. The cytogenetic findings suggest that loss of a gene or genes on chromosome 22 may be involved in the initiation or progression of these malignant tumors. Further studies on additional fresh tumor specimens are warranted; however, it is possible that cytogenetic studies may be used as an additional means of diagnosing rhabdoid or atypical teratoid tumors of the brain.

Brain Neoplasms↗
PubMed1990

Medulloblastomas.

It is obvious that the past decade has witnessed considerable progress in the management of children with medulloblastoma. Better surgical technique has led to more aggressive surgery with less morbidity. The use of staging has led to reduction in radiation therapy doses in some patients and will, it is hoped, lead to better neuropsychological outcome. The use of adjuvant chemotherapy in high-risk patients is delaying recurrence. It remains unknown, however, whether the patient with a medulloblastoma is ever "cured." Certainly, in the future, control of this tumor will depend on new therapeutic modalities, which will be developed on the basis of a better understanding of the biology of these primitive tumors. A better understanding of tumor immunology, cytogenetics, and biochemistry is a goal for the future.

Adolescent↗
PubMed1990

Primitive neuroectodermal tumors of the central nervous system. Patterns of expression of neuroendocrine markers, and all classes of intermediate filament proteins.

Snap-frozen samples from 22 primitive neuroectodermal tumors (PNETs) primary in the central nervous system were studied with antibodies to synaptophysin, bombesin, somatostatin, substance P, vasoactive intestinal polypeptide, all classes of intermediate filaments, and desmoplakins I and II. Frozen sections were immunostained by the avidin-biotin peroxidase complex and indirect immunofluorescence microscopy methods. Selected cases were also studied by double and triple label immunofluorescence microscopy, and by two-dimensional gel electrophoresis and immunoblot analysis. We found that all 22 PNETs expressed synaptophysin extensively. Focal expression of 2 or more neuropeptides was noted in 10 samples studied. All PNETs expressed vimentin, 21 of 22 expressed glial filament protein (GFP), 16 of 22 expressed neurofilament proteins (NFP), 4 of 22 expressed desmin, and 3 of 22 expressed cytokeratins. In only one case were focal and questionable reactions with desmoplakin antibodies seen. Immunoblots confirmed the presence of desmin. Double and triple immunofluorescence revealed a number of antigenic coexpressions in individual cells including: synaptophysin with vimentin, GFP, NFP and desmin, vimentin-GFP, vimentin-NFP, vimentin-cytokeratin, vimentin-desmin and desmin-NFP; similarly, combinations of vimentin-GFP-NFP, vimentin-GFP-desmin, and vimentin-GFP-cytokeratin were found. The consistent expression of synaptophysin and 2 or more neuropeptides indicates that central nervous system PNETs have significant phenotypic features in common with neuroendocrine tumors. Their complex and variable intermediate filament complement patterns combined with their consistent expression of specific neuroendocrine differentiation markers, suggest that central nervous system PNETs comprise a distinct, albeit heterogeneous group of neoplasms.

Adolescent↗
PubMed1990

Acute mental status changes in children with systemic cancer.

Acute changes in mental status (AMS) develop in children with cancer from a multitude of cancer- and treatment-related complications. To determine the incidence, etiology, and outcome of children with cancer who had AMS, the medical records of all children under 18 years of age with systemic cancer (excluding primary central nervous system tumors) who had AMS in our institution during the years 1981 through 1987 were reviewed. AMS developed in 89 of 815 children at risk (11%). The AMS was caused by seizures in 53 (60%), an encephalopathy in 24 (27%), and a stroke syndrome in 12 (13%). AMS occurred in 42 of 305 (14%) with leukemia, 16 of 139 (12%) with lymphoma, 14 of 136 (10%) with sarcoma, 10 of 104 (9%) with neuroblastoma, and 7 of 104 (5%) with other malignancies. Children with acute lymphocytic leukemia were more prone to having seizures (61%), while children with nonacute lymphocytic leukemia were almost equally likely to have encephalopathies, strokes, or seizures. Children with lymphoma were admitted for treatment most often with an encephalopathy (44%). Etiologies for AMS were evaluated vigorously, and one or more etiologies were identified in 80 of 89 (89%) patients. Dependent on the type of tumor, the anticancer treatment used and, timing during the course of illness AMS occurred, specific diagnoses were more likely. Neurologic morbidity and mortality were dependent on the cause of AMS. Children with seizures that were initially difficult to control were more likely to require long-term anticonvulsant therapy.

Acute Disease↗
PubMed1989

Neurologic complications in children with soft tissue and osseous sarcoma.

From 1980 to 1987, 162 consecutive children with soft tissue and osseous sarcoma were reviewed to determine the frequency and types of neurologic complications seen. Neurologic complications occurred in 43 of 162 (26.5%) patients. Children with poorly differentiated sarcomas and rhabdomyosarcoma were more likely to have neurologic complications, which occurred in 39% of patients at risk. The types of complications seen included: metastatic spinal cord compression (11%); symptomatic peripheral neuropathy (10%); intracranial metastatic disease (7.5%); seizures (6%); and acute and chronic methotrexate-related neurologic dysfunction (2.5%). Spinal cord compression frequently occurred early in disease whereas brain metastases was almost always a late finding. Symptomatic peripheral neuropathy occurred primarily in children with rhabdomyosarcoma and Ewing's sarcoma. The advent of increasingly successful therapies for children with sarcoma and the frequency of severe neurologic complications indicate that a heightened level of surveillance for neurologic compromise is required.

Adolescent↗
PubMed1989

Phase I trial and pharmacokinetic evaluation of fazarabine in children.

A phase I trial of fazarabine (1-beta-D-arabinofuranosyl-5-azacytosine, NSC 281272) administered as a 24-h continuous infusion was performed in 16 children with refractory malignancies. Dose-limiting toxicity consisting of reversible granulocytopenia and thrombocytopenia was observed in 4 of 4 solid tumor patients treated at the starting dose of 20 mg/m2/h. Subsequent patients were treated at a dose of 15 mg/m2/h which was determined to be the maximum tolerated dose. Moderate nausea and vomiting were the only other toxicities observed. Plasma steady-state concentrations of fazarabine were attained by 2-4 h in all patients and were 1.8 and 2.5 microM at the 15- and 20-mg/m2/h doses, respectively. The total body clearance of fazarabine was 571 and 550 ml/min/m2 at the 15- and 20-mg/m2/h doses, respectively. In three of four patients evaluated, fazarabine was detectable in the cerebrospinal fluid (CSF). Steady-state CSF concentrations ranged from 0.29 to 0.74 microM in these three individuals and the steady-state CSF:plasma ratios ranged from 0.22-0.25. Both the plasma and CSF steady-state concentrations were within the 0.1 to 1 microM range reported to be cytotoxic in vitro against the Molt-4 human T-lymphoblastic leukemia cell line. Based on the above, the optimal dose for phase II trials of fazarabine administered as a 24-h infusion is 15 mg/m2/h (360 mg/m2/day).

Antimetabolites, Antineoplastic↗
PubMed1989

Phase I and pharmacokinetic evaluation of thiotepa in the cerebrospinal fluid and plasma of pediatric patients: evidence for dose-dependent plasma clearance of thiotepa.

A Phase I trial of thiotepa (TT) administered as an i.v. bolus was performed in 19 children with refractory malignancies. The starting dose was 25 mg/m2 with escalations to 50, 65, and 75 mg/m2. Seven additional patients were treated with 8-h infusions at 50 or 65 mg/m2. The maximum tolerated bolus dose was 65 mg/m2. Reversible myelosuppression was the dose-limiting toxicity. The plasma and cerebrospinal fluid (CSF) pharmacokinetic parameters of TT and its major active metabolite tepa (TP) were also evaluated. When the bolus or infusion methods of TT administration were compared, there was little difference observed in any pharmacokinetic parameter for either TT or TP. The plasma disappearance of TT was rapid and biphasic with half-lives of 0.14 to 0.32 and 1.34 to 2.0 h. Dose-dependent pharmacokinetics was demonstrated by steadily declining plasma clearance with increasing TT dose. Clearance values declined from 28.6 liters/m2/h at the 25-mg/m2 dose to 11.9 liters/m2/h at the 75-mg/m2 dose. The half-life of TP was longer than that of TT and ranged between 4.3 and 5.6 h. There was evidence of the saturation of TP production. TT and TP both exhibited excellent penetration into the CSF, producing lumbar and ventricular concentrations which were nearly identical to simultaneous plasma concentrations. In one patient with a Rickham reservoir, the CSF:plasma area under the (concentration x time) curve ratios for TT and TP were 1.01 and 0.95, respectively. The above data indicate that TT can be safely administered to pediatric patients at doses higher than conventionally used. The favorable CSF penetration of TT and TP suggests that Phase II studies of TT be considered in patients with central nervous system tumors.

Adolescent↗
PubMed1989

Suprasellar germinomas in childhood. A reappraisal.

Germinomas in childhood may arise in both the suprasellar and pineal region, and outcome has been reported to be worse for suprasellar germinomas with a 5-year survival rate of 20% as compared to 60% for pineal germinoma. To determine the factors impacting on outcome, the results of a uniform treatment approach were evaluated and included primary surgical debulking (PSD) and systemic craniospinal axis radiation (CSRT) for suprasellar germinomas. Between 1976 and 1985 ten consecutive patients (seven females, three males) with the pathologically confirmed diagnosis of suprasellar germinoma were treated. Outcome was compared to four male patients with pineal germinoma treated over the same time period and series of patients reported in the literature. At diagnosis the mean age of patients with suprasellar germinoma was 13.9 years (range, 8.9 to 9.4 years). Symptoms were present for a mean of 18 months (range, 2 to 72 months) prior to diagnosis and included diabetes insipidus, anterior pituitary dysfunction, decreased vision, headache, vomiting, and diplopia. Staging studies, including myelography (n = 4) and cerebrospinal fluid cytology (n = 7), disclosed dissemination in only one child. Surgical treatment included biopsy in three cases, partial resection in five, and total resection in two; no permanent postsurgical complications were noted. The mean radiation therapy dose to the tumor site was 4953 cGy (range, 4400 to 5250 cGy) and to the spine 3354 cGy (range, 3000 to 4000 cGy). Patients were followed for a mean period of 5.1 years (range, 1.9 to 10.5 years). One patient with SG who did not receive treatment initially developed a pineal tumor after diagnosis; she was treated with PSD and CSRT and is asymptomatic 5 years later. All the remaining patients are alive and remain disease-free. Surgical resection and CSRT results in excellent disease control for children with suprasellar germinomas, and outcome is similar to those patients with pineal germinoma.

Adolescent↗
PubMed1989

Clinical, cytogenetic, and pedigree findings in 18 cases of Aicardi syndrome.

Eighteen girls with Aicardi syndrome were identified through a survey of neurologists, geneticists, and ophthalmologists. All had infantile seizures, developmental delay, agenesis of the corpus callosum (complete: 72%, partial: 28%), and characteristic chorioretinal lacunar lesions. Costovertebral defects including hemivertebrae, scoliosis, and absent or malformed ribs were present in 39%, cortical heterotopias were present in 50%, and microphthalmia was identified in a third. Cytogenetic investigation was carried out in all families. An unbalanced X;3 translocation, 46,X,der(X)t(X;3)(p22.3;p23)mat, was discovered in a girl with chorioretinal lacunar lesions characteristic of Aicardi syndrome, developmental delay, and infantile seizures. However, this child had a normal appearing corpus callosum on CT and magnetic resonance imaging scans and therefore did not meet the criteria for inclusion in the study. Chromosomes of all other patients and parents were normal. Findings at birth, age of seizure onset, treatment, and prognosis are discussed. The pedigree data from these 18 families demonstrated an unaffected male:female sib ratio of 1:1.7 and a 14% spontaneous abortion rate. The findings of this study support the contention that Aicardi syndrome is an X-linked dominant disorder with early embryonic lethality in hemizygous males and that all cases represent new mutations.

Abnormalities, Multiple↗
PubMed1989

Isochromosome 17q in primitive neuroectodermal tumors of the central nervous system.

We have prepared karyotypes from 22 primitive neuroectodermal tumors (PNETs) from pediatric patients ranging in age from 10 months to 16 years. Twenty-one cases were newly diagnosed, primary, posterior fossa tumors. One case was a recurrent tumor in a patient previously treated with radiation. Cytogenetic results were obtained from direct preparations and/or short-term (1-10 day) culture. Three tumors had apparently normal karyotypes. Nineteen tumors demonstrated numerical and/or structural abnormalities. The most frequent structural chromosomal changes were deletions and nonreciprocal translocations. Four tumors contained double minutes. Several chromosomes appear to be nonrandomly involved in PNETs. These include chromosomes 5, 6, 11, 16, 17, and a sex chromosome. The most consistent change, however, was an i(17q), present in one-third (8/22) of the cases. Strikingly, in three of these eight tumors, the i(17q) was the only structural abnormality observed. An i(17q) is not specific for pediatric PNETs, as it is also seen in leukemias and other solid tumors. However, in PNETs it may be a primary change related to tumor development and/or progression. Clinically, there was no correlation of the cytogenetic findings with histologic features of the tumors, size of the tumor, extent of metastasis, or surgical resection.

Adolescent↗
PubMed1989

An animal model to detect the neuropsychological toxicity of anticancer agents.

The unexpected discovery that certain chemotherapeutic agents used in the treatment of childhood cancers have neurocognitive side effects has prompted a search for techniques that identify those medications that place children at risk. An animal model for the assessment of resultant neurocognitive toxicity is described which makes use of simple classical conditioning. We have shown that rats learn about environmental events more slowly following neonatal administration of methotrexate. The changes after methotrexate exposure are not related to stimulus characteristics or to perceptual abilities, but rather to damage to the neural systems involved in acquisition, retention, or recall. Similar problems with learning have been observed in children treated with methotrexate. An effective animal model such as the one described here may help detect and avoid antineoplastic agents that produce severe cognitive defects in childhood cancer patients.

Animals↗