Structuring a safer donor-replacement program

BACKGROUND

Replacement donors are more likely than volunteer donors to have positive or abnormal tests for transfusion-transmissible disease. In an effort to increase the donor pool, workers sought to identify a safer replacement-donor subgroup that may be acceptable for routine donations.

STUDY DESIGN AND METHODS

In a retrospective review and cohort study, the replacement-donor effect was separated from the new-donor effect. The relative effect the replacement donor has on the risk of transfusion-transmissible diseases, donor retention, and frequency of returning donations was then quantified by comparison against the effect of repeat volunteer donors.

RESULTS

The replacement donor had 3.1 times the risk and 0.72 times the donor retention rate and made 0.81 times as many returning donations as the repeat volunteer donor. The figures for the new-donor effect were similar. The two risks were additive, making a new replacement donor particularly hazardous. If replacement donations only from repeat replacement donors were considered, the donor risk and the number of donations per returning donor were made comparable to those for the general (combined) volunteer donor.

CONCLUSION

The negative effect of the replacement donor is similar in magnitude to that of the new volunteer donor. A replacement-donation program targeting repeat replacement donors has an acceptable risk profile and may be a valuable adjunct to the collection of blood from general volunteer donors.

Unusual features of the Drosophila melanogaster telomere transposable element HeT-A are conserved in Drosophila yakuba telomere elements

HeT-A was the first transposable element shown to have a bona fide role in chromosome structure, maintenance of telomeres in Drosophila melanogaster. HeT-A has hallmarks of non-long-terminal-repeat (non-LTR) retrotransposable elements but also has several unique features. We have now isolated HeT-A elements from Drosophila yakuba, showing that the retrotransposon mechanism of telomere maintenance predates the separation of D. melanogaster and D. yakuba (5-15 million years ago). HeT-A elements from the two species show significant sequence divergence, yet unusual features seen in HeT-Amel are conserved in HeT-Ayak. In both species, HeT-A elements are found in head-to-tail tandem arrays in telomeric heterochromatin. In both species, nearly half of the HeT-A sequence is noncoding and shows a distinctive imperfect repeat pattern of A-rich segments. Neither element encodes reverse transcriptase. The HeT-Amel promoter appears to be intermediate between the promoters of non-LTR and of LTR retrotransposons. The HeT-Ayak promoter shows similar features. HeT-Amel has a frameshift within the coding region. HeT-Ayak does not require a frameshift but shows conservation of the polypeptide sequence of the frameshifted product of D. melanogaster.

[Development of an electrode for atrial epicardial mapping]

Procedure of a electrode for atrial epicardial mapping (template electrode) is introduced in this paper. It is easy to made, we can get sharp and clear waveforms and a constant baseline while mapping. If the electrode is connected with computer, it is able to be used for epicardial mapping of atrial arrhythmias, especially atrial fibrillation in real time.

The internal ribosomal entry site of the encephalomyocarditis virus enables reliable coexpression of two transgenes in human primary T lymphocytes

It is essential for the improvement of adoptive cell therapies to generate efficiently large populations of human primary T cells that reliably express a suicide gene conferring drug sensitivity, such as herpes simplex virus thymidine kinase (HSVtk). We show here that an optimized dicistronic vector containing the encephalomyocarditis virus (EMCV) internal ribosomal entry site (IRES) is functional in human primary. T lymphocytes that bear on average one integrated vector copy per cell. We demonstrate reliable coexpression of the marker NTP, an inactive mutant of the human low-affinity nerve growth factor receptor and HSVtk. In the dicistronic vector NIT, NTP is expressed as a cap-dependent marker and HSVtk as a nonselectable IRES-dependent gene. Cell-surface expression of NTP is sufficient to allow for the efficient and rapid enrichment of the transduced cells to high purity. Of these purified lymphocytes, 97 +/- 4% and 92 +/- 6% are selectively eliminated when cultured in the presence of 1.0 or 0.1 microM ganciclovic respectively, establishing that the EMCV IRES ensures efficient and sufficient expression of two genes in human primary T cells.

Recombinant retroviruses pseudotyped with the vesicular stomatitis virus G glycoprotein mediate both stable gene transfer and pseudotransduction in human peripheral blood lymphocytes

It is essential for the study of T-cell function and the improvement of adoptive cell therapies to efficiently generate large populations of human primary T cells that reliably express foreign genes. This goal is achieved by using recombinant retroviruses pseudotyped with either the gibbon ape leukemia virus (GaLV) envelope or the vesicular stomatitis virus G (VSV-G) glycoprotein. We show here that both retroviral particles mediate stable gene transfer in CD4+ and in CD8+ peripheral blood lymphocytes cultured under optimized conditions. However, VSV-G-pseudotyped virions may cause transduction artifacts that must be carefully excluded. The VSV-G virions require 10- to 100-fold higher concentrations of infectious particles to achieve levels of gene transfer comparable to GaLV-virions. Nonetheless, the physical stability of VSV-G-coated particles enables the concentration of viral stocks to 10(9) infectious particles per milliliter or more.

Molecular cloning and characterization of a new receptor for galanin

Galanin (GAL) is a widely distributed neuropeptide with diverse biological effects including modulation of hormone release, antinociception and modification of feeding behavior. Its effects are mediated through G-protein-coupled receptors (GPCR) for which only a single type has been cloned, GAL receptor 1 (GALR1). We describe the cloning of a second galanin receptor type, GALR2, from rat hypothalamus. The GALR2 amino acid sequence is 38% identical to GALR1 and is pharmacologically similar to GALR1 when expressed in COS-7 cells. GALR2 is encoded by a single gene containing at least one intron and expressed in a diverse range of tissues.

[Kaposi's sarcoma associated with HIV in otorhinolaryngology: report of 21 cases]

Twenty one cases of kaposi's sarcoma (KS) with manifestation in the field of otolaryngology are reported. The incidence of KS is increasing following epidemic of AIDS all over the world. Epistaxis, nasal obstruction, sore-throat, dry of foreign body filling in throat and nodal mass are most frequent manifestation. The relationship of KS with HIV, it's pathology and diagnosis are discussed.

[CT for diagnosis of parathyroid adenoma]

We analyzed Ct findings of 10 cases with parathyroid adenoma which had been verified by surgery and pathologic section. The correct localization of 9 adenomas was made by CT preoperatively. The method of CT scanning of parathyroid adenoma were elucidated. The results showed that most adenomas were located in the groove between trachea and esophagus. The contour of tumors was oval, the edge was smooth and regular. Enhancement CT images were helpful for differentiating the tumor from blood vessel. It is indicated that CT scanning is a good method for localizing the parathyroid adenoma.

Trabeculectomy--success rates in a Singapore hospital

Previously published papers on the success of trabeculectomy as a treatment for glaucoma show success rates between 67% and 84%. The success rate of trabeculectomy in Afro-Carribean patients was observed to be lower than in Caucasian patients. It has been commonly believed that the success rate of trabeculectomy in Oriental/Asian eyes would lie somewhere between these. We reviewed the records of 51 consecutive trabeculectomies performed in the National University Hospital, Singapore and found that our success rate was lower-43.1% overall and 48.7% for primary glaucomas.

Growth and final height after treatment for childhood Hodgkin disease

PURPOSE

To evaluate in children the impact of contemporary treatment for Hodgkin disease on the pattern of growth and final height.

PATIENTS AND METHODS

We studied 80 patients (54 males) aged <14 years at diagnosis, with newly diagnosed, pathologically confirmed Hodgkin disease, treated at a single institution. Forty six patients received chemotherapy (CT) + radiotherapy (RT), 23 patients received RT alone, and 11 patients received CT alone. Heights were obtained at diagnosis, at the end of treatment, 1, 2, and 3 years after the end of treatment and at attainment of final height. Heights were converted to age- and sex-adjusted SD scores (SDS).

RESULTS

There was a significant change in height SDS at the end of treatment compared to height SDS at diagnosis for all three groups (CT + RT: -0.33, p<0.001; RT: +0.09, p=0.027; CT: -0.24, p=0.012). Over the 3 years following treatment, the rate of change of height SDS was not statistically different between the three treatment groups. Final height SDS was decreased for patients receiving RT + CT (-0.41 SDS, p=0.02; n=31). The change in final height SDS for patients receiving RT or CT only was -0.36 (n=14) and +0.42 (n=4), respectively. Loss of final height SDS correlated with younger age at diagnosis (p=0.005). Patients receiving higher RT doses tended to fare worse (p=0.08).

CONCLUSIONS

Pediatric patients treated for Hodgkin disease with the combination of RT and CT suffer a small but significant decrease in their final height SDS. Younger patients and those treated with higher RT doses appear to experience the greatest loss of height potential.

412-positive mesodermal cells and the gonadal mesoderm are separate from the fat-cell lineage

The Drosophila retrotransposon, 412, is expressed in a cell-specific manner during embryogenesis. At stage 11, 412 transcripts are present in bilateral clusters of cells within the mesoderm. The posterior clusters of 412-positive cells become associated with the gonads at stage 13; however, the fate of the cells in the remaining clusters is unknown. We have tested by in situ hybridization to whole-mount embryos the possible identity of these cells with known precursor cell types present in bilateral clusters. We simultaneously located the 412-positive cells and the precursor cells to visceral muscle or the fat body. We have determined that the 412-positive cells do not correspond to these precursor cells and that the development of the visceral muscle or fat body does not affect the expression of 412 during embryogenesis.

Mechanism and structure based inhibitors of phospholipase C enzymes

PI-specific PLC enzymes are a key component of phosphatidylinositol-mediated signaling pathways since the hydrophobic product, diacylglycerol, activates protein kinase C and the water-soluble product, inositol trisphosphate, is involved in Ca2+ mobilization. Nonspecific, or PC-PLC, enzymes can generate diacylglycerol without Ca2+ mobilization. A series of inhibitors, both lipophilic and water-soluble, have been synthesized to target each of these two classes of PLC enzymes. Design of the inhibitors was based on proposed enzyme mechanisms and available crystal structures. The solution conformations of the lipophilic phospholipid analogs, (diheptanoylphosphatidyl(2-O-methyl)inositol for PI-PLC and a dihexanoyl-sn-(3-N-benzylaminoglycero)phosphoramidocholine for PC-PLC, have been determined using NMR methodology and the interaction of these compounds with bacterial enzymes has been examined. Water-soluble inhibitors include strained cyclic phosphonates for PI-PLC and vanadate for PC-PLC. An eventual goal of this work is to generate compounds that specifically target each type of intracellular PLC activity.

Paediatric pacemaker implant using the transvenous endocardial approach

The advent of the pacemaker has opened a whole new dimension to management in cardiology. Although its use has been well described in adults, its role in paediatric cardiology has proven to be equally exciting and challenging. We describe a case of a child with complex cyanotic heart disease who had an insertion of a cardiac pacemaker via the transvenous route, one of the youngest to be performed locally. This article also highlights the pertinent features of paediatric pacemaker therapy, including its indications and implantation technique.

Amplification of the dihydrofolate reductase gene is a mechanism of acquired resistance to methotrexate in patients with acute lymphoblastic leukemia and is correlated with p53 gene mutations

Although dihydrofolate reductase (DHFR) gene amplification is a common mechanism of resistance to methotrexate (MTX) in tumor cell lines, with the exception of a few case reports, the incidence of this phenomenon as a mechanism of MTX resistance in the clinic has not been reported. We studied 38 untreated patients and 29 patients in relapse with acute lymphoblastic leukemia (ALL) for gene amplification and p53 gene mutations. Three patients were studied both at diagnosis and at each of two relapses after treatment with MTX. Nine of 29 relapsed patients (31%) had low-level DHFR gene amplification (two to four gene copies) associated with increased levels of DHFR mRNA and enzyme activity. Of significance was a correlation of gene amplification with p53 mutations in seven of nine relapsed patients (P < .001). Low-level DHFR gene amplification may be an important cause of MTX resistance in ALL and strengthens the concept that mutations in the p53 gene may lead to gene amplification as a consequence of defective cell cycle control.

Lead-induced nephropathy: relationship between various biological exposure indices and early markers of nephrotoxicity

Lead nephropathy in adults is silent and insidious, characterized by the absence of proteinuria in its early phase. Of the early markers of nephrotoxicity, urinary N-acetyl-beta-D-glucosaminidase (NAG) appears to be the only one that is elevated in early lead nephropathy. However, the elevation in urinary NAG activity may be a response to a sharp increase in renal burden of lead. Its usefulness as a marker of chronic lead nephropathy is thus in doubt. There is a need, then, to identify a reliable early biological indicator of lead-induced kidney damage. Furthermore, there is also a need to identify suitable markers of chronic exposure to describe meaningful dose-response and dose-effect relationships. Traditionally, blood lead (PbB) was used, but the current blood lead level (PbBrec) is more an indicator of recent exposure. Time-integrated blood lead indices (PbBint) derived from repeated serial PbB measurements can be used as indices of chronic exposure. In 128 lead-exposed workers, the PbBint was the most important exposure variable in describing the variability in urinary alpha 1-microglobulin (U alpha 1 m), urinary beta 2-microglobulin (U beta 2m), and urinary retinol binding protein (URBP). U alpha 1m was the only marker that was significantly higher in the exposed group, with a good dose-response and dose-effect relationship with PbBint. The lack of dose-response and dose-effect relationships in other studies may be due to inappropriate exposure markers as well as less sensitive response markers. PbBint has a better correlation than PbBrec. Furthermore, U alpha 1m may be the most sensitive of the markers because of its higher molecular weight.

Cardiac failure and dysrhythmias 6-19 years after anthracycline therapy: a series of 15 patients

The clinical course of late symptomatic anthracycline cardiomyopathy, and resultant changes of cardiac function, were described in 15 patients. They represented a subset of 300 patients who had cardiac evaluations to identify the prevalence of late cardiotoxicity more than 4 years after anthracycline therapy in these patients. The clinical course and all available cardiac evaluations including electrocardiography, continuous taped electrocardiography, echocardiography, radionuclide cardiac angiography, cardiac catheterization, and endomyocardial biopsy, of the 15 patients were reviewed. The patients had received 285-870 (median 540) mg/M2 of daunorubicin and/or doxorubicin 6-19 (median 12) years prior to the onset of late symptoms. Seven patients also had 2,100-4,000 cGy mediastinal radiotherapy. Five patients had required treatment for cardiac symptoms at the end of chemotherapy but 10 patients had no cardiac problems anteceding their late decompensation. Fractional shortening on echocardiogram at late decompensation was 8-20% (median 17%) and radionuclide left ventricular ejection fraction was 8-59% (median 38%). All were treated with digitalis and diuretics and 13/15 with afterload reduction, with at least transient improvement of symptoms. They were followed for 1-9 (median 3) years after late decompensation. One died of uncontrollable cardiac failure. Another underwent successful cardiac transplantation. Conduction abnormalities and dysrhythmias were present in 14/15 patients and 3 died suddenly. Two more had syncope, one requiring an automatic cardiac defibrillator. Endomyocardial biopsy or autopsy revealed hypertrophy and fibrosis in 10/10 patients. Our patients with early cardiac symptoms improved transiently but decompensated later and patients with no early symptoms developed cardiac symptoms more than 10 years after anthracycline therapy. Therefore, patients who have received anthracyclines should have continued cardiac evaluation.

Glomerular function of lead-exposed workers

Among lead-exposed workers, there is evidence of increased mortality from chronic renal diseases (nephritis and nephrosis). Epidemiological studies using early markers of nephropathy among lead-exposed workers failed to demonstrate early renal changes. This study is aimed at assessing the glomerular function of 137 lead-exposed subjects and at evaluating whether changes in markers of glomerular function are related to exposure indices derived from longitudinal blood lead data. A control group of 153 postal workers was also investigated. Several exposure indices were derived for the exposed workers, including a time-integrated index Pb in blood (PbB)int and the number of times the PbB was above critical values (PbB400, PbB500, PbB600). Through multiple linear regression analysis, PbBint was the best predictor of variation in serum beta 2-microglobulin (S beta 2m) and alpha 1-microglobulin (S alpha 1m) and urinary albumin (UA1b). A small but statistically significant difference in the mean beta 2m was found. S beta 2m was also the only marker showing a significantly higher prevalence rate ratio (PRR) of abnormalities among lead-exposed workers. Though there was no clear dose-response relationship with PbBint as the index of dose, all the 15 subjects with abnormal S beta 2m in the older age group were found in the highest PbBint group. Furthermore, of the 8 subjects with low 4-h creatinine clearance (CrCl4h), 6 had abnormal levels of beta 2m. Two subjects with CrCl4h of less than 75 ml/min/1.74 m2 had high PbBint values, thus suggesting that high blood lead levels over a prolonged time may be associated with decreased CrCl4h. Though the long-term significance of elevated S beta 2m and UA1b is unclear, their association with high PbBint and decreasing CrCl4h indicate a potentially adverse effect. Their relationship with PbB400 and PbB600 suggests that the threshold of 700 micrograms/l for PbB may not prevent the occurrence of lead nephropathy.

Molecular characterization of a lipid-modified virulence-associated protein of Rhodococcus equi and its potential in protective immunity

Virulent strains of Rhodococcus equi produce plasmid-mediated 15- and 17-kDa proteins, which are thermoregulated and apparently surface-expressed. We demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) that R. equi produce three antigenically-related virulence-associated proteins, a diffuse 18-22-kDa, a 17.5-kDa and a 15-kDa protein. Phase partitioning of whole cells of R. equi strain 103 with Triton X-114 (TX-114) and labelling with [3H]-labelled palmitic acid showed that the two higher molecular weight proteins are hydrophobic and lipid modified. The 15-kDa protein did not partition into TX-114 and was not lipid modified. Cloning and expression of a fragment of the R. equi virulence plasmid in Escherichia coli showed that the three proteins were expressed from a single gene. Sequence analysis of this gene (designated vapA) revealed a 570-bp open reading frame encoding a polypeptide of 189 amino acids with a calculated molecular mass of 19,175 Da. The mature, nonlipid modified protein had a calculated mass of 16,246 Da. The 17.5- and 18-22-kDa forms of the protein are therefore due to lipid modification. No significant sequence homology of the vapA gene with other reported nucleotide sequences were found. Opsonization of virulent R. equi with an IgG1 mouse monoclonal antibody (MAb103) to the VapA protein significantly enhanced uptake in the murine macrophage cell line IC-21. Intraperitoneal injection of mice with Mab103 enhanced initial clearance from the liver of mice challenged intravenously with R. equi. Immunization of mice with the lipid-modified VapA purified by SDS-PAGE fractionation or with acetone precipitated VapA protein following TX-114 extraction resulted in significantly enhanced clearance from the liver and spleen following intravenous challenge. The VapA protein of R. equi appears therefore to be a protective immunogen.

Urinary excretion of tubular brush-border antigens among lead exposed workers

The brush-border of the human renal proximal tubule is extremely sensitive to toxic, ischaemic and inflammatory insults. A monoclonal antibody to a brush-border antigen (BB-50) had been shown to identify increased urinary excretion of BB-50 (UBB-50) among workers exposed to heavy metals and hydrocarbons as well as patients on cisplatin and patients with early diabetic nephropathy. This study describes the use of this antibody to quantify UBB-50 among lead exposed workers. The study population consisted of 154 workers from a factory manufacturing lead stabilisers. Of these 91 workers had less than 6 months of exposure and formed the control group. The remaining 63 workers with a median exposure of 3 years formed the exposed group. Several blood lead (PbB) indices were used as exposure indices. These include the most recent PbB (PbBrec), a time-integrated blood lead index (PbBint), an absolute change in recent PbB (PbB delta), a relative change in PbB (PbB delta%), as well as the number of times the PbB measurements were above 40, 50 and 60 micrograms/100 ml (PbB40, PbB50, PbB60 respectively). Urinary levels of beta-2-microglobulin (U beta 2m), alpha-1-microglobulin (U alpha 1m), retinol binding protein (URBP), albumin (UAlb), activity of total N-acetyl-D-beta-glucosaminidase (NAG-T) and heat stable NAG isoenzyme (NAG-B) were measured along with the serum beta 2m (S beta 2m). Through stepwise analysis, UBB-50 was best correlated with PbBint, PbB40 and PbB delta% (r2, 0.271). Of these, PbBint and PbB40 had about twice the contribution to the variation in UBB-50.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective transfer of cholesteryl ester over triglyceride by human plasma lipid transfer protein between apolipoprotein-activated lipid microemulsions

The substrate-specific rate of the human plasma lipid transfer protein (LTP) reaction was studied using pyrene-labeled substrate lipid analogues as probes for various lipids, by monitoring the ratio of the fluorescence intensities of their excimers to those of their monomers as an indicator of pyrene concentration in the microenvironment. Transfer of cholesteryl ester (CE) and triglyceride (TG) was demonstrated between human high-density lipoproteins, between low-density lipoproteins, and between these two lipoprotein, and the specific fractional transfer rate of CE was always higher than that of TG by a factor of 2.4-7.9. On the other hand, the transfer by LTP of CE, TG, and phosphatidylcholine (PC) was also demonstrated between lipid microemulsions having an average diameter of 25-26 nm using the same probes, but only when the emulsions were activated by apolipoproteins A-I, A-II, E, or C-III. The maximally activated rates of the transfer of CE and TG were the same when measured between the emulsions with cores composed exclusively of either lipid. The specific fractional transfer rate of pyrene-CE, however, was inversely proportional to the percentage of CE in the TG core of the emulsions, and the initial transfer of TG was almost completely inhibited by the presence of small percentages of CE in the TG core. Thus, the transfer of CE between the emulsions is highly selective over that of TG by orders of magnitude, much more selective than the reaction between any natural plasma lipoproteins, but this selectivity is not a rate-limiting step of the overall LTP reaction. The maximally activated LTP-catalyzed transfer rate of PC between the emulsions was somewhat higher than that of CE or TG and was not affected by the composition of the core lipids of the emulsion, TG or CE. When an excess amount of LTP was incubated with emulsion containing a small percentage of pyrene-CE in the TG core in the absence of the acceptor particles, excimer fluorescence rapidly decreased to the base line, and this change was suppressed when pyrene-CE was diluted with CE in the core. This result may indicate that LTP selectively disrupts pyrene-CE excimer formation on the basis of its selective interaction with the CE molecule over TG in the emulsion system as a putative background mechanism for the selective transfer of CE.

Urinary N-acetyl-beta-D-glucosaminidase activity in workers exposed to inorganic lead

Urinary N-acetyl-beta-D-glucosaminidase (NAG) had been shown to be a useful early marker of renal injury. In workers exposed to lead it seems to be the only early marker but the dose response and dose effect relations are weak. Furthermore, the significance and underlying mechanism of increased urinary NAG activity is far from clear. By studying the isoenzyme profiles of urinary NAG, the significance and underlying mechanism may be further clarified. The heat labile (NAG-A) and heat stable (NAG-B) isoenzyme profiles of 128 workers exposed to lead from a lead stabiliser factory were analysed. NAG activity was expressed as total NAG, NAG-A, and NAG-B activity as well as ratios (NAG-B/total NAG and NAG-B/NAG-A). Exposure indices included the recent concentration of blood lead (BPb), a cumulative blood lead index (TBPb), and the recent change in concentration of blood lead (CBPb). The NAG indices correlated best with CBPb. Nearly 50% of the variation in NAG-B activity could be explained by the combination of all three exposure indices but only the CBPb was highly significant. When these exposure indices were entered separately into the regression equation, CBPb accounted for 36.3% of the variation in NAG-B activity, 5.7% was accounted for by TBPb and 2.7% by BPb. There was also no dose-effect or dose-response relation between the NAG variables and BPb or TBPb groups. With CBPb, there were dose-effect and dose-response relations. With CBPb, there was an increase in NAG variables in the group with more than 25% increase in blood lead over the past six months. The increase in NAG activity in this study is likely to be due to a recent increase in concentration of blood lead and hence presumably a recent rise in renal burden of inorganic lead. This suggests that the increase in urinary NAG activity is a form of acute response to a sharp increase in renal burden of lead, rather than to a cumulative dose. Heat stable NAG is part of the lysosomal membrane and is present in the urine when there is breakdown of lysosomes. Our data therefore contradict suggestions that the increase in urinary NAG activity is due to exocytosis.

Development of a new intensive therapy for acute lymphoblastic leukemia in children at increased risk of early relapse. The Memorial Sloan-Kettering-New York-II protocol

BACKGROUND

Improved survival of children with acute lymphoblastic leukemia (ALL) has made it more difficult to develop new protocols to further improve results. The authors report the pilot experience with the Memorial Sloan-Kettering-New York-II (MSK-NY-II) protocol, based on the New York regimen with changes made in an attempt to improve efficacy while reducing toxicity.

METHODS

Forty-four of 46 consecutive patients were randomized to one of four regimens varying only in the sequence and mode of administration of the drugs during the first 48 hours of therapy, while the kinetics of the disappearance of the leukemic cells from the bone marrow was monitored with bone marrow aspirates and biopsies on days 0, 2, 7, and 14.

RESULTS

Thirty-two high-risk and 12 average-risk patients were randomized. The marrow contained less than 25% blasts in 74.4% and 92.9% by day 7 and 14, respectively. Ninety-three percent achieved remission. Regimens beginning with daunorubicin achieved a greater and more rapid reduction in leukemic cells than those starting with cyclophosphamide. Daunorubicin infusion produced a more rapid cytoreduction than daunorubicin bolus. Two of 41 patients who achieved remission relapsed, and there was one death in remission. With a median follow-up of 54+ months, the event-free survival (EFS) rate was 86% +/- 10%. Disease-free survival (DFS) rate at 48 months was 93%. The estimated 4-year EFS rate for the high-risk and average-risk patients were 83 +/- 14% and 93 +/- 10%, respectively. Four of 18 patients given daunorubicin bolus and 0 of 18 patients given daunorubicin infusion who were monitored with serial echocardiograms had significant decrease in cardiac function (P = 0.10). The major toxicity of the therapy was infections, with 35% of patients developing serious infections during induction and consolidation. Half the patients had an episode of bacteremia from the venous catheter during the 2 years of maintenance.

CONCLUSIONS

Close monitoring of kinetics of cytoreduction can rapidly distinguish between similar therapies, and the surrogate end-point may reduce the need for the long follow-up periods that may still be required to demonstrate differences in EFS. Continuous infusion of daunorubicin had less cardiotoxicity with faster antileukemic activity than bolus infusion. The MSK-NY-II protocol with a 86% 4-year EFS rate and a 95% DFS rate was a promising new regimen for the treatment of average-risk and high-risk ALL.

Inhibitory effects of 2-hydroxy chalcone and other flavonoids on human cancer cell-proliferation

The effect of thirty-one flavonoids on monolayer HeLa cell proliferation was studied and their structure activity relationship was rationalised. The flavones, flavonols and chalcones possessing the C2,3-double bond were the most potent cytotoxic groups of compounds. The IC50 values for 2-hydroxy chalcone (the most potent flavonoid) and the cytotoxic drug colchicine, were 8 muM and < 0.1 muM, respectively. Whilst colchicine was able to inhibit the incorporation of [C-14] thymidine, uridine and leucine into HeLa cells, 2-hydroxy chalcone inhibited the incorporation of the two nucleotides, but not the amino acid. This indicates that the mode of action of 2-hydroxy chalcone and colchicine are different.

Decreased polyglutamylation of methotrexate in acute lymphoblastic leukemia blasts in adults compared to children with this disease

We compared blast cells from adult and pediatric patients with untreated acute lymphoblastic leukemia (ALL) (as separated groups of T-lineage cell and B-lineage cell ALL) to determine if methotrexate (MTX) polyglutamate formation in adult patients might be a contributing cause to the known difference in clinical outcome, since MTX is a key drug in chemotherapy regimens. Adult B-lineage cell ALL blasts and blasts from the patients with T-lineage cell ALL accumulated lower amounts of total MTX and polyglutamates, especially long-chain MTX polyglutamates (glu3-6) than pediatric B-lineage cell ALL blasts. In view of the importance of polyglutamylation of MTX as a determinant of cytotoxicity of this drug, decreased formation of MTX polyglutamates is likely a contributing cause to the lower cure rate in adult ALL and T-lineage cell ALL as compared to childhood B-lineage cell ALL.

Proteinuria and enzymuria in non-insulin-dependent diabetics

Urine albumin, alpha 1- and beta 2-microglobulins, retinol-binding protein (RBP) and N-acetyl-beta-D-glucosaminidase (NAG) were measured in early morning urine samples from 99 non-insulin-dependent diabetic (NIDDM) patients receiving ambulatory care at a primary health care polyclinic. Elevated NAG levels were found in 90% of diabetics regardless of the duration of their disease. Almost half (43.4%) of the subjects had microalbuminuria. Over a third of the subjects without albuminuria had elevated alpha 1-microglobulin levels in their urine. The proportion of subjects with elevated alpha 1 levels increased significantly with the presence of albumin, poor glycaemic control and increased duration of disease. These findings suggest that proximal tubular as well glomerular dysfunction coexist in the NIDDM patients studied.

Defective transport as a mechanism of acquired resistance to methotrexate in patients with acute lymphocytic leukemia

Although the mechanisms of resistance to methotrexate (MTX) are known in experimental tumors made resistant to this drug, little information is available regarding acquired resistance to MTX in patients. A competitive displacement assay using the fluorescent lysine analogue of MTX, N-(4-amino-4-deoxy-N10-methylpteroyl)-N epsilon-(4'-fluorescein-thiocarbamyl)-L-lysine (PT430), was developed as a sensitive method of detection of transport resistance to MTX in cell lines, as well as in blast cells from patients with leukemia. Rapid uptake of PT430 at high concentrations (20 mumol/L) in leukemic blasts resulted in achievement of steady-state levels within 2 hours. Subsequent incubation with the folate antagonists, MTX and trimetrexate (TMTX), which differ in the mode of carrier transport, produced characteristic patterns of PT430 displacement. Flow cytometric analysis of the mean fluorescence intensity in the human CCRF-CEM T-cell lymphoblastic leukemia cell line and its MTX-resistant subline clearly identified the presence of transport deficiency in the resistant subline. Analysis of blasts from 17 patients with leukemia, nine with no prior chemotherapy and eight previously treated with chemotherapy, found evidence of MTX transport resistance in two of the four patients who were treated with MTX and considered to be clinically resistant to the drug. The finding that blast cells of some patients with leukemia considered clinically resistant to MTX is due to decreased MTX transport has important implications for clinical use of this drug and for new drug development.

Coronary artery bypass grafting in patients with left main coronary artery stenosis. Improved survival in a predominantly Oriental population

Over the last 10 years, there has been a reduction of surgical mortality in coronary bypass grafting for left main coronary artery disease. Most of the available literature reports are of Caucasian populations. We report our experience of the surgical treatment of this disease in a predominantly Oriental population. From 1 January 1987 to 30 June 1991, 86 consecutive patients had coronary artery bypass surgery for left main stenosis. There were 65 men and 21 women with an age range of 34 to 80 years (mean age: 58 years SD +/- 8.63). There were no operative deaths and 1 hospital death (1.2%) from a non-cardiac cause. The perioperative myocardial infarction rate was 3.5% (3/86). These results are better than some earlier series in which hospital mortality was reported as high as 12.6% and the preoperative myocardial infarction rate 11.8%. In this series where the patients are predominantly Oriental, the results are comparable if not better than in series reported in centres where the population is predominantly Caucasian.

A prospective randomized trial of adjuvant chemotherapy with bolus versus continuous infusion of doxorubicin in patients with high-grade extremity soft tissue sarcoma and an analysis of prognostic factors

A prospective randomized trial was conducted to compare the cardiotoxic and therapeutic effects of doxorubicin (60 mg/m2 every 3 to 4 weeks) administered by bolus or 72-hour continuous infusion as adjuvant chemotherapy in 82 eligible patients after resection of high-grade soft tissue sarcoma of the extremity or superficial trunk. Cardiac toxicity, defined as a 10% or greater decrease in left ventricular ejection fraction as assessed by radionuclide cineangiography, was evaluated in 69 patients. Cardiotoxicity was seen in 61% of patients in the bolus treatment arm with the median doxorubicin dose of 420 mg/m2. Among patients who received continuous infusion, 42% had cardiotoxicity with a median dose of 540 mg/m2. The rate of cardiotoxicity as a function of the cumulative dose of doxorubicin was significantly higher in the bolus treatment arm (P = 0.0017). Two patients in each group had clinical congestive heart failure, with one cardiac death occurring in each. There was a trend toward a lower rate of metastasis (P = 0.19) and a significantly lower rate of death of disease (P = 0.036) for patients treated with the bolus dose. Cox model analysis identified three unfavorable characteristics for the rate of developing a distant metastasis: blood transfusion within 24 hours of operation (P less than 0.00001), tumor deep to the fascia and 5 cm or more in size (P = 0.0043), and a histologic subtype other than liposarcoma (P = 0.0002). The unfavorable effect of continuous infusion was not selected in the model (P = 0.16). Adjuvant chemotherapy for patients with soft tissue sarcoma is investigational. Furthermore, the impact of perioperative blood transfusion merits further study.

Correction of constriction rings

A refinement in the correction of deep and shallow constriction rings, in which subcutaneous fat and fascial flaps are advanced into the defect to prevent recurrent contour deformities, is presented. A straight-line dorsal closure is preferred, with Z-plasties placed along the side of the digits, forearm, or arm. Long-term follow-up is presented in 58 patients with 116 constriction rings corrected by either traditional serial Z-plasties of skin (n = 61 rings) or this new method of contour correction (n = 55 rings). Specific correction of soft tissue is recommended when tissue is available.

Alterations in self-perceptions among adolescent cancer survivors

Psychosocial adjustment in adolescent cancer survivors has been documented to be quite variable. Factors mediating adjustment need to be identified. The current study is an exploration of the impact that cancer diagnosis and treatment has on adolescent's self-perceptions and the role this has in mediating adjustment in this group. Fifty-eight adolescent survivors of hematologic malignancies were interviewed about alterations in self-perceptions related to their cancer experience and completed a cancer-specific social problem-solving task. Initial findings suggest that cancer universally alters the way adolescent survivors view themselves, but that the alteration can be both positive or negative depending on the meaning ascribed to it.

Basis for natural resistance to methotrexate in human acute non-lymphocytic leukemia

The basis of intrinsic resistance of blasts from patients with acute non-lymphocytic leukemia (ANLL) to methotrexate was studied. MTX polyglutamate formation was measured in blast cells from 19 patients with ANLL and in 7 pediatric patients with acute lymphocytic leukemia (ALL), after in vitro incubation for 24 h with 3H-methotrexate. There was no significant differences seen in the total amount of MTX plus polyglutamates measured between ANLL and ALL blasts, indicating that transport defects do not account for intrinsic MTX resistance in ANLL. However, there were significant differences between the amounts of long chain MTX polyglutamates found in ANLL cells as compared to ALL cells. Most, but not all, ANLL blasts were unable to form long chain polyglutamates. In as much as the level of MTX polyglutamates found in blast cells after MTX administration allows for retention of this drug, this property may explain, at least in part, the refractoriness of most patients with ANLL to methotrexate.

Serum tumor marker half-life during chemotherapy allows early prediction of complete response and survival in nonseminomatous germ cell tumors

The prognostic value and therapeutic utility of monitoring the decay of alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) after chemotherapy for nonseminomatous germ cell tumors was assessed. Patients treated on successive front line chemotherapy protocols at Memorial Hospital between 1979 and 1988 were studied. Marker values taken within the first 90 days of treatment were reviewed for the 198 patients who had initially abnormal values and serial measurements at Memorial Hospital. Since markers frequently increased in an unpredictable fashion in the first week after chemotherapy, prechemotherapy values would be inaccurate for assessment of subsequent half-life. Therefore, the first two values measured greater than 7 days after the start of treatment were used for all calculations of half-life. Among 38 patients who had the two successive AFP measurements elevated, those who later achieved a complete response (CR) had a median AFP half-life of 6.1 days (n = 20), whereas those not achieving CR had a median AFP half-life of 13.3 days (P = 0.02). Among 37 patients with the two successive HCG values elevated, those who later achieved CR had a median HCG half-life of 4.2 days (n = 10), whereas those not achieving CR had a median HCG half-life of 18.4 days (P = 0.04). Forty-two patients who had an AFP half-life greater than 7 days or an HCG half-life greater than 3 days had significantly shorter overall survival (median, 8 months) than the other 156 patients (median not reached) (P less than 0.0001). These 42 patients also achieved CR in lower proportion (29%) than the other 156 patients (89%) (P less than 0.0001). Cox regression identified prolonged marker half-life as the most significant independent predictor of survival. Lack of appropriate decay of serum tumor markers can identify patients unlikely to achieve CR or prolonged survival and thus can be used to select patients during treatment who may benefit from an early change to more aggressive therapy.

Primary colorectal sarcoma. A retrospective review and prognostic factor study of 50 consecutive patients

Fifty patients were admitted to Memorial Hospital, Memorial Sloan-Kettering Cancer Center, New York, NY, with primary colorectal sarcoma between 1948 and 1987. Thirty-one patients (62%) presented with a high-grade tumor, 37 patients (74%) with a tumor larger than 5 cm, and 12 patients (24%) with metastasis. The median survival of the whole group was 33 months, and the median survival of patients who underwent curative operation was 174 months. Nineteen of 32 patients who underwent curative operation were observed to develop distant metastasis after 3 to 209 months. The dominant sites of metastatic disease were the liver and peritoneal cavity. In a multivariable analysis, noncurative treatment and high-grade tumor were the only prognostic factors unfavorably affecting tumor-related mortality. If the type of treatment received was not considered, presentation with metastatic disease and a high-grade tumor were the two unfavorable characteristics that had independent prognostic value. Patients with a tumor that was larger than 5 cm or that was located in the colon had a greater likelihood of having a palliative procedure or high-grade tumor.

Multifactorial analysis of survival in primary extremity liposarcoma

The treatment of extremity soft tissue sarcoma is now directed at limb preservation with the addition of various adjuvant therapies to improve treatment results. To achieve this goal, a knowledge of prognostic factors for extremity soft tissue sarcoma becomes increasingly critical. The object of this study was to analyze prognostic factors for survival in patients with extremity liposarcoma. Eighty-three patients with primary localized extremity liposarcoma, admitted from 1968 to 1978, were retrospectively reviewed. Surgical resection was the primary mode of treatment. Eleven prognostic factors were analyzed. Tumor factors included: histologic subtype, tumor grade, size, depth, invasion of vital structures, and site; operative factors included: type of operation, and surgical margins; and patient factors included: symptoms, age at diagnosis, and sex. Kaplan-Meier survival curves, and univariate and stratified log-rank tests of association were performed. Independent factors for predicting survival were identified using the Cox model stepwise regression technique. In univariate analysis of the entire group of patients, 5 factors were significant for tumor mortality: tumor grade (p = 0.00005), histologic subtype (p = 0.00025), tumor size greater than or equal to 5 cm (p = 0.005), type of surgery/margin (p = 0.0001), and invasion of vital structures (p = 0.008). When associations among all factors were analyzed, it was found that many factors were interdependent. The independent prognosticators were, therefore, determined according to the Cox model technique. For the multivariate analysis, well-differentiated and lipoblastic liposarcomas were excluded because of lack of survival variation within each group. The former group had no tumor-related deaths and the latter group showed 80% tumor mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of protamine dose assay in reversal of heparin following extracorporeal circulation for open heart surgery

The amount of protamine required for the neutralisation of heparin following cardiopulmonary bypass was determined by a Protamine Titration Assay using the principle of the dose--response curve and the patient's estimated blood volume. In 300 open heart surgery patients, infusion of the determined dose of protamine normalised the Activated Clotting Time (ACT) to baseline levels in 97% of these patients and produced adequate hemostasis. Our present study showed that the dose of protamine dropped to 75% of the dose calculated by conventional method of heparin to protamine ratio of 1:1. This had minimised the adverse effects of excessive protamine administration and optimised coagulation control after extracorporeal circulation.

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).

[Investigation into the effect of citric and phosphoric acids on planed root surfaces using S.E.M]

The aim of the present study was to evaluate the effect of citric and phosphoric acid conditioning the diseased root surface on periodontally extracted teeth. Citric acid pH1 and 50 per cent phosphoric acid were topically applied to thoroughly scaled and planed root surfaces for one to three minutes. The specimens were then processed for scanning electron microscopy (S.E.M.) Root surfaces that had received acid treatment after root planing exhibited no smear layer and the overall surface appeared to have an undulating morphology. Whereas, examination of nonacid-treated specimens showed the presence of a smear layer. Furthermore, phosphoric acid treated surfaces demonstrated more irregularity with increasing application time.

Reinduction therapy for advanced or refractory acute lymphoblastic leukemia of childhood

Thirty-four children after multiple relapse or with refractory acute lymphoblastic leukemia were treated with two novel combinations of high-dose cytosine arabinoside, methotrexate, asparaginase, vincristine, and prednisone. The first combination was given to 19 patients. Oncolytic response and marrow hypoplasia was achieved in all. There were four early infectious deaths. Thirteen of the remaining 15 (87%) in whom the response to therapy could be evaluated achieved complete remission. Two achieved good partial remissions. The median duration of complete remission and survival on study was 8 and 10 months, respectively. The four proven and three suspected fungal infections seen in the initial 19 patients was the major toxicity observed. The therapy was modified in the last 15 patients to retain efficacy while reducing the period of neutropenia from a median of 28 to 22 days. No deep-seated fungal infections were seen in these patients. Twelve (80%) achieved a complete remission. Three had an oncolytic response without achieving remission. Eighty-three percent of the 30 evaluable patients, or 74% of all patients entered on study, achieved remission. It is anticipated that the therapy described here will not only achieve another remission in the majority of patients with advanced ALL but that the patients will be able to proceed to alternate therapies with potentially more durable benefit.

Primary cutaneous aspergillosis associated with Hickman intravenous catheters

We describe nine patients with underlying hematologic cancer in whom primary cutaneous aspergillosis developed at the sites of Hickman intravenous catheters. Our patients, 17 to 74 years of age, were all immunocompromised either from their primary disease or from chemotherapy, and the Hickman catheters had been placed to provide venous access for chemotherapy or hyperalimentation or both. Clinical signs of infection included erythema, induration, and cutaneous or subcutaneous necrosis at the point of entry into the subclavian vein, in the subcutaneous tunnel, or at the exit site from the skin. Diagnosis was confirmed by positive wound culture for Aspergillus flavus in all but one patient. Treatment consisted of intravenous amphotericin B, oral flucytosine, and local wound care. Three patients recovered completely without operative débridement; three others recovered after operative débridement and delayed grafting. Two patients died of disseminated aspergillosis, and one died of unrelated causes while recovering from primary cutaneous aspergillosis. Successful treatment required resolution of aplasia or leukopenia, catheter removal, systemic treatment with amphotericin B, and local wound care. We conclude that primary cutaneous aspergillosis, a rare infection, may occur at the sites of Hickman catheters in immunocompromised patients, and that it is a serious complication requiring prompt diagnosis and treatment.

PCNU and recurrent childhood brain tumors

PCNU, the latest nitrosourea analogue to be subjected to clinical trials, held promise as a superior chemotherapy agent for brain tumors because of more favorable biochemical and cytotoxic characteristics in laboratory studies. Thirty-nine children with a variety of recurrent primary CNS tumors, all of whom had evaluable disease, participated in a phase II PCNU trial. Their mean age was 9.7 (3-20) years. PCNU was administered as a 2 hour intravenous infusion in one of 2 dose schedules at 6-7 week intervals; 100-125 mg/m2 for minimally treated patients and 70-90 mg/m2 for heavily treated patients. Response was assessed after 2 courses of chemotherapy after attempting to taper the steroid dose. The overall objective response rate was 18% (7/39) for a mean of 5.9 months (2+ -12). Only partial responses were observed. Disease-specific responses rates were: brainstem glioma--18% (3/17); cerebral glioma--27% (3/12); ependymoma--1/1; and primitive neuroectodermal tumors--(0/9) including 5 medulloblastomas, 2 pineoblastomas and 3 cerebral primitive neuroectodermal tumors. Toxicity was primarily hematologic and clinically significant thrombocytopenia (less than 50,000 mm3) was encountered in 30/38 (79%) patient trials. Modest activity of PCNU in recurrent childhood gliomas is confirmed. Our response rates, using objective CT criteria, are somewhat lower than those reported for BCNU and CCNU. Because of comparable hematologic toxicity and efficacy, intravenous PCNU does not appear to offer a clinical advantage to existing nitrosoureas for children with recurrent brain tumors using a 2 hour intravenous infusion schedule.

Pediatric phase I trial and pharmacokinetic study of trimetrexate

Trimetrexate, a new nonclassical antifolate, was evaluated in a phase I trial in children with refractory cancer including nine with acute leukemia and 21 with solid tumors. The drug was administered as an i.v. bolus injection weekly for three doses, and courses were repeated every 28 days. The dose ranged from 35 to 145 mg/m2. Thirty patients who received a total of 33 courses were evaluable for toxicity, including 19 who were evaluable for hematological toxicity. The maximally tolerated dose for patients with a solid tumor and leukemia was 110 mg/m2. The dose-limiting toxicities were myelosuppression, mucositis and a pruritic, diffuse maculopapular rash. Other side effects observed included transient, mild elevations of serum transaminases, mild nausea and vomiting, and a local phlebitis at the site of injection at higher dose levels. A single patient with delayed drug clearance had evidence of renal toxicity with a transient increase in serum creatinine. The pharmacokinetics of trimetrexate were studied in 25 patients over the entire dose range. There was considerable interpatient variability in total drug clearance (range 9.2 to 215 ml/min/m2) and half-life (2.1 to 20 h). There was a suggestion of a correlation between plasma concentration at 24 h and the development of hematological toxicity at the highest dose level. Trimetrexate was cleared primarily by biotransformation with renal clearance accounting for only 10% of total clearance. Two metabolites of trimetrexate which inhibit the enzyme dihydrofolate reductase were identified in the urine. One of these appears to be a glucuronide conjugate.

Mycotic aneurysm of the pulmonary artery. Direct surgical approach with preservation of lung tissue

A solitary mycotic aneurysm of the right apical lower segmental pulmonary artery developed in an 8 year old child with infective endocarditis, ventricular septal defect and pulmonary hypertension. Surgical treatment was undertaken to prevent rupture and achieved by direct ligation of the feeding vessel and endoaneurysmorrhaphy with preservation of all lung tissue. Successful surgical treatment has been described in eight previous cases of mycotic pulmonary artery aneurysm though in only one adult patient has lung resection been avoided.

Carboplatin and recurrent childhood brain tumors

Carboplatin, a cisplatin analogue, was administered as an intravenous (IV) one-hour infusion in a 4-consecutive weekly dose schedule to 44 patients with recurrent childhood brain tumors. Twenty-four patients were registered on our phase I, and 20 on our phase II studies. The maximum tolerable dose derived from our phase I study was 210 mg/m2/wk in patients with solid tumors, and the recommended dose for subsequent pediatric phase II studies was 175 mg/m2/wk. This dose was administered to 14 patients in the phase I and all 20 patients in the phase II study. Nine of 36 (25%) evaluable patients in the combined studies experienced objective responses for a median duration of 10+ months. Seven of nine responders had received prior cisplatin. Disease-specific response rates were as follows: medulloblastoma, six of 14 (43%) with three complete (CR) and three partial responses (PR); pineoblastoma, one of one (PR); germinoma, one of two (CR); and brainstem glioma, one of eight (13%) (PR). Carboplatin had mild emetic effects but no significant auditory or renal toxicity. Thrombocytopenia (less than 49,000) was encountered in nine of 28 (32%) evaluable trials at a dose of 175 mg/m2/wk. Because of its low potential for auditory, renal, and emetic toxicity, ease of administration, and high disease-specific activity, carboplatin deserves further study in multiagent phase II and III trials, especially in chemotherapy-sensitive diseases such as medulloblastoma.